STATE OF CALIFORNIA IL I CALIFORNIA NATURAL RESOURCES AGENCY I . I DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Dam No. 68-7 County Tuolumne Type of Spillway Gated concrete channel spillway crest and 89.88 feet Name of Dam Don Pedro Type of Dam Earth/Rockfill Water is 34.86 feet below darn crest. below Weather Conditions Sunny Contacts Made Peggy Harding with Turlock Irrigation District (TID) Reason for Inspection Outlet Gate Cycling Important Observations, Recommendations or Actions Taken The upstream bulkhead gate and slide gates were cycled during this inspection and they operated satisfactorily. Conclusions . From the known information and Visual inspection, the darn, reservoir, and the appurtenances are judged safe for continued use. Observations and Comments Outlet The low?level outlet works control consist of one upstream bulkhead gate and three tandem pairs of slide gates on and of the low?level outlet tunnel. The upstream bulkhead gate and all slide gates were cycled during this inspection and they operated satisfactorily. Below are the opening and closing times: Slide Gates Gate #1 Gate #2 Gate #3 Open Close Open Close Open Close 4524!] 5102? 4:24? 5l02ll 4124? 5102? Upstream Slide Gates Gate #1 Gate #2 Gate #3 Open Close Open Close Open Close 4135? 6,30? 4135? 6l30l1 4135!} 6130nglp?u?t? Inspected by Param Photos taken? Yes NU Date of Inspection 10/24/2015 cc for Owner/Book Date of Report 11/22/2018 1 of 3 DWR 1261 (Rev. 10:09) Sheet INSPECTIONIUE DAM AND RESERVOIR IN STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection Observations and Comments 2. tandem slide gates. DWR 1261 (rev. 10109) Sheet 10/24/2016 2 of INSPECTION br' DAM AND RESERVOIR IN STATUS Name of Dam Don Pedro Dam No. 68?7 Date of Inspection Observations and Comments 3. Outlet tunnel of the stide gates. DWR 1251 (rev. 10109) Sheet 10/24/2016 Don Pedro Dam, No 68-7 Tuolumne County Picture provided by Ms. Peggy Harding, Chief Dam Safety Engigegg via e?mail on 10/28/16 . CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS STATEOFCALIFORNIA Name of Dam Don Pedro Dam No. 68-7 County Tuolumne Type of Dam Earth/Rock?ll Type of Spillway Gated Concrete Channel Water is 1 12.45 feet below spillway crest and 167.45 feet below dam crest. Weather Conditions Clear and COOI Contacts Made Peggy Harding and Myron McCoy with TID I Reason for Inspection Annual Maintenance Inspection Important Observations, Recommendations or Actions Taken The 72? fixed cone valve at the power tunnel was cycled to its 75% limit with no problems. Arrangements need to be made to cycle this valve 100% to comply with requirement. The tree at the toe of Dike A was also removed, as requested. TID is schedule to replace the power tunnels upstream bulkhead gate and the intermediate fixed wheel gate in 2016/2017. The replacements will be in-kind, with exception to modifying the steel bulkhead gate to a new stainless steel gate. No application will be necessary. Arrangements need to be made for DSOD to witness the fully operation of the gates following the completion of the work. TID has completed work on the diversion tunnels tandem slide gates. All gates were replaced in?kind with new stainless steel gates in 2014/2015. The inclined upstream gate at the diversion tunnel was refurbished in I 2014. Arrangements need to be made for DSOD to witness the full operation of all the diversion tunnel gates. Mrs. Harding agreed to contact us prior to the next scheduled cycling. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments Dams Main Dam: I walked along the right groin and toe ofthe dam, and slowly drove along the crest. The asphalt roadway crest remains in satisfactory condition. Both faces exhibited no signs of instability or distress. The riprap protection along the upstream face appeared stable and intact. Vegetation control along both faces was excellent. The face was covered with low growing well maintained grass. No rodent activity was observed. Auxiliary Dikes: I walked along the crest, groins, and toe of Dikes A, B, C, and the Gatsburg Dike. Each dike is fully exposed above the waterline. The faces of each dike showed no signs of distress or instability. Minor tire ruts were observed along the crest of Dike B, which are not a dam safety concern at this time. Vegetation control along each embankment was excellent. The tree at the toe of Dike A has been removed, as requested. Minimal rodent activity was observed along the embankments of Dikes and C. Rodent control measures need to continue. Spillway The spillway approach, control section, and channel were clear and unobstructed. The epillway was observed from the overhead radial gate structure and from the end of the concrete channel. The radial gates were observed in the closed position and showed no signs of distress. The gate coatings were good. Mr. McCoy reported that the gate controls are lubricated prior to each exercise. All weepholes appeared clear and functional. The concrete?fs 2191! L: Inspected by T. Jimenez - Photos taken? Yes N0 Date of Inspection 1/8/2016 I cc for Owner/Book Date of Report 1/13/2016 11 lb DWR 1261 (Rev. totes) Sheet 1 of 5 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Don Pad/0 Dam No. 58-7 Date of Inspection 1/8/2016 Observations and Comments Outlet surfaces were in satisfactory condition in the approach and channel. Minor spalling, however, was observed below the buttress pier separating the left and middle gates on the invert of the spillway channel. Mr. McCoy mentioned that the area is scheduled for repairs this summer, as part of their regular maintenance. The auxiliary spillway approach, control section, and channel were clear and unobstructed. I walked along the end of the sill. The concrete surfaces were in satisfactory condition with no significant spelling and typical long standing cracking was observed. Mrs. Harding pointed out that several ofthe vertical joints along the sill had been sealed with a Sikaflex type product this past year. Many ofthe joints already show signs of cracking and separation of the joint seal product. Mrs. Harding explained that TID will investigate other alternatives for sealing the joints. Outlet releases can be made from the diversion and power tunnel controls. Diversion Tunnel: The diversion tunnel consists of a 30?foot concrete lined tunnel, controlled by an upstream inclined gate and three pairs of tandem slide gates nearthe center ofthe tunnel. The upstream incline gate was refurbished by the owner in 2014. The gate was locked in the fully open position and observed above the reservoir level. it was found to be in excellent condition. The tandem slide gates were replaced in?kind with stainless steel gates in 2014/2015, no application was required. DSOD last observed the incline gate cycled on 11/23/2010, and the tandem slide gates fully cycled on 9/65/2012. All gates are reportedly fully cycled annually. The tandem slide gates werejust tested a few months prior to this inspection. Mrs. Harding is aware of policy to fully cycle the gates annually and in our presence every three years. She agreed to contact DSOD prior to the next scheduled cycling so we may witness the gate operations. We slowly drove through the access tunnel leading up to the tandem slide gates. The horseshoe shaped tunnel was tight and relatively dry. Only minimal wetness was observed along the tunnel roof and walls. Seepage is collected in the side gutters and is visually monitored by TID. Power Tunnel: The power tunnel consists of an 18?-6? reinforced concrete lined tunnel that transitions to a 16?6? steel lined tunnel. The tunnel is equipped with an upstream bulkhead gate, an intermediate fixed wheel gate, and a 72? hollowjet fixed cone valve (FVC) with a 72" shutoff guard valve. The bulkhead head gate has been removed. The gate has been damaged by microbial disease. The disease has caused numerous voids and damage to the gate. The fixed wheel gate is believed to be in the same condition, but remains operable at this time and is reportedly fully cycled annually. The bulkhead and fixed wheel gates are scheduled to be replaced in 2016/2017. A new stainless steel bulkhead gate will replace the existing steel gate. The work is viewed as an in-kind replacement and will not require an application. The gates will need to be fully cycled in our presence following the completion of the work. The 72? FCV was cycled to the 75?percent limit during this inspection, releasing approximately 3000 cfs. I discussed with Mrs. Harding the Division?s policy to fully cycle the outlet controls. was not prepared to cycle the valve 100% during this inspection. Reportedly the valve has never been cycled past the 75% limit. Mrs. Harding requested time to prepare for a full travel cycling. Arrangements need to be made to fully cycle the 72" FCV to comply with our requirements. If the valve cannot be fully cycled under reservoir head, dry cycling it with the guard valve closed is acceptable. The 72? shutoff guard valve was fully cycled. Operation went smoothly and no issues DWR1261trev.10/09) Sheet 2 of INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Don Pedro Dam No. 68?7 Date of Inspection 1/8/2016 Observations and Comments Seepage were reported. No seepage was observed on the faces, groins, or toe of the main dam or auxiliary dikes. The dam has one seepage weir below the powerhouse. A weir reading was not taken during this inspection. No unusual conditions were noted with the low reservoir level. Instrumentation at this dam consists of survey monuments, cross-arm settlement devices, piezometers, and a seepage weir. The most recent data was submitted on December 23, 2014, and reviewed in our last inspection report. The data indicated that the dam continues to perform satisfactorily. The current instrumentation network is judged adequate, and no additional instrumentation is deemed necessary at this time. DWR1261 (rev. toms) Sheet A Of INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of InspectiOn 1/8/2016 1. Diversion tunnel upstream intake gate wedI looked in the fully open position. 2. 72? FCV fully opened to the 75% limit. DWR 1261 (rev. 10109) Sheet _4_of INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Don Pedro Dam No. 68?7 Date of Inspection 1/ 8/201 6 3. General condition of-th'e powertun-nel-upstream bulkhead gate. Gate has been removed and is scheduled to be replaced due to microbial disease. DWR 1261 (rev. 10109) Sheet 5 of 6 INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection 1/8/2016 xx. 5. iew of the aluxilary spillway from Ihgii??aiai Q?t??ir??Iure. Sheet 6 of STATE OF CALIFORNIA I I CALIFORNIA NATURAL RESOURCES AGENCY . I 1 .I l] I DEPARTMENT OF WATER RESOURCES I I DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name ofDam Don Pedro Dam No. 68-7 County Tuolumne Type of Dam Earth/Rockfill Type of Spillway Gated Concrete Channel Weather Conditions Sunny and warm, 80 degrees F. Contacts Made Peggy Harding and others w/ TID, David Bakker w/ MID. I I Water is 96.5 feet below spillway crest and 151.5 feet below dam crest. Reason for inspection Annual Maintenance Inspection. Important Observations, Recommendations or Actions Taken I requested the owner to remove a small tree growing at the toe of dike Reportedly, the owner has ordered the fabrication of a new bulkhead gate and a new fixed wheel gate to replace the existing gates on the power tunnel during the 2016/2017 irrigation outage. I requested the owner notify DSOD prior to beginning this work so we can determine whether an application will be required. After the inspection, I spoke with Mrs. Harding by email and by phone regarding the operation frequency of all outlet controls, and reminded her of our policy that outlet controls need to be fully cycled annually and in our presence every three years. She agreed to inform me prior to the next full cycling ofthe 72?inch hollowjet fixed cone valve below the power tunnel in September 2015, and I agreed to witness the cycling of the six diversion tunnel slide gates once they have all been replaced and recommissioned in 2016. I Following projected work during the 2016/2017 irrigation outage, all outlet controls will be remotely operable I and with the exception of the bulkhead gate will be cycled annually and in our presence every three years. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments We walked the crest, lower groins, and toe of the main dam, and inspected the face and visible portion of the upstream face. The asphalt crest remains in satisfactory condition with no significant cracking. The embankment remains in satisfactory condition, and showed no signs of instability or distress. The reservoir level was very low on this date, exposing much of the upstream face, and rock slope protection was observed to be uniform, stable, and in satisfactory condition. The face was clear and well-maintained. Vegetation control was excellent and there were no signs of rodent activity. A_u>g We inspected the crests, faces, groins, and toes of the auxiliary dikes, and found them to be in Dikes satisfactory condition with no signs of distress. There was no water against any of the dikes and rodent activity was almost nonexistent. Vegetation control was satisfactory except for a single small tree at the toe of dike which I requested the owner to have removed. Spillway The spillway approach, control section, and channel were clear and unobstructed. The radial gate structure and all skin plates, anchors, radial arms, trunnions, structural members, seals, and gate coatings appeared to be in good condition. The auxiliary spillway sill and all other concrete surfaces appeared to be in satisfactory condition with no cracking or spalling. The radial spillway gates were last cycled by the owner in September 2014. AOK Inspected by A. C. Roundtree Photos taken? Yes No Date of inspection 6/2/2015 I cc for Owner/Book Date of Report 7/23/2015 (J '1I13f if: DWR 1261 (Rev. 10109) Sheet of INSPECTION DAM AND RESERVOIR IN IFIED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection 6/2/2015 Observations and Comments Outlet Seepage Instr. There are two outlet tunnels at this dam, the power tunnel and the diversion tunnel. The power tunnel is equipped with an upstream bulkhead gate, an intermediate fixed wheel gate, and a 72-inch hollow jet fixed cone valve (FCV). The bulkhead gate is known to be in poor condition and currently remains out of the water. The fixed wheel gate is fully cycled every year, but the owner has conservatively estimated that it is also in unacceptable condition given its age and the poor welding logs kept during its construction. Reportedly, the owner has ordered the fabrication of a new bulkhead gate and a new fixed wheel gate to replace the existing gates on the power tunnel during the 2016/2017 irrigation outage. requested the owner notify DSOD prior to beginning this work so we can determine whether an application will be required. The 72?inch hollowjet fixed cone valve (FCV) and all appurtenances appeared to be well?maintained and in good operating condition. The FCV is fully cycled once annually, and it was partially cycled in presence on 9/6/2012. Due to restrictions, the FCV has not been fully cycled in our presence for many years. A more detailed description of the FCV and its operating restrictions appears in the outlet section of the inspection report dated 10/24/2012. Mrs. Harding agreed to inform me prior to the annual cycling of the 72-inch FCV in September 2015. The diversion tunnel is equipped with an upstream inclined gate and three pairs of tandem slide gates near the center of the tunnel. The inclined gate was inspected and refurbished by the owner in 2014 and reportedly remains in good condition. It is cycled every year. It was last cycled in presence during the 11/23/2010 inspection of the diversion tunnel, which found no issues. The six tandem gates are operated several times throughout the year. They were fully cycled in presence during the inspection on 9/6/2012 without any problems. The owner is in the process of replacing all six gates, and will finish the work this year. As the replacement is in-kind, no application has been required. I agreed to witness the cycling of the six tandem slide gates once they have all been replaced and recommissioned in 2016. After the inspection, spoke with Mrs. Harding by email and by phone regarding the operation frequency of all outlet controls, and reminded her of our policy that outlet controls need to be fully cycled annually and in our presence every three years. Mrs. Harding noted that, following the replacement of the six tandem slide gates, the bulkhead gate, and the fixed wheel gate, all outlet controls will be remotely operable and will be cycled annually, with the possible exception of the bulkhead gate, which is a redundant control, and would be cycled with a frequency to be determined following installation. This arrangement is acceptable. There were no signs of seepage at the face, grolns, or toe of the main dam, and all of the auxiliary dikes were completely above water. The seepage weir below the powerhouse read approximately 0.38?, or ~100 (0.22 cfs). Seepage conditions were judged normal. Instrumentation at this dam consists of sixty?eight (68) survey monuments, seven (7) cross-arm settlement devices, thirty?five (35) piezometers, and one seepage weir. The most recent data was submitted on December 23, 2014 and included data through October 2014. Survey Monuments: All monuments are located on the main dam, and are surveyed annually for horizontal and vertical movements. Maximum horizontal movement since the previous survey was 0.042-foot, which is not surprising with the very low reservoir in 2014. Maximum vertical movement since the previous survey was 0.029-foot. No significant radial movement is evident from the data. Sheet 2 of 3 INSPECTION 0F DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection 6/2/2015 Observations and Comments Since the initial survey in 1970, maximum long?term horizontal and vertical movements have been 0.32-foot and 1.08?foot of settlement, respectively; both occur near the maximum section and both are within acceptable limits for a large earth and rockfill darn. Cross?arm Settlement: The cross-arm settlement data continues to show very little movement from year to year, with a maximum consolidation of about 0.08?foot within the last ten years. This is in line with the survey movements recorded, and is considered to be reasonable movement for a large earth and rockfill dam. Piezometers: The dam has four (4) spillway piezometers and thirty-one (3?1)fUnctional embankment piezometers. The spillway piezometers continue to fluctuate with changes in the reservoir elevation and local groundwater conditions, as expected. The piezometers in the main dam are divided into upstream and embankment piezometers, chimney drain piezometers, and foundation piezometers. The upstream embankment piezometers continue to mirror changes in the reservoir elevation. The embankment piezometers and chimney drain piezometers suggest a drier embankment and a phreatic surface which attenuates sharply on the side of the core, indicating that the chimney drain continues to function satisfactorily. The foundation piezometers track the reservoir elevation with substantial attenuation and lag. There are no irregular or aberrant readings in the piezometer data. Seepage Weir: Seepage flows at the weir are heavily influenced by rainfall. Discounting weir readings which occurred during heavy rainfall events, seepage flow during the most recent reporting period peaked at 0.52 cfs, which is normal. Seepage flows remained consistent with prior years' flows and historical averages. The available instrumentation data indicates that the dam continues to perform satisfactorily. The current instrumentation network is judged adequate, and no additional instrumentation is necessary at this time. DWR1261 (rev. 10109) Sheet Of CALIFORNIA NATURAL RESOURCES AGENO . DEPARTMENT OF WATER 1, DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS STATE OF CALIFORNIA 4' I I Name of Dam Don Dam No. 68-7 County Type of Dam Earth/Rockfill Type of Spillway Gated Concrete Channel Water is 66.5 feet below spillway crest and 121.5 feet below dam crest. Weather Conditions Sunny and warm, 80 degrees F. Contacts Made Peggy Harding and others w/ TID, David Bakker w/ MID. Reason for Inspection Annual Maintenance Inspection. Important Observations. Recommendations or Actions Taken The dam and auxiliary dikes are well maintained. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments Dam Outlet Photos taken? cc for vaR 1261 (Rev. 10/09) Sheet 1 of We walked the crest, midway bench, lower groins, and toe of the main dam, and inspected the face and visible portion of the upstream face. The embankment was in satisfactory condition, and showed no signs of instability or distress. Rock slope protection on the upstream face was uniform and in good condition. The face was clear and well-maintained. Vegetation control was excellent. There were no signs of rodent activity. We inspected the crests, faces, groins, and toes of the auxiliary dikes, and found them to be in excellent condition, with good vegetation control and no visible rodent activity. We did not inspect the Gasburg Dike on this date. The spillway approach, control section, and channel were clear and unobstructed. The radial gate structure and all skin plates, anchors, radial arms, trunnions, structural members, seals, and gate coatings appeared to be in good condition. The auxiliary spillway sill and all other concrete surfaces appeared to be in satisfactory condition with no cracking or spalling. The radial spillway gates were last cycled by the owner on 9/3/2013, without incident. The control machinery for the fixed wheel gate on the power tunnel (accessed from the crest of the dam) remains in satisfactory condition. The 72?inch hollow jet FCV and all its appurtenances appeared to be well?maintained and in good operating condition. The diversion tunnel outlet works, including the access tunnel, outlet gate chamber, and all controls for the six tandem outlet gates appeared to be well-maintained and in good operating condition. The six tandem gates were all fully cycled during the previous maintenance inspection on 9/6/2012, and functioned without any issues. The owner plans to replace these outlet gates within the next few years. As the replacement will be in?kind, no application will be required. I last inspected the full length of the diversion tunnel on 11/23/2010, and found no issues. The I I upstream inclined gate was last fully cycled in presence during that inspection. Ami it PFI) Inspected by A C. Roundtree .JlVl Yes No Date of Inspection 6/13/2014 Owner/Book Date of Report 6/27/2014 {It 'iF DAM AND RESERVOIR IN GET STATUS Name of Dam Don Pedro Dam No. 68?7 Date of Inspection 6/13/2014 Observations and Comments Seepage There were no signs of seepage at the face, groins, or toe ofthe main dam, and both of the auxiliary dikes were completely above water. The seepage weir below the powerhouse read approximately 0.40', or ~115 (0.24 cfs). Seepage conditions appeared to be normal. instrumentation at this dam consists of survey monuments, cross-arm settlement devices, piezometers, and one seepage weir. The most recent data was submitted on December 13, 2013 and included data through October 15, 2013. My review of that data is as follows: Survey Monuments: All monuments are located on the main dam, and are surveyed annually for horizontal and vertical movements. Horizontal movements remain small, generally varying about i0.01-foot from year to year. No consistent or significant radial or tangential movement is evident from the graphs. The dam has settled about 0.05?foot at the maximum section in the last ten years. Total settlement since 1970 has been about 0.95-foot. This is within acceptable limits for a large earth and rockfili dam. Cross?arm Settlement: The cross?arm settlement data continues to show very little movement from year to year, by a few hundredths of a foot. Cross?arm readings suggest a total consolidation of about 0.05-foot over the last ten years. Piezometers: The dam has 4 spillway piezometers and 27 functional embankment piezometers. The spillway piezometers continue to fluctuate very with reservoir elevation changes and local groundwater conditions, as expected. The embankment piezometers indicate that the chimney drain continues to function satisfactorily, while the upstream instruments continue to mirror changes in the reservoir level. Piezometer P41 exceeded the owner?s action level by 0.9 feet in January, and piezometer P17 exceeded the owner?s action level by 0.6 feet in July, but both had returned to historic levels by the next reading. The owner investigated these instruments, and as no signs of instability were observed, no action is required at this time. There were no irregular or aberrant readings in the data. Seepage Weir: Seepage flows at the weir are heavily influenced by rainfall. Discounting weir readings which occurred during heavy rainfall events, the normal seepage flow during the reporting period was approximately 0.5 cfs, which is normal. Seepage flows remained consistent with historical averages. The submitted data indicates that the dam continues to perform satisfactorily. No additional instrumentation is judged necessary at this time. Sheet 2 of 5 INSPECTIOF 3F DAM AND RESERVOIR IN FIED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection 6/13/2014 I -. .r 'h I 2. fad-i-al gate structure. Sheet 3 of DAM AND RESERVOIR IN CEF STATUS Name of Darn Don Pedro Dam No. 68-7 Date of Inspection 6/13/2014 4. face and right groin of dam viewed from toe. DWR1261(rev.10l09) Sheet 4 of DAM AND RESERVOIR IN STATUS Name of Dam Don Pedro Dam No. 68?7 Date of Inspection 6/13/2014 . ,rl- I 1 -. 5. Access tunnel remains in good condition. 6. Tandem gate valves remain in good condition. DWR1261 (rev. 10l09) Sheet 5 of CALIFORNIA NATURAL RESOURCES AGENCY: . DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS STATE OF CALIFORNIA - 3 Name of Dam Don Pedro Dam No. 68-7 County Tuolumne Type of Dam Earth/Rockfill Type of Spillway Gated Concrete Channel Water is 37.9 feet above spillway crest and 92.9 feet below dam crest. Weather Conditions Sunny and warm, 80 degrees F. Contacts Made Brad Koehn, Myron McCoy and others w/ TID, David Bakkerw/ MID. Reason for Inspection Annual Maintenance Inspection. Important Observations, Recommendations or Actions Taken Vegetation and rodent control was satisfactory at the main dam and at both auxiliary dikes. The rodent den located along the left groin of the main dam had been backfilled, as requested. The 72-inch hollow jet FCV was cycled to ~12?/o open, and the six tandem outlet gates in the diversion tunnel were all fully cycled on this date. Conclusions From the known information and visual inspection, the dam, reservoir, and all appurtenances are judged safe for continued use. Observations and Comments Dams We walked the crest, upper left groin, midway bench, lower right groin and toe of the main dam, and inspected the face and visible portion of the upstream face. The embankment requested. There were no new signs of rodent activity. We also inspected the crests, faces, groins, and toes of both auxiliary dikes and the the rodent activity previously noted at dikes and appeared to be under control. Spillway The spillway approach, control section, and channel were clear and unobstructed. The radial gate structure, auxiliary 'spillway sill, and all other concrete surfaces appeared to be in satisfactory condition with no new cracking or spalling. All radial gate members, trunnions, seals and coatings appeared to be in excellent condition. The spillway gates are cycled annually by the owner, and were last cycled on 9/21/2012 without incident. Outlet The outlet works access tunnel, outlet gate chamber, and all control machinery for the diversion tunnel appeared to be in good condition. The six tandem outlet gates in the diversion tunnel were all fully cycled during the inspection without any issues. inspected the full length of the diversion tunnel on 11/23/2010, and found no problems. The upstream inclined gate was last fully cycled in presence during that inspection. The control machinery for the intermediate wheel gate on the power tunnel (accessed from the crest ofthe dam) remains in satisfactory condition. The powertunnel and turbine bypass valves was in satisfactory condition, and showed no signs of instability or distress. Vegetation control was excellent. The large rodent den located along the left groin of the main dam had been backfilled, as Gasburg Dike and found all three to be in satisfactory condition. Vegetation control was good, and were not inspected on this date, but the 72?inch hollow jet FCV, was cycled to ~12% open without any problems. 46K s?sm . Inspected by A. C. Roundtree Photostaken? Yes No Date of Inspection - 9/6/2012 cc for Owner/Book Date of Repo? 10/24/2012 LJWR1261 (Rev. 10/09) Sheet '1 of 5 ENSPECTION DAM ANI RESERVOIR IN CER TIEI STATUS Name of Dam Don Pedro Darn No. 68?7 Date of Inspection 9/6/2012 Observations and Comments The 72-inch FCV is only partially exercised each year because of flow restrictions. TID cannot open this valve more than about 10-15% while generating, but neither can the valve be cycled in the dry, because closing the upstream control gate will also shut down all of the turbines in the powerhouse simultaneously. This valve can only be cycled to 100% during a heavy storm event, or dry cycled during a complete outage in which all four turbines are down. - There were no signs of seepage at the face, groins, or toe of the main dam, and both of the auxiliary dikes were completely above water. The seepage weir below the powerhouse read approximately 0.43?, or ~138 (0.31 cfs). Seepage conditions appeared to be normal. Instrumentation at this darn consists of survey monuments, cross-arm settlement devices, piezometers, and one seepage weir. The most recent data was submitted on December 15, 2011. My review of that data is as follows: Survey Monuments: All monuments are located on the main dam, and are surveyed annually for horizontal and vertical movements. Horizontal'movements remain small, generally varying about i0.01?foot from year to year. No consistent or significant movement is evident from the graphs. The dam has settled approximately 0.07-foot at the maximum section over the last 10 years. Cross-arm Settlement: The cross-arm settlement data continues to show very little movement from year to year, by a few hundredths of a foot. Cross?arm readings suggest a total consolidation of about 0.05-foot over the last ten years. Piezometers: The dam has 4 spillway piezometers and 30 functional embankment piezometers. The spillway piezometers continue to fluctuate very with reservoir elevation changes and local groundwater conditions, as expected. The embankment piezometers indicate that the chimney drain continues to function satisfactorily, while the upstream instruments continue to mirror changes in the reservoir level. The current data report notes that piezometers P-28, and have been removed from service because they have been inoperable for over 10 years. There were no irregular or aberrant readings in the data. Seepage Weir: Seepage flows at the weir are heavily influenced by rainfall. Discounting weir readings which occurred during heavy rainfall events, the normal seepage flow is approximately 0.4 cfs, which is normal. Seepage flows were consistent with historical averages. The submitted data indicates that the dam continues to perform satisfactorily. No additional instrumentation is judged necessary at this time. own 1261 (rev.10t09) Sheet 2 of 5 INSPECTION I: DAM AND RESERVOIR IN CER STATUS Name of Dam Don Pedro Dam No. 68-7 Date of Inspection - 9/6/2012 d?heel gaet buse. ?oc?z 1 2. Leftwriloki down toward pfrombWe/thouse firstbench. A Sheet 3 of INSPECTION DAM AND RESERVOIR IN CER STATUS Name of Dam Don Pedro Dam No. 68-7- Date of Inspection 9/6/2012 4. Cycling of the 72-inch RN to Sheet 4 of INSPECTION T: DAM AND RESERVOIR IN CER 1IED STATUS Name of Dam Don Pedro Dam No. 68-7 Date of inspection 9/6/2012 5. All six tandem valves on diversion tunnel at 100% open. 6. Service tunnel in good condition. I DWR1261 (rev. 10mg) Sheet . 5 Of