Dworshak Dam Remedial Foundation Grouting Lewiston, Idaho Back to Project List High Mobility Grouting The hydraulic head ranged from 150 feet at monolith 15, to 350 feet at monolith 19. Project Overview: Dworshak Dam, located on the North Fork of the Clearwater River, was experiencing total seepage flows exceeding 5000 gallons per minute. Dworshak is the highest straight axis dam in the Western Hemisphere, and the third highest dam in the United States. Concerned that the increasing seepage volumes indicated the possibility of bedrock erosion occurring along fractures downstream of drains, the US Army Corps of Engineers initiated a remedial grouting program. Layne GeoConstruction performed the drilling and grouting work in confined spaces of the galleries, 6 feet wide and 8 feet high, sloping steeply downward from monoliths 14 to 18. In total, 162 grout holes were drilled, with a total drilling footage of 19,848 feet.     Value of Work Performed: $5,800,000 Project Duration: 6 months Project Completion Date: March 1998 Project Reference: Project Owner U. S. Army Corps. of Engineers