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Released On: December 09, 2003
The project is under Reclamation's Yakima River Basin Water Storage Feasibility Study that was authorized by Congress in February 2003.
Field investigations require Reclamation to drill exploratory holes at the potential Black Rock dam site, located about 30 miles east of Yakima, Washington.
This work builds on earlier field investigations conducted by Washington Infrastructure Services, Inc. of Bellevue, Washington, on behalf of Benton County in 2002. The present field work that started on December 4, will evaluate an alternate dam alignment that was identified in the WIS report.
This is the first of several phases of investigation planned for the alternate alignment; Reclamation will drill a series of four to six holes to determine the top of bedrock. The 6-inch diameter holes will be drilled to approximate depths of 50 to 75 ft deep with provision to extend one of the holes to 200 ft, if needed.
Subsequent phases of the investigation will include geophysical surveys along the alternate alignment to help select a site for drilling of a deeper 400 foot exploration hole in January, 2004, that will explore a foundation for the proposed dam.
"Once the 400 foot hole is drilled, we will examine core samples obtained that will be used to evaluate the geologic character and engineering properties of the foundation material," said Norbert Ries, Reclamation Planning Officer.
In February, 2004, a second companion hole will then be drilled to perform detailed ground-water tests to evaluate the permeability of the foundation materials and the potential for leakage between individual aquifers.
"Data collected from these tests will be used to evaluate the ability of the proposed dam to store water and to assess potential seepage losses from the reservoir," Ries said.
With a potential capacity of 1.7 million acre-feet, the potential reservoir would more than double existing water storage in the Yakima River Basin. Water would be drawn from the Columbia River near Priest Rapids Dam. Reclamation will compare the proposed Black Rock Dam and Reservoir with other options during a feasibility study of storage potentials in the Yakima River basin.
DOI | Recreation.gov | USA.gov
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