STATE OF CALIFORNIA '9 . CALIFORNIA NATURAL RESOURCES AGENCY Eva ii DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam NaCimien?to Dam No. 1008 County San LUIS Obispo Type of Dam Earth Type of Spillway Concrete Weir and Channel Water is 30.15 feet below spillway crest and 67.45 feet below dam crest. Water Elevation: 757.55 ft Weather Conditions Partly Sunny, Mild, and Calm Contacts Made Chris Moss, Nick Becker, Richard Nason, Pat Ledo, and Paul Guzman with MCWRA. Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken 1. Before using the Obermeyer gates to store water, the Owner needs to address the action items listed in the Division?s June 7, 2013 letter. 2. The corrosion on the Obermeyer steel gate panels and bolts needs to be removed and touched up with paint. . 3. The torque settings of the Obermeyer gate panel bolts need to be checked annually after the gates are used to impound water, or every five years when they do not impound water. 4. The upstream and low-level outlet valves need to be exercised during the next inspection. 5. Complete repairs to the low?level outlet Valve 6. Include short-term and long-term plots and an engineering evaluation in the instrumentation submittals. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments [Zia?m The crest ofthe dam is the two?lane Nacimiento Lake Drive and was uniform. well aligned, and well maintained. The aSphalt paved crest was in satisfactory condition having the typical cracking associated with asphalt pavement. The visible portion of the rip?rap covered upstream slope was uniform and in good condition. The rip-rap protected slope as viewed from the crest, the upper and lower benches, and the toe was also in good condition with no sign of instability or distress. The visible portions of the upstream groins and the groins and toe areas were fully inspected. The abutments appeared stable and the groins and toe area were normal. Vegetation control was excellent and no concerning rodent activity was observed. Spillway The approach, control section, and exit were satisfactory clear of concerning debris. The spillway concrete structure and Obermeyer gates were Inspected. The concrete comprising the weir, invert and channel walls were In good condition. Although minor surficial cracking on the concrete walls and invert was noted throughout the spillway structure, the panel joints were well?aligned and no distress or instability was observed. The spillway box culverts to the high?level spillway gates were not inspected and the high?level gates were not cycled during this inspection. of the spillway, substantial channel erosion along the left bank occurred during a 2011 flood event (Photo 4). Although this does not appear to pose a dam safety concern at this time, the Owner has plans to armor this area. A thorough inspection of the Obermeyer gates and their control system was conducted. This Andrew Mangney 13? 5M9 Inspected by Bill Vogler UV Photos taken? Yes No Date of Inspection 04for Owner/Field Book/File Date of Report 07/23/2013 ?15, I DWR 1281 (Rev. 10109) Sheet 1 of 5 INSPECTION OI- DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 04/05/2013 Observations and Comments Outlet Seepage Instr. inspection was led by Andrew Mangney of DSOD, which is documented in a separate memorandum. The gates were fully raised and lowered during this inspection. It took approximately 20 minutes to raise each gate and it took over an hour to lower the gates. The operation went smoothly and no problems were encountered. The visible portions of the bladders and gate panels appeared in good condition. The restraining straps appeared in good condition and were well attached to the spillway structure. We inspected the upstream side of the gates after they were lowered and the steel panels appeared in good condition with no sign off stress or unusual conditions. Minor corrosion was noted at a few locations on the panels and at some of the bolts connecting the gate panels together (Photo 5). The corrosion should be removed and repainted. All fasteners appeared adequately secured, and according to Mr. Becker, most of the bolts had to be tightened after the gates stored water during the spring of 201 1. MCWRA plans to check the bolt torque after each time the gates impound water. This plan is acceptable; however, the bolts should be checked every 5?years if they have not been operated to impound water. Nick Becker of MCWRA described the operation of the equipment in the control building which included the Program Logic Control Panel, compressors, air pressure control cabinet and air lines, and the back-up diesel generator. All the associated equipment appeared to be in excellent condition and well maintained. A more thorough inspection of the Obermeyer gates report and findings is given in Mr. Mangney?s April 5, 2013 Memorandum of Field Inspection. As the result of this inspection, a June 7, 2013 letter was sent to the Owner with nine action items to be acted upon. The low-level outlet consists of a 54-inch steel pipe encased in reinforced concrete and is controlled by three upstream 42?inch butterfly valves and six 24?inch inline gate valves. Mr. Moss presented me the operational history of the upstream butterfly valves during the January 2012 through March 2013 time period. The South Valve was re-built and fully cycled on March 26, 2013. The Center and North valves were removed and were being rebuilt, having plans to be back in operation by the end of April 2013. Work crews were present in the hydroelectric plant, and for safety reasons, none ofthe valves were operated during this inspection. Valve #2 had been removed for so repairs could be made to the damaged elbow pipe that was connected immediately of the valve. Arrangements need to be made to witness the cycling of both the upstream and outlet valves during the next inspection. The face, groins, and toe of the dam were dry with no evidence of seepage. There are two surface water drains for the upper berm and right spillway wall and these drains were not inspected. The instrumentation at this dam consists of 15 survey monuments in which twelve monuments are located on the crest and the remaining three are located at the spillway. The latest instrumentation submittal was dated April 27, 2012 and covered the period of December 1993 through January 2012. The survey data was reviewed in the previous inspection report and no concerning trends or anomalous behavior was indicated by the data. The data was presented in tabular format only and a letter was sent to the Owner requesting that short-term plots (5 years) and long-term plots (life of the dam) be included in future submittals. An engineering evaluation should also be included which discusses the results as it relates to the operation and safety of the dam. The instrumentation data indicated that this dam is performing adequately. Therefore, the existing DWR1261(rev.10109) Sheet 2 of 5 INSPECTION Or- DAM AND RESERVOIR IN STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 04/05/2013 Observations and Comments instrumentation and their monitoring frequency are judged sufficient at this time. Photo 1. A View of the slope of the dam as seen from near the left abutment. Sheet 3 of INSPECTION O. DAM AND RESERVOIR IN STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 04/05/2013 .Ina? . I - I Photo 3. Looking upstream inside the spillway channel towards the closed Obermeyer gates. Sheet 4 of INSPECTION O. DAM AND RESERVOIR IN STATUS Name of Darn NaCimientO Darn No. 1008 Date of Inspection 04/05/2013 Photo 4. The red arrow points to the area of erosion that occurred during a 2011 flood event. Photo 5. An example of minor corrosion. that is occurring on some of the Obermeyer gate panels. Sheet 5 of STATE OF CALIFORNIA .0 CALIFORNIA NATURAL RESOURCES AGENCY ?1 :9 DEPARTMENT OF WATER RESOURCES - DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Nacimiento Dam No. 1008 County San Luis Obispo Type of Darn Earth Type of Spillway Concrete Weir and Chute Water is 97.7 feet below spillway crest and 122.7 feet below dam crest. Weather Conditions Overcast, 60 degrees F. Contacts Made Chris Moss, Richard Nason, and Pat Ledo w/ Monterey County Water Resources Agency. Reason for Inspection Annual Maintenance Inspection. Important Observations, Recommendations or Actions Taken The corrosion on the steel Obermeyer gate panels and bolts appeared to have been addressed. The repairs to gate valve #2 have been completed. All upstream butterfly valves and gate valves were fully cycled during the inspection, except for gate valve which was out for service. The following items require the owner's attention: 1. Before using the Obermeyer gates to store water, the owner needs to address the action items listed in the Division?s June 7, 2013 letter. 2. The current instrumentation submittal is overdue. Include short-term and long-term plots and an engineering evaluation in future instrumentation submittals. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments Da_m I walked the crest, groins and toe of the dam, and inspected the face and the majority of the upstream face. The paved crest road remains level and in good condition, with typical asphalt cracking. The embankment was in satisfactory condition and showed no signs of instability or distress. The abutments appeared stable and rip-rap protection on the upstream and slopes remained in good condition. Vegetation control was excellent, and there were no signs of rodent activity. Spillway The spillway approach, control section and exit channel were clear and unobstructed. All concrete surfaces remain in good condition with only minor surface cracking visible on the walls and invert. Spillway panel joints are well-aligned and did not suggest any distress or instability. inspected the spillway box culverts to the low level spillway gates and found all surfaces to be in good condition. A detailed inspection of the Obermeyer gates and their control system was conducted during the previous maintenance inspection on 4/5/2013, and therefore I did a cursory inspection on this date. The corrosion noted on the steel Obermeyer gate panels and bolts appeared to have been addressed since the previous inepection. Before using the ObermBYer gates to store water. the owner needs to address the action items '21?14 listed in the Division's June 7, 2013 letter ACK 6 F4- UV Inspected by A. C. Roundtree 6. Photos taken? Yes NO Date of Inspection 3/3/2014 var cc for Owner/Book Date of Report 3/27/2014 DWR 1261 (Rev. 10/09) Sheet 1 of 5 INSPECTION . DAM AND RESERVOIR IN .ED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 3/3/2014 Observations and Comments Outlet Seepage The low level outlet is a 54-inch steel pipe encased in reinforced concrete, and equipped with three upstream 42-inch butterfly valves and six 24?inch inline gate valves. All upstream butterfly valves and gate valves were fully cycled during the inspection, except for gate valve which was out for service. This gate valve was last cycled in presence on 4/10/2012. There was no evidence of seepage on the face, groins, or toe of the dam, and the surface water drains for the upper berm and right spillway wall were dry. These conditions were not surprising, given the extreme dry conditions this year, and the very low reservoir level. Instrumentation at the dam consists of twelve survey monuments on the crest of the dam and three survey monuments at the spillway. The latest instrumentation submittal was dated April 27, 2012 and included data through January 2012. The data was reviewed in the inspection report dated Bit/2012, and no concerning trends or anomalous behavior was indicated by the data. A current instrumentation submittal is overdue. As noted in the previous inspection, short-term and long-term . plots and an engineering evaluation need to be included in future submittals. DWR1261 (rev. 10,109) Sheet 2 of 5 INSPECTION t. DAM AND RESERVOIR IN .ED STATUS Name of Dam Nacimiento Darn No. 1008 Date of Inspection 1. face of dam viewed from left abutment. 2. Upstream face ofdam viewed from piliway approach. DWR1261(rev.10i09) . Sheet 3 of INSPECTION - DAM AND RESERVOIR IN CERT STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inapection 3/3/2014 n. 3. Spillway control structure viewed from upstream chnanel. .gvf71:54Spillway control structure ?iewed from chute. DWR1251 (rev. 10mg) Sheet 4 of INSPECTION DAM AND RESERVOIR IN IED STATUS Name of Dam Nacimiento Dam No. Date of Inspection ng gate valves at the toe were cycled. (valve #6 was removed for service) IA Ur; - 5. The five operatl It L. 4. .c 6. 24?inch gate valve full open. DWR 1261 (rev. 10109) 1008 3/3/2014 Sheet ?1 STATE OF CALIFORNIA gm, CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS he INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Nacimiento Dam No. 1008 County San LUIS ObiSpO Type of Dam Earth Type of Spillway Concrete Weir and Channel Water is 52.8 feet below spillway crest and 90.1 feet below dam crest. Water Elevation: 757.55 ft Weather Conditions Partly Sunny, Mild, and Calm Contacts Made Chris Moss, Russell Kelson, and Pat Ledo with MCWRA. Reason for Inspectioh Periodic Maintenance Inspection important Observations. Recommendations or Actions Taken 1. Before using the Obermeyer gates to store water, the Owner needs to address the action items listed in the Division's June 7, 2013 letter. As of this inepection, four of the nine action items have been adequately addressed. The remaining items are scheduled to be completed by October 1, 2015. 2. The corrosion on the Obermeyer steel gate panels and bolts needs to be removed and touched up with paint. 3. The Obermeyer gate delaminated seams need to be repaired. 4. The torque settings of the Obermeyer gate panel bolts need to be checked annually after the gates are used to impound water, or every five years when they do not impound water. The torque settings need to be checked in the spring of 2016 if no water has been impounded by that date. Complete repairs to the low-level outlet Valve A cursory review Ofthe July 2014 FERC Part 12D Safety Inspection Report found that no significant deficiencies were identified. The studies and issues the Division is already aware of are mentioned in the report. 7. The January 13, 2012 inspection report of the intake structure and outlet pipe by DRS Marine Inc. was reviewed and no deficiencies were noted. 8. As requested, short?term plots and long-term plots, and an engineering evaluation were included in the instrumentation report. .oww Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Da_m The crest of the dam is the two-lane Nacimiento Lake Drive and was uniform, well aligned, and well maintained. The asphalt paved crest was in satisfactory condition having the typical cracking associated with asphalt pavement. I observed a small depression in the center of the road, near Sta. 13+50, which may indicate a loss of the material underneath the pavement. Although this does not appear to be an immediate safety concern, this area should be monitored for further Changes or conditions. The reservoir was low and was able to inspect the upstream slope from the water?s edge. The riprap was intact, and the upstream slope appeared uniform and stable. The rip?rap protected slope was inspected from the crest, the upper and lower benches, and the toe. The slope appeared in overall good condition, with no sign of unstable or concerning conditions. The visible portions of the upstream groins and the grains and toe areas were inspected. The abutments appeared stable and the groins and toe area appeared normal. Vegetation control was excellent and no concerning rodent activity was observed. ID at; Inspected by Bill Vogler A Photos taken? Yes No Date of Inspection 05/05/2015 cc for Owner/Field Book/File Date of Report 06/01/2015 ?1??le w? DWR 1261 (Rev. 10109) Sheet 1 of 5 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Nacimiento Dam No. 1008 Date of Inspection 05/05/2015 Observations and Comments Spillway Outlet The approach, control section, and exit were satisfactorily clear of concerning debris. The spillway concrete structure and Obermeyer gates were inspected. The concrete comprising the weir, invert and channel walls were in overall good condition. Although minor spalls and surficial cracking on the concrete walls and invert were noted throughout the spillway structure, the panel joints were well-aligned and no distress or instability was observed. The spillway box culverts appeared in satisfactory condition, and the high-level gates were not cycled during this inspection. The high level gates were last cycled by the owner on April 9, 2015. of the spillway, substantial channel erosion along the left bank occurred during a 2011 flood event (Photo 4). I did not observe any apparent changes, or worsening conditions, as compared to my April 5, 2013 inspection. Although this does not appear to pose a dam safety concern at this time, the Owner has plans to armor this area. The Obermeyer gates were fully raised and lowered during this inspection. The operation went smoothly and no problems were encountered. I performed a cursory inspection of the visible portions of the gates. All fasteners appeared adequately secured. MCWRA plans to check the bolt torque after each time the gates impound water and every 5-yearss if they have not been operated to impound water. The gates last stored water in the spring of 2011, and the bolts will need to be checked in the spring of 2016 if the gates have not stored water by that date. The inflated bladders appeared to be in good condition, and Mr. Moss informed me that the Obermeyer Hydro Inc. would repair the seams that were delaminated (Photo 3) during their scheduled visit in August 2015. I did not inspect the upstream portions of the gates during this inspection. The minor corrosion observed at a few locations on the panels and at some of the bolts connecting the gate panels together had not been removed and repainted as requested during my April 5, 2013 Inspection. According to Mr. Moss, the corrosion repair will be addressed in August 2015. All the associated Obermeyer gate equipment located in the control building, and in the airline purge box, appeared to be in excellent condition and well maintained. DSOD will allow storage against the Obermeyer gates once all the action items outlined in our June 7, 2013 letter are addressed. Ofthe nine action items, four have been satisfactorily addressed, and Mr. Moss reported that all remaining items will be addressed by October 1, 2015. The low-level outlet consists of a 54-inch steel pipe encased in reinforced concrete and is controlled by three upstream 42-inch butterfly valves and six 24?inch inline gate valves. Valve #6 has been removed and is scheduled for installation during the 2015/2016 fiscal year. None of the outlet valves were operated during this inspection. DSOD last witnessed operation of the outlet system during our March 3, 2014 inspection. The three upstream 42?inch butterfly valves were last operated on April 1, 2015, and the five operable gate valves were fully cycled on various dates in February and March of 2015. I reviewed the January 13, 2012 inspection report by DRS Marine Inc. which inspected the following areas of the outlet system (the report has been placed in the Division's correspondence file): 1. Dive inspection of the inside of the intake structure. The interior of the intake structure was in overall satisfactory condition. All three butterfly?s valve housing showed minor pockets of corrosion, but the seating gaskets were in good condition. The only item of note was the hydraulic hose to the center butterfly valve was severed. The hydraulic lines DWR1261 (rev. 10:09} Sheet 2 of 5 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 05/05/2015 Observations and Comments Seepage Other 3 U1 r?I- to all three valves were replaced. 2. Dive inspection of the outside of the intake structure. All three trashracks appeared in satisfactory condition 3. ROV inspection of the outlet pipe. The entire length of the outlet pipe was inspected with an ROV, and a video DVD was included that documented the inspection. No concerning conditions were noted during the ROV inspection, and the outlet pipe appeared to be in satisfactory condition. Small cracks were noted in the pipe liner, and most of the cracks had been previously marked with paint. I reviewed the DVD and concurred with the report. The DVD has been placed in our report files. The face, groins, and toe of the dam were dry with no evidence of seepage. There are two surface water drains for the upper berm and right spillway wall, and these drains were dry. I performed a cursory review of the July 2014 FERC Part 12D Safety Inspection Report and found no significant deficiencies were identified that DSOD is not aware of. Some of the report?s recommendations that DSOD is aware of are: 1) the left bank of the spillway plunge pool needs to be stabilized by armoring, 2) survey monuments should be installed on the upper and lower benches to monitor movement, 3) piezometers should be installed to monitor phreatic surface and pore pressures in the dam and foundation, 4) conduct investigations for an updated seismic stability evaluation. The report concluded that no observations were made that requires immediate action. The Division is aware of this planned work, and all other items are considered routine maintenance and monitoring. The Part 12D report has been filed in the Divisions? report file The instrumentation at this dam consists of 15 survey monuments in which twelve monuments are located on the crest and the remaining three are located at the spillway. The latest instrumentation report dated May 29, 2014 covered the period of January 2013 through March 2014. As requested, short-term plots (5 years), long?term plots (1993-present), and an engineering evaluation was included in the instrumentation report. The results of the 2000 through 2005 surveys were considered unreliable due to the accuracy and consistency of the data. This issue was resolved by using the survey methods used in the pre- 2000 surveys beginning in 2006 and continued to the present. The maximum settlement between the January 26, 2012 and January 9, 2013 surveys was 0.013?ft (0.16?inch) and the maximum horizontal displacement was 0.05?ft (OB-inches) in both the upstream and direction. The magnitude of these movements in both the vertical and horizontal directions are considered insignificant and within the degree of accuracy of the survey. For the long-term evaluation of survey, fifteen surveys were used over the period of 1993 through 2013. The maximum settlement occurred at the maximum section, having a value of 0.097-ft (1 inches). The maximum overall horizontal displacement ranged from 0.05-ft (OE-inches) upstream and 0.01?ft (1 .2?inches) These diSplacements are considered small, and the data appears to indicate that there are no concerning movements or trends developing at the dam. The instrumentation data indicated that this dam is performing adequately. Therefore, the existing instrumentation and their monitoring frequency are judged sufficient at this time. Sheet 3 of 5 Name ofDam Nacimiento Dam No. 1008 INSPECTION OF DAM AND RESERVOIR IN STATUS Date of Inspection 05/05/2015 Photo 1. A View of the upstream slope of the dam as seen from near the right abutment. Photo 2. A view of the raised Obermeyer gates. DWR1261(rev.10l09) Sheet 4 of 5 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam NaCimiento Dam No. 1008 Date of Inspection 05/05/2015 Photo 3. The red arrow points a location where the seam to the bladder of the Obermeyer gate is delaminating. Photo 4. A View of the channel erosion along the left bank and of the spillway's plunge pool that occurred during a 2011 flood event. DWR 1261 (rev. 10mg) Sheet 5 of 5 STATE OF CALIFORNIA '1 1 CALIFORNIA NATURAL RESOURCES AGENCY . DIVISION OF SAFETY OF DAMS DEPARTMENT OF WATER RESOURCES INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Nacimiento Darn No. 1008 County San Luis Obispo Type of Dam Earth Type of Spillway Concrete Weir and Channel Water is 45.15 feet below spillway crest and 82.4 feet below darn crest. Water Elevation: 742.6 ft Weather Conditions Sunny, Clear Skies, and Warm. Contacts Made Chris Moss, Russell Kelso, Brent Bartlett, and Pat Ledo with IVICWRA. Reason for Inspection Periodic Maintenance Inspection Important Observations, Recommendations or Actions Taken The following items require the Owner?s attention: 1. The Owner has not addressed all ofthe action items listed in the Division?s June 7, 2013 letter. However, this is acceptable since DSOD will not allow storage against the Obermeyer gates until all the action items are satisfactorily addressed. 2. The corrosion on the Obermeyer steel gate panels and bolts has not been removed and touched up with paint, and the delaminated seams have not been repaired as requested during the previous inspection. These items will be addressed when Obermeyer makes a site visit to address the other outstanding issues. 3. The torque settings of the Obermeyer gate panel bolts need to be checked annually after the gates are used to impound water, or every five years when they do not impound water. The torque settings are scheduled to be checked at the end of May 2016 4. The installation of a multi-orifice energy dissipating gate valve to replace the damaged eccentric plug Valve #6 is scheduled during the 2016/2017 fiscal year. The Owner needs to submit the replacement proposal once it becomes available, and if we determine the work is essentially an in-kind replacement, it will be considered routine maintenance and we will not require an application. 5. The instrumentation submittal is overdue and needs to be submitted annually. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Da_m The crest of the dam, the two?lane Nacimiento Lake Drive was uniform, well aligned, and well maintained. The asphalt paved crest was in satisfactory'condition having the typical cracking associated with asphalt pavement. The small depression in the center of the road, located near Sta. 13+50, appeared unchanged as compared with the previous inspection. The reservoir was low and I inspected the upstream slope from the crest and right and left upstream groins. The riprap was intact, and the upstream slope appeared uniform and stable. The rip-rap protected slope was inspected from the crest, the upper and lower benches, and the ice. The visible portions of the upstream groins and the groins and toe areas were inspected. The abutments appeared stable and the groins and toe area appeared normal. Vegetation control was excellent and no concerning rodent activity was observed. The Nacimiento Dam FERC Part 12 Report dated July 2014 identified two areas of concern or\@ the slope that needs monitoring: a? 1. There is a bulge and low spot on the upper bench near Sta. 21+00 (Photo 86" Inspected by Bi? i, '9 i Photos taken? YES N0 Date of Inspection 05/12/2016 so for Owner/Field Book/File Date of Report 07/13/2016 I DWR1261 (Rev. 10109) Sheet 1 of 5 INSPECTION DAM AND RESERVOIR IN IED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 05/1 212018 Observations and Comments Spillway 2. Minor depressions along the slope located at the left end of the lower bench (Photo 3). Mr. Moss informed me that survey monuments are scheduled to be installed on the upper and lower benches in the fall of 2016, and a survey monument will be installed at the low spot on the upper bench near Sta. 21 +00. The minor depressions near the left end of the lower bench were subtle and and may be due to minor loss of the embankment material below the riprap. inspected both areas and i did not have any immediate concerns, and Mr. Moss told me that the Agency?s staff monitors these locations on a basis. The approach, control section, and exit were satisfactorily clear of concerning debris. The spillway concrete structure and visible portions of the Obermeyer gates were inspected. The concrete comprising the weir, invert and channel walls were in overall good condition. Although minor spalls and surficial cracking on the concrete walls and invert were noted throughout the spillway structure, the panel joints were well-aligned and no distress or instability was observed. The spillway box culverts associated with the high-level outlet appeared in satisfactory condition, and the high?level gates were not cycled during this inspection. The high level gates were last cycled by the owner on September 3, 2015. of the spillway, substantial channel erosion along the left bank occurred during a 2011 flood event. Due to the successive drought conditions and low reservoir water level, the darn has not spilled and conditions have not changed since my May 5, 2015 inspection. Although this does not appear to pose a darn safety concern at this time, the Owner has plans for a slope stability remediation for this area (possibly beginning in 2019). The Obermeyer gates were in the fully closed position and were not cycled during this inspection. They were fully cycled on April 1, 2016 and they reportedly operated without any issues. I performed a cursory impaction of the upstream visible portions of the gates and they appeared in good condition. MCWRA is required to check the bolt torque after each time the gates impound water and every 5-years if they have not been operated to impound water. The gates last stored water in the spring of 201 1, and the bolt torque settings are scheduled to be performed at the end of May 2016. The corrosion on the Obermeyer steel gate panels and bolts has not been removed and touched up with paint, and the delaminated seams have not been repaired as requested during the previous inspection. Mr. Moss informed me that the Obermeyer Hydro Inc. would repair the seams during their site visit to address the other outstanding issues. All the associated Obermeyer gate equipment located in the control building, and in the air-line purge box, appeared to be in excellent condition and well maintained. The MCWRA has not addressed all of the action items outlined in our letters dated May 6, 2016 and June 7, 2013 involving the Obermeyer gates; however this is acceptable since DSOD will not allow storage against the Obermeyer gates until all the action items are satisfactorily addressed. Mr. Moss reported that there are five outstanding items that need to be completed. The low-level outlet consists of a 54-inch steel pipe encased in reinforced concrete and is controlled by three upstream 42-inch butterfly valves and six 24-inch inline gate valves. The three upstream 42-inch butterfly valves were last cycled on May 9, 2016, and the five operable gate valves were fully cycled in April of 2016. None of the outlet valves were operated during this inspection. DSOD last witnessed operation of the outlet system during our March 3, 2014 inSpection. DSOD requires that the low?level outlet system be cycled at least annually and in our presence every three years. Arrangements need to be made to cycle the DWR 1261 (rev. 10/09) Sheet 2 of 5 DAM AND RESERVOIR IN STATUS Name of Dam Nacimiento Dam No. 1008 Date of inspection 05/12/2016 Observations and Comments Seepage upstream and outlets during the next maintenance inspection. The eccentric plug Valve #6 has been removed and replaced by a blind flange. The valve is scheduled to be replaced with a Ross Model multi-orifice energy dissipating gate valve during the 2016/2017 fiscal year. The Owner needs to submit the replacement proposal once it becomes available, and if we determine the work is essentially an in?kind replacement, it will be considered routine maintenance and we will not require an application. The face, groins, and toe of the dam were dry with no evidence of seepage. There are two surface water drains for the upper berm and right spillway wall, and these drains were dry. The instrumentation at this dam consists of 15 survey monuments in which twelve monuments are located on the crest and the remaining three are located at the spillway. The latest instrumentation report dated May 29, 2014 covered the period of January 2013 through March 2014. The survey data was reviewed in the previous inspection report and no concerning trends or anomalous behavior was indicated by the data. The current instrumentation submittal is overdue and needs to be submitted annually. The MCWRA has scheduled to install survey monuments on the upper and lower benches in the fall of 2016, and perform annual inspections. The instrumentation data indicated that this dam is performing adequately. Therefore, the existing instrumentation and their monitoring frequency are judged sufficient at this time. Photo 1. A View of the Obermeyer Gates in the fully lowered position. DWR 1261 (rev. 10mg) Sheet 3 of 5 INSPECTIOI. xF DAM AND RESERVOIR IN CER FIED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 05/12/2016 -. "a i Photo 3. The red arrow points to the area in which the minor depressions are located near the left end of the lower bench. DWR1261(rev.10109) Sheet -4 of 5 INSPECTION DAM AND RESERVOIR IN CER. STATUS Name of Darn Nacimiento Dam No. 1008 Date of Inspection 05/12/2016 Photo 4. Survey stakes were placed throughout the upper and lower benches to mark locations to install the new survey monuments. DWR1261(rev.10i09) Sheet 5 of 5 STATE 52115555121 (51521.1( (1.555215555555555 55555151551? 55 ((5555- 5555115555- 55151511 511: 555515 .55- (15515 GF GGEG GNG- GEN ((5515 of (3551 (55515151115 . . .. . . $5.51 N5. (EGGS $5111 {3515.130 11111551155211 E555 I I I ((212-512- .05 551.555}; (215551515 W55 5115; $1511.55! I I I Water 58.35 (555. . (3531.355 5522.555 $525. 55.5;- $31.58 ((22.31. (55.35.55 (5551' (22551;. Water (33555505: ?((292.55 I II I 5111.552; 65552555 $555.12, 51555., .555 55.55.. (355555 (51511.5 Chris: (535.55 R1 255512 K555. (3(55t: 8.55355 5115' (351: (.555 15135 ("51 (215555555 (55151555555 ((2555551) T55 (55(55511'11 ((5515 (.5511. 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(11? 5151555551 53555.- 5135553 55 (211551211 ?555 555515 55 (2151.551551'152'21255 51.55?: 515515 555 55555155 (121552111 5.5.5. 5.225515; ((15 ((5551' 55555555551 (1.51155 5513525 ((1551.15551in55 515551315. (3.5.555 551155.255 (255555555 55.555115151551111. - (1:555:15 (1155555555.. 5155(51'1155 5515. ((15 (555 (555 (?(5515115ch (.555 (355.5. appeared (211551111 55(15551'1 5251155 55.131.111.5555555-5555t115535 55((5f55(5(y (15555155 ((55255 (315.555? 55555155 555555155 with 551.5155 (1555111551 T115. 511155 55125555155 ((15 555(51' 55 ((15 255.5..(5551555552 (21.513551511y 81((?5I?Ggi?i' . I .1 (1 359:5 NG {3.838 013 I 4 2?23?: II 95521.55. G535 8555:5325- gm (1155555 I 134,24 1 (211-132 (3512122511555. ((1551 55.55 "3 51' INSPECTION 1 DAM AND RESERVOIR IN LED STATUS Name of Dam Nacimiento Dam No. 1008 Date of Inspection 1 1/14/2016 Observations and Comments Spillway Sta. 13+50, appeared unchanged as compared with the previous inspection. The abutments appeared stable and the groins appeared normalburied by sandy fill and cannot be inspected. Vegetation control was excellent and no concerning rodent activity was observed. Mr. Moss informed me that MCWRA had delayed the installation of the survey monuments, and they would most likely be included in the next fiscal year budget. The approach, control section, and exit were satisfactorily clear of concerning debris. The spillway concrete structure and visible portions of the Obermeyer gates were inspected by walking the spillway control channel and along the outside ofthe left and right spillway walls. The concrete comprising the weir, invert and channei walls were in overall satisfactory condition. The concrete comprising the spillway structure appeared in satisfactory condition. observed minor spalls between the panel joints and non?concerning surficial cracking on portions of the concrete comprising the spillway structure. The panel joints appeared adequately aligned. requested the repair of the intermittent minor spalls located between the invert panel joints (Photo 2), to which Mr. Moss agreed. The Obermeyer gates were in the fully closed position and were last cycled on April 1, 2016. I performed a cursory inspection of the upstream visible portions of the fully closed gates and they appeared in good condition. MCWRA is required to check the bolt torque after each time the gates impound water and every 5-years if they have not been operated to impound water. The gates last stored water in the spring of 2011, and the bolt torque settings were performed in May 2016. The corrosion on the Obermeyer steel gate panels and bolts has not been removed and touched up with paint, and the delaminated seams have not been repaired as requested during the previous inspection. Mr. Moss informed me that the Obermeyer Hydro lnc. would repair the seams during their site visit to address the other outstanding issues. All the associated Obermeyer gate equipment located in the control building, and in the air?line purge box, appeared to be in excellent condition and weil maintained. The IVICWRA has not addressed all of the action items outlined in our letters dated May 6, 2016 and June 7, 2013 involving the Obermeyer gates; a variance was granted to use the gates this year only in our February 16, 2017 letter due to heavy rainfall. All action items must be addressed by December 31, 2017. Th_ consists of a steel pipe encased in reinforced concrete and is controlled by upstream valves and inline - valves. The upstream valves were last cycled on August 28, 2016, and the five operable valves were fully cycled in April of 2016. None of the outlet valves were operated during this inspection. DSOD last witnessed operation of the outlet system during our March 3, 2014 inspection. DSOD requires that th_ system be cycled at least annually and in our presence every three years. Arrangements need to be made to cycle the upstream and outtets controls during the next maintenance inspection. _Valve #5 has developed a leak within the valve housing and needs to be replaced (Photo 4). The Valve #6 has been removed and replaced by a blind flange. The plug valves and associated piping appeared aged and corroded (Photo 3). Mr. Moss and I discussed the Agency?s plan to replace on valve per year starting in Sheet 2 of 5 INSPECTION K. DAM AND RESERVOIR IN CERT STATUS Name of Dam NaCimientO Dam No. 1008 Date of Inspection 11/14/2016 Observations and Comments Seegage Fiscat Year 2017/2018. Valve #6 is used to supply habitat flow in the river channel and the current ptug valve is not suited to be regulated at less than full flow. This valve is scheduled to be replaced with a ?valve during the 2017/2018 fiscal year. The Owner needs to submit the replacement proposal once it becomes available, and if we determine the work is essentially an in-kind replacement, it will be considered routine maintenance and we will not require an application. The drawdown capability of the low? level outlet is now diminished since two of the six valves are non-functioning. The owner needs to submit a plan and schedule for the replacement of plug valves. The high-level outlet consists of two slide gates located in the center of the spillway. The high-level outlet tunnel was walked and the concrete appeared in satisfactory and stable condition. The high?level slide gates were last cycled on July 18, 2016 with no reported problems. The face and grains were dry, and there was no evidence of seepage. The toe is covered by sandy fill and cannot be inspected for seepage. There are two surface water drains for the upper berm and right spillway wall, and these drains were dry. The instrumentation at this darn consists of 15 survey monuments in which twelve monuments are located on the crest and the remaining three are located at the spiltway. The latest instrumentation report dated June 9, 2014 covered the period of January 2013 through March 2014. The survey . data has been previously reviewed in the May 5, 2015 inspection report and no concerning trends or anomalous behavior was indicated by the data. Annual surveys need to be performed and submitted annually. The had previously scheduled to install survey monuments on the upper and lower benches in the fall of 2016, and then perform the survey on both the existing and new monuments. According to Mr. Moss, the Agency has yet to schedule the installation of the new survey monuments and perform the survey. The owner needs to submit the schedule for installing the new monuments. The previously reviewed instrumentation data indicated that this dam is performing adequately. Therefore, the existing instrumentation and their monitoring frequency are judged sufficient at this time, provided the surveys are performed on an annual basis. . Sheet 3 of 5 a; ?ame Na?imiie?m .. . mam ?310.. $098 . {Bate af'inszpec?on ii i3: LEW-R rigza?: {rem SEE-WE J4 0?