Langley Gulch Power Plant Water Supply Development
For Idaho Power, Wenck developed an alluvial water supply to provide industrial cooling water for a gas-fired peak power generation plant. The wellfield is located approximately 45 miles northwest of Boise, Idaho, along the Snake River. Initially Idaho Power had obtained surface water rights on the Snake River for industrial purposes. Given the potential costs and difficulty with permitting and maintaining a surface water intake, Wenck proposed and completed a shoreline alternative investigation to determine the feasibility of the alluvial aquifer for cooling water supply.
Wenck supervised the drilling, completion, development, and aquifer testing of a 6-inch test well completed in the alluvial aquifer. The site was underlain by permeable river deposited sand and gravel, capable of yielding significant quantities of groundwater to individual alluvial wells. Wenck recommended and Idaho Power consented to drill a production sized test well to evaluate the yield potential of individual production wells, and to obtain additional hydrogeologic data for wellfield design.
Wenck supervised additional drilling, completion, development, and aquifer testing of a 16-inch diameter test well. Stepped rate testing of the well indicated it would yield up to 865 gpm. A constant rate test was conducted at a discharge rate of 620 gpm for seven days. Based on the well’s hydrologic connection to the Snake River and lower costs, Wenck recommended the completion of several additional alluvial production wells to meet Idaho Power’s cooling water demands.
Five additional 12-inch diameter alluvial production wells were constructed. The alluvial wellfield consists of six wells that are completed to depths ranging from 50 to 71 feet. Individually, the wells are capable of yielding between 175 and 620 gpm. Collectively, the wells were capable of providing the requisite water for the project.
Major Project Features:
- Well Siting and Design
- Alluvial Groundwater Supply
- Lithologic Logging and Contract Administration
- Aquifer Testing
- Water Quality Sampling
- Alluvial Wellfield Design
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