Holes were discovered by the maintenance staff of Dominion Energy on the downstream slope of the original embankment of the earthen dam at Lake Murray. The holes were located in an area where wooden trestles were utilized during the original construction and due to decay of the timber and water erosion, holes have formed. The dam was built with shallow rock drainage tunnels according to a report filed by the Federal Energy Regulatory Commission.
Mr. Ray Ammarell, Manager of the Dam Safety and Civil Engineering at FERC plans a follow-up with ground penetrating radar to determine if any anomalies have occurred in the surrounding area.
The holes were discovered in February of this year and there is no immediate concerns that the dam is unsafe.
Dreher Shoals dam was built in the 1930s and was one of the largest earthen dams in the world at that time. A ‘back-up’ dam was built in 2005 at a cost of $275 million to protect the integrity of the lake if the earth dam fails.
Wooden trestles can be seen in this construction photo of the Dreher Shoals dam