Prestwood Lake Dam Rehabilitation

Henry, James F.; Sams, Clay E.; ,

Prestwood Lake Dam Rehabilitation

by James F. Henry, Hayward Baker Inc, Tampa, United States,
Clay E. Sams, Hayward Baker Inc, Tampa, United States,

Document Type: Proceeding Paper

Part of: Geotechnical Practice in Dam Rehabilitation

Abstract:

The Prestwood Lake Dam located in Hartsville, South Carolina is owned by Sonoco Products Co. It originally was a wood structure built in 1895. That structure was washed out by a hurricane and in 1928 a slab and buttress concrete dam was built on top of the old dam's wood grillage. The original wood cut off walls were incorporated into the new dams structure. Seepage under the dam has been a problem. Since 1968, a number of remedial actions have been taken to correct the seepage problem. In 1977 an extensive grouting program was accomplished under the dam. Recurrent leakage led to additional grouting programs. Although grouting has been beneficial, seepage continues to occur under the dam. The dam is founded on 2.4 to 3.0 m (8 ft to 10 ft) of loose sand. The continued erosion of sand from under the structure and the possible continued deterioration of the wood cut off walls coupled with very loose foundation sands create the potential for distress to the structure. During flooding it was felt that the dam could move in a down stream direction. Construction was considered potentially hazardous to the dam so special sequences of construction were required. Eventually, the seepage problem was solved using a three pronged approach. First, angled compaction grouted anchors were constructed through the floor of the dam. These anchors achieved a rapid increase in the stability of the dam through simultaneously anchoring the dam from sliding, densifying loose sub-soils and filling voids and seepage channels under the dam.

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