Lake Townsend is the primary water supply for Greensboro. The spillway concrete was suffering severe deterioration from alkali silica reaction (ASR) and needed to be rehabilitated or replaced. Additionally, the dam was found to have inadequate spillway capacity to pass the spillway design flood. Temporary repairs were initially made, but Schnabel’s evaluation of alternatives determined that replacement of spillway and downstream embankments was the preferred option.
The replacement spillway is a 300-foot-wide labyrinth weir, with a total weir length of more than 1,000 feet. The new embankments are armored with articulating concrete blocks to protect them from overtopping during extreme flood events. The water supply intake and pump station was also replaced.
Schnabel performed a dam breach analysis and prepared an emergency action plan (EAP) for the construction and post-construction phases. We obtained the necessary permits, provided construction contract administration and resident engineering services, and quality assurance testing in an on-site lab. This project received the ACEC 2013 Engineering Excellence Grand Award, the 2013 Engineering Excellence Competition National Recognition Award, and the 2012 ASDSO National Rehabilitation Project of the Year Award.