. /e 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 OrOVilIe Dam No. County Butte Type of Dam earthfill Type ofSpiIIway Gated concrete weir and ungated conc. weir Water is 75.8 feet below spillway crest and 96.8 feet below dam crest. 825.2 Weather Conditions Overcast Contacts Made Kevan Samsam, Paul Dunlap, Pat Whitlock, Jackie Bolf, Kevin Wright Reason for Inspection 2?d annual inspection Important Observations, Recommendations or Actions Taken 0 Seal the shrinkage cracks along the Oroville Dam crest road. . Replace the gallery lighting protective globes to control bulb breakage and possible mercury contamination. - Clean the heavy calcite buildup from the foundation gallery utility conduits. Restore or replace utility lines and grounds as needed. a Clean the bird droppings from the radial gates and screen areas such as those shown in photograph 11. 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 No indications of instability were observed along the dam crest, upstream slope, slope, or abutments. The paved crest road remains in satisfactory condition. The asphalt shrinkage cracks should be resealed. See photograph 1. No significant rodent activity or vegetation problems were observed along the dam. Small trees that occasionally emerge along the upstream slope are removed regularly. The slope had a cover of dry grass and weeds as shown in photographs 2 and 3. Access to the survey monuments and House remains satisfactory. The rock along the upstream slope remains satisfactory, although some breakdown has occurred in limited areas over the years. See photographs 4 and 5. Wave benches have formed, but no corrective action appears to be needed at this time. The left and right foundation galleries were inspected. No unexpected conditions were observed in the left gallery where the first seepage was observed at elevation 798 (reservoir level ~825). Members of the California Conservation Corps recently cleaned the galley steps. I noted that a good deal of the calcite collected in the gutters. See photograph 6. The gutters have since been cleared. Apparently, some ofthe calcite buildup was also cleaned from the old cracks along the walls. At station 53+60, the calcite removal appears to have caused a small increase in seepage from the crack. Seepage was first observed at elevation 756 in the right gallery. The electrical boxes that caught on fire at station 22+50 have been repaired. See photograph 7. The gallery lights in this area are now operable. I noted that the incandescent bulbs have been replaced with fluorescent bulbs. However, many of the protective globes were found stacked at the gallery entra e. Since th new bulbs contain mercury, the globes should be replaced. '6/55/ /0 WPenning rt Inspected by Photos taken? Yes N0 Date of Inspection 5/1/10 cc for Owner/Book Date of Report 6/25/10 DWR 1261 (Rev. 10mg) Sheet of 1_0 ?(dill-1 INSPECTION DAM AND RESERVOIR IN .. IED STATUS Name ofDam Oroville Dam No. 1?48 Date of Inspection 6/1/10 Observations and Comments New pressure gages have been installed at the A-B block piezometer location. See photograph 8. New weirs will be installed along the gutters in the left and right galleries to permit better flow isolation. The heavy calcite buildup that covers the conduits along the gallery walls should be removed. The utility lines and grounding system should be restored or replaced as needed. See photograph 9, for I example. I The S?block area was unchanged and in satisfactory condition. House and House were not entered. The gallery sump pump system appeared to be in satisfactory condition. Saddle Bidwell Canyon Saddle and Parish Camp Saddle Dam were not inspected. The water level was dams well below the upstream toe ofthese embankments. Spillway The Flood Control Outlet structure appeared to be stable and the concrete remains in satisfactory condition. The concrete spalling at the spillway bridge bents appears to have stopped. The diagonal crack on the left bridge abutment remains stable as well. The radial gate hoist deck and hoist equipment appeared to be well maintained. The trunnions and anchor tendons appeared to be in satisfactory condition, as did the wire ropes and pick up assemblies. The pickup assemblies are shown in photograph 10. The rope tension has been balanced at each gate. The radial gates, including the coatings, were generally in satisfactory condition. The bird droppings and debris that has accumulated on the gates should be removed. Areas like that shown in photograph 11 should be screened to prevent birds from entering. The inflatable seals at gates 3 and 5 were restored last November. Gate 4 was complete some time ago. The goal is to complete two gates per year. Cracks and delaminated concrete have been repaired along the spillway chute floor. Some of the repaired areas are visible in photograph 12. The chute walls remain stable and in satisfactory condition. The dentates at the flip bucket appeared to be in satisfactory condition as viewed from the highway across the river. Outlet The river outlet facilities were not reviewed. The outlet chamber remains closed to general access until further notice due to ongoing repairs. The Palermo Tunnel outlet was not inspected. Seepage Seepage has remained fairly stable within the galleries in spite of the rising reservoir. The total I internal seepage remains within the historical trends and is relatively low. The long established wet area at mid-level on the left end ofthe darn has been dry in recent years due to the low reservoir level. During this inspection, the area was green as shown in photograph 3. No other seepage areas were observed on the embankment or groins. Flow thru the seepage measurement weir at the toe of the dam was normal. The uneven jet issuing from the orifice plate was corrected by cleaning the edge of the opening. When flowing properly, the jet is symmetrical and quiet. DWR1261(rev.10f09) Sheet 2 of 10 INSPECTION DAM AND RESERVOIR IN -. IED STATUS Name ofDam Oroville Darn No. 1-48 Date of Inspection 6/1/10 Observations and Comments Instr. Following the inspection, I was provided hydraulic piezometer, seepage, drainage, and turbidity data thru mid-2009. Three hydraulic piezometer locations, P-37, 38, 39, are thought to provide reliable data. All of the rest have been abandoned. All three piezometers have tips at elevation 555 feet and are located across dam station 53+05. P-37 is in the upstream transition. P-38 and P-39 are within the core. All are following historic trends P-38 and continue to read higher than might be expected based on the location within the core. The 08M Division is considering how to implement a recent FERC Part 12 recommendation to install new piezometers that would monitor the phreatic surface across the embankment. The benefits and potential negative impacts of installing piezometers within the core should be considered. Survey monuments have been installed along the upstream and slopes and on the crest of the dam. The latest published data extends thru 2008. 063M is currently processing the 2009 data. The unprocessed 2010 data may be available later this summer. Crest settlement has been minimal. The maximum being about 9-inches at station 53+00 since 1989. Almost no settlement was observed between the surveys done in 2005 and 2008. Settlement and displacement along the upstream and slopes was normal in the 2008 data and was following historic trends. The extensometers and joint monitors are no longer read. The instrument program appears to be adequate in scope and coverage at this time, with the possible exception of the piezometer coverage that is currently being reviewed by the Division. Based on my field inspection, my discussions with field staff, and a review of the available data, the dam appears to be functioning normally. DWR 1251 (rev. 10/09) Sheet 3 of 10 INSPECTION s. . DAM AND RESERVOIR IN JED STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 6/1/10 1. This View of the dam crest shows some of the tension cracks in the asphalt. The cracks should be sealed to control in?ltration. 2. The slope as seen from the left abutment. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 DWR1261(rev.10l09) Sheet 4 of 10 INSPECTION DAM AND RESERVOIR IN JED STATUS Name of Dam Dam No. 1-48 Date of Inspection 6/1/10 3. This View taken from the right gallery access parking area shows the access benches and the green grass associated with the seepage zone mid?way up the slope near the left abutment. 4. The rock along the upstream slope remains in satisfactory condition. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 DWR1261(rev.10109) Sheet 5 of 10 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection 6/1/10 5. This View of the upstream slope was taken from the right abutment. 6. This View of the gallery shows some of the calcite buildup along cracks in the right gallery. Note the ?ow path thru the calcite in the gutter. This buildup resulted from cleaning the stairs. The material is said to have been cleared some time after the inspection. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 Sheet 6 of 10 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. Date of Inspection 6/1/10 8. New gages have been installed on the piezometers at the AB block. DWR 1261 (rev. 10.109) Oroville Dam, No. 1-48 Butte County 6/ 1/10 Sheet 7 of 10 INSPECTION DAM AND RESERVOIR IN .. STATUS Name ofDam Dam No. 1-48 Date of Inspection 6/1/10 9. The calcite buildup at seepage areas within the left and right gallery should be cleaned up. The utilities and grounding system should be restored as needed. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 DWR1261(rev.10l09) Sheet 8 of 10 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection 6/1/10 10. The Wire ropes and pick up assemblies appeared to be in good condition. The rope tension was recently balanced at each gate. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 DWR 1261 (rev.10/09) Sheet 9 of 10 INSPECTION . DAM AND RESERVOIR IN . JED STATUS NameofDam Oroville Dam No. 1-48 Date of Inspection 6/1/10 1 1. Note the bird droppings at the trunnion connections. This will lead to corrosion of the bolts in a critical area of the gate. It is suggested that these areas be cleaned and screened to prevent entry by birds. 12. The concrete along the spillway chute has been repaired. The repaired herringbone crack pattern is said to re?ect the underlying drain system. Oroville Dam, No. 1-48 Butte County WPennington 6/1/10 (?3110109) Sheet 10 of 10