O. . . I) I) It): II ?Hutu. I I'll! T: II 'I.ll. .H. ?hit. a I 6. ?nu?Fix .. git . . ?atoelectranic oompoa'b'an by caumm cm or mm: mm . 1-75 2.500 California state Water Project Volume in Storage Facilities Number 200 November 1974 Bulletin state of CalHomia The Resources Agency Department of Water Resources STATE OF CALIFORNIA The Resources Agency Department of Wa ter Resources BULLETIN No. 200 CALIFORNIA STATE WATER PROJECT Volume ill Storage Facilities NOVEMBER 1974 NORMAN I B. LIVERMORE, JR. RONALD REAGAN JOHN R. TEERINK Secretary for Resources Governor Director The Resources Agency State of California Department of Water Resources Copies of this bulletin at $5.00 each may be ordered State of California DEPARTMENT OF WATER RESOURCES P.O. Box 388 Sacromento, California 95802 Moke checks payable to STATE California residents add OF CALIFORNIA sates tax. from: FOREWORD This is the third of six volumes which record aspects of the planning, financing, design, construction, and operation of the California State Water Project. The subjects of the other volumes are: \'olume I, History, Planning, and Early Progress; \'olume II, Conveyance Facilities; \'olume I\', Power and Pumping Facilities; \'olume \\ Control Facilities; and \'olume \'I, Project Supplements. The State Water Project conserves and distributes water irrigated agriculture. control, new It recreational to much of California's population and flood control, water quality power generation, opportunities, and enhancement of sports also provides electric fisheries and wildlife habitat. Construction of the first phase of the State Water Project was completed in 1973. The $2.3 reimbursable cost is being repaid by the water users and other beneficiaries. It is expected that another $0.7 billion will be spent during the next decade to construct authorized facilities billion for full operation. This volume discusses storage facilities of the State Water Project and how the various dams and reservoirs function in the Project as a whole. The individual dams and reservoirs are described in detail, the extent of coverage varying with the size, importance, and uniqueness of the individual facility. Geologic conditions at each site are discussed and construction highlights are presented. y John R. Teerink, Director Department of Water Resources The Resources Agency State of California TABLE OF CONTENTS Page FOREWORD iii ORGANIZATION AND POSITIONS OF RESPONSIBILITY ABSTRACT CHAPTER GENERAL xxxvi xli I. Overview 1 Upper Feather River Division 2 Oroville Division 3 North San Joaquin Division and South Bay Aqueduct San Luis Division South San Joaquin and Tehachapi Divisions Mojave Division 4 Santa Ana Division West Branch Division Design 7 7 8 8 Construction CHAPTER 6 6 8 II. FRENCHMAN DAM AND LAKE General Description and Location Purpose Chronology Regional Geology and Seismicity Design Dam 13 13 14 14 14 14 14 Description 14 Stability Analysis 14 Settlement 14 Construction Materials IS Foundation 15 Instrumentation 18 Outlet Works 18 Description 18 Structural Design 18 Mechanical and Electrical Installations Spillway 18 18 Description 18 Hydraulics 18 Structural Design Construction 18 24 Contract Administration 24 Diversion and Care of Stream 24 Foundation 24 Dewatering 24 Excavation 24 Grouting Handling of Borrow Materials 24 24 Impervious 24 Drain 24 TABLE OF CONTENTS— Continued Page Slope Protection Embankment Construction 24 24 Impervious 24 Drain 26 Slope Protection 26 Outlet Works 26 Spillway 26 Excavation 26 Anchorage Concrete Placement Concrete Curing 27 Backfill 28 27 27 Concrete Production 28 Reservoir Clearing 28 Closure 28 29 Bibliography CHAPTER III. ANTELOPE DAM AND LAKE General 31 Description and Location 31 Purpose 32 Chronology Regional Geology and Seismicity Design Dam 32 32 32 32 Description 32 Stability Analysis 33 Settlement 33 Construction Materials 33 Foundation 33 Outlet Works 36 Description 36 Structural Design 36 Mechanical Installation 36 Spillway 36 Description 36 Hydraulics 36 Structural Design Construction 36 40 Contract Administration 40 Foundation 40 Dewatering 40 Excavation 40 Grouting Handling of Borrow Materials Impervious 40 40 40 Pervious 40 Slope Protection 42 Embankment Construction 42 TABLE OF CONTENTS— Continued Page Impervious 42 Pervious 42 Slope Protection 42 42 Outlet Works Excavation 42 Concrete 42 42 Spillway 42 Excavation Concrete Concrete Production 42 Reservoir Clearing 42 Closure 43 Instrumentation 43 42 45 Bibliography CHAPTER I\'. GRIZZLY VALLEY DAM AND LAKE DAVIS 47 General Description and Location 47 Purpose 48 Chronology Regional Geology and Seismicity Design Dam 48 48 48 48 Description 48 Stability Analysis 49 Settlement 49 Construction Materials 49 Foundation 49 Instrumentation 51 Outlet Works 51 Description 51 Hydraulics 51 Structural Design 51 Mechanical Installation 51 51 Spillway Description 51 Hydraulics 51 Structural Design 51 Grizzly \'alley Pipeline 51 56 Construction Contract Administration 56 Diversion and Care of Stream 56 Excavation for Dam and Dewatering Foundation 56 Handling of Borrow Materials 56 Embankment 56 Outlet Works 56 Excavation 56 Concrete 58 TABLE OF CONTENTS—Continued Page Mechanical Installation 59 Spillway Excavation 59 59 59 Concrete Concrete Production 60 Reservoir and Other Clearing 60 Reservoir Filling 60 Initial 61 Bibliography CHAPTER V. OROVILLE DAM AND LAKE OROVILLE 63 General Description and Location 63 65 Purpose Chronology and Alternative Dam 65 Studies Construction Schedule 67 Regional Geology and Seismicity 67 Design 68 Dam 68 Description 68 Configuration and Height 68 Construction Materials 71 Laboratory Testing 73 Test 74 Fills 74 Stability Analyses Other Earthquake Considerations Settlement, Pore-Pressure, and Crest-Camber Studies Foundation Site Geology ^ 77 77 77 77 Exploration 78 Excavation Criteria 78 Grouting Core Block Grout Gallery Tunnel Systems 78 78 81 81 Diversion-Tailrace Tunnels 82 River Outlet 83 Diversion Tunnel Intake Portal Structures 83 Diversion-Tailrace Tunnel Outlet Portal Structures 88 River Outlet Access Tunnel 88 Powerhouse Emergency Exit Tunnel Core Block Access Tunnel Palermo Outlet Tunnel 88 Spillway Headworks Chute Emergency Spillway Saddle Dams Location 88 88 92 93 100 100 100 100 1 TABLE OF CONTENTS— Continued Page 100 Description Site Geology 105 Embankment Design 105 Foundation Grouting 105 Construction Materials 105 Stability Analysis 105 Instrumentation 107 Dam 107 107 Spillway Saddle Dams 107 107 Relocations Western Pacific Railroad Tunnels 107 107 109 Bridges Feather River Bridge 109 West Branch Bridge North Fork Bridge 109 110 Feather River Railway 110 Oroville-Quincy Road 1 Forbestown Road to Bidwell Bar Bridge Bidwell Bar Bridge to Original County Road Bidwell Bar Bridge Canyon Creek Bridge Oroville-Feather Falls Road B. U.S. 10 110 Ill 1 1 112 113 Abbott Goldberg Bridge 113 Highway 40A 114 Nelson Bar County Road 114 Bennum Road 114 Lunt Road 114 U.S. Forest Service Roads 114 114 Construction..... Contract Administration 1 14 Early Contracts 1 16 116 Relocations Diversion Tunnel No. 1 Palermo Outlet Works Initial Dam Construction Activities Diversion of River and Dewatering of Foundation Foundation Preparation 116 1 17 118 118 119 Stripping 119 Core Trench Excavation Grout Gallery Excavation Core Block Excavation 1 19 1 19 Factors Affecting Contractor's Progress 120 Core Block Grout Gallery Core Block Access Tunnel 119 120 121 122 TABLE OF CONTENTS—Continued Page Production of Embankment Materials 122 Pervious 122 Impervious 123 Training Dikes 125 Materials Hauling Facilities 125 Dam Embankment 125 Chronology 125 Construction Equipment 126 Construction Operations 126 128 Electrical Installation Grounding Grids Lighting and Power Systems 128 128 Structural Grouting of the Core Block 128 Diversion Tunnel No. 130 2 Equalizing Tunnel 13 Valve Air-Supply Tunnel 13 River Outlet Works 13 River Outlet Access Tunnel 13 Emergency Exit Tunnel 13 Closure Sequence 13 Spillway 13 Clearing 13 Excavation 13 Drain System 13 Concrete 134 Electrical Installation 134 Gate 134 Installations Grouting Program Grout Curtain Blanket Grouting Envelope Grouting 134 Reservoir Clearing 135 Saddle Dams 135 135 135 136 Foundation 136 Construction Materials 136 Mine Adit Plug 137 Construction of Embankment CHAPTER 137 139 Bibliography VI. THERMALITO DIVERSION DAM General 141 Description and Location 141 Purpose 141 Chronology Regional Geology and Seismicity Design Foundation Site Geology 141 143 143 143 143 TABLE OF CONTENTS—Continued Page Strength 143 Overpour Section 143 Description 143 Hydrology 143 Structural Design 144 Spillway Gates and Hoists 144 Stability 144 Nonoverpour Sections Thermalito Canal Headworks 144 Radial Gates and Hoists 148 Foundation 148 Stability Analysis Embankment Section 144 148 148 Description 148 Construction Materials 148 Stability Analysis Construction 148 148 Contract Administration 148 Diversion and Care of River 150 West Bank Channel 150 Closure 150 East Bank 152 Foundation 150 152 Excavation 152 Preparation 152 Grouting 152 Embankment Construction 152 Description 152 Random Backfill 152 Impervious Core 152 Select Backfill 152 Consolidated Backfill 152 Riprap 152 Concrete Production Construction Phases 153 153 Concrete Mixing and Materials 153 Concrete Placing and Formwork 153 Radial Gates and Hoists 153 Spillway Gates 153 Canal Headworks Gates 153 Hoists for Radial Gates 153 Trunnion Beams and Stressing Operation 155 Slide Gates and Operators 155 Other Installations 155 Reservoir Clearing 155 Instrumentation Bibliography 155 157 TABLE OF CONTENTS—Continued CHAPTER VII. THERMALITO FOREBAY, AFTERBAY, AND POWER CANAL Page 159 General Description and Location 159 Purpose 162 Chronology Regional Geology and Seismicity Design Dams 162 163 163 163 Description 163 Stability Analysis 163 Settlement 163 Construction Materials 169 Foundation 169 Instrumentation 169 Forebay Inlet-Outlet 170 Thermalito Power Canal 170 Canal Section 170 Filter Subliner 170 Lining 170 Drainage Structures 170 Turnouts Tail Channel 172 Afterbay Irrigation Outlets 172 Afterbay River Outlet Flood Routing 173 172 — 172 Thermalito Complex OroviUe-Chico Road Bridge 184 Oroville-Cherokee Road Overhead Crossing 184 Oroville-Cherokee Road Bridge 184 Nelson Avenue Larkin Road 184 Relocations 184 Oroville-Willows County Road State Highway 184 162 Construction 185 185 185 Contract Administration 185 Foundation 185 Stripping 185 — Forebay Excavation — Afterbay Excavation Grouting Embankment 185 185 186 Materials and Construction — Forebay Impervious— Afterbay Pervious— Forebay Pervious — Afterbay Impervious 186 186 187 187 187 Riprap 187 "Top-Out" Operation 187 TABLE OF CONTENTS— Continued Page Thermaljto Power Canal 188 Excavation 188 Horizontal Drains 189 Filter Subliner 189 Concrete 189 Weeps 190 Stone Protection 190 Recreation Area 190 Tail Channel 191 Excavation 191 Placement of Channel Protection 191 Miscellaneous Channel Excavation 191 Irrigation Outlets 193 Western Canal and Richvale Canal 193 PG&E 193 Lateral 194 Sutter-Butte Canal 194 River Outlet Headworks 195 Fish Barrier Weir 195 Concrete Production 196 Reservoir Clearing 196 196 Closure Instrumentation and Toe Drain Observations 196 196 Seepage Forebay 196 Afterbay 196 Tail Channel 197 Bibliography CHAPTER 199 VIII. CLIFTON COURT FOREBAY General 201 Description and Location 201 Purpose 201 Chronology Regional Geology and Seismicity Design Dam 201 201 202 202 Description 202 Foundation 202 Construction Materials 202 Stability Analysis 207 Settlement 207 Control Structure 207 Intake Channel Connection 208 Intake Channel Closure 208 Piping and Drainage Systems 208 Construction Contract Administration 208 208 TABLE OF CONTENTS— Continued Page Dewatering and Drainage 208 Reservoir Clearing 211 Excavation 211 211 Forebay Borrow Area A 211 Structural 211 Ditch and Channel 211 Handling of Borrow Materials 211 Embankment Construction 212 Compacted Material Uncompacted Material 212 Slope Protection 212 Closure Embankment Breaching Levees Control Structure 212 212 213 213 Concrete 213 Mechanical Installation 213 Concrete Production 213 Electrical Installation 213 Instrumentation 213 Bibliography CHAPTER 217 IX. BETHANY DAMS AND RESERVOIR 219 General Description and Location 219 Purpose 219 Chronology Regional Geology and Seismicity Design Dams 220 220 221 221 Description 221 Stability Analysis 221 Settlement 221 Construction Materials 221 Foundation 228 Instrumentation 228 Outlet Works Forebay Dam 228 228 Outlet to South Bay Aqueduct 228 Outlet to California Aqueduct 228 Spillway 228 Construction 235 Contract Administration 235 Diversion and Care of Stream 235 Foundation 235 Grouting Handling of Borrow Materials 235 Embankment Construction 237 237 TABLE OF CONTENTS— Continued Page Spillway 238 Outlet Works 238 Concrete Production 238 Mechanical and Electrical Installations 238 Reservoir Clearing 238 Placing Topsoil and Seeding 238 Embankment Test 238 Installation 239 Bibliography CHAPTER X. DEL VALLE DAM AND LAKE DEL VALLE General 241 Description and Location 241 Purpose 242 Chronology Regional Geology and Seismicity Design Dam 242 242 243 243 Description 243 Stability Analysis 243 Settlement 243 Foundation 243 Construction Materials 246 Instrumentation 246 Conservation Outlet Works 246 Flood Control Outlet Works 251 Spillway 251 Description 251 Hydraulics 253 Structural Design 253 Mechanical and Electrical Installations 253 Flood Control Outlet Works 253 Conservation Outlet Works 257 Construction 257 Contract Administration 257 Diversion and Care of Stream 257 First Construction Season 257 Second Construction Season Third Construction Season Foundation Dewatering 257 257 257 257 Excavation 257 Flood Cleanup 258 Dam Foundation Grouting 258 Blanket Grouting 258 Curtain Grouting 258 Embankment Materials 258 Impervious 258 Transition 259 TABLE OF CONTENTS—Continued Page Filter 259 Drain 259 Outer Shell 259 Random 259 Slope Protection 259 Embankment Construction Impervious and Transition Filter and Drain 261 261 261 Outer Shell 261 Random 262 Slope Protection 262 Instrumentation Conservation Outlet Works 262 262 Outlet Portal 262 Inlet Portal 262 Tunnel 262 Concrete 262 Grouting 263 Installation of 60-Inch Steel Pipe 263 Intake Structure 263 Hydraulic Testing 264 Testing Butterfly Valves 264 Inlet Control Building 264 Flood Control Outlet Works and Spillway Tunnel 264 Description 264 Inlet 264 Pressure Tunnel 265 Trashrack 265 Spillway Crest, Shaft, and Gate Chamber 265 Downstream Portal Spillway Tunnel 266 Gates 267 Gate Chamber Access 267 Stilling Basin 267 Return Channel 268 Concrete Production 268 Reservoir Clearing 268 Closure 268 269 Bibliography CHAPTER 266 XI. SAN LUIS JOINT-USE STORAGE FACILITIES General 271 Description and Location 271 Purpose 273 Chronology 276 Operation Design Dams San Luis 276 279 279 279 TABLE OF CONTENTS—Continued Page O'Neill Forebay 280 Los Banos Detention Little Panoche Detention 280 Inlets, Outlets, and Spillways 280 280 San Luis Reservoir 280 O'Neill Forebay 280 Los Banos Reservoir 284 Little Panoche Reservoir 284 Instrumentation 289 Recreation 289 Bibliography CHAPTER 291 XII. CEDAR SPRINGS DAM AND SILVERWOOD LAKE General 293 Description and Location 293 Purpose Chronology Regional Geology 294 Seismicity 297 Major Faults Design Criteria for Maximum Credible Accident Design Criteria for Embankment Design Criteria for Structures Design Dam 295 297 297 297 298 298 298 298 Description 298 Foundation 298 Embankment Layout 302 Grouting 302 Construction Materials 302 Stability Analysis 302 Seismic Considerations 302 Settlement 303 Instrumentation 303 Debris Barriers 303 Description 303 Canyon Cleghorn Canyon San Bernardino Tunnel Approach Channel Drainage Gallery and Access Tunnel Miller 306 306 306 306 Exploration Adit 306 Drainage Gallery 306 Access Tunnel 306 Spillway Description 3 3 Excavation 3 Backfill 3 Drainage 3 TABLE OF CONTENTS— Continued Page Hydraulics 313 Structural Design 3 315 Description 315 Hydraulics 315 Structural Design Mojave Siphon Inlet 315 Works 319 Description 319 Hydraulics 319 Structural Design 3 Las Floras Pipeline Hydraulics 320 Valve Vaults 320 Blowoff Structures 320 Energy Dissipator Structure 320 320 Outlet Works 320 Slide Gates 320 Fixed-Cone Dispersion Valve 322 Lubrication System 323 Service Facilities 323 Heating and Air-Conditioning System \'entilation System Las Floras Pipeline 323 323 Shutoff Valve 323 Flow Metering 323 Control Valves 323 Air- Vacuum Valve 324 324 Electrical Installation Operating Equipment ' 323 323 Domestic (Potable) Water Supply System ' 19 320 Mechanical Installation ' 14 Outlet Works Emergency Engine-Generator Equipment Construction Contract Administration 324 Set 324 324 326 326 Exploration Adit 326 Diversion and Care of River 326 Dam 327 Foundation Dewatering 327 Excavation 327 Cleanup and Preparation Handling of Borrow Materials 327 327 Description 327 Impervious 327 Pervious and Slope Protection 328 Waste Areas Embankment Construction Impervious 328 328 328 TABLE OF CONTENTS—Continued Page Pervious 329 Slope Protection 329 Riprap 330 Spillway 330 Open-Cut Excavation 330 Structural Excavation 330 Concrete Placement 330 Mojave Siphon Inlet Works 330 Excavation 330 Concrete Placement 331 Concrete Piles 331 Mojave Siphon Extension 331 Pipe Installation 331 Debris Barriers 331 Drainage Gallery 331 Concrete Placement 331 Drainage Gallery Extension 332 Access Tunnel 332 Completion Concrete Placement 332 Outlet Works Tunnel 332 332 Excavation 332 Concrete Placement 333 Air Shaft Tunnel 334 Excavation 334 Concrete Placement 334 Concrete Production 334 Grouting Dam Foundation 33 33 Spillway 33 Tunnel Gate Chamber 33 Air Shaft 33 33 Reservoir Clearing 33 Bibliography CHAPTER 33 XIII. PERRIS DAM AND LAKE General PERRIS 339 Description and Location 339 Purpose 340 Chronology Regional Geology and Seismicity Design Dam Description 340 340 341 341 341 Stability Analysis 344 Settlement 344 Construction Materials 344 Foundation 345 Instrumentation 345 TABLE OF CONTENTS—Continued Page Inlet Works 345 Description 345 Hydraulics 345 Pipe Structural Design 348 Outlet Works 348 Description 348 Intake Channel 348 Tower Works Tower Mechanical Outlet Works Outlet 348 Installation 348 Outlet Works Tunnel 349 Outlet Works Delivery Facility 349 Delivery Facility Mechanical Installation 353 Spillway 355 Description 355 Hydraulics 355 Construction 356 Contract Administration 356 Dam 356 Foundation Excavation 356 Grouting Handling of Borrow Materials Clay Borrow Area Lake Borrow Area 356 Embankment Construction 359 Mandatory Waste Area No. Works Outlet Works Outlet Works Delivery 2 358 358 361 361 Inlet 361 Facility Spillway 362 362 Clearing and Grubbing CHAPTER 358 XIV. 362 PYRAMID DAM AND LAKE General 365 Description and Location 365 Purpose 367 Chronology and Alternative Dam Considerations Regional Geology and Seismicity Design Dam 367 368 369 369 Description 369 Foundation 369 Construction Materials 369 Stability Analysis 374 Settlement 375 Instrumentation 375 Drainage Adits 375 Diversion Tunnel 375 Intake Tower Stream Release Facility Fixed-Cone Dispersion Valves 375 378 382 TABLE OF CONTENTS—Continued Page Shutoff Valves 383 Spillway 384 Grouting Overpour Weir Head works Structure Approach Walls Radial Gate Bulkhead Gate Concrete Chute Earthquake Criteria 384 384 384 384 384 384 384 384 Concrete and Steel Structures 389 Hydrodynamic Pressures 389 Earth Pressures 389 Materials and Design Stresses 389 389 Electrical Installation Interstate 5 Embankments 389 Description 389 Shear Strength Properties 391 Stability Analyses 391 Borrow Areas 391 Culvert Reinforcement 391 391 Culvert Extensions Construction 392 Contract Administration 392 Diversion Tunnel 392 Excavation 392 Concrete 392 Diversion and Care of Stream 393 Foundation Preparation 393 Overburden Shaping Cleanup Grouting Channel Excavation 393 Embankment 394 393 394 394 394 Materials Impervious 394 Rock 394 Shell 395 Transition and Drain Embankment Construction 396 Impervious 396 Shell 397 Transition and Drain 397 397 Spillway Drainage 397 Reinforcing Steel 397 Concrete Production 397 398 Forms Concrete Placement .'. 398 TABLE OF CONTENTS—Continued Page 399 Radial Gate Access and Air-Supply Tunnel 399 Adits 400 Completion of Outlet Works Intake Structure Diversion Tunnel Plug Mechanical and Electrical Installations 400 Instrumentation 402 403 Bibliography CHAPTER 401 401 CASTAIC XV. DAM AND LAKE 405 General Description and Location 405 Purpose 407 Chronology Regional Geology and Seismicity Design of Elderberry Forebay Operation 407 409 409 409 Embankment 409 Emergency Spillway Outlet Works 409 Design of Castaic Dam Diversion Tunnel Hydraulics 409 409 409 409 Structural Design 412 Grouting 415 Embankment 415 Description 415 Stability Analysis 415 Construction Materials 415 Test 418 Fill Settlement 418 Seepage Analysis 418 Transition and Drain 418 Upstream Slope Protection Dam Axis Alignment Changes 418 Foundation Site Geology Excavation Spillway 418 419 419 419 419 Flood Routing 419 Approach Channel Weir 419 Transition 421 419 Chute 421 Stilling Basin 421 Return Channel Retaining Wall Design 421 Floor Design 422 Open-Cut Excavation 422 421 TABLE OF CONTENTS—Continued Page Drainage 422 Foundation 422 Outlet Works 422 Hydraulics 432 Structural Design of High Intake Tower 432 High Intake Tower Access Bridge 433 Instrumentation 433 Castaic Lagoon 433 Mechanical and Electrical Installations High Intake Port Low 437 \'alves 437 Intake Gate System 440 High Intake Auxiliary Equipment Turnout Guard \'alves 440 Stream Release 454 Facilities Stream Release Regulating \'alves Stream Release Guard \'alves 449 454 454 459 Construction Contract Administration 459 Foundation Trench 459 Diversion Tunnel 459 Open-Cut Excavation Underground Excavation 459 Pervious Backfill and Riprap Placement 460 Tunnel Lining Concrete 460 Structural and 459 Diversion and Care of Stream 460 Dam 461 Foundation 461 Excavation Grouting Foundation Preparation Handling of Borrow Materials Impervious Filter 463 464 464 464 464 and Drain Pervious 464 Random 465 Soil-Cement 465 Downstream Cobbles 465 Embankment Construction Filter 465 465 Impervious and Drain 465 Pervious 465 Random 466 Soil-Cement 466 Downstream Cobbles Boat Ramp and Parking Area Outlet Works High Intake Tower High Intake Tower Access Bridge Piers 466 466 466 — Excavation —Concrete Operations 466 467 468 TABLE OF CONTENTS—Continued Page Access Bridge Girders and Deck 468 Low 468 Intake Tower 469 Penstock 469 Spillway Excavation 469 Concrete 470 Flip-Bucket Piles 470 Structural Backfill 470 Lagoon Control Structure Clearing, Grubbing, and Erosion Control Castaic 471 471 Reservoir Clearing 471 Clearing and Grubbing of Other Areas 471 Erosion Control 472 473 Bibliography APPENDIXES Appendix A: CONSULTANTS 475 Appendix ENGLISH TO METRIC CONVERSIONS AND PROJECT STATISTICS 479 B: 1 FIGURES Figure Number 1 Page Location Map —State Water Project Reservoirs xlii 2 Upper Feather River Division 3 Oroville Division 3 4 South Bay Aqueduct and Part of North San Joaquin Division.. 4 2 5 San Luis Division S 6 Mojave Division 6 Ana Division 7 Santa 8 West Branch Division 9 Location of Construction Project Offices 7 9 10 Map— Frenchman Dam and Lake View — Frenchman Dam and Lake 10 Location 12 11 Aerial 13 12 Area-Capacity Curves 13 General Plan and Profile of 14 20 18 Embankment Sections Location of Embankment Instrumentation General Plan and Profile of Outlet Works Outlet Works Rating Curve (24-Inch Hollow-Cone Valve) Outlet Works Rating Curve (8-Inch Globe Valve) 19 General Plan and Profile of Spillway 23 20 Location of Borrow Areas and Frenchman 15 16 17 15 Dam 16 Dam Site 17 19 21 22 25 26 23 Embankment Construction Completed Embankment Outlet Works Concrete Placement 24 Spillway Chute 27 25 Spillway Flip Bucket 26 Location 27 Aerial 28 Area-Capacity Curves 29 General Plan and Profile of 2 22 27 27 Map— Antelope Dam View 26 and Lake — Antelope Dam and Lake 30 31 33 Dam 34 30 Embankment 31 General Plan and Sections of Outlet Works 32 Outlet 33 General Plan and Sections of Spillway 39 34 40 37 Temporary Diversion Pipe and Outlet Works Conduit Drilling Grout Hole Left Abutment Auxiliary Dam Location of Borrow Areas and Antelope Dam Site Outlet Works Control Structure 38 Spillway 43 39 Location of 40 Location 41 Aerial \'iew 42 Area-Capacity Curves 49 43 Dam — Plan, 50 35 36 Sections 35 Works Rating Curves 38 — Embankment Instrumentation Map— Grizzly Profile, Dam and Lake Davis Dam and Lake Davis Valley —Grizzly Valley 37 and Sections 40 41 42 44 46 47 46 Embankment Instrumentation General Plan and Profile of Outlet Works Outlet Works Rating Curve 54 47 General Plan and Profile of Spillway 55 44 45 Location of 52 53 FIGURES—Continued Figure Number < '^'S^ Dam 48 Location of Borrow Areas and Grizzly Valley 49 Completed Embankment 50 Control House at 51 Control House at 52 Outlet Works 53 Spillway Chute 54 Spillway Approach and Log 55 Location 56 Aerial 57 Area-Capacity Curves 58 Model of Multiple-Arch Concrete 59 60 Embankment Plan Embankment Selected 61 1964 Cofferdam 62 Location of Borrow Areas and Oroville 63 Dredge Tailings 64 Stability Analysis 65 Embankment Model on Shaking Table 76 66 78 67 Grouting Core Block 68 Diversion Tunnels Nos. 69 Grout Envelope 84 70 Intake Structures Plan 85 71 Diversion Tunnel No. 1 72 Diversion Tunnel No. 2 57 58 Dam Crest Dam Toe 58 58 —Butterfly Valve in Outlet Structure 59 59 Map— Oroville View Site Boom 60 Facilities 62 —Oroville Dam and Lake Oroville 63 65 Dam 66 69 — Sections and Profile 70 71 Dam 72 Site 73 Summary 75 79 1 and 2 —Draft-Tube Arrangement .... 80 73 — Intake Portal Sections — Intake Portal Sections Diversion Tunnel Outlet Structures — Plan and Sections 89 86 87 74 Miscellaneous Tunnels 90 75 Palermo Outlet Tunnel 91 76 General Plan of Spillway 94 77 Flood Control Outlet 78 Spillway Chute 96 79 — Plan, Profile, and Typical Sections Emergency Spillway — Sections and Details 80 Hydrologic and Hydraulic Data 98 81 Spillway and Flood Control Outlet Rating Curves 82 Flood Control Outlet 83 Bidwell Canyon Saddle 84 Bidwell Canyon Saddle — Plan and Elevation 95 97 99 — Elevations and Sections Dam— Plan 101 and Profile 102 86 Dam — Sections and Details Parish Camp Saddle Dam — Plan, Profile, and Sections Location of Borrow Areas and Parish Camp Saddle Dam 87 Western Pacific Railroad Relocation 88 Feather River Bridge 109 89 109 90 West Branch Bridge North Fork Bridge 91 Bidwell Bar Bridge 112 92 B. 93 Diversion Tunnel No. 94 Stage 85 —Tunnel Locations Diversion 104 Site.. 106 108 110 Abbott Goldberg Bridge 1 103 1 Intake Portal After Backfilling 114 117 118 1 FIGURES— Continued Figure Page Number 95 Stage 2 Diversion Earth Dike 96 Stage 3 Diversion 97 Wood Forms— Core 98 Steel Cantilever Panel 99 25-Ton-Capacity Cableway 120 100 Rail-Mounted Steel Towers 121 101 121 102 Grout Gallery Bucket Wheel Excavator 103 Initial Set-In of 104 Transfer Conveyor and Bucket Wheel Excavator 123 105 Pervious Loading Station 123 106 Impervious Loading Station 123 107 124 109 Haul Route Automatic Car Dumper Conveyor Across Feather River 110 Traveling Stacker 1 1 Reclaim Tunnel 112 Distribution Conveyors on Right 113 115 Truck-Loading Hopper Transfer Conveyor Electrical Grounding Grids 116 Cracking of Core Block 117 Wedge 118 Lowering Stoplogs 119 Location 120 Aerial 121 General Plan and Profile of 122 Spillway Rating Curve 123 Spillway Sections 124 Power Canal Headworks Plan, West Bank Diversion Plan Channel Bypass (Aerial View) 108 1 14 125 126 127 128 129 130 131 132 133 134 135 136 137 138 Seat 1 Forms —Core Block Removal 122 125 126 126 Reclaim Stockpile 126 in Abutment 127 129 130 Diversion Tunnels 131 132 Dam Dam Diversion Dam 140 141 142 145 146 — Profile, and Sections Channel Bypass, Closure, and East Bank Diversion Plan Cofferdam Closure Location of Concrete Mixes Used in Dam Structure Location Map Thermalito Forebay and Afterbay Aerial \'iew Thermalito Forebay Aerial View Thermalito Afterbay Area-Capacity Curves Thermalito Forebay Area-Capacity Curves Thermalito Afterbay General Plan of Forebay Main Dam Forebay Dam Sections and Details Forebay Ruddy Creek and Low Dams Sections Afterbay Dam Sections and Details — — — — — Dam 127 127 —Thermalito Diversion — — — 120 122 Excavation at 19 120 Block Map— Thermalito View 119 147 149 150 151 152 154 158 159 159 161 162 164 165 166 167 168 139 Afterbay 140 Thermalito Power Canal 170 141 Power Canal Sections 171 Details FIGURES—Continued Fjure p Number —Thermalito Power Canal 142 Typical Horizontal Drain 143 Typical Turnout 144 Western Canal and Richvale Canal Outlets 145 146 Western Canal and Richvale Canal Outlets Pacific Gas and Electric Outlet 147 Pacific 148 Sutter-Butte Outlet 149 Sutter-Butte Outlet 150 River Outlet 151 River Outlet Headworks and Fish Barrier Weir 152 153 Grouting Foundation of Forebay Main Dam Hand Placement of Forebay Dam Adjacent to Powerplant Wing- 154 Afterbay 155 Placement of Zone 156 Riprap Placement 188 157 Slide at Left Side of 188 159 Power Canal Placing Type II Drain Pipe Along Toe of Slope and Type B Filter Material on Invert of Power Canal Placement of a Slope Mat 160 Reinforcing Steel Being Placed in Canal Invert 189 161 Slip Form Lining Operation on Thermalito tion Slopes 190 162 Closeup of Slip Form Lining Operation on Thermalito Power Canal Transition Slopes 163 169 Bedding Placement on Tail Channel Location of Miscellaneous Channels Western Canal and Richvale Canal Outlets Upstream View Pacific Gas and Electric Lateral Outlet Conduit Sutter-Butte Canal Outlet Sutter-Butte Canal Outlet Conduits Sutter-Butte Canal Outlet Intake 170 River Outlet 171 River Outlet— Fish Barrier Weir 195 172 Location Map—Clifton 200 173 Aerial Gas and 174 —Thermalito Power Canal Electric Outlet 175 176 — Isometric View .... 178 — Isometric View 179 180 — Isometric View 181 182 — Isometric View wall 158 164 165 166 167 168 Construction 186 187 4A— Afterbay Dam 187 189 189 Power Canal Transi- — 191 191 192 .. 193 193 194 194 195 195 Court Forebay —Clifton Court Forebay View Embankment 175 General Plan of Forebay Sections 201 203 — North General Plan of Forebay — South 178 Gated Control Structure Control Structure and Inlet Channel Connection to West Canal and Old River (in background) 179 Closure 180 Drainage System 181 Test Installations 182 Location 183 Area-Capacity Curves 184 Bethany Forebay 177 183 186 Dam 174 176 177 Embankment 204 205 206 207 209 210 214 Map— Bethany Dams — and Reservoir Bethany Reservoir 218 220 220 FIGURES— Continued Figure Page Number 185 186 Bethany Reservoir Bethany Forebay Dam — Plan, 221 — Plan, Profile, and Sections 222 190 Dam Dam Dam Dam 191 Location of Borrow Areas and Bethany Forebay 192 Foundation Excavation and Drainage 193 Location of Forebay 194 Outlet Works— Plan 195 Outlet Works Rating Curve 196 Connecting Channel 197 Temporary Spillway 198 Bethany Forebay and Excavation for Adjacent 199 Foundation Grouting 200 Location of Borrow Areas and Adjacent 201 Bethany Forebay 202 Location Map) 203 Aerial 204 Area-Capacity Curves 243 205 General Plan of Dam 244 206 207 Embankment Sections and Profile Location of Embankment Instrumentation 208 Conservation Outlet Works 209 Inclined Intake Structure 249 210 Conservation Outlet Works Rating Curve 250 211 General Plan of Flood Control Outlet Works 252 212 Flood Hydrographs 254 213 Spillway Stilling Basin 255 214 Single-Line Electrical Diagram 256 215 Left Abutment Excavation and Curtain Grouting Location of Borrow Areas and Del Valle Dam Site 259 261 218 Embankment Construction Combined Outlet Works 219 Concrete Saddles for 60-Inch Pipe 263 220 Sloping Intake Structure 263 221 Tunnel Supports 264 222 Trashrack 264 223 Spillway Crest 265 224 Spillway Shaft Excavation Support 265 225 Tunnel Crown Placement Forms 266 226 Stilling Basin 267 227 Location 228 Aerial \'iew 229 San Luis Reservoir Recreation Areas President John F. Kennedy and Governor Edmund G. Brown Pushing Plungers to Detonate Explosives for Ground Breaking 187 188 189 216 217 230 No. 1 2— Plan, 3— Plan, 4— Plan, No. No. No. Profile, and Sections 223 Profile, and Sections 224 Profile, and Sections 225 Profile, and Sections 226 Dam Dam Site Details — Dam No. 3 Instrumentation 231 232 — Plan, Profile, and Sections — Bethany 235 Dams 236 Construction Dam Valle and Lake Del Valle — Plan, Profile, and Sections Dam 237 240 241 245 247 248 260 262 Luis Joint-Use Storage Facilities Luis 235 Dam Forebay — —San 233 234 Dams — Del Valle Dam and Lake Del Valle Map— San 229 230 and Profile Dam View— Del 227 and Reservoir 270 271 272 276 FIGURES—Continued Figure P^g^ Number — Los Banos Reservoir 231 Flood Diagram 232 General Plan and Sections of San Luis 278 233 Placing and Compacting 279 234 Wheel Excavator Cutting on 50-Foot-High Face Basalt Hill Rock Separation Plant 235 236 237 238 239 240 277 Dam and O'Neill Forebay Embankment— San Luis Dam Dam — Plan, Profile, and Little Panoche Detention Dam — Plan, Profile, Spillway and Outlet Works — San Luis Dam Los Banos Detention 279 279 Sections 281 and Sections 282 283 — Trashrack Structure and Access Bridge San Luis Dam Spillway— O'Neill Forebay Dam Los Banos Detention Dam Spillway and Outlet Plan and 284 285 246 — way Profile Los Banos Detention Dam — Outlet Profile Little Panoche Detention Dam — Spillway Plan and Sections Location of Instrumentation — San Luis Dam Location Map— Cedar Springs Dam and Silverwood Lake Aerial View — Cedar Springs Dam and Silverwood Lake 247 Area-Capacity Curves 295 248 Dam 296 249 Fault Uncovered 250 252 Embankment Plan Embankment Sections Embankment Sections and Details 253 Determining the Index 254 Location of Instrumentation 241 242 243 244 245 251 Spill- 286 287 .... Site Plan During Excavation — Plasticity 288 290 292 293 297 299 300 301 Number of the Impervious Zone 302 255 —Sections Location of Instrumentation — Plan 256 Installation of Piezometer 257 261 Canyon Debris Barrier Cleghorn Canyon Debris Barrier San Bernardino Tunnel Approach Channel Access Tunnel and Drainage Gallery Plan Access Tunnel and Drainage Gallery Profiles and 262 Spillway 312 263 Perforated Drain Pipes in Spillway Chute 313 264 Shear Keys in Spillway Chute 314 265 Outlet 266 General Arrangement of Gate Chamber 267 Inlet 268 Flume and Chute 258 259 260 304 305 Tubing 306 Miller — Works— Plan Works— Plan and Profile 307 308 309 310 Sections.... 311 316 317 and Profile 318 319 269 Initial 270 Control Schematics 325 271 Embankment Construction 326 272 Compacting Zone Material Performing Field Density Test on Zone Zone 3 and 4 Material Zone 5 Embankment Shell Material 273 274 275 Reservoir Filling 319 328 1 3 Material 328 329 329 FIGURES—Continued Figure Page Number Dome 276 Rock Bolts 277 Placing Concrete in 278 Location in Works Gate Chamber Gate Chamber of Outlet 332 333 279 — Perris Dam and Lake Perris Aerial \'iew — Perris Dam and Lake Perris 280 Area-Capacity Curves 341 281 Embankment Plan Embankment Sections Embankment Instrumentation 342 347 285 Works— Plan and Profile Outlet Works— Plan and Profile 286 Outlet 351 287 Works Tower Outlet Works Delivery 288 Spillway 289 Spillway Rating Curve 290 Location of Borrow Areas and Perris 291 Excavation 292 282 283 284 Map 346 350 Facilities Profile, 339 343 Inlet — Plan, 338 352 and Sections 354 355 Dam Site 357 Clay Borrow Area 358 Excavation in Lake Borrow Area Rock Production 358 359 298 Embankment Construction Activity Pneumatic Roller on Embankment Zone Tower Concrete Placement Tower Outlet Portal Outlet Works Delivery Manifold 299 Concrete Placement 293 294 295 296 297 in in 359 2 Spillway 360 361 362 362 362 — Pyramid Dam and Lake — Pyramid Dam and Lake Map 300 Location 301 Aerial \'iew 302 Dam 303 Area-Capacity Curves 368 304 370 305 Embankment Sections Embankment Plan 306 Interim 307 Interim 308 Exploration Adits 309 364 365 366 Site Plan 371 Dam — Plan, Sections, and Details Dam — Sections and Profile —Section and Details Diversion Tunnel — Plan and Profile 372 373 376 377 Intake 378 311 Tower Valve Chamber 312 Outlet Works Rating Curves 380 313 Air Shaft 381 314 8-Inch-Diameter Fixed-Cone Dispersion \'alve 382 315 36-Inch-Diameter Fixed-Cone Dispersion Valve 382 316 42-Inch-Diameter Shutoff Valve 383 317 Shutoff \'alves and Butterfly Valve 318 General Plan of Spillway 385 319 Spillway Profile 386 320 Spillway Flip Structure During Discharge 387 321 Spillway Headworks Structure 388 322 Interstate 310 5 Embankments 379 — Accumulator System 383 390 FIGURES— Continued Figure ^^S^ Number 329 Old Highway 99 Bridge Bents Uncovered in Downstream Shell Area of Dam Shaping Excavation on Right Abutment Presplit Face of Shaping Area on Right Abutment Air-Water Jet Cleanup of Foundation Dump Truck Used for Embankment Material Hauling Rear-Dump Rock Wagon Used for Embankment Hauling Spreading and Compacting of Contact Material on Foundation 330 Rolling of Impervious 331 336 Compacting Pervious Material With 10-Ton Vibratory Prefabricated Steel Form Used for Spillway Walls Concrete Placement in Spillway Headworks Invert Concrete Placement in Spillway Chute Slab Location Map Castaic Dam and Lake Aerial View Castaic Dam and Lake 337 Site Plan 406 338 Area-Capacity Curves 408 339 Diversion Tunnel 340 Diversion Tunnel 341 High Intake-Shaft Intersection Diversion Tunnel Intake Structure Outlet Works Energy Dissipator 323 324 325 326 327 328 332 333 334 335 342 343 344 345 393 393 393 394 395 395 396 396 Fill — — — Plan and Profile — Plan and Profile Roller.. 397 399 399 399 404 405 410 (Continued) Embankment Plan Embankment Sections 411 413 414 415 416 417 347 General Plan and Profile of Spillway Spillway and Stilling Basin 348 Spillway Rating Curve 349 Outlet 350 Outlet Works 424 351 Outlet Works 425 346 Works— Plan 420 421 421 and Profile 423 352 — Plan and Profile (Continued) — Low Intake Tower Outlet Works— High Intake Tower 353 Access Bridge 427 354 High Intake Tower and Access Bridge 428 355 429 357 Stream Release Facility Outlet Works Stream Release General Plan of Turnouts 431 358 Outlet Works Turnouts 432 359 Instrumentation 360 Castaic 356 430 —Plan and Section 367 Lagoon Control Structure Sections Castaic Lagoon Control Structure Erosion Control Castaic Lagoon Control Structure Single-Line Diagram Intake Tower Single-Line Diagram Stream Release Facilities Butterfly Valve Assembly Port Valves Hydraulic Scheme Low Intake Gate 368 Low 361 362 363 364 365 366 — — — — Intake Sluiceway 426 434 435 436 437 438 439 441 442 443 444 FIGURES— Continued Figure Number Page 371 — ElevaGeneral Arrangement of Tower Mechanical Features— Elevation and Plan (Continued) General Arrangement of Tower Mechanical Features— Plan and 372 Tower Crane 448 373 20-Ton Polar Bridge Crane 450 374 General Arrangement of Bulkhead Gate 451 375 General Arrangement of Bulkhead Gate and Lifting Beam 376 General Arrangement of Bulkhead Gate, Thimble Seal 377 Guide Turnout 378 General Plan of Stream Release and Turnouts 379 380 Stream Release Facility Hydraulic Schematic 381 Foundation Exploration Trench 382 Flood 383 Dam 384 Block Slide 385 Dam Under 386 388 Abutment Grouting Through Embankment at Left Abutment White Lines Show Limits of Core Zone Scraper Spreading First Load of Embankment in First Approved 389 Loading of Pervious Borrow 390 Soil-Cement Batch Plant 466 391 Spreading Soil-Cement 466 392 466 396 Compacting Soil-Cement Downstream Cobble Slope Protection East Abutment Boat Ramp Concrete Placement High Intake Tower High Intake Tower Bridge Under Construction 397 Low 468 369 370 General Arrangement of tion and Plan Tower Mechanical Features Jib Plate, 452 and 453 \'alve Damage — Hydraulic Schematic to 455 456 —Plan and Sections 457 458 460 Lake Hughes Road Bridge 461 Beginning of Work Site at at 461 Right Abutment Construction 462 — \'iew Across Dam Toward Left Abutment 394 395 462 Excavating Slide Area at Left 463 — Dam 393 446 447 Section 387 445 Foundation Area 464 at Elizabeth Canyon — Intake 463 Tower 465 467 467 467 468 398 General \'iew of Penstock Under Construction 399 Tunnel Penstock 468 400 Spillway Stilling Basin and Chute Excavation 469 401 Spillway Construction 402 Castaic Lagoon Control Structure 468 470 471 TABLES Number 1 Statistical 2 Statistical Summary of 20 Completed Reservoirs and Their Dams Summary of Frenchman Dam and Lake — Frenchman 3 Major Contract 4 Statistical 5 Major Contract 6 Statistical 7 Major Contract 8 Statistical 9 Major Contracts Summary — Antelope Summary Dam Dam Dam of Antelope Summary 32 40 Dam and Lake Davis Dam Dam and Lake Oroville of Oroville —Oroville Dam and Summary 24 and Lake 48 of Grizzly Valley —Grizzly Valley Statistical 11 Major Contracts 12 Statistical 13 Statistical 14 Material Design Parameters 56 64 Appurtenances of Thermalito Diversion 10 115 Dam 143 —Thermalito Diversion Summary Summary of Thermalito of Thermalito 1 14 Dam Forebay Dam and Forebay Afterbay Dam and Afterbay .. 148 160 160 16 —Thermalito Forebay and Afterbay Dams Data for Gates and Hoists —Thermalito Afterbay Major Contracts— Thermalito Forebay, Afterbay, and Power Ca- 17 Statistical 18 Material Design Parameters 207 19 Major Contract 208 20 Statistical 21 Material \5 Summary of Clifton Court Forebay 202 —Clifton Court Forebay —Clifton Court Forebay Dams and Reservoir Design Parameters — Bethany Dams Summary 219 of Bethany — Bethany 221 30 Dam and Bethany Dams Statistical Summary of Del Valle Dam and Lake Del Valle Material Design Parameters — Del \'alle Dam Major Contract — Del Valle Dam and Reservoir Compaction Data — Del Valle Dam Statistical Summary of San Luis Dam and Reservoir Statistical Summary of O'Neill Dam and Forebay Statistical Summary of Los Banos Detention Dam and Reservoir Statistical Summary of Little Panoche Detention Dam and Reser- 31 Statistical 23 24 25 26 27 28 29 173 185 nal 22 169 Major Contracts Forebay .... 235 242 246 257 261 274 274 275 275 voir Dam and Silverwood Lake 294 298 34 Design Earthquake Accelerations Cedar Springs Dam Complex Material Design Parameters Cedar Springs Dam Major Contracts Cedar Springs Dam and Appurtenances 35 Statistical 36 Material Design Parameters 37 Features of Performance Monitoring System 38 Lake Perris Major Contracts 39 Statistical 40 Material Design Parameters 41 Major Contracts 42 Statistical 43 Statistical 44 Material Design Parameters 45 Major Contracts 32 33 Summary of Cedar Springs — — — Summary of Perris Dam 326 340 and Lake Perris — Perris Dam 303 344 — Perris Dam and -^45 — Perris Dam Summary Dam 367 and Lake — Pyramid Dam — Pyramid Summary Summary 356 of Pyramid 374 Dam 392 of Elderberry Forebay of Castaic Dam Dam and Forebay and Lake —Castaic Dam — Castaic Dam and Appurtenances .. 407 408 415 459 State of California The Resources Agency DEPARTMENT OF WATER RESOURCES Ronald Reagan, Governor Norman Jr., Secretary for Resources John R. Teerink, Director Robert G. Eiland, Deputy Director Robert B. Jansen, Deputy Director Donald A. Sandison, Deputy Director B. Livermore, DIVISION OF DESIGN Clifford J. AND CONSTRUCTION Division Engineer Cortright John W. Keysor Howard H. Eastin DIVISION OF Thomas H. T. Morrow Chief, Design LAND AND RIGHT OF WAY Chief, Division of DIVISION OF OPERATIONS H. G. Dewey, Jr. James J. Doody Branch Branch Chief, Construction Land and Right of Way AND MAINTENANCE Division Engineer Deputy Division Engineer State of California Department of Water Resources ' CALIFORNIA WATER COMMISSION IRA J. CLAIR CHRISMAN, A. HILL, T 'ice Chairman, Visalia Chairman, Redding Mai Coombs Ray W. Ferguson Garberville Graham Moses Nelson San Diego Firebaugh San Pablo Northridge Ernest R. Nichols Ventura Ralph Clare E. Ontario W. Jones William Samuel P. B. Orville L. Abbott Executive Officer znA Chief Engineer Tom Y. Fujimoto « k, j, ^ jj^ '.. Assistant Executive Officer i; AUTHORS OF THIS VOLUME George A. Lineer Donald H. Babbitt Gordon W. Dukleth Senior Engineer, Water Resources Dams and Canals Unit, Civil Design Section Division Engineer, Division of Safety of Robert C. Gaskell Chief, Engineering Services Section, Chief, Dams Design Branch Construction Supervisor John H. Lawder John W. Marlette Preston E. Schwartz Chief, Project Gene L. Anderson Alfred J. Castronovo H. John Garber Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Construction Office Manager Construction Management Supervisor Construction Supervisor Associate Engineer, Water Resources Associate Engineer, Water Resources Associate Engineer, Water Resources Water Resources Engineering Associate Construction Supervisor Water Resources Engineering Associate Construction Supervisor Mechanical Construction Supervisor Leon M. Hall Cortland L. Lanning Samuel J. Linn, Jr. George C. Myron Fleming E. Peek Donn Stafford J. Henry E. Lorimer Ted E. Struckmeyer E. Erikson Rowe James L. Zeller Curtis A. Canevari Dale E. Martfeld *] Geology Section Water Resources Principal Engineer, (Retired) Herman Neibauer William C. Baer Menzo D. Cline Gale G. Hannum John A. Hartung Donald E. Wiles EDITOR Arthur C. Gooch Chief, Program Analysis Office IN THE DESIGN AND CONSTRUCTION OF THESE PROJECT WORKS, POSITIONS OF MAJOR ENGINEERING AND RELATED RESPONSIBILITY WERE HELD BY: nos H. Adams Adams )bert F. G. Anderson larles Anderson Arnold Arnold ;ne L. thur B. loyd S. »rge D. Atkinson, Jr tenn L. Atkinson jnald H. Babbitt »ger A. Baker trvey O. Banks G. Barrett ith hn L. Baugh bn H. Beaver iss D. Billings maid P. Bisio Blohm ,rry L. P Brock rold iin A. Buchholz J. Bunas Iliam E. Busby lester A. Bush n E. Bussell ilson M. Cantrell in A. Cape thur vid B. Carr in Carrillo H. Carter _,/de P. Cass larles fin Castain fred Ux Castronovo J. Champ A. H. Chan l.'fbert p L. Chatterly I'lrold F. k mold T. Cook J Cortright itford • Jin W. Cowin H. Davies Davis J. G. Dewey, Jr. Dickinson J. Henry Fredericks Norman K. Paul H. Gilbert Austin E. Gilligan Raymond D. Gladding Alfred R. Golz6 Bernard B. Gordon Seymour M. Gould Leemon C. Grant Edgar L. T. Dodds I. Donald Doody J. Drake W. Dukleth tanklin E. lirdon !,inuel S. -(idrew F. Dulberg Dywan Horn T Easterday l)ward H. Eastin Jbert Ehrhart Iben G. Eiland 'jilliam W Iliam J. Ellis Iroy F. Eriksen 'I Calvin M. Irvine Joey T. Ishihara Ernest C. James Laurence B. James Robert B. Jansen E. Jaskar Arnold W. Johnson Richard W. Johnson Takashi T. Kamine John W. Keysor Frank C. Kresse George H. Kruse Edward J. Kurowski, J. E. Stephen E. Smith Ross G. Sonneborn Donn Moellenbeck, Mooner Alexander S. Nadelle Harold Nahler Don H. Nance Herman Neibauer Jerome S. Nelson Theodore Neuman Philip M. Noble Gene M. Norris Harry L. O'Neal AlanL. O'Neill John E. O'Rourke Stafford Steinar Svarlien Fay H. Sweany Jr. Mark A. Swift John R. Teerink Donald P. Thayer Medill P. Theibaud Robert S. Thomas Harrison M. Tice Albert C. Torres L. O. Transtrum Theodore W. Troost Lewis H. Tuthill Owen I. L'hlmeyer Austin V'arley Arthur C. \'erling John C. X'ernon Jack D. Walker L. Papathakis Wilferd W. Peak Fleming E. Peek Charles W. Perry X'ernon H. Persson Carleton E. Plumb Joseph D. Walters William K. Warden William E. Warne Carl A. Werner Ray L. Whitaker Addison F. Wilber Donald E. Wiles Kenneth G. Wilkes James V. Williamson E. Owen Wineland Marian Pona Jeff A. George E. Purser Joseph A. Remley Robin R. Reynolds Eldred A. Rice Roy C. Wong Dee M. Wren Gordon Jack G. Wulff A. Ricks Paul C. Ricks Raymond C. Richter Raymond L. Ritter Ted E. Rowe Jr. J. Donald C. Steinwert Malcolm N. Stephens Elmer W. Stroppini Henry E. Struckmeyer Menuez Andrew J. Morris Thomas H. T. Morrow George C. Myron Donald George E. Houston Ralph E. Houtrouw Herbert C. Hyde Ade A. W. Burt Shurtleff Cecil N. Smith R. Mitchell Raymond W. Oleson Hoffman Kenneth Jnes Sr. Norman W. Hoover Jack E. diaries Hawkins Edward Henry J. Jr. Lucas S. Albert John Richard L. Hearth Charles \'. Heikka A. John E. Schaffer Walter G. Schulz Preston E. Schwartz James B. Scott James G. Self Joseph H. Sherrard Clyde E. Shields Lyons Alexander Mailer John W. Marlette Calvin M. Mauck Fred L. McCune Robert L. McDonell Donald H. McKillop Manuel Mejia Leo Meneley Don Robert G. W. Harder Robert E. Harpster John A. Hartung Harold H. Henson, Marcus O. Hilden Vincent D. Hock Robert E. Rutherford Ray S. Samuelson Joseph R. Santos Robert K. Miller Grider Carl A. Hagelin Leon \4. Hall William D. Hammond J. \'. Clifford Edward Edward R. Grimes John P. Grogan David J. Gross Marvin Eugene M. Lill Samuel J. Linn, Mark Gadway H. John Garber Robert C. Gaskell William R. Gianelli Lvere tV. rge J. LaChapelle Robert F. Laird Cortland C. Lanning John H. Lawder Frank \'. Lee Carl G. Liden V'ictor Harald D. Frederiksen Wallace D. Fuqua lul 1 I Christy Coe Shirl A. Evans John K. Facey Ray N. Fenno Herbert B. Field John W. Flynn Samuel Fong Harold E. Russell Robert E. Wright Robert H. Wright Burton O. Wyman Richard A. Young James L. Zeller Kolden L. Zerneke AUTHORS OF THIS VOLUME George A. Linear Donald H. Babbitt Gordon W. Dukleth Senior Engineer, Water Resources Dams and Canals Unit, Civil Design Section Division Engineer, Division of Safety of Robert C. Gaskell Chief, Engineering Services Section, Chief, Dams Design Branch Construction Supervisor John H. Lawder John W. Marlette Preston E. Schwartz Chief, Project Gene L. Anderson Alfred J. Castronovo H. John Garber Leon M. Hall Cortland L. Lanning Samuel J. Linn, Jr. Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Senior Engineer, Water Resources Construction Office Manager Construction Management Supervisor Construction Supervisor Associate Engineer, Water Resources Associate Engineer, Water Resources Associate Engineer, Water Resources Water Resources Engineering Associate Construction Supervisor Water Resources Engineering Associate Construction Supervisor Mechanical Construction Supervisor George C. Myron Fleming E. Peek Donn Stafford J. Henry E. Lorimer Ted E. Struckmeyer E. Erikson Rowe James L. Zeller Curtis A. Canevari Dale E. Martfeld Herman Neibauer William C. Baer Menzo D. Geology Section Water Resources Principal Engineer, (Retired) Cline Gale G. Hannum John A. Hartung Donald E. Wiles EDITOR Arthur C. Gooch Chief, Program Analysis Office IN THE DESIGN AND CONSTRUCTION OF THESE PROJECT WORKS, POSITIONS OF MAJOR ENGINEERING AND RELATED RESPONSIBILITY WERE HELD BY Shirl A. Evans John K. Facey Ray N. Fenno Herbert B. Field Flynn John Samuel Fong Amos H. Adams Robert F. Adams Charles G. Anderson Gene Anderson L. Arthur B. Arnold Floyd S. Arnold George D. Atkinson, Glenn L. Atkinson Donald H. Babbitt Roger A. Baker Harvey O. Banks Keith G. Barrett W Jr. ohn L. Baugh ohn H. Beaver Ross D. Billings Ronald P. Bisio Harry L. Blohm Harold P. Brock ohn A. Buchholz Arthur J. Bunas William E. Busby Chester A. Bush jBen E. Bussell Wilson M. Cantrell (ohn A Cape David B. Carr ohn Carrillo Charles H. Carter Clyde P. Cass ohn Castain Alfred Castronovo J. Vlax A. Champ Herbert H. Chan lay L. Chatterly Harold F. Christy lack Coe Harold T. Cook Clifford J. Cortright lohn W. Cowin Paul H. Davies Devere J. Davis H. G. Deviey, Jr. im \'. Dickinson .jeorge T. Dodds Charles I. X'ictor J. LaChapelle Robert F. Laird Cortland C. Lanning John H. Lawder Frank \'. Lee Carl G. Liden Donald lames J. Doody franklin E. Drake Cordon W. Dukleth 5amuel S. Dulberg lAndrew F. Dywan William T. Easterday Howard H. Eastin Robert W. Ehrhart ilobert G. Eiland William J. Ellis Lerov F. Eriksen J. Henry Fredericks Harald D. Frederiksen Wallace D. Fuqua Norman K. Don Grider John Robert G. W. Harder Robert E. Harpster John A. Hartung Hawkins Richard L. Hearth Charles \'. Heikka Edward Henry Harold H. Henson, Marcus O. Hilden Vincent D. Hock A. J. Sr. Mooner Andrew J. Morris Thomas H. T. Morrow George C. Myron Alexander S. Nadelle Harold Nahler Don H. Nance Herman Neibauer Jerome S. Nelson Theodore Neuman Philip M. Noble Gene M. Norris Harry L. O'Neal Alan L. O'Neill John E. O'Rourke Donald George Horn E. Owen L. Papathakis Wilferd W. Peak Fleming E. Peek Charles W. Perry Vernon H. Persson Carleton E. Plumb Kenneth E. Houston Ralph E. Houtrouw Herbert C. Hyde Calvin M. Irvine Joey T. Ishihara Ernest C. James Laurence B. James Robert B. Jansen Ade J. E. Raymond W. Oleson Hoffman Norman W. Hoover Jack E. Stephen E Smith Ross G. Sonneborn Donn Marian Pona E. Jaskar Arnold W. Johnson Richard W. Johnson Stafford Steinar Svarlien Fay H. Sweany Jr. Mark A. Swift John R. Teerink Donald P. Thayer Medill P. Theibaud Robert S. Thomas Harrison M. Tice Albert C. Torres L. O. Transtrum Theodore W. Troost Lewis H. Tuthill Owen I. L'hlmeyer Austin Varley Arthur C. X'erling John C. Vernon Jack D. Walker Joseph D. Walters William K. Warden William E. Warne Carl A. Werner Ray L. Whitaker Addison F. Wilber Donald E. Wiles Kenneth G. Wilkes James \'. Williamson Jeff A. Wineland George E. Purser Joseph A. Remley Robin R. Reynolds Eldred A. Rice Roy C. Wong Dee M. Wren Gordon A. Ricks Jack G. Wulff Takashi T. Kamine Paul C. Ricks John W. Keysor Frank C. Kresse George H. Kruse Edward J. Kurowski, Raymond C. Richter Raymond L. Ritter Ted E. Rowe Jr. J. Donald C. Steinwert Malcolm N. Stephens Elmer W. Stroppini Henry E. Struckmeyer Menuez Moellenbeck, Rutherford W. Burt Shurtleff Cecil N. Smith R. Mitchell Albert Carl A. Hagelin Leon M. Hall William D. Hammond J. Jr. Lucas Lyons Alexander Mailer John W. Marlette Calvin M. Mauck Fred L. McCune Robert L. McDonell Donald H. McKillop Manuel Mejia Leo Meneley A. Samuelson S. John E. Schaffer Walter G. Schuiz Preston E. Schwartz James B. Scott James G. Self Joseph H. Sherrard Clyde E. Shields Robert K. Miller Edward R. Grimes John P. Grogan David J. Gross Marvin \'. E. Ray Joseph R. Santos S. Edward Seymour M. Gould Leemon C. Grant L. Clifford Mark Gadway H. John Garber Robert C. Gaskell William R. Gianelli Paul H. Gilbert Austin E. Gilligan Raymond D. Gladding Alfred R. Golz6 Bernard B. Gordon Edgar Eugene M. Lill Samuel J. Linn, Robert Harold E. Russell Robert E. Wright Robert H. Wright Burton O. Wyman Richard A. Young James L. Zeller Kolden L. Zerneke ABSTRACT The storage facilities Twenty reservoirs and of the State Water Project are discussed in this volume. their associated dams are now in operation. They are located throughout the Project over a distance of about 650 miles. Three additional dams will be constructed in the future to complete all authorized storage facilities; however, these are not included in the discussion of the individual storage facilities presented in this volume. Five of the existing dams were designed and constructed by other agencies: four by the U. S. Bureau of Reclamation as part of the Federal-State Joint-Use Facilities and one by the City of Los Angeles Department of Water and Power. All of these facilities constructed by others were partially funded by the Department of Water Resources, and the Department also is their operator, except for the small forebay constructed by Los Angeles Department of Water and Power. The more interesting and unique aspects of the design and construction details of each dam are discussed under the appropriate headings. Included are descriptions of site geology, seismicity, embankments, outlet works, spillways, and equipment. The volume is written in the language of engineers and engineering geologists engaged in design and construction acitivities throughout project development. Highly technical discussions and extensive details are avoided in an attempt to interest the largest cross section of readers. Design analyses and alternatives studied generally are included whenever they are related to major decisions and unusual physical features. Difficulties which arose during construction or after start of operations also are discussed. These difficulties probably were no greater or less than encountered by others involved in similar major projects. Consulting firms and boards were selected and retained by the Department to provide broad experience and expertise in several areas of project work. Extensive model-testing programs designed to ensure appropriate and economic design were utilized and supervised by the Department. xli An "lope Laka rharmama Fatwa; Dun: Ra luau z?Rasarvair Abby Bridal Raurvair A - ran: man ?Laka Laka avts Tharmalira A I nrbay_/ \Lalu Tharnwmo Divarsian Dan, Faam" Rinr is? md Fish Barriar Dam Nar?v Bay Aquaduc? Paripharal Canal \Cli?m Cour! Fanbay - . Barhany Dams and Rasarvalr Laka Dal Sour/v Bay Val/a ,0'Naill Farabay Aquaduc! /San Luis Rasarvair . Laa Banay Ruuvair - Lin/a Panacha CA I ORN A Rasarvair Coastal Branch 5:35;, /Eldalbarry Farabay Pyramy Laka (Ca: Iaic Lalu vaad \Laka data Farris Figure 1. Location Map?State Water Proiect Reservoirs xlii — CHAPTER 1 Overview There are 20 completed reservoirs in the State Water Project, the locations of which are shown on Figure I. Fifteen were built and are operated by the Department of Water Resources, and four (San Luis Joint-Use Facilities) were built by the U.S. Bureau of Reclamation and now are operated by the Department. The last of the 20 completed reservoirs. Elderberry Forebay, was built and is operated by the City of Los Angeles Department of Water and Power as part of the Pyramid-Castaic power development. Table 1 presents a brief statistical summary of the 20 completed reservoirs and their dams, discussed in this volume. The first Frenchman project in the all of which are dams to be constructed were Upper Feather River watershed and Bethany Forebay at the head of the South Bay .Aqueduct. Both prime contracts were let in 1959. Orothe largest dam of the Project, was started and reservoir storage began in November 1967. Other work on the Project proceeded southward during the 1960s and early 197(is with Pyramid, the last dam in the initial phase of the Project, completed ville in Dam, 1962, in early 1974. Virtually all of the project yield of 4,230,000 acre- TABLE 1 . Statistical Summary I. GENERAL annually comes from two sources: the Feather River watershed above Oroville Dam, and surplus winter and spring runoff from other watersheds tributary to the Sacramento-San Joaquin Delta. Surplus water in the Delta is pumped into San Luis Reservoir for summer and fall releases. Thus, Oroville Dam and San Luis Dam are the two key conservation features of the State Water Project. Nine of the existing 20 reservoirs are involved in the generation of power, with all but one utilizing pumped storage. In the Oroville Division, two pumping-generating plants, Edward Hyatt Powerplant underground in the left abutment of Oroville Dam and Thermalito Powerplant, involve four reservoirs Lake Oroville, Thermalito Diversion Pool, Thermalito Forebay, and Thermalito Afterbay. Pumpinggenerating plants also are located between San Luis Reservoir and O'Neill Forebay and between Pyramid Lake and Elderberry Forebay. The ninth reservoir, Silverwood Lake, is the forebay for Devil Canyon Powerplant. Pyramid, Castaic, and Silverwood Lakes and Lake Perris are large reservoirs located near the metrofeet politan areas of Southern California, where water supplies primarily are imported. The three aqueducts of 20 Completed Reservoirs and Their Dams which supply water Owens fornia, to Southern California (Cali- Valley, and Colorado River Aque- ducts) cross the San Andreas fault system and likely could be disrupted, at least temporarily, by fault movement. In view of this, these four reservoirs were constructed as large as practicable to provide a reserve water supply should such an event occur. Two reservoirs, Oroville and Del Valle, are drawn down prior to the flood season to create an adequate storage capacity to control downstream floods. Costs allocated to flood control were borne by the Federal Government. Although incidental flood control benefits accrue to many of the other reservoirs in the sys- tem, no federal flood control payments were made. Substantial recreation benefits are derived from reservoirs throughout the Project, with the Upper Feather River reservoirs built primarily for this purpose. Recreation use, in general, has greatly exceeded predictions, and onshore recreation developments have lagged the demand. Additional reservoirs, Abbey Bridge and Dixie Refuge in the Upper Feather River watershed and Buttes in the Mojave Division, are planned for future construction. The first two will be used primarily for recreation and the third to regulate water deliveries. The following sections briefly describe the dams and reservoirs and relate them State Water Project. to the remainder of the Upper Feather River Division Beginning with the northernmost features of the Project, three of five authorized reservoirs (Figure 2) ! i_^- 1^, r CH. iM^nT^. '^^ LAKE ^''^^==^- CRESCcN MILLS ,0\'-' ' ->'f II A >-»!ii 1 OUINCY V I '""t*>'-:i.^ M -. Figure 2. Upper Feather S River Division i x;===;=::::!«' l.OVaLTON / , ' - ^ ^ ° CK V LAKE OROVILLE ELEV 900' \ OROVILLE DAM. Edward hvaTt CK VII THERMALITO FOREBAY FISH HATCHERY '^THERMALITO DIVERSION DAM Figure 3. have been completed: Frenchman Lake, Antelope Lake, and Lake Davis. All five reservoirs are, or will be, located on the upper tributaries to the Feather River a river system with a drainage area in excess of 3,600 square miles above Oroville Dam. The three completed reservoirs have a combined storage capacity of 162,414 acre-feet and provide for local irrigation, recreation, and incidental flood control. All of the dams are of earthfill construction and vary in height from 120 to 139 feet. Frenchman Dam, the largest of the dams, is a 139-foot-high earth embankment containing 537,000 cubic yards of material. The largest reservoir in the group is Lake Davis, which has a gross capacity of 84,371 acre-feet. — Oroville Division About 90 miles downstream on the Feather River at and about 100 miles upstream from the Sacra- Oroville Oroville Division is the Oroville Division (Figure 3 ) Included in this division are Oroville Dam and the Oroville-Thermalito power complex. Oroville Dam, one of the two principal conservation features of mento-San Joaquin Delta . the Project, impounds 3, 537, .577 cluded in this storage capacity acre-feet of water. Inis provision for flood The reservoir has a surface area of 15,805 acres and a shoreline of 167 miles. control. embankment dam, 80,000,000-cubic-yard the highest earthfill dam in the United States at the present time (1974), rises 770 feet above streambed excavation and has a crest length of 6,920 This which is feet. Power at Oroville Dam is produced by the Edward Hyatt Powerplant and the Thermalito power facilities, which in turn encompass a diversion dam, a power canal, a forebay, and an afterbay. Edward Hyatt Powerplant underground in the .'eft abutcontains three conventional generators and three motor-generators coupled to Francis-type reversible pump-turbines. The latter units provide for off-peak pumped-storage operations. Releases from Edward Hyatt Powerplant are diverted from the Feather River by the 143-foot-high Thermalito Diversion Dam, a concrete gravity overpour structure with a 560-foot-long radial gate crest section. These releases pass at a maximum rate of 16,900 cubic feet per second (cfs) through the 10,000foot-long Thermalito Power Canal and Thermalito is located ment of Oroville Dam. It to Thermalito Powerplant. The Thermalito Diversion Pool, Power Canal, and Forebay have a common water surface to accommodate flow reversals Forebay pumped-storage operation. Thermalito Forebay Dam is a 5,900-foot-long embankment with a maximum height of 91 feet. The powerplant intake structure is an integral part of the Dam. This plant is equipped with one Kaplan turbine and three pump-turbines and operates under a static for the 1 head of 100 feet. Thermalito Afterbay has a gross capacity of 57,041 acre-feet and stores plant discharges for the pumpedstorage operation as well as reregulates flows for return to the Feather River. The afterbay dam is a 42,000-foot-long earth structure with a maximum height of 39 feet. Migrating salmon and steelhead blocked by the development are diverted from the River into the Feather River Fish Hatchery by the Fish Barrier Dam, located '/j rnile downstream of Thermalito Diversion Dam. This 91 -foot-high, concrete, overpour structure is discussed in Volume VI of this bulletin. North San Joaquin Division and South Bay Aqueduct The initial and northernmost nia Aqueduct, designated the reach of the Califor- North San Joaquin is CLIFTON COURT FOREBAY' ^AVWARD '. INTAKECHANNELt C DELTA PUMPING PLANT BETHANY RESERVOIR^ SOUTH BAY PUMPING PLANT DYER CANAL .IVERMORE TUNNEL\ yPIPELINE CANAL BRANCH PIPELINE AND PUMPING PLANT DEL VALLE N SAN JOAOUIH CH. X / Figure 4. Divi- 68 miles long (Figure 4). Principal features consist of Clifton Court Forebay in the Delta, the Delta Fish Protective Facility, 3 miles of unlined insion, South Bay Aqueduct and Part of North Son Joaquin Division DIVISION 1 1 I 1 I ; Del reach decreases from 10,300 cfs at at its terminus. by agreement with its head to 10,000 cfs Water released from Oroville Dam flows down the Feather and Sacramento Rivers, and the surplus waters in the Sacramento-San Joaquin Delta then are diverted into the California Aqueduct at Clifton Court i I . j [ 1 : j : I I i ' ' I I ' ' \'alle Dam, also provides flood control for Livermore X'alley and conserves local runoff. This embankment structure contains 4,150,000 cubic yards of earth take channel, Delta Pumping Plant, Bethany Reservoir, and 64 miles of coprrete-lined canal and appurtenant structures. The Division terminates at O'Neill Forebay. The design capacity of this aqueduct materials. The conservation function was established a local agency and project operation. Local runoff is is stored incidental to when N SAN JOAQUIN SAS LUIS RESERVOIR project DIVISION O'NEILL FOREBAY Forebav. This forebay provides storage for off-peak pumping at Delta Pumping Plant and minimizes any adverse effects on existing Delta channels by diverting and storing large amounts of water at high tide. It has a surface area of 2,109 acres. The water is diverted from the Delta into the Forebay from adjacent Delta waterways, namely Old River and West Canal, and is regulated by an intake structure with five automatically controlled radial gates. The water eventually will be conveyed to Clifton Court Forebay through the planned 43-mile-long Peripheral Canal. This unlined canal will start at the Sacramento River 18 miles south of the City of Sacramento and will skirt the eastern perimeter of the Delta. It will be hydraulically isolated from the Delta channels and will connect to the east side of the Fore- rc HJci bay. Bethany Forebay Dam was included in the initial construction of the South Bay facilities. The 890-acrefoot forebay, formed by the 119-foot-high 300,000-cubic-yard embankment, was used to provide operational flexibility as well as conveyance capability. Initially, water was supplied to the South Bay Aqueduct from the federal Delta-Mendoia Canal through a small unlined canal. An interim pumping plant at the toe of the Dam lifted the water from the unlined canal into the forebay. South Bay Pumping Plant, located on the forebay, lifts the water 545 feet to the head of the 42-mile-long South Bay Aqueduct. The plant has since been expanded to the present 330-cfs capacity. During construction of the California Aqueduct and Delta Pumping Plant in the North San Joaquin Division, the forebay was expanded into the present Bethany Reservoir. Four embankments similar to the Forebay Dam were constructed, a channel was excavated to connect two sections of the Reservoir, and the California Aqueduct was cut into the north and south ends of the Reservoir. The Reservoir functions as a 1 '/2-mile reach of canal and provides operational flexibility for Delta Pumping Plant, located 2 miles to the north. Regulatory storage for South Bay Aqueduct now is provided in the 100-acre-foot Patterson Reservoir and the 77,106-acre-foot Lake Del Valle (Patterson Reservoir is discussed in Volume II of this bulletin). Lake Del \'alle is located on Arroyo Del \'alle near the midpoint of the South Bay Aqueduct. Project water is pumped into Lake Del \'alle through a and released from it branch pipeline and Del \'alle Pumping Plant. The Lake, formed by 235-foot-high ''CALIFORNIA G s :;\- 120-cfs Figure 5. San Luis Di> AQUEDUCT operations permit and is released into the stream channel as requested by the local agency. San Luis Division The 106-mile-long reach, designated the San Luis Division, constitutes the Federal-State Joint-Use Facilities (Figure 5). It includes, among other feaSan Luis Dam and Reservoir and appurtenant pumping-generating facilities. This entire division was designed and built by the U.S. Bureau of Reclamation and is operated by the Department of Water Resources on a cost-sharing basis, which is discussed in Chapter XI of this volume. San Luis Reservoir, located at the head of this reach, tures, provides 2,038,771 which acre-feet 1,067,908 acre-feet is of off-line storage, of the State's share. The main dam is an earthfill structure 385 feet high with a crest length of 18,600 feet. A total of 77,645,000 cubic yards of material was used in its construction. Water delivered to O'Neill Forebay through the California Aqueduct and Delta-Mendota Canal is pumped during off-peak periods into San Luis Reservoir. On-peak power is generated from releases made through the eight reversible units in the San Luis Pumping-Generating Plant, located at the toe of the main dam. O'Neill Forebay, with a gross capacity of 56,426 acre-feet, serves as a regulation pool for the San Luis Pumping-Generating Plant and also as a gravity diversion pool for flows continuing south in the California Aqueduct. The reservoir has a surface area of 2,700 • The forebay dam required 3,000,000 cubic yards of material and has a maximum height of 88 feet and a crest length of 14,350 feet. The distance across the Forebay in the direction of the flow of the California acres. Aqueduct is about 3 miles. Los Banos and Little Panoche Detention Dams located south of San Luis Reservoir protect the Aqueduct, the Delta-Mendota Canal, and other improvements from floodflows. Los Banos Detention Dam also provides a 470-acre recreation pool. materials, respectively. Because of en route deliveries, the flow capacity of the California Aqueduct through the San Luis Division decreases from 13,100 to 8,350 cfs, 7,050 cfs of which is for the State Water Project. Dos Amigos Pumping Plant, located 16 miles south of O'Neill Forebay, provides a 113-foot lift in the Aqueduct. South San Joaquin and Tehachapi Divisions The last reach of the California Aqueduct in the Central \'alley, designated the South San Joaquin Division, is 121 miles long and primarily is canal. Three pumping plants (Buena Vista, Wheeler Ridge, and Wind Gap) with a total lift of 956 feet are located within FERNAND Figure 6. this reach. The aqueduct capacity decreases from 8,100 to 4,400 cfs reflecting en route deliveries to water users. Volume I of this bulletin contains a dis- WEST BRANCI ^ reser- contain 2,100,000 and 1,210,000 cubic yards of earth TEHACHAPl DIVISION VENTURA The voirs have a capacity of 34,562 and 13,236 acre-feet, respectively. The Dams are 167 and 152 feet high and Mojave Division ussion of the events which brought about the disparflows between this division and the San Luis )ivision to the north. The next reach of aqueduct, designated the Tehachpi Division, crosses the Tehachapi Mountains. A. D. ty in "dmonston Pumping Plant, located at the northern of the Tehachapi Mountains, has the capability to ift 4,410 cfs nearly 2,000 feet in a single lift through wo 12'/2-foot-diameter, underground, discharge lines. These discharge lines enlarge to a 14-foot diameter bout halfway up the slope. At the top of the lift, these ines are joined by a manifold. Three 2 3 '/2-foot and one 20-foot-diameter tunnels, otaling 7.9 miles in length, are joined by siphons to arry the water through the summit region of the lase fehachapis. The longest tunnel, 4% miles, is the 20oot-diameter Carley V. Porter Tunnel. The longest iphon, the 2,452-foot-long Pastoria Siphon, conveys he water across Pastoria Creek between Tehachapi Tunnels Nos. 2 and 3. It consists of a single, elevated, 92-inch-diameter, steel pipeline designed for 2,680 fs. A similar parallel pipeline is required to bring this each up to ultimate planned capacity. Tehachapi Afterbay, at the southern end of this diision, provides minor regulatory storage to accomnodate flow mismatch between A. D. Edmonston 'umping Plant and the downstream pumping plants. t consists of a concrete-lined, trapezoidal, canal secion, 24 feet deep, over most of its 0.6-mile length. The Branch bifurcates from the California Aqueduct the southern end of the Afterbay. The Afterbay is ,iscusssed in Volume II of this bulletin. Vest t .dojave Division Extending southeasterly from the Tehachapi Afterthe 102-mile-long reach of Aqueduct designated he Mojave Division (Figure 6). The Aqueduct conists of 93.4 miles of concrete-lined canal and a total of .9 miles of pipeline. At the head of this reach, two hutes accommodate a 132-foot total drop in the vertial alignment. Midway along the Division, the Pearilossom Pumping Plant, with a capacity of 1,380 cfs, ifts the water 540 feet, the high point along the entire >ay is California Aqueduct alignment. Silverwood Lake, a 74,970-acre-foot, eservoir, is located at the end of in-line, storage this division. The formed by Cedar Springs Dam, regulates delivries in the system, provides emergency storage of vater for use during aqueduct outages, and furnishes vater-oriented recreation. Cedar Springs Dam is a 7.6nillion-cubic-yard earth and rockfill dam 249 feet ^ake, ligh with ianta . a crest length of 2,230 feet. Ana Division The remaining reach along the California Aquedesignated the Santa Ana Division, is 34 miles luct, ong and terminates Lake Perris, a 13 1,4 5 2 -acre-foot Flows are released from Silver- at .eservoir (Figure 7). vood Lake into the 3.8-mile-long 12 '/-foot-diameter hn Bernardino Tunnel. This high-head pressure tunFlgure 7. Santa Ana Division — nel, with a capacity of 2,020 cfs, is directly connected Canyon Powerplant penstock. The plant, the mouth of Devil Canyon at the southern to the Devil situated at base of the San Bernardino Mountains, is a 119,700- kilowatt installation which operates under a normal static head of 1,418 feet. The penstock, which varies in diameter from 9/2 feet to 8 feet, is an elevated steel pipeline. The Powerplant houses two impulse turbines rated at 81,000 horsepower each and two generators rated at 63,000 kVA each. The Santa Ana Valley Pipeline, which comprises about 28 miles of buried high-pressure pipe 9 to 10 feet in diameter, conveys a flow of 444 cfs to the Project's terminal reservoir in Riverside County. This design flow capacity has been recalculated recently at 469 cfs due to a lowering of the pipeline outlet to Lake Perris. Lake Perris, the terminus of the "main line" California Aqueduct, regulates deliveries and provides emergency storage and recreation. Perris Dam, of zoned earthfill construction, is 128 feet high and has a crest length of over 2 miles. The embankment required 20 million cubic yards of fill. Castaic Powerplant will have a generating capacity of 1,200 megawatts. Six pump-turbines with motorgenerator units are being installed. Companion Unit 7 Powerplant contains a 50-megawatt generator which can be used in the pump-starting process. The plants discharge into the 28,231 -acre-foot Eld-f erberry Forebay, from which the water is either pumped back to Pyramid Lake or released into Castaic Lake immediately downstream of the forebay dam. Elderberry Forebay Dam is a 200-foot-high, 6,000,000cubic-yard, zoned The power embankment. between Pyramid Lake and facilities Castaic Lake are joint-use facilities of the City of Los Angeles and the Department of Water Resources. The City constructed and operates Castaic Powerplant, Unit 7 Powerplant, and Elderberry Forebay. Castaic Dam is a 42S-foot-high earthfill embankment with a crest length of 4,900 feet creating a reservoir with a capacity of 323,702 acre-feet. Approximately 46 million cubic yards of material was used in its construction. Castaic Lake provides operational and emergency storage and water-oriented rec- \ reation. West Branch Division The West Branch originates at Tehachapi Afterbay and extends southerly about 32 miles toward Los Angeles (Figure 8). Water flows by gravity southward from the Afterbay about 1'/^ miles to Oso Pumping Plant. This plant has a capacity of 3,128 cfs against a maximum an indoor-type motor-driven pumps which require a total of 93,800 horsepower. The eight pumping units are manifolded to five 9-footdiameter discharge lines. head of 231 housing eight static installation feet. It is electric the end of the Oso Pumping Plant discharge concrete-lined canal extends 2.7 miles in a southwesterly direction to Quail Lake, a small regulation pool discussed in Volume II of this bulletin. From Quail Lake, the canal continues 2.3 miles to a transi- From lines, a temporary Gorman Creek Improvement The Improvement Facilities, primarily an tion to the Facilities. 8-foot-base-width concrete-lined channel, extend 6 miles to Pyramid Lake, a 171,196-acre-foot, in-line, storage reservoir. To utilize the 740-foot drop upstream from this reservoir, a pipeline will replace the Gorman Creek Improvement and a power plant will be installed with initial operations planned for 1982. Pyramid Dam is a 400-foot-high zoned earth and rockfill embankment, with a crest length of 1,090 feet. From Pyramid Lake, which also functions as a power pool, water is diverted through the 30-foot-diameter 7.15-mile-long Angeles Tunnel to Castaic Powerplant. Maximum flow through the concrete-lined tunnel during periods of peak demand will be 18,400 cfs. A surge tank is located near the downstream portal of the Tunnel. The chamber is 1 20 feet in diameter and 383 feet high, with 158 feet of its height above- ground. Design The Department's staff located in Sacramento de- signed all the storage facilities except those previously credited to the U. S. Bureau of Reclamation or the Los Angeles Department of Water and Power. The same engineers designed or reviewed all significant changes made during the construction process. Appendix A of this volume mentions the consultants and others outside the Department who contributed to the design and construction of the storage facilities. The latest available design techniques were employed, hydraulic model studies were run on all major structures, and extensive, sometimes innovative, exploration and soils-testing programs were conducted. This work is covered in the chapters on the various of this volume includes dams. For example. Chapter discussions of the early application of the finite element technique to the design of the Oroville Dam grout gallery and of the embankment seismic analysis that led to the finite element analysis currently being V used on dams. Construction Construction contracts for storage State facilities of th( Water Project were awarded and administerec accordance with provisions of the State Contrac Act, Sections 14250 to 14424, Government Code, Stat utes of the State of California. The State Contract Ac requires that bids be solicited in writing and that th( contract be awarded to the lowest responsible bidder To comply with the Act, the following procedure in were employed: 1. Prequalification of prospective contractors two-phase prequalification procedure was used t to es _^ TEHACHA Pl MOJA v5 DIVISION TEHA CHA AF TERRA 050 CANAL . 050 PLANT (UPPER I - WEST BRANCH, CALIFORNIA AOUEDUCT I VAL LEY PIPELINE x! . PYRAMID ?5 CANAL SURGE CHAMBER PYRAMID . DAM 8 LAKE CASTAIC HIGHWAY RELOCATMN POWERRLANT 0AM 8 LAKE ELDERBERRY FOREEAY LAKE HUGHES FPOA RELOCATION Figure 8. West Branch Division c ^ OROVILLE PROJECT OFFICE ^« Sacramento PERIPHERAL CANAL NORTH SAN JOAQUIN PROJECT OFFICE NORTH SAN JOAQUIN SOUTH BAY, DIVISION PROJECT OFFICE U.S.B.R. PROJECT vOFFICE ^ SOUTH SAN JOAQUIN PROJECT OFFICE TEHACHAPI DIVISION PALMDALE^ROJECT OFFICE r?P/^ MOJAVE DIVISION WEST BRANCH DIVISION SANTA ANA DIVISION TEHACHAPI -WEST BRANCH^ PROJECT OFFICE Figure 9. 10 Location of Construction Project OfRces tablish qualified bidder lists of those contractors desir- ing to bid. First, if the required financial statement indicated that the contractor had the necessary resources, the request for prequalification was processed further. Second, the contractor's ability was assessed based on the firm's overall experience and other uni- form factors. — Advertisement and award of contracts Public was given once a week for at least two consecutive weeks in a newspaper published in the county in which the project was located and in a trade paper of general circulation in either San Francisco or Los Angeles, as appropriate. A "Notice to 2. notice of a project , Contractors", in each case, was sent to all contractors list of qualified bidders. This document generally described the requirements and extent of the work and indicated the time and place for receiving on the !the bids. Contracts were awarded to the lowest responsible bidder. Responsible bids were those meeting all the conditions of bidding stated in the bidding require- ments and determined to be reasonable compared with the engineer's estimate. in cost when The Department's organization for supervision of construction activities consisted of project offices at selected locations throughout the State and a headquarters construction office located in Sacramento (Figure 9). Each project office was responsible for all project construction work within a particular geographical area and was staffed with construction engineers, inspectors, engineering geologists, and laboratory and other technicians. The headquarters construction office provided administrative and liaison services to the project offices. Factory inspection of materials and equipment to be incorporated in the work was performed by an equipment and materials section of the headquarters construction office. 11 LITTLE LAST CHANCE CREEK FRENCHMAN LAKE at FRENCHMAN $1 CREEK FRENCHMAN DAM LITTLE LAST CHANCE CREEK 1 eig? K5CHILCOON GENERAL LOCATION WESTER 0 RR. MILES . 31 A Figure 10. Location Map?Frenchman Dam and Lake CHAPTER II. FRENCHMAN DAM AND LAKE General I and Location Frenchman Dam is a 139-foot-high, homogeneous, ;arthfill structure with internal blanket and chimney Irains. The spillway is located on the right abutment. lOescription has an unlined approach channel; a 50-foot-wide, ingated, ogee crest; a 30-foot-wide rectangular chute; ind a flip-bucket terminal structure. The outlet works it s located along the base of the left abutment. Figure 11. Aerlol View Frenchman Lake has a capacity of .')5,477 acre-feet at spillway crest, a water surface area of 1,580 acres, and a 21-mile shoreline. Frenchman Dam and Lake are located entirely within the Plumas National Forest on Little Last Chance Creek, a tributary of the Middle Fork Feather River. The site is about 15 miles northeast of Portola and about 30 miles northwest of Reno, Nevada. The nearest major roads are State Highways 70 and 49 and U. S. 395 (Figures 10 and 11). — Frenchman Dam and Lake 13 . A statistical summary of Frenchman Dam and shown in Table 2, and shown on Figure 12. Lake the area-capacity curves are is Nevada on the southeast corner of the tilted Diamond Mountain fault block. Pre-Cretaceous granitic rock was covered by Tertiary volcanic and pyroclastic Subsequent erosion of the volcanic series of rocks carved deep canyons and, in places, completely uncovered the older granitic rocks. The Dam and reservoir are mainly on the volcanic series of rocks. Frenchman Dam is near a seismically active area along the California-Nevada border. rocks. Purpose The reation principal purposes of Frenchman Lake are rec- irrigation water supply. Flood control and is an incidental benefit but was not considered to be a purpose. Operation studies indicate that the reservoir is capable of supplying an average of 10,000 acre-feet annually for irrigation through controlled releases without an adverse effect on the lake storage for recreation. Chronology Investigations of water and recreation development Upper Feather River Basin resulted in published reports in 1955 and 1957 (see Bibliography). In in the Design Dam Description. The 139-foot-high embankment was designed as a homogeneous, rolled, earthfill structure with internal sloping and horizontal drains located downstream from the axis. Embankment general plan is shown on Figure 13, and sections are shown on 1957, the Legislature authorized construction of five in this development. One of these was French- Figure man Dam. mined by the Swedish dams Preliminary design work included economic comparisons of rockfill and homogeneous earthfill dam sections as well as economic comparison of four sites on Little Last Chance Creek. From this work, the type of dam and final location were chosen. Final design work was initiated in September 1959, 1959. and the Dam Construction began in was completed in 1961. reservoir are in the northern Sierra TABLE Slip Circle Cases analyzed included loading of full reservoir and lower reservoir levels along with earthquake loading. Earthquake loading involved a foundation critical horizontal acceleration of O.lg in the direction of mass being analyzed. 2. Statistical Summary Settlement. Since the Dam was to be founded on no foundation settlement was anticipated; therefore, settlement analyses were conducted on embankment material only. Tests indicated a maximum Dam and of Frenchman Lake SPILLWAY Type: Ungated ogee earthfill Crest elevation Crest width Crest length 5,607 feet 30 feet 720 crest with lined chute Structural height above foundation 139 feet 537,000 cubic yards Embankment volume 50 feet Maximum OUTLET WORKS 55,477 acre-feet 2,335 acre-feet 1,840 acre-feet Maximum operating surface elevation Minimum operating surface elevation pool surface elevation maximum operating elevation maximum operating elevation.. minimum operating elevation. Surface area, Surface area, Drainage area Average annual runoff 14 surface elevation feet pool storage Shoreline, 14,200 cubic feet per second 7,950 cubic feet per second 5,600.5 feet Peak routed outflow 19 feet 19 feet Maximum operating storage Minimum operating storage Dead surface elevation Standard project flood inflow FRENCHMAN LAKE Dead bucket 32,000 cubic feet per second 15,000 cubic feet per second 5,607 feet probable flood inflow Peak routed outflow Maximum Freeboard above spillway crest Freeboard, maximum operating surface Freeboard, maximum probable flood flip feet 5,478 feet 5,468 feet axis and 5,588 feet Crest elevation Crest length Maximum Streambed elevation at dam Lowest foundation elevation in- stability of the FRENCHMAN DAM Type: Homogeneous Dam was determethod of analysis. Stability of the rock, Regional Geology and Seismicity The Dam and 14. Stability Analysis. _ Type: Reinforced-concrete conduit beneath dam at base of left abutment, valve chamber at midpoint discharge into impact dissi- — pator 5,588 feet 5,520 feet 5,517 feet Diameter: Upstream of valve chamber, 36-inch concrete pressure conduit downstream, 30-inch steel conduit in a 6-foot - 6-inch concrete horseshoe conduit 21 miles 1,580 acres 171 acres Intake structure: Uncontrolled low-level tower with concrete plug emergency bulkhead 82 square miles 27,000 acre-feet — Control: Downstream control structure housing 24-inch fixed-cone 30-inch butterfly guard dispersion valve and 8-inch globe valve valve in valve chamber 165 cubic feet per second Capacity — AREA-ACRES ELEVATION-FEET 2600 2400 2200 2000 '300 I600 I400 I200 I000 300. 600 400 200 5600 556 50' \4/9 7 5540 5520 5500 5450 ACRE-FEET Figure 12. consolidation of 4% for 8 tons per square foot. Most of the settlement was expected to occur during con- struction. A nominal crest camber of 12 inches was provided. Construction Materials. An alluvial terrace 2 miles upstream of the Dam site was selected for bor- row on the basis of surface examination, auger holes, and testing of materials sampled. Natural moisture ranged from 12 to 51% and specif- ic gravity from 2.66 to 2.80. Shear tests showed an angle of internal friction of 30 degrees and a cohesion of 500 pounds per square foot (direct shear, con- solidated-quick; and triaxial shear, consolidated-un- drained, and consolidated-drained tests were run). Permeability range was determined to be 0.0007 to 0.0010 of a foot per day. Riprap and bedding were found at the Dam site, but filter and drain materials had to be imported. Foundation. At the Dam site three members, or layers, of the Tertiary volcanic series of rocks dip about 40 degrees southwest into the right abutment. One of these members, an olivine basalt flow, forms Area-Capacity Curves most of the left abutment down to the stream channel. Pyroclastic rocks, mainly an andesite tuff breccia, un? derlay the channel section and lower half of the right abutment. The pyroclastic rock in the channel was covered by alluvium which was removed during foun- dation excavation. Capping the right abutment is a layer of hornblende andesite. A normal fault, dipping 30 degrees to the southwest and striking nearly perpendicular to the dam axis, passes through the intake tower foundation and along the left side of the channel section. The fault zone, from 2 to 4 feet wide, contains brecciated to clayey sheared rock and seams of fat clay. Rock several feet on either side of this zone is strongly fractured and platy. The fault forms the contact between the tuff breccia and altered basalt in the channel section down- stream from the cutoff. A grout curtain approximately 50 feet in depth was placed across the entire length of the dam foundation. A second grout curtain approximately 100 feet deep was placed upstream of this curtain and was intended to grout any cavities not reached by the 50-foot cur- tam. 16 15-aam era! :1 ?are uer/ nab.- 11-;1 n'wu'w Au- am aloe 1 t: Figure 13. General Plan and Pro?le of Dam ?irt/9 I a r41?: .mve ?:32?er mm. [Imam Au 1mm mu pom- cum Hall; - Jim! I GENERAL sum mgr/:4? :u-num ?chum(wan-n fray? nan mi mun Amoc- lulu/w POI/non! ar um"; 59mg! mm" nun .r .35 gunner an" Ila?- ll 3 .a nwm- ..- . .. a 1 f-?za- 1:an- "mu-Ammu- man?um ruvu- am: ?on? rum? an" amino! FRENCNIAN DAI AND RESERVOIR DAM pun ARD "on? r4343! .. .- .. z-vav-J a" - - ?vv- . 7-7 .. . . ,,xm_1mm_ an nu 1.. snouoas Mammy?Va 0-: 4r?. Jquu/?mv 1r nous]: ?on cm are ?mania: mama nun urn-n nun .7. mum-unmanned .. 'Ii" ?r "ofnuns uaf F?a't?lvl'r- an war no ?1.77 JV Ala/1935? aways :4 ?aw . m; ?44414.mom ?put .. 1.00.110 wonpu- m? .. . rum: ?V-x 01404.nun u< "may? no.5 ~r-u I My r113? wanna"Mum?, - :7/7'130 NMM ?17: .. 4/1 . .- 4 ?an. sum[at-40w \x - 1-?le . . .. - . ?95:1: 4 "0'!an A a Ia ?mummy-u: 96' ?7 4- - - (?pH-ha: A V- (?4cstu A mum-amount: r. 4va-nj .7 mmam?mw ntm/uw? ,4 . ?94- r?mfmuf?mmWrd? .10 u. .. I ?sum?, .w r, . a . mu?: racy ?vol: - . 5 ??00 a purmtm ?wrvc y? A a? . .I flu?ul wak'uuam- (?-111 . h/ 4 .4..- 0991f!) IlDdf . ., .?llrxao?v/ICFDJ lam-404qu Maya .I, .. - manna . t? ,Or q.ull 10 Laws; A ~a .5. Mu)? .-. nu n, u?oqv x) 10m II.- 1 6-7 wn.t?.g am? ,2 . l7 Instrumentation. Instrumentation at Frenchman included (1) embankment settlement monuments, (2) piezometers, (3) electric pressure cells, (4) a cross-arm settlement unit, (5) observation wells, and (6) a seepage measurement weir (Figure 15). Dam Outlet Works Description. The outlet works is located along the base of the left abutment. It consists of ( 1 ) a low-level intake tower with a concrete bulkhead that can be lowered to seal the opening; (2) a 36-inch, reinforcedconcrete, pressure conduit from intake to valve chamber; (3) a valve chamber containing a 30-inch butterfly valve located just upstream of the dam axis; (4) a 30-inch, steel, outlet pipe installed in a 78-inch horseshoe conduit from the valve chamber to the downstream terminus; and (5) a control structure with discharge valves and stilling basin at the toe of Dam (Figure 16). Access to the valve chamber is A bulkheaded, 18inch, penstock wye was installed on the 30-inch outlet pipe 11 feet upstream from the control structure to provide for possible future power development. A gauging weir is located downstream from the stilling basin to provide measurement of flow through the outlet works. Because of the wide range of flows to be controlled, two discharge valves were installed: a 24-inch fixedcone dispersion valve to control high flows for irrigation (up to 88 cubic feet per second with reservoir at elevation 5,520 feet) and an 8-inch globe valve to control low flow for maintaining fish life in the stream (as low as 1 cubic foot per second). Rating curves are -shown on Figures 17 and 18. the through the horseshoe conduit. Structural Design. The intake structure is a tower approximately 34 feet high with outside dimensions of 5 feet by 5 feet and an inside diameter of 36 inches. It was designed as a vertical cantilever, fixed at the base. Loading cases included: (1) construction condition, no embankment in place, and a horizontal wind pressure of 15 pounds per square foot; and (2) at-rest earth pressure of the finished embankment and reservoir pressure. Trashracks were designed for a differential hydrostatic head of 40 feet. Yield point stresses were allowed in the trashbars while normal working stresses were allowed in the supporting concrete members. Upstream and downstream conduits are composed square inch in tension and 12,000 pounds per square inch in compression. Mechanical and Electrical stalled in February 1963. ventilating system operated by a '/^-horsepower motor with an output of 406 cubic feet per minute was installed in the control house to ventilate the valve chamber and conduit. Spillway Description. abutment. It The spillway is located on the right consists of an unlined approach channel; a 50-foot-long, ungated, ogee crest; a transition chute section; a 30-foot-wide rectangular chute; bucket terminal structure (Figure and a flip- Two bridges cross the spillway: one at the crest for connecting U.S. Forest Service roads, and one at the lower end to provide access to the control structure. 19). Hydraulics. Reservoir storage above the spillway reduces the standard project flood from a peak inflow of 14,250 cubic feet per second (cfs) to an outflow of 7,950 cfs with 6'/2 feet of freeboard and the maximum probable flood from a peak inflow of 32,000 cfs to an outflow of 15,000 cfs without any freeboard. Structural Design. Crest walls were constructed monolithically with the ogee crest and were designed for (1) normal earth loads plus live loads on the bridge, and (2) normal earth loads plus seismic loading. The crest is anchored with No. 10 reinforcing bars embedded 6 feet into the rock foundaton on ap- proximately 5 '/2-foot centers. The upstream end is provided with a 6-foot-deep cutoff and a 25-foot-deep grout curtain. The crest was designed for loads transferred from the walls and for uplift conditions during maximum spillage. Walls and floors of the transition and chute sections were constructed monolithically. Floors are anchored with No. 9 reinforcing bars embedded 6 feet into the rock on approximately 5-foot centers in both directions. The bucket was designed with a 50-foot-radius curve with a 20-degree upward deflection. floor upstream of the cutoff is anchored with ney drain. The 18 120- A vertical 30-inch outlet pipe was fabricated from '/-inch steel plate with a yield point of 30,000 pounds per square inch. It has a '/2-inch mortar lining. The pipe is set on saddles inside the horsehoe conduit and is designed with allowable stress of 16,000 pounds per A generating set is provided at the control structure to supply power for lighting and ventilating. All valves were intended to be operated manually; however, because of the time required to develop sufficient hydraulic pressure by hand to operate the 30-inch butterfly valve, a motordriven linkage powered by the generator set was in- of monoliths approximately 25 feet long with waterstops at each joint upstream of the embankment chim- The Installations. volt, 3, 000- watt, gasoline-operated, flip three rows of No. 9 bars embedded 6 feet into the rock 4foundation at 6-foot centers in both directions. inch pipe surrounded by filter material is provided beneath the concrete floor to drain the bucket founda- A ?1 c-vav?s. frF-a an ?r5355 ., I . '13: DIVE 5V wva . .a ONV NVO nousmo um nun: nun gyro-4 nun. n-nr 49~ -J Iva/13.75 5 0.. ?mm? [a . .md w- nun" ?4 4e nun u/Ma . *2 I~f?t 2: min?. (van/mace]; . ?mg a) V, ?h urgp .4 amt-Ia ?ou- m4 1 "ml-W ww 0 1.435 a?d my.? 4., . mmwwnun?) 10/ "my .- -. . orig/>10" (In-rim w; am? ru- a raft} . .V rmmy . "um/all: 10400 aw Io mm: mm pan/I40 - pm g. ., yummy,? ?Iuvol/I/rw g. mew-?mam lnrta)w g. Wham/M nun-Mum ?mum. mrn70/I no -, 5794119; p? ?6-5 00/ la.u?oo 11101111. 9 [Wu/4 ?mama.? r: )u/wn? a, inlouddo ?a 1 9/ 341. . 5 an? :1 14121] Ina/mu; r? mum", n. ,4 - again {Lil/11mm rim-luau? (gt. . m. madam: moo?; - my.? 9 9 you?: My, a Alualjll v-V val/2': a! ?40 ?mama 51.- aunt a, m, .Ju - "ammo away/wow 711.7; 1 5.74/3 ,u 1 a run-nu,? I [yondq?lr ?mummy or 4w awry-v.? ?w aw ?4 lww?wm x: was [Ina-~r7d 7vy2~39 10w?: 9441 and may0151' a 09-? 119/04: - ~40" 9 a: numruuw (ma/an I ?w?u A W, uvwll-u: .I- "upon, luau ,n ?vial/(0M um a: a a ?Imam rrm??. . ,5 human/[u mun, Alma?! ru?olw wow .3, . . 444244pan-u- ma(?MW/Inuw4/ .vtl?ll?laj? - A ?1 7W 1,-muJ wl/411ao m; 14-.th I ?5 [1:25 7/713? {hum ?1mm: . Amlww . ?oi/?WV ?jlm? ?1'?ij Li, In? pair 11% . ww?uml a7 77.7.7 Jansmad I-gw- -, (no: 1w w} mama-nu a) .wm: 9' pump 1(nan) Mu mix-.- . . hon-4 - 1 '4aom Hanna/1 aux/u? urnrud . MUM/rip adopt/agony?; "all ale 1111/ puma In: our". mayo/um mainly Imp-Q .407 Wow-v: 4, . ?1 - am: ??l'lf "mun M144 1 my: II . Sun-141100; 7 ?ung?; Loco?on of Embankment Figure l5. l9 20 Figure 16. Generol Plan and Pro?le of Outlet Works sc'won'- 419-7 v: ".14 m. oJ-u .mu 1 an], 1 I, mummy. 4 ?my. Plan Am? mm mm (to. sun ?uugl 39.: (may 7? m. m: Minn/1? nun-r uni-h: SM 701:? An: an: . [Pt 1" fawn-mu gum.? ?441?mun drum hlarlk!? :ua- chart lm' :mr. r- rn' .M?Auz 1pm- aw.- ,m r. ?1.414.441?; rags?: mm: uwa nw mum/r m; len ?4 34Ian51.x? "my n11 ..-.. . nu: ma. bran 5-5. 5? SirI/or/J- HQ 10:71; Hm 0? of WOHKS 3mm m- .. ?11" m! 71-1 a! an In?. 5m.- r-Ia' ?fhmw?un . um. - 5 710? 0-0? 5n? I-u Elm." f" :m .r ulhhu rid/I7 ny rmaqr mum? mun-1n?! mm? .1 undid p1?. war .1 m, IE AS BUILT (Luz Wu Inoxc! menus. on! mm,- An. mu In mun J'n: I we ma alarm" 0 m] 7?an Mm? .mm N'lwl . may 1751' gin/[PAL i ?In. Imam. Sf; 5" 'rar I . -.. ?l . [my 1'?plan I ham: ,4 lrf/Jn 1) Dan. full-Ly, hm Mm (MM owl-y Ann: land I apr<1194 a. fairy?gure: Iatr?yonOr?iaa" man ch aa,menl m? at mad! (an. 311??! work: a 0' awe a a: mavf a! Pg!? rI far [max r- -u?l A. Mad: rar Wu? .. Sir-fa: 'q a? 'u Amuc?mm no I-as ?mm A. urn-v 5mm? ?mg-?ta Mm; nun-a..? nomaumm mun?um- mm- - "mu! VEAYNE IIVEI DIVISION FRENCNMAN om AND OUTLET WORKS BINEIAL PLANS AND SICYIONS .m um gu- JP wry . Siff/DA/ F-F 51w. F;4as-I 5590 CREST OF SPILLWAY ELEV. 5588 5580 UJ UJ 5570 > UJ -J LxJ 5560 UJ O < U. a: 5550 CO tr UJ <5540 O > oc 5530 Ul (O UJ or 5520 Lip of Outlet Elev. 5517^ Tower 5510 40 80 120 160 DISCHARGE -CFS Figure 17. Outlet Works Rating Curve (24-lnch Hollow-Cone Valve) 21 (FEET) RESERVOIR WATER SURFACE ELEV. 5590 I 4 7? CREST 0F ELEV. 5588 4" 5580? 5570 5560 I to v. ?9 5550 f? 5540 5550 5520 d: I Lip of Outlet Tower Elev. 55/7 55' 1 I 01234567'89l0ll DISCHARGE-CFS Figure 18. Outlet Works Rating Curve (8-lnch Globe Valve) 5 87401 23 In? '4 mun?m 4; Iv ?-31:11 am rm -. 3-5, :11? gay!" 4 Q, burial/Fund . A - -. "It-5? ?q'mu?m - A 1 I: I'll! Iranmay.? a. m, ?ier! an.? fa; (?can Jar!? a: 35mm o-o . . angel?; . - . Inwa'u "ah 4 4 eavio?l [an Fanlw . - 2 .wdnh Figure 19. as w; 4m .4 Dan. I .1 mm Mum? mom: 4mm; ?vamn?m?udrama-0w 3/ '3 if": f?ux . Munro/Iv" .- me up.) (mu! ovum-M .4.th cum: an a Jmu/ amp-ma .mpumu Iw W) m: an wan?Lu".l noon-rm: . -o u' an u-uvuHAS "runnerBUILT FRENCHMAN DAM lparn/I, ?no - n4 up?: (11/ General Plan and Pro?le of Spillway PLAN IND IIESEIIVOII SPILLWAY AND SECNONS n' I ?(Jr al .. ., In! gang l. 4- -. -.-, V?w- storm/v 6?6 i In 7:413,? 2% any! .. :mm?qLe-oLz?r .52; -L ..-- F-aesLI To Construction General information for the construction contract Frenchman Dam is shown in Table 3. The princi- for pal features included in the contract, designated as Specification No. 59-19, were an earthfill dam, spill- way, outlet works, and relocation of portions of U. 3. Major Contract occurred, the most effective treatment was intermittent low-pressure pumping of thick grout. The grout then was permitted to harden in the hole, which was redrilled and regrouted in the succeeding stage. Uplift due to grouting was negligible (maximum recorded 59-19 21,809,110 21,708,093 222,485 9/15/59 Isbell 10/18/61 Construction was Com- pany Diversion and Care of Stream Diversion of Little Last Chance Creek during construction was the responsibility of the contractor. The outlet works was utilized. Between the time the foundation excavation was begun and the outlet works completed, streamflow was pumped around the job site through a 6-inch aluminum pipe extended along the left abutment. A cofferdam upstream of the toe of the Dam was placed and the impounded water transported to the outlet works at the base of the intake tower by a 36inch reinforced-concrete pipe. This pipe was left in place and plugged with concrete at its junction with the base of the intake structure after its use for diversion was discontinued. Downstream water requirements during the remainder of the construction period were fulfilled by means of a 6-inch bypass between the diversion pipe upstream of the concrete plug and the outlet conduit. Foundation Dewatering. A 1 5-foot-wide cutoff trench was excavated to bedrock between the cofferdam and the upstream toe of the Dam. A 24-inch, perforated, corrugated-metal pipe with a 12-inch riser was installed and the trench was backfilled with drain rock. Water accumulating in the pipe was removed by pumping from the riser. A Excavation. total of 50,953 cubic yards of unsuitable foundation material was removed from the streambed and abutments. Cavities in the right abutment were filled with concrete. The largest was mined to a depth of nearly 50 feet. It contained a preserved and approxiestimated to be 10 million years old. Portions of this trunk were preserved for display. An auxiliary grout curtain 100 feet in depth was placed around the upstream limits of the cavity area. tree trunk, V/^ feet in diameter 24 feet long, material. A total of 6,567 cubic feet of grout was injected into the foundation. Where surface leakage — Frenchman Dam Total cost-change orders Starting date Completion date Prime contractor mately 20 embankment Grouting. Specification Low bid amount Final contract cost redwood in the S. Forest Service roads. TABLE reduce the possibility of seepage through a fault stream channel, all sheared and strongly fractured rock was removed to a depth of several feet below the cutoff surface. A 5-foot-deep trench that varied from 10 to 20 feet in width was excavated along the fault in the cutoff area and then backfilled with zone Contract Administration '/^ inch). Handling of Borrow Materials Impervious. Impervious borrow material was obtained from lenticular to thickly bedded terrace deposits 2 miles upstream from the Dam site (Figure 20). Mixing of these deposits was accomplished by powershovel excavation from a vertical face approximately 30 feet high. In-place samples indicated that field 1 to 5% above optimum. It was, therefore, necessary to blend freshly excavated material with that which had been spread and dried. A total moisture was from of 515,632 cubic yards of excavation yielded 487,330 cubic yards of compacted impervious fill. Drain. Due to the fact that the contractor was una- ble to find suitable sand in the area for the drain, he imported 11,000 cubic yards of sand from Reno, Nevada (30 miles) and blended it with 5,000 cubic yards of local crushed andesite. Slope Protection. Approximately 22,000 cubic yards of riprap (1 cubic yard maximum size) was obtained from the andesite quarry located on the right abutment downstream from the Dam. Between 10,000 and 15,000 cubic yards of smaller rock for crushing into rock spalls and riprap bedding also was obtained from this source. Embankment Construction Impervious. The impervious fill was placed in designated lanes parallel to the axis of the Dam by six bottom-dump trucks and two scrapers. It then was spread into 6-inch lifts by bulldozers and mixed by disking. Compaction was accomplished by six passes of two double-drum sheepsfoot rollers in tandem, pulled by a tractor. Areas inaccessible to or missed by the larger unit were compacted by 12 passes of a single sheepsfoot roller pulled by a tractor. Special compaction near abutments and structures was accomplished by gasoline engine-operated hand compactors. Where this equipment was used, it was necessary to scarify and wet the top of each lift before placing the next one to avoid laminations. Design recommendations for embankment compac- 25 Figure 20. location of Barrow Areas and Frenchman Dam Site IMPER BOR ow VIOU a :y . -. 335,? 'In- 3 A3 BUILT .h_r .. tin DAM DAM SITE AND BORROW AREA LOCATION no." . a. Ax?; ran? AND RESERVOIR F-48l-3 ; tion were: (1) rejection of material with a maximum dry density of less than 104 pounds per cubic foot, (2) a desirable relative compaction of 98%, and (3) rejection of material below 95% relative compaction. Average dry density for all rolled fill tested was 107.0 pounds per cubic foot (pcf) ranging from 90.7 to 115.2 pcf, with an average relative compaction of 97.7% ranging from 91.4 to 103.8%. Average dry density for specially compacted fill (hand-held compactors) was 107.8 pcf, ranging from 100.9 to 117.2 pcf, with an average relative compaction of 98.8% ranging from 94.5 to 102.9%. Only borrow materials with maximum dry density exceeding 104 pcf were drawn from the borrow areas. Areas within the borrow where light materials were known to exist in substantial quantiwere avoided. Fill with a relative compaction of less than 95% was either rejected or reworked and ties retested. The embankment under construction is shown on Figure 2 and the completed Dam on Figure 1 22. Drain. The horizontal portion of the drain was compacted by four passes of a tractor, while the sloping portion was compacted with two passes of a vibratory roller. The decision to change methods of compaction was made after tests showed that the vibratory roller method of compaction resulted in higher and more uniform compaction than the specified method. To ensure satisfactory compaction upstream of the drain, the impervious material was lapped 1 to 2 feet over the drain during compaction, then trimmed back to a neat line. Slope Protection. Bedding was end-dumped onto the upstream dam slope which had been trimmed to firm material. Riprap then was end-dumped onto the bedding and selectively placed by a clamshell bucket and hand labor. Rock spalls were end-dumped on the downstream face of the Dam, shaped, then compacted by backing a vibratory roller over the slope with a tractor. Outlet Works Rough excavation was done with w^mm a ripper-equipped and a 2 '/^-cubic-yard shovel. Light to moderate blasting was necessary in areas of basalt. The fault zone parallel to the stream through the Dam site was encountered for about the first 100 feet upstream of the outlet structure. Loose material was excavated to a depth of 3 to 13 feet below grade and backfilled to tractor foundation grade with concrete. Where pyroclastics were encountered, initial excavation was made to within 0.3 to 0.5 feet above final grade elevation, and final grading was done the day before concrete was placed. This prevented rapid deterioration of the foundation surface and eliminated the need for spraying with protective asphalt covering. All areas of overexcavation were backfilled to foundation grade with concrete. Inasmuch as this concrete was placed during the summer, there was no need for cold-weather protection. Placement generally was routine and was accomplished with a truck crane and a bottom-dump bucket (Figure 23). Spillway Figure 21. 26 Embankment Construction Excavation. A total of 34,016 cubic yards was excavated for the spillway. Blasting was required only in the approach channel at the crest and at the upper part ! degrees Fahrenheit for the first three days after placement and above 32 degrees Fahrenheit for the next three days. To accomplish this, a plastic tent was placed over the walls of the spillway chute and steam was piped in from a steam generator for six days. The tent then was removed and a curing compound applied. The high by walls of the spillway crest were protected 2'/2-inch-thick batting surface. Single layers Figure 23. Outlet with an aluminum reflective were placed between the vertical Works Concrete Placement of the chute. Overexcavation was required at and below the crest where blocks of andesite were loosened by the blasting or taken from the foundation during ripping operations. Before the spillway slab was placed, cavities and areas that had been overexcavated were backfilled with concrete to foundation grade. Because the pyroclastic and sedimentary rocks in the foundation of the spillway deteriorated rapidly when dried or rewetted, it was necessary to spray them with a protective coat of asphalt to prevent slaking. T I ; ' ; i I Anchorage. Anchor bars were replaced by shear keys for about 100 feet in the middle of the chute when it became apparent that the foundation rock in this area would not provide sufficient anchorage for the ' ' I ' bars. i ' I ' I j '• I j " I I ' I I Concrete Placement. The floor of the spillway was placed by means of a steel slip form that was drawn uphill with a winch to strike off the concrete. Forms for the crest and wall were constructed of plywood backed by studs and walers. Placement of the spillway concrete was started in the fall of 1960 and completed in the spring of 1961. The sequence of construction was the floor slab first, then the crest, flip bucket, outlet works bridge and, finally, the walls and crest bridge. A total of 1,678 cubic yards of concrete was placed in the spillway and 83 cubic yards in the bridges crossing the spillway (Figures 24 and 25). . I Concrete Curing. If mean daily temperatures fell below 40 degrees Fahrenheit, the contractor was required to maintain concrete temperatures above SO Figure 25. Spillway Flip Bucket 27 studs and a double layer over the open concrete at the top. Six days later, the forms were stripped and a curing compound applied. Portable heaters were placed under the deck of the crest bridge to supplement the steam in the plastic tent, and blowers were used to circulate the air. The contractor suspended operations after December 6, 1960, and unstripped forms were left in place until the following spring. Uncompacted backfill behind the spillwalls was obtained from waste material rejected during the processing of other rock. Backfill. way Concrete Production Concrete was produced at a semiautomatic batching plant located about one-half mile upstream from the Dam. Coarse aggregate was obtained from a pit near Reno and sand from Washoe Lake, approximately 17 miles south of Reno. Mixing water was obtained directly from Little Last Chance Creek but, when the stream became dirty from eroded materials, it was necessary to truck water in from a different location. Concrete was mixed in 7-cubic-yard truck mixers for a minimum of 80 revolutions at the rate of 8 to 10 revolutions per minute. The normal load did not exceed 6 cubic yards. An air-entraining agent was used in the concrete to provide resistance to deterioration from freezing and thawing cycles which occur in the project area. 28 H Reservoir Clearing The reservoir area below elevation 5,588 feet was cleared of sagebrush, trees, down timber, rubbish, and farm buildings. Trees were cut off 1 foot above the ground. Fencing in the reservoir area was left in place as long as practical to fulfill existing grazing requirements and was later removed by department person- , nel. Closure Storage in Frenchman Lake was begun in 1961 by closing the 6-inch bypass valve on the inlet tower. Early in March 1962, it became apparent that the reservoir level would not be high enough by the start of the irrigation season (March 15) to release waterright entitlements (up to 94.4 cubic feet per second) through the outlet works. The need to pump water to meet downstream requirements during the closure was eliminated by executing individual agreements with downstream water-right holders. The maximum storage in 1962 was 13,811 acre-feet; therefore, only fish and stream maintenance and water entitlement releases were made in that year. In February 1963, the reservoir rose above the mini- mum recreation pool of 21,425 acre-feet. It exceeded 43,000 acre-feet in May 1963 and dropped to a low of 31,383 acre-feet in October 1964. The first spill was in April 1965, and the reservoir has spilled in about half of the succeeding years. It has remained above a pool of 36,000 acre-feet since October 1964. ' ; j l -i BIBLIOGRAPHY California Department of Water Resources, "A Plan for the Development and Operation of Recreation Facilities at Frenchman Reservoir, Upper Feather River Basin", March 1961. Bulletin No. 59, "Investigation of Upper Feather River Basin Development: Interim Report on Engineering, Economic and Financial Feasibility of Initial Units", February 1957. , , Bulletin No. 59-2, "Investigation of Upper Feather River Basin Development", October 1960. "Design Report for Frenchman Dam", December 1966. California Department of Public Works, "Northeastern Counties Investigation: Report on Upper Feather River Service Area", April 1955. "Program for Financing and Constructing the Feather River Project as the Initial Unit of the California Water Plan", February 1955. Diller, J. S., "Geology of the Taylorsville Region", U. S. Geologic Survey Bulletin 353, 1908. . , 29 GENERAL LOCATION 0 BUNTINGVILLE 0 2: ?139 L. 2? NTE PEEK . A LOP DAM may" 0 2 Q: 32' ?5:1 0) 0 MILES 3 GENESSE I Figure 26. Location Mar-Antelope Dam and lake CHAPTER III. ANTELOPE DAM AND LAKE Description and Location Dam consists of two zoned earth embank120-foot-high main dam and a 60-foot-high Antelope ments: a auxiliary dam. The spillway is located on a ridge between the embankments. It is an open channel struc- ture with a 60-foot-long ungated weir. An outlet works, consisting of a low-level intake tower, a 36-inch steel-lined pressure conduit, and is located along the base of the right abutment of the main dam. Antelope Lake has a capacity of 2 2,.'566 acre-feet, a water surface area of 931 acres, and a 15-mile shore- ture, General a control valve struc- Figure 27. Aerial View line. Antelope Dam and Lake are located entirely within the Plumas National Forest on Upper Indian Creek, a tributary of the North Fork Feather River, 43 miles by road northeast of Quincy. The nearest major roads are State Highways 70 and 89 (Figures 26 and 27). —Antelope Dam and Lake 31 A statistical summary shown in Table 4, and shown on Figure 28. of Antelope Dam and Lake is the area-capacity curves are Regional Geology and Seismicity Antelope Dam is near the northern extremity of the Nevadas on the westward-tilted Diamond Sierra Mountain Purpose fault block. The site is in a relatively small by Tertiary and older volcanic and metavolcanic rocks. Pliocene and Pleistocene volcanic rocks of the southern Cascade Range and Modoc Plateau lie as close as 20 miles north of the granitic area surrounded The purposes of Antelope Lake are streamflow maintenance and recreation. Flood control is an incidental benefit. Operation studies indicate that the reservoir is capable of releasing 20 cubic feet per second from April I through June 30 and 10 cubic feet per second during the remainder of the year without an adverse effect on the recreation water level of the Lake. These flow quantities were determined with the guidance of the Department of Fish and Game to be sufficient to provide fishery enhancement in the stream below the Dam. They also will meet downstream water rights. Surface drawdown will vary from 2 to 12 feet, averaging less than 6 feet. Volcanically active Mount Lassen lies approximately 50 miles to the northwest. Honey Lake Valley, which consists chiefly of Quaternary Lake deposits and other alluvium, is about 10 miles to the northeast and belongs to the Basin and Range provinces. Relasite. tively small deposits of Tertiary auriferous gravels, deposited by the ancient Jura River, occur within the Indian Creek drainage basin and partially have been reworked to form a portion of the Quaternary alluvium and terrace deposits found adjacent to the Dam Chronology site. Investigations of water and recreation development in the Upper Feather River Basin resulted in published reports in 1955 and 1957 (see Bibliography). In 1957, the Legislature authorized construction of five dams in this development. One of these was Antelope Studies of seimicity from 1769 to 1960 indicated the site is in a seismically active area. Most of the earthquakes affecting the site originated in Genessee Valley, Honey Lake Valley, and Mount Lassen National Park. Maximum intensity experienced at the site probably was 7 on the Modified Mercalli scale. Dam. Preliminary design involved studies of three embankment axes, and the final alignment selected was based on minimum embankment quantity. Final design work was initiated in 1961. Construction began in August 1962, and the Dam was completed in 1964. TABLE 4. Statistical Summary Dam Design Dam Description. Both the 1 20-foot-high main dam and the 60-foot-high auxiliary dam were designed as zoned Dam and of Antelope Lake ANTELOPE DAM Type: Zoned SPILLWAY Type: Ungated ogee earthfiU 5,025 feet Crest elevation. Crest width Crest length 30 feet crest with lined chute Streambed elevation at dam Lowest foundation elevation axis- Structural height above foundation. Embankment volume 60 4,918 feet 4,905 feet 120 feet 380,000 cubic yards probable flood inflow Peak routed outflow Maximum operating surface. probable flood surface elevation Standard project flood inflow Peak routed outflow Maximum Freeboard above spillway crest maximum maximum bucket feet surface elevation Maximum operating storage. Minimum operating storage. pool storage 32,500 cubic feet per second 23,400 cubic feet per second 5,025 feet 18,300 cubic feet per second 12,900 cubic feet per second 5,017 feet 23 feet 23 feet Ofeet OUTLET WORKS ANTELOPE LAKE Dead flip 1,320 feet Maximum Freeboard, Freeboard, and 5,002 feet Crest elevation. Crest length 22,566 acre-feet 500 acre-feet 500 acre-feet Steel-lined reinforced-concrete conduit beneath discharge into impact dissipator of right abutment Type: — dam at base Diameter: 36 inches Maximum operating surface elevation. Minimum operating surface elevation.. Dead pool surface elevation 5,002 feet 4,950 feet 4,950 feet Intake structure: Uncontrolled low-level tower Control: Shoreline, maximum operating elevation Surface area, maximum operating elevation. Surface area, minimum operating elevation. Drainage area Average annual runoff. 15 miles 931 acres 57 acres Downstream butterfly valves Capacity control structure housing 10- and 24-inch slide gate on intake tower 136 cubic feet per second —guard valve, 36-inch 71 square miles 20,900 acre-feet 32 ^lT AREA IN IOO ACRES NORMAL WATER mo_ SURFACE EL. 5002.0' 506?, h? r? ?9 STREAEE ?CAPACITY IN I000 ACRE FEET Figure 28. earthfill structures consisting of upstream impervious zones of decomposed granite and pervi- ous zones of Streambed sands and gravels. The em- bankment plan is shown on Figure 29, and the sections are shown on Figure 30. No instrumentation of the embankment was planned during design. Stability Analysis. Embankment slope stability was analyzed by the Swedish Slip Circle method. Sat- isfactory safety factors were established under all an- ticipated loading cases. These cases included full reservoir and other critical reservoir levels along with earthquake loads. Earthquake loading was assumed to be an acceleration of the foundation (0.1g) in the di- rection of instability of the mass being analyzed. De- sign strength for the impervious material was determined by soil testing while that for the gravels was based on published information for similar material. Settlement. No rigorous settlement analysis was made. Consolidation tests indicated that practically all settlement would occur during construction. A cam- ber of 1% of the fill height was provided. Construction Materials. On the basis of surface examination, boring logs, and soil test data, decom- posed granite at a site in Antelope Creek about two- thirds ofa mile upstream of the Dam was selected for impervious borrow. In-place moisture ranged from 4.4 to 13.8%, averaging Specific gravity values ranged from 2.67 to 2.80, averaging 2.74. ln-place dry densities ranged from 92.2 pounds per cubic foot (pcf) to 100.8 pcf. A maximum dry density of 122.6 at an optimum moisture content of 11.5% was obtained Area-Capacity Curves from material that had a field value of 100.8 in- dicating a shrinkage factor of approximately 18%. Di- rect shear tests on impervious fill showed a strength of 33 degrees for effective stress analyses, and a strength of 31 degrees and cohesion of 200 pounds per square foot for total stress analyses. Permeability of the compacted material ranged from 0.0002 to 0.09 of a foot per day, averaging about 0.01 of a foot per day. Streambed sands and gravels from within the reser- voir area were selected for the pervious embankment. Areas of free-draining material were delineated based on exploration with backhoe trenches. Sampling was accomplished in the trenches. Average compacted dry density was found to be 137 pcf. Permeability for com- pacted samples in this density range was from 1 to 7 feet per day. Testing showed that permeability de- creased rapidly as density increased to 140 pcf. Strength of the material, based on testing of similar materials, was assumed to be 38 degrees. Foundation. Rock occurring at the Dam site is biotite granodiorite, which has a shallow cover of allu- vium along the stream channel. The channel section consisted of jointed fresh rock overlain by varying depths of silty sandy alluvium which was removed during construction. Outcrops of vertical and overhanging rock were shaped to a l/2:1 maximum slope against which the embankment material could be compacted. A cutoff trench of varia- ble width and a single grout curtain consisting of two 25-foot grouted zones (total depth 50 feet) were pro- vided for the main dam. 33 34 Figure 29. General Plan and Pro?le of Darn Ewan], - - rm angmal grow-.1 zma? a :06? Fe "era/ . par/m area aarcrac 1.2.14 9 Mi ~y4raw can/r4: may[159: a ban knell caravaf-a? :ha'l I f\ I?Mcuwwmg 0' .- (opalr Ibbts (3, or am. n9 arru an r: a: . 4 '1 cam? .ar .5 u?I- foam, 0 barn-Ia mmr; mum 31 I) kn. I Ann?a- an 31"?ll yarr Jaye! Cara/r she? errand no dam any on all acurmc-vrs -L-"7hfs :r Jam . foundanon - fc? DIF?atamd wan a, 50:0 - Draw-age ch (ch PM r. 0?11!? .nnu ?trough pm) on flu-w no u. r- y. u: u/rmAccau road raauhe' .var?s .anr?al srrucIur-e CA Jove War 'a 1::10 Gar-rs arts! 61 50250 W-fhouf can-mor- graund mu :aoa Eyhmarpd ?burly; (BIO 1.3'55 ?iv-we: m, rum . 1v- many ?9 >07 fu'?vsh'?g .n 9mg.? .1 I may:uf?3:r mam: din two (gnu . 19> -m?r eras as usuuvr 4320 y" ALONG OF 0AM 55.: MC A- A a, ?macaw/1r.? "coma?m 3' o' 5m.? 5 5 ?afar 23;: 4 "ram?anm a, Parry: and Asloalafls 5::an 'vvo-o' our?: m? Safews :or-aur mmwar :3 art?cal 30mm, . Au-Fba- La'es S?o'a ?'Da'ana'a 5,5ram ?am! I ugav? gr snl?v?wa) no; War/1 CAMEEP 0/11 GPA baffam 7999 FoJua?aU no?- a 495 la a 4.950 val lb scale 3 Sgt/hwy, El. 43:: I: 5.. 5w Delfrrarr Argo Hop .shear J) 9.79:: r: 'ace dam 00" Sm ?ar-?Jw baa zocawan 5'251?? 1 5510' 5040 cam era? EL 50:60 mmout camaar 5'"le 59:! :35] 251500.! 5., I :r - I ELEVA r/cw 57A FF GAGE 750757937 3 We 9? 5000 Eslrmafao eocarahan 9900 AS BUILI 5? 0' "Am gc?? mi our 554 ?l uvlu rump: 0 AS BUILT ANYELOPE VALLEV mu AND RESERVOII '0 Scavl ?ar?aur cur-ram Sea ?on. {5 I 4. DAM PLAN AND PROFILE 4am Wm 49:0 ?90 0N6 41/5 0F MA IN 014! LOOKING (/957054/4! 560M .mm. .m N. I . mum-Ln bin-Fm- uo "Alf?:3 ?284-l sent or 35 law-mm mph-:1 ,c glluiy .own. a. a: mum: .-. - on c; .134 r- 35 ,Jl: u- ru34; 5&5 \l ?51! Orin ooxio Bum liar: l\l/ .14.. 9000.: Em .2 . . 54:82! Ilka? ally-II. I: . 9? \q nubhun = 34 degrees, C = due to shearing. Case 2 asthe "total stress" core shear strength of <^ = 14 degrees, C = 0.3 tons per square foot, which included the effects of full pore pressures due to shearing. Case effects of pore pressures sumed 75 Figure 64. Stability Analysis Summary nun-n mm mu. WI 4.5., .. nu -- That!? num- ILIKI nu nu uuvnu un numu an 3.3.1? 9? ?om :mm-w-n-umm-a v?u Inn". EXHIBIT le'b magnum-warn! munc- law rm- nnov o! anon?445-2 mun-w.? mm a! mu MI mu uaunn onovnu Immo- OROVILLE DAM DATA mm- punt-nun .u 3 assumed the strength of <^ unrealistically conservative core shear 0, or, in effect, a "fluid" core. 0, = C= was analyzed matter of interest and does not have any real status by comparison with the more realistic analyses of Cases 1 and 2. This latter condition, a "limiting case", only as a In addition to these analyses, two additional condi- what actually happens in an embankment during an earthquake; therefore, it was decided to make further earthquake studies for Oroville Dam. In 1961 and 1962, a series of model tests was conducted for the Department by the Engineering their approach as to Materials Laboratory of the University of California at Berkeley (see Bibliography) under the supervision of Professor H. B. Seed (Figure 65) These tests were conducted on a 1:400 scale model of the embankment, using horizontal earthquake accelerations up to 0.5g. They yielded some informative qualitative results but left some points unresolved due to the difficulty of scaling the influence of pore-water pressures during dynamic loading. If the prototype dam was subjected to a dynamic force which tended to cause movement along some potential shear surface, the deformation would be accomplished by either dilation or consolidation of the Zone 3 shell material, depending upon the load at any given location in Zone 3. The resulting dilation or consolidation would cause internal pore pressure changes which could not be included in a model study program but which could significantly . were analyzed by Moran, Proctor, Mueser and Rutledge Consulting Engineers. These additional conditions were (1) end of construction, and (2) rapid drawdown from elevation 900 feet to elevation 590 feet. Although the material properties used in these analyses differed slightly from the final values used by the Department, the results of this work demonstrated that the conditions studied were not critical to embankment stability and they were not pursued. tions While Oroville Dam is located in a region of low historical seismic activity in California, design to resist earthquakes was a major consideration in develop- ment of methods the final embankment section. Analytical available in the early 1960s for earthquake- resistant design of earth embankments were, at best, only an approximation and somewhat empirical in Figure 65. affect embankment stability. However, since known from previous laboratory testing what it was range of Embankment Model on Shaking Table 76 i ) loading caused the Zone 3 material to change from dilation to consolidation during shear, it was conclud- ed that additional analytical work could help resolve the uncertainties remaining from the model study program. One additional series of analytical studies upstream slope of the Dam. For this undrained strength of Zone 3-type materials was utilized in conjunction with results of pulsating load test performed on sands at the Univer- was made for the analysis, the Seismic coefficients of up to 0.25g were used. Also, the stability of the upstream slope of the Dam was analyzed for a design earthquake equal to the 1940 El Centro earthquake (peak acceleration 0.2Sg). Seismograph records of this earthquake were sity of California. the best strong-motion records available at the time and were considered representative of the most severe ground motions which could be anticipated at the site. The results of these studies supported the conclu- work dam embankment was sions of earlier that the designed conservatively with respect to earthquake loading in the light of currently accepted engineering practice. Other Earthquake Considerations. It is interesting to note that inherent in the conventional embankearththese additional were design ment quake-resistant features: 1. Dam embankment is founded directly on bedrock or, in the case of the outer shells, on a minor amount of sand and gravel with a density greater than that of the embankment, thus eliminating any possibility of foundation liquefaction. 2. The embankment zoning scheme provides a wide crest and wide transition zones of well-graded sand and gravel between shells and core. The transition is dense and relatively impervious. 3. The 22 feet of freeboard above normal maximum water level required for maximum floods is more than would normally be required for any possible combination of earthquake-caused reservoir waves and crest slumping. 4. ant, Core material is a dense, plastic, erosion-resist- extremely impervious material with a wide range of particle sizes. All material was placed at contacts with bedrock of concrete structures at an initial water content from 1 to 3% above optimum to ensure that a plastic zone is in contact with these more rigid elements. The sloping core was placed at or slightly wet of optimum to provide additional protection against potential cracking. Settlement, Pore-Pressure, and Crest-Camber Settlement, pore-pressure, and crest-camber studies were performed for Oroville Dam to ( 1 determine if pore pressures developed during construction would be detrimental to embankment stability, (2) estimate how much of the overall settlement would occur during and after construction, and (3) determine what effects postconstruction settlement would have on the dam crest so that compensating Studies. design provisions could be made for crest camber. Several gradations and moisture contents of Zone 1 material were tested and used in the analyses to provide a range of possible results. These studies indicated that construction pore pressures which could develop would not be significantly detrimental to embankment stability. They would not = 0, C = Zone I condition, so no further construction stability studies were deemed necessary. Settlement was studied at two important locations within the embankment: one at the maximum height of Zone 1 material, which was on a vertical line 242.5 feet upstream from the dam axis, and one at the dam crest, on a vertical line 10 feet upstream from the dam axis. These studies showed that regardless of grading, not over 2.5 feet of postconstruction dam crest settlement (due to simple consolidation) should be anticipated at the maximum dam section. The third objective was to design crest camber to compensate for postconstruction settlement using the above results of the previously mentioned studies. Some additional factors are summarized as follows: approach the Postconstruction consolidation of Zone 1 due to embankment load Additional settlement of Zone 1 due to water load Additional settlement of Zone 0.6 feet 0.3 feet 2 and Zone 3 due to full load Vertical deformation due to embankment shear strain Safety factor Total design camber at 0.9 feet 1.8 feet 1.4 feet maximum section The 1 5.0 feet actual settlement after seven years foot but is still continuing at a slow is less than rate. Foundation Oroville Dam is founded on an unrock formation, one of several units within the "Bedrock Series". The rock is predominantly amphibolite, a basic rock rich in amphibole with abundant veins of calcite, quartz, epidote, asbestos, and pyrite. It is hard, dense, greenish gray to black, fine to coarse grained, and generally massive, although foliated or schistose structures are not uncommon. Average attitude of regional foliation strikes 12 degrees west of north and dips 77 degrees east. Rock at the site is moderately to strongly jointed and is transected by steeply dipping shears and schistose zones. Three prominent joint sets impart a blocliness to the rock, but individual joints are relatively tight. The depth of weathering was found to be substantial and varied greatly from place to place. Site Geology. named metavolcanic Two major shear areas exist beneath the Dam, which are about mid-height on each abutment. Both are steeply dipping and strike normal to the axis of the Dam. 77 Fresh rock was exposed on the bank of the river channel and in minor outcrops on the abutments. Weathering of rock approached 100 feet in depth in the sheared zones. Subsurface geologic exploration was by the U. S. Army Corps of Engineers in 1944 with the drilling of two core holes, one on each abutment. In 1947, the U. S. Bureau of Reclamation drilled six core holes at the site. Explorations by the Department of Water Resources were begun in 1952 and those required for design were completed in 1959. Exploration. initiated They included the following: — Exploratory Adits Four 5-foot by 7-foot adits were driven, two on each abutment, together with 1. and cross cuts, totaling 5,251 linear feet. Core Borings 175 borings were drilled varying size from EX to NX, and in depth up to 200 feet, drifts — 2. in totaling 18,600 linear feet. — Surveys Supplementing a "depth of 3. Seismic weathering" survey by the U.S. Bureau of Reclamation in 1950 was a 1957 program consisting of 4,350 modulus of elastici- linear feet of spreads to determine ty and depth of weathering. — Special Studies Detailed evaluation of bedrock properties was made by carrying out the following 4. special investigations: Grouting. b. X-ray diffraction and solubility tests on clay gouge in shear planes Compression tests on rock cores c. Studies of blasting effects in the diversion tun- a. nels d. e. f. Test grouting mapping Measurement of ground water Rock-joint attitude levels and spring flows g. Bedrock-stripping methods, eliminating rip- modulus tests Additional information was gained from exploration for the underground powerplant and other strucIn situ rock tures. Excavation Criteria. The excavation criteria for the various parts of the foundation were: Concrete Core Block Sound hard rock consisting of fresh to slightly weathered rock, with unstained to slightly iron-stained fractures. Embankment Core Trench Sound hard rock that would be impervious after grouting. Trench slopes 1:1 or flatter downstream and Yi-.l upstream. Seams and shear zones excavated to a depth approximately equal to their width. Irregular rock to be removed to permit compaction of the core. — — — Embankment Shells and Transitions Weathered rock exhibiting definable rock structure of a strength equal to that of embankment materials placed thereon. A maximum single cement grout curtain of 200depth was provided in the foundation beneath the core (Figure 66). Forty-foot-deep foundation drain holes with a maximum spacing of 80 feet were specified to angle downstream from the grout curtain discharging into the grout gallery. Slush and shallow blanket grouting were provided to fill surface voids or to improve the strength of fractured areas of the core trench foundation. Core Block The ping and blasting h. foot 283,000-cubic-yard, lean-concrete, core block is monoliths (Figure 67). The primary structure has a flat top at elevation 250 feet. An upstream parapet rises to elevation 300 feet. Maximum height to the top of the parapet is about 120 feet. The base thickness at maximum section is about 400 feet and the crest length of the parapet is 900 feet. The purposes of the core block were to ( 1 ) eliminate the need to compact impervious core material in composed of 18 the irregularly eroded inner gorge of the Feather Rivreduce possibility of transverse embankment settlement cracks, (3) reduce maximum height of the core, and (4) expedite embankment construction. The core block with a 50-foot-high parapet served as a potential overflow structure. This allowed the expedited er, (2) placement of about 2,000,000 cubic yards of embankment in the upstream half of the stream channel in advance of the critical 1964 embankment construction season, in which the 400-foot-high cofferdam would be incorporated into the Dam to provide flood protection. 78 M li. 73mm? . . 1. 35'. mairuo .2141 $0040 h2u212<01u aWTinth! I . uh ix. A x?line =53: .. .uxon in . x. .52 (ESE: a . .. .1112-.. .. . .v3 tall toe-2.3.x .Euh Visit izk.3, 3.. 532.2. his (Exehtan. ?30 a 3x?3?u81 22.. oxn nxnyiu (.3 wk on x4 Ench? ?3 3.1051 um; .4: 3 B. 0. . 9325V335 x. ?Suuww an ?any: {So flu SHE QV .u?Nw. ii A .x on 10.59:: a? nu mt: .On c5913! ntusic (no; for. tniehtuvx .390 xx?. x. . in? .. .NW- ??tcux ??lu Esshx 3.. .188 Qn\_m rmw44ozwomw2w ruamnw szzah oz_N_J_m oz< mum?2.0.10 Figure 68. Diversion Tunnels Nos. 1 and 2 DrofI-Tube Arrangement 80 Because of its position (buried under the dam embankment) and its low irregular shape, the core block as a whole did not lend itself to a simple structural analysis. Little information was available at the time of design on stresses that might be imposed on the structure by the zoned embankment. However, the parapet was recognized as the critical component. It was determined that, with certain assumptions made for embankment soil properties, the parapet would tend to separate from the remainder of the block. Under one loading condition, the parapet was the toe of the 1.6:1 downstream toe of the 1964 cofferdam. Compressible Zone 4A was included upstream of the rigid core block to provide some room for base spreading of The other loading condition had three contributing factors: (1) embankment base spreading caused by the core block being upstream of the crest, (2) tendency of the embankment loads to arch across the core, and (3) projection of the parapet. Instrumentation was provided in the core block, particularly in the parapet, to observe stress and strains under these loading conditions. The parapet survived the first condition but cracked under the other, as is explained in the section on construction. The core block contains an extensive gallery system. The grout gallery extends through the upstream portion. A bypass gallery connects it to a gallery that was constructed to provide access to the underground powerplant. Later, this connection was plugged to separate the dam gallery system from the Powerplant in case either flooded. A recess off one of the galleries contains one of the dam structural performance instrumentation terminals. Also included is a drainage system with three pump chambers. Two of the chambers contain SO-horsepower, vertical, turbine pumps with encapsulated windings to protect against water damage. The third contains a 75-horsepower submersible pump. A level control consisting of electrodes is located in a well within the No. 2 pump chamber. The this slope. submersible pump motor starter and a duplex sump pump controller are located at the connection of the grout gallery with the powerhouse emergency exit tunnel. All three pumps are connected to a 16-inch discharge pipeline. This pipeline uses the tunnel for- merly connected to the Powerplant and galleries as the route to the terminus in the crown of Diversion Tunnel No. 2. Grout Gallery The reinforced-concrete, 5-foot by 7-foot, grout gallocated under the core from the core block up the right abutment to approximate elevation 780 feet and up the left abutment to approximate elevation 820 feet. From these locations, each leg extends to the downstream face of the Dam (Figure 59). Under the core, the gallery generally is in a trench approximatelery is ly 15 feet deep with some a 10-foot bottom width and '/:! imperfect and the concrete projects a few feet into the core. The side slopes. In areas, the trench is reaches extending downstream start the same as under the core and end fully projecting into the embank- ment. Purposes of the gallery were to ( 1 ) reduce the conflict between the grouting and embankment-placing operations, (2) provide an exit for the foundation drain holes, (3) provide the capability to regrout under the higher portions of the embankment if necessary, and (4) provide access to the core block gallery system and the facilities located therein. Based on economic considerations, the grout gallery was terminated before it reached the crest of the Dam. It was determined that the remaining 100- to 150-foot height of dam remaining on the abutments did not justify the cost of the additional length of gallery. The gallery in the trench is lightly reinforced considering the embankment loads on it, compared to structures designed using approximate methods. It was analyzed at the University of California using one of the first applications of the finite element method. Internal stresses and reactions of such a structure depend to a great degree on the relative stiffness of the concrete and the foundation rock. The finite element method readily handled these variables whereas other techniques available at the time could not. The result was a much more economical structure than the previously planned projecting gallery that was being analyzed by conventional methods or an overreinforced trenched gallery. More than six years of satisfactory performance have proven the validity of the analysis. Tunnel Systems A multiplicity of tunnels was required in conjunction with the construction and operation of Oroville Dam and Edward Hyatt Powerplant (Figure 68). Construction of the tunnels was accomplished under four major contracts. The first diversion tunnel and the Palermo outlet tunnel were let under separate conThe contract for the dam embankment included construction of the second diversion tunnel along with connecting portions of the powerplant draft-tube tunnels, a portion of the river outlet access tunnel, and the core block access tunnel. Tunnels directly serving the underground powerplant were constructed under the initial contract for the Powerplant. These tunnels, which include the powerhouse access tunnel, high-voltage-cable tunnel, penstock tunnels and branches, and the remaining portions of the draft tubes, are described in Volume IV of this bulletin. All tunnels were excavated in the moderately jointed metavolcanic rock of the left abutment. A series of drill holes was used and exploration adits were excavated to locate major shear zones. The location of tracts in 1961. the powerplant machine hall, the major underground excavation of the complex, was established on the basis of this exploration. Location of the machine hall, in turn, was a major factor controlling the layout of the tunnel systems. 81 All tunnels in the complex are concrete-lined. The designed concrete-lining section is that thickness between the inside tunnel surface and a designated line called the "A" were allowed In this thickness, no materials remain permanently which would line. to reduce the integrity of the concrete section. No rock was allowed to project into the section, and all timber was required to be removed prior to concrete placement. Structural-steel tunnel support and other metalwork, which did not interfere with the reinforcement steel, was allowed to remain in the section. Overbreak was anticipated in the excavation of the tunnels and a designated thickness of excavation and concrete lining (9 inches in the case of the diversion tunnels, 6 inches or less for smaller diameter tunnels) was paid for outside of the "A" line. The limit of payment was designated the "B" line. Diversion-Tailrace Tunnels. The alignment and two 3S-foot-diameter, 4,400-foot-long, diversion tunnels were selected to (1) bypass the dam profiles of the construction area, (2) provide for convenient connection to the underground powerplant for use as tailrace tunnels, and (3) keep the total tunnel length to a minimum. A circular section was chosen for the tunnels since they are subjected to high external hydrostatic heads. Diversion Tunnel No. 1, nearest the Feather River, has an intake invert elevation of 210 feet and an outlet invert elevation of 182 feet. The center reach of the tunnel is depressed to permit connection of the drafttube tunnels from generating units Nos. 3 through 6. The intake invert of Diversion Tunnel No. 2 is at elevation 230 feet and the outlet invert at elevation -207.5 feet. Draft-tube tunnels from units Nos. 1 and 2 connect directly to this tunnel and surge openings for units Nos. 3 through 6 are provided. More than 50 years of good streamflow records were available on which to base the design of a sequence to provide flood protection during construction. They indicated the normal start of a 4'/2-month flood season was November 15. The following covers the highlights of the sequence as it actually occurred: 1. Diversion Tunnel No. 1 was completed in November 1963 allowing embankment to be placed in the stream channel upstream of the core block. Had the riverflow exceeded about 12,000 cfs that winter, this embankment would have been flooded and the core block parapet would have acted as a weir, preventing erosion of the embankment material already placed. 2. Diversion Tunnel No. 2 was completed in November 1964 in time to combine with Diversion Tunnel No. 1 and the 400-foot-high cofferdam, to protect the Dam from actual floods up to the U.S. Army Corps of Engineers' standard project flood (frequency about 1 in 400 years and about twice the flood of record). As discussed later in the section on construction, this combination withstood a new flood of record. 3. When no longer needed for diversion, the tun- 82 nels were plugged upstream of the reaches utilized for the tailrace. Plugging of Diversion Tunnel No. 2 took place in August 1966, when the embankment was high enough to protect against the standard project flood with only Diversion Tunnel No. 1 functioning. 4. Tunnel No. 1 was plugged in November 1967 when the embankment was topped out and the spillway essentially was complete. Gates were lowered at the intake to Tunnel No. 1 to dewater the tunnel for plug construction. This act marked the beginning of filling Two Lake Oroville. criteria were considered for determining the size of the tunnels: (1) the flood conditions just dis- cussed, and (2) the most economical diameter for use as a tailrace for power generation. The two 35-footdiameter tunnels were required to control the design flood while holding the embankment placement rates to reasonable quantities. The most economical tailrace was estimated to be 3 1 feet in diameter but would have required a tailrace surge chamber. The two 35-foot tunnels allowed one tunnel to flow free and, by interconnections, eliminated the need for a surge chamber. As velocities during diversion would reach over 100 feet per second, special effort was required to ensure a high-quality surface for flow. High-strength concrete was used, and a concrete finish was specified which allowed no abrupt irregularities and only minimal gradual irregularities. Tunnel intersections were plugged with the inside surface smooth and monolithic with the tunnel interior. The only irregularities allowed in the diversion flow path were the gate slots in the intake structure for Diversion Tunnel No. 1 and in the exit portal structures for both tunnels. The slots were constructed with offset downstream edges to minimize turbulence and negative pressures in the slots. mouths were used at each tunnel to reduce inlet and prevent cavitation of the adjacent tunnel lining. Because Diversion Tunnel No. 1 required closure gates, a rectangular bell was formed and transitioned to the circular tunnel. Hydraulic model studies of the tunnels were conducted by the U.S. Bureau of Bell head loss Reclamation at Denver, Colorado (see Bibliography). Both diversion and tailrace modes were tested. The concrete tunnel lining was designed for the external hydrostatic head expected. Upstream of the plug locations, this was the maximum construction flood pool head minus the hydraulic gradeline for the peak diversion discharge (equivalent to velocity head plus intake head loss). Between the plugs and the dam grout curtain, full hydrostatic pressure of Lake Oroville would come to bear. Drain holes were therefore drilled through the lining into the rock to reduce local pressures, and an external loading of 50% of the lake head was assumed for design. Downstream of the grout curtain, the drain holes were continued and external hydrostatic head was assumed equivalent to the height of overburden. Any load from the disturbed surrounding rock was assumed to be maximum i borne by temporary supports and was not added to loading of the concrete lining. Structural concrete for the lining was specified to attain an ultimate strength of 5,000 psi in one year. The one-year strength was specified since full loading would not occur until the reservoir filled. Nominal reinforcement was used to minimize cracking due to shrinkage and temperature changes. All portions of the tunnels are contact-grouted to ensure good contact between tunnel lining and the rock. Pressure grouting from within the tunnel included continuation of the grout envelope constructed around the Powerplant and consolidation grouting of the rock immediately surrounding the tunnel plugs. The grout envelope involves radial holes on a regular pattern throughout the reach near the Powerplant, grouted in an interval between 40 and 50 feet from the tunnel lining (Figure 69). After the 150-foot-long concrete plugs were placed near the center of both tunnels, the knockout plugs for the draft-tube tunnel connections then were removed. The draft-tube connections, 18 and 21 feet in diameter, had metal form panels to partially outline the knockout plugs, facilitating their removal and minimizing the roughness of the opening. a Large ports connect Diversion Tunnel No. 2 with 3, 4, 5, and 6. This allows Tunnel No. 2 to act as a surge chamber to receive water from or supply it to the draft tubes and Diversion Tunnel No. 1 during load changes. Tunnel No. 2 operates at atmospheric pressure during all powerplant operation modes with the flow normally half filling the tunnel. To provide atmospheric pressure to the upstream end of Tunnel No. 1, an 8-footdiameter pressure-equalizing tunnel connects the tailrace tunnels directly downstream from the tunnel the draft-tube tunnels of units Nos. plugs. Maximum discharge through Tunnel No. 1 during generation is 12,000 cfs (picking up flow from units Nos. 3 through 6). Discharge through Tunnel No. 2 is 6,000 cfs (units Nos. 1 and 2). River Outlet. The river outlet is located just downstream of the plug in Diversion Tunnel No. 2. Two 72-inch-diameter steel conduits were cast into the plug. Stream releases are controlled by two 54inch fixed-cone dispersion valves that are backed up by 72-inch spherical valves. Access to the valves is gained through a tunnel from the Powerplant. The river outlet valves are capable of a combined discharge of 5,400 cfs with full reservoir. A steel liner is used inside the tunnel where discharges impinge and a baffle ring protrudes into the flow path to help still the discharge. An air supply for the valves is provided through a small-diameter tunnel above and parallel to the tailrace tunnel. This tunnel allows air to be drawn by the valves from an area downstream, clear of the valve discharge turbulence. The 72-inch, spherical, shutoff valves have double are hydraulic cylinder-operated, and are designed to sustain the maximum transient pressure without exceeding the allowable design stresses. The seats, valves are provided with an electrohydraulic activating and control system. Each seat is separately controlled and operated by oil. The operating controls are arranged for the following operations: 1. Normal opening and closing of the valve and upstream and downstream seats from the valve chamber at elevation 233 feet. 2. Emergency remote closing of valve and downstream seat from equipment control chamber at eleva- tion 290 feet. The 54-inch fixed-cone dispersion valves (HowellBunger valves) are actuated by electric motors which can be operated locally or remotely from the equipment control center. Additionally, handwheels were provided for emergency operation of the valves. The valves were carefully designed by the Department because of the severe service expected and the history of problems with similar valves experienced by other agencies. Special consideration was given to vane design; stiffness was emphasized in order to reduce any tendency toward vibration and possible fatigue failure. Smooth ground surfaces and faired edges of components exposed to high-velocity flow and full-penetration welds throughout were specified. Extensive nondestructive examination was performed all welds during the construction phase. Hydraulic model studies of the river outlet were conducted by the U.S. Bureau of Reclamation in Denver, Colorado. on Diversion Tunnel Intake Portal Structures. Intake excavations were shaped to efficiently train streamflows into the tunnel intakes during the diversion mode. Cut slopes in overburden were laid back to safe slopes to preclude slides, and steep cuts in rock were rock-bolted and covered with heavy wire mesh. The plan of the intake structures is shown on Figure 70 and sections on Figures 71 and 72. The intake structure of Diversion Tunnel No. 1 is a rectangular bell mouth transitioning to the^5-foot- diameter tunnel. A center pier with an elliptical nose is incorporated into the structure to accommodate steel bulkhead gates to dewater the tunnel for plug placement. The gate slots are positioned as far back on the transition as practical to take advantage of arching of the partial circular section and thus its ability to resist external loads. Horizontal prestressed rods were installed in the pier and attached to the gate-slot assembly to carry gate loads forward to the more massive pier section. This assembly consists of 1-inch steel plates lining the slot and a steel grillage connecting downstream slot faces so as to carry gate loads to the prestressed tendons. Heavy plate was used for the slot liner to maintain true alignment of the bearing surface and slot liner after prestressing loads are apthe plied. 83 84 94-1; at 1.. u: a: y?mwlm n? lot25-; u: m. m, 01>" {004) "an: a {9 (an: no: 1 a: 4.4 Amy! . L. 4??1 ., luvi?v??z-v r? 2M lava wv M1 A's-Inuit w?Q?o?N?hvviviJM ru In an - 1 fairy; I no (vb? PROFILE ENVELOPE ?nal/7M4: . 5a.) Figure 69. Grout Envelope In[mom pm{Awrupwx?anau J- mm. rt~uw~7~n~ .1111] nuv?n510~ roman ENVELOPE GROUTING SECTIONS ?yaw/nu?! ~?u/nuamya M-dv? Wuvm uv? ?n UL, ?jfx-Ls- "Vi; - 59 1m mum 53?? um 7? annanunyp?a-n-b 5? ctr-nun.? I?ld' hunt??cau?mm-wm-muu .- K. -.13- in? lnfuke Structures Plan 85 86 .In an": m? )Mnnon ram: w'r/o II 9 ll Jca'o 05744 2' 3:11): Figure 71. Diversion Tunnel No. I I 'I/a lr-D' ll ??40 WALL 5-5 SECTION C-C I?Intake Portal Sedions 6 I. 2/9 c. le?Jr nm- in Jul r-r ?4 In.' 'aas "la a' .- Wan/41.1 ~510M4u VIEW man I All? N549 3/65 5/554 .756 I -l ly?sal 'I/a 5/ (D 1: Pan ball.? an ?mm (90 5 Anna? M, grew-J we! an" pillor" v5 'do . t-F SIDE 5755? if; 7/0? 1-1 mum: ru Won Thou? tr? Lia/Mutual - 4 l?h?nlh to? a. n/ at lb.? (?900? ind m- mum an: I .ru/ ?1 ha?. m? ?an 9 5' amn- 41/ ?as? uni-n tumor! Io Can/rt! armam Imp-gm hula-v "Ian-v ?My "unr- :Icp~ cum par/a! far cant/Mr emu-I- a now (v mm, ca? ?Ia/1 ?-mwnmul a. law a: min :M/rar/ Mr Inn 8 mm Jr-a' (norm GIMI pha- no 0-, 1-005 -I (in! at"! "Iowan! mola/ amm no 16:! any . Hut 000 pm?! ha .y ww- Mum ll Imm- par/u .Ilruh/i ml?oh?n i. you? may? uni/nu )9?m?m a 1 a ?mu 11.! :1 Mn nun-w nun-mun an wuu luau-cu own-rc- a up. no (xx-1W nu.? mu noun Mount amm- WVILLE OAI DIVERSION YUNNEL NO I COICII INTAKE PORTAL v: a cum: Jun-n :bpranro "up! .Am Amy: Ina: at (ram-hr: dun/In bat an.? 9 87401 Figure 72. Divers: on Tunnel No. 2?lnioke Portal Sect lOnS 87 S, Ayn/mu, {PI/alr? I WPPR F. 0 7? ?72] [7.1/37 ?17] a 3 7 N?su'hr/M A: dream cm r: fun-u 754&1 ?aim/i: mpg/10?? vg'nu- 2.10 [5 2:4 7 - 1 (62" - .r 477/ yrvv-l?r?nr! . 1 i 1? w??w "r . an ?u-m'lut . aware? 9. v.9-ra .v m, Aq?: SECTION {y to, mu 1.. 0w Jam-9; . -2 luv! - emu lunac- WVILLI on: DIVERSION TUNNEL no.2 IITME KCTIONS Inn-all )1 uncou r"lg/um 1mm 4mm 11-5 l0-5 The closure gates, 17 feet - '/J inches wide by 36 feet 6 inches high, were built up from wide-flange structural sections and provided with rubber seals. They were positioned in a chimneylike structure above the gate slots prior to closure and lowered into place by a frame and cable system. Low streamflows were necessary to allow gate seating. A trial lowering was required for each gate, prior to final closure, to ensure that adequate sealing could be accomplished. The intake walls and roof of Diversion Tunnel No. 1, upstream of the gate, were designed for an external hydrostatic head equal to the velocity head plus the entrance head loss during peak discharge while diverting the standard project flood. The closure gates and the structure downstream of the gates were designed for the maximum water surface in the reservoir during plug construction. Normal working stresses occur with a load of 440 feet of water, and yield is not exceeded with a full reservoir (elevation 900 feet). Diversion Tunnel No. 2 intake is a circular bell mouth. The headwall and wingwalls are anchored to the rock face with grouted No. 1 1 bars. No provisions for gating were required as the intake is 20 feet higher than Diversion Tunnel No. 1 and was out of water during construction of the plug and river outlet (Tunnel No. 1 remaining open during this period). A concrete trashrack was constructed at the intake face to guard the river outlet valves from submerged debris. An auxiliary intake for the river outlet was placed at elevation 340 feet and connected to the tunnel by an 18-foot-diameter shaft. This intake supplies water to the river outlet should the tunnel intake be closed by silt. This intake also is provided with a concrete trashrack. The trashracks are designed to withstand a differential head of 20 feet. Diversion Tunnel No. 2 with the northern end of the powerplant machine hall. The 8-foot-diameter tunnel extends from elevation 262 feet in the powerhouse to the river outlet control chamber at elevation 290 feet, an enlarged portion of the tunnel which contains the control equipment. It continues to an 8-foot-diameter reach extending from the chamber to the diversion tunnel (invert elevation at intersection-elevation 233 feet). Metal stairs were installed in the inclined portions. The control chamber enlargement is 1 5 feet in diameter and 3 3 feet long. It was placed at elevation 290 feet to preclude flooding of the powerhouse with maximum tailwater during spillage of the maximum probable flood (maximum water surface elevation 287 feet) A panel downstream of the valve chamber is designed to pop out when a head of 15 feet bears on it; thus, the tunnel will not serve as a passage to flood the powerhouse should a failure of a river outlet component occur. The concrete lining is 22 inches thick in the valve control chamber and 12 inches thick in the 8-footdiameter tunnel. The lining will support the external hydrostatic head of full reservoir. As the tunnel is within the zone of influence of the powerplant drainage system, the actual head on the structure will be . somewhat less. Powerhouse Emergency Exit Tunnel. The purposes of the powerhouse emergency exit tunnel, shown on Figure 74, are to provide an alternate means of escape from the underground powerhouse in case of emergency and to act as an access to the grout gallery from the powerhouse. This tunnel, 8 feet in diameter and approximately 570 feet in length, is discussed in Volume I\' of this bulletin. Core Block Access Tunnel. Diversion-Tailrace Tunnel Outlet Portal Structures. Both tunnels have similar outlet portal structures consisting of a concrete headwall and a 50-foot-long concrete trough with a semicircular invert (Figure 73). Gate slots are provided in the troughs for installation of a bulkhead gate to dewater the tunnels. The gates extend from trough invert to normal tailwater surface, elevation 225 feet. The troughs are anchored to the rock with grouted bars and are designed to resist the forces of external head to elevation 225 feet with the interior dewatered. The headwalls also are anchored to the portal face with grouted bars. These bars are designed to resist a 10foot hydrostatic head behind the wall. Above the headwalls, working areas and concrete on which trashrack hoisting equipmounted. The trashracks are held above the troughs on the portal face during generation of power and lowered into slots provided in the trough during the pumping cycle. Design of the trashracks is covered slabs are located ment in is Volume IV of this bulletin. River Outlet Access Tunnel. The river outlet ac- cess tunnel (Figure 74) connects the valve 88 chamber in The purpose of the core block access tunnel is to convey seepage water from the core block to Diversion Tunnel No. 2. It is a former exploration adit and was a planned low-level connection between the core block and powerhouse. It was plugged near the powerhouse wall to reduce the chance of flooding in either facility due to this interconnection. The tunnel is 7/4 feet in diameter and approximately 780 feet in length. A 16-inch-diameter steel pipe was installed in the tunnel to convey discharge from the core block drainage pumps. This pipe terminates in the vertical hole above Diversion Tunnel No. 2. The tunnel will convey water from the core block to the diversion tunnel should a failure of the drainage pumps occur. The concrete tunnel lining is 10 inches thick. This thickness is sufficient to resist the external hydrostatic pressure of full reservoir and yet be convenient for placement of concrete. Palermo Outlet Tunnel. Because the construction terminated the previous method of supply to Palermo Canal, a tunnel outlet (Figure 75) was designed to make releases into the Canal downstream of the Dam. of Oroville Dam -55 ^^;\ a" I I I I I U"' f ' I J Figure 73. Diversion Tunnel Outlet Structures — Plan I I -J and Sections 89 Figure 74. Mistellaneous Tunnels I. Canervh whim 1 0w rwvul '1 (A [c I awn! Amvv rm! am In? . "183-09! 4' a! h-v In?! Cow." *nln max, rum: In 1v v' PLAN . am: 7:50 >4 mm In". Mall In My." wen. Saw rum! {we} a Dim-Inn 7000'! a: IC) [1 2.9300 nu' Emu-yo K, [m 7.?va mu am I Uln?l?? Mm ?a 4* Iwc; I cm: cwPon'r Pm?: cannon WI lineh? NICK :00 1 arm am, ~Ic; a" A-l' 1 4w- Ivan,- us. .1 5-, 104' .- Jan Na SAFE Nae-our WATER mu .- mac?- n. a cum ovumnm 0' warn anon-cu at we mm mm In" nm-v-u Olav-Lu ammo- OIOVILLE POWER PLANT MISCELLANEOUS TUNNELS PLAN AND rift?? ?arm 0-.- ..Mwu n. . a row? a "w Figure 75. run?. .r tum-Wanna? mum (Mir-nu. -(m7y mm.? 5-000 1? suaf32/949 Inca (1?00 Mica AIM lama limo lama mma Nvoa 11:00 2060 SM Palermo Ou?et Tunnel Emmi-l mm! m: fat mun-my Sn 0-00 91 24-00904. 5-5 pm- SECYIUIV 0-6 CWTAIM r- Emmi [?7le lrt?oW/V an!? an. 2900 24:00 :1100 26'05 5567/0? A -l oulm um ?can: Divide i (\Myr?r 1: aum m4 Inrfcad cf Gal/Form Pan. a All ?mam. r/(Immhd 'gopr of mm mm?, 9.. hf~r ar 55? Bit. ?'anl .u a, m. rm anmm? $19: 3/ war av?. amour. Wm "nu/m - ?or-[7 4 him. if Irv/54L rag: r: a! Ill 905717400 MIN "rod ?'00 :nao Jeaoa ?Mn ?Ian :5 00 ml and when ra Mammy. 4b ?yam BUILT 12mm: 5567/JUWPIKD (Jet?? ID 577! bilf??fi?ff? FRH/fij/??m 40 m; nun if}! PF NC {-11 Ia Anyway ,:yncall 'm .m ~Mr?ryrl I: wr 4v than?, ["1ka mm um! .41 pm if in.? x! a a 1 n- ?an 'uno Euurun a ?r 'Il'Wa INK. 0mm mu mus-o- MLE on In mm WTLET gm- Sui FUN. In ?Clu 91 - mn- an. A-noq?I 3 The outlet tunnel concrete-lined and is approxiintake portal invert is set at elevation 548.25 feet. A 6-foot-diameter level tunnel connects the intake with a valve chamber located immediately downstream of the intersection with the dam grout curtain. Downstream of the chamber, a 6-foot - 6-inch horseshoe section continues to the downstream portal on a slight downhill grade. A wall divides the downstream reach into a water-carrying passage and a 3-foot-wide access walkway. The outlet valve is connected to a steel conduit which is embed- mately 2,430 is feet long. The ded in a concrete plug immediately upstream of the valve chamber. The intake portal structure consists of a short length (approximately 27 feet) of cut-and-cover tunnel section with invert elevation 549 feet. Slots are provided for a trashrack and bulkhead gate and a bulkhead gate is held in place above the intake. To dewater the tunnel, a diver is required to connect a hoist rope to the gate and remove the pins which hold the gate in its storage position. Tunnel lining upstream of the dam cutoff was designed to resist the external hydrostatic head of full reservoir. Downstream reaches were designed to resist the maximum pressure used during tunnel grout- This was assumed to be 25 psi. Drain holes were through the lining in the downstream reach to ensure that ground water pressures on the lining do ing. drilled not exceed this design pressure. A grout curtain is provided upstream of the valve vault to mesh with the curtain under the Dam. The outlet facility in the tunnel consists of a 12inch-diameter rated discharge valve backed up by a 30-inch-diameter butterfly valve. Discharge is made through a steel hood into an energy The downstream dissipator. portal structure consists of a con- and wingwalls paralleling the channel to retain material which may ravel from the cut slopes. Immediately downstream of the portal, a reinforcedconcrete Parshall flume with a throat width of 5 feet was constructed in the channel and equipped with a crete headwall recorder. During construction of Oroville Dam, water for Palermo Canal was obtained from Oroville-Wyandotte Irrigation District's Kelly Ridge penstock, which is approximately 2,600 feet downstream of the outlet portal. A 16-inch turnout pipe connects to an access door in the penstock (elevation 583 feet) approximately 240 feet northeast of the point where the penstock crosses the Canal. The buried turnout pipe terminates near the Canal with a 10-inch-diameter, 40-cfs, rated, discharge valve enclosed in a reinforcedconcrete energy dissipator. The valve is located at elevation 547 feet. If, in the future, there arises some emergency situation where water becomes unavailable from Lake Oroville in the required quantity, the needed water can again be supplied by Kelly Ridge penstock. 92 The same outlet requirements of this turnout are the as for the outlet tunnel, charge of 40 i.e., a maximum dis- cfs. Spillway spillway for Oroville Dam (Figure 76) is locaton the right abutment of the Dam. This location allows spillway discharges to enter the River, well downstream of the toe of the Dam and powerplant tailrace. The spillway consists of a combined flood control outlet and an emergency weir. The flood control outlet consists of an unlined approach channel with approach walls shaped to make a smooth transition to the outlet passage, a headworks, and a chute. The headworks structure (Figure 77) has eight outlet bays controlled by top-seal radial gates, 17 feet - 7 inches wide by 33 feet high. A concrete chute (Figure 78), 178 feet - 8 inches wide, extends 3,050 feet from the flood control outlet down the side of the canyon to a terminal structure (chute blocks) where the water plunges into the Feather River. The emergency spillway is an ungated, concrete, overpour weir located to the right of the flood control outlet and is made up of two sections ( Figure 79) The right 800-foot section is a broad-crested weir on a bench excavation. The left 930-foot section is a gravity The ed in a natural saddle . ogee weir up to 50 feet in height. Except for a narrow strip immediately downstream of the weir, the terrain below the weir was not cleared of trees and other natural growth because emergency spillway use will be infrequent. The flood control outlet was sized on the basis of limiting Feather River flow to leveed channel capacity of 180,000 cfs during occurrence of the standard project flood (peak inflow 440,000 cfs). This limitation applies at the confluence of the Feather and Yuba Rivers approximately 35 miles downstream of the It was estimated that a runoff of 30,000 cfs could be expected within this 35-mile reach of the Feather River during the standard project flood. Therefore, the flood control outlet was designed for a controlled release of 150,000 cfs. The normal reservoir water surface previously had been set at elevation 900 feet. To meet these criteria, a flood control reservation of 750,000 acre-feet was needed. The criteria also governed the size and location of the flood control outlet gates. The outlet must release 150,000 cfs at water surface elevation 865 feet to control the flood shown on Figure 80. The standard project flood has a probability recurrence interval of approximately 450 years. If data received indicate a flood is developing greater than the standard project flood, release through the flood control outlet may be increased above 150,000 cfs but may not exceed 90% of the inflow. When the reservoir fills above elevation 901 feet, flow occurs over the emergency spillway. The emergency spillway, in conjunction with the flood control outlet, has the capacity to pass the maximum probable flood release of 624,000 Dam. drainage area (peak inflow 720,000 cfs) while maintaining a freeboard of 5 feet on the embankment. The maximum probable flood has a probability recurrence interval in excess of 10,000 years. Hydrologic and hydraulic data are shown on Figure cfs for the 80. \'arious types of spillways were studied and mod- The original design consisted of a control structure with radial gates to pass the total spillway design flood. A short coneled to arrive at the final structure. apron was to extend downstream from the conand then the flows were to be turned loose down the hillside in an excavated pilot channel. As the spillway would operate on the average of every other year, this plan was determined to be unacceptable based on the large quantities of debris that would be washed into the Feather River and could ultimately affect power operations. Adding a converging concrete-lined channel and chute to the original headworks structure created major standing-wave problems throughout the system. These problems were resolved by separating the flood control structure from the spillway structure as shown on Figure 76. crete trol structure, The rating curve for the flood control outlet (Figis based on these hydraulic studies. Concrete for the spillway chute, weir, and flood control outlet structure above elevation 865 feet was specified to obtain a strength of 3,000 psi in 28 days; concrete for the lower portions of the flood control outlet, below elevation 865 feet, was specified to obtain a strength of 4,000 psi in 28 days; and concrete immediately behind the prestressed trunnion anchorages was specified to obtain a strength of 5,000 psi in 28 days. ure 81) Steel reinforcement conforms to intermediate or hard-grade billet steel as specified in Designation A15 or A408. Post-tensioned tendons for the gate trunnion anchorages have an ultimate strength of 160,000 psi. Structural steel for the main members of the radial gates and bulkhead gates conforms to Designa- ASTM ASTM tion A441. Secondary gate members and trunnion beams are of A36. Head works. The top of the 570-foot-long headcoincident with the top of the Dam (elevation 922 feet). The gated outlet passages are placed in an excavated channel depressed from the emergency spillway approach channel. The invert of the outlet is works is elevation 813.6 feet. Four bridges or service decks are provided: the crest of the structure is a roadway used for maintenance purposes, including placement of stoplogs; the radialgate hoist deck is at elevation 886.5 feet; the spillway road bridge providing access to the right abutment by way of the dam crest is at elevation 870 feet; and a walkway for inspection of the gates and trunnions is at elevation 847 feet. Because the headworks structure is founded on competent rock, sliding was not considered a factor in stability. The structure was analyzed for safety against overturning. The embankment grout curtain was extended under the headworks. It consists of a single line with a maximum depth of 50 feet. Drain holes were drilled into the foundation rock downstream of the grout curtain. Uplift pressures were assumed to be 100% of reservoir head at the upstream edge, reducing in a straight line to 33% at the drains and zero at the downstream toe. Reinforced-concrete piers, 5 feet thick, separate the gated water passages. The piers also support the breast wall and service decks and provide anchorage for the gate trunnions. The pier noses are steel-armored to reduce wear, and guides for stoplogs are welded to the leading edges. The crest service bridge is made up of reinforcedconcrete slabs spanning between the piers. The total width is 21 feet. The spillway road bridge deck is of similar construction but the total width is 34 feet. Reinforced-concrete bents were required on the downstream end of the piers to support the bridge. The maintenance deck involves individual reinforced-concrete slabs, 18 inches thick, supported on the piers in 4-inch-deep notches. Blockouts are provided in the deck for access to ladders which lead to the gate head seal assemblies. It was designed for a live floor load of 250 pounds per square foot. In addition to the live load, a seismic acceleration of O.lg parallel to the axis of the structure was investigated assuming the deck acts as a strut between the piers. The hoist deck, a downstream continuation of the maintenance deck, was designed to support the weight of the gate hoists, the maximum force caused by lifting the gates, and a live load of 250 pounds per square foot on the working surface. The walkway for inspection of gates and trunnions, a 15-foot-wide reinforced-concrete slab spanning between the piers immediately downstream of the gate trunnions, also was designed to support a live load of 250 pounds per square foot. The skinplates for eight 17-foot- 7-inch by 33-foot were designed as a continuous spanning horizontally between vertical supporting members. Bending stresses in the plate were determined by treating the member as a continuous beam; however, horizontal tension also was checked. The load on the skin assembly is transmitted to the trunnions through horizontal girders and canted arms. The outlet gate trunnion assemblies consist of weldedsteel trunnion rings to which the three end-frame top-seal radial gates plate struts are connnected, steel shoes rigidly attached to the piers (e.g., by a trunnion beam), and trunnion pins. Adjacent trunnion pins are not interconnected to the pier anchorage but are connected to a common 93 ma: I 7d ?punt-n uouvmu: unv 1vu3N39 "-11:43 "a anuouo lemma rnmcEdit-r I 0m M: cat" an In, mu,? . ?an na- 4aml~r\b rum-.576? b? .7 I I 1 "we/allOva/41) sic wan . I nun: - a?a Figure 76. General Plan of Spillway 94 95 Figure 77. Flood Conirol OutleI?Flan and Elevo?In,? 1-35 -2 F. ?D?'nuh cum-I [m a. 1 95' ?2 ?ygru'th won Dam Am .5 45?Ja?aa': Aura-en wall a m. 31-: 4 Alana/yin numnu nan-u; I I I1 Far my Aral ur-wo ?4 A :?auharhnn lam! - ,5 51an?? I NICI Mars! pm. emu ul? an?. page 95'- 9.75 v7 {555-34 A accrue a) . 1 LC inn-:3 ,2 il- I l?mammar- Jnmu/ I PLAN San/o 25Mann/mi {qua - gringo/Lin. I 14:45 am numb!" a A "um, . ?nd any. 9.. human 5., ., . - m. 51.. 51., own In. an? U'?trarnnf "a 0.17 5-13 u- I'Padm/ gain no! .vhalvn Iowa Inca moo 19AM A A sun In A 5:147. nun??v 179" Chem Amt Gar: mu", ?1 on (wt?Kc Mir/h 04400' 4 mum/5m? V?tuv' SAFETY . Noe-nay .- WATER 27mg "mm. mm 0' tamer- mun-om or mu um. ncern DWISIOI onovm: mu SPILLWAV FLOOD CONTROL OUTLET pun no szvAnou Ina?nu mxfzI (I [In . It: .11: IA .. I I a 8.3. an uikbkl N: Sal ?83. 9.. also: .53; ?#320 5.44? lea 3439.0 39-35 13.5.8 if giv?lng .- I I I >huu112sz 5.. int.?ki waits InkIHNI HT If I II NARI IIRIPIWEFT I hVu II. I I I IIHII (IIJII I4 I I I I I Spillway Chute?Plan, Pro?le, and Typical Sections Figure 78. 96 97 Emergency Spillway?Sec?ans and Details figure 79. aw mm 7min mu '0 <2);er HM [Mow ear/M you if A calm (my a" 40 Ear/thud emu-u. o' war-rum at I 1 . [Col/?Mm 1mm SECTION - (are 1506 on: 0/ i am?! can: a? ?09. madam-n ?cum/an Dru/no] 9 If - . Apron\ 1 DLAN Scalo Spa/(my can Err. par 00 SECTION C-C Nor re Sean: Smcing a! div/HI ppm/.1 dimer/m or ?aw: . are .25 5'0. 2?75 - 27am: Nil"! pl-(O {Intr-I' 4h nanny rum 1' . IO. at"; \Wcod (Ir 51?: DPA IN DE TA 330/. -I 30.0' Memo? uv.S Figure 114. Transfer Conveyor 127 abutment contact material, with not less than 60% minus No. 4 sieve size, generally was manufactured on the embankment by running Zone 1 material over a portable vibrating screen. Zone 2 serves as a transition filter zone between the impervious Zone 1 and the coarsegrained Zone 3. This material is a combination of gravel and sand occurring naturally in the borrow areas or produced by blending the underlying sands with the gravels. Placing and compaction of Zone 2 were similar to Zone 3. The one exception was that fine-grained the maximum paction. lift To impound stream Zone thickness was 15 inches after com- and measure seepage into the down- embankment 3 at elevation 242 feet, a was constructed of Zone lA material. Zone 2A filters Zone 1 A. Materials and placing procedures were the same as for Zones 1 and 2. Zone 5A, a horizontal drain, was constructed at elevation 235 to 245 feet from downstream Zone 2 to the downstream face. Zone 5B, a vertical drainage zone 20 feet wide, was constructed immediately downstream from Zone 2. These zones were added after embankment construction was underway because there was small earth barrier concern over the amount of fines in the pervious material that was being delivered to the Dam site. To ensure that the downstream shell would remain dry, these zones were incorporated into the Dam. Zones 5A and 5B were placed and compacted in the same manner Zone as 3. A zone of riprap was placed on the upstream face of bankment reaching elevation 615 feet in the location grounding grid No. 2, the grouting subcontractor drilled four cable drop holes from the embankment foundation to the crown of Edward Hyatt Powerplant. Using a "fish" line, the drops were fed into the holes from the Powerplant and pulled up to the foundation level using the winch of a y^-wn truck. Prior to grouting the holes, the drops were supported from the top by wire mesh grips looped over 2-inch, schedule for pipe placed over the holes. Before grouting began, the bottom of the holes at the powerhouse crown were caulked. Using a small "tremie", about 25 feet of grout was placed in the bottom of each hole and allowed to set, forming a plug capable of holding the remaining grout needed to fill the hole. When the embankment reached elevation 615 feet, 80, steel grounding grid No. ing grid No. 1. 2 was installed similar to ground- Lighting and Power Systems. In the grout gallery, power system consists of a 480- volt, 3-phase, power distribution system which supplies power to each of the six electrical tilating fans. equipment panels and two gallery venA 1 /4-inch rigid conduit was installed throughout the gallery with pullboxes located at 200foot maximum intervals. Three No. 2 and one No. 12 insulated conductors were pulled into the conduit. The No. 2 conductor provides power, and the No. 12 conductor is used as a switch bus connecting each of the lighting push-button stations for common RHW lighting control. The 480-volt 3-phase and on power is supplied to the system from the Powerplant through a distribution downstream face of the mandatory waste area at downstream toe. Riprap for the upstream face was graded rock up to cubic yard in size. At the downto 2 cubic yards in stream toe, rock fragments from size were used. Most of the riprap was spillway rock placed as the outer 6 feet, measured perpendicular to the slope. The shot rock was hauled directly from the board located in the grout gallery at Station 36-1-75, the grout gallery connection to the emergency exit tunnel. Connected to grounding grid No. 1, a No. 4/0 bare copper ground cable was installed throughout the gallery system to provide grounding of all conduit and electrical equipment. the the the embankment from elevation 605 to 922 feet 1 '/j spillway to the Dam. Electrical Installation Electrical installation test grids work on Oroville of two grounding and the Dam consisted of the two and powcore block, and instrugrids along with installation of the lighting er systems in the grout gallery, ment houses. Grounding Grids. Grounding grids (Figure 115) were installed in two areas in the embankment as part of the powerplant grounding system and were connected under a completion contract covered in V'ol- ume 1\' of this bulletin. When the embankment reached elevation 290± feet, the area for the location of grounding grid No. 1 was bladed and "V" trenches were cut in the pattern of the grid. Electricians placed the copper cables in the trenches and cadwelded the cross connections forming the grid. Sand backfill was placed over the cables and embankment 128 operations continued. Prior to the em- Structural Grouting of the Core Block As mentioned in the discussion of the core block design, compressible Zone 4A material apparently limited upstream horizontal earth pressures on the unreinforced parapet protecting it through the initial loading condition. However, when the downstream fill was placed, pressures from that direction caused a rotation of the parapet and cracking as shown on Figure 1 16. The presence of cracking was first indicated in October 1965, when contact was lost with piezometer upstream of the core block at elevation 250 feet. to the piezometer had been routed through the core block concrete, near the top surface, and beneath the parapet. In April 1966, the last instrument routed beneath the "hinge point" was lost. Indications continued through the summer of 1967, although no adverse conditions were visible from within the galleries except for a joint in the sump which started leaking water at a rate of approximately 35 gallons per No. 8, Tubing 129 Figure 1 15. Electrical Grounding Grids Wm vpra. ru/ ?nd/u: 5nd Ann 290 wear My; . m, I: .. 14.1 If! L't/ad :p?lny me i 5., ?Wm??1 ?zraunil?y ?rm A prpra. a a: ?Nlr 1m SECTION A-A a'e azaa' . 3r: ?Imbon/tm'nf MGIINII I: myHrapl Ste Deb/l 1 .3e at": Fewer Plan I 4 '7 can): mm; rev; Iral' a, a, ?mum?, 5m: w: n. '0 11". man?'7? . wrap, f?bea Fawr? I A away rm? Appral a no ?3 air I "00' i?rl? we Dem11,117. ?47,375 4,557 any: A 51-1! MI. I: liil.? .nfr an! (*0th Lc? 4 "may I. 7'.ara/wn- ?inn ?Man-mate 70., 15?? a. Jule/ltd a - .m and 5-5/1 ?no a: ?fa It/or/J,3M ?w 5?1 ?61n?v? w- - )ov uvn numu 01va menu: on EMBANKMENT ELECTRICAL enounnmo run AND szcnons ?u .u 31: I 1mm? "?76164 Stream Flow Figure 116. Cracking of Core Block minute. Exploratory core drilling from the gallery system was initiated in the suspect area beneath the parapet wall. Open cracks, several inches wide, were estimated by drilling action and visually observed by a 20-foot-long periscope. To minimize any further disruptive movements which might be produced by future reservoir loading, and to prevent reservoir seepage into the galleries and through the core block, the cracks and all monolith joints in the core block were filled with a neat grout. Six thousand sacks of cement were injected under pressure into the interlaced cracks and joint system. The grout mixes used varied from one sack of cement for one gallon of water to one sack of cement for five gallons of water. Drilling and grouting were done in stages from August 1967 through February 1968. Final check drilling, with 450 feet of water head in the pervious zones acting on the core block, indicated the cracks and joints were effectively filled and sealed off from any significant reservoir seepage. The grouted cracks and joints were instrumented to detect any future movements. There has been only minor harmless movement in the five years since the instruments were installed. Diversion Tunnel No. 2 Diversion Tunnel No. 2 was excavated from the outlet portal to within 54 feet of the inlet portal to protect against possible floods. Open-cut excavation of the outlet portal channel began on January 3, 1963, disclosing that the left channel wall contained unsuitable rock; therefore, the slope was changed from Y^-.l to I'/::!- In addition, the left wall and headwall were both rock-bolted with expansion-shell groutable rock bolts before starting excavation of the crown drift. A 5-foot-square pattern with chain-link fabric and header steel was used. Thirty-foot-long crown bars (No. 18 rebars) were installed on 12-inch centers 2 feet above the tunnel "B" line and grouted. Excavation similar to that for the outlet portal was on the inlet portal in February 1964. Because of the extremely weathered rock at this portal, the contractor chose to drive an 1 1- by 1 1-foot exploratory crown drift through the 54-foot plug that was left in for flood protection. After a 1-inch-wide crack was observed over the portal at Station 3-1-20, the face was moved 3'/4 feet upstream in order to accommodate the revised structural support. The additional support steel and knee braces were anchored in concrete. Additional 15-foot rock bolts were installed above the portal face. Tunnel excavation resumed and removal of the rock plug was completed on July 31, 1964. started Tunnel excavation, concreting, and grouting were accomplished in the same manner as in Diversion Tunnel No. 1, except that the invert was concreted with a slip form and a steel liner was placed downstream of the river outlet location. To facilitate conversion of the tunnel into its role as a tailrace tunnel, the draft-tube stubs; auxiliary intake shaft and river outlet, air supply, and pressure-equalizer tunnels were excavated, lined, and capped off with removable concrete knockout plugs during the initial construction period. The main tunnel was completely excavated and lined prior to November 1964. Diversion Tunnel No. 2 was in service as a diver[ 130 sion facility for the winter seasons of 1964—65 and 1965-66. During the summer of 1965, draft-tube stubs Nos. 5 and 6 were opened up, completely constructed, and resealed. In the summer of 1966, Diversion Tunnel No. 2 was closed permanently by the installation of the mass gravity concrete plug. Streamflow continued through the adjacent lower Diversion Tunnel No. 1. Concurrent with this was the partial construction of the valve chamber and draft tubes Nos. 3 and 4 and removal of the knockout plugs from draft tubes Nos. 1, 2, 5, and 6. The knockout plugs for the auxiliary intake shaft and river outlet, air supply, and equalizer tunnels also were removed at this time. Installation of the last 14 feet of 72-inch conduits and the valves was delayed for the 1966-67 winter season due to manufacturing problems with the conduit and valves. This necessitated installing bulkheads at the upstream end of the conduits to prevent flooding of Diversion Tunnel No. 2 and constructing a blockout for the valves and a portion of the conduit at the downstream end of the tunnel plug. Wedge seats (Figure 117) for the plug were excavated from the tunnel lining by blasting. The deepest holes at the upstream end of the wedges were 1 foot, and succeeding holes progressing downstream in each wedge were shortened to develop the taper. All loose material was removed with chipping guns prior to placing concrete. Stainless-steel grout stop was installed around the full circumference of the plug at each end. This was done concurrently with the concrete work. Concrete was placed in seven lifts of varying depths because of the installation of the two 72-inch conduits in the plug. An 18-foot-long blockout was left in the downstream end of the plug from elevation 223 feet up. This was to allow easy installation of the remain- der of the conduits and the spherical valves. Under the specifications, the plug was to be 2'X-sack 6-inch maximum size aggregate concrete. The contractor proposed to pumpcrete the placement, which would require 4'/2-sack I'/j-inch concrete. This was approved with the requirement that the concrete be cooled to keep temperature rise equal to or less than that which would have been encountered using the mass concrete. To accomplish this stipulation, the contractor in- stalled 1-inch-diameter, thin-wall, steel tubing in all but the top lift of the plug which had been specified to be pumped. The tubing was on 3y2-foot centers and circulated cold water from a cooling plant at the downstream portal. The cooling was discontinued after 14 days on each lift. Equalizing Tunnel The 8-foot-diameter pressure-equalizing tunnel connecting the two diversion tailrace tunnels (Figure 68) was excavated and concreted in conjunction with construction of Diversion Tunnel No. 2. In the vertical portion of the tunnel, stopper and jacklog drills were used exclusively, working from a temporary platform. Fifteen-foot rock bolts were installed around the perimeter of the collar before excavation started, and additional 10-foot rock bolts were installed within the raise following each succeeding blast. The installation of the rock bolts stabilized the area as no movement was noted. While the raise was being driven, the contractor decided to continue excavation up to the valve airsupply tunnel. The additional raise excavation at this time probably was faster and safer than sinking a shaft from the valve air-supply tunnel down to the equalizing raise. The horizontal portion of the tunnel was mucked out with a slusher bucket attached to an air-operated tugger. Support consisted of rib steel left over from Diversion Tunnel No. 1 placed on 4-foot centers. Valve Air-Supply Tunnel The 8-foot-diameter, valve, air-supply tunnel (Figure 68) begins approximately 158 feet downstream from the equalizing tunnel, rises vertically 30 feet, then parallels the main tunnel until intersecting with the extension of the equalizing tunnel rise. Excavation and equipment used were essentially the same as used for the equalizing tunnel. River Outlet Works Between April and November 1967, the valve chamber was completed and the river outlet works was The remaining portions of the conduits, two 72-inch spherical valves, and two 54-inch hollow-cone valves connected to the conduits through the concrete plug in Diversion Tunnel No. 2 were installed the previous summer and fall. The outlet works was put into service November 15, 1967, on the day following the closure of Diversion Tunnel No. 1. installed. Figure 117. Wedge Seat Removal in Diversion Tunnels 131 The operating center for the river outlet is the Stacontrol cabinet within the river outlet control chamber. The 480-volt 3-phase pov/er was provided to the cabinet by the Oroviile Powerplant completion contractor. From this cabinet, lighting circuits were provided for the grout gallery, emergency exit tunnel, river outlet control chamber, river outlet access tunnel, and river outlet valve chamber. Power also was provided for the 220-volt, single-phase, sphericalvalve-pit, sump pump. Power, control, and position indicator lamps for the fixed-cone dispersion valve operators were provided. Station 2 cabinets for local control of the spherical valves were mounted in the tion 1 valve chamber. River Outlet Access Tunnel Convergence of the valve air-supply tunnel, equalizing tunnel, valve chamber enlargement, and the river outlet access tunnel in the same immediate area (Figure 68) presented a delicate excavation situation. Overbreak was experienced in the river outlet access tunnel collar, and many IS-foot-long rock bolts were installed along with wire fabric. The lower portion of the access tunnel was horizontal, and several 10-foot rock bolts were installed to stabilize this portion immediately behind the collar. The remaining 90% of the tunnel was inclined approximately 35 degrees and was excavated essentially the same as the other small tunnels. It was necessary to build a working platform from which to drill due to the steep slope. No structural steel was Emergency used. Exit Tunnel Portal excavation on the 8-foot-diameter emergency exit tunnel (Figure 68) was started May 14, 1964, after Oroviile Dam grout gallery excavation essentially was completed beyond the portal location. Crown bars (No. 18 rebars) were installed on 12-inch centers and grouted to stabilize blocky, slightly iron-stained, fresh rock at the opening. Nine W4X 13 steel ribs were in- In 1966, the Oroviile Dam Consulting Board expressed two concerns about the closure of Diversion Tunnel No. 1, which started on November 14, 1967. The first was a concern that after the first bulkhead gate was positioned, the force of the flowing water might be too great for the second gate to seat completely. The second concern involved a question of whether the bulkhead gates were sufficiently strong in the event of rapid filling of the reservoir ly after closure. The planned delayed by several factors to the start of the normal storm season. Measures, including the addition of the stoplogs and the concrete plug behind the steel bulk- head discussed later, were added to the closure sequence to assure its success. For the seating of the gates, concrete stoplogs (Figure 118) were placed across each opening during closure. By producing quiet water at the bulkhead gate, a diver was able to clean the slots so that the gate could be lowered without the pressure of running water. (By prior arrangement with upstream dam owners, the riverflow was held to less than 1,000 cfs.) After the first bulkhead gate was dropped into place, the stoplogs were removed from that side, moved to the other side, and the procedure was repeated. There was a substantial amount of leakage around both gates after they were dropped into place. The contractor succeeded in sealing the right gate by pumping a 1:1 mix of bentonite and Silvacel followed by fine sand into the edges of the gate. This was ineffective on the left gate. A section of 2-inch hose wedged between the slot and the gate on the left side succeeded in diverting the flow to the invert where it could be picked up in a drain. After the water was controlled, work began on the building of the form for the 30-foot-long upstream on 4-foot centers in the portal area. Jacklegs were used to drill all holes, and an overshot mucker and shuttle car were used for removing shot rock. Five 8-foot-long rock bolts were installed on 4-foot centers stalled in the arch throughout the 575 feet of tunnel. Numerous seams crossed the tunnel but did not create any problem. Closure Sequence By the fall of 1967, the river outlet in Diversion Tunnel No. 2, the connections between Diversion Tunnel No. 2 and the Powerplant, and the other tunnels were complete. Connections to Diversion Tunnel No. had bulkheads so that releases could be made through the river outlet while Diversion Tunnel No. 1 was being converted to its tailrace mode. The main dam and saddle dams were topped out, the spillway was nearly completed, and the reservoir was cleared. Tunnel No. remained to be plugged and converted 1 1 to a tailrace (Figure 68). 132 immediatehad been earlier closure Figure 118. Lowering Stoplogs plug to buttress the bulkhead gates. A 35-foot-diameter wood form was constructed adjacent to the trailing edge of the divider in the intake structure of the tunnel. The steel bulkhead gates served as the upstream form. The placing operation was continuous except minor breakdowns of equipment and for downs a few shut- to allow the air to clear in the tunnel. No at- tempt was made to completely seal off the top lift of the plug as its only function was to provide safe working conditions in the tunnel while the permanent plug was being constructed. As soon as the upstream plug was completed, the contractor moved to the permanent plug near the midpoint of the tunnel. The wedge seats were removed in the manner used in Diversion Tunnel No. 2, and an 18-inch drain pipe was installed in the invert of the The permanent plug then was constructed in Cooling pipes were installed in an identical method to Diversion Tunnel No. 2. tunnel. five 7-foot lifts. Prior to placing the last lift, the contact grout system was installed. A multiple header hookup was used on both pressure lines of the system with a return line connected to the vent pipe at the crown. The 18-inch drain pipe installed in the plug at the invert was backfilled by placing a 90-foot piece of 10inch thin-wall pipe inside the drain line and supporting it off the invert on chairs. Concrete was pumped through the thin wall into the drain pipe and forced to the upstream end. Pumping continued, forcing the concrete to reverse direction and flow back over the thin wall and out the downstream end of the drain pipe. The 10-inch line was cut and left in place. While the tunnel plug was being completed, drain holes were drilled in the downstream half of the tunnel and, as soon as the tunnel plug was completed, the plugs connecting to the draft-tube and pressure-equalizing tunnels were removed. All work in Diversion was completed on March 15, 1968. The steel bulkheads on the draft tube-tunnel No. 2 connections were removed from the floor of the tunnel shortly thereafter. Downstream demands were met by releasing water stored in the Thermalito facili- Tunnel No. 1 ties. Spillway Clearing. Appro.ximately way and chute and 1 1 5 acres, 40 in the spill- emergency spillway area, were cleared of brush and trees. The area below the emergency spillway was not cleared. 75 in the Excavation. The three major methods used to excavate the spillway were as follows: bottom-loading scrapers and pushcats, a loader with cats feeding the and bottom-dump wagons hauling the material, and two large shovels. In general, the scrapers were used to strip the area to rock. The shovels were used to excavate the rock after it was drilled and shot. The loader was used similarly to the scraper operation, the main difference being that it was possible to work this operation in belt rougher terrain as up to eight dozers were used to push material to the feeding hopper. A road was graded out below the hopper and the bottom-dump wagons could drive under the hopper to load. All drilling for blasting was done by percussiontype drills mounted on tracks and powered by air. The patterns varied greatly from area to area. The most generally used pattern was 8 by 8 feet; however, patterns ranging all the way from 2'/2 by 2/4 feet to 15 by 1 5 feet were used depending on the area, type of rock, and excavation objective. Excavation near structure lines had to be controlled to avoid damage to the rock to be left in place, and 840,000 tons of riprap for Oroville Dam had to be produced. In part of the emergency spillway, an additional 10 feet of excavation was required to reach acceptable foundation rock, resulting in considerable additional time for excavation and placement of the backfill concrete to subgrade. Approximately 90% of the chute foundation required blasting to reach grade. The only extra excavation directed was removal of a few clay seams in the foundation and a few areas where slope failures occurred. The depth of overburden in the approach channel was deeper than estimated and the slopes had to be changed from '^-A to I'/i-.l to prevent sloughing as the excavation reached the final grade. The slopes in the flood control outlet gate section proved to be of a lower quality rock than anticipated. There were several large seams running parallel with the chute. The planned anchor bars were replaced with grouted rock bolts, pigtail anchors, and chainlink surface covering in that area. Drain System. The foundation drains designed holes for the spillway included nearly vertical drilled 65 feet into the foundation rock of NX headworks Monoliths 25 and 26 and extensive perforated pipe systems on the foundation surface under the headworks, chute, and higher portions of the emergency spillway weir. Much of the drain system on the foundation surface was modified during construction. The original 4-inch-diameter, horizontal, pipe drains under the chute were redesigned in accordance with a recommendation from the Oroville Dam Consulting Board. The pipes were placed on a herringbone pattern to give them a downward slope and enlarged to a 6-inch diameter. The longitudinal collector system was enlarged proportionally and modified slightly. The effect of these modifications was to increase the system's capacity and its self-cleaning ability. The pipes remained on the foundation enveloped in gravel which projected into the reinforced-concrete floor of the chute. Similar drain pipes were impractical to place on rock surfaces under the headworks and emergency spillway weir. The contractor was allowed to substitute wooden formed drains of equal crossirregular 133 These forms were cut to fit the irregurock surface and remained in place after the concrete was placed over them. sectional area. lar Concrete placement started on January Mass concrete was placed monolithically in all monoliths (other than 25 and 26, which contain the gates) between the transition section at Station 18 - - 30 on the emergency spillway and the east end of the flood control outlet at dam Station 20-1-61.66. Mass concrete also was placed in the emergency spillway Concrete. 26, 1966. weir to the west of the transition. An on-site plant discharged into 4-cubic-yard concrete buckets positioned on low-boy trucks which hauled to the placing area where the concrete was handled and placed using a track-mounted crane. Six-inch vibrators were used to consolidate concrete. Concrete was placed in the monoliths in lifts of 7 feet - 6 inches. Wooden starter forms were used until 7-foot - 6-inch, cantilever, steel forms could be used. An adjustable steel form was used to form the curved or ogee section of Monoliths 1 through 20. The uppermost lift of the ogee section was formed using wooden forms. Seven screed ribs were shaped to the desired curve, between which panels were added as concrete was placed. When the concrete would hold its shape, the forms were removed and the surface finished. Structural concrete was placed in Monoliths 25 and 26 of the flood control outlet, the approach walls, the chute walls and invert, and the terminal structure. Flood control outlet concrete was placed by a trackmounted crane. When the concrete reached an elevation that could not be reached by the crane, a conveyor-belt system was used. This conveyor system was used mainly in the Monolith 26 half of the flood control outlet. The conveyor-belt system was used less in Monolith 25 due to a more accessible area for a crane to be positioned at Monolith 24. Concrete placing for the spillway chute invert began on September 8, 1966. A conveyor-belt system was used to transport the concrete from the chute banks to point of placement. Concrete was transported from batching plant to a conveyor reclaim hopper by "bathtub" trucks. A 40-foot, steel-beam, slip form was used to screed the concrete to invert grade. This slip form, along with the discharge portion of the conveyor, rode on steel rails positioned along each side of the chute slab being placed. The slip form was propelled by the use of a winch geared to keep pace with the placing of concrete. This slip form was used chiefly on the steeper area of the chute. A smaller slip form was used to screed concrete for the chute wall footings. Chute invert concrete in the area of lesser slope near the flood control outlet was placed by a truck-mounted crane and concrete bucket. Terminal structure concrete of the chute also was placed in this manner. Rigid wood forms were constructed to contain the concrete in the chute walls. Windows were cut in the backs of the wall forms through which concrete was vibrated until it reached that level. A truck-mounted crane and concrete bucket were used to place the concrete in forms. A leveling platform was made from timbers to position the crane while working on the steep portion of the chute invert. The total volume of concrete placed was 165,000 cubic yards. Lists were made of all elecconduits and equipment to be installed prior to placing each lift of concrete. The lists were reviewed whenever necessary to ensure the installation of conduits in their proper places. The ground cable was completed as concrete was placed. All electrical conduits were in place before the electricians started cleaning the conduits and blowing lines into them for use in pulling the conductors through the conduits. The standby generator was placed in the control room. After it was started and checked, it was used to operate the hoists because the temporary source of Electrical Installation. trical power had been removed. As the radial gates were installed, temporary circuits were run to the hoist motors so the hoists could be operated and the gates checked before the controls were activated. Installations. The concrete was blocked out of the piers in the immediate vicinity of the trunnion beams. The trunnion beam was placed over the tensioning tendons and set to final alignment. The bearing plates then were brought into contact with the beams. When the trunnion beams and the bearing plates were positioned, concrete was placed in the blocked-out areas. After the concrete had achieved its design strength, the rods were tensioned to design loading and no rod failures occurred. After the tendons were tensioned, the voids between the rods and the sleeves were grouted. The side-seal plates were aligned by swinging an arc with a chain from the centerpoint of the trunnion. After the plates were in proper position along the arc of the gate, the plates were adjusted parallel to the walls of the bay by transits. By the time the gates were to be placed, the radial wall plates were within '/z inch of their proper position. The contractor chose to erect the gates in the bays in their operating position. This method was used because there was not enough work space to bring the gate skins into the bay in one piece. Erection of the radial gates was done as follows: (1) two halves of the skin with the side seals attached were moved into place; (2) horizontal and vertical members were bolted to the skins; (3) canted-arms and trunnions were bolted in place; (4) the gate was leveled and aligned and the two halves welded together; and (5) the gate was lowered to its closed position and final adjustments made to position the gate and seals. Gate Grouting Program Foundation grouting for Oroville Dam consisted of curtain grouting a single row of holes the full length of the core trench and spillway crest, extending a max- 1!- 134 1, imum depth of 200 feet into rock; blanket grouting of the core trench and core block foundation; envelope grouting over Diversion Tunnels Nos. 1 and 2 and the Powerplant; and a minor amount of curtain grouting from the Palermo outlet works tunnel (Figure 66). Grout Curtain. The grout curtain for Oroville Dam is located approximately along the upstream oneon the abutments and the core block in the channel. This curtain was drilled and grouted from the grout gallery to where the gallery reached about elevation 750 feet, and from the rock surface between elevation 750 feet and the dam crest at elevation 922 feet. The dam and spillway curtains join on the upper right abutment at dam Station 21 + 29. The plane of the curtain dips 75 degrees upstream where grouted from the gallery section and is vertical where grouted from the rock surface. To control leakage and grout placement, the curtain was divided into three zones. Zone 1 extended 50 feet into rock and was drilled and grouted in a minimum of two stages with a maximum hole spacing of 10 feet. Grouting pressures of 50 to 100 pounds per square inch (psi) were used in the gallery; 25 to 50 psi from the rock surface. Zone 2 extended 100 feet below foundation elevai tion 500 feet; above elevation 500 feet, the depth equaled one-fourth the potential reservoir head and was drilled in one stage using packers with a maximum hole spacing of 20 feet. The normal grouting pressure was 150 psi. Zone 3 extended 200 feet below elevation 500 feet, one-half the potential head above elevation 500 feet, and was drilled in one stage using packers with a maximum hole spacing of 40 feet. The grouting pressure ranged from 200 to 300 psi. The total grout take was 23,763 cubic feet of cement and the average was 0.28 of a cubic foot per foot of third point of the core trench ' hole. i leakage. Final spacing of most holes upstream from the grout gallery ranged from 10 to 20 feet apart. In addition to grouting from the core trench surface ahead of embankment placement, 123 holes were connected to the gallery with pipes and grouted under an embankment cover of 100 feet to allow grouting at pressures of 50 to 100 psi and eliminate surface leakage. Most holes were inclined 40 to 70 degrees from horizontal and were aimed to cross steeply dipping joints and shears a few feet below the foundation surface. In general, holes ranged from 10 to 30 feet deep; a few holes were as deep as 70 feet. The total grout take was 13,745 cubic feet of cement and the average was 0.23 of a cubic foot per foot of hole. Envelope Grouting. A grout canopy, extending 700 feet downstream from the tunnel plug section, was constructed over both diversion tunnels and around the underground powerplant to reduce inflow into the plant and protect the concrete lining of the diversion tunnels from a potential reservoir pressure of 300 psi. The grout curtain for Oroville Dam extends from the grout gallery to the downstream end of the envelope to produce a continuous curtain above the powerplant area (Figure 69). Drilling and grouting were begun shortly after the top heading excavation was completed through the draft-tube section. All holes in each ring were drilled to the full depth of the first grouting zone as the drilling jumbo progressed downstream from ring No. 1. Grouting operations followed six to eight rings behind the drilling jumbo. Reservoir Clearing Clearing of the reservoir was planned to enhance recreational use. Vegetation was not removed in certain areas to be submerged to provide fishery enhancement. Public beach areas were grubbed of stumps and The plan also included an agreement with the Forest Service and State Division of Forestry for the prevention and suppression of fires during clearroots. U. Blanket Grouting. The blanket grouting program consisted of shallow low-pressure grouting of most of the core trench and core block foundation upstream ifrom the grout curtain. This sealed the many joints and shear zones that cross the foundation and also consolidated areas of strongly fractured or weathered rock. Most blanket grouting in the core block was j ,1 I J ',, : I done after concrete placement. Spacing and depth of blanket holes were governed [by the nature and extent of foundation defects en(Countered and by grouting results as the operation progressed. In areas of weathered or closely fractured foundation, final hole spacing was as close as 5 feet and holes were arranged more or less in an equilateral , , 1 i ; pattern. In areas of fresh sparsely fractured founda- such as portions of the core block and lower abutment core trench, holes were up to 40 feet apart. (The general practice was to space the initial holes tion, oi itli from 20 to 30 feet apart, then reduce the spacing if the initial holes took grout or if there was severe surface I S. ing. Elevation 640 feet was established as the lowest which the reservoir would be drawn down under extreme conditions. Clearing of the area below elevation 640 feet consisted of removal of all loose floatable material. This included drift along the streams, logs, windfall trees, and miscellaneous improvements. The area between elevations 640 and 900 feet, with the exception of areas of vegetation retention, was cleared of all trees, brush, and improvements. All stumps and roots were grubbed out of the 840 acres of planned beach areas. In the remaining 7,660 acres above elevation 640 feet, stumps 6 inches or less in height were allowed to remain. Approximately 1,100 acres of vegetation retention was provided above elevation 640 feet for the enhancement of the reservoir fishery. In these areas, all coniferous trees over 25 feet in height and deciduous trees over 60 feet in height were cut down and tied to their stage to 135 A total of nearly 7,000 trees over 12 inches in diameter were cut and anchored with '/^-inch galvanized wire rope, and a total of about 5,000 trees 12 inches or less in diameter were cut and anchored with '/-inch galvanized wire rope. The work of clearing timber and brush, between elevations 640 and 900 feet, was performed in three separate operations: (1) cutting timber and brush, (2) raking and piling cut material for burning, and (3) burning and final cleanup. Cutting of timber and brush was performed with dozer equipment and chain saws. The method of cutting timber and brush was dependent upon roughness of terrain and access. Dozers equipped with sharp cutter blades, set at an angle, were used for cutting timber and brush on flat and moderately steep terrain. On steep terrain, a second dozer with a heavy-duty winch cable was used to control the downhill movement of a dozer with a cutter blade and to haul it back up the slope. This operation of using two dozers on steep terrain is known as a "yo-yo" method of cutting and stripping hillsides. Chain saws were used for cutting in areas not accessible to dozer equipment or for cutting large trees in heavily timbered areas. The work of raking and piling cut timber and brush was performed by hand labor and by dozers equipped with brush rakes or regular dozer blades. On steep terrain, a "yo-yo" method was used to pile material in windrows. In areas not accessible to heavy equipment, chain saws were used to fell the timber and cut materistumps with wire rope. al into shorter lengths to facilitate hand piling and burning. Dozers and labor crews were used to collect and push together unburned chunks until completely burned. Burning was restricted to the winter months or as permitted by the Division of Forestry. The work of raking and piling was contingent upon availability of equipment, manpower, terrain, and accessibility. At certain locations, the interval of time between cutting, piling, and burning actually spanned a period of six months or more, which allowed the cut timber to dry and brush to cover the ground during the late summer months. To prevent the spread of wild fires, and before piling and burning in these areas were permitted, the contractor was required to provide adequate fire breaks near the uncut timber and brush lines at elevation 900 feet. Work of grubbing areas for recreation was performed after all clearing was completed. Grubbing was performed by dozers equipped with regulation dozer blades and with a single ripper tooth clamped and mounted on the left end of the dozer blade. The ripper tooth was mounted at one end of the blade so that stumps being rooted out would be visible to the operator. The contractor cleared approximately 12 dwellings located at Bidwell Bar, Bidwell Bar Canyon, and Enterprise and disposed of them by burning. The Department removed all buildings located 136 along the Western Pacific Railroad and buildings located at Bidwell Bar. These buildings were burned in 1964 prior to the reservoir clearing contract. Saddle Dams Construction of the Saddle December Dams commenced in The contract specifications allowed 275 days to complete the work on both dams. Completion was timed to precede closing of the second diversion tunnel at Oroville Dam and commencing of storage in Lake Oroville. The planned date for completion of Oroville Dam and start of storage in the reservoir was October 17, 1967. The actual start was 1966. on November 14, 1967. Foundation. All foundation excavation at both dams was done by common means, using scrapers and dozers with rippers. Excavation was started January 10, 1967 and essentially was completed on February 28, 1967. The Bidwell Canyon Saddle Dam foundation outexpose strongly or moderately weathered rock. The cutoff trench was excavated to fresh rock or firm moderately weathered rock. The bottom of the trench was cleaned of loose materials with hand tools and air jets. The downstream Zone 3 foundation within Miners Ranch Reservoir was not dewatered during embankment construction. It had been determined by probing, prior to construction of the Saddle Dam, that this area consisted of strongly weathered rock which was stripped of topsoil during construction of Miners side the cutoff trench was stripped to Ranch Dike. Ground water issued from the spoil pile adjacent to the upstream left abutment of the main dam during foundation excavation. Water also flowed from the toe of the Miners Ranch Dike. These flows were drained from the foundation area by placing a French drain of coarse rock at the base of Zone 3 and by digging a drainage trench through the spoil pile north of the Dam. Excavation for Parish Camp Saddle Dam foundation outside the cutoff trench exposed strongly and moderately weathered phyllite over most of the area. The cutoff trench was excavated to fresh or firm mod- erately weathered phyllite. The grout curtain for both dams was 25 feet deep in Holes were inclined 20 degrees off vertical along the plane in order to cross the nearly vertical cleavage and schistosity. The ends of the curtain extended to foundation elevation 917 feet on all abutments. Stage grouting was used where necessary. In the more weathered areas where excessive amounts of grout might have leaked to the surface, a 10-footdeep upper stage was drilled and grouted at 10 psi before drilling and grouting the remaining 15 feet of hole. In fresher rock, it was possible to grout the entire hole with a single hookup at a pressure of 25 psi without surface leakage. a vertical plane. Construction Materials. Impervious borrow for Bidwell Canyon Saddle Dam was obtained by strij> ping near-surface, strongly weathered, decomposed amphibolite. Initially, material was taken from the two designated borrow areas north of the west dam. When these sources were depleted, one of the areas was extended farther northward and a new borrow area was opened near the east end of the main dam. These new sources were explored with bulldozer trenches excavated by the contractor at the direction of the Department. To help alleviate the shortage of impervious borrow, the design of the west dam was modified to reduce the quantity of impervious material required in the embankment. This modification permitted the use of more rocky material in the outer of the west dam impervious section. Such material could be obtained by excavating deeper in the designated borrow areas. Pervious borrow initially came from the designated source, a rock spoil pile adjacent to the main dam made up of material from portal excavation of tunnels leading in and out of Miners Ranch Reservoir. When this stockpile was nearly depleted, a few thousand cubic yards of rock was hauled from a spoil pile of rock wasted during construction of the Oroville-Quincy Road relocation near Bidwell Bar Bridge. This source limits aii IWi letd low linen y piol) It ill hwt {ion •m \m kn niu oitk bdi ijyll leiM reesi •.id the lODi was abandoned when it was found to be more economical to rip and remove rock from one of the designated impervious borrow areas which had already been stripped of impervious material. Filter material. Zone 2B, was trucked into the area from the Feather River dredger tailings and was produced by mixing the necessary ingredients, utilizing a dragline and a dozer. The proportions of different materials had to be changed somewhat when mechanical analysis tests indicated an increase in that portion passing the No. 200 screen. This condition was controlled by frequent testing of the material at the source. Zone 4B is clean, coarse, dredger-tailing cobble. Impervious borrow for Parish Camp Saddle Dam was obtained from the weathered surface of the Calaveras phyllite, which was decomposed to gravelly clay and clay. The material came from excavation of the access road to the dam and from the designated borrow area just northwest of the dam. Pervious material was imported by the contractor. A small amount of riprap for Bidwell Canyon Saddle Dam was obtained from the designated pervious borrow source adjacent to the main dam by separating out the larger rock fragments using dozers equipped with rock rakes. Most of the riprap was imported by the contractor from a department-owned spoil pile at Thompson Flat north of Oroville which contained rock excavated from a deep cut during construction of the Western Pacific Railroad relocation. This riprap also was separated out with dozer-mounted rock rakes. All riprap placed on the dams was fresh, hard, and durable metamorphic rock. Mine Adit Plug. Work under the contract included placing compacted impervious embankment to cover the portal of an abandoned, collapsed, mine adit one-third mile northwest of Parish Camp Saddle Dam. This embankment was designed to prevent possible leakage from the reservoir. The contractor stripped the area around the adit portal with dozers and a backhoe. The portal was found to be completely collapsed and was not opened during excavation. Water flowing from the adit at about % of a gallon per minute was sealed off with placement of the compacted embankment. Construction of Embankment. Impervious ma(Zone IB, IP, and mine adit embankment) was excavated by scraper units which picked up both clay and weathered rock for placement. After placement, the lift was cut to a thickness that would produce a finished layer not more than 6 inches in depth by a grader and rolled by a 5-foot by S-foot, double, sheepsterial foot roller. Filter material (Zones 2B and 2P), after being placed in layers that resulted in a thickness of not more than 12 inches after compaction, was moistureconditioned to prevent bulking. Compaction was accomplished by four passes of a large tractor. Pervious material (Zones 3B and 3P) was placed and compacted in the same manner as Zones 2B and 2P. Care was taken to distribute the embankment material to produce a well-graded mass of rock with a minimum of voids. By agreement with Oroville-Wyandotte Irrigation Miners Ranch Reservoir was lowered as far as possible during Zone 4B placement. Underwater District, placement was accomplished by dumping, starting from the edge of the water and proceeding parallel to the longitudinal axis of the dam. This procedure was followed until the top of the material was 1 foot above the surface of the water. Thereafter, the material was placed in layers not to exceed 2 feet in thickness after compaction with a large tractor. Riprap was placed to its full thickness in one operation. Care was taken not to displace the adjacent material. Riprap was placed on the upstream faces of the embankment with front-end loaders but had to be straightened and rearranged with a truck crane and a clam bucket to produce a well-graded mass with a minimum of voids. 0* 137 BIBLIOGRAPHY Department of Public Works, "Report on Comparison of Oroville, Big Bend and Bidwell Bar Reservoir Development of Feather River", August 1949. California Department of Water Resources, "Basic Data Report on Test Fills of Proposed Embankment Materials for Oroville Dam", December 1961. Chadwick, W. L. and Leps, T. M., "Inspection and Review of Oroville-Thermalito Project Facilities, Oroville Thermalito Diversion Dam, Thermalito Forebay Dam, Thermalito Afterbay Dam, Feather River Hatchery California Sites for Dam", February 1973. Daehn, W. W., "Development and Installation of Piezometers for the Fluid Measurement of Pore-Fluid Pressures in Earth Dams", ASTM, 1962. Golz6, Alfred R., "Oroville Dam", Western Construction Magazine, April 1962. Golz6, A. R., Seed, H. B., and Gordon, B. B., "Earthquake Resistant Design of Oroville Dam", Proceedings of ICOLD, 1967. Gordon, B. B., Hammond, W. D., and Miller, R. K., "Effect of Rock Content on Compaction Characteristics of Clayey Gravel", ASTM, STP 377, June 1964. Gordon, B. B. and Miller, R. K., "Control of Earth and Rockfill for Oroville Dam", ASCE Journal of the Soil Mechanics and Foundation Division, May 1966. Gordon, B. B. and Wulff, J. G., "Design and Methods of Construction, Oroville Dam", Edinburgh, Scotland, Communication, 8th Congress on Large Dams, 1964. Hall, E. B. and Gordon, B. B., "Triaxial Testing Utilizing Large Scale, High Pressure Equipment", ASTM, Special Tech. Pub. 361, 1963. Kruse, G. H., "Instruments and Apparatus for Soil and Rock Mechanics", ASTM-392, pp. 131-142, December 1965. Kulhawy, F. H. and Duncan, J. M., "Stresses and Movements Mechanics and Foundation Division, July 1972. Lanning, C. C, "Oroville Dam Diversion Tunnels", ASCE in Oroville Dam", ASCE Journal of the Soil Journal of the Power Division, October 1967. Marachi, N. D., Chan, C. K., and Seed, H. B., "Evaluation of Rockfill Materials", Mechanics and Foundation Division, January 1972. O'Neill, A. L. and Nutting, R. G., "Material Exploration for Oroville Society for Testing Materials, June 1963. ASCE Journal of the Soil Dam", 66th Annual Meeting, American Schulz, W. G., Thayer, D. P., and Doody, J. J., "Oroville Dam and Appurtenant Features", Journal of the Division, American Society of Civil Engineers, Volume 87, No. 902, July 1961. Stroppini, E. W., Babbitt, D. H., and Struckmeyer, H. E., "Foundation Treatment for Embankment Rock", ASCE Journal of the Soil Mechanics and Foundation Division, October 1972. Power Dams on Thayer, D. P., "Oroville Test Fill Experience in Compacting Granular Material", Proceedings 7th Congress on Large Dams, Volume IV. P., Gordon, B. B., and Stroppini, E. W., "Soil Mechanics Aspects of Oroville of Civil Engineers, Water Resources Engineering Conference, May 1963. Thayer, D. Thayer, D. August P. and Stroppini, E. W., "Hydraulic Design for Oroville Spillway", Dam", American ASCE Society Hydraulic Conference, 1965. Adams, R. Concrete, ACI, 1963. Tuthill, L. W., F., and Mitchell, D. R., "Mass Concrete for Oroville Dam", SP-6 Symposium on Mass United States Bureau of Reclamation, "Hydraulic Model Studies of the Diversion Tunnels for Oroville Dam", Hydraulics Branch Report No. HYD-502, January 18, 1963. "Hydraulics Model Studies of the Flood Control Outlet and Spillway for Oroville Dam", Hydraulics Branch Report No. HYD-510, September 30, 1965. "Hydraulic Model Studies of the River Outlet Works at Oroville Dam", Hydraulics Branch Report No. HYD-508, October 11, 1963. Western Construction Magazine, "Big Show Starting at Oroville Dam", May 1963. Wilber, A. F., and Mims, J. R., "Construction Procedure at Oroville Dam", ASCE Conference Paper, Denver, , .., Colorado, May 16-20, 1966. 139 SOUTH \gvowLLE 8? v0 000w?. GENERAL POWER CANAL THERMALITO DIVERSION OROVILLE-CHICO ROAD BRIDGE DAM CHEROKEE I EDWARD HYA rr/A? POWERPLANT z? OPERAYION AND MAINTENANCE CENTER 0 I 140 Figure Location Map?Thovmolifo Diversion Darn CHAPTER VI. THERMALITO DIVERSION DAM General Description and Location Thermalito Diversion Dam is located on the Feather River approximately '/ of a mile upstream from the Oroville-Chico highway truss bridge and 4'/2 miles downstream from Oroville Dam. The nearest major road, State Highway 70, crosses the Feather River about 2 miles downstream of the Dam (Figure 119). Thermalito Diversion Dam (Figure 120) consists of a 62S-foot-long, concrete, gravity section with an ogee spillway; a canal-regulating headworks structure; and an earth embankment section at the right of the canal headworks (Figure 121). Figure 120. Aerial View Purpose Thermalito Diversion Dam diverts water into Thermalito Power Canal for power generation at Thermalito Powerplant and creates a tailwater pool for Oroville Powerplant. The impounded reservoir acts as a forebay when Edward Hyatt Powerplant is pumping water back into Lake Oroville. The reservoir also is used for incidental recreation. Chronology The concept of Thermalito Diversion Dam evolved when a canal to a powerplant and offstream afterbay was first proposed. The Diversion Dam site formerly was considered for an afterbay. The pumpin 1956 storage concept required more afterbay storage than was available at the Diversion Dam. Detailed design —Thermalito Diversion Dam 141 142 7 m- I ?25? ll!? (AMMVH pot-OPIFDI I derail?? EH ?v if" u: 00?0 il - to" Figure 121. -4-1 Q. 3 0?4? General Plan and Pro?le of Darn 5 -1 114' l?wl? a 4w?? arc/7-11- . 4 . N/mlde/I?t' wwaXN 15m Jam5/0 110? .m at/ nor/u rum-M. (mm, m? uh." our ant puma. Mp, - mou- 0 ?If! 3 :m?m Im- that When (sum/sf when Im a [J'w -. AA A . - 2?00 15'; 5'5 In 7?57 l0' 11:00 M'w gull l'l 50' .. "nu-v.1 1.- u?um mun amne- OIVEISIOI I?ll RM no {Liuno? Amm?mon No .mm A: um 9-1er Mim? I??l?qtwork was initiated in 1961, and work on the Diversion Dam was started in October 1963 and completed in March 1968. A statistical summary of Thermalito Diversion Dam is shown in Table 10. Regional Geology and Seismicity The Dam site is approximately 4 miles west of Oroville Dam, and the section on regional geology and seismicity contained in Chapter V of this volume applies to the Diversion Dam as well as to Oroville Dam. shear zones were found in the foundation. Inspection of the foundation rock, surmapping, and core hole logs indicated that foundation strength would not be a critical factor in the stability of a dam of this height. Therefore, no strength testing of the rock was performed. Grouting was necessary to consolidate the foundation and miniStrength. face geologic mize seepage. Overpour Section Description. The spillway consists of a concrete, overpour section with a crest across the channel of the Feather River. An energy dissipator is pro- gravity, Design Foundation Geology. Rocks of the Jurassic Oregon City formation comprise the foundation of the Diversion Dam. This formation is composed of a sequence of metamorphosed volcanic and sedimentary rocks. Two rock types were exposed in the dam foundation: metaandesite, which is a massive, fine-grained, equiangular rock; and metaconglomerate, which contains Site volcanic cobbles in a medium- to coarse-grained ground mass. Both rock types are extremely hard, dense, and durable where fresh. Shear zones and welldeveloped joints cut the rock at various angles, creating a blocky or slabby appearance; however, no major TABLE 10. Statistical Summary vided at the toe of the spillway to prevent scouring of the channel and possible undermining of the Dam. Hydrology. Spillway capacity of 320,000 cubic second (cfs) was determined from a study of the economics, operational requirements, and physical limitations of the site. This capacity is in excess of feet per the controlled releases for the standard project flood from Oroville Reservoir (150,000 cfs). Discharges in excess of 320,000 cfs will not overtop the abutments of the nonoverpour sections but will flow over the spillway bridge above the gates; however, no major damage will occur with discharges up to the peak spillway discharge of 650,000 cfs at Oroville Dam. The Ther- of Thermalito Diversion Dam THERMALITO DIVERSION DAM SPILLWAY Type: Gated ogee crest with slotted-bucket energy dissipator radial gates 40 feet wide by 23 feet high Type: Concrete gravity 233 feet 24 feet 1,300 feet Crest elevation Crest width Crest length Streambed elevation at dam Lowest foundation elevation axis Top 226 feet Ogee 205 feet 560 feet elevation of gates crest elevation. Crest length 105 feet 90 feet Maximum probable flood inflow Peak routed outflow Structural height above foundation Volume of concrete 143 feet 154,000 cubic yards Freeboard above spillway crest Freeboard, maximum Maximum surface elevation 8 feet INLET-OUTLET THERMALITO DIVERSION POOL Dead pool storage Maximum operating surface elevation Minimum operating surface elevation.. Dead pool surface elevation Shoreline, maximum operating elevation Surface area, maximum operating elevation.. Surface area, minimum operating elevation.. 650,000 cubic feet per second 650,000 cubic feet per second 246 feet 28 feet operating surface Maximum operating storage Minimum operating storage — 14 13,328 acre-feet 12,090 acre-feet 5,849 acre-feet 225 feet 221 feet 197.5 feet 10 miles 323 acres 308 acres Edward Hyatt Powerplant Maximum generating release Pumping capacity 16,900 cubic feet per second 5,610 cubic feet per second Thermalito Power Canal Maximum generating flow Maximum pumping flow 16,900 cubic feet per second 9,000 cubic feet per second OUTLET WORKS Oroville Fish Hatchery: 60-inch reinforced-concrete pipe with 60-inch slide gate shutoff on upstream side of dam flow regulation at hatchery 100 cubic feet per second Capacity To — — River Release: 60-inch reinforced-concrete pipe control, 42-inch fixed-cone dispersion valve guard valve, 60-inch slide gate on upstream side of dam 400 cubic feet per second Capacity — 143 malito Diversion on Figure Dam spillway rating curve is shown Structural Design. 123, Sections D The spillway section (Figure and E) was constructed of mass con- crete with a 2-foot-thick surface of high-strength concrete on the spillway face. The vertical upstream face recessed 6 feet downstream from the dam axis to reduce the volume of concrete required. The 25-foot-radius, slotted-bucket, energy dissipator was designed to withstand the forces resulting from falling water during an occurrence of the design is flood as well as to resist the tailwater loading. Uplift forces are resisted by the weight of the concrete bucket. Waterstops were placed at contraction joints prevent the buildup of excessive uplift forces during spillway operation. Concrete gravity retaining walls at both ends of the energy dissipator contain the turbulent flow of the slotted bucket and prevent scouring of the abutments. to Thirteen 5-foot-thick piers and two 3-foot-thick training walls support the radial gate trunnion anchorage assemblies. The piers also support the bridge over the spillway section and will accommodate stop- The spillway bridge, at elevation 233 feet, was designed to provide access across the Dam, serve as the hoist platform for the radial gates, support maintenance equipment, and allow placement of stoplogs. Removable railings were placed along the curb on the upstream side of the bridge to provide access to the stoplogs. Permanent railings are located on the downstream side of the bridge. logs. Spillway Gates and Hoists Each of the 14 radial gates on the spillway crest consists of a curved skinplate welded to vertical ribs which in turn are welded to two horizontal girders. The loads are transmitted by radial arms which are bolted to the horizontal girders and to the trunnion assembly. The load from the gates is transmitted into the piers by prestressed anchorage assemblies. The 14 hoists are electric motor-operated, conventional, wirerope type designed for 90 kips, with the load equally divided between the four wire ropes. The hoists can be controlled either on-site, at the local control building, or from the Oroville Area Control Center. Stability were performed on all sections of under various conditions of loading. The monoliths are not keyed together, and no provisions were made for bonding the vertical joints. Waterstops are provided to prevent leakage through Stability analyses the Dam these joints. Curtain grouting was done through a grout gallery Dam. Spacing and depth of the holes are de- in the scribed in the construction section of this chapter. Although foundation drainage is provided, it was assumed, for conservative design purposes, that the drains would remain inoperative. 144 Water and pressure profiles over the spillway were and the loads resulting from the static and dynamic pressures on the crest, headwater, and tailwater and from velocity were incorporated into the calculated, 122. stability analyses. No "over-turning factor" as such a sliding factor (ratio of was determined; however, was calculated for the critical section. Due to the extremely uneven surface of the foundation, it was believed that sliding could not occur and, therefore, more emphasis was placed on the shear friction factor. Another factor which would resist sliding but was disregarded in the analysis was the bearing provided by placing the downstream toe of the Dam directly against the slope of the excavation. It was assumed that earthquakes would not occur simultaneously with riverflows in excess of 150,(X)0 cfs. Increases in stress due to a horizontal seismic acceleration factor of O.lg were small and did not govern vertical to horizontal forces) of 0.87 J I design in any case. Nonoverpour Sections A ! nonoverpour concrete section (Figure 123, Sec- tion F) with a 24-foot-wide crest at elevation 233 feet adjoins each side of the spillway section. The design and stability analyses were the same as for the overpour section. The crest accommodates vehicles and is provided with curbs and railings similar to the spillway bridge. Three 60-inch-diameter outlets equipped with electrically operated slide gates are provided in the abutments. The one in the right abutment provides a water supply outlet for the Feather River Fish Hatchery of 100 cfs. The other two are in the left abutment: one providing for a minimum river release of 400 cfs, and the other for a possible future water demand. A 42inch-diameter fixed-cone dispersion valve with an electric motor operator is located in a valve vault just downstream of the left abutment. It is used to make The valve discharge impinges onto the spillway apron parallel to the dam axis. Since the head and flow are constant, except for short periods, only on-site control was provided. river releases. Thermalito Canal Headworks Due to the extemely high value of head for power generation, it was imperative to minimize head loss. This was accomplished by increasing the velocity of the water at a constant rate through the approach channel. Warped transitions were adopted both upstream and downstream from the headworks structure (Figure 121). This was done to minimize head loss through the structure and thus better meet pumpstorage requirements. Sizing was based on a capacity of 16,900 cfs. Piers were designed to support the gates, bridge, breastwall, and hoist platform and resist the resultant forces due to their respective critical loading conditions (Figure 124). Under normal loading conditions, 230 a IN Figure 122. Spillway Rating Curve /DISCHARGE 145 S I hi 8 '^'^ -V Kit I7 i *»j.<.rl' I! u • I I* Figure 123. 146 Spillway Sections 147 [-Cnna/ out.441" Humor .cryp/p NW5 1250 /Duo.l ?yaw-41 A 24~49; -A .4 (inn 3! 3 143/? . . - A: any". .- .JETAJL r535T Flguro 124. Power Canal Headworks?Plan, Pro?lo, and Smlom AF 562 (Ni/Id I 4 4 4. srcr/ozv r-r A s'ev 1rd ., 6 I I o-ouut unusua- nun-Auto mvusnou on: MS RN men-41mm cum. neaowonxs kn}, I PLAN, (LEVAYION, stcno[Lia/4714?] 4% seismic acceleration was included in the design. Piers are 5 feet thick with vertical and horizontal reinforcing steel in both faces. Prestressed tendons are embedded to provide anchorage for the gates. The left side of the headworks structure is flush with the face of Monolith 1 (Figure 121, Section A). A 4-foot-thick wall at the downstream face of the monolith connects the Dam to the left counterfort wall. The breastwall is formed by three reinforcedconcrete vertical walls, simply supported between piers and endwalls (Figure 124, Section A). The purpose of the breastwall is to protect Thermalito Power Canal from high floodflows. A bridge across the headworks structure provides access to the Dam and left bank of the Canal. It consists of a reinforced-concrete slab, continuous between the piers and walls. A platform, simply supported between the piers and walls, is situated at the top of the breastwall and is used to support gate hoist equipment. Live loads used for design included 100 kips for the gate, 25 kips for the hoist, 2.5 kips for the motor, and 25% of the gate weight for impact. Radial Gates and Hoists. The three gates are of similar design to the spillway gates. The gate hoists are identical to the spillway gate hoists except for the spacing of the wire ropes. These gates were designed to be used either fully open or fully closed. The base of the canal headworks structure extends to sound rock of the same quality as the foundation of the Dam. Hydrostatic pressure is relieved by the placement of weepholes in the upstream transition walls and by underdrains emptying into the River on the downstream side of the struc- Foundation. ture. Stability Analysis. Stability of the headworks structure was investigated with criteria similar to the Dam. Foundation conditions were considered compa- rable to the Dam. Grouting was performed directly from the surface and similar foundation drainage was provided. Embankment Section Description. The embankment section (Figure 123, Section J) of the Dam between the Canal and the right abutment provides freeboard only. The downstream toe is at elevation 228 feet, 3 feet above normal water surface of the Power Canal, and the crest is at elevation 246 feet. In addition to riprap for protection from wave action, a 4-foot concrete parapet with a top elevation of 250 feet is situated on the upstream side of the crest of the embankment. The crest serves as an access road to the hoist platform of the canal headworks. Construction Materials. Pervious material for the excavation and supplemented with dredger tailings from downstream borrow areas that were designated for use in construction of Oroville Dam. Impervious material was obtained from abutment stripping. embankment was obtained from foundation Stability Analysis. Stability of embankment sec- was determined by the Swedish Slip Circle method of analysis, assuming reservoir-level criteria similar to that assumed for the gravity dam. A seismic acceleration factor of O.lg was incorporated into the tions design forces. fall below 1.1 The slope stability safety factor did not most adverse condition analyzed. for the Construction Contract Administration General information for the major contracts for the construction of Thermalito Diversion Dam is shown in Table 11. Thermalito Diversion Dam and its appurtenances were constructed as part of the Oroville Dam contract (Specification No. 62-05). Associated mechanical and electrical equipment was furnished under separate contracts. "mm - nan-an. mo OIU l- p; 151,-! :as an n-m-z ll "Pin-"1 lvu?. 4; Elant-m: u. -m~u ?my o-muu' . Wily?, ~uw pram; mo. in: D14 0. p4 y-4 no: paw/w: :0 7- .Iv.v- In 9; to: pun-u :2 ?v Imuvnv :00 i. u? nu a WlInn'uw ?guru/ID?! via: my; I u- v. 57 3505? 905d nun?nauaopu-nwv? any a nun-un- rw-n/rw but on ban- M- gnaw 7 r? on. 1r ?4 p. you bun-m av .Illira ?0/13? Um" a amu- nun-unnnevi: an? tuna?1711002 n- vm-w uu um." "mun- mic-1104? c- rr I Z: {gay 1 771;? . I (run HI) . 1 ruin/v Jil'a'x? ?nal/r?? hw?r' 7 7mm 3-7/5 . Figure 125. West Bank Diversion Plan the ill: zed had 149 dewatering pumps were placed into operation near the downstream end of the cofferdam to take care of seepage water. Figure 126. Channel Bypau (Aerial View) Closure. Third-stage diversion consisted of closing the 15-foot by 15-foot opening through Monolith 8, thus forcing the River to flow over the completed spillway structure. Sudden closure of the 15-foot by 15-foot opening would have been a construction advantage but, due to flow requirements downstream of the Dam, this procedure was not permissible. As a result, the bulkhead gate was lowered in increments allowing gradual filling of the reservoir and at the same time, to a disadvantage, increasing steadily the hydrostatic pressure on the gate. Movement of the gate continued in this manner to within 16 inches of closure and, at that point, it Diversion and Care of River West Bank. First-stage construction work for stream diversion consisted of an embankment and earth-filled timber crib which enclosed the right abutment and Monoliths 1 through 9 (Figures 125 and 126). This offered flood protection up to elevation 180 feet. A diversion channel through Monolith 8 also was excavated to prepare for second-stage diversion. The earth-filled timber crib was constructed in the foundation area of Monolith 10, and the remainder of the enclosure was an earth embankment extending upstream and downstream of the crib and tied into the right bank. This structure served as a precautionary measure in the event of a flood and did not actually encroach on, or divert, the normal flow of the Feather River. Channel. Second-stage stream diversion (Figures and 128) called for enclosure of the foundation area of Monoliths 10 through 19 and diversion of riverflow through a 15-foot by 15-foot opening through Monolith 8. Flood protection was to elevation 127 became immovable. Concrete blocks were then set upstream in the path of the opening. Progressively smaller rocks were dumped over the blocks, followed with application of earth and straw, until the flow was reduced enough to allow men to enter the opening. To control the remaining flow, a box chamber was constructed along the downstream side of the bulkhead at the invert of the opening by welding two 15-foot by 2-foot by '/j-inch steel plates together and to the bulkhead. A 10-inch gate valve was mounted on top at the end of a 5-foot pipe riser. A line then was connected and extended to the downstream end of the Monolith 8 opening, making it possible to open the valve and relieve hydrostatic pressure. Water leaking through the chamber at the invert level was collected by two French drains positioned along the invert and piped into the access gallery prior to placing the first lift of concrete. Before placing the second lift, the 10-inch gate valve was closed and the downstream section of pipe removed. After the third and last lift was placed and cured, grout was pumped into the French drains and also through grout system located in the the 15-foot by 15-foot opening to complete a preinstalled 180 feet. crown of Timber cribbing was set adjacent to Monolith 9, both upstream and downstream. The earth section of the cofferdam was composed of rockfill ballast, clay core, and sheet piling driven vertically through the core to sound rock (Figure 127). It was constructed to extend out into the River as far as practical without losing material by erosion. Prior to the closure attempt, rock was stockpiled at the River's edge on both sides near the upstream closure point. The actual closure was made from the left bank. To accomplish this, all available earth-moving equipment was utilized. Progress was slow due to erosion of embankment material nearly as fast as it was trucked in. At one time, large rock was positioned by the high line to check the loss of fill material. Work continued around the clock for three days before the closure was successful. When the River was finally diverted, the remaining cofferdam construction was routine. Two 36-inch the closure. Cofferdam sheet pilings, which were easily pulled, were salvaged by the contractor, and the more difficult pieces were left in place at the time of the first high water. Rains came in late October and early November, flooding the construction area on November 2, 1964. More flooding occurred on November 9 and wet weather continued intermittently into December. Heavy rain occurred December 18, 1964 and continued through December 23, resulting in a record peak flow of 253,000 cfs upstream of Oroville Dam. The peak flow at the Diversion Dam was reduced to 187,000 cfs by the restrictive action of the diversion tunnels at Oroville Dam. The highest elevation of the River at the Diversion Dam site was 206.7 feet. When the River subsided, the remaining cribbing that had not been removed had been washed out. The downstream cofferdam embankment was eroded to 150 i 13 87401 151 Fig ure 127. Channel Bypass, Closure, and East Bank Diversi?oanilan 034D 0\ (10A )n?Unolxno u. :1 (0.1.2.1320: .- I. V\hu In ?kin! ClixMunitihhu ll 1. hunt 045 \0 in Alt R. 03?) hlxu \xrxuxr umH dot \r bmu ?Obs-uhbhs not; l? A . 0115bhu?xxnwallr \rn} in \5 Pl! rdahVPSi5." . v( 3?s Ask?!- Bz ?53 :3 3253:: .x .tlihf Eta: .ti-hel: l1! . r: r. 3?1 ?tuitn! .. .im -521 Sir: 237:1}. \ilx..r.l..rr, \Lh . .k\\lnll 003:. )u 5 31.. {it ?53" hi: ONNWW .w R: Kazan ?23 .2 01? .F but ?trio 60:13:: i all}. fl: Elvivf~h v: ?11! 2! i h? 6:31 2 Fri; V1. .. 23.. (HI A?x)l? v? i h! .K u-l-l glitz .. .. an?: to! \{l3l $3 Ext. . Arnsk (up: A. it}: \u i .N ?9?33 . [43:33 . 3. ?Eli. Ax. Ix}. 5? 3i. .. 91500 m. 32.1131?. .1: \?xt i. 9510? I?m! i L. Ln: csxni??nox l? ME0-0 obtuunenuo-n ?ill Wt 50 #15:.5053In ?536. {?nk (.3 Nu. Ru K. .. ?11shears that cut diagonally across Monoliths 3, 4, and The fractured material was excavated to a depth equal to the width of the shear zones, which varied 5. from 3 to 5 feet. Foundation cleanup was done using high-pressure water hoses to remove most of the loose material. Loose and detached rocks were removed by prying. Air-water jets and pneumatic siphons were used for final cleanup. Figure 128. Cofferdam Cloture 1 SO feet and scattered along the river chanfew pieces of twisted sheet piling protruding through the muck and debris marked the location of what was once the cofferdam. In midsummer of 1965, the upstream portion of the cofferdam was leveled to elevation 175 feet by the contractor. elevation nel. A East Bank. The fourth stage of stream diversion consisted of the placement of an earth dike to provide flood protection for future closure of the railroad bypass, which was located at the left abutment of the Dam. Foundation Excavation. At the abutments, the overlying soils and weathered material were removed and wasted in the designated waste area. The exposed rock was found to be badly fractured. Further excavation by drilling and shooting was necessary to reach a suitable foundation. Grouting. Blanket grouting was used to consolidate areas of weathered or fractured rock and to seal open cracks and shear zones. Grout holes at spacings of 5 to 35 feet were drilled from 10 to 30 feet deep. Spacing and depth of holes were governed by the nature and extent of the foundation defects encountered. Most of the holes were inclined to penetrate steeply dipping seams and shear zones a few feet below the foundation surface. Holes normally were tested and grouted at 30 pounds per square inch (psi). Curtain grouting was accomplished from a 5-foot by 7-foot horseshoe gallery within the Dam between Station 5-1-70 and Station 12-1-25 (Figure 121) and from the surface of the excavated foundation beyond the limits of the gallery. The maximum spacing of the holes was 10 feet. Zone 1 holes, drilled to a maximum depth of 25 feet, were stage-grouted at pressures up to 100 psi. Zone 2 holes, drilled to a maximum depth of 75 feet, were stage-grouted at pressures up to 200 psi. Embankment Construction Description. The embankment provides flood freeboard only. No unusual problems were encountered in the placement of embankment. A major portion of the material was obtained in borrow areas close to the job site. The embankment material was divided into five separate classifications. Random Backnil. Random backfill with a max-^ imum size of 24 inches, free of organic material, was placed on the upstream and downstream faces of embankment. This material also was used as fill the for Streambed excavation consisted of removing river gravels that varied from 15 to 25 feet in depth. The exposed rock provided a satisfactory foundation, and it was not necessary to drill and blast as had been expected. A power shovel, end-dump trucks, and tractors were used to excavate and transport waste materials to a designated area upstream of the Diversion Dam. All material wasted within the reservoir was placed below dead storage, elevation 175 feet. Canal headworks excavation included a portion of the Power Canal, upstream and downstream transition wall foundations, headworks foundation, and the intake channel. The excavated material was used in the parking and storage area adjacent to the upstream face of the Dam and the service road adjacent to the downstream face of the Dam. the first-stage cofferdam. Consolidated Backfill. Consolidated backfill wa used in the trench for the 60-inch water pipe leadinj to the Feather River Fish Facilities. This material wa^ granular with a gradation specified for concrete sand Preparation. The foundation at Thermalito Diversion Dam is a blocky, well-jointed, metavolcanic rock which was easily cleaned. The only difficult area was a fractured trough formed by two intersecting 1S2 Impervious Core. Impervious core material w« placed from the canal headworks to the right abut ment. This material conformed to Oroville Dam Zon< of this volume 1 embankment described in Chapter V Select Backfill. Select backfill was placed behinc the retaining walls. The material conformed to Oro ville Dam Zone 3 material with a maximum size of I', inches. Zone 3 requirements also are described ii Chapter of this volume. V Riprap. Riprap was hard, dense, durable, rocl M'. 1 fragments free from organic, decomposed, and weathered material. It was obtained from canal excavation previously stockpiled and was placed on the upstream slope in such a manner that a well-graded blanket was produced. Concrete Production Construction Phases. Construction of Thermalito Diversion Dam was accomplished in four phases: (1) construction of Monoliths 1 through 9 and the canal headworks, (2) construction of Monoliths 10 through 20, (3) plugging the diversion opening through Monolith 8, and (4) filling the railroad pass through Monolith 20. During the second phase. Monoliths 1 through IS were left low during the winter of 1964-65 for passage of floodflows. After the River had subsided sufficiently in the spring of 1965, these low monoliths were completed to grade. Concrete Mixing and Materials. The concrete aggregates were stored in seven 320-cubic-yard timber bunkers. Clam gates at the bottom of the bunkers regulated the flow of the material onto a 30-inch conbelt. The cement used was Type II (low alkali) supplied by Calaveras Cement Company of Redding, California. Ice used as part of the mixing water for cooling the mass concrete was produced by an ice plant located on the job site. The bulk of the mass concrete was a 2 '/-sack mix with 6-inch maximum size aggregate. Mixes with up to four sacks of cement were used on a selective basis (Figure 129). The last day the batch plant was used to mix concrete for the Diversion Dam was October 6, 1965. From September 18, 1965 through November 9, 1965, concrete was transported from Oroville Dam batch plant. Transportation from this plant to the job site veyor was by transit mix trucks. For the remaining small-volume concrete items (curbs, control house, cable trench, radial-gate walls, and sill-plate blockouts), a portable concrete mixer was set up on the right abutment near the high line. Concrete for the diversion opening plug in Monolith 8 and the railroad bypass in Monolith 20 was obtained from Oroville Dam spillway batch plant. Concrete Placing and Formwork. Transportation of the concrete was accomplished in two stages. Eightcubic-yard, rail-mounted, side-delivery, transfer cars transported the concrete from the batch plant to the high-line dock. Attached to the high line was an 8cubic-yard bucket, which received the concrete from transfer cars and conveyed it to the placement area. I ; i I j I From October 1964 to May 1965, placing operations continued on a three-shift basis. With the beginning of summer weather and higher daytime temperatures, placing operations were restricted by state specification to two hours before sunset and two hours after sunrise. The contractor developed a nozzle that produced a fine mist or fog. Operation of this device over the concrete placement area reduced the surrounding temperature by 10 to 15 degrees, allowing the resumption of a three-shift concrete operation. The mass concrete in the Dam was placed in y'/j-foot lifts. Steel forms cantilevered from the previous lifts were used on the spillway monoliths. The cantilever supports were supplemented by rods welded to pins embedded in the previous lift. air The slotted bucket was formed by to hold the 2-foot by using screed rails form panels in place. As placement progressed, more panels were added until the surface was completely formed. After the concrete had set sufficiently, the forms were removed in the 6y2-foot order of assembly. Wooden forms for the dentates were constructed the job at site. Concrete was cured for ten days by continuous application of water with rainbird sprinklers and spray pipes. Concrete surfaces subject to direct sunlight were covered with burlap and kept wet by sprinklers. The bridge over the spillway section has 56 prestressed beams. For fabrication, the contractor constructed a jig on the right abutment within reach of the high line for ease of handling. Four beams were cast at a time, using the post-tension method for prestressing. Radial Gates and Hoists Spillway Gates. Spillway gates are 40 feet wide by 23 feet high. The gates were assembled by setting the two horizontal beams on a level H-beam jig. The four skinplate sections were then assembled and bolted loosely to the horizontal beams with the upstream face up. The skinplate assembly then was squared up and dogged where necessary before butt welding the skinplate sections together. After the gates were fully assembled, the joints between the horizontal beams and the vertical ribs and the edges of the back-up strip on the downstream side of the plate were welded by a single filler pass. The gate was turned over so the downstream face of the skinplate was up. The diagonal braces between the beams then were welded in place, the bottom struts were welded bracing the gate bottom, and the gate arms were bolted on. While setting the side seals to the required '/-inch compression tolerance, it was found that the "/«-inch adjustment of the side-seal angle bars did not provide the proper seal compression. The slots were elongated % of an inch for additional adjustment. Canal Headworks Gates. The assembly and stallation of the 26.67-foot-wide in- by 25.8-foot-high ca- nal gates were similar to the spillway gates, except that the arms were bolted on after the skinplate assem- bly was in place in the canal bays. The presence of the breastwall (Figure 124) prevented setting the gate as a unit. Hoists for Radial Gates. The first radial-gate hoist unit delivered to the job site was mounted on H-beams 153 154 Figure I29. location of Concrete Mixes Used in Dam S'rudure at 3 1- 31': sacx 2% MAX msE FROM LEVEL mm CAN as VIBRATED 4 SACK 3 2g sacx\ NON OVERPOUR MONOLITHS 3% TYPICAL SECTION I \lm/ 3 SACK I 1 ..J ?m?L?l THERMALITO DIVERSION 0AM 1 n-rvvr 3 SACK STARTING MIX ON ROCK CONCRETE MIX TYPICAL SECTION I ?6.6.9 PAGE Q. and used as a portable test apparatus. Each gate was checked for operation, and final adjustments were made on the wall and sill plates. The plates then were secured with second-stage concrete. As the remaining hoists arrived, they were installed, serviced, and checked for operation. Trunnion Beams and Stressing Operation. Trunnion beams were slipped over the tendons positioned in the piers and held to the correct elevation by fieldfabricated pipe stands. The center section of the trunnion beams was to be filled with grout. Instead, two 3-inch holes were cut in the two horizontal stiffener plates and later filled with beam encasement con- were on the upstream face of the Dam. the right abutment near the canal headworks releases water to the Feather River Fish Hatchery, and the other two are mounted side by side near the left abutment. One is a guard valve for the fixedcone dispersion valve, and the other is connected to a pipe stub for future use. The gates are of the rising stem type provided with stem extensions and their gates installed The one on installation was routine. Other Installations Installation of the outlet conduits, fixed-cone dis- persion valve, and sump pump system, ventilating system, electrical connections also was routine. crete. The trunnion beam tendons were post-tensioned by anchoring the jacking end of the tendon with grip nuts. This method of tendon anchorage proved satisfactory, as any loss of stress through seating of the wedge could be checked by returning the jack to the required pressure and checking the tightness of the nut. Slide Gates and Operators. Three 60-inch slide Reservoir Clearing Clearing of the Dam site and diversion pool area consisted mainly of removing scrub pine and oak. Instrumentation Instrumentation in Thermalito Diversion Dam consists of 64 foundation drains that are monitored quarterly and three crest tored annually. monuments that are moni- 155 BIBLIOGRAPHY Amorocho, J. and Babb, A., "Thermalito Diversion Dam Model Studies", Department of Irrigation, University of California, Davis, 1963. Department of Water Resources, SpeciHcation No. 62-05, "Specifications Proposal and Contract for Construction of Oroville Dam", Addendum No. 1, 1962. California Specification No. 64-25, "Specifications Bid Instructions and Bid for Furnishing Slide Gates for Thermalito Diversion Dam", 1964. , -, Specification No. 64-26, "Specifications Bid Instructions and Bid for Furnishing Fixed Dispersion Cone Valve and Operator for Thermalito Diversion Dam", 1964. Specification No. 64-43, "Specifications Bid Instructions and Bid for Furnishing Radial Gates and Hoists for Thermalito Diversion Dam", 1964. , _, Specification No. 65-47, "Specifications Bid and Contract for Electrical Equipment for Thermalito Diversion Dam," 1965. _, Beam Specification No. 67-40, "Specifications Bid Instructions for Thermalito Diversion Dam", 1964. and Bid for Furnishing Stop Logs and Lifting 157 GENERAL LOCATION SUTTER-BUTTEt CANAL OUTLET Figure 130. 1S8 location Map—Tharmalito Forcboy and Aftarbay CHAPTER VII. THERMALITO FOREBAY, AFTERBAY, AND POWER CANAL General Description and Location Thermalito Forebay is an 1 1,768-acre-foot offstream reservoir contained by Thermalito Forebay Dam on the south and east and by Campbell Hills on the north and west. It is located approximately 4 miles west of the City of Oroville. Thermalito Afterbay is a 57,041-acre-foot offstream reservoir contained by Thermalito Afterbay on the south and west and by higher natural ground on the north and east. It is located approximately 6 miles southwest of the City of Oroville. Dam Thermalito Power Canal, which also is included in this chapter, is a concrete-lined canal about 10,000 feet Figure 131. Aerial View in length. It conveys water in either direction between Thermalito Diversion Dam and Thermalito Forebay for power generation or pumping at Edward Hyatt and Thermalito Powerplants. Excess material from the Canal and other excavations was placed in recreation areas and shaped to make the areas more productive for recreation use. Nearest major roads are State Highway 99 bordering the west side of the Afterbay, State Highway 70 to the east of the Forebay and over the Power Canal, and State Highway 162 passing south of the Forebay and across the Afterbay (Figures 130, 131, and 132). Statis- summaries of the dams and reservoirs are shown and 13, and area-capacity curves are shown on Figures 133 and 134. tical in Tables 12 —Thermalito Forebay Figure 132. Aerial View — ^Thermalito Afterbay 159 — TABLE 12. Statistical Summary Dam and of Thermallto Foraboy Forebay THERMALITO FOREBAY DAM SPILLWAY No Type: Homogeneous and zoned earthfiU of Thermalito Powerplant bypass exceeds the peak maximum probable flood inflow. Should the bypass fail to operate, the entire volume of the maximum probable flood could be contained within the freeboard above the maximum operating eleva- 15,900 feet Lowest ground elevation at dam Lowest foundation elevation 170 feet 140 feet axis Structural height above foundation maximum tion. 91 feet 1,840,000 cubic yards Embankment volume Freeboard, The capacity 231 feet 30 feet Crest elevation Crest width Crest length.... spillway necessary 6 feet operating surface THERMALITO FOREBAY INLET-OUTLET Maximum operating storage Minimum operating storage Dead Thermalito Powerplant 11,768 acre-feet 9,936 acre-feet pool storage.. Maximum Maximum operating surface elevation Minimum operating surface elevation 225 feet 222 feet Dead 185 feet pool surface elevation. Shoreline, maximum operating elevation Surface area, maximum operating elevation.. Surface area, minimum operating elevation.. TABLE 13. Thermalito Power Canal Maximum generating flow Maximum pumping flow Thermalito Powerplant Bypass Capacity Statistical Summary of Thermalito Afterbay Dam and 142 feet 30 feet 42,000 feet 105 feet 103 feet axis Embankment volume 10,000 cubic feet per second Afterbay SPILLWAY No Structural height above foundation 16,900 cubic feet per second 9,000 cubic feet per second OUTLET 10 miles 592 acres THERMALITO AFTERBAY DAM Lowest ground elevation at dam Lowest foundation elevation _ _ 630 acres Type: Homogeneous earthfiU Crest elevation Crest width Crest length 16,900 cubic feet per second 9,000 cubic feet per second generating release Pumping capacity 15 acre-feet spillway necessary The river outlet capacity of 17,000 cubic feet per second exceeds the maximum probable flood inflow. Should the river outlet gates fail to operate, the entire volume of the maximum probable flood from both the Forebay and Afterbay could be contained within the freeboard above the maximum operating surface eleva- peak tion. INLET-OUTLET 39 feet 5,020,000 cubic yards Tail channel Freeboard, maximum operating surface 5.5 feet Maximum generating flow Maximum pumping flow OUTLET WORKS THERMALITO AFTERBAY Maximum operating storage Minimum operating storage Dead pool storage. Maximum operating surface elevation Minimum operating surface elevation Dead pool surface elevation Shoreline, maximum operating elevation maximum operating elevation.. minimum operating elevation.. Surface area, Surface area, 16,900 cubic feet per second 9,000 cubic feet per second 57,041 acre-feet 2,888 acre-feet 753 acre-feet 136.5 feet 123 feet 113 feet 26 miles 4,302 acres 2,190 acres River outlet: Gated structure through by dam — control, five 14-foot 14-foot radial gates 17,000 cubic feet per second Capacity Sutter Butte outlet: Four 7-foot-wide by 6-foot-high rectangular conduits control by slide gates on headworks discharge over measuring weir into open channel Design delivery 2,300 cubic feet per second — — PG&E lateral outlet: One 30-inch-diameter reinforced-concrete conduit control by slide gate in wet well discharge into stilling basin with measuring weir 50 cubic feet per second Design delivery — — Richvale Irrigation District outlet: Three 72-inch-diameter reinforced-concrete conduits control by slide gates on headworks discharge through Dall flow tubes into open channel 500 cubic feet per second Design delivery.. — Western Canal outlet: Five 96-inch-diameter reinforced-concrete conduits control by slide gates on headworks discharge through Dall flow tubes into open channel Design delivery 1,200 cubic feet per second — 160 — ELEVATION IN FEET AREA- ACRES IN THOUSANDS 5 4 23CHANNEL 225 NOTE 22? FOREBAY TERMINATES AT POWER 2.: CANAL STA. l26+00 CHANNEL ISO #550 CAPACITY-ACRE FEET IN THOUSANDS Figure 133. Area-Capacity Curves?Thermalita Forebay 161 AREA-ACRES 10 IN THOUSANDS 5 4 3 2 20 30 40 50 60 70 CAPACITY-ACRE FEET IN THOUSANDS Area-Capacity Curves —Thermalito Afferbay Figure 134. Purpose Chronology The purposes of the Forebay are to convey generating and pumping flows between Thermalito Power Canal and Thermalito Powerplant, provide regulatory storage and surge damping for the Hyatt-Thermalito power complex, and provide recreation. Since Edward Hyatt and Thermalito Powerplants operate in tandem and are hydraulically matched, the regulatory storage is utilized only for start-up and shutdown flow mismatch. The purposes of the Afterbay are to provide storage by the pumpback operation to Lake Oroville, provide power system regulation, produce uniform flow in the Feather River downstream from the Oroville-Thermalito facilities, and provide for the water required recreation. Outlets are provided to the Feather River and to furnish water to local districts where service from the River was interrupted by construction of the reservoir. Early in the 1950s, the original concept for power development downstream from Oroville Dam was to construct a number of small dams and plants within the Feather River channel. This concept later was modified to provide a diversion dam, a power canal, a power plant, and an offstream afterbay. A major consideration involved in selecting the offstream afterbay was that surges in the Feather River past the City of Oroville which would be caused by power plant releases could not be overcome in the onstream afterbay schemes. By 1957, a forebay was proposed for the development. In economic studies which followed, it was determined that any of three alternatives could be constructed for about the same cost: ( 1 ) the forebay as built, (2) a smaller forebay southwest of the Nelson Avenue Bridge, or (3) the originally proposed canal without any forebay. The forebay as built was selected because it could provide more operational flexibility, drainage problems could be minimized, and more rec- 162 i A pumped-storage concept had been proposed in 1957 but was not considered in these alternative studies. Eventual adoption in 1958 of pumped storage and raising the crest of the Afterbay Dam by 5 feet to provide reation could be provided. for the power necessary additional storage proposed forebay design. did not affect the Plans for Thermalito Forebay and Afterbay were completed in June 1965, a construction contract was awarded on October 18, 1965, and final inspection of the completed work was made on April 18, 1968. The Power Canal was constructed under a separate contract which was awarded on September 8, 1965. Work on this facility was completed in October 1967. Within months after storage began in the Afterbay (November 1967), high piezometric levels were observed along U.S. Highway 99 and farther west. In February 1968, the water level in the reservoir was lowered to about elevation 1 19 feet, and a program of exploration and reservoir bottom sealing was initiated. As the work accomplished under this program later was found to be ineffective, a number of pumped wells were installed along the west and south sides of the reservoir. Operation of this system of wells, termed the Afterbay Ground Water Pumping System, successfully lowered the piezometric level in the surrounding land. Regional Geology and Seismicity The oldest rock exposed in the forebay and afterbay the Older Basalt formation, a series of basalt flows which form the Campbell Hills. Three separate basalt flow members of the formation have been designated: Lower, Middle, and Upper. Two interflow layers of volcanic sediments separate the flows. Compact sediments of the Red Bluff formation overlie the basalt flows and form the dam foundations throughout most of the contract area. The Red Bluff formation is a flood-plain deposit ranging in classification from clay to gravel. Materials near the surface have weathered in place to clay, clayey sand, and clayey gravel. Leaching has created discontinuous iron-cemented horizons a few feet beneath the surface. Locally, streams have eroded through the surficial weathered zones, and excavations have shown that Red Bluff materials are cleaner at depth. Unconsolidated fine- to coarse-grained alluvium occurs along stream channels such as Ruddy Creek in the Forebay and Grubb Creek in the forebay and tail area is channel areas. Approximately 150 acres of alluvium, known as chapter as well as to Oroville facilities Columbia fine sandy loam (silt and lean clay), lie within the southeast corner of the Afterbay. Most of the Columbia soil is underlain at 10 to 15 feet by relatively clean sandy gravel. Dredge tailings, consisting of loose gravel overlying sands, cover the area between the Columbia soil and the Feather River and extend in both directions along the River for a distance of approximately 5 miles. The section on seismicity contained in Chapter V of this volume applies to the structures discussed in this Dam. Design Dams Description. Thermalito Forebay Dam is approximately 15,900 feet long with a maximum height of 91 feet and an average height of 25 feet. The 30-foot-wide crest is at elevation 231 feet, providing a 6-foot freeboard. This dam involves two relatively high sections joined by low reaches of embankment. The high portions are termed: main dam, located adjacent to Thermalito Powerplant, and Ruddy Creek Dam, located in the watershed near the Power Canal terminus. The plan of the main dam is shown on Figure 135, and sections and details of the entire dam are shown on Figures 136 and 137. Thermalito Afterbay Dam is approximately 42,000 feet long with a maximum height of 39 feet and an average height of 24 feet. The 30-foot-wide crest, at elevation 142 feet, provides a SYi-ioot freeboard at maximum operating pool. There is a 12-foot-high saddle dam approximately 1,000 feet in length at the northwest corner of the Afterbay. Sections and details of the Afterbay Dam are shown on Figures 138 and 139. The design intent was to construct basically homogeneous dams with locally available materials. Zoned embankments with more dredger tailings and basalt rockfill were considered but deemed too complicated for the heights involved. Therefore, slopes were flat- tened and more local material was used. The portion of the main Forebay Dam adjacent to the powerplant wingwall is the only location where a zoned section was required. The water side slope was steepened between the plant and Station 3 + 75F (Figure 135) to minimize encroachment into the approach channel. Transition to a flatter and more economical homogeneous section is completed at Station 5 + 50F. The land side transition from zoned to homogeneous section is completed at Station 2-l-OOF. Remaining dam sections for the Forebay and all sections for the Afterbay are essentially homogeneous with protective facing. Downstream blanket and toe drains, including perforated pipe in a trench filled with pervious material, were added to the homogeneous sections. Stability was determined mainby the Swedish Slip Circle method of analysis. In zoned sections, the sliding wedge method of analysis also was used. The infinite slope method was used to Stability Analysis. ly check the stability of all outer shell slopes. In addition to the reservoir loading at the full level and critical levels, a seismic acceleration of O.lg at other was ap- plied horizontally in the most unfavorable direction to each section analyzed. Material strengths were based on soils testing. Settlement. Foundation settlements were predicted to be negligible in all but the 91-foot-high main Forebay Dam. There, an embankment camber of 6 inches was provided. 163 164 Figure 135. General Plan of Forebuy Main Dom ?o to?. or rummage [no gn?uo '2 Foch I?ll-fora Sly,? glow] roe. manurg', SECTION 4-4 Soc/o 54.- 4 -53 ?27? 90:, 13-! rat dry/r cull(-dual/.1 04.! out" SAFETY - - Nun?v.7 - VAYEI In" um "amu- alum-Lu owl-Io- NIEIAV AID FOREBAV DAN Inn- w-vuu ncnou ?It?1 165 Figure 136. Forebay Dam?Section: and Doiailx 2' - no? . a 41.4., n) a? ground has \ae-cm 5 . '1le/?a . ?skierbyZara 4r 3r:g-nol ground 1m. "pneM am? 5 (ounce/tar! ?(Had . a Iguana.? mu k" 5 -4. DE 74.1 m: cuw runs?: 1' - 1' 1? 370:! or Dom 0.19.1 - :54" :5 .1 .3. mun,? A fat/Inform? mu: DETAIL ?4 .4 Sra?e I I. I I. u?n hum. a. 0., do 0 mu.? 0 TA 7'0 If ?37. IOF FOP way/v Dav gig DETAIL c; l'u- 41.7755 Indteo'vl "um: par mm . I: or man. our? 9 57a Jung .nqmal ground .quma/ g?lunt m. a can. an anti .0-) [he 5.. no,? arm?n. Kill 0: my SAFEYY - by .- WATEI Inn uvu ummu DMVILLI onus-on ":01?le MEIAV Ann AFTEIIAV FOREBAY DAM section: I DETAILS rr? I ontonk Nu I I858 .33 13 >20 :E4uIi: CoCDbiae 02.25 .2 In29:. ?3.36 .: (ucy? {?30 :5 .335 \n {on 3.2m 7 cc.? \ulvn \o Itch . a 33.950 to 3 23.. 3 :53 (3385.: cluxuuc? . It .Elxl c?tlxo >28 :31. on! I tin.? 3 (90 :le?gx. ~34 3- ti? ?3 \n (3533 \u 5? comm xv? fine; r? ?2.1x3?! 500:: Flag nuhmd I EGO so :oxu . . El. 9.: ?33. a: . sown . in .29.: In a: uc-?N an ?at: 1.. kooSn !n . . 33? 5 3:3 ioq Funax zotv?komq 2? 3:6 53 ?n 555 93 to I ip. m 'sf^ (U ru pi jijlf- D,' . ii' : I'. ^- Figure 146. Pacific Gas and ..... Electric Outlet 178 1 179 Figure 147. Paci?c Gas and Electric Outlet?Isometric View Hum-mo will (luv nu. couum "no? common noun (om-0 (mm mom? BK: um cm In zl-s luv. In a conno- accuse- maum I ucmc unmom "nu-mu noun-4m. I Accus Guvmc 0' . w" Mu mm? mm: ammo" i I WIACI (uvmany Ina-180 Figure 148. Su?er Bu?e Outlet ?53500Iall A'qu A: ran I a (web: 00? OI A own, Pa (In: cor on at a Olsen-19' prp- 1m rev a5 Lv a: "wolf On. an A ,1 ?oor wall anu' LM: no It.? 1 Nu- ru ,u 41209.500 _4 4! xrwo. I6- 0' ?ovum o- ,mvyc a ?1 (?53 6' 41 S'vvcruar '30 ~21: A 3? war; [Irv II7 5? I W1 c?h mt ?ma ?cw-Mr -. 4045? Mfudwc'tl\ i \1 mm :0<1 mw ?,Ja-twv - r. z. .44 TT nag" unuu? E?er?Valhg?. \Btlm Eluv ll7.5\n VV /f 1-9; vouch 75 :13 I Irncoa) Inr u" ?9?75 5 one-n rm: Anc- SIara Mn: yum-may. 960a 3 GENERAL PLAN star. [umv 5 A II (I - 553m; ?-32 0?41! :mumm 1mm lu?m 1-: I mm w; [Int-In! (1m? Ital nevi: Mo. ws [luv 136 .9 Tran. nm run. (Vev 12.1 3mm vg moreh llIJf/n9 HomI/ton and VI- IQ, gumd mu rue- 2 2 - .. Nam/Inn 90111 Can ~19. 7n'.ao 7/7375: SECTION X-x SCI. I 3/0- /smpm, mu Elev M1 51a? Isu Man I. - A [luv us: Mal w! '99 IlcnvaI-Cull/'1? cm") LA a mi s; [Tm-c. n? may rr m- ?um. 1:09-01 cu: .cIst-D OI: 00/6?6 01s costr'li? ?11: 1. Stal. (1.. m3 {5 an._laa_p . WM. 0 5 I 9N [martian hug, SECTION c-c 1' 20' 5: I ?Ovoa?a gunan." am u\ ?m sumI-r EW #03 .1 .4 runamn Irnl a SECTION 0- Scan ?11 7100 [luv-Inn lm: Q5) 6-6 3:01fonymu El'v o9. d. 'ch Or/yvnol ground IIM Dlpvap no 2 Eu?. ground Elly NZ 0 5?000167 w??rum/,M I :1 a?n'mn nu! a 1' run? Irnuwl an ., m'lch un/ anal-2? be . a/ ?61: DIS $7516.17? A mama; "any gnu-I a 1 Cowman .9 mnitr .I (outrun-am 5-. 00! 3f. [1'00 '00. m: 0W ll'f/rlt H40a,. mu? .m aponm; nu: In" awn: nun-o- FOIKIAY A SUTTER-IUTTE OUTLET I-m' ?rrl . In AD A I I 181 Figure 149. Su?er-Bune Ou?ef?lsome?ric View .x :55: n. x: a: .5. .9591. 0?5-30- to. . .I. 570:!- .3 .05 039.20 in. AVEQ x05. .5 .. v..153 9.350: n. . . .3 a 25:5: 2.2). to. 0393:..llpt:o 21:9 lli 53 033.KGB-avao. 21:. . .V 50 39n25. 05.9. m? Imulwr,? Hamlqo?o an." 1 "pay u? .. . . . Ivyqu?w I I 1 nouns on an; JNBIBDNVIHV WVIZNZD 1311n0 83MB "can." on "?le mum-3M uomAIo rmnouo nunnu un- um ?Jud-q up, if mm,? u?mnuu cog #:u'uau? ww- (nun-- ?on: Ind um: ?juzodtu1 IZLVA uzsvs . own-r; 3 2 a up a .5puq ?our goldAu: 13.411403 .vlpu? 4o; . . - . 1.3.4.613 u. In pm, cu on": an uv~ Imp ?ww-u 3 nu .v "u kuuc no: 0451491.,63 04 uncut "any"; 5mm, 1? SJJON m-r: A7NO NOLLVAVJX3 AF .73 01 JXIO an: AIM ount pnnw'u3\ uni 133v? 02-59: drawn "9 and Mama: 4'0 9504 ham: 06pm; or- I DID): 17"? ?man?: Havoc?, .vri15-0! 9&5 pool Inuit: 9: . o: 049 77 up49/, M/f/zx/ww on. n15- 4, gnaw-4 on var-lo 1. 4.?a?v la I. 3.19 Juana Mun-a4 \[upul punt puuarwa; _z 3 ?In 1? ,oo? new pvo: uwaq unIInAD-la o~ I nus ONV VAVDXJ 49 35' 0.1 nu: 5/054 pun: puaniy . 04 In mum ?Eu; ,o 03n14n? a? 4 ?1:qu -1 . I. a" M54170 po-cwha u: one luw ?av-4v plandw?jlz "2 1? .00: . ?444,7; ?5?94 pun: ~nn5?uaunA53-zio; - 3- Iva/1 3 .l 1 (anmm. ?nay to. I nu: 4c no.1 0.15/1 3? 0.4 snauwzrwa .10 11am F9 Iva/1 33$ l' my. .9 1.1" an? :0 (ow Euusr-a \wouuqmad: (ammo: pl:o,d a; may.? ?you 52m: o, a, wrl? um; pan? ,o 9.0&9 vau- JD Du) River Outlet Figure 150. \dwiu av: 182 15 87401 183 Figure 15]. River Ou?lef Headworks and Fish Barrier Weir?Isometric View mombolmuvon Imv. )msl Hum 21 nu ma tour-ct nous! 34- - WIOVI - I AIIGM ucmc Humor? uwmn (owmrm mmcnou WALKWAV ACCISS MOVOI CONIIQ (mm ("Guns 1- summon noun 'nun-u IINGVI In. to~cnm Nix SQIHN luv :21 a ?in msuc' my ?AuwAv unavn uwmu _4 I new main :0 (In! low mom ?Nam 07- Io wuuwm wuu suluci (uv. In 9 MINIMUM wuu sulud luvuam concur: Anon nu. Im a now wok uuovu or . .- (uv n: a sum? 3- . a. Relocations —^Thermalito Complex Construction of the Thermalito complex required the relocation of many utilities and roads serving the area. It also required, where relocation was not made, structures to cross the complex or abandonment of little used roads. Where abandonment took place, other facilities were provided to handle the traffic (Figure 130). Construction of the Power Canal required a bridge on the Oroville-Cherokee Road, the Oroville-Chico Road, and relocated Highway 40A (now State Highway 70). A bridge also was constructed across the Western Pacific Railroad relocation on the OrovilleCherokee Road. Power Canal construction also required the relocation of the Thermalito water treat- ment facilities. Construction of the Forebay required relocating about 4,600 feet of Nelson Avenue with a bridge across the Forebay. Construction of the tail channel and Afterbay required relocation of Oroville-Willows Road, State Highway 162, and abandonment of sections of TresVias and Larkin Roads. All facilities were replaced in kind or updated to the then-current design standards. The bridges were designed and built to AASHO specifications and the California "Bridge Planning and Design Manual". They were designed for like loading of HS20-44 or H20-S 16-44 with an alternate loading of two 24,000- The Department of Water Resources designed and constructed all the relocations except for State Highway 162, which was done by the State Division of Highways (now the Department of Transportation). Following is a brief synopsis of the work performed pound axles 4 feet apart. on each road. Oroville-Chico Road Bridge. The Oroville-Chico is a continuous, three-span, reinforcedconcrete, box-girder structure supported on reinforced-concrete abutments and two reinforced-concrete piers. The two end spans are 60 feet long and the center span is 150 feet long, for a total length of 270 feet. Total deck width is 36 feet - 10 inches which includes two 14-foot- 0-inch vehicle lanes and a 5-foot -11-inch-wide curb on the east side. The boxgirder is a three-cell unit 28 feet - 5 inches wide from outside to outside and 8 feet inches deep from the roadway deck to outside bottom. The two abutments are founded on spread footings, and the two 8-foot - 0-inch-diameter columns are cast-in-place and extended to a maximum of 44 feet below canal invert with a minimum penetration of 8 feet into sound rock. The entire structure was constructed prior to excavation of Thermalito Power Canal. This resulted in a shorter construction time with a minimum amount of false work required to support the cast-in-place super- Road Bridge structure. The 184 road alignment was shifted slightly to produce a more perpendicular and thus shorter bridge across the Canal. Oroville-Cherokee Road Overhead Crossing. The Oroville-Cherokee Road overhead crossing of the Western Pacific Railroad relocation is a 140-foot-long bridge which has a three-span, continuous, reinforcedconcrete, "T"-beam superstructure supported by reinforced-concrete piers and abutments. It provides a 32foot roadway consisting of two 4-foot shoulders. A 3-foot - 12-foot lanes and two 2-inch safety curb with barrier railing is located along one edge of the bridge, a 1-foot- 10-inch safety curb with barrier railing is located along the other edge of the bridge. and Oroville-Cherokee Road Bridge. The Cherokee Road Bridge across the Canal is Orovillea continu- ous, five-span, reinforced-concrete, box-girder struc- ture supported on reinforced-concrete abutments and four reinforced-concrete piers. The total length of the Bridge is 575 feet. One approach span is 65 feet long and the other is 110 feet. The lengths of the three interior spans are 1 10 feet, 144 feet, and 144 feet. Roadway width, sidewalks, curbs, and boxgirders are identical to the Oroville-Chico Road Bridge. The two abutments are founded on a cast-in-place concrete pile system. The four 8-foot-diameter reinforced-concrete piers are cast-in-place and extend 8 feet minimum into sound rock. Nelson Avenue. Approach embankments and a bridge across the Forebay were constructed on an alignment north of the existing road to minimize the bridge length. The east approach embankment overthe Forebay Dam. has a six-span, reinforced-concrete, "T"beam superstructure 430 feet long supported by reinforced-concrete piers and abutments. It provides a 28foot clear roadway, a 5-foot sidewalk, a 2-foot safety curb, and barrier railings on each edge of the deck. Five piers have been provided for future construction of a parallel bridge. lies The bridge Larkin Road. The Larkin Road Bridge was built county road which was severed by the tail to replace a channel. The Bridge has a four-span, reinforced-concrete, feet long supported by reinforced-concrete piers and abutments. It provides a 28-foot clear roadway, a 5-foot sidewalk, a 2-foot safety curb, and a barrier rail on each edge of the deck. Except for a short section of this county road, Larkin Road was abandoned south of State Route 162. Traffic from this road was rerouted to the Oroville- "T"-beam superstructure 265 Willows Road. (Recent maps indicate that Larkin Road has been renamed Wilbur Road and that old Oroville-Willows Road is now called Larkin Road.) The county agreed that sections of Tres-Vias Road across the tail channel and the Afterbay could be abandoned if other access was provided. A single bridge crossing was used on Larkin Road to provide access to the Tres-Vias Road. Oroville-Willows County Road. The OrovilleWillows County Road was relocated around the southern end of Thermalito Afterbay. The work consisted of slightly over 2 miles of new alignment with a bridge spanning the river outlet headworks. The bridge is 96 feet long with a simple-span, composite, plate-girder superstructure supported at the ends by the walls of the river outlet headworks. It provides a 28-foot clear roadway, a 4-foot - 1-inch sidewalk, a 1-foot - 7-inch safety curb, and a barrier railing on each edge of the deck. State Highway 162. Highway was placed bridge impreproject alignment. The total State on an embankment and 162 a 670-foot-long mediately south of its length of the relocation was 4,300 feet. The embankment has adequate width for expansion to four lanes while the bridge will carry only the present two lanes of traffic. Embankment was included in the afterbay dam construction. Construction Contract Administration General information about the major contracts for the construction of Thermalito Forebay, Afterbay, and Power Canal is shown in Table 16. There were two principal contracts. The first was for construction of Thermalito Forebay and Afterbay under the provisions of Specification No. 65-27. The most noteworthy features included forebay and afterbay embankments, tail channel, road relocations, outlet structures and gates, and installation of departmentfurnished equipment. The second was for the construction of the Thermalito Power Canal, Specification No. 65-37, which included earthwork, concrete lining, and turnouts for the Canal. TABLE 16. — Major Contracts Thermalito Forebay, Afterbay, and Power Canal Thermalito Forebay and Afterbay Specification Low bid amount Final contract cost Total cost-change orders Starting date Completion date Prime contractor 65-27 214,452,680 216,265,321 21,387,113 10/25/65 Guy 4/1/68 Atkinson F. Co. Thermalito Power Canal 65-37 35,549,348 27,061,410 21,222,438 Red Bluff formation and the other was basalt rock. Basalt rock extended from the Powerplant to Station 8-I-40F, while the remainder of the forebay dam foundation was Red Bluff formation. The foundation was excavated down to the basalt and curtain-grouted in this reach because it was economically feasible to do so. The grouting is discussed in a later section. The main dam included a deep cutoff trench where it is founded on the Red Bluff formation to control seepage into the tail channel. A pervious water-bearing stratum was found near the bottom of design depth for the trench. The trench was deepened and extended to Station 15 + 37F, the southern limit of the Ruddy Creek channel. The pervious stratum still existed at that point, but any extension of the trench would have required considerable excavation. The deep trench was terminated since the tail channel slope was about 1,000 feet away. This treatment was effective and seepage into the tail channel has not caused any problems. The method used to dewater the excavated trench was to place rock in drainage trenches on both sides of the cutoff trench invert and carry it above the limits of the wet zone. These trenches channeled water to 24and 18-inch, perforated, riser pipes (sumps) from which water was pumped by submersible booster pumps until the fill reached within approximately 2 feet of the top of the pipe, at which point the water was stabilized. The sumps were pumped dry, pumps removed, and immediately the riser pipes were backfilled with lean concrete. One and one-half-inch table riser pipes, on Co. Excavation — Excavation Forebay. Foundation excavation in Forebay was of two major types. One type was the —Afterbay. Foundation excavation in the Afterbay also comprised two major types. One type was the Red Bluff formation and the other Columbia loam. Red Bluff formation was treated in the same manner as in the Forebay beyond Station 15 Stripping. Foundations of both the Forebay and Afterbay Dams were stripped of all organic material and Recent alluvium. Stripping was approximately 10 inches deep under the major portion of the dams and over 5 feet deep in Ruddy Creek, Grubb Creek, and other small drainage channels. and and ex- laid parallel to the slope tended to the surface. They were used to grout the drain rock when the fill reached the top of the cut. Beyond Station 15-(-37F, the cutoff trench had a 12-foot bottom width with a depth of 5 feet except when pervious strata were encountered. Then auger holes were drilled to find the depth of the pervious strata, and deepening of the trench was accomplished if a satisfactory cutoff could be achieved within a maximum of 10 feet. If a satisfactory cutoff could not be achieved, a compacted impervious blanket 3 feet thick was added upstream, extending 100 feet from the toe of the dam. 10/7/65 10/15/67 Morrison-Knudsen Foundation the which were 24-foot centers, penetrated the drain rock + 37F. The Columbia loam area in the southeast portion of the Afterbay and in the vicinity of the river outlet required close attention to prevent uncontrolled seepage into the River. Areas under the dam and the 100foot blanket upstream of the dam were excavated to a depth of 3 feet to reduce the permeability, increase the strength, and assure removal of roots remaining from mature walnut trees that formerly grew in the area. 185 After excavating and grubbing operations were completed, the foundation was scarified, moisture-conditioned, and compacted with a 75-ton pneumatic roller prior to placement of Zone lA compacted embankment. Areas 400 by 2,000 feet, adjacent to Western Canal, were stripped to a depth of 2 feet and compacted. Once this area was compacted, the adjoining area received the same treatment, with the stripped material wasted on the previously treated area. Grouting. The grout curtain under the main Forebay Dam was continuous with the powerplant grouting and included the length of the dam resting on basalt foundation as well as an extension 100 feet out onto the Red Bluff formation (Figure 152). In this last area, emphasis was placed on grouting the rubble lens at their contact. Eighty-five holes were drilled on the curtain line in three zones: (1) from the surface to 25 feet and pressure-tested at 25 pounds per square inch (psi); (2) from 25 feet to penetration of the interflow in the basalt and pressure-tested at 50 to 65 psi, depending on the depth of penetration; and (3) maximum depth of 100 feet and pressure-tested at 75 to 85 psi. Grouting was conducted through a double-line (feed-return) system. Generally, the top 25 feet were tight; occasional holes took one or two sacks. Zone 3 holes also took only a few sacks of cement. Almost all of the grout was pumped into Zone 2 (interflow intercept) with one hole taking 614 sacks. Most mixes started at 7:1 and were reduced to 5:1 or 4:1. In addition, 29 holes were drilled for blanket grout- ing fault areas and for contact grouting at the wingwall of the Powerplant. They were bottomed normally about 10 feet deep. No grouting was performed in the Afterbay be- Figure 152. 186 Grouting Foundation of Foreboy Main Dan cause only Red Bluff and Columbia soils were encoun- tered. Embankment Materials and Construction — Impervious Forebay. Zone IF and 2F material in the Forebay Dam was generally coarser and less uniform than Zone lA material in the Afterbay Dam. Close attention was given to assure that the coarser portions of the Zone 2F materials were routed to the outer limits of the zones and Zone iF materials were blended by controlled excavation to make them homogeneous. Zone 2F material was compacted in all impervious portions of the embankment except for the designated Zone IF. Zone IF material was excavated from a stockpile located approximately 1,000 feet to the east of the main dam. Material was originally excavated from the Thermalito Powerplant area. Zone 2F borrow areas contained many different strata of fine and coarse material. Excavation was performed normal to the strata with scrapers loaded downward on the slopes to assure blending of the strata. Sand lenses that were exposed in the Channel "H" excavation were blanketed. Excavated material was transported to the embankment by scrapers and placed parallel to the dam axis in 8- to 10-inch loose lifts. It was then leveled and scarified with a bulldozer with a "Trinity Scratcher" or a motor patrol with a scarifier. The embankment lift was compacted with 12 passes of a sheepsfoot roller. All rolling was performed parallel to the dam axis, except where insufficient space prevented this procedure from being followed. Zone iF material placed in contact with the powerplant wingwall was compacted with hand equipment (Figure 153). A relative compaction of 97% was required for Zone IF and 95% for Zone 2F. Figure 154. Afterbay Dan Figure Placement of Zone 4A —Afterbay Dam When embankment showed an insufficient relative compaction, the areas were reroUed or the material pass of a 54-inch vibratory roller on removed and wasted. fied. — Impervious Afterbay. Suitable material excavated from the cutoff trench was utilized to backfill the already excavated cutoff trench or was compacted as Zone lA embankment. The main source of material for Zone lA embankment was required channel and Approved borrow by the contractor also were used. The structure excavation. areas selected specifications allowed the contractor to spoil required excavation and excavate for borrow at his own expense to shorten haul distances. Transportation and placement of the Zone lA were performed in a manner similar to Zone IF and 2F placement in the Forebay Dam (Figure material 154). Pervious —Forebay. Zone 3, a sandy gravel, was placed on the entire upstream face of the dam and at designated areas on the downstream side. Zone 4F material, basalt rockfill, was placed on the entire downstream face of the Forebay Dam and on the upstream face at designated areas. It was obtained from two places: Borrow Area Y, an extension of the inlet channel to Thermalito Powerplant, and stockpiled powerplant excavation. Prior to placing Zone 3 and 4F material, the contractor elected to construct the Zone IF or 2F embankment to about dam crest elevation. This resulted in a restricted working area which precluded compaction i 155. by the specified method of four passes of the treads of a crawler tractor. Tests of alternate compaction methods with vibratory rollers showed that one pass of a 72-inch vibratory roller on Zone 3 material and one would result in compaction Zone 4F material slightly higher than speci- Consequently, this method of compaction was adopted throughout the operation. Both zones were loaded at the source with rubbertired loaders and transported to the embankment in A bull- dozer was used to spread the material in 12-inch lifts. 16-cubic-yard, Pervious bottom-dump, highway —Afterbay. trucks. Placement of Zone 3 and 4A material consisted of a blanket of Zone 4A material on the entire downstream face of the dam (Figure 155) and Zone 3 material on the upstream face of the dam. Zone 3 material was obtained from Borrow Area Z. Most of Zone 4A material was excavated from the river outlet structure area, with the remainder from optional borrow areas. The contact point between Zone lA embankment and Zone 3 and 4A material was watered and wheelrolled with loaded trucks. Transportation and placement of material were accomplished in the same manner as for Zones 3 and 4F in the Forebay. Riprap was hauled to the dams utilizing trailer rigs and dumped in stockpiles along the upstream toe of the dams. Placement was performed with rubber-tired front-end loaders with chain wrapping on the front wheels for better traction (Figure 156). The loaders carried the rock from the stockpiles to the top of the slope and windrowed a lift for a distance of 50 to 100 feet longitudinally, then added another windrow below it. This procedure was continued until the bottom Riprap. end-dump highway trucks and was reached. "Top-Out" Operation. A small, self-loading, paddle-wheel scraper; a blade; and compaction equipment 187 Figure 156. Riprap Plor were employed to finish the top 2 feet of the impervious portion of the dams because they were too narrow for larger equipment to maneuver. The pervious portions of the dams were brought to grade at a later date. The top surface was fine-graded and a 4-inch layer of the aggregate base material was placed. The aggregate base material was trucked to the embankment from a screening plant located at Borrow Area Z. Once at the embankment road, the material was dumped in two windrows, one on each half of the road; a spreader box was used to distribute the material to the required thickness and width of the road. After spreading was completed, the surface of the road was bladed and compacted with a three-legged roller. Final compaction was performed with a vibratory roller. Thermalito Power Canal Canal excavation was started west of 70 using double-bowl diesel-electric scrapers. Excavation progressed eastward in a pioneering fashion, with the contractor constructing haul roads to and from various spoil areas prior to serious excavation in any particular area. Spreads of scrapers with bulldozers later were added to the excavation Excavation. State Highway effort. Nearly all of the excavated material required ripping prior to its removal with scrapers. Bulldozers operated singly or in tandem to push-load the nonelectric scrapers. Electric scrapers were self-loading with all eight wheels pulling but occasionally needed assistance. Softer earth material was excavated with the electric scrapers while the others were used mostly in weathered and decomposed rock, in wet areas, and in the small confined areas of the canal prism. The rate of production in the canal excavation averaged 25,000 to 28,000 cubic yards per eight-hour day. 188 Between the Oroville-Cherokee Road Bridge and the Oroville-Chico Road Bridge, areas of unsuitable material were encountered below the elevation of the canal invert and beyond the established slope lines above the operating roads. These areas were overexcavated and refilled. The invert was refilled with compacted embankment or with Type B filter material, depending on the subsurface water conditions encountered. Side slopes above the canal lining were filled with free-draining material from canal excavation to eliminate slide conditions. Bedrock was drilled and shot. Typical drill holes were 20 feet deep on 8-foot centers. Shot rock was loaded into dump trucks with front-end loaders and, using the canal invert as a roadway, the material was hauled to the designated riprap stockpile area or wasted in spoil areas. The stockpiled rock was used as riprap on the forebay embankment under the Thermalito Forebay and Afterbay contract. More than half of the excavated rock broke into pieces too small to be used for riprap, even though normal rock excavation methods were used. The high from weathered shear zones or loss probably resulted closely spaced joints in the bedrock. A total of 207,000 cubic yards of excavated rock was stockpiled. Beginning in early August 1966, the first indication of serious slide trouble became apparent when earth slides developed in both cut banks 1,000 to 2,000 feet west of Oroville-Cherokee Road Bridge. Fissures and cracks observed at various other locations along the canal gave evidence of possible future slides. These slides and indications of slides were not of any great magnitude at first; however, attempts to remove the slide material triggered further movement. The slides were attributed to failure, or "breaking down", of unsupported lone formation clay, which was exposed during canal excavation (Figure 157). After the first earth slides, seasonal rains com- menced which further aggravated slide conditions. Existing slides became more extensive, and new slides developed in areas where the slopes had been standing satisfactorily. Additional movement of the earth slides west of the Oroville-Cherokee Road Bridge blocked the canal invert, causing surface drainage water to pond for a distance of one-half mile. Consequently, the contractor was directed to let the earth slides stand until studies were made. It was concluded that the slides should be removed and replacement of the slide material with compacted backfill began in early February 1967, on a two-shift-per-day schedule, five days a week. Later, the contractor went to a three-shift schedule, six days a week. Corrective work was completed in May 1967, and all canal excavation was completed in June 1967. Horizontal Drains. In areas where ground water was found seeping through the cut slopes, horizontal drains were installed to intercept and remove this subsurface water. Average depth of the holes was 172 feet, with a depth range of 80 to 300 feet. At several locations, stalled in the canal Figure 158. Placing Type B Filter II Drain Pipe Along Toe of Slope and Type Material on Invert of Power Canal horizontal drains were in- prism below the operating roads. These drains were not anticipated in the design, so a contract change order provided for a collector system and for disposing of the water. These drains extend through the canal lining. \ Type A filter material was placed clamshell a few inches below final grade prior to the trimming operation, with the remainder being placed by the lining machine at trimming. Where Type A filter material was found to be above elevation 218 feet, it was removed and replaced with Type B filter by means of a cutoff plate attached to the front of the lining machine (Figure 158). Type B filter for rock sections also was placed on the slopes by a clamshell and trimmed with a lining machine. Filter material in the invert was spread with a motor grader and trimmed concurrent with trimming of the side slopes. Filter material was placed by clamshell and I trimmed I in other areas inaccessible to the lining Filter Subliner. with ' I I : I I a to line and grade by less automated methods machine. Concrete. The canal lining consists of 6-inchthick reinforced concrete with transverse grooved I j joints I on 1 5-foot centers. One longitudinal construc- was placed at the canal centerline. Longitudinal grooved joints were placed on 5-foot centers on the side slopes and at distances of 7 feet and 20 feet on tion joint i 1 j ] leach side of the centerline in the invert. Reinforcement steel for the canal lining consists enof No. 4 bars placed on 12-inch centers each iWay. Precast mortar spacers were attached to the steel, land the invert and side slope mats were placed on the ifilter blanket with a mobile crane (Figures 159 and j jtirely I 160). Figure 160. Reinforcing Steel Being Placed in Conol Invert 189 The contractor's paving (lining) train was made up of a lining machine followed by a finishing jumbo and a curing jumbo. The jumbo spanned the full width of the paving operation, one side slope and half the invert. power machine was supplied by a mounted over the low driving track. Travel and support were provided by two independent tracks driven by an electric motor mounted on each unit. Line and grade were controlled by elecAll to the lining diesel motor-generator probes attached to the lining machine, activated by piano wire stretched along the invert and the opertric ating road. Concrete was delivered to the lining machine by 8-cubic-yard mixer trucks and deposited on a belt which conveyed the concrete to a 4-cubic-yard, traveling, dump car mounted on the front of the lining machine. Consolidation of the concrete was accomplished by horizontal vibrators running the full length of the lining machine and mounted in the bottom of the baffled hopper at the finish gradeline. Once the concrete was consolidated, it passed under a smooth pan located below the structural members of the machine. Beyond the smooth pan, there was a short gap; then the concrete passed under an 18-inchwide floating pan. The longitudinal grooves were cut first using cutting edges protruding 3 inches below the lining machine's leading pan. The transverse grooves were cut by transverse bars located at the rear of the lining machine which were forced into the concrete by hydraulic rams aided by vibration. The grooved joints obtained by this method were not satisfactory. They required more hand finishing than appeared practical, so other methods were explored. The contractor finally elected to place plastic strip joints both longitudinally and transversely. Observation of the breaks and appearance in the lining at the plastic strip joints indicated that good results were obtained. Concrete placements, referred to as "hand lining" were made in areas inaccessible to the canal lining machine and in the transition area west of State Highway 70. A small paver (Figures 161 and 162) was designed by the contractor and used to place concrete in these areas. Concrete placed was well consolidated and required only a small amount of hand finishing. The cove at the toe of the side slopes was placed first in alternating IS-foot sections. Side slopes then were placed in the remaining 15-foot-wide sections. Alternating the initial concrete placements provided a firm foundation and solid side forms for the paving screed during the final placements. The invert was placed last. The operation that actually controlled construction progress on the canal lining was the concrete finishing. Concrete repair was required in a few areas that were placed in the early part of the lining operation. Concrete for the canal lining was produced in an automatic batch plant located to the right of the canal, 190 Figure 161. Slip Form Lining Operation on Thermalito Power Canal Transition Slopes west of the Oroville-Cherokee Road Bridge, in Spoil Area B. Concrete temperature control was accomplished by the addition of ice to the batch water. The contractor was able to maintain the temperature at or below 80 degrees Fahrenheit. Structural concrete was delivered to the transit mixers from a commercial plant. site in Weeps. Due to anticipated problems and slow rate of progress in installing the canal weeps as designed, plastic tube-type weeps were substituted. The plastic weep consisted of a 2-inch-diameter by 12-inch-long tube, conical on the bottom and open at the top with an internally fitted plastic cap. Weeps were installed by placing each weep over a steel insert and driving it into the wet concrete. Stone Protection. Where the canal section is 400 gave the contractor the option of placing crushed stone or rock material obtained from the canal excavation or other sources. The contractor interpreted this as allowance for the use of uncrushed river gravel screened from local Feather River aggregate sources. However, it was the Department's intention to require the use of crushed or angular rock material not round, uncrushed, river gravel. Consequently, a contract change order was issued clarifying the requirements. feet wide, the specifications — Recreation Area. In cooperation with the CaliforDepartment of Parks and Recreation, site preparation work for the north forebay recreation area adjacent to State Highway 70 was included in the power canal contract. This recreation area originally consisted only of a spoil area, but a contract change order provided for a swimming lagoon and beach adjania cent to the spoil area and canal outlet. Closeup of Slip Form Lining Operation on Thermalito Power Conal Transition Slopes Work in the area consisted of clearing and grubstripping embankment foundations; placing compacted embankment for access roads, parking areas, and building pads; placing 24-inch-diameter, corrugated-metal, pipe culverts and culvert markers; final shaping and grading to the design contours; and the construction of a 24-foot-wide, reinforced-concrete, boat ramp. A separate contract change order provided for the application of a soil sterilizing agent to a beach area prior to placement of aggregate base material and processed sand. bing; Tail Channel Dewatering was performed with one 6-inch, one 8-inch, and one 12-inch, 50-horsepower, centrifugal pumps. Water was piped to the Van Excavation. Gilder drain about 1 '/j miles west of Larkin Road. In some areas, the bottom of the excavation became too saturated due to excessive ground water and would not support the weight of the scrapers and other equipment. In these areas, material was excavated with draglines. Where overexcavation occurred, the areas were brought back to grade with Zone 4F Usable material from the tail channel was placed in appropriate zones of the forebay and afterbay embankments and the remainder was wasted. Final trimming of the slopes was performed with a small bulldozer, and the invert was brought to grade with a material. blade. Placement of Channel Protection. Upon completion of slope trimming, placement of the stone slope protection and bedding material commenced with a Gilli-K-Hike (Figure 163). Power to the belt was provided by a diesel engine-generator mounted adjacent Figure 163. Bedding Placement on Tail Channel hopper on a platform at the bottom of the maand the power to move the unit was provided by a bulldozer located on the operating road and a rubber-tired side-dump truck on the invert of the channel. Stone slope protection and bedding material were transported with side-dump trucks. The bedding material is dredge tailing sand and gravel which was processed at the Thermalito Powerplant batch plant. The slope protection is the same material as forebay to the chine, 4F. An average of approximately 1,000 feet of slope protection was completed per two-shift day. Zone Invert protection material, which is the same as slope protection material, was trucked with bottomdump and end-dump, 18-wheel, highway trucks from Borrow Area Y and Zone 4F stockpile and spread with two large bulldozers. Final grading was performed with blades. Immediately after placement of the invert protection was completed, the sump pump located at Larkin Road was removed, and the ground water was allowed to fill the channel invert. Miscellaneous Channel Excavation Channels "A" through "G" are located within the Channel "H" is within the limits of the Forebay (Figure 164). They were excavated through high ground to provide hydraulic limits of the Afterbay while continuity in the reservoirs. The contractor exercised his option of extending minimum lines of Channels "A", "C", "D", and "H" to obtain suitable materials for embankment at the reduced haul distances. Sand strata that were exposed during the excavation of several of the channels were blanketed with a layer of impervious material. 191 ?2 Figure 164. location of Miscellaneous Channels 90?! i A- .u CHANNEL .r a? 4 cu.? A A 9.3? 1 CHANNEL A . -ron:an . an). CHANNEL TAIL CHANNEL CHANNEL N..- CHANNEL ~r ?r CHANNEL . 1mm" I ?l 1 ?m?n Oin'?u?Maout": (Jilly-a I I all! yawn-u! oo'o'o . man-'W a low ?uua-uv r? in: as: SAFETY - - Nona-my - WATER nun mun?A nuAmm vum allow-ten nun-aa? o- numu no nu: Inu- ummu onov-ul owns-on YNERMALIVO FOREBAV ANO INDEX TO PLANS -.T.u (Jam; .6494" I gum?! EJIMAIL Irrigation Outlets Western Canal and Richvale Canal. Western Canal and Richvale Canal outlet structures were built immediately north of the existing canal alignment so that the canal could be used during construction (Figure 165). At the upstream end, the structures are connected by a retaining wall, footing, and cutoff wall. The entire area between the two structures and the adjoining area for the structures themselves were excavated in one operation. This made dewatering easier since drainage channels could be cut across the entire area and fewer sumps were required. Dewatering was accomplished by digging trenches around the structures. These trenches led to sumps where the water was pumped out and discharged into Western Canal. Two weeks after commencement of discharging water into Western Canal, it was discovered that a delta was developing in the Canal from sediments deposited from the pumped water. Subsequently, water from the excavation was discharged onto the ground where it either evaporated or seeped back into the ground. The foundation for the main cutoff wall was overexcavated and formed instead of placing concrete directly against the excavation. The cylindrical forms for the five 92-inch-diameter (Western Canal) and three 72-inch-diameter (Richvale) Dall tubes had to be anchored securely because they were subject to extreme uplift pressure as the concrete placement was brought up. It was difficult to place concrete under both the flow tubes and thimbles embedded in concrete at the barrel intakes without developing voids. These voids were filled by drilling a hole at the lowest and highest points of each void and pumping grout into the lower hole until it came out the upper hole. Holes in the metal were filled by threading the hole and screwing a plug into it. Plugs were ground until flush with the walls. Each exit wall was placed in three sections. The first was formed, the concrete placed and allowed to set, and the forms stripped, usually in about 6 days. Fill then was compacted behind the wall. In this case, however, the contractor was directed not to strip the forms until test cylinders showed a strength of 2,500 section psi to assure that the stress at the base of this concrete section due to the backfill load would not be exceeded. For the two sections most removed from the outlet the slope was flatter and material was placed behind the walls to grade. Concrete then was placed from trucks and finished with a slip form that moved up and down the sloping surface. structure, PG&E Lateral. This structure is a single-barrel 30-inch-diameter conduit approximately 180 feet long, with a small intake and exit works. Structural excavation was performed with a backhoe for the conduit section and with a bulldozer for the exit structure and weir. Minor adjustments were made by hand labor for the cutoff collars and the float well. Concrete placement began with the bottom sections of the six cutoff collars. Subgrade slabs of the inlet, exit, and wet well were placed next. Conduit concrete (Figure 166) was placed in a series of sections as determined by construction joints. Each section was placed in two lifts, the first of which was made with the inside conduit forms and all of the reinforcing steel in place. The concrete was placed in the bottom section and brought up to a level an inch or two below the invert. This anchored the reinforcing and inside forms, thus preventing the forms from floating during the placement of the second lift. Outside forms then were installed and weighted in place and the second lift placed through the top. Placement of the downstream transition section and hoists. Canal excavation was performed in conjunction with the structural excavation. The small plug at the entrance to the old Sutter-Butte Canal was removed during the closure sequence. Rough excavation was performed with scrapers, steel, slide gates first lift sitioned and epoxy-bonded concrete replacement made Sutter-Butte Canal. Sutter-Butte outlet structure (Figure 167) consists of an approach and headworks section, four 6- by 7-foot rectangular conduits approximately 340 feet long, and an exit structure. A rectangular, modified \'-notch, sharp-crested weir was constructed 370 feet downstream of the exit structure. Incorporated in the headworks section are 4- by 6-foot, in- of the exit piers. Embedded in these piers were the downstream stoplog guides. During placing operations, movement of the forms pushed the right exit wall guide out of plumb by more than inch parallel to the structure centerline. It was re(>o1 cluded the in 2-foot was lifts. Construction of the slabs and walls of the upstream approach and headworks (Figure 169) was done similar to those of the exit works. Higher wall placements were made in two lifts, the maximum height being 14 feet. Headworks piers were made in three lifts with the breastwall concrete incorporated in the top two lifts. The counterforts were placed to full height in one lift. River Outlet The river outlet structure (Figure 170) is located in the southeast corner of the Afterbay (Figure 130). Prior to commencement of excavation, sheet piles bulldozers, a were driven and rubber-tired backhoe. During structural excavation for the headworks structure cutoff collar, water-bearing pervious strata were exposed. As a result, the approach channel was blanketed with impervious material and the structure backfill modified to increase the length of the water percolation path. Dewatering was accomplished by excavating drainage ditches along the outside of the conduit slab and by utilizing the cutoff collar excavation as cross drainage. Bottom slabs of the conduits were placed in alternate 25-foot-long sections for the full width of the structure. The walls and top slab of the conduit sections were placed next, in a like manner (Figure 168). the entire width of the canal just downstream of the fish barrier structure to keep the river water from entering the construction site. Immediately upstream of the cofferdam, two electric centrifugal pumps, 8- and 12-inch, were installed to pump the ground water from between the fish barrier and the cofferdam into the River. Another cofferdam was built just downstream of the headworks structure for flood protection purposes during the rainy season. During the winter months of 1966, the ground water between the two cofferdams was allowed to reach the water surface elevation of the River, thus equalizing the hydrostatic pressure about the cofferdam at the River. After the rainy season, the water once again was removed and construction proceeded normally. motor grader, and a backhoe. Final trimming was performed with a small bulldozer, and cutoff collar excavation was performed with a small Figure 167. 194 Sutter-Butte Conal Outlet Figure a 168. cofferdam was constructed across Sutter-Butte Canal Outlet Conduits Figure 169. Sutter-Butte Canal Outie; Figure 170. '.r.:^:.^ Headworks. The headworks structure was built on in-place gravels. The foundation was excavated to elevation 95 feet and brought back to subgrade with compacted, semipervious, Zone 3A material. Subgrade was at elevation 101.0 feet for the entrance slab and at elevation 99.5 feet for the radial-gate slab. Blockouts were provided in the piers to receive the radial-gate wall plates. This permitted the wall plates to be adjusted to final position with the radial gates in place. Stoplog guides were installed upstream and downstream from the radial gates. The county road bridge and service bridge slabs were hand-screened and finished without the aid of a mechanical finishing machine. Each bridge slab was covered with carpet and kept wet for curing. The county road bridge abutments and the radialgate end walls were counterforted without using horizontal construction joints. River Outlet Fish Barrier Weir. The fish barrier weir structure (Figure 171) is located on the bank of the Feather River approximately 860 feet southeast of the river outlet headworks. A hammer, powered by compressed air supplied by a 900-cubic-foot-per-minute rotary compressor, was used to drive the sheet piling cutoffs under the weir. The downstream cutoff was driven to tip elevation 80 feet with head or cutoff elevation 99 feet in the channel invert. Upstream sheet piling was driven to tip elevation 60 feet with head or cutoff elevation 101 feet in the channel invert. No difficulty was encountered in driving the downstream sheet pile tips to elevation 80 feet but, when the upstream sheet pile tips reached elevation 70 feet, 1-inch penetration required 150 to 300 hammer blows. It was agreed that 150 blows per inch of penetration of the sheet piling would be ac- cepted as refusal. Figure 171. River Outlet — Fish Barrier Wei 195 The structural excavation was performed by a dragwith a 3-cubic-yard bucket and end-dump trucks. Excavated material was wasted in old dredger ponds or used for channel dikes between the fish barrier and the river outlet headworks. Sheet piling was capped by the concrete slabs of the structure. Concrete for the 3:1 sloped exit slabs was placed using slip forms. Face forms for the ogee crest of the weir were stripped within two hours after concrete was placed, line and all surfaces received a hardwood float finish. Falsework to support the service bridge slab was composed of 6- by 8-inch bents with 6- by 6-inch caps. Telltales were used to check any deflection during concrete placement. The maximum deflection was '/ inch. The slab surface was hand-finished without any problems. Concrete Production Except for two sections of the river outlet approach, walls and minor drainage structures, all structural concrete used on the afterbay outlets was produced at the batch plant located at the site of Thermalito Powerplant. The remainder was produced at a plant in Oroville. Control of actual batching operations was done by department personnel. Concrete was transported from the Thermalito Powerplant batch plant by agitator trucks with an 8-cubic-yard capacity. The remaining concrete was delivered to the job from Oroville by various transit mixers, ranging in capacity from 6 to 1 1 cubic yards. Water cure was required on structures for a period of 10 days. This was accomplished by covering the structures with water-saturated carpets kept wet by soaker hoses. Carpets were kept in place for 4 days Closure Since no flowing stream or irrigation ditches existed in the Forebay, closure did not present any problems. In the Afterbay, the main closure problem centered around the Western Canal. The outlet structure was built adjacent to the existing canal and, upon completion in the spring of 1967, the Canal was rerouted so that water ran through the completed structure and the dam was constructed across the old canal alignment. The original inlet for Western Canal on the Feather River had to be maintained until the Forebay was filled and could feed Western Canal through the tail channel. At that time, October 1967, the Afterbay Dam was closed across the old Western Canal just north of the river outlet. Closure of the Sutter-Butte Canal presented no problems because it was possible to supply water through existing facilities outside the Afterbay during the period of closure. The PG&E lateral canal was shut down during the period of closure, and Richvale Canal was not yet in service when the Afterbay was constructed. Instrumentation and Toe Drain Observations Instrumentation was observed from the time of inthroughout the entire construction period. After filling of the reservoirs, flows from the embankment toe drains were estimated to average less than gallon per minute (gpm), and many drains remained dry. No unusual settlement or alignment deviations are evident in the embankment nor is there any evidence of deterioration of slope protection. stallation '/^ Seepage following the 10-day curing period. Membrane curing was allowed on subgrade placements, surfaces to be backfilled, and scattered miscellaneous structures. Membrane curing compound was Forebay. When the Forebay was filled, water in the piezometers between Stations 78 + 00 and 91+00 rose rapidly. Seven relief wells failed to alleviate the situation and, by April 1968, the piezometric surface was above ground level. The situation was corrected in September 1968 by drilling 11 more wells and'col- white-pigmented "Hunts". lecting water in an open ditch, then pumping back June 1969, the system was im- into the reservoir. In Reservoir Clearing Clearing was required within the entire construction area and the entire area below the maximum reservoir water levels. Within the cleared area all trees, structures, and obstructions were leveled to the existing ground line and all combustible material was burned. Grubbing was required only under embankment foundations where tree roots, pipes, or other material were buried within the top 3 feet of the foundation. Trees were pushed over with a large bulldozer, and the roots were removed with a ripper attachment on the same equipment. All known wells within the reservoir and wells that were discovered during the course of construction were backfilled in accordance with specifications. Designated wells located outside the reservoir were preserved for observation of piezometric levels. 196 proved by cutting off the well casings about 4 feet below ground level and installing a 10-inch, perforated, asbestos-cement pipe to interconnect the relief A 100-gpm submersible water to the reservoir. wells. pump now returns the Afterbay. A similar situation was observed along 99 when the Afterbay was filled. After lowering the water surface and an unsuccessful attempt to blanket probable sources of leakage with bentonite, the Afterbay Ground Water Pumping System was Highway proposed and implemented. The Afterbay Ground Water Pumping System involves 15 irrigation-type wells spaced around the west and south sides of the reservoir. Eleven of the wells are along the west side, situated between the dam and Highway 99. The remaining four are located on the south side along Hamilton Road. The total pumping capacity is about 28,000 gpm. The purpose of the system is to mine the ground water on the immediate land side of the dam, thereby lowering the piezometric level in the surrounding ground. The pumped water is returned to the After- and resistivity tests on the drilled holes. Each pump is controlled separately by start and stop probes set at the desired high and low ground bay. Tail Channel. Excavation of the tail channel exposed an area of pervious material in the left bank just downstream of Thermalito Powerplant. This area has been monitored for seepage and signs of movement. Seepage from the Forebay enters the tail channel through this stratum but has not caused any damage or movement. This is considered beneficial since it lowers the water table in the area, alleviating the need for relief wells outside the Forebay adjacent to the Criteria used for setting the number of wells, their and location included data collected from the size, ground water monitoring program, topographic low points, known geologic data under the floor of the reservoir, results of two aquifer pumping tests, and availability of land. The total depth of each well was based on judgment of interval of aquifer intercepted to produce an adequate drawdown. The depth of casing and perforation was determined from drilled logs water level. Powerplant. 197 BIBLIOGRAPHY Bucher, Kenneth G., "Hydraulic Investigation of the Thermalito Afterbay River Outlet", Water Science and Engineering Papers 1029, Department of Water Science and Engineering, University of California, Davis, June 1969. California Department of Water Resources, Bulletin No. 117-6, "Oroville Reservoir, Thermalito Forebay, Thermalito Afterbay: Water Resources Recreation Report", December 1966. 199 GENERAL LOCATION BVHON TRACT DELTA FISH»«" PROTECTIVE FACILITY EL DELTA PUMPING* PLANT N> TRACY PUMPING 1 PLANT kElSO BETHANY FOREBAY OAtt \ CHRlSTeNSEN f /»•> toao tamooNeo CANAL BETHANY DAMS. SOUTH BAYPUMPING PLANT MILES BETHANY , RESERVOIR OUTLET FACILITIES' Figure 172. 200 location Map — Clifton Court Foreboy \ PESC40ER0 CHAPTER VIII. CLIFTON COURT FOREBAY General action, the control structure gates can be closed to prevent backflow. Inflows to the Forebay generally Description and Location Clifton Court Forebay is a shallow 28,653-acre-foot reservoir at the head of the California Aqueduct. It a low dam inside the Court Tract. The Forebay is located in the southeast corner of Contra Costa County about 10 miles northwest of the City of Tracy adjacent to Byron Road (Figures 172 and 173). A gated control structure connected to West Canal, a channel of Old River, allows Sacramento-San Joaquin Delta water to enter the Forebay. Water leaves the Forebay through a designed opening in the east levee of the Delta Pumping Plant intake channel just was formed by constructing levees of Clifton north of the Delta Fish Protective Facility. Until the latter connection was made, the intake channel was connected to Italian Slough, located on the west side of Clifton Court Tract, to furnish water for initial operation of the California Aqueduct. A statistical summary of Clifton Court Forebay is shown in Table ' pumping and permits regulation of flows into Delta Pumping Plant. This regulation dampens surges and drawdown which would be caused during peak pumping periods. nels falls Figure 173. View March 1965. Exploration drilling for the Forebay commenced April 13, 1966, the design plans and specifications were completed on July 6, 1967, the contract was all work was is entirely underlain by Quaternary alluvium consisting of deltaic sediments in the central tidal Aerial Preliminary design of Clifton Court Forebay began in Court Tract. The Forebay When the water surface of the Delta chan- below that of the Forebay because of system. Chronology Clifton Court Forebay is located at the southwestern edge of the Sacramento-San Joaquin Delta, where the flat Delta basins merge with the gentle slopes at the base of the Coast Range. These two physiographic regions intersect approximately along the sea-level contour in the southern and western edges of Clifton Clifton Court Forebay provides storage for off-peak ^ an additional benefit of the Forebay reduced canal maintenance costs. Ultimately, the planned Peripheral Canal will supply the Forebay with water, bypassing the Delta channel to be will result in Regional Geology and Seismicity Purpose > proven which awarded on November 27, 1967, and completed on December 17, 1969. 17. ri made during high tides and can be controlled with gates to reduce approach velocities and prevent scour in the adjacent Delta channels. Sediment removal has are — Clifton Court Forebay 201 ' TABLE CLIFTON COURT FOREBAY Type: Zoned 17. Statistical Summary of Clifton Court Foreboy DAM SPILLWAY No earthfiU Top Crest elevation Where exposed to delta waterway Where not exposed to delta waterway Crest width Crest length Lowest ground elevation at dam Lowest foundation elevation spillway necessary of embankment is above all surrounding ground 14 feet 11 feet 20 feet 36,500 feet —10 —16 axis Structural height above foundation feet feet 30 feet Embankment volume 2,440,000 cubic yards Freeboard Above maximum probable delta flood sur- face S feet Above maximum operating 6 feet surface INLET WORKS CLIFTON COURT FOREBAY Maximum operating storage* Minimum operating storage Dead 28,653 acre-feet 13,965 acre-feet not applicable pool storage Maximum probable delta flood surface ele- vation 5 feet —2 feet not applicable pool surface elevation Shoreline, maximum operating elevation* Surface area, maximum operating elevation.. Surface area, minimum operating elevation.. • OUTLET 9 feet Maximum operating surface elevation* Minimum operating surface elevation Dead Control: Concrete structure with five 20-foot-wide by 25-foot - 6inch-high radial gates Design flow 10,300cubic feet per second Design velocity 2 feet per second Intake channel connection: Design flow Design velocity 10,300 cubic feet per second 2. 5 feet per second 8 miles 2,109 acres 2,088 acres Without Peripheral Canal. and northern portions and alluvial fan deposits along the southern and western margins. tirely No known active faults occur at, or adjacent to, Clifton Court Tract. The area is located approximately 21 miles from the nearest known active fault, the The organic blanket ranges in thickthan 1 foot to over 12 feet. In general, the organic soils have low shear strengths and low densities. They include soft organic clays, organic silts, and peat in various stages of decomposition. At first it was thought that the organic soil should be removed, but the existing Clifton Court levees, which had been constructed on this soil at steeper side slopes than planned for the Forebay, showed that the organic soil was usable as a foundation. Reinforcing the same existing levees to serve as forebay embankments was ruled out because the strengths of both levee and foundation were indeterminable. Calaveras fault, and about 45 miles from the San Andreas fault. Seismic considerations similar to those used on the California Aqueduct intake channel and its related structures were applied to the Forebay. Design Dam Description. The dam, which has a maximum height of 30 feet, has two basic compacted zones and is ballasted with uncompacted material (Figure 174). Zone 1 material, which consists of fairly uniform inorganic silty and sandy clays, was placed on the reservoir side of the embankment. The balance of the embankment proper, designated Zone 2, consists of inorganic clays, sands, and silts. Waste materials, such and soft organics, were placed as ballast on the outside of the embankment where needed for stability and were designated Zone 3. Slopes are protected from wave action with soil-cement consisting of nine pounds of cement per cubic foot of soil. as peats Foundation. 202 The dam alignment rests almost en- ic on deltaic sediments which consist of nonorganflood-plain deposits covered by a blanket of organic and peaty ness from soils. less Construction Materials. Embankment materials were excavated from the floor of the Forebay (Figures 175 and 176). Zone 1 material was limited to Borrow Area A, Zone 2 material was selected from excavation throughout the Forebay, and Zone 3 material was excavation that proved to be unsuitable for placement in Zone 2. Sand and sandy silt for use in soil-cement were obtained from an old streambed within the Forebay, and the filter material was obtained from the Pacific Coast Aggregates Tracy. Company located in the City of ' 203 Figure 174. Embankment Sections Law on.? ,wmm? In. Ile/Iunlr/ rum 1mm "dawn,? In: My: ?gmA-A run rm/mv raazL 4 f/ryo/yno Inn 0, zv ?r a Irmpru If no? mun . [In ?Nu/u, yumFur! InIn! rnpu bum ML \r HIM :nn- tr! nu? Inf IN nun": [/ev *5 'ml Ia: L?lall I illrl'll/nln Fry/Flt A. 2 70! wu- n. 4m (try-v.01.? (mum/1 'vcb an? (In -J L-IEGI-I rum?, In" 3 . [luv A rum, noun,? .1 arm." 7'25 DETAIL b- ~u turn ?ft?fl?N P-p roE 6 Mai in[Minn-nun! Ian I :uu 4. _s:cr/0/v Scc/e ,t/u~l ffl?I/O/V :0 ?an - funny mm FFIAIL It! 4 I cum (My! an", "nun?. Ar, no 7 u?z/ (MA {gm/u mu 5:67/0/4/ c-c? (MAIIPML :45 angry/v) slope ~r an 7mm? pawl PI 9 Id A 427?? i/ru. luff I "turnip-Ir I I I [mun-mun: If run [ml rrvr/ Iml I nu nu; I Iii! 2 rtro?r 12/741; dllf?A/Afi run I 1/If? 9w?; 5? mull? ll fl 0! I?Mrlr "Hum? u. 115mm? 414/. P11. In,? In,? 3?41)! mum-4 a M. Slip: /a 34m? 4 In If (lyrical/run r- I Ur ,mu li?lynt nw >In414nal Ol?vua: mu ifd/N Fl?l?H Pfil/l run Una [mm/x Embankment [mh craaz D?l. [?arm rvn? ,vnhehaa 1 {Ar-r: .1 y? 7/ arm/nu rm. 4? - ?0 ,pwanar-r, 44/ 9" 3, ME 9/ 5.4. m; a sicz am 4/ run 4 1- pawn: gCr/o/v r-r 5'01: (ml run a' 4 lint)!" ?gum mm.? ?l fluvi- (u 9 nm rmm? Fife/u! ,c I .42? ?any.? Ann w? A Innaan." (and tour I I .m .. IVFI lmiln?mrn/ . mr .1 >9 0 [mo (MI /l"n:l "men! r? ruin- my. .1. IYPI Fifi, ?f?A/l 5?10ft' 5 90/1 four emu-u own-on noun FORE AV TYPICAL EIBANKMENT SECTIONS 1063687 m. . In? turn I. a Eel-l 1?1- 204 Figure 175. General Plan of Forebuy?Nonh a YPON r/ucr Wm air-'5 1 - wcroou vulva n/pvtp snm? Mahw n- ?l'IIl'ny. I I?ll'Mann 4 - I Fontanv ;2-Jn -ourro~ tau/9r rmcr(lavSAFETY - - V6.11 - WATER "nil-m? onnmuun-m ma?? human mum IUIVN CLIFYOII COUIY NIEIAV GENERAL PLAN uopvu wu- c?vm "nun. -- ICILI 1" ?11-4 205 gure 176. General Plan of Forebay South CLOSURE EMBANKMENT I mum; (rm/m. Hypo/L \f?u?r (Ammunn. r: f? Java." Ala/pl: 1m: Far tutu-?M 4 I - w- 4.1 ?'?'?ouumna ?"nl ?3 -55 u?urm cautv ll-I Ja-ur H?Ma'h! m; AND (mm, m. can up 4? Ir. gram .1 Inn/m, by". t-u'uz'nl? u'm 40' wact (uv' mu tul - afplr?vah-v I ruafvr-l \.rum . [ma 12:5 9 Iceman! ale] 9?LIFTON 00097" A Curran: youpr r?Acr. at u? ?no I-nn'mrloron In." I 4 ll;lml??+ . 4mm? mm.? 3' 3r 34444 14/ I - ?r?w -, arpll-M - lull-n. ?mu, Mud-u ?Ughfun.? nod/w at"; um?, ?nunNoam AN Jomum nIvusmu I CLIFTON count FOREBAV GENERAL PLAN sour? .m an- .. mw,mm, i Jmu - mo. 20?gym?? . - am: at nu an." . maul-?Eng wwh?w lug- 0.. . ,l?m 206 ul llv1~ 5 Ill . "Inapawn..L. in loo.? 1 ?ll-l. .IJ .-I nl-Figure 177. I1I n" Gated Control Structure 1 human I ELAN ?rm [in 2'7 L-I-ZDPIO i? in 'u I at UM um!? ?1 cum MI (IN-I /l 4-1 414m fur?): Flat/om (i - ry-n [I'll 1w? +7 r1] ml! S?Ecr/alv 4-4 I fruit/=1 1' 2? .v I bulb?warn; .n In?. yr. 5 I 4av-mI-n/ ?my, PIN In ?(p-1m or owlJen/g x-I: may 1mmmum-u I I. ,4 .- . 1?11EffrlaN 5?6 u: - wiu- am :Iu. 4-1 .- I 5 . b'lDl- I .I ,n . 9(CI?0ry? 2? 0 I I au-neII r' I II .II I'l("Inn SAFETY In Noe?cry I. WATER al?um autumn cunou counr rouuv CONTROL STRUCTURE GATE STIUCTUIE run AND sacruon ?nuns: Lam? . 1?2" Stability Analysis. The embankment was designed using the Swedish Slip Circle method of analysis employing a seismic force of 0.1 5g applied in the direction that would produce the lowest factor of safety for the condition being analyzed. Soil properties used in the analyses are given in Table 18. Settlement. Probable total consolidation of the embankment foundation was computed be from 1.4 feet to 2.1 feet, including a postconstruction consolidation range of 0.7 to 0.9 of a foot. Specifications required that the compacted embankment be constructed in stages of 4 feet and in several marginal areas in stages of 3 feet. It was required that a period of at least six weeks be allowed to elapse before making any additional placement upon a previous stage. This permitted consolidation to take place and minito under normal design stresses. For the extreme case, a head differential of 12 feet of water, one-third overstress, was allowed. The control structure inlet channel was sized to accommodate 16,000 cubic feet per second (cfs), the maximum tidal flow from West Canal, at an average velocity of 3 feet per second (fps). Riprap was placed in the portions of the earth transi- where the average velocity structure itself was designed flow of 10,300 cfs with resulting and 7 fps through the gate bays, tion The could exceed 3 fps. continuous to pass a between 5 depending on reservoir stage. If a high tide were to coincide with low water in the reservoir during the interim operating period, the full flow of 16,000 cfs could pass through the structure without causing any damage. velocities mized the buildup of pore pressures in the weak foundation material so that it could support the next em- bankment stage. Control Structure To regulate flow into Clifton Court Forebay and to Forebay from the Delta, a gated control structure was required (Figures 177 and 178). It will serve only as emergency control once the Peripheral Canal is completed. This structure consists of five 20isolate the foot-wide by 25.5-foot-high radial gates, housed in a reinforced-concrete gate bay structure. The gate structure includes a 10-foot-wide bridge for vehicular traffic, one set of stoplog slots, and a hoist platform. A riprapped earthen transition extends from both the inlet and outlet of the structure. A 1,000-foot-long riprapped channel with a 300-foot base width connects the control structure to West Canal. A log boom was provided at the channel inlet to discourage boats from entering the area (Figure 178). The control structure was designed for a maximum head differential across the gates of 6 feet of water TABLE 18. Figure 178. Control Structure and Inlet Channel Connection to Canal and Old River — Material Design Parameters Clifton Court Forebay (in background) West The foundation consists of alternating layers of lean clay and sand below the organic and peaty soils. The structure was set on the uppermost layer of sand. To control uplift caused by high water levels in the Delta, it was necessary to excavate a cutoff trench at least foot into the underlying clay strata. This trench and is filled was judged pletely encircles the control structure with compacted impervious material. 1 com- It desirable to construct the embankment adjacent to the structure at an early date to prevent differential settle- ment that could damage the structure. A surcharged was placed over the structure abutments to obtain fill most of the settlement before the structure concrete work was initiated. Pressure from this fill was 2,000 pounds per square foot (psf) greater than the proposed structural load to obtain more rapid consolidation of the embankment foundation. Preconsolidation duration was selected so that when structural excavation began, settlement rates for both the structure and the adjacent embankment foundations would be approximately equal. The five 20-foot-wide gate bays were formed by counterforted abutment walls at each edge of the structure and by reinforced-concrete piers between the bays. The piers were designed as columns with cross-section widths sufficient to block out stoplog slots. The floor slab of the gate structure was designed as a one-way slab on an elastic foundation. The deck slab, which constitutes the hoist and maintenance platform and vehicular bridge, was designed as a simple span which would support hoist equipment and It consists of granular topped with compacted Zone 1 material and a sheet-piling core in the center of the embankment extending from elevation 9 feet, the top of the granular fill, to elevation 23 feet, 8 feet below the channel invert. Existing riprap was removed for 10 feet on each side of the sheet piling. Granular material was fill used to assure speedy placement of a stable fill under water. The closure embankment was placed to elevation 15 feet, 1 foot above the adjoining embankment, to allow for postconstruction consolidation. Piping and Drainage Systems Four pump structures were installed between the of Clifton Court Forebay and the original levee to drain accumulated surface water and seepage (Figure 180). Each structure consists of a vertical, 72-inch, reinforced-concrete pipe placed on a 1-footthick concrete pad; a 24-inch, reinforced-concrete, inlet pipe; a 900-gallon-per-minute centrifugal pump embankment equipped with a 1,200-rpm electric motor; and automatic controls actuated by a metal float. Water is discharged into the Forebay from each pump through an 8-inch steel pipe installed through the embankment. Construction Contract Administration General information about the construction conCourt Forebay is shown in Table 19. tract for Clifton TABLE 19. — Mojor Contract Clifton Court Forebay a H20-S 16-44 bridge load. Studies indicated that for all loading and uplift conditions, the resultant static fall within the middle one-third of the foundaFor earthquake loading, the resultant falls within the middle one-half of the foundation. Five 20-footwide by 25.5-foot-high, tapered, radial gates are supported within the gate bays by means of the hoist cables and trunnion beams. A standby generator was provided for use in case of utility power failure. forces tion. Intake Channel Connection The opening from the Forebay to the Delta Pumping Plant intake channel (Figure 172) was designed to pass 10,300 cfs, the maximum capacity of the plant, at an average velocity of 2.5 fps. The opening is an earthlined channel extending into the Forebay with a level invert at elevation —15.5 feet (U.S. Coast and GeoSurvey sea-level datum of 1929). The invert of the flare section within the Forebay slopes upward at 35:1 and daylights at original ground. The flare section, like the level portion, was designed for a maximum velocity of 2.5 fps. detic Intake Channel Closure The closure embankment (Figure 179) was provided to close permanently the earlier connection of the intake channel to the Delta at Italian Slough and provide a base for the permanent Clifton Court road 208 crossing of the intake channel. 67-45 Specification bid amount Final contract cost Low }i4,421,606 35,904,116 ?2S4,95 3 Total cost-change orders Starting date Completion date.. Prime contractor 12/12/67 12/17/69 Gordon H. Ball Enterprises Dewatering and Drainage Dewatering was the contractor's responsibility and the work was divided into two separate operations: first, maintaining the water surface in all drainage ditches at elevation — 13 feet or lower until filling of the Forebay commenced; and second, dewatering and draining the area where the control structure was to be located to elevation —20 feet. Dewatering to elevation — 1 3 feet was accomplished by cleaning and deepening existing ditches and using existing pumps. Interceptor ditches were constructed to tie in existing ditches. In accordance with specifications, the dewatering operation around the control structure was extended more than 25 feet beyond the outer limits of the control structure. The contractor, in sequence, excavated a 1:1 trench in sandy material to elevation —26 feet, placed a 3-foot blanket of washed concrete sand in the trench, installed pervious concrete pipe 8 inches in diameter, and backfilled with another 3 feet of sand. ?999:3. WW - WI 3805013 AVIBUOJ unoo nouns maul/nu umavor mum: ?annoy 454,0 punt" ,u .4 a; 5,405 i, M: an) 11 ??led l' ?4 )1 {?uu-uunqt 44,154 [till a" 1 "Mn14': m1 04 2n ntru '0 a: 00:14/ :1 ya man; .717: poly Manna 1016won: u: :1 1: wk; :17: A0 pa, nun-.0 mur. 4, 19m.? ?mu/IA? vuloqnyu . Wm, SJJON "u . ~11) !i 95 a ow I cw? :??uvwm wusm ,oll 4 A A ,p . ?Muf?n, '4 7; ?5 wr- 4311:4151qu - 904:7 5. JJ . :?Ka m, ?amt(..- Mummy Eu. ans34:44 4_ 1m 5 (4.1., n, ., ,0 441 717' J0 1538.9 - 1 . . [:04 p.40) mug ?um-uc-a, lullnur. ?3 . luv) x? an . . . "mum494; a 9 g; is 5/4/10 01v a .. [noun myIn.? .- ., u: Iva ?m.13 "mm-z ?humanClosure Embankment Figure 179. 1. .2. w?co - ?dun vac-35 =??Et?ve~5 ~E?cc 209 CLIFTON COURT ROAD PUMP NOCALIFORNIA AOUEDUCT gf 6:0 DELTA FISH PROTECTIVE FACILITY . CL TON COURT FOREBA 210 Figure 180. Drainage System Within a day, the pipe had become completely choked and ceased to function. The piping project was abandoned in favor of open drainage with pumped disposal from two 30-inch-diameter riser pipes. Reservoir Clearing Clearing and grubbing, accomplished throughout the construction period, consisted of removing all trees, stumps, brush, culverts, downed timber, tanks, fences, buildings, privies, cesspools, leaching lines, discarded equipment, and debris. In addition, all existing ditches were backfilled. Grubbing was minimal because the Forebay was built on large parcels of open farmland. Stripping was complicated by several factors. First, the rich soil, deep roots, warm days, and rains caused quick regrowth and second, the weak foundations necessitated the halting of restripping. The contractor was required to pump, clean, and flush all septic tanks; remove all filter material from leaching lines; and dispose of the material outside of the Forebay. Pit privies were dug out and excreta deposits removed and disposed of outside the forebay area. Septic tanks and leach lines were dug out with small backhoes and the debris hauled to approved waste areas. Large-diameter pipes through the old levees were excavated by a dozer, or a grader, and smaller pipes were removed by using a rubber-tired backhoe equipped with a loader bucket. Because of the critical nature of this work, removal of pipe from the old levees was paid for as structural excavation and back- fill. Excavation Excavation was performed under four categories: Forebay, Borrow Area A, structural, and ditch and channel. Forebay. Forebay excavation included material used for Zones 2, 2A, and 3, all of which was utilized in embankments and the various toe details or was spoiled. The contractor had two separate excavation operations: one for stripping surface organic materials which were placed in ballast fills or in waste banks, and another for the underlying material which was placed as Zone 2 and 2A embankment. Forebay stripping excavation equipment consisted of scrapers, jeep tractors pulling scrapers, and doubleengine scrapers. Large dozers were used exclusively as pushers at both the pit and the fill. The other forebay excavation equipment spread consisted of a belt loader drawn by a large dozer. Bottom dumps were loaded from the attached conveyor belt. Because of soft ground, a dozer was needed to assist the bottom dumps in and out of the area. Where conditions were too wet or too soft for the belt loader to operate, the scraper spread was used to complete the required excavation. Borrow Area A. Material from Borrow Area A (Figure 176), the southwest portion of the Forebay, in Zone 1 embankment. It was mostly impervious material and fairly plastic. The contractor was unsuccessful in excavating this material with the belt loader, and the bottom dumps were too heavy for use was used on the wet clay material. Most of Borrow Area A was excavated with a scraper spread. The bulk of structural excavation conremoval of control structure surcharge. Also included was removal of unsuitable material under the control structure surcharge and excavation for Structural. sisted of the keys, cutoff trenches, concrete transitions, piping, drainage pump structures, float wells, and control building footings. Ditch and Channel. Ditch and channel excavawas separated into two general types: that dug with scrapers, and that dug with backhoe or dragline tion equipment. The trenches around the perimeter of the Forebay one of the four pump sumps were excavated with scrapers and blades. These trenches were either vee trenches or vertical wall trenches and usually were constructed in Zone 3 material. Vee trenches were cut with a blade and are similar to a swale. Vertical wall trenches were excavated by using selfloading scrapers (paddle wheels). The existing trenches to be crossed by the new embankment were first cross-sectioned and then excavated until suitable material was reached. This excavation, for the most part, was done with a Gradall which reached down and removed the mud and silt from the bottom until firm material was found. When these excavations were not filled quickly with Zone 1 that drain water to material, fine silt particles carried by ground water tended to accumulate on the bottom of the trench, leaving an undesirable situation necessitating reexcavation. Once these trenches were backfilled with Zone 1 material, they did not cause any further trouble. Handling of Borrow Materials Impervious borrow material (Zone 1) was obtained from Borrow Area A. In place, this material was well above optimum moisture. When exposed to the wind and sun, the surface dried sufficiently to allow the top 18 inches to be taken at about 2% above optimum moisture. By the time it was transported, disked, and rolled, the material usually was at optimum moisture for compaction and little water had to be added at the embankment. Zone 2 material was selected the Forebay outside of Borrow Area A. This from various areas in material was dry and required constant watering and disking to bring the moisture content up to optimum. Because of the availability of Zone 2 material in the northern part of the Forebay, it was used as ballast on the outside of the embankment from Station 229 + 80 to 363+80 (Figure 175) and was designated Zone 2A. Zone 3 material was stripped from Borrow Area A 211 and used as uncompacted ballast outside of the embankment around the southern portion of the Forebay. Zone 4 material plant in Tracy and bankment was supplied from an aggregate was used only in the closure em- section. Riprap required for purposes other than protection of the interior embankment slopes was obtained from department-owned stockpiles at Bethany Reservoir. Processing consisted of primary and secondary blasting and the use of a grizzly. Riprap was loaded with a loader, or wheel loader; a large dozer kept the material worked up into a pile at the pit. Eleven 10-cubicyard dump trucks with special beds were used in the 4'/2-mile haul to the Forebay. Embankment Construction Compacted Material. Zone 1 and Zone 2 materiin the same manner, except that Zone 2 material required constant watering at the embankment. The foundation was not strong enough to support the construction equipment, but it was found als were placed that when an uncompacted 3-foot lift was dozed out onto the foundation, equipment could travel over it. Once the initial uncompacted lift was placed, compaction proceeded smoothly. Material was brought to the fill by either scrapers or bottom dumps and placed in horizontal layers not exceeding 6 inches after compaction. Spreading equipment included a large dozer and a rubber-tired dozer which also pulled a larger hydraulic-operated double disc. Compaction was accomplished by two pieces of equipment on each spread: first, a tractor with an attached dozer blade pulling a sheepsfoot roller; then a large, four-drum, electric power packer weighing 50 tons, the most effective piece of equipment. The power packer could be depended upon to obtain maximum densities in high fill areas. Relative compaction tests were taken in areas where compaction results were questioned, and good results were verified. The required relative compaction was 92%. After completing each stage, the area was sloped to drain. When the 42-day waiting period was over, the embankment was disked and moisture-conditioned prior to placing another stage. Uncompacted Material. Zone 2A and Zone 3 materials were placed in lifts not exceeding 12 inches and scrapers were routed over them. No difficulty was experienced with these placements. Slope Protection. There were two alternatives for slope protection. Alternative A slope protection was riprap material which was to be imported as this large quantity was not available locally. Alternative B slope protection was soil-cement for which sand available in the Forebay could be used as aggregate. No contractor bid on Alternative A because of the higher cost. The soil-cement mixing was done in a batch plant with automatic controls. Spreading was accomplished 212 spreader box continuously fed by dump trucks. of compaction was by two passes with a steel-wheeled roller and no more than five passes with a pneumatic roller. The steel-wheeled roller was by a The method a special side roller that worked off the hydraulic system. It forced the small steel wheel into the side of the soil-cement, allowing it to roll the outer edge to obtain the desired stair-step effect. Curing was done by foggers that were installed on water trucks and worked off a high-pressure system on each truck. The soil-cement slope protection, where subjected to severe wind wave action, has required maintenance since construction. Due to insufficient cement content and/or poor quality aggregate, certain layers of soil-cement have eroded badly, allowing the soil-cement slabs above to break up due to lack of support. Such locations have been repaired by placing riprap over the failure. equipped with Closure Embankment. The closure embankment required removal and disposal of the existing bridge on Clifton Court Road that crossed the intake channel, removal of in-place riprap under the closure embankment, furnishing and placing the various categories of zoned closure embankment material, driving steel sheet piling, and rebuilding the road. Bridge removal and pile driving were done from two large barges. One barge was equipped with a 40ton crane with an 80-foot boom, and the other was equipped with a pile driver. The crane also was used to set and drive the sheet piling, and a clamshell bucket was used to remove the riprap. A gravity drop hammer was used to place the steel sheet piling, and a vulcan, air-driven, single-action hammer was used to drive the sheets. These sheets were easily driven to the planned elevation, and Zone 4 material was then brought in on both sides of the sheet piling. Large amounts of the material had been stockpiled to facilitate the work, and trucks continued to bring material to the stockpiles as the closure was made. After the Zone 4 material had been brought up to grade. Zone 1 embankment was placed. Aggregate base was spread on top, compacted, and oiled with 0.3 of a gallon of SC 250 per square yard. This area was covered with a layer of sand to allow automobile traffic to pass through the work. Riprap was stockpiled on both sides of the closure and was placed as soon as the embankment had been topped out. After the riprap was placed, a guard rail was installed on each side of the road. Construction of the closure embankment and breaching of the existing levee between Clifton Court Forebay and the California Aqueduct intake channel were coordinated. This was done so that water flowing into the California Aqueduct intake channel would not be less than 500 cfs for longer than any 3-day period, nor less than 2,000 cfs for longer than a 15-day period. The work was done at the end of the , irrigation season. Work on the closure began on October 21, 1969 and was completed on October 30. The intake channel embankment was breached on October fornia yard. He supplied the five motor-operated gate hoists complete with gear motor and gear-motor brakes, shoe brakes, gear reducers, limit switches and 31. drum support bases, and wire ropes. It was necessary to modify the bottom seal plate to make it fit the side seal. Bottom seal plate bolts, which were installed earlier, had to be removed. This involved chipping out concrete to a sawed line, drilling in cinch anchors and bolts, and grouting as required by the plans. The gates were tested in the field by both the contractor and the Department. Breaching Levees. The West Canal levee was breached after forebay embankments, control structure, and riprap within the entrance to the Forebay were completed. Levee freeboard within the breached section was removed; then a section in the center of the breach was cut, thus enabling water to flow into the entrance to the control structure. The remainder of the levee was removed by a dragline, and riprap was placed underwater in the new passageway. When this was complete, the Forebay was filled to elevation — 5 feet by allowing water to flow through the control structure at a rate of 500 cfs. In order to breach the embankment between the intake channel and the Forebay, the water in the intake channel was lowered to elevation —5 feet. The breach was excavated to elevation —4.5 feet when the closure embankment cut off the flow from Italian Slough. Vertical openings of 150 square feet were made below elevation —4.5 feet and 700 square feet below elevation —2.0 feet to supply water to the intake channel from the Forebay. The Department controlled the water level in the Forebay to elevation - - 2 feet until the breach was completed. Excavation was done by a dragline, and riprap was placed in the opening underwater. Control Structure Concrete. The contractor used standard, %-inch, exterior-grade plywood to form the inlet and outlet transition walls, but forms were not nailed to the studs in the conventional manner. Plywood was laid loose inside the 2- by 4-inch uprights, and only the vertical walers were nailed. This required closer spacing on the studs and walers but, according to the contractor, took less time and labor. The contractor made good use of new products, such as the various developments in styrofoam and adhesives, which were used to seal the forms against grout leaks at the bottom, joints, and drilled holes. Form work was done in the yard close to the structure. Concrete work on the control structure was begun on January 9, 1969 and completed on June 26, 1969. Water cure for the general concrete work was tried ways. Use of carpets and plain burlap was not satisfactory, but cotton and burlap mats were heavy enough to stay in place. Water was introduced from the top by sprinklers to keep water flowing over in several These mats could be draped over the wall immediately after the forms were stripped and cone holes dry-packed. A curing foreman worked seven days a week. the burlap. Mechanical Installation. The gates were erected by the subcontractor in his Hayward, Cali- in sections drives, couplings, shafting, shaft bearings, Concrete Production The contractor set up a batch plant approximately 700 feet from the control structure. The 1%-cubic-yard batches were discharged into 1 '/^-cubic-yard buckets which were hauled two at a time by truck to the control structures, where a crane hoisted them to the work. Vibration was done by 3-inch electric and pneumatic vibrators. Sixty-cubic-foot-per-minute compressors supplied the air. Twenty-eight-day strengths of the I'/j-inch maximum size aggregate 5 '/-sack mix used in the control structure averaged 4,300 pounds per square inch (psi) ranging from 3,310 to 5,360 psi. The design value for 28 days was 3,000 psi. The 7-day strengths averaged 2,400 psi, ranging from 1,890 to 3,210 psi, and the 91-day strengths averaged 4,980 psi, ranging from 4,130 to 5,770 psi. These figures were based on 38 tests taken from 3,219 cubic yards of concrete between January 8, 1969 and June 26, 1969. Seven tests were made on four other mixes used in the 133 cubic yards of miscellaneous concrete. Test results indicated that the concrete was of satisfactory strength. Electrical Installation Electrical installation at Clifton cluded work Court Forebay in- control structure, control building, and pump structures. Cathodic protection and a standby generator also were provided. Excavation for the conduit between the control house and the control structure was done by a rubber-tired backhoe with a loader bucket. Initially, compaction was obtained by using whacker compactors. Later, the entire length of the trench was compacted by a large air tamper which straddled the trench and pounded the earth with equipment operating much like a pile driver. at the Instrumentation Instrumentation of Clifton Court Forebay was accomplished by using (1) settlement gauges, (2) slope indicators, (3) plastic tubes, and (4) structural monuments. To monitor settlement of the embankment foundation during construction and subsequent operation, 64 settlement gauges (Figure 181) were installed at specified locations. perienced During construction, areas which settlements were watched large ex- for 213 214 Figure 181. Tesi Installa?ans 0 Hum{Imp-nun. r_ .4 - - 23a!? (alumna/"1 nu.? .Iunv:Ni??y ?Al ., Sui-?r4 'olrlhuu mm, . I In?, 1.. [rut pn- ~41 I/lnt-rt . In?: u; . 504/7904. er/rnm: 1 I up I'd/a rot In" I Rlxt?t/vu' Fair A Jr. [MM/wimpy! locohu Ila-n (no ?#4214?an nu! nut/.4 ?dlv . i ?f Van/?1 . .1 It". 9 Na 5:11; "mum-.c'?qmcn' um; A: ?am 5 Man gnaz .rruI II - ?mum: m- 55"" . a 0 - llhocncl ,m .- nun-u..? noun-n av un- cunou coun mun" SETTLEMENT GAGE AND REFERENCE POST 1 1 I at" GALVANIZED non Jet/c. I'nl? L-?nch-I evidence of potential failure and the rate of fill placement was controlled accordingly. Settlement during the period of construction ranged generally between 0.5 to 2.0 feet with a maximum of 2.5 feet at Station 252 + 00 (Figure 175). Following completion of construction and filling of the Forebay in late October 1969, settlement rates became nominal. During a sev- en-month period, from May to December 1970, maximum settlement was 0.07 of a foot. During construction, 8 slope indicators and 83 plastic tubes were installed at seven locations on the forebay side of the embankment to detect and monitor possible horizontal ground movement caused by embankment construction. The plastic tubing was in- stalled at 75-foot centers along two parallel lines at distances of 100 and 180 feet from embankment cen- Although movement was noted in both the slope-indicator pipes and plastic tubes, none was considered indicative of horizontal movement in the foundation. Movements were erratic and frequently reversed direction, indicating the probable influence of adjacent drainage ditches and heavy-equipment operation. All of these instruments are now inundated. Permanent bench marks installed on the control structure have been monitored periodically since July 1969. During the period July 1969 to October 1969, when the structure became operational, settlement of 0.14 of a foot occurred. terline. 215 BIBLIOGRAPHY Department of Water Resources, Specification No. 67-45, "Specifications Bid and Contract for Clifton Court Forebay, State Water Facilities, North San Joaquin Division, Contra Costa County, California", 1967. California 217 SENERAL LOCATION ^ DELTA PUMPING PLANT. DELTA OPERATIONS AND MAINTENANCE CENTER - BETHANY FOREBAY DAM SOUTH BAY- PUMPING PLANT BETHANY RESERVOIR; JETHANY DAMS ^OUTLET FACILITIES tLTAMfi!!!- CALIFORNIA \1 l580> Figure 182. 218 Location Mop — Bethany Dams and Reservoii AQUEDUCT^ — CHAPTER BETHANY DAMS AND RESERVOIR IX. A General Bethany Reservoir pool on the miles down the canal from Plant. The Reservoir is impounded by is California Aqueduct, Delta Pumping five earth The summary of Bethany Dams and Reserpresented in Table 20 and the area-capacity curves are shown on Figure 183. voir Description and Location a 4,804-acre-foot l'/2 statistical is Purpose Bethany Reservoir serves dams. facility is located approximately 10 miles northwest of the City of Tracy in Alameda County. nearest major roads are U. S. Highway 50 and The Interstate 580 (Figure 182). TABLE 20. Statistical Summary as a forebay for South Bay afterbay for Delta Pumping serves as a conveyance facility in this reach of the California Aqueduct and provides water-related recreational opportunities. Pumping Plant and as an Plant. The Reservoir also of Bethany Dams and Reservoir BETHANY DAMS Type: Homogeneous SPILLWAY Type: Ungated broad earthfill Crest elevation Crest width Crest lengtli 250 feet 25 feet 3,940 feet 170 feet 129 feet axis Structural height above foundation Embankment volume 245 feet 100 feet Crest elevation Crest length Maximum Streambed elevation at dam Lowest foundation elevation crest with unlined channel surface elevation INLET 121 feet 1,400,000 cubic yards California Freeboard above spillway crest Freeboard, maximum operating surface Freeboard, maximum probable flood- 5 feet Aqueduct from Delta Pumping Plant lO,300 cubic feet per second Capacity 7 feet 2 feet BETHANY RESERVOIR Maximum operating storage Minimum operating storage Dead pool storage Maximum operating surface elevation Minimum operating surface elevation Dead pool surface elevation Shoreline, maximum operating elevation Surface area, maximum operating elevation.. Surface area, minimum operating elevation __ 6,410 cubic feet per second 1,560 cubic feet per second 248 feet probable flood inflow Peak routed outflow. Maximum OUTLET WORKS 4,804 acre-feet 4,200 acre-feet 150 acre-feet 243 feet 239 feet 190 feet 6 miles 161 acres 150 acres Emergency outlet: Reinforced-concrete conduit beneath Forebay at base of right abutment, valve chamber at midpoint discharge into impact dissipator Dam Diameter: Upstream downstream, 48-inch conduit to manifold of valve steel chamber, 60-inch pressure conduit conduit in a 78-inch concrete horseshoe — 24-inch pipe from manifold to dissipator Intake structure: low-level, uncontrolled — Control: 24-inch butterfly valve at manifold 48-inch butterfly guard valve in valve chamber 121 cubic feet per second Capacity OUTLETS South Bay Pumping Plant Capacity North San Joaquin Division Capacity.. 330 cubic feet per second of California -. Aqueduct 10,000 cubic feet per second 219 SURFACE AREA IN AREA 300 250 200 150 IOO 22c AREA are (RESERVOIR STORAGE IN HUNDREDS OF ACRE-FEET Figure 183. Chronology The five dams were built under two separate con- tracts. A single darn, designated the Forebay Dam, was constructed initially to create a reservoir to supply South Bay Pumping Plant (Figure 184). This initial pool was designated Bethany Forebay. After a few years of operation and with the construction of the California Aqueduct underway, the second contract was awarded for construction of four smaller dams southeast of the Forebay Dam. These four dams al- lowed expansion of the initial reservoir and provided the most economical conveyance facility for this por- tion of the California Aqueduct (Figure 185). The resulting pool is designated Bethany Reservoir. The initial dam designation, Forebay Darn, has been retained; the later dams are referred to as Betha- ny Dams No. 1 through No. 4, or adjacent dams. During the initial operational period of the South Bay Aqueduct (before December 1967), water was pumped into the Forebay from an interim canal join- ing the Delta-Mendota Canal. This interim canal was abandoned upon completion of the reservoir enlarge- ment, and service from the California Aqueduct com- menced. Detailed design of the Forebay Dam was started in 1958, and construction was completed in 196]. Design of the four adjacent dams and expanded reservoir was started in 1965, and construction was completed in 1967. 220 Area-Capacity Curves?Bethany Reservoir Regional Geology and Seismicity Bethany Reservoir is located in an area on the east ?ank of the Altamont anticline of the Diablo Range. Recent alluvium and sedimentary rocks of the Upper Cretaceous Panoche formation are the two geologic units present. Recent alluvium consists of clay and sandy clay with minor lenses of silt, sand, and gravel. The Panoche formation consists of interbedded shales, sandstones, and siltstones with occasional hard, Figure 184. Bethany Forebay and horizontal drains located downstream dam. The plan, profile, and sections of the Forebay Dam are shown on Figure 186. Adjacent dams, 50 to 121 feet in height, are of the same design except for the drainage system. These dams have strip drains comprised of granular materials surrounding perforated drain pipes in place of the Forebay Dam's continuous pervious blanket drain. The plan, profile, and sections of each of the four adjacent dams are shown on Figures 187 through 190. nal sloping from the axis of the Stability Analysis. sections Stability of the embankment was investigated by the Swedish Slip Circle method of analysis. Cases analyzed included full reservoir and critical lower reservoir levels combined with earthquake loading. Earthquake loading was simulated by the application of a horizontal acceleration factor of O.lg in the direction of instability of the mass being analyzed. Settlement. No detailed settlement analysis made. Consolidation practically struction. Figure 185. was indicated, however, that settlement would occur during concamber of 1% of the fill height was pro- all A vided for each of the five dams. Bethany Reservoir calcareous, boulder concretions within the sandstone beds. The strongest earthquakes in the area in historic times are thought to have originated either on the San Andreas, Hayward, or Calaveras fault systems, all of which pass through the San Francisco Bay area. It is doubtful that any of these earthquakes in the project area exceeded an intensity of VII on the Modified Mercalli scale. Design Dams Description. The 119-foot-high Forebay Dam was designed as a homogeneous rolled earthfill with inter- TABLE tests 21. Construction Materials. On the basis of surface examination and auger holes, a knoll adjacent to the right abutment of the Forebay Dam was selected as the primary borrow area for that dam (Figure 191), and another knoll between Dams Nos. 3 and 4 was selected as the borrow area for Dams Nos. 1 through 4. Suitable materials from required excavations also were used in the dams. In the areas above the water table, natural moisture was well below the 15% optimum while, in a few areas where water was encoun11.1 to 28.6%. A tered, moisture ranged from summary of material design parameters is shown in Table 21. Soils were tested for material parameters by the Department of Water Resources. Pervious materials were unavailable on the site and were imported. Material Design Parameters — Bethany Dams 222 Figure 186. Bethany Forebuy Dom?Plan, Pro?le, and Sections xi ?/74 n1 676/ ?lam I i I $0432?53. 3 Nu .139\ zln? Oggi 53. E5 ?1 gg? .Xllill L. tun Ella. Cg IE4 01.: wgng< all >m g: amzsz yr?: >20 mmodozm i Eye?: .rrur: ?v '41; I [ll 0000.:? 223 Figure 187 Dam No. 1?Plan, Pro?le, and Sections (All. Mar re (?mu-4 ?MI-nrv an. mm h, 1 1 1.11m 51 i 9. av pipe . . sonar-er. . . i I - 3"0 5.49 par/m, aw r. not- [hr u! {Ia-r :2 ("Irv/t MW Ml PLAN 0" 9m. nn' .139Sign. ran-bal-l'l-I SECVION l-l ?u/n (510' un_u_ nam\ . 1 ?we ?-14 DIA..A. 0N W00. ?l t. {mu I run (In an? 1.7.7: wuruu \[u-mnu ?mu 1/ ruin/f [rt/471M a; ma! Grand 51w ?quu .nnl u-J min-1 nun/um rm 1 om M. Irwl xv; I lulu ucrmv 0F I lull - 51-00 5* 57-? 015nm? new cram-:7, 5mm,? mmfwaanrmm .1235? I. me an?! Curtmn mil he ?Mayan {mm .9050va mm I AHZs - .- a- ulna-v 01 admin/115mm 5m nwaa no vatairs/ya 5f ml lrv?rrm ("at um! :r we dam SAFETY - - WATER ?awn-a ?mu-Am? nanny?nu IVAYI I?l?ll ran up .mvl/ dcveln; a camp/rum: ~1me a?lr 2: Mr: .. Izruuv on" I AID IEOTIOI. 224 Figure 188. Darn No. 2?Plan, Pro?le, and Sedions 359 00 ounce. w? m-zm. a surroe "mam. /pomn . ~tar 1mm;- mil/u 4.1.. . 0-, 1 yr: 'wnd 1m. Ea run-r"! [nu/Italian IMI bur-M A, ?and rlG?J *1 Guy! MAXIMUM SECTION OF DAM 2 Sun auxiliary Spar! Arc 2' ?wrap u" zone 4 29 /l PLAN 0? DAM 2 Mum an iv]. am I hwy? Ila sca?c 1150' For ae'a-rs 5? 0-9 Esr-maved rounda?an 1mg A uf?d 1m. 9m I Encavafa n: cpprovld rock - 5mm an ha'es \o SECTION Ital. 1? 5216672; rum are no a [In no:\ OIAGEAM 0N 0F 0AM 9) sou; '16 an :50 meI (lumbar . . - 4, ?awmn m- 35W rm" nyma/ r. map. at cup?. 3 ram.? my. 9-: r2 4 Ivan! u: mm. ?Orou? ?ap(fw u- my Pyl?l? 1m am no a run 910 are 1-Draw 1 .107 or .aran .mrunur paw. :wue you my ctr" auton- Inn a nu SAFETY - - Nun?y - - 4 J-?ahnM ?mum .r cur?rt k?gn 1 "me "am ?lam alum-u cl." chum?: IAT- or 1-. w? an: um imam w- and. mum unun nun DAH 2 ?3 . ll . \Ihe .l .8 ..S x! 2.. :2 illi.5 I a: the Elk - 111111111 mar?- :a iris! 2 .L .3. I. .3 :dl d?t?ih. gag: 2 SE23 395? me} a! :3 3.5.5 haw xi. ?2.31. :85. 5.. Pu (as. 1; $12 Rake.? Fe ?2 .13! 3:1 L-s-t ax biotin 3 963? $8;ka .330 ?6 .u m?ug \o . x33 325v.? 8n gilt ?a Ll?: . I SEE: 39b\ 15% Rn 5- :5 an? 330.. mum?- 8-3 8.3 8?rm! Dom No. 3?Plan, Pro?le, and Sections Figure 189. 225 226 Figure 190. Dam No. 4?-Plon, Pro?le, and Sec?om r?C gr dam NW .1 (few 2" _?Iu 11? ?39 any?: In.? Enmuvea to. -. unul?Gf?an.? OF DAM 4 Seq/o '20 Em. 250.: . In.? Iap?? FOP 0N CREST of CAM 0; Hannah-w ?may; Ongmo/ grungy an?; up 45-, u, For drier/1 or Great cap chornagl our?v?nnmavm 0am?. .r :u a? ?nunElev :40 uaq-Allag-co [OI-la Dunn" along a! Cu" ?anon. hale: norm! ?av'n'lmfv?r PROFILE ALONG 69557 OF s'a? Kr-m ids-whoa DAM In ,rwv ?(Finn-I pull rum .- GENEDAL PLAN OF DAM 4 4?9?4 ?0 1 a warm: - .- Nun-I - PROFILI MO IICTIOII I m. L.~unu - r- - 227 BETHANY DAM ix :25" PERMANENT SPILLWAY .. ,1 I, . SPEC. 63-28 TEMPORARY SPEC. 59-22 I Figure 191. I I . I II Iqaruurm/AI23Location of Borrow Areas and Bethany Forebay Dam Site WILLIAM PAW AS BUILT . max-?mu .. .. . .. -.- mm?? rm u?o" - m? ?e-ww DRAWING MODIFIED son BULLETIN 200 Foundation. Abutments of all five dams are in sandstones and shales of the Panoche formation. Foundations in the channel sections are either Panoche formation or alluvial deposits consisting mainly of clay. Panoche formation shales and sandstones are strongly weathered, jointed, and fractured and part easily along bedding planes. Many joints, fractures, and bedding planes were coated heavily with iron and manganese oxides, and a few joints and seams are gypsum-filled. The alluvium is weak and, except at Dam No. 3, does not increase appreciably in strength to the depths penetrated. All organic material was removed. It ranged in depth from less than foot on the abutments to about 8 feet in the channel sections. In addition to this stripping, cutoff trenches were excavated through alluvium into stable rock of the Panoche formation. This rock was susceptible to air slaking when exposed. All foundation areas in this formation were excavated within 1 2 to IS inches of final grades, and final excavation was made just before embankment placement. The foundation excavation plan for Dam No. 3 (Figure 192) is illustrative of all dam foundations. A shear seam extends through the channel portion of the forebay dam foundation; however, there is no evidence of recent geological movement. The right abutment contains a joint system that appears to be the result of shearing stresses produced by regional 1 folding. Instrumentation. were installed in the Four types of instrumentation Forebay Dam (Figure 193): (1) surface settlement points, (2) hydraulic piezometers, (3) a cross-arm settlement unit for measuring differential settlement at different embankment levels, and (4) base-plate installations for measuring foundation settlement. The piezometers are connected to an instrument panel in a well at the downstream toe of the Forebay Dam. Surface settlement points were installed on all adjacent dams, and both Dams Nos. 1 and 3 are instrumented with two porous tube-type piezometers. Outlet Works Forebay Dam. In the first phase of operation, wawas diverted by gravity from the Delta-Mendota Canal, about 2 miles away, through an interim canal to the right abutment toe of the Forebay Dam. It was then pumped into the Forebay through the outlet conter the Reservoir in case of emergency. The outlet works is located on the right abutment. It consists of a low-level intake structure, with trashrack; a 60-inch-diameter, reinforced, cast-in-place, concrete conduit upstream of a valve chamber; and a 48-inch steel pipe installed in a 96-inch, horseshoeshaped, concrete, access conduit between the valve chamber and the downstream portal structure. A 48inch butterfly valve in the valve chamber provides shutoff for dewatering the downstream facilities. Beyond the portal structure, five 24-inch lines branch from the 48-inch steel conduit and extend to the former interim forebay pumping plant. The 48inch steel conduit and the manifold are encased in concrete. These five branch lines were capped when the interim pumping plant was removed from service. A 24-inch, steel pipe blowoff extends from the end of the manifold to a reinforced-concrete energy dissipator in the stream channel. This blowoff is controlled by a 24-inch gate valve. An investor-owned utility company supplies the power to a load center for valve chamber lighting and ventilating and for driving the valve operators. The plan and profile of the outlet works are shown on Figure 194, and the rating curve is shown on Fig- ure 195. Outlet to South Bay Aqueduct. An unlined intake channel at the southwest margin of the Forebay supplies water to South Bay Pumping Plant. Outlet to California Aqueduct. A connecting channel, designed to carry 10,000 cubic feet per second (cfs) at a velocity of 2 feet per second, supplies water to the expanded Bethany Reservoir (Figure 196). The outlet from Bethany Reservoir into the California Aqueduct consists of a check structure located at the southwest edge of the expanded reservoir. Spillway Since the Reservoir was constructed in two phases, also were constructed. The temporary forebay spillway (Figure 197) was constructed under the Bethany Forebay Dam contract at the location where the California Aqueduct later entered the Reservoir. This spillway was replaced by a permanent spillway constructed under the canal embankment two spillways Specification No. 63-28. The permanent spillway consists of a straight, unlined, trapezoidal, earth channel located in a saddle about 200 feet beyond the left abutment of the Fore- The duit. bay Dam. In the second phase of operation, water is delivered by gravity to Bethany Reservoir through the California Aqueduct. The Aqueduct enters the Reservoir crete broad-crested weir located through a topographic saddle about 750 feet to the southwest of the left abutment. The original outlet works of the Forebay Dam will be used only to empty 228 control structure is a reinforced-con- midway along the spillway alignment. The spillway channel is unlined because the need for its operation is extremely unlikely. The maximum probable flood (peak inflow 6,410 cfs) can be accommodated fully by the outlet facilities to the California Aqueduct (capacity 10,000 cfs). 229 Figure 192. Foundation Excavation and Drainage Details?Dom Na. 3 l/?t In hunt-mu tonal/mam 76'00 Aw." .r I In. . n-ma (nay-n? (a nun .lPaw? ?WV/":w?EmMaosEc Std). . . 5T I ("maul ?mmlanon ,InStir/3N A - guymaz ground I <[Mtunltn Ian. I I (an: SECTON 5-8 Scaln j'u (?mic a! yum June- ?on - Is ant/Amy?: Mac/Dy Joplin 0r. .na/ (curd Fa I 9 9 . ran na:'od [plug -4 4 - "an ?my ur-l?nr?lly a! and. al? - Ingmu around Imnr "am-m mum 4pm I In] glv?J f-I' ruin - I (In m. r] fid?fL?/V woman to In! Ito/l _?\Irtm s-Ea/_ Iona; ?1 saw. 13/ l- A I I'lrn . (at A "It[{Inmand launder/M leif (ant (mm: fang/rat g?ound Im- N'ntp?au qull' a? I . I'll lar tum.? .mm nut-u l?nt I'm/r u: 0-, I in man! :In s-ag,??zuw :4 1 I rang-nu Im- ?1 SEC "An nu- nun-u Hum-A ?was! -I room In am mum IITHM akamolo ninouo 5:35? II dauphin ?Misha szwma< I I Ila-x! I ?>amz 35.15 3! I859- in 3123.5: 0. 13-053:- niln! nu :9 82-3339. 3.: 2:31; 3522 .63.. m5 953.. uqu>z< at; nozzmodzo 1.5.3835 pan mnnjozm I-zao-o v" 1 W. v-v NOIIJJS 8-5 Iva/13;: ruvno our 'nuon 'una . AVAWMJS . t) I'd AIVHLII 0 Drona An nmol mm?, 1111 17IO-I on uouvama Lg 1 wow a: Are?: u/ ?vr?sna? a? ?law; -le, [ed .q mama?!" ewe? ,mm play pa Mp." 1'94 ?Mun; ?Jaw?, ?(ya/nu, nq 94pm nun/M; puodu awmwa mama .1?pr ,0 ,1 av a; My 348?? rim/v 7ra0~39 ??hw ,6 I ave?: 0-7 .1, NVIJ . r: a r. uw' I a/rvta?sruo'rT - . 39:39?own/nu I . @)da.nrnull W/Lyto?Figure 197. Temporary Spillway 234 Construction Contract Administration General information about the major contracts for the construction of Bethany Forebay Dam and Betha- ny Dams is shown TABLE 22. in Table 22. — Major Contracts Bethany Forebay and Bethany Dams Bethany Forebay Dam 59-22 Specification Low bid amount Final contract cost Total cost-change orders Starting date Completion date Prime contractor ?877,870 ?876,339 226,456 11/25/59 3/9/61 O.K. Mittry & Sons Dam Bethany Dams 66-17 51,716,650 ?2,057,838 ?87,448 5/10/66 12/13/67 Rivers Construction Co. Inc. Diversion and Care of Stream Streamflow through the Forebay Dam site (Specification No. 59-22) was controlled during construction by a small earth embankment and retention pond ap- proximately 1,300 feet upstream from the Dam site. A drainage ditch was provided around the South Bay Pumping Plant site during excavation of the intake channels and later was converted for permanent hillside drainage and erosion prevention of the channel cut slopes. Diversion facilities were unnecessary for the four Specification No. 66-17. dams constructed under Foundation Material from all dam foundation excavations suitable for use as compacted embankment, riprap, or topsoil was stockpiled for later use. Unsuitable material was wasted in the reservoir area. A total of 64,000 cubic yards was excavated for the foundation of the Forebay Dam and 333,000 cubic yards for the foundation of Dams Nos. 1, 2, 3, and 4 (Figure 198). Figure 198. Bethany Forebay and Excavation for Adjacent Da Figure 199. Foundation Grouting — Bethany Forebay Dam Seepage water accumulated in the middle 100 feet of the cutoff trench of the Forebay Dam. This was controlled by embedding a slotted 2-inch-diameter pipe in a gravel-filled trench and pumping from an 8-inch riser set at the low point. One-inch vent pipes were installed at the one-third points of the 2-inch pipe on each side of the riser. After the embankment was placed 10 feet above the foundation, sand-cement grout was forced into the drain system through the 8-inch riser to force out the remaining water and seal the system. Water was encountered in the vicinity of the interim canal crossing under Dam No. 1 and was controlled by pumping. Grouting A concrete grout cap, 3 feet wide by 3 feet deep, was placed in the foundation of each cutoff trench along the centerline. The trench for the grout cap was excavated mainly with a rotary bucket wheel trencher which worked well in the soft shales and sandstones and usually left a smooth uniform cut. Because the shales tended to air slake severely, the concrete grout cap was placed as soon as possible after trench excavation. Grout nipples were set on 5-foot centers in the grout cap. The split-spacing method was used for drilling and grouting the curtain along the entire length of Bethany Dam (Figure 199) and the adjacent dams. Primarily, holes were drilled and grouted at 40-foot spacing, and secondary holes were set midway between the primary holes. The spacing similarly was "split" twice more, so that the final spacing of the grout curtain holes was 5 feet except on the higher portions of the forebay dam abutments where the spacing was 10 feet. The specification provided for the holes on 10foot spacing to be 50 feet deep and the intermediate holes to be 25 feet deep. Both stage and packer grout methods were used. 235 236 Fi gore 200. Location of Borrow Areas and Adiacem Dams .o-o - z, a I 5 any] #47732: 2 . ?no.4! . I I ?mum .7, ?6 Mu an . I SAFETY Neat-NV mu av ?a unwan- Aal-?w nun-mum on wnu unconcn ammu- a an.? no com-mm my: numu nulnlm- mum: mom nu JOAQUIN aunmv mus GENERAL PLAN non-nu. Inn want: mum; at .ouo- n-u . sur: may a: u- u?w-u an . a. uni nu #T?j w-r?Ng?g-q :2 - During stage grouting, holes were drilled to partial depth, grouted, and then cleaned out by flushing with water before the grout in the hole had set. After the grout in the surrounding rock had set, the hole was drilled an additional interval, stage-grouted, and flushed out again. This process was repeated until the required depth was reached. During packer grouting, the hole was drilled to full depth, and then packers were set at depth in the hole to isolate selected intervals for grouting. Handling of Borrow Materials The borrow materials for all dams were obtained from designated borrow areas, foundation, spillway, and connecting channel excavations (Figures 191 and 200). Where possible, the material was placed directly in embankments being constructed; surplus material was stockpiled for future use. It was unnecessary to go to Borrow Area B under the forebay dam contract because all material was obtained from other areas of surplus. A total of 285,079 cubic yards of excavation in borrow areas plus suitable material from the foundation and spillway excavation yielded 289,712 cubic yards of compacted embankment for the Forebay Dam. A total of 1,037,338 cubic yards of compacted Zone 1 embankment from designated channel excavations and foundation excavations was placed in the four adjacent dams. Impervious borrow areas (Zone 1 material) were moisture-conditioned by sprinkling to near-optimum moisture content prior to excavation. At times during construction of the Forebay Dam, the premoistening operations were poorly executed, delaying and complicating embankment placement and compaction. The processed filter and drain materials (Zones 2 and 3) for all dams were obtained from commercial Figure 201. aggregate sources in the Tracy area. There was enough suitable rock in borrow areas and other areas of required excavation to supply all of the riprap and the riprap bedding (Zone 4). Rock was stockpiled as excavation progressed, then hauled to the dams by 5-cubic-yard, rubber-tired, front-end loaders. Embankment Zone Construction embankment, the bulk of all the dams, was placed by controlling the distribution and gradation of materials throughout the fill to avoid lenses, pockets, streaks, and layers of material differing substan1 from surrounding fill. Embankment materials were spread in successive horizontal layers, not exceeding 6 inches in thickness after compaction. As tially hauling and spreading of the material had a drying an adjustment to the moisture content was made with a water truck, followed immediately by disking for mixing just prior to compaction. The contractor was required to keep the compacted materials adjacent to the abutments 2 to 3 feet higher than the rest of the fill to provide a good seal between effect, the abutment and the Good compaction fill. were obtained when moisture control, rolling of lifts, and rock removal were done properly. Compaction improved as the work progressed. The low densities found early in construction of the Forebay Dam were not considered critical, and it was reasoned that the overburden weight of the upper material would sufficiently consolidate the lowdensity areas. Twelve years after the completion of the Forebay Dam, settlement gauge readings showed a maximum settlement of 5 inches, well within the results anticipated amount. The Forebay Dam during final construction stages is shown on Figure 201. Bethany Forebay Dam Construction 237 overall average in-place dry density for Betha1 was 107.3 pounds per cubic foot the trench was backfilled to subgrade with compacted ny Dams Zone impervious embankment. ranging from 95.2 to 120.4 pcf The average relative compaction was 98%, ranging from 91 to 106%. Zone 2 (filter) material was placed in layers not more than 12 inches thick after compaction, and Zone 3 (drain) material was placed in layers not more than 15 inches thick after compaction. In Dam No. 2, obtaining the proper density of the sloping drain was difficult. A maximum of 4% moisture before compaction was specified. This was increased to 8% before obtaining the required 70% relative density. The increased moisture content was supplied throughout the construction of all four of the adjacent dams. The moisture content for the sloping drain zone was not specified in the forebay dam contract, and the zone was placed without incident. As the Forebay Dam became higher, the drain became longer and placement lagged. Until additional trucks were used, the elevation of the drain zone fell below the other zones. The average relative density for Zone 2 material in the Bethany Dams was 71%. Forty-seven (63%) of the 74 tests taken were above the 70% relative density specified. Zone 3 material was placed with little dif- The outlet works conduit, including 2-foot by 6inch cutoff collars at the construction joints, was monolithically cast in 32- and 33-foot sections. Sixinch, "dumbell", rubber, water stops and '"ch of expansion-joint filler were placed in the construction joints. A 48-inch-inside-diameter steel pipe was placed on concrete saddles spaced at 16 feet inside the 8-footdiameter, walk-in, horseshoe conduit. The (pcf), ficulty. Zone 4 (riprap bedding) material was dumped and spread on prepared surfaces in layers not exceeding 12 inches after compaction. Spillway Excavated material from the temporary forebay spillway, where suitable, was placed in the embank- ment. The remainder was wasted in the reservoir area. This spillway structure site was overexcavated and backfilled to grade with concrete. After the permanent spillway for the extended reservoir was built, the Aqueduct was excavated on the alignment of the temporary forebay spillway. Suitable material from this excavation was used in the aqueduct embankment, while the remainder was spoiled in designated areas. Outlet Works Excavation for the outlet works of the Forebay Dam followed excavation of the dam foundation. Outside the cutoff, alluvial material was removed to sound rock. From the intake structure to the walk-in portal, shotcrete protective coating was applied to prevent slaking; then the trench was backfilled to subgrade with concrete. Downstream of the walk-in structure. '/z Concrete Production Concrete was supplied by a commercial ready-mix plant and was mixed and transported to the placement site in transit mix trucks. The manually operated, 3cubic-yard, batch plant was located 2 miles north of the City of Brentwood on State Highway 4. Transit mix trucks varied in capacity from 5 to 9 cubic yards. The haul distance to the site was about 20 miles, and the average haul time was 45 minutes, with an average unloading time of 15 minutes. Mechanical and Electrical Installations A ventilating fan, operated by a '/^-horsepower motor with an output of 406 cubic feet per minute, was installed in the storage and equipment house. This ventilating equipment was connected to the portal structure by an 8-inch-diameter cast-iron pipe. Air was blown into a 9-inch-diameter aluminum duct through the walk-in conduit and discharged at the valve vault. A 50-amp load center also provides power for the lighting system and the 24-inch valve operator. Reservoir Clearing The reservoir area below elevation 240 feet was cleared of all trees, brush, rubbish, fences, and a timber bridge. Trees were cut off within 1 foot of the ground. Placing Topsoil and Seeding Topsoil placed on the downstream slopes of all selected from the stockpiles that contained dams was the most fertile loam. Ammonium sulfate fertilizer was spread evenly at the rate of 400 pounds per acre, and seed was sown at the rate of 60 pounds per acre. Immediately following seeding, the seeded areas were covered uniformly with layers of straw and anchored by rolling the entire area with a punching-type roller. Embankment Test Installation The instrumentation described earlier in this chap- was observed continuously during construction and now is observed on a scheduled basis. ter 238 i.. Ik. I BIBLIOGRAPHY California Department of Water Resources, Bulletin No. 117-12, "Bethany Reservoir Recreation Plan", December 1970. Development 239 ^esr ^fffv PLEASANTON >4 ^L s:y ^y toy. a AQil DEL VALLE BRANCH DEL VALLE PUMPING PLANT PIPELINE 'DEL VALLE DAM LAKE / DEL VALLE .^c^y ^^cm ^^.m/cr / MILES I Figure 202. 240 Location Mop — Del Voile Dam and Loke Del Voile CHAPTER X. DEL VALLE DAM AND LAKE DEL VALLE Dam. It consists of an inclined, multilevel, reinforcedconcrete, intake structure; a 78-inch-diameter pressure tunnel; a valve vault at the axis of the Dam; and General Description and Location Del Valle Dam is a 235-foot-high zoned embank- The spillway control structure 60-inch-diameter steel pipe inside a 9-foot - 6-inch, horseshoe-shaped, walk-in tunnel beyond the valve a Tient containing 4,150,000 cubic yards of material. an 84-foot-diameter, ingated, glory-hole intake located 1,600 feet southeast )f the Dam beyond the right abutment. The spillway intake discharges into a 30-foot-diameter vertical shaft oined by an elbow transition to a 28-foot-diameter, ,893-foot-long, nearly horizontal tunnel. An 18-footiiameter, flood control, outlet works tunnel dis:harges into the spillway tunnel at the elbow. Highis elbow control the low through the flood control outlet. A smaller conervation outlet is located between the spillway and )ressure slide gates located at the Figure 203. Aerial — View vault. Lake Del Valle has a capacity of 77,106 acre-feet, a surface area of 1,060 acres, and a 16-mile shoreline. The Dam and Lake are located in Arroyo Del Valle, south of Livermore Valley, approximately 4 miles from the City of Livermore in Alameda County. Arroyo Road, a paved city street and county road, affords just from Livermore to the Dam site. The nearest major roads are U. S. Highway 50 (also Interstate 580) and State Highway 84 (Figures 202 and 203). access Del Valle Dam and Lake Del Valle 241 A Del summary of Del V^alle Dam and Lake shown in Table 23, and the area-capacity shown on Figure 204. statistical \'alle is curves are The 320-foot-deep Del \'alle Shaft, which served as access to the Hetch Hetchy Aqueduct tunnel, was plugged with a combination of concrete plugs and fill material under Specification No. 67-55. The Shaft and its access were submerged by Lake Del Valle. The Shaft had been used for access during construction of the tunnel and was considered for the same purpose for construction of a future parallel tunnel. With the existence of Lake Del Valle, this future construction are pending. is impounded by the Dam and convenience of downstream water users. The Department of Water Resources has received payment for these conservation benefits from the water agencies involved. Local storm runoff later released at the Chronology The State started preliminary surveys at the site in 1957 and final design in 1964. Dam construction was begun in March 1966 and completed in 1968. Regional Geology and Seismicity The Dam and scheme was abandoned. Mountain Range, Purpose The purposes of the project are to provide regulatory storage for the South Bay Aqueduct (30,000 acre-feet), flood control for Alameda Creek (38,000acre-foot reservation), conservation of storm runoff, and wildlife enhancement. of Engineers has made payments of approximately $4,900,000 toward the conoperation and struction and the capitalized maintenance costs of the flood control features of the Dam and reservoir. Possible additional appropriations recreation, The U. and S. fish Army Corps TABLE 23. Statistical Summary reservoir are located in the Diablo a part of the Coast Ranges. Geologic formations in the area consist mainly of sedimentary rocks folded into northwest-trending anticlines and The oldest rocks in the area, Jurassic graywackies, cherts, shales, and serpentines of the Franciscan group, crop out in an extensive area south of the synclines. reservoir. Younger Cretaceous sandstones and shales of the Panoche formation are present at the Dam site and extend for several miles west where the Panoche formation is in fault contact with Franciscan rock along the Williams fault. Above the right abutment of the Dam, soft sandstones and siltstones of the Miocene of Del Valle Dom and Lake Del Valle DEL VALLE DAM Type: Zoned SPILLWAY Type: Glory hole with concrete-lined tunnel and earthfill Crest elevation Crest width Crest length.... _.. 773 feet 25 feet 880 feet 745 264 84 28 Crest elevation Crestlength Crest diameter Tunnel diameter Streambed elevation at dam axis Lowest foundation elevation. Structural height above foundation Embankment volume 550 feet 538 feet 235 feet 4,150,000 cubic yards Maximum 28 feet 69.8 feet 8.4 feet feet feet 764.6 feet surface elevation Standard project flood inflow Freeboard above spillway crest Freeboard, maximum operating surface Freeboard, maximum probable fiood feet 64,000 cubic feet per second 44,200 cubic feet per second probable flood inflow Peak routed outflow Maximum stilling basin feet 23,500 cubic feet per second 7,500 cubic feet per second Routed outflow Water surface elevation 749 7 feet . INLET-OUTLET Del Valle Pumping Plant 120 cubic feet per second Capacity, in or out OUTLET WORKS LAKE DEL VALLE Storage at spillway crest elevation Maximum conservation storage Storage at flood control pool Minimum conservation storage Dead pool storage _ Maximum conservation surface elevation Surface elevation of flood control pool Minimum conservation surface elevation Dead pool surface elevation Shoreline, spillway crest elevation Surface area, spillway crest elevation. maximum Surface area, 703.2 feet 702 feet 638 feet 609 feet 16 miles 1,060 acres 708 acres minimum Surface area, 242 9,863 acre-feet 3,317 acre-feet conservation eleva- tion tion 77,106 acre-feet 40,000 acre-feet 39,000 acre-feet _ __ conservation eleva- 285 acres Conservation: Lined tunnel under right abutment, valve chamber upstream of valve chamber, 78-inch-diameter presat midpoint downstream, 60-inch steel conduit in a 144-inch consure section intake, five-level inclined structure with crete horseshoe tunnel — — — — 42-inch shutoff butterfly valves downstream control, 42-inch discharge into spillway stilling fixed-cone dispersion valve 66-inch butterfly guard valve in valve chamber basin — — 400 cubic Capacity feet per second Flood control: 18-foot-diameter lined tunnel under right abutmenttransition to 28-foot-diameter spillintake, bell-mouth entrance way tunnel control in transition by two pairs of 6-foot-wide by — 7-foot - — 6-inch-high, high-pressure, slide gates in tandem Capacity with surface elevation at spillway crest 7,000 cubic feet per second AREA 1200 CAPACITY Figure 204. unconformably upon the Overlying the Cierbo formation are the Plio-Pleistocene Livermore gravels which extend for about 5 miles northeast of the Dam. formation rest Panoche sandstones and 'Cierbo Del Valle Dam shales. near seismically active regions in active fault zones within 30 miles of the Dam: Calaveras (8 miles), HayCalifornia. ward is There are three major (12 miles), and San Andreas (30 miles). Design Dam Description. I The Dam is a rolled earthfill struc- impervious core, granular ihells, and random stability zones upstream and Hownstream. The plan of Del Valle Dam is shown on ngure 205. Internal embankment drainage is provided by an nclined drain downstream of the impervious core and )lanket drains on the downstream abutments which onnect to a drain in the stream channel. Protective liters are provided between the core and downsteam nclined drain, between the core and upstream shell, rnd between the channel and abutment foundations ture consisting of a central I ]nd drains (Figure 206). , Stability Analysis. 'ection Selection of the preliminary was based on geologic investigations, availabil- and characteristics of materials, known characteristics of foundation materials, and seismic coniderations. After preliminary design was completed, lore extensive drilling and testing for final design jCvealed poorer foundation conditions and strengths lian had been anticipated during preliminary designs. I^s a result, the embankment slopes were flattened and cy IN ACRES 800 1000 IN 1000 ACRE- FT. Area-Capacity Curves stability sections of random fill were added upstream and downstream. Stability of embankment sections was analyzed by the Swedish Slip Circle and sliding wedge methods of analysis. Adequate factors of safety were calculated for the final embankment sections under all cases of loading. These cases of loading included full reservoir and other critical reservoir levels along with earthquake loads. Earthquake loading involved a horizontal force equal to the weight of the soil mass being analyzed, multiplied by an earthquake acceleration factor. Because of the close proximity of major faults and than desirable foundation conditions, the Department's Earth Dams Consulting Board recommended (1) the use of an earthquake acceleration of 0.1 Sg, (2) conservative embankment and cut slopes, (3) wide impervious embankment sections, and (4) freeboard design to include consideration of landslides and less seiches. Settlement. Measurements of settlement in prototype dams of impervious material indicated that most of the settlement occurs during fill placement. A nominal camber of 1% of the fill height was provided to allow for postconstruction settlement. Foundation. The Dam is founded upon sandstones and shales of the Panoche formation. Geologic structure is complex owing to faulting and folding. Most of the shears or faults are small but, in the right side of the channel, there was a shear large enough that soft sheared material was required to be removed to prevent seepage under the core along the shear zone. Beds in the left abutment either are overturned 243 244 Figure 205. General Plan of Dam Ural. more? my: parking arl? w, 1 M1 on ?ue. mu. qu low ((510 soicon! ma rum v" an lean Mm". am? mm Jan:- ?A?au tn 00/ wt. Iranth Imrmq Cam tun-n? .negravel utm?o?? N. . mm 0' "room 4 Am re a. rum" 0, A "mm Cami, XXV [a I . a?cg??w 1 . 53.ma: gum: mmnu Lumr of (any! g" clean/v? I . I I D??MAzqs In? I ., mmhan amrernfm on, I /[1uhnq I . Hmong-d ., -. DEL VALLE PUMPING PLANT Abl?mm Data A Lounou? n, I so" nun sla' 2 ml: 230? 300 5 Ir not: 202' 0 3r mu a' 3 ar- Izua ad rum-mu .1 mm c?m u?n- null mu. n. rm (mm: own now onNan-y - WATEI lIle Cm noun-m or yum yum:- 1 ?mama. AWING MODIFIED DEL on AND FOR BULLETIN 200 GENERAL PLAN 1 anon? nu mm m? Wks-i SNOILOBS Hz pun: "i mu?; Iv nun-m ,wwnro at: ,9 am, yn?aa yam; awn! ,2 1' nu, 140.111ch 1 4m, I I ?e no; 7'77 wan/WW" w/ y) no,? em) In nutauqf ,a m, ?nal/944i- w, pm?: ,nwmo "moo: .Io 7, my- qung new,? r11 ?01: luv 1- ?In: I . ~24 NVCI 130 3193 11,77 Do! i '4 nanonu an? no manna-nu mun; _Io nun-nau- nu aw Amm? 1aw5-1? 5 Wan-Au. _7 ?If 4 9" auvm-M'-mavs \my.? "Mimi?; or?: Jaw g- a 9rIva/133: Ira.w;.~ . mam" Mom?, 2: cu a. or; we wax :an(1. Ola/.1 u/w'5g ?'mz "war-w mu"1mmmm? Ill/W757 7mm5?5 .14, ?mus mamno; (.6 naawm 2 RV Nous]? ;..pqua ?1.4 .nmg 1.9 ?99 '0 . . ?you than?, aw ?ier unuoup I u/w (M19 tamed I 9.9 4.1 nun}: w; How?! a vw a no, live: woe-v m" '47 (?ii-wld/ :4er?Mun, lid/[Ids :3 was 4 4:57? 1115;? 909 .3 azgwn 1r mum 1:333 1? 3 I Uta-Kanaawow-w ?(mu-1r) I: I am, Mam "who ?Fa: ?Cf,nwav . away a, MN .901. I IDIUDJIIW um: .0 1~3w1r331 J/voz 7mm] I wraay/ .75 a a f'n? ?'01 5w .ul up 3 gm,? manna-man? 9 "5 3? 6 A nun; an; mm, ,9 9.4, um, um, I'll/0W mum no awn-am: wanna?; >140] In?: mam?: u, mm mum, um, 1-day mug k. . ,2 up, r? 1 514/; ?yawn; 4 a i A oun]_ 245 or steeply dipping into the abutment. Beds in the right abutment dip from 34 to 63 degress into the abutment. Sandstones become increasingly abundant in the upper right abutment, and many of the sandstone beds have open cracks. The lower flank of both abutments had considerable volumes of terrace material and slopewash that were unsuitable for foundation. Foundation excavation involved removal of weathered or otherwise weak materials from the abutments, removal of the stream gravels and terrace materials, and clean-out of soft materials from the shear zone described above. The excavation under the core was specified to be about 3 feet deeper than that for the remaining foundation so as to expose less permeable material. A grout curtain, consisting of two rows of holes, was provided at the centerline of the core contact. The grout holes were spaced at 5-foot intervals and were up to 100 feet in depth. Blanket grouting of shallow holes on a 10-foot grid was required in areas where weak permeable material was identified beneath the core. Construction Materials. Construction materials Dam were obtained from various sources. Material design parameters for these materials, as determined by soils testing, are presented in Table 24. Zone lA, the impervious core, consists of clayey soils of the Livermore formation obtained from a location on the north arroyo slope upstream from the Dam. Zone IB flanks Zone lA on each side and was obtained from an alluvial terrace located between the aforementioned borrow area and the stream channel. Zones 2A, 2B, and 3 were composed of streambed gravels excavated as far as 5 miles upstream of the Dam. Zone 2A is the processed transition between the core and drain. Zone 2B is the processed gravel drain, and Zone 3 is pit-run gravels forming the embankfor the ment shells. Zone 4 is a random material from manda- tory excavations. Instrumentation. Dam consists of 3 1 Instrumentation at Del Valle piezometers, 8 Carlson pore-pres- sure cells, 9 porous-tube piezometers, ^ 37 surface monuments, and 8 slope indicators. This instrumentation was designed to monitor pore pressures, settlements, and horizontal movements (Figure 207). Conservation Outlet Works The conservation outlet works (Figure 208) to release natural streamflows in is used Arroyo Del Valle and convey regulated inflow and outflow of South Bay Aqueduct water between Del Valle Pumping Plant and the reservoir. During construction of the Dam, the conservation outlet tunnel was used to divert natural streamflows around the Dam. After construction, the diversion intake was plugged with concrete from its inlet to the elbow at the base of the inclined intake. The conservation outlet works consists of a mul- tilevel, inclined, reinforced-concrete, intake structure on the right abutment; an upstream reach of 78-inch- diameter, concrete-lined, pressure tunnel; a valve vault near the axis of the Dam; and a 60-inch-diameter steel pipe inside a 1 14-inch-diameter, horseshoeshaped, walk-in tunnel extending from the valve vault to a control structure near the left wall of the spillway stilling basin. The inclined intake structure (Figure 209) consists of a 7-foot-square reinforced-concrete conduit from elevation 710 feet to elevation 600 feet; a transition to a 78-inch-diameter circular conduit; and an elbow and thrust block near streambed level. To provide for selective level releases for water quality control, 42-inchdiameter butterfly valves and trashracks were installed at elevations 690, 670, 650, 630, and 620 feet. The tunnel transitions from a 78-inch diameter to a 60-inch diameter with a steel liner immediately upstream of the valve chamber. The valve vault contains a 60-inch butterfly valve shutoff, two air-vacuum valves, and a mechanical-type coupling for ease in assembly of the for emergency valves and steel pipeline. Dimensions of the valve vault are sufficient to install, operate, and remove the butterfly valve and operating mechanism. Irllt I?l/ ?unumln'\ 44 . ru- 19 ?r 9.14 r" '11 ?yuan swr. . alum: ?we wry/"nu 5 1?11 {1911? (I'll? mum, u'wmmr 1w, - "on, 87401 ?1 En v! [Ivy uw (Hr-nut nun? - L7. 571 (4?55 5:11 Figure 207. 1 .731 NI N014 71 7:5 ?uuruw (r and 1. (nun-m ?4?0 I "Hum?! "Mn 0-, r- Inna/u If m, mm ?nu/4m ,u bur: um: a 1 Location of Embankment Instrumentation ?mum- zsaswp A. . um. ?lul'l'f'vn .?wuum- v? . .umm mun?, .4, W, ., x5) aria? "Wm-u. . :1 tl??o'vnl or40.! :09ull'l?li?l mu: n~ run] 'um an!? a. (w ruurfmno aunv :1 m. muhio uunm rum a um: . (mm, x. n, a an.? mun." ?m Irma} nun-w. 5v'0rl pan! an: an - nummovwam anon-cu ?Hum?, .itr'un} sun uvu nmmu :ovm uv mum: on. VALLE omsnou a 1- DEL VALLE DAM RESERVOIR .. INSTRUMENTATION PLAN 4. um I, rur AND SECTIONS PLAN a . 7.4.7.1 .4 . . m. Ma Vpan Wags/~21; 247 248 Figure 208. Conservation Outlet Works?Plan, Pro?le, and Sec?ons 44 a '5 '1 a; 25\\ 9M Mum"! was: read rl 1.7; - Atu'rr'v :n ?ne. 5r . 65' .g/u -42. v< 'or?zrr?u nun.? 150'?: am- p'pl m- Vr-ua' 9 tn 5-, 1'0065nun Pa-la' ?vr-Iv?l?v?g 7 5 spagury sgr?r'ozg AA M, 51511 - 50 . In." .59? En 4-47.4.4 slut-rah? Qu? Wart! pnqus? :rra? 5? um 7 Inna .. pm l'glagjo: :relm,ppohi ?an. wamy Udttp 5 '5 na-m ?0 Ian: 2 5' mm, "we? I: IV can: a. -.., "d se.r g? no. 59 To wan/i I?ll/L 7 We a" an, au-fv?li U?lv??dr'?ing 6-4810-3 ground "war/:4 Cu! 4,4, [9Bra-git . . . .. 1nan-w 1: r1,? . 99.um: ?cu. A ms . "pm ,v p.45 on no, 64-. 2 5.9. p-nyl ,n run at .: 5r; 5/ It: Fatla era." . my! 4/ (lieu! hall: M?a'h ?my 4? - a Wr'rd . int-m'y Add! . .. ca." lichen Synw?ld cu? 5-41 5'4 cot-r ":han u! 5 1547/. A rt: A ?9 any-1'" v'uuvwv lvqufnew? a. aha-a an 0-D - Val 'a scre ?an a! or Grin-Hag! 5 E?era' an; nun .-. . rra'vw- ,r u. . "1.1 5 cu :o-u-ns .a u: a poo-aw.u-nubail ,Ivyn? 10.1715 7 c, r, o/ a. [Er unlv' "Afr-var s; v. I .4 0.5 150:765 Hm - no". v. . I'r4('p" J?u? lr?"or um so'o vr Inpw") cw aw ?nv n- .. Nuns-y a WATER mu .7 n- scum-um or warm know-cu unoc- or nIm-u no In" In" mm uv Joanna KL Dunstan DEL VALLE on: no usznvom CONSERVATION OUTLET WORKS pun. PROFILE AND szcnons an .- ?nmn. 1/ A ?if-Pay Figure 209. Inclined lnfake Sfrucfure 249 sum; sun-4: . ?1 4 r15)?: I .rr Lug 5 12-Jpar- n9 17095:- In?; . p. I an (hgnqey rum . 4::lance 0/ . .I than?hvv Va 2 Sea 0 ?55427 5 DE MIL A :hombwl w? Bar. Bar: .IALVE A I I 2 -I- . SECTION 5-: am. 1 -I- a, 9 ,mmd 5-. Ira/um? :v'lranl 6' {UsP?tJl Ba-Al? I [Irv ?a 7.- (V .2 scorn/9 ?mm hill? 9:25,: um; ":49 ?Iang 4 BacufuI/JS) . EIFPDIV ?awn.gm Jacusw I2: 7? fun/Ill ta, rm?: ala:l ?4 r-swcm,\ :m an I: 5 JAIN an ll of an 5.7 75 SECTIONAL NON 0F 54-an [a 75 View-4 SECUON 6-6 ralvv n. TLargdudW?a u?c s?iiml Bel/am V'ransyirat Warp. IranrIaI .vurraz. I I . 1L Mia 55/ 0:7: 3..an- -I.5 7y, in 103 97 c.1740 ?new; rap Jur?aeu Irina. - \K?cwzular I5 .quau . 0.9 fungi/33 :3 {tawny} ??lm 3 >ongn A -L on]: no?! .7 r. .. Il'd'z fI'cs around or! as n5. ya sums?, 539 5605 D: J?quu'ntg tang 1.14 yuI .n pom/Ian 0/4 maumum lpacl?q 1-: Lung I a un-Imgmua V. :5 7 8,0 . pm [E-u no ,r In: 4 $ymmolryral abau! Ila 71? ?roM 5? lad/a .naa '3 Y-al [Vi 3.111%: vain-go. a I 0 "um - "urn/w): . .4 VJ 7 A "re\Iz-rnm 5mm} 1:15" ?k?l ?3 INTAKE SIPUCVLPE SECTIONS scar?when or: . 1 n. n-v?vitemu ?I_l I no .. nun; SAFETY - Noam-y - WATER "mam N. um um: tau-Ammo! Inouncn mm- a- no eon-m sun nun. "Wm scum uv mm" DEL VALLE BMW DEL VALLE mu AND nesenvom CONSERVATION OUTLET WORKS INTAKE STIUCTUIE CONCRETE AND asluroncsusn DETAILS Tla? (5- are 5:51: Ina?ou- The walk-in conduit is a concrete-lined, 1 14-inchdiameter, horseshoe-shaped section with a concrete walkway and concrete pipe supports. This walkway provides room for removal of the emergency shutoff butterfly valve. Peripheral drain holes are placed between Stations 15+45 and 19 + 65 (Figure 209) at 30foot spacing to relieve the external hydrostatic pressure. A sump and sump pump were installed at the downstream end to remove seepage entering the walk-in conduit. A ventilation system was provided, consisting of a fan near the downstream control structure and an air duct running from the fan to the valve vault. structure was constructed left wall of the spillway stilling basin. It consists of a wye branch and thrust block, a 60-inch by 42-inch reducer, and a 42-inch fixed-cone dispersion valve. The valve allows the flow to discharge into a 10-foot by 9-foot chamber which confines the spray and directs the flow into the stilling basin. A control house was constructed above the valve to provide room for (1) valve operating equipment, (2) sump pump operating equipment, and (3) walk-in tunnel ventilating fan. The conservation outlet works was designed to (1) release 400 cubic feet per second (cfs) at the minimum conservation pool, water surface elevation 638 feet, and (2) to pass a flow of 120 cfs between the reservoir The downstream control as an integral part of the and Del Valle Pumping Plant. To reduce pumping water from the South Bay Aqueduct can be discharged by gravity through the branch pipeline into the downstream end of the outlet and into Arroyo cost, project Del Valle to replace natural flow which is being stored in the reservoir. The 42-inch butterfly valves in the sloping intake were designed to operate either fully open or fully closed, and the 60-inch butterfly valve in the vault beneath the dam crest remains open except in an emergency. Releases to the stream are controlled by the 42-inch fixed-cone dispersion valve at the downstream end. Flow between the reservoir and Pumping Plant is controlled in the plant. The rating curve for the conservation outlet works is shown on Figure 210. The sloping intake may be dewatered for inspection and was designed for this condition with an external water load imposed by a reservoir water surface at elevation 710 feet. The thrust block was designed to spread the load of the intake structure at the base of the structure near streambed level. Maximum allowable load on the foundation was 4,000 pounds per square foot. Trashracks are removable and were designed for yield stress at a differential head of more than 20 feet of water. Steel bulkheads were provided to allow closure of the openings should repair of the butterfly valves be necessary. The bulkheads were designed to resist the water load with the reservoir at elevation 710 feet. The pressure tunnel was designed to resist the full reservoir head both internally and externally (applied individually) assuming no support from the surrounding rock. The valve vault was designed for an external pressure of a full reservoir. The walk-in tunnel from the valve vault to the tunnel portal was designed to resist the external water pressure, which was assumed to vary linearly from 68 pounds per square I ! FLOW-IOOO Figure 210. Jt * C.F.S. Conservation Outlet Works Rating Curve 2S0 JM^ inch (psi) at the valve vault to psi at the downstream control structure. Rock loads from the tunnel roof u ere assumed to be resisted by the support installed during construction and were not added to the load on The walk-in conduit from the downsteam tunnel portal to the control structure was designed to support the load of the pervious backfill assuming the vertical load is equivalent to the weight of the overburden and the lateral load is one-third the concrete \ sections. ertical load. The outlet control structure contains the welded wye, embedded in concrete, which connects to the discharge valve and connects the outlet works \\ith the Del \'alle Branch Pipeline and Pumping Plant. Retaining walls on each side of the control structure were designed as cantilever walls. The wall on the left side contains the fill on top of the structure, while the wall on the right side forms the stilling basin steel wall. The 60-inch-diameter steel pipe and branches were from steel plate which has a minimum yield strength of 30,000 psi and an allowable stress of 15,000 psi. Saddle supports are spaced at 7-foot centers to eliminate the necessity of stiffener rings on the steel pipe. An expansion joint was placed near the midpoint of the pipe alignment to permit expansion and contraction of the steel pipe due to a change in temperature of up to 30 degrees Fahrenheit. fabricated Flood Control Outlet Works The flood control outlet works is located in the right abutment and connects with the spillway tunnel ( Figure 2 11 ) . It consists of a reinforced-concrete trash frame, a bell-mouth entrance, an 18-foot-diameter tunnel 216 feet long, and a junction structure with a 28foot-diameter spillway tunnel. A concrete plug in the junction structure contains a transition to two sluiceways for the purpose of making flood control releases. Each sluiceway has two 72-inch by 90-inch, high-pres- tandem for regulation and emergency shutoff. These sluiceways discharge through a 10-foot by 12-foot conduit directly into the spillway tunnel. A gate chamber housing the hydraulic operators was provided above the sluiceways. Access to the gate chamber is by a stairway in a 9-foot-diameter, sure, slide gates in : I jconcrete-lined, vertical shaft from the spillway over- parking area to a 9-foot-diameter, concrete-lined, access tunnel which slopes at 0.5% to the gate chamber. The control house over the vertical shaft contains electrical panels, ventilation equipment, and a standby engine-generator for emergency operation of the outlet works. The flood control outlet works was designed to release up to 4,400 cfs with the reservoir surface at elevation 702 feet. To provide for emergency reservoir drawdown, the design discharge is 7,000 cfs with the reservoir water surface at the spillway crest, elevation 745 feet. The 4,400-cfs flow corresponds to the capacity of Arroyo Del Valle below the Dam, and the 7,000cfs flow can be carried with minor damage. The intake llook trash frame was designed so that the velocity through the net area would not exceed 5 feet per second for a flow of 7,000 cfs. Except for a case of extreme emer- gency, the slide gates will not be operated at more than open. The intake structure was placed directly on Zone 3 fill rather than on existing rock formations to minimize excavation into the hillside. Two expansion joints were provided in the conduit between the tunnel portal and the intake structure to allow for differential settlement between the intake structure and the tunnel. The trash frame was designed for a yield stress 90% at 20 feet of differential head. The 18-foot-diameter, reinforced-concrete, tunnel from the stoplog slot in the intake structure to approximately 50 feet downstream of the tunnel portal was designed to support 30 feet of overburden, and lining the reinforcement in the concrete lining is sufficient to resist the full reservoir head. The flood control tunnel and spillway junction was designed to withstand the internal pressure of full reservoir head, assuming no support from the surrounding rock. The gate chamber was designed for full hydrostatic head, with normal allowable stresses for water at the lip of the spillway, elevation 745 feet, and no more than one-third overstress for water at the spillway design flood elevation of 765 feet. Allowance was made in the gate chamber dimensions to give sufficient clearance for installation, operation, and removal of slide-gate bonnets, hydraulic operators, and The access tunnel and shaft were designed support 30 feet of highly fractured overburden, and the concrete lining was designed for full hydrostatic head due to a water surface elevation of 765 feet. gate leaves. to Spillway Description. The first type of spillway investigated was an open chute on the left abutment. This alternative was abandoned because of an extensive shear zone that made the location undesirable for a spillway structure. Both side-channel and glory-hole spillways were considered for the right abutment, but these also were abandoned because of the high cuts that would be necessary. A failure of the cut slope could cause rock to slide into the intake structure and render the spill- way inoperable. The design selected was a glory-hole spillway located on a knob 1,600 feet southeast of the Dam. At this location, cut-slope heights were minimized. The spillway intake structure was located 50 feet from the base of the cut slope at its nearest point (Figure 211) in order to provide a space to catch small slides should they occur. The unlined approach apron is on a relatively flat plane at elevation 738 feet and is sloped at 5% in two directions for drainage. The inlet consists of an 84-foot-diameter ungated crest at elevation 745 feet. Antivortex vanes are placed at the one-third points on the circumference. A log boom prevents large debris from entering the glory-hole spillway in- 251 252 Figure 211. General Plan of Flood Control Outlet Works Cwervovmn rowan u. u. no?, '9 bluinrwhon aul/rl ~19; .1 - EMOa?-erl? llml?l I - - M?Nthm cu6?3 55: am]. at A 1. a .- 444; - a, E. a an?! a D4. Aanl rum - Ham I'-sa' omu/ iwwt we ,lnac adep?ll A .9- -y.L tuna Mad) I (lint Ax ?I'll (um-mu Inn-I of animu- A I era/o run"! 0 .5 wear/117) -Urrq.?nl 1p 35: a Top :1wa! ?Wait-4+? 350 a in? nu: I .1.9 m: Cu! rut m-or cw.? .u ?mm thamw :waru 7) Irma/9r 5.7014 mun)? punt awn may?), 4 1 fl ?34/596; will? WWII MI t/J I luv: "Lg r? u: 4 ray-wkown,? mum 605/196! a4 ?1 -'aa Ql N075: I A org-ohm: an Inn. at? r- a "an me urm Ann non: a. moon nu a; vim lMM?Mlnl Asian9090.6 .r :rnr IV 15 ?or nu: MM Jzal' I'-aoPLAN All) take. A transition connects the ogee crest to a 30-footdiameter shaft at elevation 697.60 feet, which extends to an elbow at elevation 678.92 feet. The elbow reduces the diameter uniformly to 28 feet at the point where it connects with the spillway tunnel. The flood control outlet works, previously described, connects at this elbow. An air vent leads from near the top of the elbow to the top of one of the antivortex vanes. The spillway tunnel extends downstream 1,893 feet from Structural Design. The crest structure and approach structure are located in the Panoche formation. Bearing tests conducted on similar foundation material indicated a maximum allowable foundation diameter cut-and-cover conduit, 111 feet in length, ends at the transition to the stilling basin. The transition is 100 feet long and changes from a semicircular section to a rectangular section. Within this length, pressure of 3,000 pounds per square foot. The crest structure was analyzed as a gravity structure. The loads on the weir were calculated with the water surface at elevations 745 and 764.6 feet. Full uplift pressures along with horizontal and vertical seismic forces were considered. The concrete in the throat transition and shaft was analyzed as horizontal rings subject to uniform lateral rock loads and hydrostatic pressures. The antivortex piers are concrete structures cantilevered vertically from the spillway the invert elevation crest. the elbow to the downstream portal, and a 28-foot- falls 15 feet. Hydraulics. The Federal Government, acting through the U. S. Army Corps of Engineers, participated in the flood control aspects of the project and initially required that the maximum discharge during the standard project flood be not more than 7,000 cfs (the capacity of the downstream channel allowing only slight damage). This limitation was placed on an occurrence of the standard project flood with reservoir level at the spillway lip and the flood control outlet not being used. Routing of the standard project flood (spillway weir elevation 745 feet) resulted in a peak discharge of 7,500 cfs. To reduce the peak discharge to 7,000 cfs, it would have been necessary to raise the weir elevation and the dam crest. The Corps decided that the additional cost of construction to lower the discharge was not warranted and set the final criteria for the maximum discharge during the standard project flood at 7,500 cfs. Discharge during the maximum probable flood would be 44,200 cfs with a maximum water surface of about 765 feet, leaving 8 feet of freeboard above the resulting water surface. Flood hydrographs are shown on Figure 212. The spillway stilling basin (Figure 213) was designed so that the hydraulic jump would not move upstream into the conduit. To avoid negative pressures on the floor of the basin, the vertical curve was made flatter than the trajectory of a free-discharging jet. The stilling basin will contain a full hydraulic jump for all flows up to 7,500 cfs. Model studies indicate a partial jump is contained for flows up to 10,000 cfs. A flip sill was placed at the downstream end of the stilling basin to create a discharge trajectory with impact greater than 80 feet from the structure for flows ranging between 10,000 cfs and 44,200 cfs and to keep the dynamic load on the sill to a minimum. The excavated portion of the return channel was designed to carry flows up to 4,400 cfs without expanding to an overbank condition. This is the capacity the natural downstream channel can carry without causing flood damage. Water is released through the flood control outlet works when the reservoir surface reaches elevation 702 feet during the flood season. The concrete tunnel lining and stilling basin de- dynamic forces of floodflows as well as loading due to the reservoir and backfill. Where dynamic loading is critical, one-third overstress (one-quarter in end sill) is allowed and, where static loading is critical, normal stresses are allowed. Structural design of the stilling basin considered loading of the backfill as well as static and dynamic loading of water during flood discharge. One-quarter overstress was allowed in the end sill when dynamic loads were considered. A drainage system under the transition and stilling basin, consisting of interconnected longitudinal and transverse vitrified clay pipes, relieves uplift pressure, distributes pressures uniformly, and provides a drainage path for the water. signs considered static and Mechanical and Electrical Installations Power to operate the mechanical equipment at Del Valle Dam is supplied from Del Valle Pumping Plant to the outlet control house, located at the downstream toe. From there, power is extended to the other facilities at the Dam (Figure 214). The Pacific Gas and Electric Company supplies 480-volt, 3-phase, 60-cycle Del Valle Pumping Plant. Only the motors that drive the gate operators, sump pumps, and ventilators can make direct use of this power. For all other uses, the power is transformed to 120 volts, single power to phase. Flood Control Outlet Works. The high-pressure can be opened or closed in 15 minutes by a motor-driven hydraulic operator. The control panel is in the gate chamber. Air for ventilation is supplied through an 18-inch aluminum conduit. Air for the slide gates is furnished by two 24-inch aluminum ducts routed through the acslide gates in the flood control outlet cess tunnel and shaft from the intakes in the control house located over this shaft. An emergency generator, capable of producing the power to operate the flood control outlet works in case of installed in this control house. power failure, was 253 254 Figure 212. Flood Hydragraphs 164,006 INFLOW SOUTH BAY AQUEDUCT SPILLWAY DESIGN FLOOD STANDARD PROJECT FLOOD DEL VALLE DAM AND RESERVOIR 45..- 780- In F) FLOOD OUTFLOW ESHVHOSIG ELEV. 764?6 NQTE: BASED ON CORP OF ERS DATA ENGINE 760 FLOOD STA SE HEIGHT $1 STAGE HEIGHT OUTFLOW IE1 WEIR ELEV. 745.0 I 13 Nl NouvAa'Ia a?vaunsj 750 HELVM TIME IN HOURS twang-(1925' .5 I ,w-I um ?at: -762 nae/2!! ??mga a an: . a a we sumn\ Drum! 5 ?my; 1; .77 .1 nan-er? 2/ I I dro-?trc'plqt mam a um .ggluw and :1"an v?v?5?1! II I5 Dig.hovgg a.nr,\ A [no 0/ II I ?Mum Eih?hj Elev 525 I- nail?? In?1.5 .3. fypvea/ all bay: gnawNo?e Dela-I: ol cuter ?on! an ?31' \m-rud ham yuan'al gm,? no ?mm?m- W?hm 4f or Jlrurmrt- or SULLING .1 "Hm - 7 . o' VCD yen: and 57A 31?42_57_ 70 575 23". Scan; r, A ?51. 12 .aa .12 y? Elev 5630 I, no? I I 95O49 Figure 213. Cancrtie duvqn hand qn - .maa ?lv. I: -za.aaop:y 2 ?e-nfareemlnl Shall nan Ulla! covor a/ .- Imm un- en.? ?My. nalcd shall can/arm v. naled Ad ?Aall ?oap(d nor 4am! -. .ar "0'96 5 All bur: no: 'nd yuan; he ?Ind uezaraanc. w-Ih a; Mud Spillway S?lling Basin 1' .mr and cleanog! IraL?s- CI 2. :95rmumu I 1.. Lananudvnal ELEVATION - to 5? Urn-nag Na 0.9?fa'all rq n-I?nri '0/srulmy anwauv .chy.wmu 1? . x_,l re 3 - Ia: Squall, spazod I new u-T?q Headwa'l {or vT??'a?'if +3 Cu? I tcver canm unasw If; game; . . ?_1?Ii Na-e Inn.? mu, or hen! n1 shown .x A A -G 5; HVH DEL VALLE om A :Esznvom 4A5. ., A SPILLWAY . a 5 I Tunsmou AND s?rILLIna usm AND coucnn: neums mm". mm un- I .- [no-13m "674-854 .1: W4 "f ?Wm 1?33.? 255 256 4b. 120? - r419 .. .. .. ?qr-u 4? 3mmJar! water.37? mm Amp a ., Spare Spar! Spal'v Spare 5?11 'ran mus: cw'?m 770M OUTLET WORKS 2V, .3 wags?? . yarn}, J'Jva ?19587- n/(I me7/?5?O' 59: Dv?all 0.9 6-4774: 4 Figure 214. Single-Line Electrical Diagram Confro/ Nay." feed (?a?W?al ?brils PLAN Sta/0 I Nausw 9an? 5px! ~oaierJ?r? ??ka?r ~beer-q Spar! 5paro Span- Spa/'0 spare Usq' m, . ,4 l)mI! 4 VA, ?6 I ?Va/vo mndamr Sump . ?:arwmona 9mm MP :5 Pan-I FL J0 ?ak/(S Insf' . new! Tormmal mil am (4/156, . '3 man .- k, burn ?on fro! Haulour: u. aw . -mber 934' w~ . :o 0 'paro (par. 4 . 0531'?; ?i'cmvrotl mm 5 .54 {?uhef Wail: NOTES Wad ro-nrr'd far fun/'0 ul' 2 (I ghallbo luvs/led app-alumni, :nmvn 2' mug of read, I Around SAFETY .- Nun?.7 .- WATER tun-um ?mm-ta nnA-?mm a! nun- hm!- nmuo. u- . . . tut-um! Imunvmluv OIL VILLI DIVIJIGI rm. VALLE mu AND ussnvom ELECTRICAL SINGLE LINE DIAGRAM AND AREA PLAN . 1 . Shphoru mm. a "(9th ?57 A Ion-u Conservation Outlet Works. The 42-inch butter- fly-valve operators in the sloping intake are activated from a motor-driven pump in a control house located above the intake. The operator for the 60-inch butterfly valve is activated by a motor-driven pump located in the conservation outlet works valve chamber. Operating time for all butterfly valves is four minutes. Two 10-inch vacuum valves were installed on the downstream side of the 60-inch butterfly valve within the valve chamber. Air for ventilation is supplied by a blower in the conservation outlet works through an 8-inch aluminum conduit in the walk-in tunnel. The fixed-cone dispersion valve in the conservation outlet works can be opened or closed in five minutes by a motor-driven hydraulic operator in the outlet control structure. A sump and sump pump that drain the walk-in tunnel are located on the right side of the outlet control structure and empty into the spillway ,j I basin through a 2 '/2-inch, galvanized, steel pipe. The manually operated, blowoff valve for the conservation outlet works empties into the same chamber 6-inch, as the 42-inch fixed-cone dispersion valve. ! Construction ; Contract Administration ' General information about the contract for the conDam and reservoir. Specification No. 66-01, is shown in Table 25. This contract included the construction of the Dam and its appur- struction of Del Valle tenant structures. TABLE 25. — Major Contract Del Valle bid amount Final contract cost Low Total cost-change orders --. Starting date Completion date... Prime contractor 3242 3/28/66 9/17/68 Diversion and Care of Stream During the summer of First Construction Season. the first construction season, 1966, a trench was excavated across the valley at the upstream toe of the Dam. Collected water was pumped into a 12-inch pipe running along the county road and discharged into a below the Dam site. A cavated from the settling basin to the stream for return flow. The original streambed between the return point and the downstream toe of the Dam then was used as a spoil area for tunnel muck from both the flood control and conservation outlets. The foundation for the Dam was excavated, the curditch settling basin ; I ' I I ! was ex- grouted through a grout cap, and embankment placed to the original level of the streambed. A flood control channel was excavated from the downstream toe of the Dam to return floodflows to the original tain ; I channel. That winter, divert the stream through the conservation tunnel when the flow fell below 50 cfs so embankment place- ment could begin. This occurred on May 11, 1967. The only water flowing downstream through the conservation outlet works during the summer was leakage through the cofferdam which was diverted by a 12-inch pipeline through the tunnel to facilitate the remaining work on the outlet. the fall of 1967, the Dam had been topped out, but the flood control outlet works was not yet operable. The diversion plan for the winter utilized the reservoir as a temporary detention basin by releasing the flows through the conservation outlet works. This diversion operation would control a 100-year flood with the maximum reservoir stage at the invert elevation of the flood control outlet works, 40 feet above the crown of the conservation outlet works. A steel bulkhead was available to place in the stoplog slot of the flood control intake should a larger flood occur. The empty reservoir capacity would have contained the entire maximum probable flood volume well below the crest of the spillway. The winter of 1967hS8 was By exceptionally dry, and stream diversion during this period did not present any problems. _ Green Construction Co. & Winston Bros. Co. I I caused only minor damage. Second Construction Season. In the spring of 1967, a cofferdam was installed around the inlet end of the conservation tunnel, and 36-inch and 24-inch corrugated-metal pipes were installed through the cofferdam into the tunnel. The contractor's plan was to Third Construction Season. Following an extremely dry winter, the streamflow was low enough to allow placement of the permanent plug in the diversion portion of the conservation outlet works on May 16, 1968. The storage of water behind Del Valle Dam essentially began on that date. Reservoir 66-01 216,577,802 ?16,520,404 Specification . Dam and cfs a maximum streamflow of 5,600 Foundation Dewatering. During streambed excavation and curtain grouting, the diversion across the channel at the upstream toe of the Dam adequately dewatered the foundation. Before any embankment could be placed, it was necessary to cut off all flow into the excavated area. This was accomplished by installing a system of French drains just downstream of the cutoff trench. These drains joined a rock-filled sump 50 feet downstream of the upstream toe of the Dam. A 15-foot length of 24-inch corrugated-metal pipe was placed vertically at the low point of the sump, and the water collected was pumped into a 12-inch discharge line by a float-controlled pump. Excavation. The first area excavated was the foundation for Zones 1 A and 3 and upstream Zones IB and 2A. The excavated material was hauled to Zone 3 and 4 stockpiles. Inspection of the exposed foundation revealed that it was suitable for acceptance of Zone lA material without the additional 3-foot depth of excavation required by the plans and specifications. I 257 A The second area excavated was in the vicinity of the upstream and downstream portals of the conservation outlet works and most of the foundation area below elevation 668 feet between the two portals. A bench was constructed along the right abutment to facilitate construction of the conservation outlet works during the winter season. The excavated material was loaded at the base of the abutment and hauled to the Zone 4 tain holes to control surface leaks while grouting the stockpile. grouting pressures exceeding 1 psi per foot of hole depth. The pressures were limited to 0.50 to 0.75 psi per foot of hole depth. When excavation of the lower part of the right abutment was completed, isolated pockets in the Zone 1 area of the streambed were cleaned out and the material hauled to the Zone 4 stockpile downstream of the Dam. The third major area excavated was the streambed between the downstream limit of Zone lA and the downstream toe of the Dam. All material suitable for Zone 3 was placed directly in upstream Zone 3 and remaining material was hauled to the Zone 4 stockpile. The shear zones were excavated and filled, completing the preparation of the streambed portion of the foundation on October 10, 1967. The embankment for the Dam then was placed to the original level of the streambed in accordance with the plans and specifications, except that Zone 2A material was temporarily substituted for Zone 2B material. Otherwise, silt from the winter flows would have infiltrated Zone 2A material, destroying the drainage characteristics. After the flood season, surplus Zone 2A was trimmed back and replaced with Zone 2B material. In January 1967, work commenced on the fourth area to be excavated, the upper portion of the right abutment below the access road. Dozers side-cast material from the cut where it was loaded at the base of the abutment and hauled to the upstream spoil area. Boulders were separated and hauled to the upstream riprap stockpile by end-dump trucks. In February 1967, stripping commenced on the fifth and last area, the left abutment. The material was hauled to Zone 3 and 4 upstream stockpiles. In May, a surface crack appeared at Station 33+00 normal to the dam axis revealing a slide potential on the abutment. Four thousand cubic yards were placed and compacted between Stations 29+50 and 37 + 50 extending from the streambed (elevation 555 feet) to elevation 620 feet to stabilize the abutment and prevent a slide. Flood Cleanup. Cleanup of foundation debris resulting from the first season flooding was completed on May 27, 1967. Material suitable for Zone 3 was spread to dry in upstream areas, and material suitable for Zone 4 was hauled to a stockpile. Dam The starting grout mix (water-cement ratio) for both blanket and curtain grouting was originally 7:1, gradually increasing in thickness to A or Y^: as neces\ The I mix was later changed to 5:1. Grouting pressures were controlled carefully liecause the foundation could be deformed easily with sary. starting Blanket Grouting. Drilling and grouting of the blanket holes were done in one or two stages, depending upon the water-pressure test results. The holes were drilled to a depth of 15 feet, washed, and watertested at a maximum pressure of 10 psi. If the water loss exceeded 0.5 cubic feet per minute, this interval was grouted and then the interval from 15 to 25 feet was drilled and grouted. If the water loss was less than 0.5 cubic feet per minute, the hole was completed to a depth of 25 feet, then washed, water tested, and grouted. In areas of very disturbed rock, no water testing was done. Initially, the blanket holes were arranged in a triangular pattern over the entire Zone 1 foundation area. Later, the plan was modified to concentrate the blanket grouting near the grout curtain and the upstream portion of the Zone I foundation. Two additional rows of blanket holes were added: one 10 feet upstream from the curtain with holes on 10-foot centers and the other 20 feet downstream from the curtain with holes on 20-foot centers. Curtain Grouting. The curtain grout holes were arranged in two parallel lines, about 15 feet apart, running the full length of the Dam near the center of Zone embankment foundation. mary holes 100 feet deep on 40-foot the 1 Initially, pri- centers were drilled and grouted; then 75-foot-deep secondary holes between the primary holes were drilled and grouted. In areas of relatively high grout take, the spacing was split even farther, with additional holes 50 feet deep. Final spacing was l'^, 5, or 10 feet for the curtain holes. The curtain holes were drilled and grouted in stages of 25 feet (Figure 215). To test the effectiveness of the curtain grouting, 32 holes were drilled and grouted in a plane midway between the two grout curtains. These holes were drilled at angles of 40 to 60 degrees with respect to the curtain holes. Most of these holes were tight when water-tested or they had negligible grout takes. The grout take was far less than anticipated. Only 47,163 cubic feet of the estimated 150,280 cubic feet were used. Foundation Grouting Dam foundation grouting included blanket grouting to seal near-surface voids and curtain grouting to form a barrier against seepage beneath the Dam. The blanket holes were drilled and grouted before the cur- 258 curtain holes. Embankment Materials Impervious. Zone lA material was acquired from Borrow Area L located approximately 4,000 feet east of the Dam site on terrain that slopes into Arroyo Del Dam site to a point about 5 miles upstream. processing plant was established approximately 3 miles upstream from the Dam site, in the Arroyo Del Valle stream channel. The processed material, fairly well-graded from the '/-inch size to the No. 200 sieve size, was hauled from the plant to the embankment in 25-cubic-yard-capacity bottom-dump wagons. Material in Borrow Area S was, in general, a homogeneous sandy gravel composed of subrounded to rounded particles of resistant sandstone, cherts, schists, and assorted igneous and metamorphic rocks. The material particle size generally was less than 8 inches. from the The Figure 215. left Abutment Excavation and Curtain Grouting Valle (Figure 216). This material is composed of clays and sandy clays from the Livermore formation. Prior to excavation, the contractor prewet Borrow Area L to moisture-condition soils which would be used in the embankment. During initial excavation in the southwest corner, unsuitable sands and gravels were encountered. The contractor then moved to other areas and obtained acceptable materials although the borrow was heterogeneous at times. Scrapers were loaded downhill so that materials from the different strata would be mixed, resulting in a more homogeneous embankment. I I I Transition. Zone IB is the impervious transition between the Zone lA and Zone 2A filter. Zone IB is more coarsely graded than Zone lA and was obtained from alluvial soils in Borrow Area P, located about 3,000 feet upstream of the Dam site adjacent to the southern limit of Borrow Area L. This material was old alluvial soils from stream-terrace deposits. The borrow deposits occurred in two zones: an upper zone of impervious soils derived primarily from the Livermore formation and a lower zone of semipervious terrace deposits. The alluvium in Borrow Area P contained erratic lenses of gravel and clay. Satisfactory mixing and blending was achieved by prewetting the surface prior to excavation and crosscutting the alluvial fans. The bulk of Zone IB was taken from the northeast portion of the borrow area. 2 A in the downstream portion of the the filter between Zone IB and the pervious drain. Zone 2B. In the upstream portion of the Dam, Zone 2A acts as a drain during reservoir drawdown. Material for Zone 2A was processed from materials obtained in Borrow Area S, which extended Filter. Zone embankment is Drain. Zone 2B is the drain zone designed to convey seepage from the core and abutments to the downstream toe. Zone 2B is a coarse material with 100% passing the 4-inch sieve with no more than 5% permitted to pass the No. 4 sieve. This material was processed by the same plant previously described. Material was obtained from Borrow Area S. Due to the gradation of material in Borrow Area S, an excess of Zone 2B resulted while obtaining the necessary quantity of Zone 2A and cobbles. By change order, the contractor was permitted to place the 30,000 cubic yards of surplus Zone 2B material in the above elevation 755 feet at Zone 3 embankment no additional cost. Zone 3 forms a portion of the outer shells of the Dam. Zone 3 comprises the bulk of materials placed in the embankment, some 2,171,834 cubic yards. Material for Zone 3 was stream-channel gravels excavated from Borrow Area S. Some Zone 3 Outer Shell. material also was acquired from foundation excavation. Random. Zone 4 is a random zone forming porupstream and downstream shells. This zone accounted for the second largest quantity of tions of the material placed in the embankment. Materials for Zone 4 were acquired from stockpiled material from the dam foundation, open-cut excavations, spillway tunnel and shaft excavations, conservation tunnel ex- and from the specified borrow areas after were exhausted. Zone 4 materials are clayey sandstones, shales, and talus. cavations, stockpiles gravels, Slope Protection. Cobbles also were obtained during the processing of materials from Borrow Area S and were placed on the embankment slopes for erosion protection. By change order, the upstream cobble thickness was reduced to 1 foot. The reduced quantity conformed more nearly to the amount available after obtaining the necessary quantities of Zone 2A and Zone 2B material. The specifications required all material to be coarser than 3 inches. Riprap required for upstream slope protection, stilling basin outlet, and downstream channel was obtained approximately 26 miles from the Dam site. The source was existing stockpiles of large rock removed during excavation of the California Aqueduct. The rock was reduced to proper size by a pneumatic im- 259 .. - . g?g?fic n-nxn.lnu ml u. OON z_huu_n5m m0?. omiaoz uzi?o col! I I II I b?t/In (0&000?0? btet lull 3:5! ytiaut. 23 5:530. ?2.55 Innl Emma I - 33.. . f/X?/bldouflucn i?iitcli inc. 2.556 . ?an??d via 03 Shun? .?nuq?nunhu? . .. . 5 I > ^^ ! I < i? i ^ H »fei! iim \ Figure 270. ii t^ Control Schematics 32S Construction Contract Administration General information about the major contracts for the construction of Cedar Springs Dam and appurtenances is shown in Table 34. The principal contract, Specification No. 68-30, included the Dam, relocation of forest service roads, part of State Highway 173, access roads, inlet works, a portion of the Mojave Siphon, and the outlet works tunnel and control structure. Exploration Adit Portal excavation for the exploration adit, which became the access tunnel, began in September 1967. A trench was dug extending north from the later Highway 138 (Figure 248). TemHighway had to be relocated around the Figure 271. portal across State porarily, the north end of the trench while a conduit pipe for access proposed tunnel was being placed in the trench and the Highway rerouted over the top. Tunnel excato the vation began in October 1967 and was completed in March 1968. Two jacklegs were used to drill holes 4 to 7 feet deep. The drilling pattern was a 26-hole burn cut and a 14- to 26-hole "V" cut. Muck was loaded into muck carts with an air-powered Tunnel support from the mucker. portal to Station 26 + 03 (Figure 260) consisted of temporary timber sets placed on centers of 4 and 8 feet. Wood sets consisted of 10-inch by 10-inch caps and 6-inch by 8-inch posts. A 36-foot section between Stations 22+48 and 22 + 84 was driven 14 feet wide and left unsupported. It was used as a car pass area. From Station 26 + 03 to the end of the adit, W4X13 (4WF13) horseshoe steel sets were used for support. While driving the adit, support generally followed the face by less than 10 feet but, in places, as much as 70 feet of tunnel was left unsupport- ed for several days. During the first winter (1968-69), two delays amounting to 24 calendar days were a result of two storms. The first storm caused flood conditions so severe the entire vicinity was declared a disaster area by the Governor of California. All construction work, including excavation for the spillway and reservoir clearing, was halted by this storm. A second storm TABLE 34. Total cost-change orders Starting date Completion date Prime contractor 3, 1969. began on a small Las Flores diversion structure to bypass summer streamflow around the construction area. A 36-inch-diameter corrugated-metal pipe was laid through the Dam site. Since no rainfall occurred during the summer of 1969, the system remained dry. Because streamflow in the Mojave River was insufficient to meet construction needs, the Department developed a 2,250-gallon-per-minute well in the Mojave River, 9 miles downstream, and pumped water to the After April dam 1, 1969, construction at the site of the area of use. During the first phase of dam construction, the River was diverted through the Dam site west of the right abutment to allow completion of right abutment excavation and foundation grouting. By October 1969, right abutment excavation, core trench excavation, and foundation grouting had progressed sufficiently permit commencement of construction of the flood diversion channel located along the right abutment (Figure 271). The completed flood channel was triangular in shape and was formed by the excavated right abutment slope and a 5:1 filled slope on the left. The invert of the channel was at approximate elevation 3,165 feet. Major Contracts By April 1970, the first-stage embankment reached elevation 3,305 feet. Because the contractor demon- —Cedar Springs Dam and Appurtenances Interim Water Cedar Springs Exploration Adit Supply Facility Dam 67-36 67-50 ?39S,353 ?43 1,628 338,561 10/2/67 68-30 ?25,376.422 328,148,654 3429,060 Ji251,130 ?293,822 28,634 7/31/67 4/29/68 Clifford C. Co. 326 were resumed on March to Diversion and Care of River Specification Low bid amount Final contract cost Embankment Construction closed all routes to the job site and washed out haul roads to the spillway. Major excavation operations Bong & 4/9/68 R. L. Thibodo Construction Co. 11/12/68 8/18/71 Morrison-Knudsen Co. Stage II Pump 69-13 334,238 331,538 362 4/25/69 7/1/69 Pylon, Inc. Quarry Irrigation System 71-09 324,084 325,280 3925 5/21/71 8/13/71 Moulder Bros. strated that he could complete the outlet works, the spillway past Station 23+90, the spillway stilling ba- and the dam embankment to elevation 3,300 feet by November 1, 1970 (Figure 251), he was allowed to close the flood channel and proceed with construction sin, of stage two of the dam embankment. In an emergency, the outlet works are capable of passing the standard project flood with a maximum water surface at elevation 3,295 feet. After November 1970, floodflows were stored behind the Dam or di- I verted through the outlet works. 1 Dam Foundation Dewatering. Seepage of water into and along the bottom of the excavation for the Dam was controlled by using drain trenches and sumps. During stage 1 construction, the water was pumped from the sumps into either the diversion channel or the pipeline supplying Las Flores Ranch. Zone 1 and 2 embankment contact materials were placed over the dam founda- ! j tion in the dry. Excavation. left Stripping for the abutment knoll in December Dam 1968. ! i began on the The contractor feet. Below was moderately to slightly weathered, weak to moderately strong, and closely fractured. The stripping operation on the right abutment was accomplished by a large tractor with a ly I weathered and friable to a depth of 10 the severely weathered zone, the rock I , 1 I double-shank parallelogram ripper. Alluvium with an average thickness of about 30 feet and a maximum thickness of about 50 feet, including some slopewash at the base of both abutments, was excavated from the channel. The slopewash was 10 to 20 feet thick in both the left and right channel areas and generally consisted of silty sand. Minimal excavation was required in the Harold formation under Zones 3 and 4A, since it was as fresh on the surface as at depth. Further excavation was required in the granite under Zones 1 and 2 to remove all weathered rock to a depth sufficient to ensure that the foundation would be impervious after grouting. This resulted in the formation of a core trench, the excavation of which was accomplished using conventional excavating equipment without the need for any i I i i I I , ; \ j I 1 blasting. ] Ground water was encountered in the alluvium excavation from 50 feet upstream of centerline to 200 feet downstream of Station 21-1-75 (Figure 250). The water table was at elevation 3,167 feet. In addition, small seeps occurred as a result of cuts between elevations 3,180 and 3,185 feet in fractured rock associated j I ; : i i I with faults 1 and 5 (Figure 254). Prior to placing Zone contact material in the core trench, all loose rock, soil, and waste materials were removed using hand Cleanup and Preparation. 1 scribed for Zone 3. Little foundation because most of used a large tractor with a slope board. Two additional tractors were added to the left abutment stripping operation. The metamorphic rock exposed was severe- I labor and a backhoe. This was followed by a thorough cleaning using air and/or water jets immediately prior to placement of the contact material. No slush grouting was performed as it would have resulted in a rigid membrane inconsistent with the general design concept of a flexible embankment. Grout caps were placed in excavation where rock was too highly fractured or too soft to adequately anchor pipe nipples and hold the required grouting pressure. Foundation cleanup prior to placing Zone 2 material was the same as described for Zone 1. Embankment for Zone 3 was placed upon either Harold formation or granitic rock. After excavating overlying sands and gravel, loose material was either recompacted or removed prior to placing Zone 3. Boulders larger than 18 inches excavated from the dam foundation were utilized in Zones 4A and 5 of the embankment. No further cleanup was required. Foundation cleanup prior to placing Zone 4 material was the same as de- it cleanup was required for Zone 4A rests upon the upstream Zone 3 embankment. In those areas where Zone 4A was placed upon the dam foundation, all overlying topsoil, slopewash, and alluvial materials were removed prior to placement. Zone 5 Foundation preparation prior was the same as described for to placing Zone 4A. Handling of Borrow Materials Description. Materials for construction of the embankment were obtained from mandatory excavations and designated borrow areas. All materials from the mandatory excavations, meeting the requirements of the specifications, were used in the embankment in lieu of wasting. Impervious. Borrow Area A (Figure 245) was the source of impervious material for Zone 1 of the Dam. A total of 1,182,000 cubic yards of material was excavated to supply material for the core. The borrow source was an unnamed dry lake just north of State Highway 18 and approximately 20 miles from the Dam site. The contractor built his own 45-foot-wide haul road from the borrow area to the specified stockpile area in the reservoir. The dry lake materials were prewetted before removal from the borrow area for dust control purposes. Elevating belt loaders towed by tractors were used to excavate the clay to a depth of 3 to 5 feet in each pass. Maximum depth of excavation in the borrow area was 29 feet. At the Dam site, tandem bottomdump trucks deposited the material into windrows in the reservoir area. The windrows were spread into lifts for moisture conditioning, using tractors. A sprinkler system was used to apply water to the dry material. Discs and scarifiers mixed the material to assure complete and uniform distribution of the water. After moisture conditioning to optimum moisture content, the material was picked up and hauled to the Zone 1 embankment in scrapers. 327 Pervious and Slope Protection. Silty sands and gravelly sands for Zone 2 material were obtained in part from areas located in the reservoir. Of approximately 483,000 cubic yards of Zone 2 material, 108,300 cubic yards were excavated from the west side of the and the remainder from required excavathe spillway return channel and inlet works valley floor tion for excavation. The bulk of Zone 3 materials came from streambed sand and gravel on the dam foundation and in the upstream channel area. Excavation in the borrow areas was accomplished by cutting across deposits of sand, gravel, and cobble and through lenses and layers of differing gradation to produce a uniform mixture of materials within specified grading limits. Scrapers, push-loaded by dozers, were used to haul the material to the embankment. Boulders too large to be picked up by the scrapers were loaded by end loaders into rear-dump trucks for hauling to the rock embankment area of the Dam. Excavation from the four borrow areas was completed in March 1971. A total of 1,348,000 cubic yards of Zone 3 material was excavated. About 85% of the rockfill portion of the Zones 4, 4A, and 5 was excavated from ed in the reservoir area about 1 Dam for quarry locat- mile south of the Dam. The remainder was obtained from a stockpiles and man- datory excavations. Rock processed through the plant was rear-dumped into the plant hopper bins onto a hydraulically operated grizzly scalper which removed oversize rock for Zone 5 material. conveyor belt The remaining rock passed onto a which fed the separation plant. \'ibrat- ing screens in the separation plant divided the material into the required sizes for Zones 3, 4, and 4A. Rock for the various zones was collected in bins which fed dump trucks used to haul the material to the Dam. The oversize rock scalped off for Zone 5 material was loaded into end dumps by an end loader equipped with a tined bucket. The trucks hauled the rock directly to the Zone 5 embankment. Excavation in the rock quarry was completed in March 1971. A total of 4,629,000 cubic yards of material was excavated. Waste Areas. More than 7,500,000 cubic yards of material, stripped as overburden from borrow area and unsuitable embankment materials excavated from mandatory excavations, was wasted in five mandatory waste areas and two optional waste areas. sites An estimated 2,300,000 cubic yards of waste materi- was placed in a mandatory waste area located at the upstream toe of the Dam. Another waste area was al developed adjacent to the rock quarry to serve as a recreation beach. Materials placed in spoil areas did not require any compaction other than that derived by routing construction equipment over the fill. Dozers were used to By October 1969, overburden in the rock quarry area had been stripped to such an extent that large areas of hard rock were exposed. The basic equipment Embankment used to drill the rock consisted of air tracs, a drill, and compressors. In November, a rotary drill was brought to the job site and put on this work. Suitable rock was hauled in 75-ton rear-dump trucks, either directly to the dam embankment or to a rock-separation and processing plant. Waste material was hauled either to mandatory waste areas or used in haul roads. Shot rock was loaded by either a 15cubic-yard shovel or a loader. Impervious. The first Zone 1 contact material was placed in the core trench in October 1969. The contact material was compacted at optimum moisture content plus 2 to 3%. The moisture-conditioned material was hauled from Zone 1 stockpiles to the core trench in both scrapers and end-dump trucks. A front-end loader was used to place the material. Then it was compacted in nominal 4-inch lifts by a rubber-tired dozer. At least two passes were made on each lift: one parallel Figure 272. 328 Compacting Zone 1 Material level the material after Figure 273. it was dumped on the fill. Construction Performing Field Density Test on Zone 3 Moteriol Figure 275. dam axis and the other perpendicular to it. This method of placement, with minor modifications, was to the used to place all of the Zone 1 contact materials. Placement of contact material to a depth of 12 eminches was followed by the placement of Zone 1 bankment manner using sheepsmaterial was spread and in the conventional foot rollers (Figure 272). The dozer and compacted by selffour-drum, sheepsfoot rollers. Twelve passes with the sheepsfoot roller were required to compact the material to a maximum depth of 6 inches and to a required compaction of 95%. The top layer of foundation contact material, compacted by a wheelroller, was scarified to a depth of 2 inches prior to placing Zone 1 embankment. A total of 1,090,000 cubic material was placed in the dam emyards of Zone by leveled a rubber-tired propelled, 1 bankment. on each side of the core consist of Zone 2 materials of the Harold formation. Placement of Zone 2 contact material commenced in the core trench near the center of the east portion of the Dam. The material was hauled from stockpiles in the spillway return channel to the core trench where it was dumped. Then it was leveled with dozers and compacted in 3- to 4-inch lifts by a rubber-tired dozer in the same manner as described for the Zone 1 contact material. This method of placement, except Pervious. Filter blankets lying impervious Zone for special 2 1 problem areas, was used to place all Zone contact material. Zone 2 embankment placed over Zone 2 contact material was hauled in rear-dump trucks, leveled by dozers, and compacted by self-propelled, four-drum, sheepsfoot rollers to a required minimum compaction of 95%. The material was compacted in 12 passes to a maximum thickness of 6 inches. A total of 483,000 cubic yards of material was placed in the Zone 2 em- bankment. The gradation of Zone No. 200 screen to 3 material varies in size from 18 inches. The upstream Zone 3 Zone 5 Embankment material was extended in foundation and under the a Shell Material thick blanket along the Zone 4A embankment all the way to the upstream toe of the Dam. The materials were leveled by dozers and moisture-conditioned on the fill by water tankers. The material was compacted by two passes of a vibratory roller. Lifts were limited to a depth of 24 inches. Compaction tests were performed for every 10,000 cubic yards of material placed (Figure 273). required was 95%. A yards of Zone 3 embankment The minimum compaction total of 1,949,000 cubic material was placed. Materials for Zone 4 embankment, lying downstream of Zone 3, varied in size from 3 to 30 inches. The rock for Zone 4 was hauled in rear-dump trucks and spread on the fill by dozers. No moisture conditioning was required. Lifts were limited to 36 inches after compacting (Figure 274) with two passes of a vibratory roller. A total of 776,000 cubic yards of Zone 4 material was placed in the dam embankment. Placements for Zone 4A embankment commenced on June 24, 1969. A total of 2,460,000 cubic yards of Zone 4A material, varying from sandy gravel to 30inch rock, was placed in the embankment. Little foundation cleanup was required for Zone 4A since most of this material rests upon the upstream Zone 3 embankment. In those areas where Zone 4A was placed upon the dam foundation, all overlying slopewash, and alluvial material were topsoil, removed prior to placement. Rock was leveled on the fill by dozers, moistureconditioned by water tankers, and placed in 36-inch lifts. Compaction was accomplished with two passes of a vibratory roller. Slope Protection. No moisture conditioning or compaction was required on Zone 5 embankment rock. Dressing of the 2'/4:l downstream slope of the Dam was done by dozers. A total of 784,000 cubic yards of Zone 5 material was placed in the dam em- bankment (Figure 275). 329 Riprap. Riprap for the upstream face of the Dam from elevation 3,305 feet to the dam crest varied in size from 3 inches in diameter to 2 cubic yards in volume. Lifts were limited to a depth of 5 feet. was somewhat slower than those placements made on the 2% slope and caused more segrega- of the chute tion problems. For concrete placemenis on the lower reach of the slope section, a 60-ton truck crane and 1-cubicyard buckets were used to handle the concrete. A conveyor belt system was used as the placement progressed uphill and out of reach of the crane. Floor concrete placements for the stilling basin were made using either a crane and bucket method or a conveyor belt system. The conveyor belt system was supplied by transit mix trucks. This method also was used to place the floor concrete for the approach channel and the ogee crest section. All forming was done with wood. All floor placements were completed by the time the contractor placed the cover slab over the 50% Spillway Open-Cut Excavation. Spillway excavation was December 1968 in the upper reach of the spillway and in the return channel. The material exstarted in cavated from the upper reach of the spillway that was unsuitable for embankment was wasted at the dam toe, while the material excavated from the return channel was either wasted in the downstream waste area or used to build the construction facility earth pad. The initial construction equipment used to strip the vegetation and overburden consisted of dozers equipped with rippers and slope boards, push dozers, and scrapers. outlet works tunnel portal. The first concrete placement After stripping the vegetation and overburden, the initial excavation was in weathered granite. As the excavation progressed deeper, the material ranged from decomposed granite to hard rock. The rock was moderately to highly fractured. Air drills were used where rock was too hard to be ripped. In some isolated areas, rock had to be blasted. In addition, some boulders were encountered that had to be shot and pushed over the side of the cut into the reservoir area where they were later reshot for use in the dam embankment. All materials suitable for dam embankment were placed in the various rockfills of the Dam. By the end of July 1969, the excavation of the upper approach channel, crest section, and chute to the intersection of the outlet works had been completed except for final foundation cleanup and structural excavation. Open-cut excavation for the spillway from the intersection of the outlet works to the end of the stilling basin essentially was completed by December 1969, except for fine grading and structural excavation. A total of 2,2.'i4,750 cubic yards of material was excavated for the spillway. Structural Excavation. Structural excavation for the spillway included the shear keys and drain ditches below the bottom surface of the spillway floor slab. for the walls was made on the right side of the spillway at the vertical curve transition between the 2 and 22% slopes of the chute. The wall form consisted of steel panels faced with plywood. Prior to placing the concrete, considerable effort was spent anchoring the form to prevent grout leaks. A conveyor with rubber wheels on the botat the top was used to elevate the concrete to the top of the form where it was discharged through hoppers and tremie pipes. The concrete was vibrated by working off a platform at the top of the form. This method of placement, with minor modifications, was used to place all wall concrete except in the stilling basin walls, warped approach walls, and ogee crest walls. Concrete in the stilling basin walls was placed using concrete buckets handled by a 60-ton truck crane. The 45-foot-high walls were placed in three lifts, which varied from 11 feet to about 19 feet in height. Concrete for the warped approach walls and for the ogee crest walls was placed using conventional wood forms. The warped walls were placed in six lifts using holding forms while the crest walls were placed in three lifts. These placements were made using concrete buckets and a truck crane. 30-foot tom and track-guided wheels Some of the hard granitic rock in the spillway chute grade which resulted in considerable overexcavation. Drain trenches were excavated using a backhoe with a blade and by laborers using jackhammers. Rock too hard to be excavated with the backhoe was drilled and shot prior to excavation. Final cleanup of the was difficult to blast to Mojave Siphon Excavation. Inlet Works Excavation for the inlet works was all concrete was placed using a cut was a maximum of 150 feet deep in the granitics and varied from 25 to 60 feet in Harold formation on the lake side of the ridge. Cut slopes of 1 with 1 5-foot-wide berms every 40 feet in elevation, 1 were used in the granitics. Cut slopes of l'/2:l with a similar berm arrangement were used in the Harold formation where they were subject to submergence by the reservoir. Excavation commenced in the vicinity of Station conveyor system which discharged the concrete into the form ahead of a screed. The concrete was screeded by a steel slip form pulled up the slope by winches. Floor concrete placement on the 22% slope section 15-1-00. The excavation work for the first nine months was, for the most part, confined to the reach between Stations 12-1-00 and 18-1-00 and was on an intermittent basis, depending upon the availability of scraper units open : foundation prior to placing concrete was done with air-water jets. Concrete Placement. The first floor concrete placement for the spillway was on the 2% slope section of the chute. 330 The cut. The , from other phases of the work. The work during this period basically was a dozer and scraper operation. When excavation had progressed to elevation 3,380 feet, a small slide on the fault plane was observed in the approximate area of Station 17 + 00, centerline right, at about elevation 3,450 feet. The contractor was directed to perform additional excavation from Station 14 + 00 to Station 19 + 00 to correct this problem. Approximately 77,000 cubic yards of material was removed above the fault plane. Major equipment used to remove the slide consisted of dozers with rippers, scrapers, track drills, end-dump trucks, and an end Excavation was completed in September 1970. Pracexcavated material was wasted at the upstream toe of the Dam. Exclusive of the slide, a total of 727,100 cubic yards of material was excavated for tically all of the the inlet works structure. Structural excavation for the concrete inlet works key and drain trenches under the chute floor slabs was performed using a backhoe or jackhammers, depending on the nature of the rock. Considerable care was exercised to prevent shattering the rock beyond the excavation neat lines. Concrete Placement. Floor placements for the upper reach of the chute and the transition structure were made by chuting concrete directly into the plywood-faced forms. The walls were placed using concrete buckets handled by a 60-ton truck crane. Floor and wall placements for the 41% slope of the chute and for the dissipator structure also were made using the crane and bucket method. The contractor used a job-built slip form screed to place concrete in the invert of the 41% slope of the chute. Two cables powered by an electric winch were used to pull the slip form up the slope at a slow rate of speed while vibrating the concrete just ahead of the screed. A total of 2,634 cubic yards of concrete was placed for the inlet works structure. Concrete Holes for the 24-inch-diameter, under the inlet works dissipator structure were drilled using a crane-mounted auger drill rig. No particular problems were encountered in placing a total of 374 feet of Piles. 30-foot-long, cast-in-place, concrete piles piling. Mojave Siphon Extension. for the Debris Barriers Two debris barriers were constructed under this One barrier is located in Miller Canyon in the southeast fork of the reservoir and the other in Cleghorn Canyon in the southwest fork of the resercontract. loader. 'OK excavation, proceeded uphill (southerly) toward the inlet works structure, except for the first 250 feet south of the existing Mojave Siphon which was installed last. The pipe installation sequence consisted of laying the pipe to grade, testing the rubber gasket ring for sealing, grouting the outside portion of the joint, installing bond cable at each joint, grouting the inside portion of the joint, and backfilling the pipe. A total of 1,177 linear feet of pipe was installed. Open-cut excavation Mojave Siphon pipeline extension commenced north of relocated State Highway 173. Excavation progressed uphill (southerly) toward the inlet works structure, and then the remaining reach of the excavation under State Highway 173 was performed. Dozers and scrapers were used to excavate a total of 33,400 cubic yards of material for the pipeline. just Pipe Installation. The first section of the 126inch-diameter Mojave Siphon pipeline extension was placed in the open-cut trench 250 feet south of the existing Mojave Siphon. Pipelaying, like the open-cut voir. These barriers were constructed across the streambeds of the two canyons to catch debris coming down the canyons after closure of the diversion channel through Cedar Springs Dam. Consequently, construction of these barrier dams was prohibited prior to closure of the diversion channel. Immediately following construction of the debris barriers and prior to reservoir filling, a large-magnitude flood overtopped the Miller Canyon dam and washed out a section containing the spillway. Just before reservoir filling, this section was replaced along with a 48-inch corrugated pipe to bypass flow during reconstruction. Drainage Gallery The 8 drainage gallery. Station + 00 to Station + 22, was driven initially for exploration purposes, as part of the exploration program discussed previously. Except for mucking out the caved-in materials of the exploration adit, no excavation was required in the drainage gallery. One extensive cave-in had to be mucked out at the beginning of the tunnel in the vicinity of Station 1 + 50 (Figure 260). The remaining work in the tunnel, prior to placing concrete, consisted of laying track, bringing in utility lines, providing for drainage, realigning existing steel sets, reinstalling fallen lagging, and installing additional lagging where required. The tunnel section between Stations 8 + 22 and 8 + 64 (Figure 260) was driven northward from the dam foundation under the main dam contract. The first concrete placedrainage gallery tunnel was between Station 8 + 00 (approximately 22 feet from the drainage gallery extension) and Station 6+70. Subsequent invert placements in the drainage gallery proceeded toward its intersection with the access tunnel. From Station 8 + 00 to Station 4 + 60, the concrete placements were made using a concrete pump located outside at the drainage gallery extension portal. A 6-inch slickline was used to convey the concrete directly into the invert forms. Usually, additional cement over the structure's design requirements was Concrete Placement. ment in the invert of the 331 added to the concrete to reduce friction in the slick- line. (bolts were % of an inch by 6 feet long), depending upon the nature of the granitic rock. The tunnel was in 4- to 7-foot rounds. The remaining reach of the drainage gallery tunnel invert from Station 4 60, and its intersection with the access tunnel, w as placed with the concrete pump located inside the tunnel. The concrete was pumped from the pump hopper directly into the invert forms using a 6-inch slickline. Length of placements varied advanced from about 60 the batch plant. + to 110 feet. The first arch placement in made at its intersection with the drainage gallery was the drainage gallery ex- tension, and subsequent placements proceeded toward its intersection with the access tunnel. A total of 14 arch placements, varying in length from 48 to 68 were made using a concrete pump and slickline from inside the tunnel. Collapsible steel forms were feet, used for these placements. The drainage galcrawler-mounted drill. Steel supports, heavily cribbed, were required only at the portal, as sound rock was encountered as the excavation progressed. Most of the blasted rock was mucked out through the portal using an end loader except muck from the last round, which was removed through the drainage gallery using a mucker and train. Concrete for the 6-foot-diameter drainage gallery extension was monolithically placed using a concrete pump and a slickline. The concrete was transported from the batch plant in transit mix trucks which dis- Drainage Gallery Extension. was driven using lery extension a charged their loads directly into the pump hopper. The upstream 8-foot-long plug was placed in a similar manner. The first concrete invert Concrete Placement. placement for the access tunnel was between Stations 28 + 97 and 29 + 62 near the outlet works gate chamber, and subsequent invert placements proceeded toward the portal. The concrete was transported by rail from A concrete pump with a 6-inch slick- was used to place the concrete. Placements varied from about 55 to 135 feet in length. line Concrete arch placements for the access tunnel after the drainage gallery arch was completed. Placements started at the gate chamber. Station 29 + 78, and progressed to the portal at Station 19 + 90. A total of 16 arch placements, averaging 68 feet each, were required. The method used to place the commenced concrete was the same as described for the drainage gallery arch placements. Outlet Works Tunnel The initial excavation of the gate continuation of the access tunnel excavation. A tunnel with a width of 10 feet and a height of 1 1 feet - 6 inches was driven to the centerline of the gate chamber and then to the air tunnel portal, thus completing the first phase of the outlet works excavaExcavation. chamber was a tion. After completing the excavation of the air tunnel, the contractor resumed excavation in the gate chamber by driving an 8-foot-diameter shaft from the floor of the gate chamber (elevation 3,196.30 feet) to the top of the dome. The dome at the top of the shaft was rock-bolted with 10-foot-long rock bolts on 3-foot cen- Access Tunnel Completion. Work began with mucking out sand and drainage water from the exploration adit tunnel and extending the track into the existing timber-sup- Mucking out the invert; laying track; water, and electric lines were continued until the intersection of the access tunnel and drainage gallery was reached. At the intersection, the crown of the tunnel had caved in from Station 2 + 65 to Station 25-f 88 in the access tunnel and to Station + 90 in the drainage gallery tunnel. The cave-in brought down all the previously installed supports. The cave-in was mucked out and the crown was resupported with several 4-inch and 6-inch-wide steel sets ported tunnel. and installing air, .S and timber lagging. While one mining crew continued work in the previously driven part of the access tunnel and in the drainage gallery tunnel, another crew started driving the access tunnel from Station 2.*! + 88 toward the outlet works gate chamber. Fairly good rock usually was encountered in the access tunnel as it was driven toward the gate chamber. In the vicinity of Station 27 + 87, three steel sets, W4Xl.^, on ."i-foot centers were used in a faulted area. In the remaining reaches, the tunnel was either driven bald-headed or rock-bolted Flgure 276. Rock Bolls in Dome of Outlet Works Gate Chombe 332 J A rod then was hung at the centerline of the gate chamber from the top of the dome to the springline of the dome from which a platform was attached. This enabled the miners to drill 17 feet 8 inches in any direction above the springline from the lower end of the downstream (north) portal where the tunnel discharges onto the 50% slope of the spillway floor. As soon as the fractured rock over the north portal was stabilized with the installation of crown bars into the overburden, a 3-set steel umbrella was installed at the the rod. The entire top 120-degree peripheral portion of the dome above the springline at elevation 3,212.30 feet then was drilled out and shot in one blast. The 30-degree slope bench formed by the blast served as a funnel, in effect, since the muck rolled down into the 8-foot-diameter shaft to elevation 3,213.50 feet where it was removed. The rest of the dome then was rockbolted on approximately 3-foot centers with rock bolts varying from 6 to 10 feet in length. The center shaft was enlarged to a diameter of 15 feet, and the remaining rock above the springline was drilled, shot, and rock-bolted (Figure 276). The chamber below the springline was excavated in three separate rounds working outward from the center of the 15-foot shaft on a 17-foot -8- inch radius. The walls of the gate chamber between the springline and the floor (eleva- portal and drilling commenced. The first shot opened cracks in the rock above the portal, and additional cribbing had to be installed along the sides and above the portal. The fractured rock at the portal extended into the tunnel for about 75 feet to Station 27-1-21 and ters. - tion 3,196 feet) also were rock-bolted. The contractor, throughout the tunneling, used the proper amount of tunnel supports without arguing that more support was needed for various reasons. This was due in large part to the lump-sum bid item for tunnel work which, in effect, made the contractor responsible amount of tunnel support used. for the The major equipment used to excavate the gate chamber included jackleg drills, stoppers, a mucker on rails, a mucker on tracks, five to seven 4-cubic-yard muck cars on rails, and an 8-ton motor-driven locomo- was supported by W6X15 centers, 27 + 21 steel sets with considerable lagging. on 4- to 5-foot From to Station 26-1-79, the granitic rock Station was fairly good, and no supports were required. The rock from Station 27-1-21 to Station 23-f 50, a point of contact with a shear zone, varied from slightly fractured to sound rock. As a result, this reach of the tunnel was either supported by W6X15 steel sets on 5to 6-foot centers or rock-bolted with rock bolts varying from 6 to 10 feet long, depending upon the nature of the rock. In the faulted area reaching from Station 23 + 50 to approximate Station 22+96, fault 1 was highly fractured and contained clay gouges. This area was supported by W6X15 steel sets on 3- to 4-foot centers and required extensive lagging. Between Stations 22+96 and 18 + 65, where the excavation broke into the previously excavated gate chamber dome, the quality of the rock varied considerably. In November 1969, driving of the 13-foot-diameter circular section of tunnel was commenced, leaving 3 feet of material in the invert to be excavated later. Station 17 + 81 to Station 13 + 68, the lightly fractured granite required rock bolts only in isolated areas to pin loose rock. Between Station 13+68 and the upstream portal, several 6-inch steel sets were required to support the rock. Major equipment used to excavate the outlet works From tive. The outlet works tunnel was driven upstream from included a drill jumbo, two end loaders, and five air compressors. The open-cut excavation for the outlet works intake structure was performed in conjunction with the open-cut excavation required for the spillway approach channel. Nine steel sets, with considerable lagging, were used to support the portal. Concrete Placement. The first two placements chamber were made to level the foundation to allow setting of jack plates and anchor bolts for the steel-plate liner supports. The concrete was transported from the batch plant to the gate chamber in transit mix trucks (Figure 277). For three months, the work in the gate chamber was limited to placing, fitting, and welding the steel-plate for the gate liner sections. Fit-up of the liner sections took longer than expected due to plate distortion and warping. Embedment Figure 277. Placing Concrete in Gate Chamber done in two of the upstream steel-plate liner was and the downstream liner in three lifts 333 lifts. All placements were made with a concrete pump and slickline. Three concrete placements were required in the sidewalls between the upstream and downstream liner to elevation 3,194 feet. Placements were made using conveyor belts to span the gate chamber. Conventional wood forms were used for these placements. The floor, remaining walls, and dome placements were made in five segments using a pump and slickline and conventional wood forms. Concrete was transported by rail through the access tunnel. Invert placements for the 13-foot-diameter portion of the outlet works tunnel upstream of the steel-plate liner in the gate chamber were made in seven sections. The first five placements were made using a 60-foot conveyor belt which discharged the concrete directly into the form. The last two placements were made using a concrete pump and an 8-inch slickline. The concrete pump and slickline method of placement proved to be the most effective, reducing the placing time by approximately 50%. Ten arch placements, starting from the gate chamber and varying in length from 48 to 56 feet, were required to reach the upstream portal at Station 12-f71. All placements were made using a concrete pump and an 8-inch slickline. The first invert placement for the downstream horseshoe section of the outlet works was made for the downstream transition from Station 18 + 84 to Station 19+17. This placement and the next six placements from Station 18 + 84 to Station 24+36 were made using a concrete pump with an 8-inch slickline. The remaining placements, except for the last one at the downstream portal, were made using a conveyor belt. The last invert placement was made using a concrete pump, set at the portal, and an 8-inch slickline. Prior to placing concrete in the arch of the downstream horseshoe section, 1-foot-high stub (curb) walls were placed on each side of the centerline. Transit mix trucks discharging directly into the steel forms were used for these placements, which were made well ahead of the arch placements. The arch placements were made using a concrete pump with an off a platform pinned to the shaft. Work was suspended at that time until a cable and air hole could be drilled shaft. from the ground surface Excavation of the to the air shaft heading in the resumed with drill- ing from the ground surface of an 8-inch-diameter hole in the center of the shaft. This hole was to serve as a cableway for raising a man-cage used as a work platform by the miners in excavating the shaft at higher elevations (Figure 261). Work continued using the platform until the shaft had been raised 87 feet from the invert. Then the miners began using the man-cage to excavate the shaft. The cage was hoisted from the ground surface using a 30-ton truck crane. The mancage was used to excavate all but the top 25 feet of the raise. This reach was excavated from the top of the shaft. Concrete Placement. The first placement consisted of 15 feet of invert and stub wall in the air tunnel to the centerline of the air shaft. The concrete was delivered to the top of the air shaft and lowered 180 feet down the air shaft in a 1-cubic-yard bucket where it was dumped and vibrated into the forms. The first air-shaft placement was made from the invert to elevation 3,230 feet and included 8 feet of the tunnel walls and arch. Six subsequent placements were made to elevation 3,376.5 feet or to 2 feet below the finished floor of the air-shaft louver house. Two shaft placements were made monolithically using two 6-inch slicklines extending from the top of the shaft to within 3 feet of the bottom of the placement. This method of placement for the air shaft produced good workability without segregation. The first air-tunnel invert and stub walls placement incorporated the invert of the air shaft. The remaining 78 feet of the invert and stub walls were placed using a truck-mounted pump located downstream of the works tunnel. Two conwere required to complete the airtunnel arch. Placements were made using a pump located at the upstream end of the tunnel, adjacent to the outlet works gate chamber. A 6-inch slickline was gate chamber in the outlet crete placements used to place the concrete in collapsible steel forms. 8-inch slickline. Concrete Production The outlet works intake structure was built using wood forms faced with plywood. The concrete was Three principal concrete mixes were used in the construction of the spillway, inlet works, and tunnels. placed using a truck crane and 2-cubic-yard concrete buckets. A mix Air Shaft Tunnel Excavation. Excavation for the air tunnel was a continuation of the outlet works gate chamber. The tunnel was driven through sound granitic rock and no supports were required. The method, equipment, and labor used to drive the tunnel essentially were the same as for the access tunnel excavation. Excavation of the air shaft was started on July 2, 1969. By July 7, 334 had been driven 46 feet tunnel by miners working 1969, the shaft from the invert of the air with 3-inch maximum size aggregate, 306 pounds of cement, and 70 pounds of pozzolan was used for the spillway and inlet works floor slabs and large walls, and for the entire intake structure. Thin walls of the spillway and inlet works have concrete with a mix of 1 '/2-inch maximum size aggregate, 400 pounds of cement, and 70 pounds of pozzolan. All concrete placed in the underground works consisted of a mix of I'^-inch maximum size aggregate, 447 pounds of cement, and 100 pounds of pozzolan. Using waterwashed and shaded aggregate, together with 100% ice, concrete was held below 53 degrees Fahrenheit during summer placement. This placement tern- perature was only 3 degrees above optimum for this type of work. A fully automatic 4-cubic-yard plant was used to batch the concrete for Cedar Springs Dam structures. The plant included a 4-cubic-yard tilting-drum mixer and individual batches of 6,000-pound capacity for the four sizes of aggregate. Cement and pozzolan were batched cumulatively in a 6,000-pound batcher. Ice was batched into a 2,000-pound batcher with adjustable feed discharge directly onto a belt. Water was metered through a 3-inch meter. Based on a 2 '/^-minute mi.xing cycle, the capacity of the plant was 80 cubic yards of concrete per hour. Grouting Dam Foundation. The curtain grouting program foundation involved a high-pressure, 150foot-deep, main curtain and a low-pressure, 25-footdeep, secondary curtain. One-and-one-half-inch-diamfor the dam were installed in all grout holes. Grouting was done by the split-spacing method. Primary holes were 150 feet deep on 20-foot centers with 50-foot-deep intermediate holes between the primary holes. The main curtain crosses the entire length of the Dam in a mid-position under Zone 1 and was combined with a line of holes in the secondary cureter pipe nipples , I I tain. Grouting of the main curtain was accomplished by combination of stage and packer grouting in the following sequence: first stage was drilled to a depth of 25 feet and stage-grouted from the nipple; second stage was drilled the next 25 feet, a packer was set at the top of this stage, and grouted; primary holes were completed by drilling the third stage the remaining depth of hole (150 feet); packer grouting from 100 to 150 feet; and subsequently setting a packer at a depth of 50 feet and packer grouting from 50 to 100 feet. Blanket grouting was done in fractured areas and [where grouting of the first stage in the main and seclondary curtains did not appear to be adequate to seal the upper 25 feet. Blanket grouting consisted of single lines of shallow holes (up to 25 feet deep) on 10-foot spacings, upstream and downstream of the curtain. a ^ ' : i Pressures of 10 to 15 pounds per square inch (psi) were used, although up to 25 psi was used occasional- I ly. Spillway. Curtain grouting for the spillway foundation was done by a procedure similar to that for the 'dam foundation except a secondary curtain was not included; maximum depth of drill holes was 125 feet in the bottom and 50 feet on the side slopes; and for [the third stage, the packer was set at 90 feet, and the Imaximum pressure was 125 psi instead of 150 psi. ! I Contact grouting was performed in the any voids between the concrete tunnel lining and the surrounding rock. Contact grout was injected through 1 '/j-inch-diameter pipe set in the tuninel lining near the crown. Grouting of a hole was considered to be complete when 30 psi could be main- Tunnel. j : i tunnels to fill tained for 15 minutes with no significant grout take. Consolidation grouting consisted of low-pressure shallow-hole grouting of the fractured rock surrounding the tunnel. This was accomplished by drilling and grouting a series of holes in a ring pattern equally spaced around the tunnel perimeter and perpendicular to the tunnel centerline. Grout pipe, l'/4 inches in diameter, was installed prior to placement of the concrete lining. Grouting of each ring usually was started at the tunnel invert, and every other hole was grouted progressing upward to the crown. Grouting was accomplished by setting a packer inside the pipe and grouting with a pressure of 50 psi. The intermediate holes on each ring then were drilled and grouted to fill any voids between the primary holes. Gate Chamber. Contact grouting was conducted chamber dome by using seven consolidation grout pipes which were located evenly throughout the dome. in the gate Consolidation grouting consisted of 61 holes included in six rings of 10 each, plus one hole at the top of the crown. Holes were drilled 20 feet into rock and grouting was accomplished in one stage. The rock surrounding the dome was hard to drill with diamond bits, and low grout takes were recorded. After reservoir filling, moisture was noted on about 50% of the gate chamber walls and ceiling. To maintain a dry condition for the electrical equipment, the Department contracted for additional contact grouting using a chemical grout. Seeping plugged grout holes, construction joints, and fine-line cracks were drilled, caulked, and pressure-grouted with acrylomide grout. The treatment proved to be about 95% effective. Additional grouting is planned in the gate chamber air shaft where moisture continues to be a problem. Air Shaft. Consolidation grouting was conducted in the air shaft for a vertical distance of 203 feet above the air intake tunnel. The grouting consisted of rings of four holes each on 15-foot centers. Grout take was low in most areas and 22 holes were tight. The only area with appreciable grout take was the south side of the shaft between elevation 3,201 feet and elevation 3,225 feet. Additional chemical grouting also is planned for the air shaft where moisture from seeping construction joints now drips from the walls. Reservoir Clearing Clearing in the reservoir to elevation 3,354 feet conremoval and disposal of all trees, down timber, brush, rubbish, fences, floatable material, and buildings. Cesspools and septic tanks were pumped out and filled with sand. Any trees between elevation 3,354 feet and the spillway weir crest at elevation 3,355 feet were left standing at the request of the U.S. Forest sisted of the It was believed that many of these trees would because of infrequent inundation, and those that die can be used by campers for firewood. Service. live I 335 Reservoir clearing and was completed bulldozers was used commenced in A December 1968 spread of four to clear the reservoir area, except for inaccessible areas which had to be cleared by laborers using hand and power tools. Combustible material, 336 in June 1971. except for commercial timber, was disposed of by burying or burning. All burning was performed in accordance with the project fire plan approved by the U.S. Forest Service. Merchantable pine timber in the Miller Canyon area was logged by a subcontractor. BIBLIOGRAPHY Lanning, C. C, "Cedar Springs Dam", USCOLD Issue No. 32, U. S. Committee on Large Dams Newsletter, May 1970. Sherrard, No. J. 3, and Allen, C. R., "Potentially Active Faults in Dam Foundations", Institution of Civil Engineers Geotechnique, September 1974. L., Cluff, L. S., The Stroppini, E. W., Babbitt, D. H., and Struckmeyer, H. E., "Foundation Treatment for Rock", ASCE Journal of Soil Mechanics and Foundation Division, October 1972. Volume XXIV, Embankment Dams on 337 SANTA ANA VALLEY T7 PIPELINE ,ATCH1S0N-T0PEKA R.R. a SANTA FE <66> III ' I I I M M I I f)SAN BERNARDINO I I ^jo'te ' > > •+-^-+^ +-* I I -p o UNION PACIFIC R.R. LV^ :^ 60 RIVERSID^M K SUNNYMEAD ATCHISONTOPEKA a SANTA FE- ^ Cu PERRIS DAM 'Z./5/CE PERRIS LAKE MATHEWS COLORADO ^RIVER mPERRIS '395' MILES 3 Figure 278. 338 Location Map — Perris Dam and Lake Perris CHAPTER XIII. FERRIS extension of the Santa the "inlet works". General Description and Location Perris Dam maximum is a zoned height of 128 with earthfill structure feet. The Dam is over 2 way. Water is Ana Valley Pipeline, termed Dam and Lake Perris, the terminal storage on the California Aqueduct, are located in northwestern Riverside County, approximately 13 miles southeast of the City of Riverside and about 65 facility and impounds a reservoir with a gross storage capacity of 131,452 acre-feet within a horseshoe ring of rocky hills. Approximately 20 million cubic yards of fill material comprise the embankment. Structures appurtenant to the Dam include a tunneled outlet works connecting to distribution facilities of The Metropolitan Water District of Southern Cali- (MWD) FERRIS Perris a miles in length fornia DAM AND LAKE miles east of Los Angeles. Perris, the nearest town, is 5 miles to the southwest (Figures 278 and 279). The reach of the State Water Project terminating at the Lake is designated the Santa Ana Division. about A and an open-channel ungated spilldischarged into Lake Perris by an summary of Perris Dam and Lake Pershown in Table 35, and the area-capacity curves shown on Figure 280. statistical ris is are m « Figure 279. Aeriol View — Perris Dam and Lake Perris 339 , Purpose Lake Perris, major feature of the State Water Project, is a multiple-purpose facility with provisions for water supply, recreation, and fish and wildlife enhancement. a Chronology Prior to 1965, the capacity of Lake Perris was set at 100,000 acre-feet. At that time, this storage volume the only water satisfied the requirements of contractor taking deliveries from this facility. The Metropolitan Water District studies in 1965 of water service expansion concluded that increasing the MWD, capacity of Lake Perris would increase the security of service and improve flow regulation. The Department to of Water Resources then was requested by study reservoir enlargement, and two amendments to the water service contract between the Department followed. Amendment No. 4, dated Noand vember 19, 1965, provided that the Department would acquire all lands necessary for a reservoir with a capacity of 500,000 acre-feet and would perform planning and design work which would enable to select the appropriate ultimate reservoir size. Amendment No. 5, dated October 10, 1966, stated that the Dam and appurtenant facilities initially would be constructed to impound 100,000 acre-feet and provisions would be made so that the Dam could be raised, in any number of stages, to impound a maximum of 500,000 acre-feet of water. Final design of the facilities was MWD MWD MWD completed in accordance with Amendment No. TABLE PERRIS 35. 5, Statistical and Summary construction of the Dam commenced in October 1970. Increased recreation potential and the adverse impact of reservoir enlargement on the onshore recreation development, along with reevaluation of future demands, resulted in the decision to construct the facilities in one stage with a capacity somewhat above 100,000 acre-feet. Studies immediately following showed that a dam 10 feet higher, providing a storage capacity of 120,000 acre-feet, could be constructed with the funds available. Redesign of the Dam took place in April 1971 and the contractor, who had begun construction but had been limited to working on items unaffected by the enlargement, was given immediate notice to proceed with construction in accordance with the new plans. MWD All construction was completed by February 1974, except for some minor project modifications and initial recreation facilities. Regional Geology and Seismicity The Dam site is located on the Perris block, a large down-dropped block of Cretaceous granitic rock which contains some schist and gneiss. During earlier times, these crystalline rocks were sculptured into ridges and valleys by erosional processes. Later, the Perris block dropped down, changing the drainage pattern and filling the valleys with alluvium. Today, only the higher former ridges protrude through the alluvial surface forming a landscape of flat valleys and low ridges. of Perris Dam and Lake Perris DAM SPILLWAY Type: Zoned earthfiU Type: Ungated ogee crest with concrete baffled chute and riprapped channel Crest elevation.. Crest width. Crest length 1,600 feet 40 feet 11,600 feet Streambed elevation at dam Lowest foundation elevation axis 1,480 feet 1,472 feet Crest elevation. Crest length Maximum probable flood inflow Peak routed outflow Maximum Structural height above foundation Embankment volume surface elevation 128 feet 20,000,000 cubic yards Freeboard above spillway crest Freeboard, maximum operating surface Freeboard, maximum probable flood. 10 feet 12 feet 5.8 feet Dead pool storage 17,500 cubic feet per second 320 cubic feet per second 1,594.4 feet 1 4 ll 'Bj Hh, INLET WORKS wl Buried 8-foot - 6-inch concrete pipeline from terminus of Santa Ana Valley Pipeline above right abutment energy dissipated by hydraulic jump inside pipeline 469 cubic feet per second Capacity — !i I OUTLET WORKS LAKE PERRIS Storage at spillway crest elevation Maximum operating storage Minimum operating storage 1,590 feet 16 feet ,452 acre-feet 126,841 acre-feet 37,013 acrc-fect 4,100 acre-feet 1 31 6-inch-diameter lined tunnel under with a steel delivery manifold Type: 12-foot - Intake structure: Five-level vertical left abutment, tower with 72-inch shutoff butterfly valves Maximum operating surface elevation Minimum operating surface elevation Dead pool surface elevation Shoreline, spillway crest elevation Surface area, spillway crest elevation Surface area, maximum operating elevation.. Surface area, minimum operating elevation. 340 1,588 feet 1,540 feet 1,500 feet Control: Regulation of flow at delivery manifold by water users 1,000 cubic feet per second Design delivery 10 2,318 2,292 1,540 UlowofT structure: 6-foot-wide by 12-foot-high slide gate downstream of delivery manifold with bolted bulkhead at downstream; terminus ,; '.Wi 3,800 cubic feet per second _ Capacity miles acres acres acres ! ' SURFACE AREA - ACRES 2800 2400 2000 600 200 800 400 0 1600 1560 u. I 9 540 .1 1520 500 I480 20 40 60 BO 00 20 140 160 CAPACITY ACRE FEET Figure 280. Area-Capacity Curves The Dam is located in one of the most active seismic Design nareas in Southern California. There are seven faults within 20 miles of the site which have been classified Dam as active. These faults are: San Andreas; San Jacinto; Description. Perris Dam has a zoned earthfill sec- Elsinore; Agua Caliente; and the Casa Loma, Loma I Linda, and Hot Springs branches of the San Jacinto. {The southwest margin of the San Jacinto fault zone is ithe Casa Loma fault, which is within 6 miles of the Dam site and 1 mile from the edge of Lake Perris. The Elsinore fault zone is located approximately 17 miles southwest of the Dam site. I During the 33 years of available seismograph records, 31 earthquakes with Richter magnitudes of 3.0 to 3.9 were recorded within a 10?mile radius of the . Dam site, and 15 were recorded with magnitudes over 4.0 within a 30-mile radius of the site. Two of the earthquakes, within a 20-mile radius, were of major lproportions, with magnitudes of 6.0 and 6.9. One of these occurred in 1918; its epicenter was only 16 miles southeast of the Dam site. Buildings and water mains in the town of San Jacinto were destroyed. tion with a sloping clay core (Figure 281). Except for short reaches on the left abutment and at the rock outcrops, the Dam is founded on an alluvial founda- tion. Necessary freeboard to prevent overtopping of the Dam during maximum flood was computed assuming a maximum wave height plus run-up caused by a wind of 100 miles per hour. The dam crest thus was estab- lished at elevation 1,600 feet. This provides a free- board of 12 feet above normal pool. The maximum section (Figure 282) is 128 feet high. The dam alignment was initially predicated on the ultimate development (500,000-acre-foot lake). Left abutment location was selected to yield the most fa- vorable rock contact for the large dam, even though considerable shaping was required for the lower por- tion. The rock outcrops at the valley center were used 341 342 Figure 281. Embonkmen? Plan um? I: II Ia: glans I In? In nun nunup". In nun [unvu-n mu I 5.1 hp r-Il' Inn-unna- innunuu- . m: nun" nun Innwnunu Inn-n I um nu Innwnrau tum" ant-upuu-I In 1., V1. H- Inn" mu mun: nu mun-I In In r-lM-I <8 ""1va "(In 5? In r-IaI-a It'll/lu- lIIhgr - I .urI unwr? Nauru/II dump" . In . Umrl or uu-rn -. an": - run-n I run I Mun: rI tun-unm- I mm mm um": SAFETY - .- Dbl?1y .- Inn-u..? gourmet-"um uvu nun" ?man-u "an? nu pluma- DAI AID LAll GENERAL PLAN 0?!ng 44. 04 -z 25?87401 343 u, Figure 282. Embankment Secfi0ns nu nanny/g (Ill! 2 Illa ?Man Ina Ilan IUD .4 arl'mol pound Iun Hunt! ll nu hr; lid SECTION Sena.- tr!" am am 0., v-tlI-l in nu I [nu grunt Iin Illa 131 . I \4 Dr/ymll pound mu ?f,flmal(1 mu ?an (JED SECTION AT STA 64 0 50 lulu 10? Aland-tor mun Ann M: I Dun Au: su mu?: A (on. I cut Inn-1m? 4., run?: Iona qu-h um, mun mu? \4 0H,Inal ?raund mu human: run Ilu ?gf?m? Iz?lurauud (rain _m SECTION AT STA. 24'00 (call la' NOYII Nor/"mini ("In hallo-u I cum MumIn'l I?vtl ?um cum All BIVIMOI nuns on: Ann LAKE EMBANKMENT SECYIONS turning point, and the right-leg alignment followed the shortest line to topography of sufficient elevation. Because embankment construction was underway when the decision was made to change the reservoir capacity, the alignment described earlier in this chapter was not changed. as a The core of the Dam is constructed of a plastic clay, and the outer zones are composed of silty sand. The downstream silty sand zone contains a vertical crushed-rock drain, and a horizontal drain underlies the downstream shell. A filter zone of silty sand was placed between the core and the vertical drain. Embankment zones were made a minimum of 12 feet in width to allow efficient placement and compaction. Riprap protects the upstream face of the Dam from wave erosion. Riprap at the downstream toe also protects the exposed face of the horizontal drain. The remainder of the downstream slope was planted with a stand of grass for surface runoff protection. Slip circle and sliding wedge Stability Analysis. analyses were made to determine the stability of the embankment under all anticipated loading conditions. Satisfactory safety factors were attained for the section as designed. Critical loading cases were: upstream slope, reservoir at critical level and earthquake load; and downstream slope, full reservoir with earthquake load. Earthquake loading utilized in these analyses was assumed to be a horizontal acceleration of the foundation in the direction of instability of the soil mass being analyzed. The assumed acceleration was 0.1 5g. Material strengths utilized in these analyses were derived as follows: Zones 1 and 2 and foundation, soil testing by the Department; and Zones 3 and 4, estimates based on material strengths determined for similar materials (Table 36). Dynamic element analyses were made by the University of California and a private engineering firm. These analyses showed that the Dam was stable under severe earthquake shaking and that substantial increased stability could be gained by achieving high density in Zone 2 material. Therefore, compaction near the maximum department laboratory standard finite was required for this material. Settlement. Analyses were made for the Dam and alluvial foundation to estimate the additional amount of embankment required to compensate for settlement during construction and to establish the crest camber necessary to compensate for postconstruction settlement. Anticipated settlement of the embankment during construction was calculated by summing consolidation as horizontal layers were placed successively. This was found to be 2.4 feet. Postconstruction settlement occurs mostly in the foundation when saturation takes place. The settlement was estimated to be 3.6 feet. The 4-foot camber supplied at maximum section was a summation of the anticipated postconstruction settlement of the embankment and the foundation. Construction Materials. The sloping impervious obtained from 5 miles northeast of the Dam site. Investigation was made of ways to furnish water to this borrow area after construction to provide a fishing and waterfowl observation site. Lack of funding by potential operating agencies and possible conflicts with the main recreation area resulted in abandonment of this concept. Therefore, the borrow area was designed as a free-draining excavation with flat slopes so the land could be returned to its original use of grain farming. Zone 2, the semipervious upstream and down- core (Zone 1) a borrow area is a plastic clay material stream shells and downstream dam facing, was obtained from a borrow area within the lake area and from required structural excavations. Two alternative borrow areas were considered. The first was located Dam and was formed by as close as possible to the simple excavation lines. The second contemplated excavations along the north shore for recreational enhancement. Slopes for beaches and boating facilities along with peninsulas formed of waste materials were provided in the final configuration of the borrow area. This alternative was requested by the Department of Parks and Recreation and general layout criteria were furnished by them. As the second borrow alternative — obviously would be more costly, each was included in the specifications on separate schedules, and potential contractors were required to bid on each. The Department then could award the contract on the basis of either schedule, depending upon the differential cost and availability of funds. The horizontal and vertical embankment drains are composed of a clean drain rock (Zone 4) enveloped by sandy gravel transitions (Zone 3). Originally, it was planned that Zone 3 and 4 material and riprap would either be quarried and crushed granitic rock obtained from the ridge near the left abutment of the Dam or hauled from designated sources outside the project area. The materials investigation revealed insufficient quantities of clean gravels within reasonable haul distance of the site and demonstrated that crushed rock would be the most economical alternative. The gradation of Zone 3 material was established on the basis of the Terzagi filter criteria with respect to the gradation of Zone 2 (silty sand) and Zone 4 materials. An on-site quarry was established as the source for riprap. Average rock size required for riprap was 170 pounds, ranging from 20 to 2,000 pounds. The horizontal width of the riprap layer was established at 10 feet. Crushed rock bedding was provided beneath the riprap for a transition to the fine-grained underlying material. A width of 12 feet satisfied the thickness requirements and allowed room embankment minimum for efficient placement and compaction. ltd I The main portion of the foundation for Perris Dam is alluvium within a broad valley between two granitic ranges, Bernasconi Hills and Russell Mountains. The alluvium, consisting of a mixture of silty sand and clayey sand, is deposited over granitic bedrock. A layer of decomposed granite, up to 60 feet in thickness, overlies much of the intact bedrock. The alluvial foundation is divided by granite outcrops near the central region of the site. North of the outcrops, the alluvium is relatively shallow, averaging less than 40 feet. South of the outcrops, the bedrock dips forming a subsurface canyon, and the maximum alluvium depth is over 250 feet. The left abutment of the Dam is granitic rock of the Bernasconi Hills, whereas the right is formed by rising alluvial ground surface. The embankment is founded on rock in the vicinity of the outcrops. Foundation. provided at Perris Dam to monitor embankment and foundation settlement, internal pore pressures, and response of the embankment and foundation to ground motions from earthquakes (Figure 283). Facilities at the site are consistent with those provided at other project dams; however, portions of the instrumentation system are somewhat more elaborate because of the unusual foundation conditions. Control panels for monitoring instrumentation are located in two terminal buildings. Instrumentation and other features of the performance monitoring sysInstrumentation. Instrumentation is tem for the Dam TABLE 37. and Lake are described Table 37. Features of Performance Monitoring System Perris 1. in Dam and Lake horizontal movement Lake Perris net: Total of 13 instrument stands. 2. Level line: 25 miles of bench marks around Lake; 3. Lake-level gauge. 4. Embankment and 5. 6. 1 kilometer spacing. foundation instrumentation: 24 piezometers. 27 crest settlement monuments. 5 accelerometers; crest of dam, on foundation below crest, near the rock-alluvium contact 77 feet below the embankment, in alluvium downstream of the Dam, and in rock outcrop downstream of the Dam. 2 cross-arm settlement devices. Seismographs: 1 instrument located at Instrumentation Terminal No. 1 instrument installed on the dam crest. 1. Open-tube piezometers: 13 cased holes downstream of Dam. Inlet Works Description. An S'/j-foot-inside-diameter inlet pipeline joins the Santa Ana Valley Pipeline at vent structure No. 1 on the crest of the hill near the right abutPerris Dam (Figure 284). The inlet pipeline, located in a cut section, descends 190 feet in elevation. Ninety feet of drop occurs in the first 400 feet of length. It then rises slightly over the next 670 feet before descending at vent structure No. 2 over the ment of final 2,630 feet to the terminus at the outfall basin. located beneath the and is protected by a 30-foot-wide concrete apron extending beyond the end of pipe on a 2:1 The outfall basin structure is lake surface slope. A terminal stilling basin, 70 feet wide, 150 feet and 35 feet deep, was provided to minimize churning of silt into the Lake by water jet. Because the inlet works is located near a recreation area, the selected design was based on maximum safety and minimum adverse environmental effects on the surrounding area. During the preliminary design stage, three alternatives were investigated. Two openchute alternatives with high-velocity flow were elimilong, nated for public safety reasons. The high-velocity buried pipeline alternative best satisfied the above considerations at a feasible cost. Hydraulics. The inlet works was designed to sattwo hydraulic requirements for conveying project water. The first requirement was a summit invert elevation of 1,698 feet. This elevation provides sufficient static head to achieve the required flow at upstream turnouts on the Santa Ana Valley Pipeline. The secisfy ond requirement was a maximum sizing the inlet works to convey flow of 560 cubic feet per second (cfs) into the reservoir. 345 346 Figure 283. Embankment Instrumentation nun/m In )4 rum; ?00, (gr rlmg?or 6567/ a/v hm A N'f fl Dun All. . .0. our Ina . nun, SECTION 41' STATION 52?05 lnu- (InJun-1'. lm' I 0110 All! not", a . I I. re InllrumuIF-?on Yulm' . Na 1 A SECTION AT 55?75 in? 50? a 50' I?covlor'maftr pul. [up 51?1" ?00 //Imrul nu: l-l-nlA-I rm-I an? r? nu/uagngn and Al. A 1 ant 1 I ubra enough coon- tho (In I'll loop 1. rice]! arcs; {?1anle In 9. . as" Nell 1? Martyn-mung:- rummal No I aunt? Iva-Kt mnx: EICAVATION A ltreltmm'hr and otN/trograph coo/'0 H. 7: m- kmizr? {hf-T ml?? A 9 AI 0 Emu/mum; mun-nu; Acclluanulor (?law-l ~01: ?aura (M munwu?? ?new" mm or II: cl. lama mung-Am mu a- trough 9n 14-"me pm ,nle 'mbankmenfrut SAFETY - - N?cy - WATER 0' I?m moo-cu av nano- sun nun ununu mutant: INSTRUMENTATION VLAN AND SECWONS SECTION Inlamam?MW? -m I. m. ?ya-53.. 347 Fig re 2 84. Inlet Works?Plan and Pro?le 1100 Had no 054? 6 p.144: in" ,nut A ~011r417} (:00 ?are A'M?l?u- In a v- :74: an :TvaA7431 pom 5'17le (~ch If 0w! .1 hr (we) ?o f, :95mac In/u/ Worl- - II. I 0 A NIH Ina-4 r: r- ?4 47;, "5 av; Inn on" mum. sun ANA olvulou PERRIS DAI INLET AND OUTLET WWI INLET PLAN AND PROFILE 0-44). .nucvwn I'll?' wM?L??l?I?l - Ur. ?-Fl uni In! 's-l of the water downstream of the Pipeis dissipated by hydraulic jumps inside the Pipeline. The profile grade was selected to prevent the jump from being swept out. The Pipeline from the blowback due to air entrainment jump. Vents are provided at locations where pipe flow changes from full to partially full. Because the maximum velocity is in excess of 60 feet per second, 2 inches of concrete cover over the inside reinforcement was selected for protection against abrasion. The pipe joints were beveled to minimize The seismic forces on the concrete shell of the tower include lateral inertial forces due to dead load and lateral dynamic forces due to two cylinders of water with diameters equal to the inside and outside diameters of the tower. The earthquake input was 60% of the San Andreas design earthquake acceleration spectrum, as recommended by the Department's Consulting Board for Earthquake Analysis. This design spectrum suggests a horizontal acceleration of onehalf gravity for rigid structures. The input was reduced because foundation conditions, including fairly intact rock, were considered better than those for which the design earthquake was developed. Two percent of critical damping was used. The moments and shears used for design were calculated by means of an elastic model analysis. Final design moments and shears were determined by computing the root-mean-square values of the moments and shears generated in the first five modes of vibration. The tower, because of its moderate height, is a relatively rigid structure with a first mode period of 0.33 of a second. For this reason, the higher modes do not contribute significantly to the seismic loading. Inelastic yielding, in the event that the design earth- The energy line was summit partially sized to prevent induced at the cavitation. Pipe Design. Structural A low-pressure (43 pounds per square inch) reinforced-concrete pipe was selected to resist internal hydrostatic pressure due to the hydraulic jump and to support 20 feet of earth cover. Outlet Works The outlet works Description. abutment of the vertical, is located at the left Dam and consists of a multiple-level, intake tower; concrete and steel-lined tunnel; and concrete-encased, steel-pipe, delivery facilities delivery facilities connect to the water user's distribution facilities and provide a gated outlet to the downstream channel. Control and monitoring of the outlet works take place primarily from (Figure 285). The a control building jointly used by the Department and MWD. Intake Channel. Outlet Works Tower. The cylindrical, reinforcedconcrete, outlet works tower with a 26-foot inside diameter is 105 feet high above foundation elevation and is capped by a deck supporting a 20-ton gantry crane (Figure 286). The tower contains 10, hydraulically operated, 72-inch, butterfly valves which release water to the outlet works tunnel from five selected levels within the reservoir, two valves per level. The quality of water released can be selected. Two tiers of valves (four valves) at the selected withdrawal depth are opened for delivery at the maximum rate (1,000 cfs). Steel cylindrical hoods on the discharge end of the eight upper valves direct the flow downward. Directing the flow downward minimizes the possibility of entrainment and damage to downstream compo- nents of the outlet works. Hoods are not provided for the lower valves as no change in flow direction occurs between the valve and tunnel. A movable fish screen outside of the operating intake valves excludes small debris and fish from the system. The tower was designed to resist stresses resulting 348 is exceeded, probably would be confined to one hinge area at the base of the tower. The outlet works tower footing was designed to transfer all superstructure loads into the foundation rock by means of a spread footing anchored to the quake The purpose of the intake channel is to convey reservoir water to the outlet works tower when the reservoir water surface elevation drops below the original ground surface at the tower site. The channel has a trapezoidal cross section 40 feet wide at the bottom with 4:1 and 3:1 side slopes and is partially lined with impervious earth blanket. air vertical dead load and the effect of seismic forces with full reservoir conditions. For the dynamic analyses, the tower was assumed to act as a vertical cantilever fixed at the base. rock. It was assumed that the footing would receive the shears from the superstructure shell above and transfer them to the rock mass below, primarily by its shear resistance. The compressive stresses are transferred to the rock in direct bearing since the footing concrete was placed against an undisturbed rock surface. The tensile stresses due to overturning are transferred by the anchor bars into the rock mass. moment which are grouted Access to the tower is provided by a 109/^-foot-long 16-foot-wide bridge from the outlet works access road. This road follows the south lake shore to Bernasconi Pass and then connects to Ramona Expressway. The bridge was designed for HS 20-44 loading. Outlet Works Tower Mechanical Installation. Ten 72-inch-diameter, rubber-seated, butterfly valves were installed in the intake tower in two vertical rows. The port valves can be operated locally from the control cabinet on the tower operating deck and remotely from the joint MWD-Department control building. The valves are intended to operate in the fully open or closed positions. Each of the valves in one vertical row, however, at differential is capable of operating partially opened heads_of up to 93 feet and discharging free flows t [1 r. t j ; 5, „( up to 60 cfs for filling the tower. Each valve is actuated by its own hydraulic motor and screw drive-type operator. The valve operators are capable of opening or closing the valves under a maximum differential head of 30 feet and closing unfull reservoir head. The hydraulic system for operating the valves consists of two vane-type oil pumps; an oil reservoir; solenoid-operated, 4-way, control valves; flow control valves; strainers; piping; valves; der and appurtenances. The system was designed to operate with a maximum hydraulic oil pressure of 2,000 psi and operating time of 5 minutes per valve stroke. Two valves can be operated simultaneously. A structural-steel maintenance platform stored in the tower above normal reservoir level is provided for servicing the upper four tiers of valves. The lower valve tier at elevation 1,503 feet is serviced from the tower base at elevation 1,495 feet. One trolley of the 20-ton gantry crane raises and lowers the maintenance platform on stainless-steel guides embedded in the tower wall. The platform was not designed to support the weight of the valves, operators, or hoods. These items must be removed from the tower during disassembly by the gantry crane. A bulkhead gate is provided for closure of the butterfly valve intake openings to facilitate repair or removal of the butterfly valves. It is 9 feet - 4 inches high by 9 feet - 5'/ inches wide and weighs approximately 9,000 pounds. The bulkhead is stored off the tower in the on-site maintenance facility. The gate, with lifting beam attached, is lowered vertically into slots on the outside of the tower by one of the 10-ton trolleys on the 20-ton gantry crane and dogged in front of the valve opening to be closed. A 20-ton-capacity, electric, cab-operated, outdoor, was installed on the tower traveling, gantry crane The crane rails anchored to the equipped with two 10-ton-capacity trolleys which service both the inside and outside of deck. tower deck and operates on is the tower. The crane also is used to provide hoist service as necessary on the tower deck and inside the tower and to position the fish screens. Capacities and speeds are as follows: 20 Rated capacity of crane, tons Number of trolleys Rated capacity each trolley, tons Length of lift, feet Length of travel, feet Hoist speed, feet per minute (fpm) Trolley travel speed, fpm Gantry travel speed, fpm 2 10 125 13 .. 14-20 4—6 4-6 Master control devices for the functions of the crane were installed on the console in the operator's cab. Stainless-steel wire rope is used on the crane hoists since operation of the fish screens requires submerged service for extended periods of time. Screens to cover operating intake ports are provided to prevent passage of fish and debris into the delivery system. The screens are '/j-inch-square mesh covering One frame is suspended by the gantry crane over two operating valve tiers for each of the vertical valve rows. Rails are provided on the outside of the tower for guidance during up and down movement and for holding the screens horizontally in structural-steel frames. place. A washing system designed to remove minor debris and algae from the fish screens is provided in the intake tower. Two washing stations, one for each fish screen, are located at elevation 1,591 feet. variable-spray-pattern wash nozzle is mounted on a flexible ball joint at each platform. Water to the A washing stations vertical, turbine is supplied by a six-stage, deep-well, pump mounted at elevation 1,600 has a rated capacity of 90 gallons per minute at a total head of 265 feet and a speed of 3,450 feet. The pump rpm. Outlet Works Tunnel. The works tunnel is pressure conduit about 2,100 feet long, located in the left abutment of the Dam (Figure 285). It conveys water from the outlet works tower to the delivery facilities which serve (Figure 287). The tunnel was provided with a reinforced-concrete lining upstream of the axis of the dam impervious core. From the core axis to the downstream portal, steel liner with concrete backfill was used. The steel liner was designed to withstand external pressure due to ground water equal to the depth of cover over the tunnel or to elevation 1,590 feet, whichever was greater. A study of types of liner plate indicated that, due to the greater stiffener spacing A572 steel was the most possible, the use of economical. Liner thickness was set at J^ of an inch so as to adequately withstand the entire internal hydrostatic pressure to elevation 1,590 feet and to provide a outlet 12-foot -6-inch-inside-diameter MWD ASTM rigidity for handling. The reinforced-concrete lining upstream of the axis of the impervious core was designed to withstand external hydrostatic head due to reservoir water surface at elevation 1,590 feet. The section reinforcement was designed to withstand the entire internal pressure, with the hydraulic gradeline at the same elevation. An overstress of 25% was allowed for transient overpressure loading. A nominal lining thickness of 18 inches was used for most of the tunnel. Outlet Works Delivery Facility. The delivery facility is located adjacent to and below the left abutment and delivers water to MWD's Ferris control facility (Figure 287). The delivery facility consists of a 12-foot - 6-inchsteel conduit extending from the west portal of the outlet works tunnel to a 12-foot - 6-inch-insidediameter (ID) service outlet manifold, a service outlet manifold, three branch lines extending from the mani- diameter 349 -E. Wu:? H. .. ennu- Gin?i q-wso "My 014. I. a .. ONV NV?ld sun: unno nuo- mum on sunmomma; IHVM ALIJVS ir-n "v "If for Au 45" pa: w/j'pvuwdq m] a] I ?nun-:vau/ 4.0 'f [mama (1+1 art I apt, Outlet Works?Plan and Pro?le Figure 285. 350 z/lv [600-0 cann- craru ml ahawn an wg 0.7-: 98' q'ms me} 1600 a "Uh Icrlan 07.9mm ground hr? 1 Fan lei-(n rolutmn wall - an deri- 435 aa~4 ELEVATION Figure 286. Ou?lel Works Tower 0 59? PROFILE GRADE Luvt/ A vain hand 4 mn abou' Ma [Inc A Barrmr Hallmg 7 I Mad-fad mum?! Candulin 472?: Fluh [cf-In Angkor bar. SECTION 5 5 SECTION A - ,4 Seal. #3 . I Seal. Dun-rialr nag. stanon 1 awg v- -5 GENERAL NOTES [In/nu mum-id mum. 0mm 11/ uncut: And "mi 41ml: n; can/arm ta mm? (my rm: Jp'ci?clhen? A, ma mm! Eme-g 0mm? of "a Carulruchon 0 Tank 5.. Much Dug: pp. .0 dull dram. to for augu- .u v-4so-7 3?00 our 5w ?1 Walking Pf'I?arm ,a 1114 alum." Cunard! Caner-h f? - 400a m: f, - All Mal! planad 2' [Mr Ira/v1 ?Mn. cf Ifructur- cvuyvh "4 In?! M: Jar/Incl 9f town ?manta I) . moan in. re - MM ,nn pol-d mm all Earn-r! chow". . may a. local-d a. mamnd ?up! Canllruclran on ppNval ?rms u'll Stew lh'utfura [lull h: 457M drugnnhon 4:5? arr/ll: mm" 5nd,. mun: Mr" 5.. 9w, van-7 lav 4.4 4? . 101114 ?tn?Fur SAFETY - nclu?ll wnuu mum on: 0mm tom TOWER AND ACCESS BRIDGE Ends. Aw. Loading .EI IAL FLA. AID IICTIUII PLAN seat. 10 ?g Ms 351 352 Figure 287. Outlet Works Delivery Facili?es Our/n: 13]! All ~01. I .. we Car?rg/ mg. ml" ?1 "mm" z, 55. Hannah} Iv no 7; o, 149.5140?\agr w: [111m - ll"! ur Oran 'Is a u? mg [Ml In}: IMO en?ml/ ya?: 1 01,1! - 5 4;;utl Ann" I . ?1 aqua: 00 I, am, 1.40 FROFILE rum" n? nun-Mu so (5/0 ?to It 70 TVIJICAL SECTION yum: on mu? won-(so no ounn won-(s ouTLn Ion-(s DELIVERY FACILITIES sn: PLAN and a terminus release gate. The conduit, maniand branch lines are all concrete-encased with the approximate length of conduit and manifold 353 and 141 feet, respectively. The appro.ximate overall lengths of the 4-foot - 6-inch ID branch line and the 6-foot - 6-inch ID branch line are approximately 110 and 88 feet, respectively, measured from the centerline of the service outlet manifold. Each of these lines near the downstream end is equipped with a butterfly valve. The two valves are located in a single valve vault and are accessible through hatch covers. The valves are operated in the fully open or fully closed position only and thus are not used to regulate flow. Regulacontrol facility. tion is accomplished by the The third branch line, a provision for future expansion, has a 7-foot - 6-inch ID and terminates with a fold, fold, MWD dished bulkhead. A blowoff structure was provided at the service manifold terminus to permit emergency evacuation of the Lake. The original design involved a spherical head at the outlet manifold terminus. To remove the head with the pipe full of water would require the use of explosives. Subsequent to the construction period, this evacuation concept was reconsidered and a 6-foot by 12-foot slide gate was provided to increase the flexibility of the system. The maximum discharge through the slide gate is approximately 3,800 cfs. A bolted bulkhead is installed downstream of the gate to ensure that large releases cannot be made inadvertently and to allow for exercising the gate. To I I I i avoid differential settlement, the conduit and manifold were designed to be supported on sound rock. Bedrock of an irregular nature was overexcavated and backfilled with concrete. The 6-foot - 6-inch branch line has a capacity of 325 cfs, and the 4-foot - 6-inch line has a capacity of 175 cfs. The additional stubbed-off branch line provides for a total ultimate capacity of 1,000 cfs. The 12-foot - 6-inch conduit provides a velocity of approximately 8 feet per second (fps) at a discharge of 1,000 cfs. The conduit also provides for a maximum release of 3,800 cfs at 31 fps through the slide gate at reservoir water surface elevation 1,588 feet. Although the tunnel liner and the delivery facility conduits are encased in concrete, the total internal pressure is resisted by the steel conduit. Allowable stress for the maximum load case is 25,000 psi. Maximum internal pressure occurs with hydraulic gradeline at elevation 1,590 feet, plus 25% of the total static head for transient overpressure. Welded joint efficiency was considered to be 100% and all joints were required to be radiographed. The required minimum 28-day strength of the concrete was 3,000 psi. Delivery Facility Mechanical Installation. '• ; One 78-inch-diameter and one 54-inch-diameter valve are located in branch conduits near the interface with facilities of the water contractor (MWD). The valves are housed in a common vault. Each valve is metal- seated with a hydraulic cylinder operator and a common hydraulic control system. Each delivery facility valve was designed for a working water pressure of 50 psi and to withstand a 50-psi differential water pres- sure across the closed valve disc from both the up- stream and downstream direction. Each delivery butterfly valve was designed to withstand opening and closing under the following conditions: Constant alve Size (inches) 54 78 \ Head Upstream of Maximum Flow Maximum Flow During Opening During Closing Valve of Valve (feet) (cfs) 100 175 of Valve 610 100 325 1,280 (cfs) Both valves and their operators primarily were designed for fully open or fully closed operation, but the valves can be closed under emergency conditions, either independently or simultaneously, in approximately 5 minutes. The hydraulic control system was designed for an operating pressure of 2,000 psi and, in order to minimize the cycle time for the oil pumps, a bladder-type hydropneumatic accumulator is used to maintain pressure on the system to keep the valves fully open. Since Perris Dam is located in an active seismic area, a seismic acceleration of 0.5g was used in the design of the valves and their appurtenances. One large dewatering and two small drainage pumps are located in a pump-house structure adjacent to the main outlet works conduit. All three pumps are complete with automatic controls, discharge lines, and appurtenances. The dewatering pump is used for dewatering the main outlet works conduit, and the drainage pumps are used to remove any extraneous water from the valve vault. The dewatering pump is a vertical-shaft single-suction type with a rated capacity of 500 gallons per minute (gpm) at a total head of 30 feet. The drainage pumps are the submersible type with a rated capacity of 10 gpm, each at a rated head of 40 feet. The outlet works release facility slide gate is located downstream of the delivery branches at the end of the delivery conduit. The gate provides a waterway 6 feet by 10 feet. The gate leaf is cast steel, 7.25 feet wide by 12.5 feet high, and weighs approximately 20,000 pounds. The gate is operated by a hydraulic cylinder located on the concrete structure above the gate. Preliminary design considered two gate-leaf alternatives: (1) a welded-steel gate, and (2) the cast-steel gate which finally was selected. Historically, highpressure slide gates of this type have been cast. The basic configuration lends itself to sound casting practices and was found to be less expensive due to the extensive weldments in the alternative design. A hydraulic operator is provided for opening and closing the slide gate. The hydraulic system consists of a hydraulic cylinder and piston rod, pumps, ac- 353 an, ?Mm Ids-.1 77d ao 51? 'ne .7 onv nuoua ?Nna 3X11 S?I?id IBISIAIO nus nmun-nomad - AHJVS 11.7110 ?v??r'vwm 9-9 N0l1035 aw", ?mu/o. .. tum I Inqu- .n van, I u, I In; In Hurts?:2 ,wmn "Vamp I Ian,? 51-? NV 7d lunar, ulna 5.5 owl ~45 ?1 I. us Pol-I u! ?"41 Flu; Inna-4 u; 1.4- .. "5 Mai0/115 04 Nancis ?anally-aw; v-?wa Julul/ n4; yd unpu "punt 4 a4 mum/1, an? 113? um"; us up, [11-44 I. A m? .. a 11?qu 11:Ala/.1715 onloco-a? 015/ 015/ out 21., .3: 055/ I: z/ano an o; 006011/ t: ?unanl Spillway?Plan, Pro?le, and Sections Figure 288. 354 cumulators, and a control cabinet. The cylinder has a 31-inch bore and 146.5-inch stroke. The operator was designed to open the gate under an unbalanced head of 92 feet. The system operates at 1,500 psi and utilizes two pumps to obtain an opening and closing rate of approximately 1 foot per minute. If electrical power to the system is interrupted and emergency operation of the system is required, one pump is designed to receive power from the emergency engine-generator set and operate the hydraulic system. Two oil accumulators precharged with nitrogen are connected to the system to provide holding capacity in the up position. The system was designed for local-manual operation for opening and closing cycles. outlet works control room, located The in the joint control building, contains facilities for controlling and monitoring contract water deliveries to Southern California Edison Company supplies 480volt 3-phase power to the building which is located in close proximity to the delivery facility. The control MWD. room 1. houses: Controls for operating the tower and delivery butterfly valves. 2. Position indicators for MWD butterfly delivery and department valves. Reservoir and tower water surface elevation valves 3. in- dicators. 4. Venturi metering readout equipment. 5. Emergency power supply. Spillway Description. The spillway is located beyond the right dam abutment (Figure 288). 8 50- foot-long, unlined, trapezoidal, It consists of an approach channel 22 feet wide; a reinforced-concrete control structure; a concrete baffled chute; a short section of riprapped channel; and an unlined channel terminating far enough downstream to eliminate erosion adjacent to the toe of the Dam. The spillway crest elevation is 1,590 feet, a nominal 2 feet above the maximum operating water surface to prevent it from being overtopped by waves. The crest length is 16 feet. When the lake level was raised 10 feet, as discussed earlier in this chapter, no major changes were made in the channel or concrete structure, except for being moved vertically to accommodate the revised pool level and horizontally to best suit the topography. Hydraulics. The spillway was designed for emergency use only because the probability of spilling is extremely remote. Normally, the reservoir will be drawn down during the winter season sufficiently so that the maximum probable flood volume (8,340 acrefeet) can be stored without spilling. If the reservoir can be made to is full at the time of a flood, releases MWD through the outlet works. The sizing of the spillway was based on the requirement that a sustained inflow from the Santa Ana Valley Pipeline of 560 cfs can be discharged without excessive encroachment on the embankment freeboard. This discharge is greater than the routed outflow resulting from an occurrence of the maximum probable flood with full reservoir. The spillway rating curve is shown on Figure 289. Construction Contract Administration General information about the major contracts relating to Perris Dam is shown in Table 38. Perris Dam and its appurtenant structures were constructed under two main contracts. The zoned earth embankment, spillway, and outlet works approach channel were constructed under the first contract (Specification No. 70-25). cost increase shown in Table 38 for Most of the this first contract resulted from the decision to increase the reservoir capacity to 120,000 acre-feet as described earlier in this chapter. The inlet works and outlet works were constructed under the second contract (Specification No. 71-11). Dam Foundation Excavation. Four 6-foot-deep trenches were excavated approximately along the centerline of the Zone 1 embankment at Stations 25 + 00, 40 + 00, 88 + 00, and 105 + 00 to determine if low-density materials or other objectionable materials occurred within the designated excavation limits. Samples were taken from these pits to determine in-place densities and moisture contents and for relative compaction tests. By this process, it was determined that a minimum depth of excavation of I foot for the impervious reservoir blanket upstream of the Dam, 3 feet for Zone 2 embankment, and 6 would be necessary. feet for Zone I embankment the blanket. southerly direction from the right abutment toward the left, with the excavated materials used directly for construction of the reservoir blanket and Zone 2. During these operations, the waste strip was constructed at the downstream dam toe, as called for on the plans. A trench was excavated along the center of the Zone 1 foundation, primarily for further exploratory purposes. This trench extended below the general Zone a Perris Specification Low bid amount Final contract cost Total cost-change orders Starting date 10/10/70 11/15/72 Perris Dam Constructors 356 and Perris 70-25 $27,394,995 231,362,749 222,537,778' Completion date Prime contractor Reflects bid-price adjustments. Includes 32,260,925 (or recreational of November 1974. Zone 1. A small volume of rock also was excavated along the toe of the dam embankment in the vicinof Station 64 + 00. After it was decided to increase the reservoir capacity, it was determined that further rock excavation would not be necessary in this loca- downstream tion. facilitic The grouting plan for Perris Dam sisted of a single line of curtain grout holes con- on an alignment starting 260 feet upstream of Station 120 + 00 and extending approximately 750 feet to the crest of the Dam at the left abutment. Due to the steeply dipping joints in the bedrock, the holes were drilled at an angle of 60 degrees from the horizontal. At Station 127+00, the curtain alignment angled to the east and extended up the rock face of the left abutment foundation to elevation 1,600 feet. Split-spacing Major Contracts Dam Lake As The left abutment, which is on a granitic rock formation, required shaping and grouting. About 70,000 cubic yards of solid rock was excavated between Station 120 + 00 and the extreme left end of the Dam. Drilling and blasting were required for foundation excavation. Material removed beyond Station 122+00 was hauled from the embankment foundation to mandatory waste area No. 2. Rock excavation beyond Station 122 + 00 extended as much as 40 feet below original ground. Most of the excavation was required for shaping the foundation surface of the impervious — TABLE 38. * al. Grouting. Excavation proceeded generally in ' During the geologic exploration for Perris Dam, three 40-foot-deep trenches were excavated by dragline beneath the dam foundation and later filled with loose material. These had to be reexcavated, and the material was replaced with compacted Zone 2 materi- ity Excavation began in the blanket area near the right abutment. The first materials excavated were stockpiled in mandatory waste area No. I for later use in ' 1 foundation elevation, had a bottom width of 1 5 feet, and had a minimum depth of 10 feet, except where rock was encountered. At Station 90 + 00, sand lenses were encountered, and the depth of the trench was increased to 25 feet. Between Stations 24 + 00 and 27 + 00, an ancient streambed consisting of permeable clean sand was encountered and the trench was deepened about 20 feet. This trench, backfilled with Zone 1 material, forms a partial cutoff beneath the Dam. Perris Perris Dam Dam Inlet and Outlet Works 71-11 26,974,810 27,197,504 2176,919 10/13/71 10/6/73 Dam Perris structors Con- Completion of Perris and Lake Perris Dam Completion Contract No. 2 74-39 2231,169 2254,000 73-01 $2,051,552 22,608,6372 2260,847 3/29/73 2/1/74 Perris Dam Con- (Est.) 9/5/74 12/74 (Est.) Jesse Hubbs & Sons 357 wry-.1? run ?an de warm? .9 3x71 nva snuuad numm saun nus I 0 Wmm?owlum 1 cannon! A0 ?Qumran 5 Ann-v 1 mnuvu If? lilV/A'W' 2, "mmunis]: .. 1 m. u: nm lg( p?v?P?v? ann- cool cool cool 0 ya. 9} 3W f0Anna 7 \Jm-omn manna 0'13937 an: v.7" I \x 1 mm ?aux-?rpm: 3m ?1 7 nu Anna4:11: um I ml in! up. Anyway": 00a 1. (.71er 13414 nu ma -, I 4/1/ A . I mu ?7 5mm-) pm 4373/ 5 [5d ain't): I 9:1 6 (a 5mm" u" I x?L ion of Borrow Areas and Perris Dam Site Locat Figure 290. grouting techniques were used, and the final hole spacing was 10 feet. A grout cap was not employed, and the amount of grout injected was very small because of the tightness of the rock. Most of the grout take was due to shallow fissures in Zone foundation; however, two intervals of high take were encountered at Station 120 + 00 and from Stations 124 + 80 to 125 + 60. It was estimated that 8,600 cubic feet of grout would be needed, but only 1,429 cubic feet were actu1 ally required. Along the extreme left abutment, a rather deep fissure was encountered in the rock extending up the abutment to the full height of the embankment. This fissure contained broken rock and rubble that would have allowed the passage of surface water from the slopes above the left abutment down through the rock drain materials into the dam foundation. To prevent this, a concrete plug was placed against the rock contact line in the fissure at approximate elevation 1,595 feet, and a gunited surface ditch was constructed across the crest of the Dam at the extreme left abutment. Handling of Borrow Materials Clay Borrow Area. To obtain the estimated 8,670,000 cubic yards of Zone 1 material required for the Dam as originally designed, an excavation pattern was established having a maximum excavated depth of about 40 feet with provisions for draining the entire By contract change order, the estimated amount of required Zone material was reduced to 4,690,000 area. 1 cubic yards. Because the original surface area of the site available to the contractor was not changed, the required depth of excavation was reduced drastically. The clay borrow area (Figure 290) was located in a lake area subject to inundation during periods of heavy rainfall, but rainfall during the construction period was small and did not interfere with borrow operations. Advance moisture conditioning, when necessary, was accomplished by a sprinkler system. Clay borrow was excavated with a tractor-mounted l)elt loader (Figure 291) and hauled directly to the Dam using 100- to 150-ton-capacity bottom-dump Figure 292 trucks. Due n Lake Borrow Area to the presence of material in the clay borrow area which contained excessive amounts of silt and sand unsuitable for Zone 1 embankment, the final configuration of this borrow area was somewhat irregular in shape. It was shaped, however, to drain with maximum slopes of 10:1. Topsoil material was stripped from the borrow, stockpiled around the outer perimeter, and replaced on the excavated surfaces after completion of construction. Lake Borrow Area. Two alternative lake borrow plans (within the reservoir area) were included in the contract specifications and each required separate bids. One alternative utilized a simple geometric pattern for excavation in the reservoir close to the Dam and the other required a more complex excavation configuration for the recreation development along the north reservoir margin. Although the borrow associated with the recreation plan was bid slightly higher, the amount was well within the facility allocation and therefore the contract was awarded on the basis of that alternative. Zone 2 material was obtained from the lake borrow area which extends along the northerly shoreline a distance of approximately 4 miles. The shoreline was excavated in a series of coves and fingers of land to provide maximum potential for recreation. Excavation was accomplished with the same type of equif)ment as was used in the clay borrow area (Figure 292). Figure 291. Excavation in Clay Borrow An The original contract provided for stripping of all vegetative matter from the borrow area and placing it upon the fingers of land which were mandatory waste areas. No provisions were made for ultimate development of these waste areas, and the strippings as placed did not bring them above the originally contemplated high water line. When the reservoir capacity was increased from 100,000 to 120,000 acre-feet, provisions were made to relocate this shoreline to conform to the corresponding higher water surface. At the request of the Department of Parks and Recreation, sufficient material was excavated from the lake borrow area to 358 J Embankment Construction The Dam was constructed in a series of three reaches. Embankment construction began at the lowalong the foundation in the vicinity of StaWhen the grouting was completed at the left abutment, efforts were concentrated in that area. Embankment construction then proceeded with a slight slope toward the north to enable loaded trucks to climb to the higher area where embankment was being placed. General embankment construction activity is shown on Figure 294. est point tion 85-f 00. Dam from the crest down was faced with a layer of riprap 10 feet in horizontal width underlain by a layer of Zone 4 bedding material 12 feet in horizontal width. Riprap and bedding were placed continuously as the other embankment zones were placed. To reduce congestion, ramps were constructed down the upstream face of the Dam for use by empty trucks. These ramps consisted of Zone 4 material placed upon the riprap blanket and overlain with Zone 3 material. Zone 3 material was removed upon completion of each section but Zone 4 material was allowed to remain. A layer of riprap also was placed along the downstream The upstream face of the to elevation 1,540 feet Figure 293. Rock Productic place the mandatory waste areas above the normal lake level and provide for maximum recreational use. The embankment drain system consists of 1.3 million cubic yards of coarse material (Zone 4) of 6-inch maximum size and 1.5 million cubic yards of transition material (Zone 3) of I'/j-inch maximum size. Ap- proximately 240,000 cubic yards of riprap was used for slope protection, upstream and downstream. All of the above materials, with the exception of approximately 14,000 cubic yards of Zone 3 material, were obtained from the designated rock source located upstream of the left abutment of the Dam. The rock source was laid out on benched faces ex- tending from a maximum elevation of approximately 2,070 feet to the lowest level at approximate elevation 1,665 feet. The height of the faces varied from 50 feet The rock was blasted from the quarry and hauled to the nearby rock-crushing plant located east of the quarry (Figure 293). Initially, an excessive amount of fines were produced, due mainly to overburden contamination and excessive blasting. Plant operations were revised to to 30 feet. separate these fines. Coordination of the placement of Zones 1 and 2 with Zones 3 and 4 initially was deficient because the loading and hauling equipment used was capable of Zone toe of the Dam above the toe drain. A layer of topsoil, having a horizontal thickness of 12 feet, was to have been placed on the downstream face of the Dam above the riprap. It was anticipated that this material would be stripped from the dam foundation and stockpiled. Because there was little vegetative matter in this material, it was used in the lower layer of the upstream blanket, and no stockpiling was done. Zone 2 material was used in place of topsoil for the The downstream facing. original design of the embankment provided for a layer of blanket material 3 feet thick extending 1,000 feet upstream from the toe of the embankment. Blanket material was obtained primarily from excavation of the dam foundation and was the first work undertaken. When the decision was made to forego any future material faster than the rockcrushing plant could produce the material for Zones 3 and 4. This lack of coordination resulted in nonuni- placing 1 and 2 form elevations of the various embankment zones dam axis. In an attempt to reestablish uniform zone elevations, the contractor ceased placement of Zones 1 and 2 and purchased supplemental Zone 3 material from an alternate source. However, only 14,000 cubic yards of supplemental Zone 3 material was placed before heavy rains caused that effort to be terminated. The quarry and crusher plant operations were later revamped, and the rate of production of Zone 3 and 4 material increased sufficiently to permit the zone elevations to be regained, and the embankment construction proceeded to completion. transverse to the Figure 294. Embanltment Construction Activity 359 Dam above crest elevation 1,600 the upstream toe no longer was needed for ultimate stability. Elimination of this fillet would have resulted in movement of the enlargement of the feet, the 8:1 embankment fillet at downstream for a considerable distance. By then, however, the work on the blanket had progressed for about four months; thus, no change was made and the blanket was constructed to the original upstream limits. The area between the original and revised upstream toes was covered with Zone 2 material for at toe least a 3-foot depth. The initial problem in producing Zone 3 and 4 material for the horizontal drain in sufficient quantity (previously discussed) created the necessity of constructing Zone 1 and 2 material in lifts approximately 3 feet in height and wide enough to allow for placement and compaction. When the horizontal drain was brought to its maximum required depth, the placement of Zone 1 and 2 material proceeded in a more manner. efficient Zone material was placed in layers not exceeding 6 inches in compacted thickness. Compaction was achieved by 12 passes of a sheepsfoot roller. The initial 12-inch depth of Zone 1 material next to rock foundation was compacted in 4-inch lifts with rubber-tired rollers. The optimum moisture content of this material averaged 14% with an average field dry density of 1 14 pounds per cubic foot. The relative compaction obtained was approximately 98%. Zone 2 material also was placed in layers and compacted to a 6-inch thickness by four passes of a sheepsfoot roller, followed by four passes of a pneumatic roller (Figure 295). The facing and blanket materials were placed and compacted in the same manner as the Zone 2 Two 1 material. were constructed in Zone 2 to determine the compaction characteristics of the materials for the zone. One fill was compacted with 75-ton rubber-tired rollers and the other with 50-ton rollers. Average densities obtained with either roller were test fills within specification requirements. After a further trial period, the 50-ton rollers continued to prove satis- factory and they were used throughout construction. The average compacted dry density of this material was 125.9 pounds per cubic foot, and the average op- timum moisture was 11.2%. averaged 101%. The relative compaction and 4 comprise the horizontal and vertical horizontal drain consists of a lower 3-foot layer of Zone 3 overlain by a 6-foot layer of Zone 4 and topped with another 2 '/2-foot layer of Zone 3 material. Zones drains. The 3 The vertical drain has a reverse slope configuration extending from the upstream end of the horizontal drain to an elevation approximately 12 feet below the dam crest (Figure 281). The drain consists of two 12-foot-wide Zone 3 strips enclosing a 12-foot-wide Zone 4. Zone 3 was placed in layers not exceeding 18 inches compacted thickness with a moisture content not exceeding 5% by weight. It then was rolled with two passes of a vibratory roller weighing over 20,000 pounds, operated at a frequency from 1,100 to 1,500 vibrations per minute. Zone 4 was placed in layers not exceeding 24 inches in compacted thickness and rolled with one pass of the same roller used for Zone 3. The riprap was hauled to the site from the quarry in end-dump trucks. It was dumped directly upon the slopes and placed in final position with a grader. in The design provided for a longitudinal drain trench Dam. The rock drain zones join this toe drain, which consists of a perforated, concrete, drain pipe 12 inches in diameter enveloped with drain rock. at the downstream toe of the The downstream face of the Dam was dromulched immediately after construction to hypre- vent surface erosion; however, the stand of grass obtained by the first winter was insufficient. Fine material eroded from the embankment was deposited in both the toe drain material and the drain pipe, necessitating extensive cleanup. To prevent any recurrence, major revisions were made along the toe of the embankment. Layers of Zone 4 and Zone 3, topped by a paved surface, were placed along the top of the riprap blanket to intercept surface runoff from the slope above. Downdrains carry the water over the toe drain to the original ground beyond. Cleanouts for the perforate toe-drain pipe are provided by 48-inch access wells at 400-foot intervals. Better erosion protection than originally provided by the hydromulching process was supplied by applying straw at the rate of 4 tons per acre and incorporating it into the soil with a roller. Instrumentation previously described (Table 37) installation to completion of construction. Operations and maintenance personnel continue monitoring all instruments. The accelerometers had to be set at a higher than normal triggering threshold during completion of embankment construction because construction equipment set off recording devices. was observed from the time of Figure 295. 360 Pneumatic Roller or. Eu.bankment Zone 2 Mandatory Waste Area No. 2 Mandatory waste area No. 2, located upstream from the left abutment of the Dam, was intended primarily to provide access to the Perris bridge. After it was determined Dam outlet that there tower would be insufficient material wasted in this area to provide the required access, revisions were made to require mini- mum limits of the waste area, which then was filled completely, thus supplementing the waste with material from the lake borrow area. Inlet Works Trench excavation for the inlet pipeline required blasting in areas between Station 1+20 and Station + 90 14 ripper, vation. (Figure 281). A bulldozer, equipped with a and a dragline removed the rock from the excaFor pipe bedding and backfill, the contractor was permitted the option of consolidating (by saturation and vibration) imported free-draining material, consolidating excavated rock after processing for specified gradation, or compacting excavated semi-impervious alluvial materials. The alluvial material was used and backfill was compacted with small, self-propelled, vibrating compactors for the first 6 feet of cover. The remaining backfill was compacted with a sheepsfoot roller. Outlet Works invert was excavated with scrapers on grade for a length of approximately 2,700 feet. The maximum depth of excavation was 40 feet. Three feet of Zone 2 blanket material was placed over the entire excavation surface. Excavated material was placed in the reservoir blanket area. Only a negligible amount of rock excavation was necessary. Two steel girders were set into place with two cranes after being sandblasted and coated with inorganic zinc silicate at the job site. The bridge deck was formed, and three gradelines were set to guide the finishing machine during concrete placement. The channel a level The between elevation 1,495 feet and 1,482 feet was excavated in sound rock by drilling and blasting. The shattered rock was loaded on dump trucks with rock beds and hauled to a mandatory waste area. The 50-foot-diameter tower base was excavated by drilling and blasting with material being removed by a crawler crane equipped with a 5-cubicyard dragline bucket. Material was loaded and hauled away as described in previous paragraphs. The 9-inch holes for the foundation anchor bars were drilled, holes were filled with grout, and No. 18 anchor bars were vibrated into place with a form vibrator. Concrete for the tower base then was placed. The interior form for the tower barrel was erected entire tower basin to full height with the aid of an interior scaffold. The form consisted of a double thickness of plywood backed by wooden strongbacks and metal walers. After the reinforcement steel was erected, port thimbles and valves were securely set in place. The interior Figure 296. Tower Concrete Placement thimbles were supported on pipes set in the previous concrete lift of the barrel. The exterior forms, comprised of a metal shell with Finn forms attached, permitted placements of concrete in 16- and 17-foot lifts (Figure 296). Six lifts were cast (excluding the base and the tower deck) using 1 '/2-inch maximum size aggregate concrete except around the thimbles where %-inch aggregate was used. Forms for the last 5 feet of the tower barrel and the tower deck were prefabricated in the contractor's yard and set on the tower using a crawler crane. Concrete for the intake tower and other structures was produced in a 150-cubic-yard-per-hour-capacity batch plant located near the outlet works. Aggregates were obtained from a commercial source in Riverside. Concrete was moved to the work site in 7-cubic-yard was ap- transporters. Water used to cure the concrete plied by a sprinkling system. Most of the outlet works tunnel was driven through hard, fresh, granitic rock, but some weathered and fractured rock was encountered in the vicinity of the portals. The tunnel was unsupported except for a few steel sets at each portal and a few rock bolts at several places in the tunnel (Figure 297). Ground water did not constitute any problem and only minor seepage was encountered. After holing through, about five weeks were required to remove protruding ribs of rock within the tunnel excavation control line. A concrete subinvert was placed tangent to the control line to facilitate the setting of steel-liner sections and concrete-lining forms. The 40-foot-long steel-liner sections of '/2-inch plate 361 362 Figure 298. Outlet Works Delivery Manifold Figure 299. Concrete Placement in Spillway were longitudinally placed and seam-welded. A con- crete pump was used to place the concrete backfill. A wire-mesh bulkhead was placed at the end of each section to contain the concrete. All tunnel concrete was mixed at the on-site batch plant. Tunnel grouting consisted of contact grouting throughout with additional skin grouting next to the steel liner. Grout was mixed outside of the tunnel. After mixing, the grout was pumped to a hopper in- side the tunnel where it was remixed. From the remix hopper, the grout was pumped into the grout lines. Skin grouting was accomplished through holes drilled in the steel liner. These holes were plugged and welded upon completion of grouting. Due to exceptionally good rock, no consolidation grouting was necessary. Grout curtains were located at Station 36+55 and Station 36+70. Outlet Works Delivery Facility The construction of this facility and associated ap- purtenances was performed in conjunction with other outlet works construction (Figure 298). No unusual construction methods were employed and no difficul- ties were encountered. Spillway Excavation for the spillway was made initially with a crawler crane equipped with a 5-cubic-yard dragline bucket and later with a small scraper. As excavation progressed, it became apparent that the original loca- tion of the foundation for the concrete-slab crest struc- ture would be unsatisfactory. The crest structure was relocated 100 feet upstream where sound rock had been encountered. Approximately 100 cubic yards of concrete was placed in the spillway chute and weir (Figure 299). Clearing and Crubbing Clearing and grubbing consisted of the removal of all trees, concrete, and other debris in the contract area, as well as the removal of all vegetation over 1 foot in height within the lake area. Because of the concern for Russian thistle control, the reservoir area below elevation 1,578 feet had to be kept continually clear of all vegetation over 1 foot in height during the entire construction period. Tumbleweed control in the entire project area was necessary to adhere to provisions of the California Agricultural Code. Tumbleweeds were cut and wind- rowed. Spring tooth harrows then were pulled through the windrows. Burning the tumbleweeds before harrowing yielded excellent results. In addition to the work required within the reser- voir area, a house, garage, and passive radio-repeater station within the project area were removed. All trees, broken concrete, rubble, and other debris with- in the reservoir area were buried in a pit located 3,200 feet upstream from the Dam. The major portion of the initial clearing and grubbing was completed in No- vember 1970. o eCNCRAL TEHACHAPI AFTERBAY (location v: oso 5/ COTTONWOOD POWERPLANT PUMPING PLANTOUAIL CANAL , OUAIL ±AKE. GORMAN PEACE VALLEY PIPELINE- PYRAMID POWERPLANT :o ELIZABETH LAKE CANYON CREEK- CASTA IC CREEK PYRAMID LAKE KcASTAIC POWERPLANT PYRAMID^ DAM I LAKE HUGHES ROAD ; CASTAX LAKE ANGELES TUNNEL \ELDERBERRY- FORE BAY m CASTAICI SOUTHERN PACIFIC R.R Figure 300. 364 Location Mop — Pyramid Dam and LaiMJm aim? 2r Imp?u >20 01 mou< 404:7 zn)o 5W 01 moo< 059.3QO 0501?me ocx4344.am 16 380 .ouS-uuhhum933 \En Finch xmoiostream of the valve chamber, in the chamber, and downstream of the chamber. Concrete was produced at the Angeles Tunnel south adit batch plant and hauled to the job site by transit mix trucks, which backed into the tunnel to discharge into hoppers. Concrete was pumped from the hoppers through a 6-inch- diameter slickline onto a conveyor belt and then to the placement where it was vibrated into place. The 119-foot-high, reinforced-concrete, intake structure and the reinforced-concrete outlet structure were founded on bedrock. A total of 3,990 cubic yards — Pyramid Dam Major Contracts Comple- Final contract Total costchange Starting tion cost orders date date Pyramid Dam Adits 67-30 Pyramid Dam Initial Facilities.. 69-21 2,498,484 2,558,028 Pyramid Dam and Lake 71-03 22,036,875 26,533,214 71-10 4,552,630 5 71-27 4,222,222 Stations. 73-43 Pyramid Dam... 74-40 3239,250 was removed by a front-end loader which backed out of the tunnel and deposited the muck in a temporary disposal area just outside the portal. Front-end loaders removed muck from the temporary location and hauled it to the designated spoil location just east of the portal. The tunnel was excavated full section to a nominal 17-foot diameter, except the valve transition ?259,018 Prime contractor Anderson Co. and derson Co., Inc. An- 10/18/67 3/25/68 Bill -48,838 10/13/69 2/ 8/71 Shea-Kaiser-Lockheed-Healy 760,662 5/26/71 2/ 1/74 Shea-Healy 4,902,094 347,981 7/ 6/71 4/18/74 Wismer & Becker Contracting 4,479,582 870,189 1/19/72 7/10/73 Kasler Corp., Gordon H. Ball, Inc., & Robert E. Fulton Co. 47,216 57,797 1,522 11/14/73 6/ 7/74 418,796 460,000 9/ 6/74 1/ 6/75 Bill Completion of Angeles Tunnel Intake Works and Pyramid Dam Outlet Works Engineers Ballast Fills for Interstate Pyramid Lake Gauging Completion of (Est.) 392 (Est.) Ray N. Bertelson Co., Inc. Ray N. Bertelson Co. and of concrete Forms was required for these facilities. for these structures were built in place or as close as possible to the site in order to minimize han- dling and transporting. Concrete was placed by using a mobile crane and a 2-cubic-yard bucket. Diversion and Care of Stream In June 1971, Piru Creek was diverted into Pryamid diversion tunnel through the low-level intake controlled at that time by one 30-inch slide gate at the base of the diversion tunnel intake tower. The diversion was accomplished by construction of a 6-foothigh dike across the stream channel. Dewatering of the dam foundation was accomplished by the use of several small pumps situated in low areas. During the fall of 1971, the interim dam was constructed to elevation 2,320 feet, and an interim spillway with a crest elevation of 2,293 feet was cut through the right abutment ridge. The interim dam permitted diversion of project flows through Angeles Tunnel and natural Dam streamflow though two low-level, 30-inch, slide gates in the diversion tunnel intake tower. All natural inflows during the 1971-72 runoff season were passed through the slide gates except those resulting from a Christmas-week storm. During this storm, a flow of approximately 300 cfs flowed over the crest of the interim spillway. Foundation Preparation Overburden. Overburden in the foundation area, comprised of streambed material, old highway fill, and weathered shale, was excavated with rubber-tired front-end loaders with 7-cubic-yard buckets assisted by bulldozers. The material was hauled by dump trucks and rock wagons. Overburden was disposed of in the mandatory waste area at the upstream toe of the Dam, in the buttress fill, and the upstream waste area. Removal of the highway fill in the downstream area of the foundation revealed four old highway bridge bents of reinforced concrete (Figure 323). These were located in the pervious shell section of the Dam, and they were left in place as they did not hinder placement or compaction of the embankment. Shaping. The right abutment of Pyramid Dam was very steep and irregular. Extensive shaping excavation was performed to provide a uniform surface for placement of impervious embankment and to flatten Highway 99 cut slope (Figure 324). Drilling for this excavation started at the end of the Dam in January 1971, and excavation to the slope in the area of the old the stream channel was completed in March 1971. The were presplit with an average inches. This produced a neat line slopes of the excavation hole spacing of 30 excavation with deviations limited, in general, to within 12 inches of the drilled line (Figure 325). Lifts normally were 30 feet deep. Five areas on the dam abutments had overhangs. These were designated as shaping areas in the plans and were required to be laid back to a slope of 1/4:1 in shell areas and 1/2:1 in the core zone. It was required that these areas be removed by the presplit method. Presplit hole spacing was varied from 18 inches to .^6 inches, and it was found that a spacing of 30 inches gave excellent results. Cleanup. After overburden material was removed, the final cleanup prior to placement of embankment was accomplished. In the rock shell zones, this consisted of machine removal of loose material. Backhoes and graders were used for this operation. In the core zone, great care was taken to remove all loose and weathered material to expose fresh solid rock. Final cleanup was by air and water jets (Figure 326). Several deep holes in the stream channel in the core zone backfilled with concrete to provide a uniform encountered were surface which facilitated placement and compaction of the impervious material. Grouting. The Pyramid Dam grout curtain conof a singe line of holes with 10-foot maximum spacing. Grouting was accomplished in three zones by the split-spacing stage-grouting method, usually with to 25 a primary 40-foot spacing. Zone depths were Figure 326. Air-Water Jet Cleanup of Foundatloi sists 50 feet, and 50 to 100 feet. The third zone was extended to 200 feet in three holes in the channel. The holes were drilled normal to the slope. In the feet, 25 to three zones, the pressures at the grout nipple (surface) were 15 psi, 35 psi, and 75 psi. The foundation was tight, and the average grout take was only 0.13 of a bag per foot of hole. Channel Excavation Alluvium in Piru Creek downstream from the Dam was excavated to form the downstream spillway channel. Excavation and disposal of this material was performed in a manner identical to that used for overburden excavation. Embankment Materials The borrow area for the impervious material was located in the lake area about 1 mile upstream from the Dam. It was divided into two subareas: one lying along the east side of the stream channel contained slopewash material and the second was higher on the slopes immediately east of the first and Impervious. was comprised of weathered in-place shales. While both materials were very clayey, slopewash material was somewhat finer than the weathered shale. It was used in the upstream portion of the core, while weathered shale went into the downstream portion of the core. Clearing and grubbing of the impervious borrow which had a brush and grass cover, were done with bulldozers and a small labor crew. The original intent was to strip up to 18 inches of surface material prior to borrowing but, because of the light vegetative cover, this was not necessary and stripping depth averaged less than 6 inches. area, Following clearing and stripping, the area was sprinkled by a portable water system to bring the 394 material to the desired moisture content. Ripping was used to enhance the water penetration, and loading operations were shifted to ensure that properly conditioned materials were delivered to the Dam. In gen- system worked very well, and only minor supplemental sprinkling was done at the Dam site. It eral, this was somewhat more difficult to moisture-condition the weathered shale than the slopewash material. This was because the weathered shale was situated on steeper slopes and water did not penetrate the shale fragments as easily as it did the more uniform slope- wash. Bulldozers pushed the impervious material to frontend loaders which, in turn, loaded the hauling units. Two types of haul units were used: dump trucks (Figure 327), which could haul approximately 20 cubic yards bank measure, and tractors with rear-dump wagons that had a capacity of approximately 15 cubic yards (Figure 328) The haul route was downslope on old Highway 99 to the upstream toe of the Dam and then up a 15% grade on a 40-foot-wide haul road tra. versing the face of the Dam. upstream and downstream shells of the Dam is a hard shale (argillite) obtained primarily from the spillway excavation. Other sources were: the abutment shaping areas, overburden removal, channel excavation, material that had been stockpiled under the initial facilities contract which included the access roads and the Angeles Tunnel gate-shaft bench excavation, and an auxiliary borrow area above the left abutment. Drilling for excavation of the spillway began in July 1971. Initial drilling was accomplished with crawlermounted, air-powered, self-propelled, percussion drills. The air supply was a compressor plant at the Rock Shell. Rock for the toe of the Dam. An 8-inch air-supply pipeline extended from the compressor plant up the west limit of the excavation to the top of the spillway downstream 1 Hauling After adequate access and working areas had been developed, truck-mounted, diesel-powered, rotary drills were used for drilling production holes. A typical drill pattern used with these units was 6y4-inch cut. holes on thickness a 22-foot was 50 ammonium by 22-foot feet. nitrate and The grid. holes fuel oil The maximum lift were loaded with (ANFO) with dyna- mite primers. Detonation was by electric blasting was delivered by bulk trucks and caps. The loaded into the holes with the fuel oil being added as the ammonium nitrate was fed into the hole. The largest blast of the operation comprised 67,225 pounds of explosive. The average powder factor for the spillway excavation was 0.6 of a pound of powder per cubic yard of rock. The cut slopes of the spillway were presplit. Although this was not required by the specifications, the contractor considered this to be economical as it saved barring down and cleanup of the slopes that would have been required with conventional blasting. The specifications were written to preclude the bulldozing of rock so that breakdown during handling would be minimized. Therefore, it was necessary for the contractor to build haul roads from the excavation site, i.e., the spillway ridge, to the dam embankment. This involved roads traversing a maximum difference in elevation of approximately 800 feet and required the use of a 15% haul-road gradient. Two roads were constructed: one to the downstream part of the unlined spillway, and the other from the upstream side of the Dam to the top of the spillway excavation. The downstream road involved a fill of almost 900,000 cubic yards with material from stripping approximately 25 feet of weathered rock from the spillway chute area. As the chute excavation was brought down, this road material was removed and placed in the Dam, if suitable, or otherwise in the waste area. The upstream haul road was cut into the steeply dipping slope of the right abutment until, at a point about 150 feet below the ANFO Figure 328. dam crest, Rear-Dump Rock Wagon Used it swung out onto for Embankment Hauling the upstream buttress fill. The haul units used for transporting rock from the spillway excavation were the same types as used for the impervious material. They were loaded by rubbertired front-end loaders, some of which had a special steel tread to protect the tires in the rocky material. A spread of one loader and five haul units could excavate and haul about 5,000 cubic yards in a 10-hour shift. Maximum daily production for two 10-hour shifts was approximately 30,000 cubic yards. Transition and Drain. Materials for the filter and drain zones of the Dam were obtained from the stream channel of Piru Creek upstream from the Dam. The sands and gravels were dozed into piles and then loaded into the dump trucks and rear-dump wagons by rubber-tired front-end loaders. They were hauled to a stockpile in the lake area about I'/z miles upstream from the Dam site. From the stockpile, they were pushed by bulldozer to a processing plant which separated them into desired fractions. The specifications provided for production of three types of material from the stream-channel borrow ar^a. These were: (1) minus %-inch material for the filter zone. Zone 2A; (2) '/-inch to 6-inch material for the drain zone. Zone 2B; and (3) plus 6-inch rock for riprap. After placement of the first drain zone material, it was noted that undesirable segregation occurred at the interface between drain and transition zones due to the tendency for the larger rocks in the drain to roll to the outside when a lift was placed. Because of concern that this segregation would permit migration of fines from the filter zone into the drain, a change order was issued to provide for an additional transition zone. This added zone comprised a mixture of the drain and filter zone materials and was designat- ed Zone 2D. 395 The processing plant consisted of a grizzly for re- moval of plus 6-inch rock and two sets of vibrating screen decks for separation of the minus 6-inch material into the two desired fractions. The added transition zone, which was essentially a pit-run material with plus 6-inch rock removed, was produced by blanking off the lower screens of the vibrating decks. Production rates varied from 230 cubic yards per hour when producing Zones 2A and 2B to 300 cubic yards per hour for Zone 2D. After production was started, it was found that the dry screening contemplated by the specifications did not remove enough fines to produce filter material with the specified 10% maximum of material passing the No. 200 mesh screen. Wet screening was considered but, after study and additional permeability testing, it was concluded that the allowable amount of material passing the No. 200 screen could be increased to 1 5% without detriment to the Dam. A change order was issued to cover this modification. proportion of %-inch by 6-inch drain zone rock in the borrow pit turned out to be less than contemplated, so a shortage of this material developed. This problem was alleviated by lowering the top elevation of the downstream drain blanket and replacing the upstream drain zone with a zone of weathered rock obtained from dam overburden and spillway excavation. It was still necessary, however, to produce about 100,000 cubic yards of minus %-inch material in excess of what was needed in order to generate the necessary quantity of drain rock. The riprap, drain rock, and transition materials The were hauled to the Dam site by the same equipment and over the same haul route that was used for the impervious fill. Figure 329. Spreading and Compacting of Contact Material on Foundation Embankment Construction Pyramid Dam embankment was constructed in two stages. A low interim dam at the upstream toe of the main dam was built in the fall of 197 to divert project 1 flows through Angeles Tunnel. Construction of the interim dam also provided an excellent opportunity to check out the specified placing and compaction procedures before construction of the main dam. It was found that the specified methods worked well, and no problems were experienced in obtaining desired compaction of the fill when these methods were properly followed. Placement of impervious fill in the in August 1971. The first step was to cover the foundation area with contact material which was placed about 2% above optimum moisture and wheel-rolled with a rubber-tired frontend loader with a loaded bucket (Figure 329). Throughout placement of the core sections, the contact material was placed about 2% wetter than the remainder of the impervious fill so that it would easily conform to irregularities in the rock surface. As the Impervious. interim fill dam commenced progressed, a layer of contact material 10 to 15 feet wide was brought up ahead of, and compacted prior to, the rest of the embankment. The abutment contact line generally was maintained 1 to 2 feet higher than the plane of the embankment, with the surface sloping gently away from the abutment. These measures were taken to ensure coverage of the foundation with the wetter material and to preclude the possibility of loose material rolling into a low area against the abutment and being poorly compacted. After compaction of contact material to an approved elevation, the impervious embankment was Figure 330. Rolling of Impervious Fill 396 1 raised to that elevation. After being dumped by the hauling units, the material was spread with a bulldozer into 8-inch loose lifts, then processed by at least two passes of a disc. At this time, if any supplemental moisture was required, it was added by a water wagon. After disking, the lift was compacted by 12 passes of a self-propelled, four-drum, sheepsfoot roller (Figure 330). Compaction of the fill was closely monitored with an average of one relative compaction test being taken for each 2,500 cubic yards of fill placed. The average relative compaction for the impervious embankment was 98.5%. was dumped and spread and then rolled with two passes of a vibrating drum roller (Figure 331). Both selfpropelled and towed rollers were used. The compacting and grading of this material were closely monitored by testing. These tests involved considerable Shell. Rock shell material in 3-foot-thick layers effort as a field density test required the excavation and weighing of 1,000 to 1,500 pounds of rock, and mechanical analyses required the screening of several thousand pounds of material. Transition and Drain. Material for the transition and drain zones was spread in 18-inch lifts. Transition material was compacted by two passes of a vibrating roller and drain material by one pass. Here again, compacting and grading were closely monitored by daily field testing. Spillway After the spillway area was e.xcavated down to the elevation of the unlined chute, the cut for the 40-footwide concrete-lined chute was made using presplitting to shape the cut slopes against which concrete lining was placed. ^::^W :r^P • ^:^-' Forms. The basic form used for the wall placements was a 32-foot-long, prefabricated, steel form complete with struts which spanned the spillway width and formed both side walls at one setup (Figure 332). Form heights were adjusted by addition or removal of panels. A system of jacks and ratchets enabled adjustment of the form for sloping walls. This unit was pulled up the slope by a double-drum hoist which was anchored at the top of the 85% slope. The form assembly was supplemented by wooden panels where necessary, and transverse joints in the walls were formed with wood. The invert slab of the spillway was formed with a 10-foot-long by 40'X-foot-wide, steel, slip form with a weight of approximately 60 tons. This was comprised of six 27-inch WF beams spanning the chute slab. These beams were tied together by four 6-inch WF beams at the top and a '/-inch-thick skinplate on the bottom. The spaces between the beams were filled with concrete. The form was suspended by steel wheels riding on 75-pound rails which were supported by a system of 3-inch pipe posts and No. 1 1 reinforcing steel braces grouted into the rock in the wall sections of the spillway. The rails were set V/i feet above spillway invert grade. The slip form was pushed forward (upslope) during concrete placement by two 6-inch hydraulic rams which were clamped to the rails. The cylinder stroke was 6.5 feet so several strokes were required to complete a 30-foot slab. While the cylinders were being retracted and reclamped, the slip form was anchored by cable to the double-drum hoist at the top of the slope. The headworks structure walls were formed with a combination of steel and wood forms and were placed in 14'/2-foot lifts. Concrete Placement. The concrete was hauled to the placement site in transit mix trucks. Two five-man labor crews, one for concrete placement and one for cleanup, worked a normal day shift; an additional labor crew worked a night shift to sandblast, clean up, and prepare for placements. Consolidation of the concrete primarily was done with 6-inch immersion-type vibrators. In some instances, 3J4-inch vibrators were used to supplement the larger ones and to consolidate in congested areas. The portion of the lined spillway to be placed slab of the upper chute, which was on a 2% slope. Concrete for the ten 30-foot-long sections was placed by crane and bucket, with the crane being situated on the invert of the unlined spillway. The concrete was struck off by a rail-mounted screed, 3 feet long and 40'/ feet wide. This screed was a segment of the slip form to be used on the steeper slopes and was moved by hydraulic cylinders clamped to the rails. A platform from which the finishers worked was pulled behind the screed. A steel trowel finish was specified for the invert, and cold weather, which prevailed at that time, retarded the concrete set and first was the invert 398 caused long finishing hours. In general, these placements proceeded well and the contractor was able to make one 30-foot section per day. The headworks structure was the second spillway feature to be placed. The major problem encountered in this work was in connection with placement of the invert slab. An attempt was made to place the entire invert in one placement (2,000 cubic yards) by utilizing "drop pipes" in conjunction with one crane and 4-cubic-yard-capacity buckets. The drop pipes consisted of five 10-inch-diameter steel pipes along each side of the headworks (Figure 333). Concrete was dumped directly from buckets into the center of the invert and dropped through the pipes along the sides. Small hoppers about 2 feet square were mounted on top of the pipes. Concrete was conveyed from the transit mix trucks to the hoppers by chutes. Discharge of the concrete from the trucks through the gently sloping chutes was very slow. The large aggregate tended to roll down the chutes, jump over the hoppers, and fall among the workmen below. Concrete also plugged the pipes several times; it tended to stack at the pipe outlets and had to be flattened and moved with vibrators. Surprisingly, little segregation was noted at the pipe outlets. After ten hours of placing, and with only about one-third of the invert done, the contractor elected to stop the placement and make a construction joint. Prior to placing the second lift of the invert, the inlets of the drop pipes were lowered, chutes steepened, and an additional crane brought in. These changes increased the placement rate significantly, and the remainder of the invert was completed without any major problems. After completion of the headworks concrete, the chute walls in the 2% slope section were placed. Both walls were placed simultaneously and were formed by a steel-form strut assembly. Except for tight clearances due to the narrow wall, no major problems were encountered and the contractor was able to place a section every other day. After completion of the walls on the 2% slope, the 85% slope section was placed. The slip form performed well and produced a good surface that required little additional hand finishing. Movement of the slip form was slowed by trouble in attaching the ram clamps to the rail. Attaching and releasing these clamps was a major factor in delaying many of the placements. The concrete was spotted in front of the slip form by a 120-ton crane with up to 220 feet of invert of the boom. This crane was able to reach the lower 3 sections from the toe of the unlined spillway slope, the next 1 1 sections from the right adit bench, and the remaining section from the top of the 85% slope. When operating with the maximum length of boom, placements were slow due to the flexibility and resultant "bounce" of the boom. Also, in several areas, the operator was operating "blind" and had to spot the bucket by telephone, radio, or hand signals. Despite these conditions, one invert section per day was placed (Figure 334). In placing the wall sections on the steep chute, the same problems with operation of the crane were encountered as for the invert. Also, due to the steep slope, the tops of the walls had to be formed as placement progressed. The final feature of the spillway to be placed was the flip structure at the end. It was placed in four lifts, and no major problems were encountered except for some difficulty in slip forming the invert, which was on a 40-foot radius. A 3-foot-long slip form on curved pipe rails was used for this. In general, the concrete for the lined spillway turned out well despite the narrow battered walls and steep slope. Considerable repair work was required along the tops of the walls. The concrete was well consolidated and reasonably well finished. Figure 332. Radial Gate The ricated 31-foot-high, 40-foot-wide, radial gate by Hopper, was Prefabricated Sfeel Form Used for Spillway Walls fab- Inc. in Bakersfield, California. Pri- or to shipment, the entire gate was fabricated with two 8-inch pipe spreaders, assembled in the shop, and checked for correct spacing and alignments. Temporary installation of the same two spreaders in the field facilitated correct positioning of the trunnion girders. On October 30, 1975, the gate was lowered to contact the sill plate and was found to have a %-inch bow in the bottom edge. Under the direction of the manufacturer, the gate was straightened by the alternate application of controlled heating and cooling to within a tolerance of plus or minus '/ inch. Final adjustment of the gate sill plate was made by lowering the gate and adjusting the plate to meet the bottom edge. The gate installation was quite good as attested by the fact that, when the reservoir was filled, leakage past the side seals was nil and only a couple of damp spots showed up downstream of the bottom seal. Access and Air-Supply Tunnel Figure 333. Concrete Placemen Heodworks Invert 'rttn^ Driving of the access tunnel was started on July 1, and completed on July 23, 1971. The contractor worked 27 ten-hour shifts in driving the tunnel an 1971 average of 28 feet per shift. The air-supply tunnel is a circular tunnel 5 feet in diameter and 90 feet in length connecting the crown of the access tunnel with the crown of the valve chamber of the Pyramid Dam diversion tunnel. This tunnel was completed in six 10-hour shifts with an average advance of IS feet per shift. The equipment used by the contractor was left over from the Angeles Tunnel job. The jumbo was contractor-built and modified to adapt it to the access tunnel size and shape. The 8-foot by 1 1-foot access tunnel was driven about 1 foot oversize at the contractor's request as he elected not to reduce the basic size of the jumbo. The contractor was not paid for the extra concrete lining in the overexcavation. The jumbo was on rub- Figure 334. Concrete Placement rn Spillway Chute Slob 399 ber tires, pneumatic mounted with four upper and two lower. These 1/2 inches in diameter, and a 3-inch each round. Compressed air for the was supplied by three 600-cubic-feet- diesel-powered, and drills drilled 45 holes, "burn" hole for drilling initially — two per-minute (cfm), portable, air compressors. Later, portable, air compressors were used. At the end of tunnel driving, compressed air was supplied by two 2,000-cfm and two 1,200-cfm stationary air compressors. These last compressors also supplied air to other drilling operations on this contract and to the Angeles Tunnel intake works contract. After drilling of a round was completed, the holes two 900-cfm, were loaded (using the jumbo as the loading plat- form) with caps being used to control the sequence of the blast. After a shot was set off, the tunnel was ventilated using a 7'/2-horsepower ventilating fan with a 35,000- cfm capacity. The muck pile was removed from the face and hauled out of the tunnel by a front-end loader. After the muck pile was completely hauled out, the jumbo returned to the face to resume drilling. There were no problems or delays during tunnel driving. No water was encountered. The tunnel was monitored for explosive and hazardous gases, but there was never any indication of their presence. No steel supports were used in the tunnel. After the driving operation was completed, the contractor elected to place shotcrete, approximately '/2-inch thick, in two areas intersected by beds of Pyramid shale which were much softer and more fractured than the Pyra- mid argillite. Preparations for lining the access tunnel and the air-supply tunnel were begun on June 26, 1972. Work included scaling loose material from the walls and the invert. The first concrete placement of the tunnel lining was made on July 11, 1972, and the concreting was completed with the placing of the portal structure on October 26, crown and removing loose muck from 1972. Six concrete placements were made for the tunnel placements were required for the walls and crown, two for the air-supply tunnel, and one for the portal structure. All concrete for the tunnels was produced at the invert. Sixteen batch plant and transported into the tunnel in transit mix trucks. Concrete for the invert section was a standard design five-sack mix with I'/jinch maximum size aggregate. Wall and crown section concrete was the same mix except that sand content was increased to approximately 40% to facilitate job-site, central, pumping. The initial invert placement was made using manu- operated buggies. Due to the excessive amount of labor required for this method of placement, the remainder of the invert was placed using a belt conveyor. Use of the over 200-foot-long, self-propelled, conveyor belt enabled invert placements to proceed ally 400 with a minimum of labor and with no major problems. 6-inch and 3-inch, The concrete was consolidated with pneumatic, immersion vibrators. Inconsistent slump of the concrete and lack of competent finishers were the primary problems encountered in the invert placements. Scheduling of reinforcing steel installation to prevent congestion in the tunnel was another persistent problem. A 6-inch hydraulically operated pump was used for the first placement of the walls and crown. Plugging of the 8-inch slickline occurred several times during this placement, so this pump was replaced with an 8-inch mechanically operated pump for the remainder of the wall and crown sections. This pump performed satisfactorily and could handle the desired 4 inches or less slump concrete. Up to 450 feet of slickline was used. Air sluggers were used along the slickline to aid in moving the concrete. A 45-foot-long steel form was used for the normal section of the walls and crown. This form was mounted on dolly-type wheels and was hinged at the crown. A system of ratchets and jacks folded and lowered the form, which enabled easy and fairly rapid spotting and removal of the forms for each placement. The form was towed along the previously placed invert sections by an air tugger mounted on the form. Although the form had access and inspection windows, the large amount of overbreak in the tunnel enabled access inside the forms for concrete placement and consolidation. Consolidation of the wall and crown areas was done with 6-inch and 3-inch, pneumatic, immersion vibrators as well as external form vibrators. Adits The adits in the abutments were excavated under an paving and shotcrete lining earlier contract. Invert were added under the dam contract. Concrete in the left adit invert was placed by laborers pushing buggies from the portal. This was so difficult that the contractor changed the method for the right abutment. Concrete in the right abutment was placed by a 6-inch pump through a 4-inch slickline. It had '/-inch maximum size aggregate. The left adit required 167 cubic yards and the right adit 290 cubic yards of concrete. After placement of the inverts, shotcrete was applied to the walls and crown. A dry mix was used with water being added at the nozzle. The pot was positioned at the portal and was fed by transit mix trucks. As much as 900 feet of hose was required to reach the ends of the adits. Completion of Outlet Works Intake Structure Contract work for the completion of the outlet works intake structure was started on July 26, 1972. In order to place concrete in the intake tower plug, maintain the required water level upstream of the interim dam, and provide water release facilities during the winter of 1972-73, it was necessary to install 30- inch pipe extensions on the two low-level, 30-inch, and a 10-inch pipe extension on the low- slide gates level, 10-inch, butterfly valve. One interim slide gate was not provided with sealing surfaces and a 1-inch bolt had been left under the gate during a previous contract. As the gate was under approximately 30 feet of head, partial sealing was accomplished from the outside with gravel and cottonseed hulls. The remaining leakage was collected in a 6-inch pipe, which was grouted full after completion of the plug. During the period when the contractor was placing concrete for the intake plug, he completed the installation of the vertical trashracks, checked and prepared the horizontal trashrack for proper fit, and installed the seals for an 18-foot-diameter dished head. The other 30-inch slide gates remained in operation until May 8, 1973 and then were grouted full. The 10-inch pipe was extended through the diversion tunnel with a 12-inch pipe to allow the contractor to complete valve chamber work while maintaining a minimum flow of 10 cfs in Piru Creek. The 18-footdiameter dished head was installed on the intake tower on May 8, 1973 to permit the reservoir level to rise above the intake tower. During the summer and fall of 1973, the 10-inch butterfly valve was operated to maintain minimum flows in Piru Creek. On December 11, 1973, the 10inch butterfly valve was found inoperative and could not be closed. An attempt was made to seal the valve from the outside with a steel cap fitted with a rubber sealing surface. This was done by divers at a depth of 223 feet. Due to poor visibility and extreme depth, the sealing was unsuccessful. It was essential that the pipe be sealed and the dished head removed from the tower to provide discharge capabilities through the outlet works. On January 7, 1974, equipment and materials were moved in for grouting the 10-inch pipe. The next day, the grouting pipe was installed and the 10-inch pipe grouted with an expansive cement-pozzolan slurry. January 9, 1974, the inside 10-inch valve was opened and the pipe was found to have only minor leakage. The valve was removed, a blind flange installed, and the concrete blockout and cleanup completed on January 11, 1974. On January 17, 1974, the equalizer plug on the 18foot-diameter dished head was pulled and the dished head removed from the intake tower. On January 18, 1974, the horizontal trashrack was lowered onto the intake tower. During lowering of the trashrack, the cable sling became entangled under the trashrack, preventing seating. Divers completed the seating of the trashrack on January 19, 1974. On concrete. This machine was equipped with a rotating arm, a scabbier unit on each end of the arm, and seven vibrating scabbier heads in each unit. The machine was self-centering on supporting wheels and was airand hydraulically operated. Considerable adjustment and changes were required before the scabbier became fully operational. The machine did an extremely effecproviding a rough irregular surface for the plug concrete. Areas in the valve chamber and plug that could not be reached with the scabbier were bushhammered by hand. On completion of the concrete chipping, the piping and reinforcing steel were intive job of stalled in the plug. The concrete was placed in the tunnel plug on The diversion tunnel was too small for concrete trucks so permission was given to pump concrete from the diversion tunnel entrance to the plug first August 7, 1973. and valve chamber area. The maximum pumping distance was 830 feet with a vertical lift of 39 feet. The pumping was done by a concrete pump through a 6-inch slickline. The mix used had I'/j-inch maximum size aggregate and contained 400 pounds of cement and 70 pounds of pozzolan. This mix was pumped satisfactorily with a slump of 4 to 5 inches at the pump. The slump loss in the slickline was 1 inch. Vibration of the concrete was effectively handled with 6-inch vibrators. Concrete was obtained from a plant located near the work site until November 15, 1973. After that, concrete was obtained from a supplier at Castaic. Concrete was mixed and transported to the job site by transit mix trucks. Total concrete placement in the tunnel plug and valve chamber was 898 cubic yards. Mechanical and Electrical Installations The contractor moved the westerly 42-inch plug valve into the valve chamber on October 27, 1973. Transporting of the valve through the diversion tunwas accomplished with a four-wheeled cart with wheels sloped to conform to the curvature of the tunnel. The cart was pulled into the chamber by an electric winch. Rock bolts with lifting eyes were installed at the center of the tunnel just ahead of the valve deck, and four 10-ton chain hoists were used to lift the valve above the deck elevation. Steel I-beams were installed under the valve, four sets of wheels were placed under the valve, and the valve was transported along the beams to the deck. The valves then were jacked into position over the anchor plates and lowered. All valves were transported in a similar manner. Installation of the 78-inch valve was delayed because the contractor's proposed anchorage was not satisfactory, and considerable revision for the valve and operator was required to prevent uplift during nel The 78-inch valve was moved into the November 10, 1973, and final positioning was completed on December 5, 1973. The piping for the tunnel plug and valve chamber valve stroking. Diversion Tunnel Plug tunnel on On June 6, 1973, the contractor installed a concrete chipping machine (scabbier) in the diversion tunnel plug area to remove the required 1 inch of surface was fabricated and hydrotested to 275 psi in position 401 or outside the tunnel, depending on the pipe size, length, and installation problems. This was accomplished in two phases: the upstream inlet sections ahead of the valves and the downstream discharge sections. This procedure tested all the field welds except the nipple weld to the pipe flanges at the valves. The Department accepted radiographing of these welds in hydrotest. All welds were ultrasonically tested prior to hydrotesting or radiographing. All welding was satisfactory except about 6 lieu of the specified inches of longitudinal factory weld just upstream of the 78-inch valve which was satisfactorily repaired. Installation of the fixed-cone dispersion valves start- ed as soon as the downstream sections of pipe were installed and aligned. Piezometer piping was installed as main piping was completed. In the Pyramid Dam outlet works, epoxy coating was applied to all metalwork and valves in the dispersion chamber, to the interior of all piping 4 inches and larger, to the sump pumps and appurtenances, and to all exterior ferrous and galvanized surfaces exposed to water. Exposed ferrous metalwork and galvanized piping within the valve chamber which was not exposed to water was primed with a red-lead alkyd and finished with machinery enamel. Coatings generally were not applied until all major work items had been completed. This procedure provided a better-appearing finished product and eliminated considerable touchup work although it did require additional surface preparation where metal- work had become rusted. Miscellaneous mechanical work included the air ventilation fan and duct systems, and sump pumps in the valve chamber. With the exception of the sump pumps, the work was performed without difficulty. The sump pumps are operated by water-level pressure switches and were found to be extremely difficult to adjust and maintain. The pump transfer relay did not function correctly and was replaced. Electrical installation for the Pyramid outlet works included the embedded conduit in the valve chamber, surface runs in the valve chamber and diversion tunnel, electrical-duct shaft, completion of the conduit runs to the spillway motor control center, control cabinets, and all devices required to complete the electrical installation. Electrical 402 work was completed as equipment was installed and made ready for opera- tion. Instrumentation All 21 piezometers functioned properly for a period by July 1973, all those above after installation but, elevation 2,300 feet had failed. The plastic tubing to all of these tips contained vertical runs, and it is surmised that the riser tubing failed in the vicinity of elevation 2,260 feet due to high consolidation of the impervious material in this area. The slope-indicator data showed that embankment settlement in this area was approximately 6 feet. Open-tube piezometers were installed in holes drilled from the crest of the Dam to the inoperative piezometers. The drilling fluid in these holes evidently caused temporary hydraulic fracturing of the core, and some of the drilling fluid was lost. The fracturing was determined to be possible because the effective overburden pressure in the core had been reduced by the stiffer transition and shell zones carrying the weight of the core. Extensive exploration and supplemental analyses showed that there was no permanent affect on the Dam. Performance of the Dam since then has verified this conclusion. A finite element stress analysis is being conducted to check the details of the estimated stress conditions. The slope-indicator installations were comprised of .S-foot sections of extruded aluminum tubing approximately 3 inches in diameter. The tubing has four tracking grooves which guide the slope-indicating device. It was found that the grooves in the tubing had a slight twist which caused a rotation in the grooves as the individual sections of tubing were added. When this was discovered, slope indicator No. 3 had rotated over 8 degrees. At this time, measures were taken to correct this and eliminate future rotation. This was done by using a spanner wrench to twist the added section of tubing in the desired direction while it was riveted to the previously installed section. This proved successful and, thereafter, installations were held within the prescribed tolerance of plus or minus 3 degrees of the specified orientation. Another problem was that the settlement of the embankment tended to move slope indicators Nos. 2 and 4 away from the dam abutment. This required correction as each section was added. A great deal of survey crew time was required to monitor the orientation and location of the slope indicators. I BIBLIOGRAPHY Marachi, N. D., Chan, C.K., and Seed, H. B., "Evaluation of Rockfill Materials", Mechanics and Foundation Division, January 1972. ASCE Journal of the Soil Stroppini, E. W., Babbitt, D. H., and Struckmeyer, H. E., "Foundation Treatment for Embankment Rock", ASCE Journal of the Soil Mechanics and Foundation Division, October 1972. Dams on 403 GENERAL LOCATION TEHACHAPI AFTERBAY 030 COTTONWOOD PUMPING PLANT POWERPLANT GORMAN PEACE VALLEY PIPELINE CANYON ROAD POWERPLANT ELIZABETH LAKE CANYON CREEK PYRAMID LAKE I PYRAMID CASTAIC I LAKE HUGHES ROAD ANGELES TUNNEL Vv LAKE EL DERBERRY CASTAIC FOREBAY DAM CASTAICO- LAGOON 2 MILES 3 SOUTHERN FILLMORE 9% Figure 335. location Map?Castoic Dam and lake CHAPTER CASTAIC XV. General Description and Location Castaic tion Dam rises 425 feet above streambed excava- and spans 4,900 feet between abutments crest. The up of a central shells with appropriate transition zones. 46,000, 000-cubic-yard embankment is at its made impervious core flanked by pervious The spillway is located at the right abutment of the and consists of an unlined approach channel; a 360-foot-wide, ungated, ogee weir; and a 5,300-footlong lined chute with energy dissipator. Dam The works provides delivery of water penstock installed inside the 27-foot-diameter, former, diversion tunnel. Downstream control is provided through a valving complex for stream releases up to 6,000 cubic feet per second through outlet a 19-foot-diameter (cfs), delivery to voir emergency water users up to 3,788 releases. cfs, and reserUpstream control is pro- Figure 336. Aeriol View DAM AND LAKE vided by a multiple-level, high, intake tower equipped with 72-inch butterfly valves. Elderberry Forebay located at the upper end of, and separated from the right arm of, Castaic Lake provides regulatory storage for Castaic Powerplant. Downstream of the Dam, Castaic Lagoon, a former borrow area, now serves as a recreation area and a recharge basin. Castaic Dam and Lake are located about 45 miles northwest of Los Angeles and about 2 miles north of the community of Castaic at the confluence of Castaic Creek and Elizabeth Lake Canyon Creek (Figures 335, 336, and 337). Elderberry Forebay Dam (owned and operated by Los Angeles Department of Water and Power, LADWP) is located 3/2 miles upstream of Castaic Dam on Castaic Creek. The weir that contains Castaic Lagoon is located V/i miles downstream of Castaic Dam where Lake Hughes Road crosses Castaic Creek. The nearest major highway is Interstate Highway 5, about 2 miles to the west. —Castaic Dam ond Lake 405 VI A In: CI ensure an PLAN- SAFETY - - Nu?y - LAGOON 4" - n. a a \ccocc '1'6 KC Figure 337. Site Plan Purpose Chronology was built to accomplish the following: (1) provide emergency storage in the event of a shutdown of the California Aqueduct to the north, assuring water deliveries to the West Branch water users; Studies by the Department of Water Resources indicated that storage of any appreciable amount at the terminus of the West Branch Aqueduct would be provided most logically and economically at the Castaic (2) act as regulatory storage for deliveries during normal operation; and (3) provide a setting for recreational development by state and local agencies for the Southern California area. Although flood control is not a primary purpose, inflows of up to 61,000 cfs will be reduced to the capacity of the downstream channel. Elderberry Forebay serves three purposes: (1) provides 18,000 acre-feet of live storage which can be utilized by Castaic Powerplant during off-peak hours for pumpback into Pyramid Lake, (2) provides submergence for the pump-generator when Castaic Lake is at its lower operating levels, and (3) reduces daily and weekly fluctuations in Castaic Lake. Castaic Lagoon originally was a borrow area for the construction of Castaic Dam. Now, its purposes are (1) to provide a recreation pool with a water surface at a constant elevation of 1,134 feet, and (2) to function as a recharge basin for the downstream ground water basin. Dam site. Planned storage capacity of Castaic Lake has varied from 150,000 acre-feet in 1959, to 370,000 acrefeet in 1960, to 100,000 acre-feet in 1961, and to 350,000 acre-feet in 1963. The final decision to increase the capacity of Castaic Lake from 100,000 acre-feet to 350,000 acre-feet was made to utilize the optimum capability of the site in providing terminal storage for regulatory and emergency requirements. With the construction of Elderberry Forebay by LADWP, storage in Castaic Lake was reduced to 323,702 acre-feet. Castaic Lake TABLE 42. Statistical Summary was started in January 1964, excavation August 1965 in a foundation trench, and the completion contract was finished in June 1974. Statistical summaries of Elderberry Forebay Dam and Forebay and of Castaic Dam and Lake are shown in Tables 42 and 43, respectively. The area-capacity curves are shown on Figure 338. Final design was started of Elderberry Forebay in Dam and Forebay ELDERBERRY FOREBAY DAM SPILLWAY Type: Zoned earthfiU Emergency: Ungated ogee draw Crest elevation Crest width Crest length 1,550 feet 25 feet 1,990 feet Streambed elevation at dam Lowest foundation elevation 1,370 feet 1,350 feet axis Structural height above foundation Embankment volume 200 feet 6,000,000 cubic yards Freeboard above spillway crest Freeboard, maximum operating surface 20 feet 10 feet crest with lined channel, discharge into 1,540 feet Crest elevation Crest length 420 feet Service: Glory hole with reinforced-concrete conduit basin 10-foot-high stoplogs provided at crest 1,540 feet Top of stoplogs 1,530 feet Crest elevation 173 feet Crest length, elevation 1,540 feet. elevation feet126 feet 1,530 Crest length, — Crest diameter 54.9 feet Conduit diameter 21 feet and stilling spillways: No stoplogs in service spillway 28,747 cubic feet per second One-in-l,000-year-flood inflow 28,747 cubic feet per second Outflow with 5 feet of freeboard.. Combined ELDERBERRY FOREBAY INLET-OUTLET Maximum operating storage* Normal maximum operating storage Minimum operating storage Dead pool storage Maximum operating surface elevation Normal maximum operating surface elevation Minimum operating surface elevation Dead pool surface elevation Shoreline, spillway crest elevation Surface area, maximum operating elevation __ Surface area, spillway crest elevation Surface area, minimum operating elevation.. * 33,004 acre-feet 28,231 acre-feet 19,041 acre-feet 811 acre-feet 1,540 1,530 1,480 1,412 feet feet feet feet 7 miles 492 acres 460 acres 379 acres Storage above elevation 1,530 feet to be utilized only during the months of May and June when additional storage on the CaliAqueduct may be required. fornia Castaic Powerplant Maximum generating release Pumping capacity tailrace 18,400 cubic feet per second 17,300 cubic feet per second OUTLET WORKS Type: High-level, spillway conduit beneath dam along base of right abutment; low-level, reinforced-concrete conduit with valve chamber adjacent to glory-hole spillway discharge into spillway — conduit downstream of elbow Diameter: High-level, 21 feet — low-level, 7 feet Intake structures: High-level, slide gates on spillway shaft; lowlevel, uncontrolled box with stoplog emergency bulkhead Control: High-level, two 8-foot-wide by 9-foot-high slide gates at elevation 1,498 and six 8-foot-wide by 12-foot-high slide gates at elevation 1,477 on spillway shaft; low-level, single set of two 5foot-wide by 6-foot-high, high-pressure, slide gates in tandem within gate chamber 17,000 cubic feet per second Capacity 407 TABLE 43. CASTAIC Type: Zoned Stalislical Summary Dam and 1 Lake DAM SPILLWAY Type: Ungated ogee earthfill Crest elevation Crest width Crest length of Castaic 1,535 feet 40 feet 4,900 feet ..- crest with lined chute 1,200 feet 1,110 feet axis 425 feet Structural height above foundation Embankment volume 46,000,000 cubic yards surface elevation 120,000 cubic feet per second 78,400 cubic feet per second 1,530 feet One-in-400-year-flood inflow Peak routed outflow Maximum surface elevation 61,000 cubic feet per second 27,200 cubic feet per second 1,522.7 feet probable flood inflow Peak routed outflow Maximum 20 feet 20 feet Freeboard above spillway crest Freeboard, maximum operating surface Freeboard, maximum probable flood stilling basin 360 feet Maximum Streambed elevation at dam Lowest foundation elevation and 1,515 feet Crest elevation Crest length INLET 5 feet Elderberry Forebay outlet 17,000 cubic feet per second Capacity.. OUTLET WORKS CASTAIC LAKE Maximum operating storage Minimum operating storage Dead pool storage _ _ 323,702 acre-feet 18,590 acre-feet 18,590 acre-feet Dead 1,515 feet 1,280 feet 1,280 feet pool su rf ace elevation Shoreline, maximum operating elevation maximum operating elevation. minimum operating elevation.. Surface area, Surface area, _ 29 miles 2,235 acres 372 acres — steel and stream Maximum operating surface elevation Minimum operating surface elevation — upstream of tunnel plug, right abutment downstream, 19-foot-diameter 19-foot-diameter pressure tunnel conduit in a 27-foot-diameter tunnel to delivery manifold Type: Lined tunnel under releases Intake structures: Low-level uncontrolled tower with provision for steel plug emergency bulkhead and 6-foot by 10-foot coaster gate shutofi' at junction with high intake; high-level vertical ninelevel tower with 72-inch butterfly shutoff valves Control: Regulation by water users beyond downstream delivery manifold stream release, series of rated valves in a structure immediately downstream of the deliver)' mainfold 3,788 cubic feet per second Design deliveries 6,000 cubic feet per second Capacity, stream maintenance 11,000 cubic feet per second Capacity, reservoir drainage — RESERVOIR SURFACE AREA (100 Ac.) Regional Geology and Seismicity Castaic Dam site, approximately 10 miles southeast of Pyramid Dam, is approximately 3 miles northeast of the San Gabriel fault and 1 3 miles southwest of the San Andreas fault. The section on regional geology and seismology in Chapter XIV of this volume applies to Castaic Dam as well as Pyramid Dam. Design of Elderberry Forebay Elderberry Forebay was designed and constructed by the City of Los Angeles Department of Water and Power. Operation Castaic Powerplant, located between Pyramid Lake and Elderberry Forebay, generates during peak demand periods when the value of energy is high and pumps water back to the higher level of Pyramid Lake during off-peak periods when the value of energy is low. On a daily basis, approximately 18,000 acre-feet of water is used for power generation during the day, 8,000 acre-feet of which is pumped back at night. This leaves a daily flow of about 10,000 acre-feet through Elderberry Forebay to Castaic Lake. On weekends, a full 18,000 acre-feet of live storage from the Forebay (a 60-foot drawdown) can be pumped to Pyramid Lake using off-peak power. Then, during the week, drawdown can be replenished with part of the daily 18,000-acre-foot flow from Pyramid Lake. Under normal operating conditions, minimum water surface in Castaic Lake may be at about elevation 1,435 feet each year, which is 45 feet below the minimum operating surface of the Forebay. Under these conditions, the Forebay is necessary to supply submergence for the Castiac Powerplant tailrace. this Embankment The 160-foot-high earthfill forebay embankment is a zoned with free-draining material in the upstream The downstream more gradual, is of pervious material protected from the wave wash of Castaic drawdown rapid where drawdown area. section, will be Lake by V/i feet of soil-cement. The depth of Castaic Lake on the toe of the forebay embankment will be at least 55 feet under normal operation. A core trench is provided to sound rock under the impervious Zone 1 material. An emergency spillway discharges across a ridge abutment and into a draw that returns to Castaic Creek near the toe of the Forebay Dam. The east of the left spillway consists of an unlined approach channel with side slopes protected by riprap; a 4-foot-high, ungated, ogee crest; and a concrete-lined chute. Outlet Works level outlet and The gates and above the elbow of the outlet, the diameter of the shaft reduces from 40 to 21 feet. At the toe of the Forebay Dam, the 21-foot pipe discharges into a transition to a flume which empties into a concretelined stilling basin. Backwater from Castaic Lake stands above the top of the elbow at the base of the shaft, except in case of emergency draining of the system. The low-level slide-gate outlet consists of an intake structure with a trashrack; a 10-foot-diameter pressure conduit; a gate chamber containing two 5- by 6-foot, motor-driven, remotely operated, pressure gates; and a 7-foot-diameter outlet pipe that discharges into the 21-foot-diameter, high-level, outlet discharge line. Design of Castaic Dam Diversion Tunnel Dam served to diThe diversion tunnel for Castaic vert floodflows during construction of the embankment and now serves as part of the outlet works. The diversion tunnel passes through the right abutment under the embankment. The finished tunnel lar concrete-lined section, is a circu- 19 feet in diameter from intake to Station 25-1-90 and 27 feet in diameter from that point to the outlet. The total length of the tunnel is 3,766 feet (Figures 339 and 340). reinforced-concrete channel extends from the di- A version tunnel outlet portal to an energy dissipator. The channel and dissipator were utilized to pass floodflows during construction. Later, the channel was modified to meet the needs for turnouts and stream release facilities. The stilling basin was designed for use with the stream release facilities as well as the diversion tunnel. The diversion tunnel contract provided for construction of the diversion facilities plus the necessary provisions for their later incorporation with the delivery and stream release facilities. The upstream portal structure included a foundation pad for a low intake tower and a tower barrel to an elevation above the diversion tunnel soffit. At Station 20-1-18, provisions for a high-level intake. The downstream consisted of a concrete channel with a semicircular to rectangular transition section, a rectangular channel, and a hydraulic-jump energy dissipator (stilling basin) at the downstream end. The downstream structure also included provisions for a delivery penstock and was designed to serve as the were made facilities Emergency Spillway The intake has 12 stop-gate bays around its crest and slide gates at two levels below the crest. Closing of the stop gates on the crest will raise the Forebay 10 feet, to the level of the emergency spillway crest. Below the slide works of the Forebay consists of a high- a low-level outlet. is a 64'/2-foot-diameter gloryhole-type intake with a 40-foot-diameter shaft. The high-level outlet foundation for the delivery branch bifurcations and stream release structure. Hydraulics. The diversion tunnel, as designed and constructed, could have passed the standard project flood, which has a peak inflow of 58,000 cfs, with a maximum reservoir water surface elevation of 1,306 feet and a peak discharge of 14,600 cfs. The diameter 409 410 Figure 339. Diversion Tunnel?Plan and Pro?le an I1 mun? 0 (14' gal cover 0 Ignnl' v' 01:, na' gammy . hr! . 3. I l/ r-nn 199 a (mum, ground llnu I Ira?w? I 79') um new? 00 . ulw 2 boar-.ln'lr/ Ila: 4151.. ""35 :7?05. rum-u 31m." [Irv (:99 .. an nu Ian-n) ?4 um lI-ll mu rune "In 1:01! l?naa? 'u u-u VOTES arm 1/1 tin-mu [nuIlium r-m 5AFETY a by . a mun- nu e! um Mn ear?u- a An ".11 nau- nun-u mum-u mum DIVERSION TUNNEL PLAN no "07le ?lh'r! 44,. m. -. - =5;<33 Ha ;!2?3gzg . ?3 I I Egv?m! I ll:3:051 :it:- i on . A .vw Chan/vol 75mm? 09 01.1: w? angina! 9 man: m! 4 4040a 8 3 9 "u A?/l mun-r Ely-r I75n9?'? I amu/ imam nan AvaScale I 4tvw .7090 I Jam . 4 av!) 1/,va 111: Arall r477; Figure 340. Diversion Tunnel?Plan and Pro?le (Continued) 411 of the tunnel was determined by the hydraulic criteria of delivering a maximum flow of 3,788 cfs to the water users with the reservoir water surface elevation at 1,421 feet and a hydraulic gradeline elevation of 1,400 feet at The Metropolitan Water District of Southern California/ Department of Water Resources delivery point. With the reservoir water surface at elevation 1,380 feet, the tunnel and related system have to discharge downstream releases of up to 6,000 cfs, plus delivery to water users of 1,600 cfs. It also was necessary to design the shaft-tunnel intersection to permit 1969-70 floodwaters to pass unobstructed through a partially completed intersection structure. With the section of cut-and-cover tunnel required between the low intake tower and tunnel portal. Cut slopes at the portals were designed to be no stream release facilities installed, maximum release is reduced to approximately 8,000 cfs (water surface elevation 1,515 feet). In case of emergency, two fixedcone dispersion valves can be removed from the stream release facilities increasing the capacity to approximately 11,000 cfs. The energy dissipator at the end of the channel chute was designed to control downstream erosion. Energy is dissipated by use of a hydraulic jump, which mainly is controlled by downstream backwater conditions. Chute blocks and a dentated sill were added as further aids to stabilize and contain the hydraulic jump. Design of these facilities was verified by model 3. Design slopes parallel to or flatter than the average bedding plane of the formation in the cut. The tunnel's concrete lining was divided into three reaches, each with different loading conditions: (1) from upstream portal to high intake-shaft intersection, loads are hydrostatic head to ground surface and dead load; (2) from high intake-shaft intersection to Station 25+90, loads are hydrostatic head to reservoir normal water surface and dead load; and (3) from Station 25 + 90 to downstream portal, loads are hydrostatic head to ground surface and dead load (Figure 339). Rock load was taken as a uniform pressure around the concrete lining of one bore diameter of material. Concrete lining also was designed to withstand internal pressures to hydraulic gradeline during maximum diversion flow. The reach of diversion tunnel in the vicinity of the high intake-shaft intersection (Figure 341) was designed to constitute the initial stage of the shaft-tunnel studies. The dissipator structure was sized to operate with a discharge of 20,000 cfs. Final design of the outlet works, which was completed after the stilling basin was constructed, lowered maximum discharge to 14,600 cfs during diversion and approximately 11,000 cfs upon completion of the work. Tailwater for the jump is controlled by a downstream weir (elevation 1,136 feet) crossing. located at the new Lake Hughes Road dissipator floor was set at elevation The 1,090 feet to provide the necessary tailwater for the development of a hydraulic jump and to prevent sweep-out. Structural Design. It was anticipated that the enlength of the diversion tunnel would require structural-steel support. Due to the varying nature of material encountered, support loading varied. Support of the tunnel, except in designated reaches, was the responsibility of the contractor. minimum support was designated for a short reach at each portal. Special rib placement and shapes were required for the high intake-shaft intersection supports. An invert strut was designed for use through reaches of material exhibiting lateral yielding tendencies. An umbrella of structural steel was designed for both intake and outtire A portals to ensure stability of the cut faces and to provide safe working areas. The design also included grouted crown bars installed around the soffit of tunnel portal excavations to tie the umbrella structure to the portal face and to provide overhead protection during initial rounds of excavation. The upstream structural-steel umbrella was incorporated into the let 412 steeper than 1.67:1, with 15-foot-wide berms at elevation intervals of 40 feet. The resulting minimum equivalent slope for cuts involving one or more benches was approximately 2:1. Cut slopes were determined by the following criteria: 1. Stability analyses by the circular arc and/or slid- ing wedge methods. Comparison of design cut slopes with stable natural slopes in similar material in the immediate 2. vicinity. which was completed under the outlet works contract. No reinforcement was placed in the areas where concrete was to be removed at a later intersection, time. The tunnel intake structure (Figure 342) was designed to function both as a diversion during dam construction and later as a base for the low-level intake tower in the outlet works. The tower base was located a sufficient distance from the portal to be relatively free of slides and be a part of the portal approach floor. The critical design forces (hydrostatic and earthquake) on the tower were considered of sufficient magnitude to require the use of foundation piling around the perimeter of the tower base. Piling was designed for tension with the bearing floor serving as a pile cap and tie. A pile friction of 500 pounds per square foot was used. Primary concern for the channel section was that it carry the standard project flood. However, to accommodate the future stream release facility and to provide room for penstock valving, channel width was increased from 40 to 60 feet downstream at the bifurcation. The cantilever walls of the transitions, channel, and chute sections were designed to withstand within 2 feet of the top. Earthquake loading of O.lg was added. The structure was provided with a side drainage system. level backfill A an Iowa ?lbaw ,e U- -a 6? was: -a U-utva Figure 341. Hi 0w; y?Ixc-a Ana.- NI?ncll a-?a arm: _??andard [it?d/g run/?0] att'zan .. 01; gov: a of. ms 'oo 91-0,. ?as 70 ms 431 5 HIGH INTAKE SHAFT INTERSECTION Pug ?manna/Mr! Mn swarm ?ml-.3 L?p L: U-u?r "23793:? at: Graziaard '0'410 runna' [Urban 0 152-0 - Ilmf?arw-lv anacad {only. 413 1m f? away ~7.l 5r: 76-0167 '0 11a munyum/I: var dam]! 50w? gh Intake-Shaft Intersection ?7 and 5m 26016 00) A a 37132-7 r. are 4 0' "r14 4M0 run In .e-u ?7 SECTION R-R m4? VII-7 FPOM :rAn's- 1v ac ra :n 70:10 15 Na! in nu- A Sfrurfur-l ?my! 'a A: new. runnu 1 rwmu c\ I Hulda lunncl 34"6 bard me? nu. ?mum, mead. dclaw Iurm-l va a m: uni/brm/y Syatld. SEC ON A 91710: awe 7.. :u Iaadal7 '?nlAd uni faggmg? fun/77? CAL ran 57? (0406 I7 7?0 57? 20;Il.l7 10405 5 Bvlaw 4 av. {vJ? my", lumv/ A: nanny-r, .pcnr Scale . (an ?ue/e pl pm?gchvo c3245.; dun/oi 54517? ON 5-_5 No asmo mag 1 om?; . av pm: 1" ham lunr 1. 3.. ow 11-, 2 a for conga?, (team/nan and gmuhng noon 1 mama!? a pen/rem :ro?o -h shall be F-A..- ?4 mu 1 an SAFETY Neat-.1 - WATER Inn-m- mocv column" 0! win-u: unoukcn ammo: or nuuo- no noun? hum-u mun-la we" Inucn umston CASTAIC DAM TUNNEL HIGH INTAKE SHAFT INTERSECTION DETAIL 11/06 PNOFILE AN 0 SECTIONS 3% A Du rye/cu. ANB ?To- 21') Au "4 ?-0517 :ouu /1 Nu Scum Tl] in! fat/6.00 414 Figure 342 Diversion Tunnel Intake Structure u: 5 (put I I. .: your ooh?: 0 8 .. .- 4m tMl-t-ml u: aal? :m l'r?ln c-cw a 4 Duo-I by Ian(?all mummy33? (3-. . I . . .-. ?nu-a1 a _'9I3l-lIIIrv) yum! .I rm: - . or lrl? I I 3a ml Fwy-ohm . 3H. 1 - a mum.? 71w! ?Imm- .I 15-? arc-I." mu 'scux. coax wow pl xx .1 [lacu'53v'5?a'183W TAKE 3cmftp/CAL MW YE Au xaw x3713 mm. um .- a- my.? 5-717 .4 . drum- - ?c a- 4 0/ uni?w sn?vu 'vral nu I. nunSAFEIY - .- Nun-.1 - h) 0/ Ma?a unvvra - u-cnnuu ?1 nu CASYAIC an DIVEISIOI VUML INTAKE STRUCTURE run, not"; no cannon INYAKE FLAN A *?hn?ug? Although counterforts generally are more economiused for the energy dissipator, a gravity structure was designed to increase stability. This was achieved by designing the walls as tapered cantilevers with thickened bases. The addi- cal for walls of the height tional concrete required for this design increased the weight of the structure and produced the desired stability (Figure 343). Grouting. The design grouting program for the tunnel called for a grout curtain, consolidation grouting, and contact grouting. The grout curtain consisted of two rings of holes from 80 to 150 feet deep located near the dam axis so as to mesh with the dam grout curtain. Consolidation grouting consisted of rings of six holes 20 feet deep. Contact grouting was required throughout the length of the tunnel. Embankment tween the core and inclined drain and between the core and upstream shell. Various details of the embankment are shown on Figures 344 and 345. Analysis. Outlet Works Energy Dissipator and an inclined drain at least twice as thick would be specified for the same zoned embankment ters Description. The basic embankment section consists of a central impervious core flanked by pervious shells and a zone of random material contained within the downstream pervious shell. Internal embankment drainage is provided by an inclined drain, downstream of the impervious core, connected to a blanket drain in the channel and on the abutments up to elevation 1,450 feet. Protective filters are positioned be- Stability F!gure 343. Embankment stability was analyzed by the infinite slope, sliding wedge, and Swedish Slip Circle methods of analysis. Seismic forces used in stability analyses were approximated by applying a steady horizontal force acting in the direction of instability. The steady force was assumed at 0.15 times the moist or saturated embankment weight, whichever was applicable. The design properties of the compacted embankment materials are shown in Table 44. Design features providing protection against failure from seismically induced displacements included fil- as in nonearthquake area, a substantially increased impervious core width, and plasticity requirements for the core materials. These features were intended to prevent concentrated leakage and piping along any plane of differential transverse movement. A minimum plasticity index of 7% was specified for impervious core materials, resulting in an average plasticity index of core materials in the range of 10 to 15%. It is generally accepted that the higher the plasticity index of a fine-grained soil, the greater the ability to deform without cracking and thus the higher the resistance to a concentrated leakage. An extensive drainage system in the downstream shell and in the natural sand and gravel downstream of the Dam was provided to collect core and foundation seepage and transport it to Castaic Lagoon. A weir to determine seepage quantities was provided at the seepage outfall facility adjacent to the Lagoon. The impervious core was from unweathered (Zone IB) and weathered (Zone 1 A) Castaic formation materials obtained from required excavation. Additional Zone 1 A material was Construction Materials. selected 416 Figure 344. Embankment Plan V. I run. I I can? an m-oa (an! 51 I 7] 114,1;au - Anwm Vanna: Min. In! [nan[In mm?: My? 17a, ?mun?, upon] wand-In, 'pull Cf 1 5 Alulmml onan! Inn, \v-zumuu .r (an. any?: ml .n 5" a? Ilw/rwnanm? Ann- ?rum-? In ll.- ?R-f I A 21!.4 .no 1/ I ("warn lml-nlmon/ Mum-In, up! sum ,Manmum 5m um) - - .1 0 Ian lunnl/ I. Iron! I aum I \gnl Souncqc ?3 . 1m. Irv. mo. cam?X r, :umnu I he. .nunu- anuluu ?hw? I fun-I (?Vii .n Anu- lJu?lq:n nu ?nun, a! um nu (p'r ca-vumn my a. .- .run. 1mm nu-? LA to? an SAFETY Nun?q VATEI EIHANKHENT PLA- m; 417 Fig 0 re 345. Embankment Sections A 40' I Cusr (lav. [law 145:! ~w1 ISIS . no. an? [Jar pro far dc uh) 0mm?, Na U-Ios Mun Ic'y .pa/I Oragnvul graund Im. or. n- a fact/[Ho In: as n.n(nr and) (In. Inn (Mandola'y span unm/ 1 un I win: t/acnar" Ilnc (Foo/celcd) Grout l. Inc-relic" [Int 2,322; 525.39Jf'n?'um (5'53? CHANNEL SECTION 5m 43 .50 Sean :4 -Inn? In my Maud-rary Ipail v? Nw!? (lav OrIg/nol ground IInc\ an.m./ glaunt [pail Mund'Pary Mgr-dale?, Ina/I Am I Dunn: nu. I) In?: 15 (Normal In llcuvulld laundenanl 5? (mom-I In ?aundl 1617? Ann I mun: :snmnud Human?. (av/mated "caveman Iln. 'c ABUTMENT 574?16090 A an mun: .. Iarpll up slope In Idln? TA- . a! tuna 19 I. ABUTMENT SECTION Scolu? 3" OrI-nn? Na u-In4~7 for gram pInlNl canInvahgn acou- ppm-u, form": qraund m. :sno Luv ?on Cu" (In 1400\\ man I uu tumor-d M1- at group can I. a! 10 "Hwy! hum) malnnum 1?pPh ham '0 7O l. 7 ?(Ian m-nmum on. Inm [00? I. 70? - can.? hr Iunnol I ",ch TygIaal gray! for :ur'ainl a "a ran! n, a Mmunum a! In Ea?. IA nun-rum.? 7, Ian! guur pan-m [in cuuam (Bra/0:114 TypIeIl gnaw gun?. a; A and (arquua) JECTICN A-A ALONG 4X15 M-?aalary . apml an?: I - ton Mindallry /Cabeu Orly/nu! gown: (in. [7 "gunner. Ila. Elev (IOU 7o pan 4) Ann I nun-I'll Zone 1 a In: 9? (an. "nun: an an. a) EHIANKHENT ?zanc ll {Norm-l Ia Ole-valve! IICYIOII a-a PARALLEL an: 1 I 5 ?ea/Cl I - Ian' 0 II u?ma?n LL from selected borrow areas. Transition material (Zone 2A) and drain material (Zone 2B) are processed streambed sands and gravels from required obtained excavation and pervious borrow areas. Pervious shell material (Zone 3) is streambed sands and gravels from required excavation and pervious borrow areas. Random material (Zone 4) consists of terrace sands and gravels from required excavation and sandstones with some shale of the Castaic formation. Soil-cement for upstream slope protection was produced by mixing cement with excess Zone 2A material. Cobbles for downstream slope protection were obtained during the processing of streambed deposits for Zones 2A and 2B. Test Fill. A test fill was constructed at the Dam determine more adequately the reaction of Castaic formation materials to procedures being considered for construction of the impervious cores. Extensive field and laboratory testing confirmed that weathered and unweathered plastic materials from the Castaic formation would break down during excavation and compaction to form an impervious mass with a shear strength at least equal to that used in design. site in October 1966 to Settlement. Settlement of the zoned embankment caused primarily by consolidation of the central impervious cores. Consequently, laboratory consolidation testing and analysis concentrated on materials to be used in constructing the core. Because there is no proven analytical settlement approach known to determine that portion of core consolidation which occurs after completion of an embankment, a camber of approximately 1% of the fill height was provided to compensate for long-term embankment settlement. is Seepage Analysis. Seepage under the central impervious core is controlled by excavation for the core foundation to sound unweathered bedrock, by grout curtain construction, and by blanket grouting of fractured or sheared bedrock zones outside the area of the grout curtains. The design called for a main grout curtain 1 50 feet in depth, flanked by two curtains with depths of 70 feet, and two outside curtains with depths of 40 feet. Some of this grouting was deleted, as is discussed later. Seepage that does occur under the core should be concentrated in sandstone layers contained in the bedrock. Seepage through the impervious core, based on flow-net analysis, was estimated to be less than 0.25 cfs with the reservoir at normal pool. The analysis assumed a horizontal to vertical permeability ratio of 9 for the core and infinite permeability for Zones 2A, 2B, and 3. A vertical permeability of 0.01 of a foot per day was used for the core. Transition and Drain. The transition zones prevent movement of fine-grained core material into the surrounding pervious zones due to seepage forces, and the drain ensures drainage of the downstream shell. 418 Materials used for the transition and drains were processed by separating sands and gravels at approximately the '/z-'nch particle size and using oversize and undersize materials for drain and transition zones, respectively. To satisfy recommendations of the Department's Earth Dams Consulting Board, some smaller grain sizes were blended with the oversize material to prevent segregation when placing and compacting the drain zone. Specification limits for the transition (2A) and drain (2B) materials were derived to fit the anticipated processing scheme previously described. Upstream Slope Protection. Due to the relatively short period of wind-velocity recording and the topographic differences at the Dam site, a wind velocity of 60 miles per hour (mph) in any direction was used for a conservative determination of maximum wave height. The reservoir configuration results in a maximum fetch (length of reservoir over which wind can blow) of approximately 5 miles and an effective fetch (an equivalent length that a wave could traverse without being dampened) of Wave run-up was 1.6 miles. 60-mph wind, and a 3'X:1 embankment slope. The vertical wave run-up on riprap and smooth (soil-cement) facings was found to be 2.4 feet and 6.1 feet, respectively. Under conditions of wave run-up and the standard project flood maximum water surface, the riprap and soil-cement-protected slopes would have a freeboard of 9.7 feet and 6.0 feet, respectively. The soil-cement facing was assumed smooth to determine an extreme wave run-up condition; actually, the stairstep method of soil-cement construction an effective fetch of investigated for a 1.6 miles, results in a corrugated surface. A cement content of 8% by weight and a total soilcement thickness of 2 feet was provided. To aid drainage immediately behind the facing during drawdown of the reservoir, Zone 3 material containing less than 3% by weight passing the No. 200 sieve was placed within 10 feet horizontally of the soil-cement. The riprap alternative included in the bid documents apparently was not economically feasible and no contractor bid on that alternative. Dam Axis Alignment Changes. Slides occurring abutment during foundation excavation raised concern that the scheduled deep excavain the east (left) tions for the dam foundation at the easterly extremity Dam would undermine the stability of Lake Hughes Road and the ridge downstream of the Dam of the ( Figure 344) axis . To avoid this, the alignment of the was moved upstream by changing it dam from the 8,000-foot-radius curve to a line tangent to the curve running easterly at Station 45-1-20 (Figure 345). To further eliminate excavation in the vicinity of Lake Hughes Road and to take advantage of the more competent foundation, a second change was made along a 400-foot-radius curve to the northeast from Station 56-f 50 to Station 60 + 97 and then along a tangent line to the south end of the visitor's The alignment change construction overlook. to the tangent line at Station 45 + 20 departed from the original axis location at a very small rate. The locations of the various zones of embankment were brought into proper relationship with the new axis by varying outer and contact slopes slightly through a small height differential. The alignment change from the tangent to the 400-foot- radius curve at Station 56+50 would have been simple, except that there was insufficient room to extend the downstream Zone 2 A and the 2B chimney. At the time of this change, Zone lA at the east abutment was being built upward along a 1:1 foundation cut slope at its southern limit. The existing alignment also located Zones 2 A and 2B on the 1:1 slope. To correct this situation, Zone 1 A material was carried to higher elevations in this area until there was sufficient room to extend Zones tion of Zone 2A and 2B and also accommodate a sec- adjacent to the slope. Earth buttresses were added during construction to stabilize this area and an old landslide area on the right abutment. This construction included the earthwork for a boat ramp and parking lot on the left abutment as discussed later in this chapter. 3 Foundation Site Geology. The entire project area is underlain by the Castaic formation. Bedrock under the embankment is composed of approximately two-thirds shale interbedded with one-third sandstone. Silty shales and sandy shales comprise approximately 90% of the shale areas; clay shales comprise approximately 10%. Generally, the bedrock is not exposed at the ground surface, being covered by sand and gravel alluvium up to 85 feet thick in the channel, by terrace deposits up to 200 feet thick on the right abutment, and by landslides over 100 feet thick on the left abutment. Fresh shale is moderately hard. Bedding thickness ranges from to 1 foot. Some areas contain soft clay seams varying from a thin coating to '/ of an inch thick along bedding planes. Weathered shale is soft to moderately hard and contains gypsum in joints and along bedding planes. Fresh sandstone is soft to moderately hard. Bedding thickness ranges from 'X inch to 15 feet with most beds between 1 and 4 feet. Grain size ranges from fine to materials be placed on fresh, undisturbed, Castaic formation. This requirement necessitated the design of a cutoff trench. Spillway The spillway extends along the ridge line that comabutment of the Dam. It is approximately 5,300 feet long and consists of an approach channel, weir, transition, chute terminating in a stilling basin, and return channel (Figures 346 and 347). During the early design phase, several spillway locations were studied, including an alignment directly through the ridge into Grasshopper Canyon with a return channel down Grasshopper Canyon to Castaic Creek. Other alternatives included a dual-purpose stilling basin for the spillway and outlet works. Final design selection was based on economy and safety. prises the right Flood Routing. The spillway protects the Dam against the maximum probable flood (spillway design flood) which has a peak discharge of 120,000 cfs and a three-day volume of 86,600 acre-feet. There is 5 feet of freeboard above the resulting water surface. Design of the structures based on this flood is allowed to have stresses above normal. This conforms to the U.S. Army Corps of Engineers' design criteria. The l-in-400-year flood is the greatest flood for which design is based on normal stresses. This flood has a peak discharge of 61,000 cfs and a three-day volume of 57,300 acre-feet. Approach Channel. The approach channel conveys floodflows from the reservoir to the weir, limiting the velocities in the immediate vicinity of the upstream slope of the Dam. It was designed to minimize excavation costs and limit approach velocities to 5 feet per second in the unlined portions of the channel and 15 feet per second in the area where riprap is used. Hydraulic model tests of the original configuration '/j coarse, with fine grains predominating. The grains range from very weakly cemented to moderately well cemented with clay. Some beds contain hard sandstone concretions up to 5 feet in diameter. Tight, soft, clay gouges caused by shearing or faulting both across and parallel to bedding planes occur in zones that vary from a fraction of an inch to 2 feet in showed unsatisfactory flow conditions. Other wall alignments were tested for the approach walls. Final wall alignments were based on the results of the model studies. The control structure of the spillway conof an ungated, concrete, ogee weir with a crest elevation of 1,515 feet and net length of 360 feet. The weir length is based on economic studies which compare length of weir to height of dam embankment. The spillway during the maximum probable flood has a discharge of 78,400 cfs and a surcharge above weir crest of 15 feet. The spillway rating curve is shown on Weir. sists Figure 348. The weir was analyzed as a gravity strucand overturning was analyzed, and the magnitude and distribution of the foundation reaction resulting from the weight of the weir and the applied loads were determined. The weir structure thickness. ture. Stability against sliding Ebccavation. Removal of the overburden materials and highly weathered bedrock under the embankment was specified in order to provide a foundation at least as strong as the embankment materials to be placed on it. Another requirement was that Zone lA and IB structure is anchored to the rock foundation to increase its effective weight. For computing the stabil- 419 420 Figure 346. General Plan and Pro?le of Spillwuy are 11-00 4ca?3 bow-t2 r~ ?a Sal Owe Na U-lnl-Z 55 gar. t! 5:31.915 Chan/7:] frail! {fa 5-.0445 gal/u, .. ?mg re-d guitar, Nofe Croat [Ono/h - 160 PLAN scale: In 200? /or.9mol oragna AC 519 tor Allofoo? antenna? ?plan o?o N9 u-ur4?ni?h'd Me. a {In-?an woo. m: unuwuL; an Ir! r: W's D-achargt moo cr: n, 1 (my, 0N Sta/v angulnl 9rnuan\ luv-r! a?plaaell a" thann'l Am [.7100 tamp-clvd map-"ma yarn/d] our [In 15/500 - my? f? cnaln SECTION 4-4 Mu I. nu. ?ea-m hr!- In." A'u hind/gt] ranch Item SECTION 9-5 Na! Jun/- WA DISCHARGE NOTES 0.1., Ma u-nrc-I re, nun Eum la go [I'Pcr-faraloa Dram ann- are/n SECTION C-C Nut '1 :r-Iv ill! CAITAIC DAM SPILLIAY nun; run when? stilling basin at Station 51+00 (Figure 346). Hydraulic model tests showed the flow down the transition and the chute to be satisfactory for the max- imum discharge of 78,400 cfs, except for a short area action approached the top of the wall. Wall heights were increased in this area to maintain freeboard. where wave The spillway stilling basin was deflows up to the 400-year flood. It will traject all the discharges that exceed the 400-year flood to a point not less than 100 feet downstream. Freeboard to contain the hydraulic jump was the controlling factor in determining the wall height required. The length and radius of the flip bucket were chosen to yield a trajectory length of greater than 100 Stilling Basin. signed to Figure 347. Spillway and Stilling Basin and still all all dynamic, hydrostatic, and soil during spillway operation and during the design earthquake. Following standard practice, it is assumed for design purposes that there will be no seismic action during maximum probable flood feet to resist loads applied to ity, the critical sliding plane was assumed as the surface passing from the bottom of the upstream shear key to the bottom of the toe curve slab at the downstream end. Transition. The transition, immediately downstream of the weir, directs the flow into the 85-footwide chute with a minimum of turbulence. The flare angle for the transition was checked for contractions in supercritical flow. Various flare angles were tested in the hydraulic model. The design angle used gave the most satisfactory model study results. Chute. The chute extends between the end of the + 54 and the beginning of the transition at Station 25 it conditions. Return Channel. Immediately downstream of the bucket, a channel approximately 400 feet long returns all flows to Castaic Lagoon. Channel side slopes and floor are protected from erosion by riprap sized to resist return flows that occur when the flip bucket trajects the flow. flip Retaining Wall Design. The active and passive were states of earth pressure in the pervious backfill computed. Soil load was determined under the effect of earthquake loading. For various retaining wall design conditions where normal stresses were allowed, the resultant of the applied forces is within the middle one-third of the base. For improbable conditions (such as water in the spillthe time of an earthquake) where the allowable are increased by one-third over normal stresses, the resultant of the applied forces is within the middle one-half of the base. The approach, transition, and chute walls are of the way at stresses cantilever type and vary in height from 7 to 26.5 feet. Near the end of the chute, at Station 49-f-08, the wall changes from cantilever to counterfort. Counterfort walls vary in height from 26.5 feet at Station 49 + 08 to 70 feet at the start of the stilling basin (Station 51+00). The use of gravity, cantilever, and counterfort walls was investigated. Counterfort walls were selected on the basis of economy and ease for the stilling basin of construction. Floor Design. The impervious blanket in the aproach channel extends upstream from the spillway crest structure approximately 300 feet to create a percolation barrier to control seepage below and around the spillway crest structure. The blanket is a 3-foot- compacted, impervious material. Three feet of riprap was placed over the impervious blanket in the approach channel. The floor slabs in the transition and chute were designed in approximately 30- by 35-foot panels. Stability without the use of anchor bars and ease of construction were considered when the size and thickness thick, of the floor slabs were selected. All transverse contraction joints were provided with a cutoff and drains. The floor slabs were designed to resist uplift when the downstream transverse drain in a panel is plugged and no water is flowing in the spillway channel. Open-Cut Excavation. All construction slopes, except in the area of the stilling basin, are %:\. Near the stilling basin, the maximum construction slopes are 1/2: 1. which provides more stability. The extra slope stability was required because the excavation in the area of the stilling basin is deep and was left exposed for a considerable period of time. Permanent slopes do not exceed 2:1 spillway excavation nor Berms, berms are in general, are on the eastern side of the on the western side. l'/^:l spaced 40 feet vertically. wide and slope The from the toe to the heel of the berm. Where necessary, a pneumatically applied mortar was provided for erosion protec15 feet at 7/2:1 tion. Drainage. To reduce uplift, drainage was provided under the downstream end of the crest toe, floor slabs of the transition chute, and stilling basin, thus adding to the stability of the structure. The underdrain system consists of a drainage gallery, cross drains, wall heel drains, 422 and French drains. The final selection of alignment and Foundation. grade of the spillway weir, chute, and stilling basin achieved acceptable foundation conditions and satisfied all the hydraulic requirements. The upstream starting point placed the foundation of the weir crest structure in fresh Castaic formation that was not faulted nor otherwise disturbed. The location of the stilling basin was governed by locating the flip bucket in fresh Castaic formation. The stilling basin floor is 10 feet deeper than required for hydraulics to ensure that the entire foundation of the structure is in fresh Castaic formation. Outlet Works During the early design phases, several configurawere considered for the outlet works. These involved principally the intake tower and the downstream facilities. These studies included (1) a tions free-standing tower with its base at elevation 1,200 feet, (2) a sloping intake similar to the one at Lake Oroville for Edward Hyatt Powerplant, and (3) the final design that was built. The first two plans were eliminated because of topographic and geologic conditions. All plans considered multiple intakes to satisfy water quality requirements. The outlet works (Figures 349 and 3 50) utilizes the existing diversion tunnel to convey water under the Dam. Several modifications and additions to the diversion tunnel were required. A low intake tower (Figure 351) is located on the diversion tunnel intake structure. The tower is 15 feet in diameter, 100 feet high, and draws water from the reservoir above elevation 1,280 feet, minimum reservoir pool. A multiple-level, high, intake tower (Figure 352) is located above the diversion tunnel and is connected to it by a vertical shaft. An access bridge (Figures 353 and 354) spans from the right abutment of the Dam to the high intake tower. A fixed-wheel gate was placed upstream of the shaft and diversion tunnel intersection to shut off discharges through the low intake. A 19- foot-diameter steel penstock, located in the 27foot-diameter diversion tunnel, terminates at a bifurcation at Station 50+50. This bifurcation reduces and separates into two 9-foot - 6-inch-diameter penstocks. The stream release facility (Figures 355 and 356) is composed of these two penstocks and three smaller lines that branch from the left 9-foot - 6-inch branch. Fixed-cone dispersion valves and a pressure-reducing valve are used to regulate stream releases. The control valves are protected by butterfly guard valves. Turnouts just upstream from the bifurcation (Figures 357 and 358) deliver water to the various water users. These turnouts enter vaults containing guard valves which are operated either fully open or fully closed. This permits each water user to regulate the flow rate with his own downstream vaults are located downstream of the guard vaults. valving. Meter valve 423 30 87401 3pc .0 a yoa,.g aver Wag?'1'? Jignoun)? 351hoe no. mac moo (ll' a 3.74. 96,24 $516,354 55 2% 9 Figure 349. 4.13.121. Outlet Works?Plan and Pro?le Ev?ev mm a ran? wow 3 a. '6003 ,4 5. HM, ,lpuna E'er ?54412 7'09 a/ Mg?. Nofma/ ns? snag:- _chk Elev 49:: 5(7 510v ?9500 3 ?r a (he/a . ?I'cc 4.1709 l'drcurlwwmuu .m ?ow Irv/on aar- Erw'nq .a 3,7um. "no noon xuoo um mu ?ma r, at.) 19:00 - Iaa? ..: no -. . SAFETY - Nun-y WATER ~65 . 9/5 vac 5m vavoa scale - mo- sn :0 00 'm up; sun 1?7- . 'rT-J?z?va-?qu IJLVA - AIJJVS A. .. .c ?var: [Via f?l a ?1 a .0 05:31! In 04:49:!) 0., 034' and: Ham DMW 0mm o. -. 0-3 00-0: 1 ?r . I I gum ImaIBIS .. . . .120 mu, 600011, and-Q1 com: 4 DP 01; 1 303g ?oa -. . 03:09 0'5 00:01? me .001?, 5-035 ?00: 6o: 0, 00-0: no In 00'luna364.] yolc-y 00/, can 90E - m. Figure 350. Outlet Works?Plan and Pro?le (Continued) ~01: Imz?li A721 424 425 Figure 35?. Outlet Works?low Intake Tower gm 1299451 [295 so Trio/cruel! bun/WU E_Ivv reaa.aq 54.; 1219 no_ . 1 E_Io_v. 1?2,?ch .aan Ogtrann ?Iu?'vrm - w, a 51.. [2?5 00? mm- cry-a" 1239 an 4 Batu-hag UIOM . ,irzr.% . Gov. 5 rmgulh guy .1266 so A q. LOW INTAKE ELEVATION seal: 4 - Law- sup.? :ancr'!t) :1 In A. wage, LOW ?co/?Icpzr: REMOVAL scar: .1 . 1' IN TAKE _{Laow u?Tos-I Age? 0a 1234 ac . an.? a 5" bag 4? 5nd- Eu- ?05. an ana-w pr?p'l "lug-u 295 a 6? Law (In-k- Tr-nhroek Ow, 129a so r- Elly. [?95 50 mac. aa_ 0. 6? Cancun y. .91: o. r1mnv t\ - . ?1 12!: no er . 6 Gran! p1" gnu: (L Em 1115.00 scene/v . /Jym -nauv .n ?and.? from apt-[Ry I A a: SECTION 8-8 SECTION C-C ll? Era. [:70 ga_ mi 2.1. 4' 1:50.00 0"?ll a 14-109.: 1295 00 gm 1:55.09 1 no? (fawn-ad um mu prior a n- mm; mm yum CONCRE YE VAL Cu! aft 51!. I Cy! arr '50? :uarm, owpgum rull?ll . a 02:5?; . A J?'ld p-M jaonn ?nn nl? n-mua own-ma A naow I-uwu mum, mg I 1240.0 0 459/; o; sup?Dr; \Etlahny can 4m": hall 3 I A '1 bury?: hemp 5':Ir from urn" um: age-I: SECTION Nu Inn/e an,? . Cancun Dunn. In-" NOTES mun "gum-e. nlug h-aod an 'n 3 .- nou gnu/l a. . a at n. surfae's "up; an". Donor-l a. can u: u/u! SECTION sew. . I um nvu Immu an: WV IAIGN usnuc on outht no": INTAKE 426 1. 3n?, atrt'I-o" 'vnnl/ s" 01.9 Mll?7n' L1 5? H'Ja?n Figure 352. 1 Outlet Works?High Intake Tower u-ToIo-I than", :2 - a1 ~b~a "t?1lmahl at fog-wor- Ion interchon 1? you? 5' 5-. 0., 1' Approach ramp you, a 13?! I n. .u ?n Avg: mu.? .r9? .n ta? qu? u. .1 a'an gnu. a. po-raun a" . 96-40-6? an", . up; cum; 5 I/n asYouHana-1?441uv ?nun?Um,- pu- [With/1,! o'ln rm ha u: an, luv"! .1 ml-" 9.1. 12050pporug Seamudu?._ out sunv . . WATER n. UUAIYIIDIV mm. Ill' IIAICDI cnsunc mu ouuzv roux: HIGH INTAKE run nun norm: ??qu if- '75- 427 Figure 353. Access Bridge g-f 5'91}: 3" xu?,grmr . . xzsAMA. . DLlum in EIJSID Hula Conn-u Tip KIM/anon. ., 4. bras: I Vlrhul [:04 LL. 4% El 1455 1rd . It 1 ?Gud? Kmmg: 5 Fur a I?m-mu: ?mm ?1qu u-ns-a A Elts'rull :wndulOb 4w; u- a A Conduit Silt Typ- :1 Damn. um rm. :1 .353 Fur ?My, nlv- can A an: COLOR INHEK (1-1010. 5h! 27 5 sun uvu ugumu mun-am m; Lu.? ?mm? usurc DAI OUYLET nous am?. m. 155.]; HIGH INTAKE TOWER ACCESS same: Inamm lac-huh "qgad arm rm: GENERAL PLAN Tm WA 7 31113:? {gymnata? 428 Figure 354. High Intake Tower and Access Bridge 1 4? r- nan/.4.? ?r-ut luau," till 1 0 I 1 3? Law, ca v. ?tint/It gm. up; I of 0.40am? [nil-4 (1.14, - ?lled! A . rulnud 1M: 4 mm A. a: a. I/fr/l, I (I mm; mu, Ivy/f .Iul'lr/ll "In 7? ?4v - 11/4 I Figure 355. a? rr. 9: w: Stream Release Facility a; u: A I . mm?: rm?, um I llrl?l 4.1 _.Je 7 4? .9 @4151! 5a 0., an, nut lurlrnu rllr: a 3 FAAN STREAM RELEASE 1mm," . a? I- 04, min/bl! AND 5770670255 ran I 1" 5m:- u/uu (nu/til Irv/Ill] 5n 0., Inn-5 (In/m, Slur! Man); '1 I: In 3" "new .4 [Han-r: ?mu IF an a; z: 074-1; ta)" ,u 4 Mk! rc/itu 11/" H7932m,? 5/4 JI- vana_a_ . [In ?244: 5.1m?, uln - 14 mum, (m u: .1 . .14"ng Pa~1ll(l Em ?(tor r? Hm I 1m: A-A Ira/t - ta? nut/(In {Iv/q 0g (mm, ~n till In?: w! yarn: sun 0- av SAFEYY . Nu.? mun?w WANYIM oa mun ulna-mu 01va a cue.- no In'l um nuuv-n ?won-a "new? Jun? an. n: . .WAYEI I 1: urn an, IEIY DIAUCN DIVISION cum-c OAI oonn Ions STREAM RELEASE FACILITY GENERAL run AND sscnou I I .I ., -ul Jami? - lug-44,41 14:19;? . "mm- an ?(luau i131 *?xn gr 429 U-l 430 Figure 356. Outlet Works Stream Release 4 mm w-u Arr- . . An.- 4" r: 9 Figure 357. General Plan of Turnouis p. gnu Iv: of 3 train formld . - a (ram u?fjrm-d .J'farl'. whlru ?anH .. by a an?. .o n? m. u- ?Q?ell?l Chamf'r 1' all lur?ald V'vl"! SAFETY - an Nun-av WATER nag nag" I nz.pv whirl: u?wnmmawnm Inca-cu 4 Mme-av ?cm . u" Inn-cu omino- DA. OUTLET WORK. TURNOUT AND RELEASE FACILITIES PLAN .. Incl .u 9 431 Figure 358. Hydraulics. The the delivery system ments and Outlet hydraulic criteria used to design were based on contract commit- maximum deliveries as follows: Yearly Contract Maximum Delivery The Metropolitan Water District of Southern California (MWD) Castaic Lake Water 2,000,000 acre-feet 3,650 cfs 41,500 acre-feet 103 cfs 20,000 acre-feet 35 cfs Agency (CLWA) County Flood Control District X'entura Totals 2,061,500 acre-feet Design flow with reservoir surface The head 1,421 feet 3,788 cfs' at elevation 1,421 feet. make these deliveries was estab(reservoir water surface elevation available to lished at 21 feet — hydraulic gradeline elevation 1,400 feet at Department/MWD delivery point). From the just-mentioned criteria, tunnel, pipe, and turnout sizes were selected. The sizes of the turnouts are as follows: two 150-inch, one 132-inch, and one 78-inch for one 60-inch for CLWA; and one 30-inch for \'CFCD. The required port area per level at the high intake tower was 88 square feet, based on a velocity through the ports of approximately IS feet per second. This was based on operating two levels of ports for the MWD; maximum delivery. All natural inflow is to be measured for release to the downstream water rights owners. Flows up to 6,000 cfs are released at the same rate as the inflow. Flows above the maximum outflow rate of 6,000 cfs excess inflow can be safely released. Downstream flow releases are through two 96-inch, one 30-inch, and one 10-inch fixed-cone dispersion valves, and one 8-inch pressure-reducing are stored valve. 432 until this To minimize cavitation problems, the fixed-cone dispersion valves will not be operated less than 10% open. The 8-inch pressure-reducing valve can discharge O..') to 8 cfs between minimum total net head of 156 feet and 320 feet of maximum static head. Reservoir drawdown time from elevation 1,515 feet (maximum water surface) to elevation 1,400 feet is about 14 days. Maximum discharge with the fixedcone dispersion valves removed is approximately 11,000 (\CFCD) * Works Turnouts A cfs. was required to prevent the passing of fish from the reservoir into the system. The fish screens are movable and cover any two adjacent ports in a vertical row. The units travel inside the trashrack on rails with a clear distance of at least 6 inches between the trashrack system and the screen. Openings with movable covers are provided to allow the screen unit to pass protruding hardware on the outside of the fish barrier tower. The fish screens consist of stainless-steel mesh with %-inch clear opening attached to a frame of stainlesssteel tubing. The mesh was designed to withstand 5 feet of differential head, and the frame was designed to withstand 10 feet of differential head. Structural Design of High Intake Tower. The superstructure arrangement was chosen to accommodate mechanical and electrical equipment and to satisfy structure requirements. in design of the operating deck, five live load sources were considered. In design of the intake tower, six loading cases were considered, including seismic forces with tower dry and with v\ater both inside and outside the tower. San Andreas design earthquake spectra, as developed by the Department's Consulting Board for Earthquake Analysis, was used I ! ' determining design accelerations for the tower. For determination of design base moment and shear, 60% of the San Andreas spectral acceleration was used. This reduction was based on consideration of the seismic response of the foundation material and on the relative importance of the high intake system and the consequences of its failure. The calculated modal periods of the tower were 0.78 of a second, 0.12 of a second, and 0.045 of a second for the first three modes. The 8% damping factor used in the seismic response analysis resulted in acceleration factors of 0.25, 0.33, and 0.30 for the first three modes. The tower was treated as a moment-deflecting cantilever. For the controlling seismic case, the base moment and shear are a result of the dead- weight inertial load of the tower and superstructure, internal hydrodynamic load, and external hydrodynamic load. Dynamic and hydraulic model studies, conducted at the University of California at Davis, verified the design assumptions (see Bibliography). The intake shaft was designed to transfer base moment and shear to the foundation rock. A joint was designed for the shaft at elevation 1,262 feet to prevent transfer of the moments to the tunnel. Tower and shaft dead weight were included with the maximum moments from flexural design. Hoop reinforcement as the basis for was designed to provide tensile reinforcement to resist diagonal tensile stresses associated with moment and shear in horizontal planes during an earthquake. Placement of shotcrete was specified after the completion of each 6 feet of shaft excavation, thus preventing air slaking and minimizing the need for lagging. Excessive lagging would reduce the effectiveness of the shaft concrete contact with the rock. A consolidation grouting program also was specified to fill voids and structural defects in the surrounding rock and between the rock and shaft concrete. Trashracks protect all the tower intake ports and the traveling fish screens from logs and other debris. Maximum spacing of the trashrack tubes was set at 4 inches, based on the maximum-size debris that can pass through downstream facilities. Stainless steel was chosen because of its low maintenance requirement and long service life. High Intake Tower Access Bridge The high intake tower access bridge, in combina- tion with an approach ramp, provides access to the Castaic outlet works high intake tower from the near- by crest of the Dam. A curved bridge alignment was required to permit an efficient arrangement of equipment in the tower. This alignment also located the abutment a safe distance from the top of an adjacent cut slope and allowed for an economical design of the abutment. The bridge is 504 feet long with a superstructure consisting of four simple spans of welded-plate girders acting compositely with a lightweight concrete deck. The girders are supported by the high intake tower, reinforced-concrete piers which are socketed into rock, and a reinforced-concrete abutment. The superstructure is highly articulated to accommodate ex- treme earthquake movements. It provides a clear roadway width of 16 feet between barrier railings. Design was in accordance with the 1965 AASHO specifications and with the State of California "Bridge Planning and Design Manual". The bridge was designed for a live loading of HS20-44 and an alternative loading of two 24,000-pound axles, 4 feet apart. Instrumentation Castaic Dam instrumentation consists of 15 pneumatic foundation piezometers, 16 pneumatic embankment piezometers, 18 hydraulic piezometers, 13 open-tube piezometers, 8 embankment slope indicators, 9 abutment slope indicators, 69 embankment surface monuments, 15 embankment soil stress cells, 7 embankment accelerometers, 1 foundation accelerometer, and 2 accelerographs. Monuments also are located along the top of the spillway walls and on other concrete structures. The instrumentation was designed to monitor pore pressures and vertical and horizontal movements, as well as acceleration response of earth motion and dynamic stresses resulting from seismic activity (Figure 359). Seepage is measured at the end of the embankment drainage system and in the spillway drainage gallery. Lagoon As previously mentioned, the Lagoon was initially a borrow area immediately downstream from the toe of Castaic Dam. Maximum elevation of the floor of the Lagoon is 1,125 feet. A minimum of 2 feet of fineCastaic grained, mandatory, spoil blanket was required over most of the Lagoon to control seepage. Where Castaic formation was exposed, no cover was required. The west side of the Lagoon was excavated to enhance the recreation development. The control structure for the Lagoon is a 170-footlong by 350-foot-wide concrete apron under the new Lake Hughes Road Bridge. A rectangular discharge channel near the east abutment of the Bridge carries streamflows up to approximately 12 cubic feet per second. A standard Parshall flume with a throat width of 2 feet and a depth of 1 foot - 6 inches was installed near the upstream edge of the apron for flow measurement. Downstream releases are recorded by a flumerecording well. Flows greater than the capacity of the Parshall flume pass over the entire 350-foot width of the apron. The control structure is designed to pass the standard project flood discharge from the spill- way. Details and sections of the lining of the approach channel are shown on Figure Downstream shown on Figure 360. sion control consists of riprap as ero361. The bridge abutments form a portion of the control structure walls. Cantilever walls of varying height flank these abutments upstream and downstream to complete the control structure walls (Figure 362). 433 434 Figure 359Jud-?44 July?? ?Wo .1 Km)? Instrumentation Plan and Section LEGEN Iowan-Hf Iyyouh: pagan-aw 1' (le? purely-w run-r .5149: macaw onto/lam ?my: Qumran Puma-M 7? [m (no: 9 5109? (Mutatb? mMIafm/ Ian [no ,4 1:61): a? mm: I fur/kg, - ad?? a new. 1444 page .Tur or: :vawar pan/w gm; mar rpm/ac ma) 3 i: I, monumonfl?la?l Four (lot um ?if 5m :oIIArn-crrl pan! or (my[Io-e 1:4: . MMWW (lay :m Diva 4-.03-11 ,0th ?IxEB/wlu- Zane; (ll-r ?go *1 gm .I. A .2,an\ zone/I 7:154? oar: an: mum.? rpm,? er (m Immr tamed/'1 ?fl/'mt/I' wumi?f ?((110111 Immune?! mcomramon?r Faun? flan ?cw-mm. Aw- 0,an navy: (all ?mup Janet/0n no: Mum" men In: vi! N011 r? 7) Manny,? (rev (my (/40 or 1 If ?00 [meafro alto-roller! [me A 17 574 424.! Ire/e ?sm?tL'?um Anal, 59,! tr?j Wm (Ill . n? . In . a? a Axr42:12 . ow ?5 Harrow lwcowohon mu - SAFETY - - Nun-q - "In uvn new: I Hutu-nu (- A and/.10 Inoroaah Chan" 0/ 4W4 APEA 5col.? 1- . paa' U'l03-7 Figure 360. Castaic lagoon Control Structure Sections 1? fltahnq 5 cw (-9 Abu?me?f I Elev H1705 - 5000' 1505? 9a7' 657' ?rm 4-x. 4. _4 14.5 In - . Elev 1/46 45 00" 1/4500 ?4,25 Anni-on Elev 7r?qtnol - ., arcane 1/40 1 I I 1. Aggro. 5m. 0/ 5' cue ar?orno/ arouno ~40 Elev llJG.?a?? 0' .- ?01 on: few/)1" (rmpal. r1 Ari . Jag??/I? ?10 are! . Eu? 5 u? 1a., .1 1-94 4?1 See L'c/o I .vaq :1 a7 .7 I Amt." ?12:7 too black Di." 51:, I 25 7 \\-1nvo me a . .Cho, 20 - r- fee black - A Zanrima?lma/ a' Channel be. black 2 04 Ann-SECTION A-A 59: One u- 107-/ In men - Ewan/1:; Anufmanl A pumq wall oanneahon '5 9,5 day/men! ?Ia- 3.. Derm/ on u- 107- m. 1,50 77 WALL l? 1130' 55 . 11E 4+900 60 00' 750 4 scale 6m. 1/50 55 Elev 1/50 a: ,gpm, a, E/e. lasso Incl qr?Oun 59:11.75 :0 Force: gnu, he, I 11:: Agar-n. Le. a! no. a Elev 14/ 10~ [a 5/5. rqe_za_ 14,. an. 1 (12? Eco/1heel attack 7mg .1 3 CUBIC ard: MI. ?1 mgr/Ir? black a. 51.. 1/257 :0 4 Aaron foe bloc/r . SECTION 8-5 A Se 0 U-lD7-l 5: olqu?- PM, CHANNEL HEEL BLOCK Scale l' 1' cm cone: 1 Payee Chalu?a/ In?? 6 ?9 CC Dren?; /5 CV 1115 5/9. ?4500 ?E/ew Hlaoo ounc- Glue and 5 1 . awn our-an I: 4? 50 I 2 Measured anachoroa cabana! wa I-zharmel elpana/on jdl?f Joe acre/I rv Dug u- 107- 5 Elev/(14647 Illo? 20 Elev ul . Apron Tee! 0 act! a. Channel roe ?man I nh?fv an)! clack . a w. ?orrw 7: 7?4 Perv/a. 1 Jan: rm Fbvea oar-an 1 I ?mxl?i? 4. sex a APPON . a Em. "1:00 . HEEL BLOCK I rv- - 1 Eu.? 112.5 7 I - I - ?Chonncl hea? b/DCk? SECTION c-c Se:- qu u-mrl APPON TOE BLOCK REINFORCEMENT seePW-ap Iype fir? 112:7 0 Wu? A A. +100 15: 50_ 150' [10' 150' I150 550 i c? yam: .51" - - Nuts-.1 WATER 4' xuvr um . nwonu Acumen HKSY IIANCN hwy/m, 4 ?sum on. A AFTERBAY CONTROL STRUCTURE See pent! ?21? 0.19 707': .. - Anran lac clock 0 no me 9? 40mm heel block 404 mm SECTIONS nun-nu.- 435 lav-gm an"? .4 u-wv-e 74 57 Ra?? .. Twl' I m- -2 I 1.41:: ll ncg? 1.05.209 >o?p9z ?up: rm Bxyhi. ?25 .n I . ?rm? w?rniw $.33 ll i r? 2 r.l.l+ 11": w. .F 1.4. r. a How: ?-14 1.. 5 a. ?Ilpahml $3 45534 305519 9.9 ll Figure 376. ^ •» i.fESEflVOJ/> ANTELOPE LAKE"^ ABBEY BRIDSE R/tSERVQM 1968 ; LJtKE o/tftyjM^ V DWARO HYATT POWERPLAlir m.r M^ THEHItALtrO pomeitPLAHT %^-*^ { 9\.THERMALirOv^J , - J CANAL CALHOUN PUMPINt PLAtfT / \ ^ TRAVIS .^ef)MP(He PLANT ^^J^^ PUmPlHG A/OffTH BAY AQUEDUCT ^^-.-r / / DAMS AND RESERVOIRS 23 I Lake Antclopr Lake-Lake Davi>.._ Abbey Bridge. DiBie RefugC' Lake Oroville Thermaliio DlverBion Pool Fimh Barrier Pool Thermalito Forebey .... Thermaliio Afierbay.... Cliflon Court Forebay.. Belhany Lake Del Valle San Lui« ONeiU Forebay Loa Banot . _, Liiile Panorhe Bullet Silverwood Lake Lake Perrit Pyramid Lake Elderberry Forebay Ca»taic Lake Total* SS.' 22.566 84.371 45,000 16.000 J. 537. 577 I.(.328 580 1 1 ,768 57,041 28,653 4.804 77.106 2,038.77 1 56.426 34.562 13.236 21,800 74,970 Ml 452 171.196 28,231 323.702 6.848,617 12.700 3.700 1,297 460 2.235 554 18.600 -^—1968 CORi PUUPINi YEAR OF SERVICE STATISTICS RECREATION RECREATION AREAS FISHING ACCESS SITES [mm savsnwaao 1' 1.4x: 972 bum/v I Fowypumr ?36 TEMCMPI corroIv . Paws? ANT AFTERBAV -. $277555 I 4.0. Eauowsra/v 2 Paw/Iva PLANT mm; 64? .l97/3 I 9 PUMPING PLANT a .3- w? I ER mac: . 050 -Pu - A I968 11 warp/ya mama fare-nun 1 Kr . IDS WENA $197 FOP AY WING PLANT I nt- 245 ?01: PLANT IN6 Pl,? nvom 7 -. Pr/uu/o . LAKE . 1? DEN PUMPING AND SIWTDOTN PUMPING PLANT 2~ .736 PLANT POLONIO PUMPING PLANT 3 COASTAL 982 1? 1'3? 4 ?1 SARA SAN LUIS oa/sPa 8 POWERPLANTS [3 Toni Mun-mum cum. Arum-1 Norm-I Flow Pawn Enugy Numbu Sun: (cum: Gener-Ior OulpuI or Hug lul per llulow-II- N-mz Unn- (reel) Ierond) (know-II.) hour-I Hy-n 5 410/575?l 14.550 570.750 2,475,000,000 4 05'100?l 15,900 119,500 351,000,000 I 99 327? 13.120 424.000 5.572 222,100 170,000,000 I 140 I 1.17 15.000 115.000 000 1.41:: 1 119 '00 1,003,000,000 Pyr-nud 2 740 3.100 157.000 1.001.000.000 Cum: 101.1 7 1.053 10.400 1.250.000 sm- 3.092 714.000 1.457.000.000 s-n Luu 01mm. I 730 5.900 41.000.000 snore ?35?3000-000 nun-11m. ma mun-mm u-m hz-dl 2) The CIly or L5. Angelrl Ora-umlnl oI w-m ma Power wIll conllrucl ma over-I: - 1.250.000-kunw-ll Powerpl-m Ind lupply Ih! P701001 mm pow" .450 "In" mun-10m lo 110111 I 213.904- lnlo-v-n pnwupl-m In: 51.1: In I POWEPPL ANT ?455.41: LAGOON 5.57" mesa/p. 1.4x: LU.) ANGELES SAN DIEGO A 1.01 av, 22 PUMPING PLANTS Tom] M-umum Delmn Tau] Annual Non-11.1 Flow Molar Energy Number Sun: (cum: Rum. at Head [eel per (harn- (know-ll- Name Uruu ((001) Itcond) power) houn) Edward (pumped nor-3e) 3 500 5,510 519,000 455.000,000 "muggy.? 3 135 1020 9,000 120,000 91.000.000 North Bay Aquzducl: Calhoun - 5 33 120 500 3.000.000 Tun/Is 5 0 120 900 5,000,000 3 443 as 3? loo I4 000.000 Soth Hay Aqueducl: 55th 9 545 330 27,750 155,000,000 1351 v.11: 4 0/3812 120 1.000 2.000.000 II 244 10.303 333.000 1.355.000.000 a 99 327?2 11.000 504.000 51-1. 511.". .. 5,752 254,000 313.000.000 Dal Ammo. 5 113 13.200 240.000 7.100 130,000 507,000,000 Buenn 10(3 205 5,049 135,000 745,000,000 When" 913 233 4,593 140,000 797,000,000 9<3 513 4,410 305,000 1 751.000000 A. D. Eamon-Ion" 14(3 1,925 4.095 1,040,000 5,915,000,000 5 540 1,330 113.200 547,000,000 Aqueducl 231 3,123 93,500 445,000.000 5 55 450 4,050 20,000,000 Bldg" H111. 5 151 450 10.500 55,000,000 Dev-1'. Den 4 409 125 13,000 51,000,000 Slwlaolh . 4 331 125 5,500 41,000,000 P5151115 .. 4 910 125 15,000 101,000,000 Cln-l Toul 9(3 10 21.300 35.200 Sm. Shlr:_. 10,900 17,440 95.000.000 Tat-I. Sure Share a: 13,601,000000 MII-umurn Ind m-nmum pumpml z) annurn Ind m-nmum nun-c hudl. 3) lncludel one Iplre unn. 483 PROJECT (METRIC 23 DAMS AND RESERVOIRS AQUEDUCTS 268.8 1,363.60 6,396 16 44 0.72 14.52 70.36 2SS 16.1 1,741 41.8 69.60 1.093 26.89 235 >.29 131 21 904 16 1 1.6 43 12,802 i.669 59.363 536 15,291 STATISTICS UNITS) RECREATION • <>^ RECREATION AREAS FISHING ACCESS SITES OS KseHyojR •SERVOtR AND RATING PLANT COASTAL BRANCH w % SAN LUIS oeispo POWCRPLANT _j;,-«fc - i THIS BOOK IS DUE ON THE LAST DATE STAMPED BELOW BOOKS REQUESTED BY ANOTHER BORROWER ARE SUBJECT TO RECALL AFTER ONE WEEK. RENEWED BOOKS ARE SUBJECT TO IMMEDIATE RECALL MAY 2 MAY 2 6 RED 16 1971 JUN ,?g?flqi' 1/1934 :q JLI 06? 1 ?387. . I 1087 II yr: LIBRARY, UNIVERSITY OF CALIFORNIA, DAVIS Book Slip?Series 458 - •re California Bulletin. . D*?pt . C2 A2 PHYSlCAt SCIENCES LIBRARY m of Water Resources piI'lll?u: ???furl: II ?Ian I?31th .I.