Bureau of Reclamation crews begin test drilling this week to evaluate the seismic stability of 1.425-MW Wanship Dam, a 175-foot-tall, 2,015-foot-long earthfill dam that is part of the 5.7-MW Weber Basin project in Utah.
The field exploration program is to collect information for risk assessments and to determine performance parameters of the dam. BuRec is working in cooperation with Weber Basin Water Conservancy District, which has operated and maintained the project since 1968.
Drill crews and geologists are to drill several test holes in the zoned earthfill dam. Investigators will evaluate the potential for liquefaction of foundation alluvial materials in the event an earthquake that could compromise the dam’s integrity. BuRec said the work would take several weeks.
Additional explorations could be required, depending on the results of the initial investigations of the foundation, which consists of clay, silt, sand, and gravel.
Wanship Dam, 1.5 miles south of Wanship on the Weber River, impounds Rockport Lake, a 62,120-acre-foot reservoir. The dam provides storage for irrigation water and power generation. Wanship power plant has a single 1.425-MW turbine-generator. The Weber Basin project has a second development, 4.275-MW Gateway power plant.
The work is being conducted under the authority of the Safety of Dams Act of 1978, which ensures BuRec dams receive periodic examinations and evaluations for early detection of potential dam safety problems.