I 6' STATE OF CALIFORNIA CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Dam Orovrlle Dam No. 1-48 County Butte Type of Darn earthfill Type ofSpillway Gated concrete weir and ungated conc. weir Water is 2.3 feet ab0ve spillway crest and 107 . feet below dam crest. W8 815 ft Weather Conditions Sunny and hot Primary contacts Dave Sarkisian and Paul Dunlap from Vinh Tran, Contacts Made Bill Dickens and Joe Eades, OFD- Reason for Inspection annual inspection Important Observations, Recommendations or Actions Taken . The next inspection and PFMA are scheduled for July 2014. Consultant interviews are anticipated during October/November 2013. I As noted in the previous FERC Part Safety Inspection Report .a plan for long?term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented." is working with DSOD to develop a course of action. . Gate 3 at the FCC has been returned to unrestricted operation following the resolution of a binding problem. 0 The river outlet system remains inoperative. The engineering contractor, MWH, is developing plans for restoration of the low level outlet capacity. At some point in the future, a separate project will be developed to increase the drawdown capacity at the dam. - OFD staff should continue to monitor the mid-slope seepage at the left side of the dam embankment. The lush vegetation should be trimmed low to facilitate monitoring activity. A means of monitoring the extent of the seepage area should be developed and implemented. Regular visual monitor the irregular rock fill along the upstream side of the darn should continue. Wave erosion appears to be disturbing this material. . Clear the trees that are encroaching along the left and right sides of the flood control outlet chute. . Crest roadway paving is scheduled for 2013, but will likely be delayed. - Over the past few years seals have been replaced on five of the flood control outlet gates. Work on the remaining gates will be delayed until at least next season. Conclusions Based upon my information review and my inspection, the dam, reservoir, and appurtenances are judged safe for interim use pending restoration of adequate drawdown capacity, completion of Category 2 radial gate recommendations, and implementation of a plan for long term monitoring of the Oroville Dam phreatic surface. Observations and Comments Da_m The usual asphalt cracks were observed while walking the crest roadway. See photograph 1, for example. The surface remains satisfactory for continued use pending completion of an upcoming repaving project. The shoulder ofthe crest has been built up to arrest slope erosion and protect the crest survey monuments. See photograph 2. The embankment was observed from the crest road, the right and left groins, the survey monument benches, and from the Elevation 815 bench on the upstream slope. No signs of instability were observed along the slope or the adjoining abutment areas. See photographs 3 through 6. Rodent control was satisfactory. Vegetation control was also satisfactory, with the exception of the long- standing seepage area at mid?level along the left slope. This part of the embankment Inspected by WPennington Photos taken? Yes N0 Date of Inspection 7/15-17/2013 cc for Owner/Book Date of Report 9/20/13 own 1261 (Rev. 10109) Sheet 1 of 18 We 61/23/13 INSPECTION OF DAM AND RESERVOIR iN STATUS Name ofDam Dam No. 1-48 Date of Inspection 7/15?17/2013 Observations and Comments Spillway typically ranges from clamp to wet during the year. The tall weeds should be cut low to facilitate seepage monitoring. See photograph 7. The reservoir was encroached on the central portion of the Elevation 815 bench. This is likely due to the long term settlement along this part of the embankment. The upstream rock slope remains uneven in some areas, probably due to wave action. Occasional rock breakdown was also evident. The slope should be visually monitored, as has been done in the past. Access to the survey monuments and House was satisfactory. Conditions at House remain much improved. The seepage flow from House was normal. The inspection team walked the left gallery down to the emergency exit tunnel and exited by way of the power house. The first water was from a drain pipe at elevation 798. We noted that the most seepage and cracking in this gallery was along grade transitions. See photograph 8, for example. At a location about 8?feet from the drain weir at station 49+60, a small vertical stream of water was exiting from the drain channel at about 1/2 gpm. See photograph 9. Another small stream was seen at station 48+80. Photograph 10 is a view looking along the emergency exit tunnel towards the power house access. Conditions appeared to be normal. However, the wall drains should be checked to see if some of them are blocked. We walked the right gallery to the sump. Then we ascended the left gallery to the emergency exit tunnel where we exited to the powerhouse. The first water in the right gallery was observed at Elevation 758 feet. Conditions in the gallery were normal. At the entrance to the core block the usual widely spaced cracks with calcite were observed. The S?block area and access were unchanged and in satisfactory condition. See photograph 11. The gallery seepage totalizing weirs are shown in photograph 12. Flow was normal. Bidwell Canyon Saddle Dam: The reservoir level was well below the upstream toe of both embankments. The gravel crest roadway remains in good condition. No signs of instability were noted along either section of the embankment. See photographs 13 and 14. Vegetation and rodent control remain satisfactory. The toe drain outfall remains clear. The equestrian trail previously observed along the slope of the west embankment has been backfilled, as requested. Photograph 16. Parish Camp Saddle Dam: The reservoir level was well below the upstream toe of the embankment. The gravel crest roadway remains in good condition. No signs of instability were noted. See photographs 15 and 16. Vegetation and rodent control remain satisfactory. The erosion areas along both groins have been leveled with rock and remain in satisfactory condition. The Flood Control Outlet structure (FCO) was viewed from the service deck (top), the radial gate hoist deck, the roadway bridge, and the trunnion inspection deck. The discharge chute was DWR1261 (rev. 10:09) Sheet 2 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date of inspection 7/ 1 5-1 7/201 3 Observations and Comments inaccessible clue to the seal leakage flow and our concern for worker safety. The chute was observed from the FCO decks and from the opposite side of the river. The service deck is shown in photograph 17. No signs of structural distress were noted, and the concrete was in satisfactory condition. Bulkheads and a spreader bar are stored at the north end of the deck. Bulkheads are also stored in vertical slots that extend into the block below the deck level. The upstream side ofthe FCO is shown in photograph 18. Conditions along the face were normal. The inlet training walls appeared to be stable and in good condition. Nothing unusual was observed along the hoist deck. Photograph 19. The radial gates were inspected by looking down from the hoist deck and by observation from accessible locations along the trunnion inspection deck. No obvious problems with the gate members were observed, other than the need for cleaning. See photograph 20, for example. The gates functioned normally during the last test, except for Gate 3, which had an apparent binding problem. This situation is said to have been corrected and Gate 3 is in full operational status. Gate seal leakage is still a problem, even at gates 1 through 5 where the seals and associated operating hardware have been replaced. Replacement of the seals at one of the remaining three gates was initially scheduled for this season, but will likely be delayed until next fall. A number of Category 2 recommendations were made as a result of the September 2012 gate inspection by a contract climb team from HDR. inc. The recommendations will be completed on a priority basis. Nothing unusual was observed during a cursory inspection of the trunnions and trunnion anchors as seen from the trunnion inspection deck. See photograph 21. Ultrasonic testing of the trunnion beam anchor rods has resumed. No spalling was along roadway bridge bents that experienced damage extending over several yea-rs, but eventually stopped and has not reappeared for a number of years. It was noted that the left bent tattletale paint had been reapplied. See photograph 22. The reason for this was not known by those present. The paint used to check for extension of the diagonal crack on the left bridge abutment was undisturbed. Stable conditions have been observed for a number of years. The emergency spillway weir and apron appeared to be well aligned. No signs of instability were observed. The concrete remains in satisfactory condition. See photograph 23. The FCC discharge chute walls appeared to be stable and in satisfactory condition. See photographs 24 and 25. The chute floor was too hazardous to traverse due to the gate seal leakage. Nothing unusual was observed from the hoist deck or from a vantage point on the opposite river bank. The wall drains were dry. The river outlet system remains inoperative pending completion of an ongoing project to restore the function of the outlet system. DWR1261 (rev. 10mg) Sheet 3 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1?48 Date of Inspection 7/15?17/2013 Observations and Comments Seepage Oroville Dam: The seepage flow within the galleries was within historical trends and remains relatively low. Measurement weirs located along the drain gutters can be used to the check the flow over a specific reach of the gallery. Seepage within the emergency exit tunnel appeared to be normal. However, some of the drain piped may need to be cleaned. Flow thru the seepage measurement weir at the toe of the dam was normal. During the inspection we noted a small spring in a tree lined channel located from the right groin. The elevation is perhaps 550 to 600 feet. The area around the small undercut pool was wet for a short distance. will monitor this area from time to time. The long established wet area at mid-slope on the left end of the dam remains active. The field staff should continue to monitor the area for unexpected changes in the seepage pattern or flow quantity. A means of monitoring the extent of the seepage area should be implemented so that year to year changes can be recorded. In addition, the vegetation in this area should be kept low to facilitate the monitoring process. Photograph 7. Bidwell Canyon Saddle Dam: The toe drain system outfall beyond the toe of the west embankment was dry. The foundation seepage that migrates from Miners Ranch reservoir to a seepage area upstream from the south embankment is distributed over a wide area defined by trees and brush. A long standing concentrated seepage at the head of this area was flowing clear, as usual, and within observed limits. Photograph 14. The concentrated seepage area should be kept clear of vegetation to allow visual monitoring of flow changes. No other seepage areas were observed. Parish Camp Saddle Dam: No seepage was observed at this location. The latest monitoring information on file is the 2012 which covers the period from 10/1/11 to 9/30/12. This report was supplemented in the field with additional data through June 2013. The following comments are provided. Most are repeated from the January 2013 inspection report. Oroville Dam embankment: Three piezometers remain functional out of the original 56 that were installed at the time of construction. These are P?37(upstream transition), and 39(core). They appear to provide little useful information, but will be read until they are no longer func?onaL The last FERC Part Safety Inspection Report states that .a plan for long?term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented.? is working with DSOD to develop a course of action. Survey monuments are located along the upstream and slopes and along the crest of the dam. Crest settlement remains minimal. The maximum movement being about 9-inches at station 53+00 since 1969. Settlement and displacement along the upstream and slopes remains normal and appears to be stabilizing. Sheet 4 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date of inspection 7/15-17/2013 Observations and Comments The DWR Precise Survey crew has been using GPS technology to measure horizontal deflection of the embankment monuments since 2003. However, the data has been questioned by DSOD and inspectors. While the latest GPS technology is much improved, it may not be sufficient for evaluating long term settlement and deflection. will work with DSOD to resolve the issue. Bidwell Canyon Saddle Dam: Settlements and deflections are small and as expected. Parish Camp Saddle Dam: Settlements and deflections remain small and as expected. The instrument program for Oroville Dam is satisfactory on an interim basis, pending a review of the phreatic surface monitoring capability and a review of the GPS approach for monitoring horizontal deflection. The instrument program at the saddle dams is satisfactory. Based on my field inspection, my discussions with field staff, and my review of the available data, Oroville Dam and the saddle dams appear to be functioning normally. 1. This view looking along the crest towards the left abutment shows the asphalt cracking typical of the roadway. A repaying project was scheduled for this year, but may well be postponed due to the impacts of higher priority projects. DWR1261(rev.10l09) Sheet 5 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Darn Oroville Dam No. 1-48 Date of inspection 7/15-17/2013 2. A road base type material was used to restore the shoulder of the crest road. Erosion was undermining the crest survey monuments and causing other problems. The vault in the picture is for a strong motion seismograph. 3. Upstream slope as seen from the sloping intake structure. A buoy line in the lower part of the picture keeps boats away from the intake structure. DWR 1261 (rev. 10109) Sheet 6 0f 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-43 Date of Inspection 7/15?17/2013 5. The right abutment is visible in this picture taken from the dam crest. DWR 1261 (rev. 10109) Sheet 7 0f 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date of Inspection 7/15-17/2013 6. This View taken from the right gallery access parking area shows the left abutment and a path used to access survey monuments (left). 7. The left groin is visible in this picture looking down slope near the left abutment. The tall weeds are the result of good growing conditions cause by seepage on the face of the dam. The vegetation in this area should be kept low to facilitate the observation of seepage conditions throughout the year. DWR1261(rev.10f09) Sheet 8 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Dam Dam No. 1-48 Date of Inspection 7/15-17/2013 8. This picture taken in the left gallery shows how cracking and seepage seems to occur more at a change in the gallery grade. 9. A small vertical jet of water, perhaps 1/2 at the arrow, in the left gallery gutter near the seepage measurement weir at station 49+60. DWR 1261 (rev. 10109) Sheet 9 Of 18 INSPECTION OF DAM AND RESERVOIR IN .ED STATUS Name of Dam Oroville Dam No. 1-48 7/15-17/2013 Date of Inspection 10. This View is looking along the emergency exit tunnel towards the power house access. Conditions appeared to be normal. The wail drain pipes should be checked for clogging. 11. This is the location in the S?Block gallery where the piezometer tubing bundle was cut off after the piezometers failed many years ago. The dripping water from the bundle is observed for changes in flow rate and turbidity as it enters the collection pan at the bottom of the picture. The pan is drained to the gutter system. Sheet 10 of 18 DWR 1261 (rev. 10/09) INSPECTION OF DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 7/15-17/201 3 1" Idig'r-frAq: . .v 13. View looking west along the main embankment of the Bidwell Canyon Saddle Dam. The Miners Ranch reservoir backs up against the toe of the saddle dam. DWR1261(rev.10l09) Sheet 11 of ?18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Dam Oi?OViIle Dam No. 1-48 Date of Inspection 7/15?17/201 3 14. This View looking west shows the upstream slope of the main embankment at Bidwell Canyon Saddle Dam. The rock slope protection remains in good condition. A long standing concentrated seep is located at the arrow. The seepage originates at the Miners Ranch reservoir, photograph 13, and flows through the foundation before it discharges beyond the upstream toe of the embankment. 15. Looking north along the upstream slope of the west embankment at Bidwell Canyon Saddle Dam. owa1251 (rev. 10/09) Sheet 12 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date of Inspection 7/15-17/2013 16. Looking north along the slope of the west embankment at Bidwell Canyon Saddle Dam. The horse trail on the slope, arrow, has been backfilled. i i- 'l i . sis, 17. The FCC service deck is shown. Some of the inlet bulkheads are visible at the north end of the deck. DWR1261 (rev. 10mg) Sheet 13 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1?48 Date of Inspection 7/15-17/2013 c. 3 :ilI.IEiH1ilii l' I: ?~pr '"ii?il' ?1 ?3 gift] 18. The upstream side of the FCO is shown. Conditions appeared to be normal. The reservoir was about 1.5 feet above the sill. 19. This View is looking left along the FCO hoist deck. Conditions were normal. DWR1261 (rev. 10109) Sheet 14 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Dam No. 1-48 Date of Inspection 7/15-17/2013 21. Looking right along the trunnion deck at the FCO. Conditions appeared to be normal. Ultrasonic testing of the anchor rods has resumed. Sheet 15 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS NameofDam Oroville Darn No. 1?48 Date of Inspection 7/15-17/2013 1-11" WWI.- . Tan?. Ila-mm Jazmin -- ?v .nu- 22. The tattletale paint along the left bent of the roadway bridge is used to monitor spelling. This hasn't been a problem for a number of years. The paint has been reapplied in the area shown. The reason was not known to those present. 23. View right along the side of theemergency spillway weir. The structure appeared to be stable and the concrete was in satisfactory condition. Sheet 16 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Dam Oroville Darn No. 1-48 Date of Inspection 7/15?17/2013 24. The left side of the FCO discharge chute is shown. The wall appeared to be well aligned and stable. The trees encroaching on the wall should be cut back or removed. DWR1261 (rev. 10109) Sheet 17 of 18 INSPECTION OF DAM AND RESERVOIR IN STATUS Name of Dam Dam No. 148 Date of Inspection 7/15-17/2013 25. The right wall of the FCO discharge chute is shown. The wall appeared to be well aligned and stable. The trees encroaching on the wall beyond the vertical curve should be cut back or removed. Sheet 18 of 18