STATE OF CALIFORNIA JALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name of Darn Orovrlle Dam No. 1-48 County Butte Type of Dam earthfill Type of Spillway Gated concrete weir and ungated conc. weir Water is 17.3 feet above spillway crest and 91 .1 feet below dam crest. ws 830.9 ft Weather Conditions Cold with light wind Contacts Made David Sarkisian and Paul Dunlap from HQ, and OFD staff Reason for Inspection annual inspection Important Observations. Recommendations or Actions Taken a As noted in the most recent FERC Part Safety Inspection Report plan for long-term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented." will work with DSOD to develop a course of action. . Gate 3 at the flood control outlet should be restored to full operation at the earliest possible date and the recommendations of the contract gate inspection team should be addressed on a priority basis. 0 The river outlet system remains inoperative pending restoration of drawdown capacity. A large kickoff meeting was held on 1/25/13 to discuss immediate and long-term drawdown capacity requirements. Those present included management from DSOD, FERC, representative from the owner?s engineer and support staff from DSOD and - Continue to monitor the mid-sl0pe seepage along the left side ofthe slope. 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. Continue visual monitoring ofthe irregular rock fill along the upstream side as discussed during the inspec?on. . The DOE Corrosion Engineering Branch has evaluated the calcite encrusted and corroded utility lines in the dam access galleries, as requested. A number of corrosion related recommendations have been made and will be implemented. . As requested, the openings at the connection between the radial gate arms and the trunnions have been covered with wire mesh to stop bird nesting. . Clear the trees along the left and right sides of the flood control outlet chute. See photograph 14, for example. . Crest roadway paving is scheduled for 2013. Conclusions Based upon my review of information and my visual inspection, the dam, reservoir, and the appurtenances are judged safe for interim use pending restoration of adequate drawdown capacity, resolution of the radial gate issues, and implementation of a plan for long term monitoring of the phreatic surface within the Oroville Dam embankment. Observations and Comments Dam The usual stress cracks were observed along the crest roadway. See photograph 1, for example. The surface remains in satisfactory condition, pending completion of a repaving project scheduled for 2013. Vegetation and rodent control were satisfactory on the embankment. The slope had a cover of low, dry grass and weeds, as shown in photographs 2 through 4. The exception was the long-standing seepage area at mid-level along the left side of the embankment. Lush weeds were Inspected by WPennington ,1 3 Photos taken? Yes No Date of Inspection 1-8 and 1-9, 201,6} I ccfor Owner/Book Date of Report Sheet 1 of 14 tZ/i?tai? Witt/i3 INSPECTION DAM AND RESERVOIR IN ED STATUS Name ofDam Dam No. 1-48 Date of Inspection 1?8 and 1-9, 2013 Observations and Comments Sgillway DWR 1261 just starting to emerge in this area. See photograph 2. The embankment is typically damp in this area for a large part of the year, but no active flow was observed. Also see the seepage paragraphs below. The upstream rock slope remains uneven in some areas, probably due to wave action. These areas should be visually monitbred, as has been done in the past. Any observed movement should be investigated and reported to DSOD. The remainder ofthe visible rock along the upstream face was satisfactory. See photographs 5 and 6. Occasional rock breakdown has occurred over the years. Access to the survey monuments and House are satisfactory. Conditions at House remain much improved, and seepage from the collection system remains normal. The inspection team walked the right gallery down to the sump and walked the left gallery to the emergency exit tunnel where we diverted to the power house. No unexpected conditions, new cracks, or other problems were encountered in the gallery areas that we inspected. Seepage is discussed below in the seepage paragraphs. The mineral deposits on the gallery utility lines have been inspected by the Corrosion Engineering Branch at DOE, as requested. A number of recommendations were made regarding corrosion management and replacement of corroded metal parts. The S?block area and access were unchanged and in satisfactory condition. We noted that some of the couplers along the sump pump discharge line have been restored by replacing bolts and removing localized corrosion. Bidwell Canyon Saddle Dam: This feature was inspected on 1-9-13. 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 10 through 13. Vegetation and rodent control were satisfactory. Bait stations were noted at both embankments. The toe drain outfall remains clear. An equestrian trail was again observed along the slope of the north?south embankment. See photograph 10. This trail should be obliterated and the riders should be encouraged to use the access at each end of the embankment. Parish Camp Saddle Dam: The embankment will be inspected later in the year. The emergency spillway weir appeared to be stable and well aligned. The concrete comprising the emergency weir and the flood control outlet (FCO) headworks appeared to be in satisfactory condition. No signs of instability were observed at the FCO. See photographs 15 through 17. The orange monitoring paint used to detect concrete spalling at the spillway bridge bents was undisturbed. The orange paint used to check for extension or spreading of the diagonal crack on the left bridge abutment was also undisturbed. Stable conditions have been observed for a number of years. The FCC chute walls appeared to be stable and in satisfactory condition. See photograph14, for example. 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 drains along the left wall were flowing. (rev. 10mg) Sheet 2 of 14 INSPECTION DAM AND RESERVOIR IN ED STATUS NameofDam Oroville Darn No. 1-48 Date of Inspection 1-8 and 1-9, 2013 Observations and Comments Nothing of immediate concern was observed during the inspection ofthe radial gates. A contract climbing team inspected the side of all eight radial gates from September 5 to September 2012. A number of Category 2 recommendations were made. In a report dated December 13, 2013, the team found the gates to be safe for continued Operation. plans to address the recommendations on a priority basis. DSOD should be included in the decision process. The radial gate hoist deck and equipment appeared to be well maintained. Possible wire rope issues are addressed in the climb team report. The radial gates functioned normally during the last test, except for Gate 3, which has been locked out until a binding problem is corrected. The trunnions and anchor tendons appeared to be in satisfactory condition, photograph 18. The openings at the connections between the gate arms and the trunnions have been sealed with wire mesh to prevent bird nesting. See photograph 19. Radial gate seal leakage remains a problem. Replacement of the original seals at three of the radial gates has been completed. Outlet The river outlet system remains inoperative pending completion of an ongoing project to restore drawdown capacity. Seepage The total internal seepage within the galleries was within historical trends and remains relatively low. Measurement weirs located along the gallery gutters. see photograph 7, can be used to the check the flow over a specific reach of the gutter system. The old method of measuring individual drain flows has been abandoned. The seepage drain outfalls within the emergency exit tunnel may need to be cleaned. See photograph 9, for example. 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. Flow thru the seepage measurement weir at the toe of the dam was normal. No other seepage was observed on the embankment or groins. Instr. The latest published monitoring information is included the 2012 which covers the period from 10/1/11 to 9/30/12. Oroville Dam embankment: Three piezometers out of the original 56 remain functional. These are P-37(upstream transition), and The most recent FERC Part Safety Inspection Report states that plan for long-term monitoring of the phreatic surface within the dam embankment needs to be developed and implemented.? will work 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 since 1969. Settlement and displacement along the upstream and Sheet 3 of 14 INSPECTION 0r DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1?48 Date of Inspection 1-8 and 1-9, 2013 Observations and Comments slopes remains normal and appears to be stabilizing. 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 movenment trends. will work with DSOD to resolve the issue. Bidwell Canyon Saddle Dam embankments: Settlements and deflections are small and as expected. The seepage from Miners Ranch Dam reservoir that migrates to the upstream toe of the saddle dam was small, and appeared to be within observed limits. Parish Camp Saddle Dam embankment: 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. Sheet 4 of 14 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection ?1-8 and 1-9, 2013 1. This View is looking northwest at some of the asphalt cracks along the crest roadway. A repaying project is scheduled for 2013. The crest is satisfactory pending completion of the paving project. 2. The slope appeared to be stable from this vantage point at the left abutment. Low grass and weeds dominate the cover, except at the left abutment seep area. See photograph 3. Oroville Dam, No. 1-48 Butte County DWR1261(rev.10l09) Sheet 5 of 14 INSPECTION Ol- DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1?48 Date of Inspection 1-8 and 1?9, 2013 WPennington 1/8-9/2013 3. A portion of the traditional seepage area at mid-slope along the left side of the clam was partly covered by emerging hydrophilic plants. This area should be kept clear so it can be monitored easily for changes in seepage. 4. This View is looking towards the left abutment from the gallery access parking area at the right abutment. Oroville Dam, No. 1-48 Butte County WPennington 1/8-9/2013 DWR1261 (rev. 10109) Sheet of i INSPECTION OI- DAM AND RESERVOIR IN STATUS NameofDam Dam No. 1-48 Date of Inspection 1-8 and 1-9, 2013 5. View of the upstream slope as seen from the left abutment. 6. View of the upstream slope looking towards the left abutment. The penstock intake structure is visible in the background. Oroville Dam, No. 1-48 Butte County WPennington 1/8?9/2013 Sheet 7 of 14 INSPECTION OI- DAM AND RESERVOIR IN uz'D STATUS Name ofDam Oroville Darn No. 1-48 Date of Inspection 1-8 and 1-9, 2013 7. This is one of the newer seepage weirs that were installed in the seepage galleries so that areas of I increased seepage can be easily isolated and evaluated. 8. This is one of the calcite encrusted areas in the right gallery that was evaluated by the Corrosion Engineering Branch of DOE. Areas like this will be cleaned and protected. Oroville Dam, No. 148 Butte County WPennington 1/8-9/2013 DWR 1261 (rev. 10109) Sheet 8 of 14 INSPECTION OI- DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date 1-8 and 1-9, 2013 9. These drain pipes within the Emergency Exit Tunnel, arrows, were leaking at the joints and may be blocked. The need for cleaning should be checked and repairs should be made as needed. 10. This View of Bidwell Canyon Saddle Darn shows the north-south section of the embankment. The crest and slope remain in good condition overall. Refer to the inset and arrows showing the location of a horse trail that should be backfilled. Oroville Darn, No. 1?48 Butte County WPennington 1/8/9/2013 DWR 1261 (rev. 10109) Sheet 9 of 14 INSPECTION DAM AND RESERVOIR IN STATUS Name ofDam Dam No. 1-48 Date of Inspection ?1-8 and 2013 11. This View of Bidwell Canyon Saddle Dam shows the upstream toe and right groin of the north-south embankment. The conditions shown are typical of the upstream slope. 12. This View of Bidwell CAnyon Saddle Dam shows the crest and slope of the east?west section of the embankment. Conditions remain satisfactory. Bait stations are used to control rodent activity along both sections of the embankment. Oroville Dam, No. 1-48 Butte County WPennington 1/8-9/2013 DWR1261(rev.10l09) Sheet 10 of 14 INSPECTION OI- 0AM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1?48 Date 1-8 and 1-9, 2013 13. Brush and trees at the arrows will be cleared from the side of the Bidwell Canyon Saddle Dam east-west embankment. The low weeds do not impede the inspection process or provide significant cover for rodents. The reservoir at left is the Miners Ranch Dam impoundment, which stores water against the saddle dam. 14. The flood control outlet gate seal leakage and drain flow are visible. The trees and brush shown within the ovals should be removed by November 1, 2013. Oroville Dam, No. 1?48 Butte County WPennington 1/8-9/2013 (rev. 10:09) Sheet 11 of 14 INSPECTION OI- LIAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date 1-8 and 1-9, 2013 15. The upstream side of the flood control outlet headworks is shown. No signs of structural distress were observed, and the concrete remains in satisfactory condition. The pier noses and inlet training walls were stable appearing and in satisfactory condition. 16. The FCC headworks, upper deck, hoist deck, and bridge are visible in this View looking northwest. The discharge chute is at left in the picture. No signs of structural distress were observed. Oroville Dam, No. 1-48 Butte County WPennington 1/8-9/2013 DWR1261(rev.10l09) Sheet 12 of 14 INSPECTION 0r DAM AND RESERVOIR IN STATUS NameofDam Oroville Dam No. 1-48 Date 1?8 and 1-9, 2013 17. This View of the FCO is looking southeast. Some of the stoplogs for the upstream side of the radial gate inlets are at left in the picture. The FCC discharge chute is at the far right. 18. This is the trunnion walkway at the F00. The trunnion beams are at right. A typical anchor tendon cover is at the arrow. The covers are intended to control the environmental conditions at the anchors. Oroville Dam, No. 1-48 Butte County WPennington 1/8?9/201 3 DWR1261 (rev. 10109) Sheet 13 of 14 INSPECTION Or LIAM AND RESERVOIR IN STATUS Name ofDam Orovilie Dam No. 1-48 Date of Inspection 1-8 and 1-9, 2013 19. 'Wire mess has been installed at the FCO radial trunnions to prevent birds from nesting within the open spaces. Oroviile Darn, No. 1-48 Butte County WPennington 1/8-9/2013 Sheet 14 of 14