The Gem State Hydropower Project

by Lee DeHeer, CH2M Hill, Bellevue, WA, USA,
Miles Bubenik, CH2M Hill, Bellevue, WA, USA,
Steve Harrison, CH2M Hill, Bellevue, WA, USA,
Mark Gendron, CH2M Hill, Bellevue, WA, USA,

Document Type: Proceeding Paper

Part of: Water Power '87


The Gem State Hydroelectric Project is located on the Snake River about 5 miles southwest of the City of Idaho Falls, Idaho. The project consists of a 40-foot high, 900-foot-long earth and rockfill dam; 4 miles of earth dikes; a 23. 4-megawatt powerhouse; a 1-mile transmission line, and two irrigation intake structures. The maximum recorded flow in the Snake River at the site is 70,000 cfs, which occurred subsequent to the failure of the Teton Dam in 1976. The project is designed to pass the Probable Maximum Flood of 140,000 cfs. The spillway is designed to use radial gates from Chief Joseph Dam that are being modified to provide adequate spillway capacity. The powerhouse, spillway, and dam will form a continuous barrier across the river. The foundation consists of a series of basalt flows with interbeds of silt and ash. During the design phase, an erosion channel was discovered in the river, which required special design considerations.

Subject Headings: Hydro power | Dam failures | High-rise buildings | Power plants | Hydraulic design | Earthfill dams | Power transmission lines | Urban areas | Idaho | United States

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