U.S. Bureau of Reclamation crews will begin drilling and installing numerous dewatering and observation wells at Echo Dam to lower the groundwater table in the area immediately downstream of the dam to accommodate subsequent seismic retrofit work. This work to be done is part of Reclamation's Safety of Dams Program, which ensures dams are inspected for safety deficiencies and corrective actions are implemented if necessary, USBR reported.
Echo Dam is a 158-foot high zoned earthfill structure on the Weber River, located one mile upstream from the town of Echo and 42 miles southeast of Ogden, Utah. Part of the Weber River Project, Echo Dam was constructed between 1927 and 1931 to help supply supplemental irrigation water to approximately 109,000 acres of land west of the Wasatch Mountains. Echo Dam is operated by the Weber River Water Users Association.
Seismic retrofit work was identified as necessary in a completed risk-analysis and corrective action study done by Reclamation and reviewed by a board of independent consultants. Work to lower the groundwater table will facilitate the planned excavation work downstream of the dam to replace potentially liquefiable materials in the dam foundation with stronger and denser material while also reducing potential risks associated with a significant seismic event in the meantime.
Drilling at the dam is scheduled to begin in mid-August and continue through the spring of 2011. Several exploratory holes will also be drilled near the spillway and on the upstream face of the dam as part of the ongoing field investigation. The work will have no effect on the recreation at the reservoir or users of the reservoir water, USBR reported.
In other news, the Bureau of Reclamation awarded Washington-based Knight Construction & Supply Inc. a US$1.5 million contract for modifications to a wheel-mounted gate servicing chamber in the Third Powerplant at the 6,809-MW Grand Coulee hydroelectric project.
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