Lake Grady Dam History and Rehabilitation

Abstract Only - The Lake Grady Dam (also locally known as the Shadow Run Dam) was constructed in 1969 to provide waterfront residential property and a recreational lake for the Shadowrun Subdivision. The subdivision is located in southwestern Hillsborough County, Florida (near Tampa). The dam was originally built using earthen materials across Bell Creek with a corrugated metal pipe spillway and outfall structure.
The dam is approximately 1200 feet long and about 20 feet high from the downstream toe elevation. After the dam was constructed, an asphalt paved roadway surface with curbs, gutters and catch basins was built along the dam crest as part of the subdivision's roadway
The dam apparently performed satisfactorily from its original filling until 1983 when one of the six foot diameter corrugated metal spillway outfall pipes developed a hole and dam materials began raveling into the pipe hole, forming a long sinkhole like feature in the upstream slope over the outfall pipes. Emergency actions consisted of lowering the lake level and filling the void in the upstream slope.