A temporary cofferdam that kept crews and construction areas dry during the construction of a new spillway at Folsom Dam began leaking Wednesday, forcing crews to evacuate.
“It was a construction incident,” said Bob Kidd, spokesman for the U.S. Army Corps of Engineers. Corps officials said there was no risk to life downstream.
Late Wednesday afternoon, Tyler Stalker, a spokesman for the Corps, said workers had stabilized the cofferdam and would have all their equipment moved out Wednesday night. The work using the cofferdam was to be completed by Feb. 8 and can be done under wet conditions that don’t require the cofferdam.
The $900 million Folsom Dam Auxiliary Spillway project is an effort between the U.S. Army Corps of Engineers and the federal Bureau of Reclamation.
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The project to build an auxiliary spillway will add to the functions of the main Folsom Dam and allow water to be released earlier and more safely from Folsom Lake during periods of high water.
The spillway will include a channel that will funnel the water from the lake into the spillway and six submerged gates that will be controlled in coordination with the gates on the main dam.
The auxiliary spillway is scheduled to be completed in late 2017.
The earthen cofferdam, built on the lake side of the dam, is a temporary structure to allow construction for the spillway.
Katie Charan, Army Corps of Engineers project manager for the auxiliary spillway, said that at about 4:30 a.m. Wednesday construction crews noticed what she called a small seepage leak. Officials made sure that all bulkhead gates on the dam were in the down position so no water would stream into the American River.
Construction crews were evacuated and officials began monitoring. Later, drivers worked to stop the leak Wednesday with dump truck loads of dirt and rock.
Asked if the rising lake from recent precipitation might have caused the leak, Charan said that she could not say that only the rain caused the seepage. She said no equipment was swamped.