BUILDING ON KARST - A BRIEF HISTORY OF GATHRIGHT DAM (Invited Presentation)

Gathright Dam is a 257 ft high rock-fill embankment dam with an impervious earth core located on the Jackson River in the western central portion of Virginia, 14 mi north of the City of Covington. The dam, owned and operated by the Norfolk District of the US Army Corps of Engineers, was constructed between 1967 and 1979. The foundation and abutment bedrock consists of karst-prone sedimentary rock, which required extensive treatment of joints and solution cavities to cut off potential seepage pathways.

This presentation will cover a case history of the treatment that was completed on the embankment foundation and abutment bedrock at Gathright Dam. Treatment methods included 30-foot deep consolidation grouting and 150-foot deep curtain grouting in the foundation and both abutments. In addition to the grouting, an 800-foot long concrete membrane wall was constructed in the left abutment to isolate extensively solutioned bedrock layers.