After heavy rains, a small “leak” was observed through an approximately 10-foot by 10-foot opening in the shoreline of the lake. Over the weekend, the entire lake drained through a large sink on the lake bottom. The water reappeared in Lewis Spring, about four miles north of the lake site.

Shannon & Wilson was hired by the homeowners association to determine the cause of the sink and to develop methods for repair. Research indicated that the lake had been placed in a known karst area and had a history of leakage. Our services included:

• Evaluating the safety of the dam and reservoir
• Subsurface exploration to identify and determine the extent of the voids or solution channels, including a geophysical survey and exploratory borings
• Development of a repair plan

Our subsurface investigation revealed that the wave action in the lake may have been eroding the liner and that recent installation of a sewer had further disturbed the liner. This loss of liner allowed seepage through the lake bottom aggravating the ground loss through the sink.

Shannon & Wilson designed and oversaw the implementation of a grouting and lining program to plug the sinkholes. We also made recommendations for repairing erosion along the east bank of the lake, which included flattening the slope and adding a clay liner and riprap.