If? STATE OF CALIFORNIA In CALIFORNIA NATURAL RESOURCES AGENCY DEPARTMENT OF WATER RESOURCES DIVISION OF SAFETY OF DAMS INSPECTION OF DAM AND RESERVOIR IN CERTIFIED STATUS Name Of Dam Oroville Darn No. 1-48 County Butte Type of Dam earthfill Type of SpiIIWay Gated concrete weir and concrete chute Water is 94.6 feet below spillway crest and 202.8 feet below dam crest. WS 719.2 Weather Conditions Sunny and warm Contacts Made Dave Panec, et. al. from DWR, and FERC Part 12 Board Members Reason for Inspection Annual inspection Important Observations. Recommendations or Actions Taken - Clean the heavily calcified joints within the foundation gallery. . Restore the gallery utility lines. . Repair the rills along the groin Of the Parish Camp Saddle Dam. Conclusions From the known information and visual inspection, the dam, reservoir, and the appurtenances arejudged safe for continued use. Observations and Comments Da_m Main Dam: The crest and embankment are shown in photographs 1 thru 6. The embankment appeared to be stable. NO rodent activity was Observed. The asphalt paved crest road remains in satisfactory condition. The cracking noted appears to be superficial. Regular crack sealing should continue. A low, dry, grass cover remains along the slope. The observed survey monuments were well maintained. The heavy rOCk along the upstream slope remains stable and mostly sound. Some rock breakdown, settlement, and wave benching has occurred over the years, but is not significant enough to require attention. The few small trees noted along the upstream slope will be cleared. The foundation gallery was entered from the left side and traversed to the right access. The galleries have very little seepage for such a large dam. Cracks are present along the gallery walls, but no new cracks were Observed. Some pass seepage and have a calcite buildup. See photograph 7 as an extreme example of the buildup that should be removed. First water was Observed at about elevation 798. Note that the reservoir was at elevation 719. The right gallery has less cracking and is generally in better condition. An electrical panel at about station 22+50 caught fire some time ago leaving part of the gallery without lights. See photograph 8. A temporary string of lights has been installed with extension cords. The utility system should be cleaned and restored. BI?dwel/ Bar Canyon Saddle Dam: This site was inspected on 8/27. Oroville Reservoir was well below the toe Ofthe embankment. The Miner Ranch reservoir was against the toe of the south embankment as is the usual case. Both embankments appeared to be stable. No significant rodent activity or Objectionable vegetation was Observed. See photographs 9 thru 12. The crest Of each embankment was in good condition. No signs Of settlement were noted. The rock wave protection along the upstream slopes was sound. NO benches have developed. The slopes had a dry grass cover. The trees and brush at the toe of the west embankment will be remov to Expos the toe drain alignment. 5 2; ?zf? Inspected by WPen gton Photos taken? Yes No Date of Inspection 8/25 thru 8/27 2009 cc for Owner/Book Date of Report 12/14/2009 DWR 1261 (Rev. 10mg) Sheet 1 of 17 a? I 27/] INSPECTION of DAM AND RESERVOIR IN IED STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection BI25 thru 8/27 2009 Observations and Comments Spillway The only seepage observed was at the south embankment. Water from the Miners Ranch Reservoir traditionally flows back thru the rock foundation at a rate of a few gallons per minute when Oroville Reservoir is low. The site is visually monitored regularly. However, this clear seepage does not appear to be a problem at this time. Parish Camp Saddle Dam: This inspection occurred on 8/25. The reservoir was far below the upstream toe. The embankment appeared to be stable and no significant vegetation or rodent activity was observed. See photographs 13 and 14. The gravel crest was level. No signs of settlement were observed. The rock wave protection along the upstream slope and the cobble along the slope remain sound. The erosion areas along the groins should be protected. No seepage was found as would be expected with the low reservoir conditions. An overall view of the flood control outlet structure is shown in photograph 15. The upper deck appeared to be unchanged. No signs of settlement or other structural distress were observed. The stop logs stored at the north end of the deck remain in good condition. Consideration should be given to protecting the propane tank at the left side of the deck. Gate 7 was open and resting on a support to provide access for the upcoming chute floor repairs. Nothing unusual was observed during a cursory review of the radial gate hoist equipment and cables. See photograph 16. The observation deck adjacent to the trunnion anchors remains in satisfactory condition. See photograph 17. Spalling at the bridge bents remains in check based on the undamaged indicator paint applied over the previously spalled areas. The diagonal crack at the left bridge bent remains unchanged. Photograph 18. The radial gates were inspected from the observation deck and from the chute floor. The gate members, trunnions, and anchors appeared to be in good condition. The coatings are holding up well. See photograph 19. The excessive bird droppings should be removed from the trunnion areas and the debris should be cleared from the confined areas along the bottom of the gates. The Oroville Field Division is planning to repair one or two gate seal systems each year. Three sets have already been completed. The flood control outlet chute remains in satisfactory condition. See photographs 20 thru 23. Minor chute floor repairs will begin in the near future. A contractor crew was marking areas for repair during our inspection. The chute walls were aligned, and the concrete remains in satisfactory condition. Widely Spaced, tight, vertical cracks are visible along the walls. Notably, the walls had cracks extending down from the drains outfalls. This may be a design detail that should be avoided. The dentates at the end of the chute remain in satisfactory condition, and the old repairs remain intact. The rocky outcrop beyond the end of the chute appeared to be stable. The ungated emergency overflow weir at the north end of the flood control structure appeared to be stable. No signs of settlement or tilting were observed. The concrete was in good condition. DWR 1261 (rev.10!09) Sheet 2 of 17 INSPECTION cr' DAM AND RESERVOIR IN .. IED STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 Observations and Comments Outlet Seepage Instr. The low level outlet was not accessible due to an operational incident that is under review by an independentconsu?ant The Palermo Tunnel outlet was inspected by the FERC Part 12 members while I inspected the House instrument panel. The outlet and tunnel were found to be in satisfactory condition. The House instrument panel is in need of repairs, but may be abandoned instead. The seepage remains very low for such a large dam. The seepage within the galleries was within the normal range. The total flow at the sump level was an estimated 30 gpm. I did not inspect the embankment toe weir. The long standing seepage area at mid?level on the left side ofthe embankment appeared to be dry. Minor, clear seepage was coming from the tubing bundle at House T, as it has in the past. The usual seepage at the S?Block tubing bundle was normal and appeared to be clear. Seepage at the saddle dams is discussed above. A Dam Safety Surveillance and Monitoring Plan was published by 08M in December 2008. Surveillance and Monitoring Report No. 13 was published in June 2008 and contains data thru December 2008. Hydraulic ptezometers: Of the 58 hydraulic piezometers installed during construction, only 5 are thought to be functional. These are read weekly. The data thru December 2008 remains within the normal range. 08M has discussed the idea of abandoning these instruments. Embankment settlement and horizontal movement: The movement data appears to be consistent with historical trends, and indicates a stable dam. Extensometers and joint monitoring: No longer read. The instrument program appears adequate in scope and coverage at this time. 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 1281 (rev. 10mg) Sheet 3 of 17 INSPECTION ur' DAM AND RESERVOIR IN .rlED STATUS Name ofDam Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 1. The along the slope can be seen in this View looking towards the right abutment. 2. This is a View of the slope from a point near the right abutment. Access paths are visible on the slope. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR1261{rev.10l09) Sheet 4 of 17 INSPECTION I. x' DAM AND RESERVOIR IN AIED STATUS Name ofDam Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 .. - 2137-4 3] at 4. This View shows the crest as seen from the left abutment. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR 1261 (rev. 10109) Sheet 5 of 17 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 5. The brush along the upstream left groin will be cleared. The rock shell and bench remain in satisfactory condition. 234.. We} 6. This is another View of the upstream bench. The small trees will be removed. Oroville Darn, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR1261 (rev.10!09) Sheet of INSPECTION DAM AND RESERVOIR IN .. IED STATUS Name ofDam Dam No. 1?48 Date of Inspection 8/25 thru 8/27 2009 7. Buildup of deposits such as this should be removed, and the utility lines should be restored. Oroville Dam, No. 1?48 Butte County 8/25 thru 8/27 2009 Sheet 7 of 17 INSPECTION DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 8. These electrical boxes in the right gallery caught ?re. The utility system in the gallery should be reviewed and upgraded as needed. 9. The crest and upstream slope of the Bidwell Bar Canyon Saddle Dam south embankment are shown. The rock slope remains in good condition. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR1261(rev.10109) Sheet 8 of 17 DAM AND RESERVOIR IN STATUS Name of Dam Oroville Darn No. 1-43 Date of Inspection 8/25 thru 8/27 2009 10. The slope of the Bidwell Bar Canyon Saddle Dam south embankment is shown. The rock slope remains in good condition. DWR 1261 (rev. 10mg) Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 Sheet 9 of 17 INSPECTION pr" DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1?48 Date of Inspection 8/25 thru 8/27 2009 . 11. View of Bidwel] Bar Canyon Saddle Dam west embankment. The trees and brush at the toe that will be removed to expose the drain line. 12. The upstream side of Bidwell Bar Canyon Saddle Dam west embankment is shown. The embankment appeared to be stable and the exposed rock was sound. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 Sheet 10 of 17 INSPECTION er' DAM AND RESERVOIR IN STATUS Name of Dam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 14. The slope of Parish Camp Saddle Dam appeared to be stable, and the rock was in good condition. Small rills have developed at the groins. These should be repaired as time permits. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR1261 (rev.10l09) Sheet i of INSPECTION ur? DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 1.11,: 15. The outlet control structure appeared to be in satisfactory condition. Gate 7 was open for use by a contractor preparing to make minor concrete repairs along the spillway chute. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 Sheet 12 of 17 INSPECTION DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 16. The ?ood control outlet hoist equipment appeared to be well maintained. Nothing unusual was observed during a cursory review of the hoist cables and diums. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 DWR 1261 (rev. 10/09) Sheet 13 of 17 INSPECTIONLE DAM AND RESERVOIR IN CERT ..-IED STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 17. The ?ood control outlet observation deck appeared to be in satisfactory condition. The bridge bents at either end of the deck do not appear to have spalled since the last inspection based on the intact orange paint shown in the background. Also see photograph 16. The trunnion beams and anchor tendons appeared to be unchanged. The Field Of?ce should continue to clear the bird droppings and other detritus from the trunnions. 18. This is a close up View of the left bridge bent shown in photograph 15. Monitoring paint is Visible along a diagonal crack that appeared to be unchanged. The crack has been stable for many years. Oroville Dam, No. 1?48 Butte County 8/25 thru 8/27 2009 Sheet 14 of 17 INSPECTION br? DAM AND RESERVOIR IN STATUS Name ofDam Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 19. This View shows a typical ?ood control outlet gate. The buildup of detritus along the bottom of the gates should be removed. All of the gates appeared to be in satisfactory condition. The gate seal system has been rehabilitated at three of the eight gates. One or two will be completed each year and time and reservoir conditions permit. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 Sheet 15 of 17 INSPECTION Ln- DAM AND RESERVOIR IN n?lED STATUS Name of Dam Oroville Dam No. 1?48 Date of Inspection 8/25 thru 8/27 2009 20. This View shows the ?ood control outlet chute as seen from the upper deck. The walls and chute appeared to be stable and in satisfactory condition. Minor repairs along the chute ?oor will be completed this year. 21. The lower flood control outlet chute is shown. Not the markings for the upcoming chute repairs. Oroville Dam, No. 1?48 Butte County 8/25 thru 8/27 2009 DWR1261(rev.10f09) Sheet 16 of 17 INSPECTION :Lr DAM AND RESERVOIR IN .. -IED STATUS Name of Darn Oroville Dam No. 1-48 Date of Inspection 8/25 thru 8/27 2009 22. This is a typical crack pattern at a wall drain along the spillway chute. This may be a design detail to avoid in the future. Other vertical cracks were also noted along the walls. None of the cracks that were observed closely appeared to be open or offset laterally. 23. The end of the spillway chute is shown. Minor concrete scouring is Visible. The drains were dry, and the rock beyond the chute appeared to be stable. Oroville Dam, No. 1-48 Butte County 8/25 thru 8/27 2009 Sheet 17 of 17