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Qavec) $222)) EsmEmm Ewe) End )1 (:02)th {he )prrap Emmet). ups 32:2) The 2:2) 2) 9:22:22) ngE?) 2232) abuimem E73): 533L333 ma?a Emaiiam Emceming radar): 22.22222): 2222 9222222)"). \2 232)) by 02-22. Ens-paci?c 222222 133225))? )2 Egg) (3222252))? E2232). 8392292)) I Gate. a a R. 2222) 2222)). 2.223)) aha-)2)- I INSPECTION DAM AND RESERVOIR IN CERT, ZED STATUS Name of Dam San Antonio Dam No. 1008-2 Date of Inspection 11/14/2016 Observations and Comments Spillway Seegage The approach, control section, and exit were clear of concerning debris. The concrete comprising the entrance, weir, invert, channel walls, and flip bucket exit appears in satisfactory to serviceable condition. Overall, the panel joints to both the walls and invert were adequately-aligned. I noted minor spalling between the wall joints, and the previously repaired patch located at the first left wall joint in the spillway approach has failed. This damaged area has not been repaired as requested during the previous inspection, and needs to be repaired. Longstanding cracking on portions of the spillway?s invert has been noted in previous inspections. The areas of concrete deterioration that include cracking and minor loss of bond between the cement paste and aggregate on the spillway?s invert appeared unchanged as compared with previous inspection photos and reports. The areas of deterioration appeared to be caused by a sulfate attack of the water seeping in the spillway?s drainage system. The spillway appears to be in overall satisfactory condition, and there are no concerning conditions that require immediate action. The spillway invert, walls, and overall condition of the concrete needs to be monitored for any changes in condition that may affect the operation of the spillway. The outlet consists of an approximate steel pipe, which is controlled valve and a valve. None of the outlet controls were cycled during this inspection. The upstream valve and the valve were last cycled during the November 5, 2015 maintenance inspection. DSOD requires that th_ system be cycled at least annually and in our presence every three years. Mr. Moss agreed to fully cycle the upstream and valves in the upcoming months in order to fulfill the annual cycling requirements, and arrangements need to be made to cycle the valves during the next maintenance inspection. The outlet tunnel was inspected and was found to be well lit, welt ventilated, and in good condition. Areas of mineral buildup were noted, and the tunnel was well aligned with no sign of instability or distress. The usual areas of typical seeps were dry as a result of the drought conditions and low reservoir water ievel. The new seep located that has developed along the left wait as a result of the collapsed drain pipe appeared to be less than the 05 (Photo 2). The Agency is scheduled to install a new trashrack in 2020. The trashrack will be attached to the inlet structure with the new relocated threaded rods that were installed in 2015. The new rods outnumber the original design and Mr. Moss agreed to submit the trashracks design drawings once they become available, and if we determine that the work is essentially an in-kind replacement, it will be considered routine maintenance and will not require an application. The Agency re?lined - lineal feet of the outlet pipe starting at the outlet iniet (Sta. 0+00) to the -valve (Sta. 4+96) in 2015, and the video inspection and final report of re-iining the outlet pipe was covered in a separate memorandum. The remaining 604 lineai feet of the steel outlet pipe is planned to be re-lined in phases by the end of 2026. The face and right groin were dry. The toe relief drains 1-9 were all dry. The left abutment/groin has longstanding seepage conditions and a total of 34 horizontal drains were installed when the dam was construCted and supplemental drains were installed in 1969 and 1984 in order to collect and combine the seepage for measurement The left groin was walked and the majority of the horizontal drains were dry due to the low reservoir water DWR1261 (rev.10/09) Sheet 2 of 7 DAM AND RESERVOIR IN STATUS Name of Dam San Antonio Dam No. 1008-2 Date of inspection 11/14/2016 Observations and Comments level. Horizontal Drains 55 and 75 had an approximateiy flow of 0.5 gpm, and Drains 53, 74, and 73 were dripping. The Parshall flume located at the toe of the darn that measures the combined flow from the relief and horizontal drains was dry (the water from the horizontal drains dissipated before arriving to the flurne). There are two 10-inch underdrain pipes that daylight at the end of the spillway, and these drains were dry. The Agency submitted a preliminary work plan dated June 15, 2016 for the repair of the collapsed drain pipe located at the toe of the dam and just to the right of the outlet tunnel. After our initial review, the Agency is further developing the method to fill the annular space between the original drain pipe and the new and smaller diameter drain pipe. The Agency will submit the new work plan to the Field Engineering Branch after they demonstrate a successful method to fill the annular space. The instrumentation at this darn consists of 35 embankment survey monuments, 60 spillway survey monuments, 13 outlet tunnel survey monuments, 82 open well and hydraulic piezometers, 34 horizontal drains, and 10 relief wells. The latest instrumentation submittal was dated June 30, 2016 and covered the period through December 2015. Piezometers and Open Wells Eighty-two open well and hydraulic piezometers were reported and the data was assembled into the following ten groups: upstream channel foundation, channel foundation, right abutment and "bench area foundation, upper left abutment foundation, tower left abutment foundation, channel area foundation/embankment contact, upstream shell zone, central imperious core zone, outlet conduit beneath core zone, and the drain and shell zone. Piezometric pore pressure plots covering the period through December 2015 were provided. The maximum reservoir water level during 2015 was El 646, 134-ft below the spillway crest. The reservoir's low water elevation was 128?ft lower than the level used in the 1970 stability analysis, and correlating the 2015 piezometer readings to the design phreatic surface is questionable. All of the functioning piezometers responded-to the dropping of the reservoir?s water elevation. Piezometers 3, 18, 104B, 1058, 110, 111, and 112 that are installed in the drain and shell zones indicate that the drain continues to function effectively. An April 21, 2004 DSOD Memorandum of Design Review by Shawn Jones identified four critical piezometers to monitor. Piezometers Nos. 1048, 1058, and 18 in the shell and drain should remain dry and Piezometer No. 24 located in the embankment should maintain a pore pressure less than 670 feet. The three shell/drain piezometers have remained dry, and Piezometer No. 24 exhibited malfunctioning behavior and no data has been plotted for this piezometer since mid?2014. The dry conditions in Piezometers Nos. 1048, 105B, and 18 indicate that the zone of pervious gravel material of the core is providing adequate drainage. The piezometers located in the central impervious core zone continue to gradually decrease with the reservoir water level, and this appears to indicate that the core continues to dry with the historic low reservoir levels during the current drought period. The teft abutment drains were flushed in late-2011 and lower left abutment open wells 106A, 1068, and 106C showed drops in water levels of up to 15 feet, indicating the effectiveness of the drains was reduced before the flushing. The water levels in these three open wells continue to remain constant with the low reservoir water level. The report identified several hydraulic piezometers that appear to be malfunctioning, and some of Sheet 3 of 7 DAM AND RESERVOIR IN IED STATUS Name of Dam San Antonio Dam No. 1008?2 Date of inspection 11/14/2016 Observations and Comments these hydraulic piezometers may be at the end of their useful life. Piezometers 1A, 6A, 10, 11A, 13A, 15, and 26 appeared to show maifunctioning conditions. Piezometer 19 appeared to be coming back to ?life? in 2012, and had erratic behavior during the 2011?2012 reporting period. The piezometer data does not indicate any unsafe conditions involving the dam. The submittal reported data on 82 piezometers and it is recommended to simplify the report by focusing on specific piezometers judged most critical to the monitoring of San Antonio Darn. Also, piezometers that have malfunctioned should be properly abandoned or replaced, if necessary. Although it is recommended to simplify the report, the Agency should continue to internally review and evaluate all active instrumentation and data. The Agency must submit any proposed changes to the instrumentation network or submittals to DSOD for review and approval, prior to proceeding. Left Abutment Horizontal Drains There are 34 horizontal drains in the left abutment and 10 of these drains are not routinely monitored, as they are dry. The ieft abutment seepage responds to the reservoir water eievation and the flows had a moderate spike after the 2003 earthquake event and then another rise in 2006. The flows then had a gradual decrease since 2006 to below pre- 2003 levels and then started a gradual rise in 2011 after flushing. The total peak left abutment drain flow in 2015 was less than 1 and is due to the historic low water levels. The November 2011 flushing of the left abutment drains resulted in increased flows and dropped the water level in three ieft abutment open wells. The effectiveness of this flushing will become more apparent with larger hydrostatic reservoir head and long term data. Relief Wells - The total measured flow from the relief wells has historically been near 2 or less since 1993. The total peak relief well flow throughout 2015 was negligible. Parshail Toe Flume This flume was installed in 2000 to measure the horizontal drains, relief wells, and toe seepage. The peak flow in 2001 was approximately 100 gpm. The flume in was dry during the entire 2015 reporting period. Embankment Monuments There are a total of 35 embankment survey monuments and 21 are located atong the crest and embankment. The last survey was performed in April 2016. Overall, both the horizontal and vertical displacements are small and no unusual movements or concerning trends are indicated by the survey data. The largest horizontal and vertical movements between the 2015 and 2016 surveys was approximately 0.03-f- which is within the error tolerance of the survey. Outlet Tunnel Displacements The outlet tunnel survey frequency has been established at five- year intervals since 2002 and after significant seismic events. The last survey for the outiet tunnel was performed in March 2012 and the next survey is scheduled for 2017. The displacement since 1993 has been essentially flat and no concerning trends or unusual movements are indicated by the data. Spillwav Monuments - The vertical displacement of the spillway slab is grouped into Upper, Middle, and Lower survey stations and is subdivided into left, center, and right sides of the spillway. There was a period of ?questionable survey methods? and data between 2000 and 2005 was omitted. The data showed unexpected movements from year to year; however, the overall maximum movement since 1993 has been 0.1 feet (1.2 -inches). The movements appear to be influenced by the reservoir water eievation, which in turn may indicate the movements may be effected by the underseepage. The movements of the spillway are not a concern at this time, but continued close Sheet 4 of 7 x' DAM AND RESERVOIR IN IED STATUS Name of Dam San Antonio Dam No. 1008-2 Date of inspection 1 1/14/2016 Observations and Comments monitoring of the spillway is warranted. The instrumentation data indicated that this dam is performing adequately. The existing instrumentation and their monitoring frequency are judged sufficient at this time. DWR 1261 (rev. 10/09) Sheet 5 of gm yam mm mm? .. ?ma. m??w 2&3 a $9.3 amaze. gmwmim. .6wa 9n .m ?d?mg m. ?ng . In,nv ..Ma .. 21.5sz .I/f/Jz . w. I .. Zn?. m. . x/mw/ . . .. (Dal. 1:Sam?. mzm? Ex ?NSzP-Emimp mm mm- RE-SERVQR m: gag-Ni may ssrm?zrusx Neamaof'D-am 512:3?) Antmiia . - Dam" No 113138me D-aia' Gf'i'nape'e??n f1 75114129? ?31 aitiack. 'waan 4. The. sp'allie?: Gamcrates and exmsed $333 rei-hf?rmmani ?i'ogaieci? an. the Eelft: spiin-ay wa? near the: $3331 3-way appraaeh has: bear-1, refpaired as: veg A Mk ?xi $215.21 (rev; mag Qxx' QC Em"? - REEIDIJRIJES EGENCI 0E EE QEMS IIEI QEERYIFIEEI 51.5.3 Name: .EI-jaajm. Dam NE. 1.533538% WEE Sam I Type; 80:3wa CEIICIEII, End ?53 EI-IEI 1'34 water Weather Cigar 'WE'rm {xi??'gif?i MEI KEIEE EIIE PEI-I LEIIE WEI-II MICE EI Items. 7E I EIEE-I I?eihfbm?mE?-?f Epili' WEE. '2 IE IIEI-I "E?iig?m?m TEE IE IE IIE 2328IIE EIE EEI. IEI ?has?. EII End the. Ef IE planned IE EE IE End 2028 28. 2015; February 2 20. 3E IE4 the Ef? EIEE II-EE memorandum WEE- EI- PIE-2E. IEEI IE EI- EI IEE dam. TIIE- AgEncy {fazed IS 2-8. IEI EEII I25 by the FIEIE EIIE EEIE EIIE I TEE WEE.- Hang. EE 2518-5-63? I?I'gh't' Emma WEE. me Sign (If Er TIIE IIE grams IEE EEI-I EIIE has?5251 {Rem - INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam San Antonio Darn No. 1008-2 Date of inspection 05/12/2016 Observations and Comments Spillway Outlet The approach, control section, and exit were clear of concerning debris. The concrete comprising the entrance, weir, invert, channel walls, and flip bucket exit appears in satisfactory to serviceable condition. Overall, the panel joints to both the walls and invert were well-aligned. I noted minor spalling between the wall joints, and the previously repaired patch located at the first left wall joint in the spillway approach has failed. This damaged area has not been repaired as requested during the previous inspection. Longstanding cracking on portions of the spillway?s invert has been noted in previous inspections. The areas of concrete deterioration that include cracking and minor loss of bond between the cement paste and aggregate on the spillway?s invert appeared unchanged as compared with previous inspection photos and reports. The areas of deterioration appeared to be caused by a sulfate attack of the water seeping in the spillway?s drainage system. The spillway appears to be in overall satisfactory condition, and there are no concerning conditions that require immediate action. The spillway invert, walls, and overall condition of the concrete needs to be monitored for any changes in condition that may affect the operation of the spillway. The outlet consists of an approximate steel pipe, which is controlled valve and a valve. None of the outlet controls were cycled during this inspection. The upstream valve was last cycled on January 4, 2016, and the valve was last cycled on November 5, 2015. DSOD last witnessed the cycling of the valves on November 5, 2015. The outlet tunnel was inspected and was found to be well lit, well ventilated, and in good condition. Areas of mineral buildup were noted, and the tunnel was well aligned with no sign of instability or distress. The usual areas of typical seeps were dry as a result of the drought conditions and low reservoir water level. This seep appeared to be less than the 1.0 flow that was observed during my November 5, 2015 inspection. The Agency has completed the installation of the .stainless steel threaded rods that have been anchored into the concrete of the inlet structure with an epoxy adhesive that had been pre- approved by me and discussed in detail in my November 5, 2015 inspection report. The Agency plans to design a trashrack almost identically to the original design, except the trashrack will be divided into multiple units, instead of the current single unit design. The trashrack will be attached to the inlet structure with the new relocated threaded rods, which outnumber the original design. Mr. Moss agreed to submit the trashracks design drawings once they become available, and if we determine that the work is essentially an in?kind replacement, it will be considered routine maintenance and will not require an application. Mr. Moss informed me that the Agency has scheduled the installation of the new trashrack in 2020, and he will send 0800 the design plans once they become avaiiable. The Division received a letter dated November 20, 2015 that enclosed a September 28, 2015 video inspection of the_ outlet pipe, and a fetter dated February 11, 2016 that enclosed a February 9, 2016 final report for re-lining - ineal feet of the outlet pipe starting at the outlet inlet (Sta. 0+00) to the - valve (Sta. 4+96). The remaining - lineal feet of the steel outlet pipe is planned to be re?ned in phases by the end of 2026. The video inspection and final report of re- lining the outlet pipe is covered in a separate memorandum. Sheet 2 of 7 INSPECTION DAM AND RESERVOIR IN ilED STATUS Name of Dam San Antonio Dam No. 1008-2 Date of Inspection 05/12/2016 Observations and Comments Seepage The face and right groin were dry. The toe relief drains 1?9 were all dry. The left abutment/groin has longstanding seepage conditions and a total of 34 horizontal drains were installed when the dam was constructed and supplemental drains were installed in 1969 and 1984 in order to collect and combine the seepage for measurement The left groin was walked and the majority of the horizontal drains were dry due to the low reservoir water level. Horizontal Drains 55 and 75 had an approximately flow of 1 gpm, and Drains 53, 74, and 73 were dripping. The Parshall flurne located at the toe of the dam that measures the combined flow from the relief and horizontal drains was dry (the water from the horizontal drains dissipated before arriving to the flume). There are two 10?inch underdrain pipes that daylight at the end of the spillway, and these drains were dry. The small collapsed area of the embankment located at the toe of the dam, just to the right of the outlet tunnel, was inspected (Photo 2). On June 3, 2015, crews investigated this area by excavating with a backhoe, and found that the bottom one-third of the 12-inch asbestos bonded corrugated metal drain pipe (CMP) had been lost to corrosion. This drain pipe travels 125-ft into the dam foundation and drains the right side of the outiet tunnel. A June 11, 2015 video inspection of the CMP was performed, and the metal pipe was found to be severely corroded such that the bottom 25% of the CMP was missing for a length of approximately_ upstream of the collapsed area. The remaining CMP appears sufficiently intact to provide working space for repair. The Agency submitted a preliminary work plan dated June 15, 2018 for the repair of the drain pipe, and the work plan is currently under review by the Field Engineering Branch. The instrumentation at this dam consists of 35 embankment survey monuments, 60 spillway survey monuments, 13 outlet tunnel survey monuments, 82 open well and hydraulic piezometers, 34 horizontal drains, and 10 relief wells. The latest instrumentation submittal was dated September 24, 2015 and covered the period through December 2014. Piezometers and Open Wells Eighty-two open well and hydraulic piezometers were reported and the data was assembled into the following ten groups: upstream channel foundation, channel foundation, right abutment and bench area foundation, upper left abutment foundation, lower left abutment foundation, channel area foundation/embankment contact, upstream shell zone, central imperious core zone, outlet conduit beneath core zone, and the drain and shell zone. Piezometric pore pressure plots covering the period through December 2014 were provided. The maximum reservoir water level during 2014 was El 657, 123?ft below the spillway crest. The reservoir?s low water elevation was 117?ft lower than the level used in the 1970 stability analysis, and correlating the 2014 piezometer readings to the design phreatic surface is questionable. All of the functioning piezometers responded to the dropping of the reservoir?s water elevation. The central impervious core piezometers had drops in levels that were much slower and stayed higher than the reservoir?s water level. The higher water levels in the core piezometers are expected since the core has low permeable materials in which the pore water dissipates at a much slower rate. Piezometers 3, 18, 24, 104B, 105B, 110, 111, and 112 that are installed in the drain and shell zones indicate that the drain continues to function effectively. An April 21, 2004 DSOD Memorandum of Design Review by Shawn Jones identified four critical piezometers to monitor. Piezometers No. 1048, 105B, and 18 in the shell and drain should remain dry and Piezometer No. 24 located in the embankment should maintain a pore pressure less than 670 feet. (rev. 10/09) Sheet 3 of 7 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam San Antonio Dam No. 1008-2 Date of inspection 05/12/2016 Observations and Comments The three shell/drain piezometers have remained dry and Piezometer No. 24 has maintained a pore pressure near 654 feet throughout the reporting period. The dry piezometers indicate that the zone of pervious gravel material of the core is providing adequate drainage. Higher than desirable readings in the lower and upper left abutment piezometers were recorded, and in particuiar Piezometer 101 had higher levels than the reservoir water level during 2014. The left abutment piezometers appear to corroborate the seepage conditions that exist aiong this abutment. Open Well Piezometers 109A and 110A, located at the toe between outlet tunnel and left abutment, continued to have artesian conditions excess pressure above the ground surface) during the 2014 recording period, but their conditions were less than during 2013 and continue to remain within historical norms. The left abutment drains were flushed in late~2011 and lower ieft abutment open weils 106A, 1068, and 106C showed drops in water levels of up to 15 feet, indicating the effectiveness of the drains was reduced before the flushing. The water levels in these three open wells continue to correspond to fluctuations in the reservoir water elevation. The report identified several hydraulic piezometers that appear to be malfunctioning, and some of these hydraulic piezometers may be at the end of their useful life. Piezometers 1A, 6A, 10, 11A, 13A, 15, and 26 all appeared to show malfunctioning conditions. Piezometer 19 appeared to be coming back to ?life? in 2012, and had erratic behavior during the 2011-2012 reporting period. The piezometer data does not indicate any unsafe conditions involving the dam. The submittal reported data on 82 piezometers and it is recommended to simplify the report by focusing on specific piezometers judged most critical to the monitoring of San Antonio Dam. Also, piezometers that have maifunctioned shouid be properly abandoned or replaced, if necessary. Although it is recommended to simplify the report, the Agency should continue to internally review and evaluate all active instrumentation and data. The Agency must submit any proposed changes to the instrumentation network or submittals to DSOD for review and approval, prior to proceeding. Left Abutment Horizontal Drains There are 34 horizontal drains in the left abutment and 10 of these drains are not routinely monitored, as they are dry. The ieft abutment seepage responds to the reservoir water elevation and the flows had a moderate spike after the 2003 earthquake event and then another rise in 2006. The flows then had a gradual decrease since 2006 to below pre- 2003 levels and then started a gradual rise in 2011 after flushing. The total peak left abutment drain flow in 2014 was 1 and is due to the historic low water levels. The November 2011 flushing of the left abutment drains resulted in increased flows and dropped the water level in three left abutment open weiis. The effectiveness of this flushing will become more apparent with larger hydrostatic reservoir head and long term data. Relief Weils The total measured flow from the relief wells has historically been near 2 or less since 1993. The total peak relief well fiow throughout 2014 was negligible. Parshall Toe Flume This flume was installed in 2000 to measure the horizontal drains, relief wells, and toe seepage. The peak flow in 2001 was approximately 100 gpm. The total peak flow at the flume in 2014 was 5 and dropped to zero my mid-2014 due to the drought conditions. Sheet 4 of 7 INSPECTIOF DAM AND RESERVOIR IN CER ilED STATUS Name of Dam San Antonio Dam No. 1008-2 Date of inspection 05/12/2016 Observations and Comments Embankment Monuments There are a total of 35 embankment survey monuments and 21 are iocated along the crest and embankment. The last survey was performed in March 2015. Overall, both the horizontal and vertical displacements are small and no unusual movements or concerning trends are indicated by the survey data. The largest horizontal and vertical movements between the 2014 and 2015 surveys was approximately 0.04-f- which is within the error tolerance of the survey. Outlet Tunnel Displacements The outlet tunnel survey frequency has been established at five- year intervals since 2002 and after significant seismic events. The last survey for the outlet tunnel was performed in March 2012 and the next survey is scheduled for 2017. The displacement since 1993 has been essentially flat and no concerning trends or unusual movements are indicated by the data. Spillwav Monuments The vertical displacement of the spiliway slab is grouped into Upper, Middle, and Lower survey stations and is subdivided into left, center, and right sides of the spillway. There was a period of ?questionable survey methods" and data between 2000 and 2005 was omitted. The data showed unexpected movements from year to year; however, the overall maximum movement since 1993 has been 0.1 feet (1.2 ?inches). The movements appear to be influenced by the reservoir water elevation, which in turn may indicate the movements may be effected by the underseepage. The movements ofthe spillway are not a concern at this time, but continued cloSe monitoring of the spillway is warranted. 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The appeared in satisfactory condition, having minor surface corrosion and pitting along the valve seat. Surface pitting on the interior of the valve?s body was observed and this appeared to have been caused by cavitation. A coffer dam was constructed with approximately 2-ft of freeboard around the intake structure, and the reservoir surface elevation was approximateiy 0.8-ft above dead pool. Crews had removed the bottom portion on the west side of the trashrack to gain access into the structure (Photo 1). A total of .stainless steel threaded rods had been anchored into the concrete of the inlet structure with Hilti epoxy adhesive (Photo 4). I had approved the use of this epoxy adhesive in previous communications with Mr. Moss since the anchors primarily resist shear forces. The new trashrack design was almost identical to the original design, except the trashrack will be divided up into multiple units, instead of the current single unit design. The trashrack will be attached to the inlet structure with the new relocated threaded rods, which outnumber the original design. Since the repair is essentially an in-kind replacement, it is considered routine maintenance and will not require a repair application. Mr. Moss toid me that he would send DSOD the as?built plan sheets for the new trashrack once they had been fabricated and installed. The MCWRA performed an inspection of the entire iength 0? steel outlet pipe on September 28, 2015. The steel pipe has a thickness of and the valve body of the valves has a thickness of at least -. The overall condition of the pipe was found to be in serviceable condition. The interior surface of the steel pipe had corrosion in areas where the original coating had chipped off. The majority of the chipped off areas were circular in nature, and the majority of the chips were less tha in diameter (Photo 6). The deepest pitting within the steel pipe was reportedly measured at at intermittent locations. For safety reasons, I did not inspect the interior of the outlet pipe because it is considered a confined space and a confined space entry permit had not been arranged. was able to inspect the outiet pipe at the entrance to the inlet structure, and although I did not note any pitting, I did observe areas of mild surface corrosion where the lining had chipped off the pipe (Photo 6). Mr. Moss told me that the Agency had contracted Techno Coatings Inc. with an emergency purchase order to remove the existing coating and prepare the surfaces by sandblasting, filling in the pits with epoxy, and applying two coats @6-8 mils each of Devoe Devran 133 epoxy coating, for approximately .lineai feet. The areas scheduled to be covered are - upstream and of the - valve (including the disc) and of the inlet structure. The emergency purchase order was issued due to the impending rain season. Mr. Moss told me that the Agency intends to recoat the entire length of the interior of the outlet pipe, and if there is no rain forecast during the repair, the Agency was prepared to increase the scope of work. Mr. Moss agreed to document what work was completed and submit plan and schedule to repair the remaining portion of the outlet pipe. At my request, the Division received a letter dated November 20, 2015 from the MCWRA enclosing a DVD containing video surveys of the 84?inch diameter outlet pipe that was performed on September 28, 2015. I will cover the review of the video survey and the extents of the repairs Sheet 2 of 7 mum-Wm m2 ?mw? Mum-?mm?. wM-??xW-?mm? zm?m??gamm -M-.-..-. . @me x? 4/ fa ..- 59/ U?m ?mm-M ma:- .S?ww. 5555 ?255 5525 55125535 Earth 5555' 5'5. 355 33 3'5 5555 3:513 5535555 . . . $135 55315555555 5:355:53?; 555.553 3% .. 5555553553 35555 555555555. 3 3?35 . 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Mr. Moss showed me a small collapsed area of the embankment which was located at the toe of the dam, just to the right of the outlet tunnel (Photo 7). On June 3, 2015, crews investigated this area by excavating with a backhoe, and found that the bottom one?third of the 12- inch asbestos bonded corrugated metal drain pipe (CMP) had been lost to corrosion. This drain pipe travels 125~ft into the dam foundation and drains the right side of the outlet tunnel. A June 11, 2015 video inspection of the CMP is scheduled to investigate the condition of the pipe. The Agency needs to contact the Division after the completion of the video inspection in order to discuss options for repair. Spillway The approach, control section, and exit were clear of concerning debris. The concrete comprising the entrance, weir, invert, channel wails, and flip bucket exit appears in satisfactory to serviceable condition. Overall, the panel joints to both the waits and invert were well-aligned; noted minor spaliing between the wall joints, and the previously repaired patch located at the first left wall joint in the spillway approach has failed (Photo 5). This damaged area has exposed reinforcement and needs to be repaired. Longstanding cracking on portions of the invert has been noted in previous inspections. observed areas of concrete deterioration that included cracking and minor loss of bond between the cement paste and aggregate on the spillway?s invert (Photo 4). A fairly well-defined reaction front was observed at the spillway?s invert joint from underseepage at the spillway invert joints (Photo 3). Ahead of the front the concrete was normal, and behind the reaction front is where observed the deteriorated concrete. I also observed that the steel corrugated pipe at the outfall to the underdrain located at the exit of the spillway has dissolved and the ribbed contours that are casted into the concrete are ali that remain (Photo 6). The areas of deterioration appeared similar to an external sulfate attack. The spillway appears to be in overall satisfactory condition, and there are no concerning conditions that require immediate action. The spillway invert, walls, and overall condition of the concrete needs to be monitored fer any changes in condition that may affect the operation of the spillway. Outiet The outlet consists of an steel pipe located in a concrete reinforced tunnel that is controlled by an upstream valve and a valve. During this inspection, a 5 habitat flow was being released into the Salinas River. Due to regulatory release requirements with the National Marine Fisheries Service the upstream and valves were not cycled during this inspection. Mr. Moss stated that he needs NMFS approval for a bypass release plan before Agency can schedule a cycling of the valves. The upstream - valve was last cycled on September 19, 2013, and the - valve was last cycied on April 10, 2012. DSOD last witnessed the cycling of the valves on April 10, 2012. Mr. Moss requested for special accommodations in order to cycle the outlet system. I reminded Mr. Moss of our policy: the outlet vaives need to be cycled at least annually, and in our presence every three years. I requested Mr. Moss to acquire the necessary permits from the other agencies in order to comply with our policy. The outlet tunnel was inspected and was found to be well lit, well ventilated and in good condition. Sheet 2 of i1 INSPECTION OF LIAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam San Antonio Dam No. 1008?2 Date of inspection 05/05/2015 Observations and Comments Seepage Areas of mineral buildup were noted, and the tunnel was well aligned with no sign of instability or distress. The usual areas of typical seeps were dry as a result of the drought conditions and low reservoir water level. A new seep from the collapsed 12?inch drain pipe that was discussed in the Dam section of this report was observed (Photo 9). This seep was estimated to be approximately 1.0 gpm. 1 reviewed the photographs taken during the Water Agency?s inspection of the outlet?s inlet trashrack structure performed on November 4, 2014. The concrete comprising the intake structure appeared to be in satisfactory to good condition. The steel trashrack and W-sections appeared to be in serviceable to satisfactory condition (Photo 11). The concrete anchors were the main areas of concern, having heavy damage due to corrosion (Photo The trashrack needs to be repaired by December 31, 2020, and if the repair is an in-kind replacement, it will be considered routine maintenance and will not require an application fee. A DVD with the photographs provided by the owner are filed in the Division?s report files. The face and right groin were dry. The toe relief drains 1-9 located were either dry, or slowly dripping. The left abutment/groin has longstanding seepage conditions and horizontal drains were installed when the dam was constructed and supplemental drains were installed in 1989 and 1984 in order to collect and combine the seepage for measurement The left groin was walked and the horizontal drains were essentially dry, due to the low reservoir water level. The Parshall ftume located at the toe of the dam that measures the combined flow from the relief and horizontal drains was dry. There are two 10~inch underdrain pipes that daylight at the end of the spillway, and these drains were dry. The instrumentation at this dam consists of 35 embankment survey monuments, 60 spillway survey monuments, t3 outlet tunnel survey monuments, 82 open well and hydraulic piezometers, 34 horizontal drains, and 10 reiief wells. The latest instrumentation submittal was dated June 31, 2014 and covered the period of December 2004 through December 2013. The beginning reporting period for the piezometer, seepage, and survey plots was changed from 1993 to 2004. The beginning reporting year needs to be Changed back to 1993 in order to facilitate the evaluation of long term trends. Piezometers and Open Wells open well and hydraulic piezometers were reported and the data was assembled into the following ten groups: upstream channel foundation, channel foundation, right abutment and bench area foundation, upper left abutment foundation, lower left abutment foundation, channel area foundation/embankment contact, upstream sheli zones, central imperious core zone, outlet conduit beneath core zone, and the drain and shell zone. Piezometric pore pressure plots covering the period of December 2004 through December 2013 were provided and the data continues to follow the trends during this 10 year reporting period. Beginning in March 2013 through December 2013, the reservoir dropped appreciably from El. 748 to El. 858. The piezometers behavior appropriately followed the dropping water level, and the majority of the piezometers respond to the reservoir's water elevation. No rising or concerning trends were noted within the 10 groups of piezometric data. Relief wells were installed at the toe area in 1970 to relieve the higher than expected hydrostatic pressures. Open Well Piezometers 108-111 were also installed in the toe and left abutment to monitor the pore pressure and the pore pressures as reported by these piezometers continue to be normal. Open Well Piezometers 109A and 110A continue to have artesian (rev.10/09) Sheet 3 of 11 INSPECTION OE DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn San Antonio Dam No. 1008-2 Date of Inspection 05/05/2015 Observations and Comments conditions excess pressure above the ground surface), but their conditions have not changed and continue to remain within historical norms. The left abutment drains were flushed in late?2011 and lower left abutment Open wells 106A, 1068, and 1060 showed drops in water levels of up to 15 feet, indicating the effectiveness of the drains was reduced before the flushing. The water levels in these three open wells have remained stable and correspond to fluctuations in the reservoir water elevation. The report identified several hydraulic piezometers that appear to be malfunctioning, and some of these hydraulic piezometers may be at the end of their useful life. in particular central impervious core Piezometers 15 and 19 were identified in the last inSpection report as having uncharacteristic behavior. Central impervious core Piezometer 15 had significant drops in head since mid-2011. Piezometer 19 had abnormal oscillatory behavior between 2011 to mid-2012, and then returned back to normal and long standing behavior of responding to the reservoir water level. Both piezometers appear to be malfunctioning. The maximum piezometer levels in the embankment'section were below the assumed phreatic surface established in 1970 stability analysis (Bechtel, 1970). An April 21, 2004 DSOD Memorandum of Design Review by Shawn Jones identified four critical piezometers to monitor. Piezometer No. 1048, 1058, and 18 in the shell and drain should remain dry and Piezometer No. 24 located in the embankment should maintain a pore pressure less than 670 feet. The three shell/drain piezometers have remained dry and Piezometer No. 24 has maintained a pore pressure near 660 feet throughout the reporting period. The dry piezometers indicate that the zone of pervious gravel material of the core is providing adequate drainage. The submittal reported data on 82 piezometers and it is recommended to simplify the report by focusing on specific piezometers judged most critical to the monitoring of San Antonio Dam. Also, piezometers that have malfunctioned should be properly abandoned or replaced, if necessary. Although it is recommended to simplify the report, the Agency should continue to internally review and evaluate all active instrumentation and data. The Agency must submit any proposed changes to the instrumentation network or submittals to DSOD for review and approval, prior to proceeding. Left Abutment Horizontal Drains There are 34 horizontal drains in the left abutment and 10 of these drains are not routinely monitored, as they are dry. The left abutment seepage responds to the reservoir water elevation and the flows had a moderate spike after the 2003 earthquake event and then another rise in 2006. The flows then had a gradual decrease since 2006 to below pre- 2003 levels and then started a gradual rise in 2011. The peak flow in 2013 was approximately 22 gpm, and this seepage dropped to approximately 1 by the end of December 2013. The November 2011 flushing of the left abutment drains resulted in increased flows and dropped the water level in three left abutment open wells. The effectiveness of this flushing will become more apparent with larger hydrostatic reservoir head and long term data. Relief Wells The total measured flow from the relief wells has historically been near 2 or less since 1993. The total peak relief well flow in 2013 was 3.4 gpm, and steadily dropped to zero as the reservoir water elevation dropped appreciably. Parshall Toe Flume This flume was installed in 2000 to measure the horizontal drains, relief wells, and toe seepage. The peak flow in 2001 was approximately 100 gpm. The total peak flow at the flume in 2013 was 45 and dropped to approximately 5 by the end of 2013. Sheet 4 of 11 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam San Antonio Dam No. 10082 Date of Inspection 05/05/2015 Observations and Comments Embankment Monuments There are a total of 35 embankment survey monuments and 21 are located along the crest and embankment. The last survey was performed in January 2014. Overall, both the horizontal and vertical displacements are small and no unusual movements or concerning trends are indicated by the survey data. The largest horizontal and verticai movements between the 2013 and 2014 surveys was approximately which is within the error tolerance of the survey. Outlet Tunnel Disptacements The outlet tunnel survey frequency has been established at five? year intervals since 2002 and after significant seismic events. The last survey for the outlet tunnel was performed in March 2012 and the next survey is scheduled for 2017. The displacement since 1993 has been essentially flat and no concerning trends or unusual movements are indicated by the data. ?piilway Monuments The vertical diSplacement of the spillway slab is grouped into Upper, Middle, and Lower survey stations and is subdivided into left, center, and right sides of the spillway. There was a period of ?questionable survey methods? and data between 2000 and 2005 was omitted. The data showed unexpected movements from year to year; however, the overall maximum movement since 1993 has been 0.1 feet (1.2 ?inches). 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SQ "Mag; 2 The: 3111111111311 1111111038111 1532111111111 SET-dim. and $111.1 "The e?im?ce shame! {Tuck-e1: Taxi-1: Temai'n jiTT sewiseabie 1111.111- Lang Ttandmg surface crackmg 1.11 1117115111 11111391? 111211111111 81:; channel 5 They are aparated 11111111111411 (1112?: 111111 year T11 ?The Saimas 1, 1111.11 IT Twas-1111113111111 T1 (33-: Reundtreewa P1111193 111111.112 Haw-? Data QC 3? 111111. 0111111111.- 512111211111. 1112111? 1.111.111. 1-2111 (51111-101191 Sheet: 1 0f" 7'3 INSPECTION DAM AND RESERVOIR IN GER-7 STATUS Name of Dam San Antonio Dam No. 1008?2 Date of inspection 3/3/2014 Observations and Comments Seepage Instr. Both valves were fuliy operated in presence on 4/10/2012. I also inspected the outlet tunnel on this date and found it to be in good condition. The interior of the tunnel was clean and mostly dry, with only minor seepage and mineral buildup along the center of the floor, as noted in previous reports. The San Antonio Dam inlet structure was inspected by MCWRA in the fall of 2013 when it was approximately 1/3 exposed. The purpose of the inspection was to report the overall condition of the structure, trash racks, anc_ gate. The concrete structure was found to be in satisfactory condition, and the metal trash racks were securely anchored to the structure. The original coating has flaked and chipped off in many pieces, and some corrosion was visible on the exposed portion of embedded concrete anchor boits and nuts. Th- gate is structurally sound, with moderate corrosion. conclusion is that the trash racks are presently stable and not in immediate danger of failure. However, they are not in a condition to perform well over the long- term due to loss of coating and corrosion. The owner needs to submit a plan and scheduie for the repair of the inlet structure. The face and right groin of the dam were dry. Toe relief drains #1-10, located along the toe, were dry or trickling. The damp spot between drains 1 2 was not observed this year. We walked the left groin and found the horizontal drains to be trickling clear water. A Parshall flume at the toe of the dam measures combined flow from the relief wells and horizontal drains. The flume reac?, or less than 5 gpm. The two 10?inch underdrains at the end of the spillway were dry. These conditions are very unusual, but not alarming, given the extreme dry conditions and the very low reservoir level. instrumentation at this dam consists of 35 embankment survey monuments, 60 spillway survey monuments, 13 outiet tunnel survey monuments, one seepage weir, 82 open well and hydraulic piezometers, 34 horizontal drains, and 10 relief wells. The latest instrumentation submittai was dated August 8, 2013 and included data through December 2012. Piezometers Piezometers are grouped by piezometer tip location as follows: upstream channel foundation, channel foundation, right abutment and bench area foundation, upper left abutment foundation, lower left abutment foundation, channel foundation and embankment contact, upstream sheli zone, central impervious core zone, outlet conduit beneath core, and drain and shell zone. Plots were provided covering the period January 2003 to December 2012. Data continues to foliow historic trends and maximum piezometric leveis within the impervious core and embankment zones remain below the phreatic surface assumed for the stability analysis. Most piezometers continue to respond as expected to reservoir elevation, with the following exceptions: (1) pore pressure at right abutment Piezometer No. 9 dipped inexplicably in October 2011 before returning to normal; (2) readings at upper left abutment Piezometer Nos. 101A and 102A dropped by ~10 feet at the end of 2011; (3) readings at lower left abutment Piezometer Nos. 106A and 106B dropped by ~12 feet at the end of 201 1; (4) readings at central impervious core zone Piezometer No. 15 showed a rapid head drop of more than 90 feet in the period between June 2011 and December 2012, and (5) central impervious core zone Piezometer No. 19 has been behaving erraticaily since April 2011. The brief dip in Piezometer No. 9 may be attributed to an error in reading and appears to have no Sheet 2 of 7 INSPECTION 7 DAM AND RESERVOIR IN STATUS Name of Darn San Antonio Dam No. 1008-2 Date of Inspection 3/3/2014 Observations and Comments lasting effects. Also, the left abutment drains were flushed in late 2011 and the pressure drops seen at Piezometer Nos. 101A, 102A, 106A, and 1068 in the left abutment are likely related. However, the abnormal behavior noted at Piezometer Nos. 15 and 19 warrants careful monitoring and further analysis in the next instrumentation submittal, as these piezometers may be malfunctioning. An April 21, 2004 DSOD Memorandum of Design Review by Shawn Jones identified four critical piezometers to monitor at this dam. Piezometer Nos. 1048, 1058, and 18 in the sheli and drain zone should always remain dry and Piezometer No. 24 in the embankment should maintain a pore pressure less than 670 feet. During this reporting period, the three shell/drain piezometers remained dry, indicating the gravel material of the core is providing adequate drainage. The embankment piezometer remained below 666 feet. As discussed during the maintenance inspection, the Agency should continue to internally review all active instrumentation data, but we recommend making the annual submittals more manageable by assessing which instruments are most critical to the monitoring of the embankment, and properly abandoning or replacing those piezometers which have malfunctioned, if necessary. All changes to the instrumentation network or submittal report require our prior written approval. Left Abutment Horizontal Drains There are 34 horizontal drains in the left abutment, of which 10 are not routinely monitored, as they are dry. In 2012, combined left abutment drain flow peaked at ~46 in February. Left abutment seepage continues to respond to the reservoir elevation. A moderate rise in seepage was noted in 2011 and continued through 2012, but this was likely due to the high reservoir elevation which persisted both of those years. A similar rise in seepage occurred in 2006, when the reservoir last spilled. Relief Wells There are 10 relief wells located along the toe of the dam. In 2012, combined relief well fiow peaked at ~6 in June. The relief walls have historically fiowed ~5 or less since 1993. Flows peaked after the 2003 earthquake event and then steadily decreased back to historical levels. Parshall Toe Flume This flume was installed in 2000 to measure flow from the horizontal drains, relief wells, and toe seepage. In 2012, fiow through the Parshall flume peaked at ~86 at the beginning of the year. This flow is nearly twice the combined fiow of the relief wells and left abutment drains, indicating that toe seepage during the same period peaked at ~40 gpm. These lower flows are not surprising, given persistent dry conditions at the dam. Embankment Monuments There are a total of 35 embankment survey monuments, 21 of which are located along the crest and embankment. The last survey was performed in January 2013, and shows minimal movement and general behavior consistent with past surveys. I noted no concerning trends in the data. The greatest horizontai and vertical movements between the 2012 and 2013 surveys wer- anc_, respectively. This is within the tolerance of the survey, as noted in previous reports. Outlet Tunnel Monuments The outlet tunnel survey frequency has been established at 5-year intervals since 2002. The last survey for the outlet tunnel was performed in March 2012, and the next survey is scheduled for 2017. Spillwav Monuments The vertical displacement of the spillway slab is grouped into upper, middle, and lower survey stations, and is further subdivided into left, center, and right sides of the spillway. Sheet 3 of 7 INSPECTION DAM AND RESERVOIR IN CERF STATUS Name of Dam San Antonio Dam No. 1008-2 Date of Inspection 3/3/2014 Observations and Comments Movements seem to vary quite randomly from year to year, but the maximum movement at any point since 1993 remains less tha_ which is acceptable. Movements appear to be affected by reservoir level and the resultant seepage under the spillway panels. Survey data from the most recent monument survey on 1/24/2013 is not shown on time plots; this error needs to be corrected on the next annual submittal. The data indicates that the dam continues to perform adequately. The current instrumentation network and monitoring frequencies are satisfactory, and no additional instrumentation is deemed necessary at this time. Sheet 4 of 7 . .5393.me Ems @3333 paw ma gig. $3 ?Qmm?m 6 if. . . ?a gramJmm/ . .. 13. a . up. 4117/ . Msfx?/?wmxm[111.4 121.? I . ?o?sw?mm? ?mam a. amg 4.7M .. . .1. 110. . an f/Mmm1.1.. 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E0000 00E0r30r0000 ?1330000000 0033 0 E0030 080-000 000. '00 300003! 03.00- 0000 i03000i't00t E00 03030030. 0000;? .0500 1000E00 in .0 0000300 3'0E0i00000 E0000 thai'ia 000000.00 waive-000 0 003330000030? 00300, Q0002 T00 0'0 03": 00000003 The 000330030 0'00- 0003000'0003 330000 W030 053000003100 EMA-300000000 00013200000A0 100. .. 000% i31tii<30t00 00 0053300 .030 003000 3000103 gihmuqmui ?30- 00073 033 3030000 E20300 E00: T3 30.500000 by . . V0003- . 13-00300 3.0000"? N?mm {30:0 03? i00000ii00 .. for Data-0.: 3303303: GEEQZEEQE 3' 3031A 03333010030200.1000}. 9-3000: INSPECTION Oi DAM AND RESERVQIR IN STATUS Name of Dam San Antonio Dam No. 1008-2 Date of Inspection 04/04/2013 Observations and Comments Seepage Instr. Salinas River. During this inspection, 64 was being released into the river. DSOD last witnessed the operation of the two valves during the last inspection of April 10, 2012. The outlet tunnel was inspected and was found to be well lit, weil ventilated and in good condition. Areas of minor seepage and mineral buildup were noted and the tunnel was well aligned with no sign of instability or distress. The face and right groin were dry. The toe relief drains 1-9 located on the toe had various flow conditions from drips to live flows. A minor moist spot located between Drain 1 and Drain 2 was observed (Photo 3) and is being monitored by the Water Agency. The left abutment/groin has longstanding seepage conditions and horizontal drains were installed when the dam was constructed and supplemental drains were installed in 1969 and 1984 in order to collect and combine the seepage for measurement The left groin was walked and the horizontal drains were flowing clear. A flow of 47 was measured at the Parshall flume located at the toe of the darn that measures the combined flow from the relief and horizontal drains. There are two 10-inch underdrain pipes that daylight at the end of the spillway. During this inspection, the right underdrain was flowing approximately 4-5 and the left drain was flowing approximately 1 gpm. The seepage measured at the Parshall flume and spillway underdrains during this inspection is considered normal and within historical norms. The instrumentation at this dam consists of 35 embankment survey monuments, 60 spiilway survey monuments, 13 outlet tunnel survey monuments, 82 open well and hydraulic piezometers, 34 horizontal drains, and 10 relief wells. The latest instrumentation submittal was dated June 11, 2012 and covered the period of December 1993 through December 2011. Piezometers Eighty-two open well and hydraulic piezometers were reported and the data was assembled into the following ten groups: upstream channel foundation, channel foundation, right abutment and bench area foundation, upper left abutment foundation, lower left abutment foundation, channel area foundation/embankment contact, upstream shell zones, central imperious core zone, outlet conduit beneath core zone, and the drain and shell zone. Piezometric pore pressure plots covering the period of December 1993 through December 2011 were provided and the data continues to follow historic trends. The majority piezometers respond to the reservoir?s water elevation. No rising or concerning trends were noted within the 10 groups of piezometric data. Relief wells were installed at the toe area in 1970 to relieve the higher than expected hydrostatic pressures. Open Weil Piezometers 106-4 11 were also installed in the toe and left abutment to monitor the pore pressure and the pore pressures as reported by these piezometers continue to be normal. Open Well Piezometers 109A and 110A continue to have artesian conditions excess pressure above the ground surface), but their conditions have not changed and continue to remain within historical norms. The left abutment drains were flushed in late-2011 and the left abutment piezometers showed drops in pore pressures of up to 15 feet (Piezometer No. 1068), indicating the effectiveness of the drains was reduced before the flushing. These conditions need to be evaluated in the next instrumentation submittal. An April 21, 2004 DSOD Memorandum of Design Review by Shawn Jones indentified four critical piezometers to monitor. Piezometer No. 1048, 1058, and 18 in the shell and drain should remain dry and Piezometer No. 24 located in the embankment should maintain a pore pressure less than 670 feet. The three shell/drain piezometers have remained dry and Piezometer DWR 1261 (rev. 10/09) Sheet 2 of 7 INSPECTION OX DAM AND RESERVOIR IN STATUS Name of Dam San Antonio Dam No. 1008-2 Date of inspection 04/ 04/201 3 Observations and Comments N0. 24 has maintained a pore pressure near 660 feet throughout the reporting period. The dry piezometers indicate that the zone of pervious gravel material of the core is providing adequate drainage. The submittal reported data on 82 piezometers and it is recommended to simplify the report by focusing on specific piezometers judged most criticai to the monitoring of San Antonio Dam. Also, piezometers that have malfunctioned should be properly abandoned or replaced, if necessary. Although it is recommended to simplify the report, the Agency should continue to internally review and evaluate all active instrumentation and data. The Agency must submit any proposed changes to the instrumentation network or submittals to DSOD for review and approval, prior to proceeding. Left Abutment Horizontal Drains There are 34 horizontal drains in the left abutment and 10 of these drains are not routinely monitored, as they are dry. The left abutment seepage responds to the reservoir water elevation and the flows had a moderate spike after the 2003 earthquake event and then another rise in 2006. The flows then had a gradual decrease since 2006 to below pre- 2003 ievels and then started a gradual rise in 2011. The peak flow in 2011 was approximately 50 gpm, down from the peak of 128 in 2006. The left abutment drains flushing in late?2011 may be the cause of the rise in 2011 that coincides the drop in the left abutment piezometer readings. As discussed above, the effectiveness of drain flushing needs to be assessed in the next instrumentation submittal. Relief Weils The total measured flow from the relief wells has historically been near 2 or less since 1993. The flows peaked to 28 after the 2003 earthquake event and then steadily decreased back down to historicai flow of 2 gpm. Parshall Toe Flume This flume was installed in 2000 to measure the horizontal drains, relief wells, and toe seepage. The peak flow in 2001 was approximately 100 gpm. As with the left abutment drains, the flow has steadily decreased since the peak of 248 in 2006. There is a discrepancy between the total flow as measured by the flume as compared with the left abutment drains and the relief wells of approximately 55 percent. This indicates the left abutment drains and the toe relief wells are not capturing all seepage, and that artesian flow is bypassing the drains/wells. Embankment Monuments -- There are a total of 35 embankment survey monuments and 21 are located along the crest and embankment. The last survey was performed in February 2012. Overall, both the horizontal and vertical displacements are small and no unusual movements or concerning trends are indicated by the survey data. The largest horizontal and vertical movements between the 2011 and 2012 surveys was approximately which is within the error tolerance of the survey. Outlet Tunnel Dispiacements The outlet tunnel survey frequency has been established at five- year intervals since 2002 and after significant seismic events. The last survey for the outlet tunnel was performed in March 2012 and the next survey is scheduled for 2017. The displacement since 1993 has been essentially flat and no concerning trends or unusual movements are indicated by the data. SpillWav Monuments The vertical displacement of the spillway slab is grouped into Upper, Middle, and Lower survey stations and is subdivided into left, center, and right sides of the spillway. There was a period of ?questionable survey methods" and data between 2000 and 2005 was omitted. The data showed unexpected movements from year to hear; however, the overall maximum movement since 1993 has been 0.06 fee?). The movements appear to be infiuenced by Sheet 3 of 7 9. mg .9..sz mm. amm?mmw m?gm zmamagg Ea. .zm. . Emmym mm?? 2.. mamm?wm?w .3. . .Am??m7. .Hm. x. . .. $36 4. 43m. 3% I. .23?.4me m. b, ?"5;me magmgm? mmovm. m5. Ema Emma. 53am? on m. ?nm? my WE @W?wcm zm?a mama mm: Riga. mm; 2.0.. mam ma??m?magmas. a? ?93% m. a mm mm RES-mwm Name 01? Dam San grif?n-13? Dam Na. "1.113983% ma?a of?inspea?on 04/045231 3 x4? .. - (f Iu'n' . u? - .- Pit-?mtg. The: rec; ears-w mini-s tea-the i'eftouifga? Gf'ilhai umdardrain Eacaie? at?fhe- ENE-1.261 10m). .aheet pf' 72'