STATE OF CALIFORNIA I 6 CALIFORNIA NATURAL RESOURCES AGENC. DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Oroville Darn No. 1-48 County Butte Type of Dam eartth? Type ofSpillway Gated concrete weir and ungated conc. weir Water is 138 feet below spillway crest and 159 feet below dam crest. WS 763 ft Weather Conditions Sunny and mild Primary contacts Dave Sarkisian and Paul Dunlap from Bill Dickens and Joe Eades, Contacts Made OFD - Roy Kroll, Brent Lamkin, Sean Dunbar, Project Geology Reason for Inspection annual inspection Important Observations. Recommendations or Actions Taken a The primary reason for this inspection was to prepare for the Oroville Complex 2014 scheduled to start in June 2014. 0 As recommended in the previous 12 Report plan for long-term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented." is working with DSOD to develop a course of action. 0 A contractor is making repairs to the inoperative river valve outlet system (RVOS) to restore the low level release capacity. A longer term project is being developed to increase the reservoir drawdown capacity for dam safety purposes. a Staff should continue to monitor the long standing mid-slope seepage at the left side of the slope. The ground cover should be trimmed low to facilitate monitoring activity. A means of monitoring the extent of the seepage area should be implemented. a Visual monitoring of the irregular rock wave protection along the upstream slope should continue. Wave erosion appears to be disturbing the rock and causing it to move down slope in some areas. a The trees and brush along the left and right sides of the flood control outlet chute walls have been cleared, as requested. - Crest roadway paving is scheduled, but will likely be delayed until next year. a The field office will attempt to complete the radial gate seal repairs (gates 6, 7 and 8) this season. Conclusions Based upon my information review and my inspection, the dam, reservoir. and appurtenances are judged safe for interim use pending restoration of adequate drawdown capacity, completion of Category 2 radial gate- recommendations, and implementation of a plan for long term monitoring of the Oroville Dam phreatic surface. Observations and Comments Da_m The surficial asphalt cracks along the crest roadway remain. See photograph 1, for example. The surface is satisfactory for continued use pending completion of an upcoming repaving project that has been delayed for some time. The survey monuments along the crest were well marked and in good condition, and the shoulder remains stable after having been repaired a couple of years ago. See photograph 2. The embankment, groins and abutments appeared to be stable. See photographs 3 through 6. Rodent and vegetation control appeared to be satisfactory. Brush along the upstream and left groin has been cleared, as requested. Inspected by WPennington Photostaken? Yes No 4/10-11/2014 jj'r' CC for owner/BOOK Date of Report 4/29/14 jriown 1261 (Rev. 10/09) Sh Name of Dam Oroville INSPECTIC DAM AND RESERVOIR IN CE. .IFIED STATUS Dam No. 1?48 Date of Inspection Observations and Comments Spillway DWR 1261 (rev. 10109) The usual seepage area at mid?level on the left slope was less prominent due to the lower than usual reservoir level. See Seepage paragraphs below. The rock along the upper part of the upstream slope remains uneven in some areas, probably due to wave action. The slope should be visually monitored for excessive movement, as has been done in the past. The rock breakdown noted at some locations is not excessive. House and the right gallery were not inspected, but will be during the upcoming inspection. The inspection team walked the left gallery, the bypass tunnel, and the S-block. Following the gallery inspection, the team traversed the Emergency Exit Tunnel to the powerplant. The first water in the left gallery was from a foundation drain at Elevation 798. This is typical. The reservoir level was near Elevation 763 feet. No new concrete cracks, or any significant offsets were observed along the gallery. As noted before, several circumferential cracks are located at grade transitions. Mineral buildup continues at a number of lcations. See photograph 7, for example. An attempt should be made to clean these areas to allow better monitoring of flow and crack geometry. Conditions along the Emergency Exit Tunnel appeared to be unchanged, except fortemporary rerouting of the drain pipes. As previously requested, the drain system should be checked for blockages. Paul Dunlap mentioned that repairs are planned. Bidwell Canyon Saddle Dam: The reservoir level remains well below both embankments. No signs of instability were observed. The graveled crest remains in good condition. Vegetation and rodent control remain satisfactory. The toe drain outfall was clear and dry. Parish Camp Saddle Dam: The reservoir level well below the embankment. The gravel crest roadway remains in good condition. No signs of instability were noted. Vegetation and rodent control remain satisfactory. The rock placed in the erosion gullies along both groins was intact and stable. Conditions along the upstream and sides of the Flood Control Outlet (FCO) appeared to be unchanged from last year. The approach training walls remain stable and in good condition. The service (upper) deck is shown in photograph 8. No signs of structural distress were noted, and the concrete was in satisfactory condition. A contract crew was in the process of repairing minor breakouts along the deck joints. Nothing unusual was observed along the radial gate hoist deck, except for a possible nest inside the hoist cover at the south end of the deck. See photograph 9. The field staff will check this. The radial gates were inspected by looking down from the hoist deck and by observation from accessible locations along the trunnion deck. The gates appeared to be in satisfactory condition, except for the usual detritus and water that collects along members with blocked drain holes. See photograph 10, for example. Regular maintenance is needed to keep these areas clean to control corrosmn. Radial gate seal leakage is still a problem, even at gates 1 through 5 where the seals and associated operating hardware have been replaced. Seal repairs at gates 6, 7, and 8 are Sheet 2 of 14 Name of Dam Oroville DAM AND RESERVOIR IN CE. . IFIED STATUS 1-48 Dam No. 4/10?11/2014 Date of Inspection Observations and Comments Outlet Seepage DWR 1261 (rev. 10/09) scheduled this year, but may take a while to complete due to resource limitations. A number of Category 2 recommendations resulted from the September 2012 radial gate inspection by the HDR. Inc. The recommendations will be scheduled and completed on a priority basis. Nothing unusual was observed during a cursory inspection ofthe radial gate trunnions and trunnion anchors. See photograph 11. Ultrasonic testing of the trunnion beam anchor rods has resumed. No spalling was observed along the bridge bents. The diagonal crack on the left bridge abutment may have extended somewhat, but this could not be determined for sure due to the faded paint. The paint should be reapplied and observed regularly. The emergency spillway weir appeared to be in satisfactory condition. No signs of instability or concrete problems were observed. The discharge chute was observed from the FCO decks and from the opposite side ofthe river. Conditions appeared to be normal. The walls were well aligned and appeared to be stable. See photograph 12. A complete walking examination of the discharge chute will occur during the upcoming l2 inspection. The river outlet system remains inoperative pending completion of a project to restore the discharge capacity. The area was not entered because of the ongoing work. It is strongly recommended that the area be made accessible to the Team. Oroville Dam: Flow thru the toe weir was normal for the reservoir level, about 9 gpm. The seepage flow in the galleries was within historical trends and remains relatively low. Measurement weirs located along the drain gutters can be used to the check the flow over a specific reach of the gallery. Seepage within the emergency exit tunnel appeared to be normal. As previously requested, the drain pipe system should be repaired. Paul Dunlap mentioned that repairs are planned. During the July 2013 DSOD inepection, the team noted a small spring in a tree lined channel located from the right groin. The area around the small undercut pool was wet for a short distance. As the reservoir rises next season, the location should be watched to see if the reservoir level influences the flow. The long established wet area at mid-slope on the left end ofthe dam remains. A small saturated area was observed at the left groin. See photographs 4 and 5. The field staff should continue to monitor the area for unexpected changes in the seepage pattern or flow quantity. A means of monitoring the extent of the seepage area should be implemented so that year to year changes can be recorded. In addition, the ground cover in this area should be kept low to facilitate the monitoring process. Bidwell Canyon Saddle Dam: The lake level was well below the embankments. The toe drain outfall at the west embankment was dry, as expected. The foundation seepage that migrates from Miners Ranch Reservoir to a seepage area upstream from the south embankment remains distributed over a wide area defined by trees and brush. A long standing concentrated seepage at the head of this area was flowing about ?12 gpm. This seep should be kept clear of vegetation to allow visual monitoring of the flow. No other seepage areas were observed. Sheet 3 of 14 Name of Dam Oroville INSPECTIC DAM AND RESERVOIR IN CE- .IFIED STATUS Dam No. 1-48 4/10?11/2014 Date of Inspection Observations and Comments Instr. Parish Camp Saddle Dam: The lake level was well below the embankment. No seepage was observed. The latest monitoring data on file is the December 2013 which covers the period from 10/1/12 to 9/30/13. The following comments are provided. Oroville Dam embankment: Three active piezometers are functional. These are P-37(upstream transition), and A mentioned previously, they appear to provide little useful information, but will be read until they no longer function. The last FERC Part Report states that plan for long-term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented.? is working with DSOD to develop a course of action that will be presented to the Board. Survey monuments are located along the upstream and slopes and along the crest of the dam. Crest settlement remains minimal. The maximum movement being about 9-inches at station 53+00 since 1969. Settlement and displacement along the upstream and slopes remains normal and appears to be stabilizing. Bidwell Canyon Saddle Dam: Settlements and deflections remain small and normal. Parish Camp Saddle Dam: Settlements and deflections remain small and normal. The instrument program for Oroville Dam is satisfactory on an interim basis, pending completion of a program to monitor the embankment phreatic surface, and a review of the GPS approach for monitoring embankment deflections. The saddle dam instrument program remains satisfactory. Based on my field inspection, my discussions with field staff, and my review of the available data, Oroville Dam, and the saddle dams, appear to be functioning normally. DWR1261 (rev. 10mg) Sheet i of 1?4 DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1?48 Date of Inspection 4/10-1 1/2014 1. Asphalt cracking continues along crest of the dam crest. A contract to repays the crest will probably be delayed until next year. 2. This is atypical survey monument along the shoulder of the crest road. The restored shoulder at right remains stable. DWR1261 (rev. 10109) Sheet i of 1__4 INSPECTIO DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date of Inspection 4/10-11/2014 xii?" 3. The upstream side of the embankment appeared to be stable. Some rock displacement has occurred along the upper slope. This is most likely due to wave action. These areas have been noted for a number of years and should be observed for changes from time to time. DWR1261(rev.10l09) Sheet 6 of 14 1F DAM AND RESERVOIR IN CE. STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection 4/ 1 0-1 1/2014 . .- I The left gallery access was under the control of a contractor performing work on the river outlet valves and related 1 equipment. A temporary access door and high power vent fan have been installed. The vent system is said to disrupt the normal air?ow in the galleries. 4. This View of the embankment shows ongoing contractor activity at the left gallery entrance and the long standing seepage area along the left side of the dam. The seepage area extends along the embankment within the approximate limits of the double arrow. A saturated area was observed along the groin, dashed arrow. No standing water was present at this location. See photograph 5. DWR 1261 (rev. 10l09) Sheet 7 of ?14 INSPECTIO DAM AND RESERVOIR IN CE. STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 4/ 1 0?1 1/2014 5. The dashed arrow is in the same location as the dashed arrow in photograph 4. This location was saturated, but no flow or standing water was observed. The approximate upslope extent of the seepage area on the embankment is depicted by the double arrow. Sheet 8 of 14 INSPECTION or: DAM AND RESERVOIR IN CERTIFIED STATUS Name ofDam Oroville Dam No. 1-48 Date 4/10-11/2014 Accelerometer well. 6. This View shows the left side of the embankment, repaired shoulder at the crest, and the crest accelerometer well. The shoulder material is said to be a mix of road base and cement. It has completely arrested the erosion around the survey monument points and has stabilized the edge of the asphalt roadway. DWR1261 (rev. 10mg) Sheet A Of A 3F DAM AND RESERVOIR IN .FIED STATUS Name ofDam OFOVille Darn No. 1-48 Date of Inspection 4/1 O-?i 1/2014 7. This calcite deposit in the left gallery obscures the actual conditions at the concrete surface. This makes changes in seepage and crack/joint geometry difficult to assess. Joints with a significant mineral accumulation should be cleaned from time to time. Sheet 10 of 14 1F DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8. This View looking left along the Flood Control Outlet Structure shows standing water left over from recent cleaning prior to the repair of small concrete popouts at transverse joints. 9. The hoist deck at the Flood Control Outlet Structure appeared to be well maintained. A nest of some sort appeared to be located just inside the hoist cover at the arrow. Telltale straw was observed at the seal. DWR 1261 (rev. 10mg) Sheet 1 1 of ?14 7F DAM AND RESERVOIR IN .FIED STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 4/10-11/2014 10. This View taken looking upstream from the trunnion deck of the Flood Control Outlet shows a typical radial gate. Note the accumulation of water and detritus a the bottom of the gates. The water was due to concrete washing on the deck above, but this also occurs when the seals are leaking. The drains are apparently blocked and should be cleaned out at least once each year. Sheet 12 of 14 3F DAM AND RESERVOIR IN CEI STATUS NameofDam Oroville Dam No. 1-48 4/10~1 ?1/2014 Date of Inspection 11. Typical conditions along the trunnion deck are shown. The trunnion beams appeared to be in satisfactory condition. The deck was recently cleared to remove the accumulated detritus from bird activity. The orange paint is used as a telltale to check for breakouts along the bridge bents. Problems have not been observed for many years. Sheet 13 of 14 DAM AND RESERVOIR IN CE. STATUS Namecham Oroville Dam No. 1-48 4/10-11/2014 Date of Inspection v: 1..- .J - . 12. Brush behind the left and right spillway walls has been removed as requested. The walls appeared to be well aligned and the drains were dry. The chute floor appeared to be in satisfactory condition. A closer inspection of the walls and chute floor will occurs during the upcoming inspection. Sheet 14 of 14