Safety of Dams Program |
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Overview | Idaho | Montana | Oregon | Washington | Wyoming | Dams & Projects The Bureau of Reclamation oversees the operation of more than 70 dams in the Pacific Northwest. The Safety of Dams program was created in response to the failure of Teton Dam in 1976. Since then, Reclamation has embarked on a rigorous review of every major dam in the region. Each major structure is periodically reviewed for resistance to seismic stability, overtopping, internal stability, and physical deterioration. Long-term stability of the dam is our goal in order to save lives, protect property, and insure the physical integrity of what we build or maintain. Comprehensive Facility Reviews (CFRs) are performed every six years, and include participation from the Area Office, Regional Office, and Technical Service Center (TSC). CFRs include not only a detailed on site examination, but they also look at changes in the state of the art, the loading conditions on the dam, downstream population, and an evaluation of the risks. Periodic Facility Review (PFRs) are performed every six years by the Area and Regional Offices, midway between comprehensive facility reviews and involves a detailed on site examination of the structures. Annual site inspections are conducted by the responsible Area Office in those years in which there is no CFRs or PFRs. Emergency Action Plans (EAPs) have been developed and are annually updated for all high and significant hazard dams. Tabletop and functional exercises are performed for each dam every three and six years, respectively. Tabletop exercises entail an informal discussion of actions to be taken in an example emergency situation. Functional exercises practice a timed, emergency response to a simulated incident. |
Idaho | In Idaho, Safety of Dams modifications have been completed at Island Park , Deer Flat, Soldiers Meadow, Reservoir "A", and Deadwood dams. Modifications were performed at Deer Flat Dam embankments near Nampa on the Boise Project from 1991 to 1993 for $20 million. Modifications consisted of construction of a filter and drain system in a deep interceptor trench and embankment berms along the downstream toe of the Upper and Lower Embankments. A soil-cement layer was also placed on the upstream face of the Lower Embankment as an erosion barrier. An emergency was declared on May 13, 2005 due to seepage and piping concerns at the Caldwell Canal outlet works conduit. An emergency berm was constructed around the Caldwell Canal gate structure and surrounding embankment. Monitoring continues as engineers and geologist evaluate alternatives for a permanent solution. Three other outlet works conduits are being evaluated as well to determine if similar concerns exist at these structures. Construction is scheduled for the fall of 2007. Modifications at Soldiers Meadow Dam on the Lewiston Orchards Project were completed in 1986 at a cost of $1.7 million. Construction included upgrading the spillway crest and unlined channel, and seepage control measures on the embankment. |
Oregon | In Oregon, Safety of Dams modifications have been completed at Ochoco, Cold Springs, Crane Prairie, Fish Lake , Wasco, and McKay, Wickiup and Scoggins dams. Dam safety investigations are continuing at Arthur R. Bowman Dam. Ochoco Dam, part of the Crooked River Project, was modified between 1994 and 1997 for a total cost of $35 million. Construction in 1994 and 1995 focused on embankment modifications, while work in 1996 and 1997 centered on modifications to the spillway and the addition of a spillway stilling basin. Safety of Dams modifications at Cold Springs Dam on the Umatilla Project were performed during 1995 and 1996 for about $6.6 million. Modifications included removal and replacement of low strength materials in the foundation, installation of a filter/drainage system and stability berm along the downstream toe of the dam. The concrete spillway was removed and an enlarged RCC (roller compacted concrete) spillway constructed. Minor modifications to the spillway at Crane Prairie Dam on the Deschutes Project were performed in 1992 at a cost of about $87,000. Purpose of the modifications was to upgrade the ability of the spillway to safely pass large floods. Modifications included raising the right spillway wall about five feet to prevent spillway discharges from potentially impacting the embankment. Modifications at Fish Lake Dam on the Rogue River Project were performed in 1996 for $1.6 million. An auxiliary spillway was constructed and a rock buttress was added on the downstream face of the dam. Investigations have identified a hydrologic safety deficiency in passing major flood events without overtopping the embankment at Arthur R. Bowman Dam, which impounds Prineville Reservoir, on the Crooked River Project. The project has been re-evaluated in recent years by applying new hydrologic techniques and a risk-based approach to overtopping. Modifications are scheduled for late 2007. |
Montana | Safety of Dams modifications were performed at Como Dam near Darby on the Bitter Root Project from 1992 through 1995 at a cost of about $12.5 million. As part of this project, the State of Montana and local interests provided over $400,000 to raise the dam and reservoir by 3.3 feet to create an additional 3,000 acre-feet of storage for enhancement of instream flows in the Bitterroot River . Modifications included the construction of a deep seepage interceptor trench along the downstream toe of the dam. A sand and gravel filter/drain system was installed in the trench and an embankment berm constructed above the drain system. Major portions of the embankment were removed and reconstructed to a higher crest elevation. The concrete spillway structure was rebuilt with a new overflow ogee crest and a parapet wall added to the crest of the dam. The gatehouse and catwalk were replaced and new gate operators installed. |
Washington |
Safety of Dams projects in Washington include modifications at Bumping Lake Dam, Salmon Lake Dam , the breaching of Clear Creek Dam, and Keechelus Dam. |
Wyoming |
The Pacific Northwest Region includes the portion of Wyoming within the Snake River drainage including Jackson Lake and Grassy Lake Dams. Both dams have been the subject of Safety of Dams projects. |
Last Update: October 18, 2006 1:11 PM
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