Corps to provide update on cofferdam leak at Auxiliary Spillway construction site

Published Jan. 20, 2016

SACRAMENTO, Calif. – The U.S. Army Corps of Engineers (USACE) and its contractors are responding to a leak in the temporary construction cofferdam at the Folsom Dam auxiliary spillway project site in Folsom, California. 

At approximately 4:30 a.m. workers for Kiewit, the prime contractor for Phase IV of the USACE project, noticed water seepage through a temporary earthen cofferdam and into the construction site.  The cofferdam is a temporary barrier that allows the contractor to perform excavation in the dry.

To ensure public safety, the U.S. Bureau of Reclamation (USBR) immediately responded to the leak by closing the bulkhead gates to hold back water from the reservoir in the event of a cofferdam failure.  

The contractor has worked throughout the day to stabilize and reinforce the cofferdam by adding rockfill material on the downstream face. The approach channel work area has been evacuated to ensure worker safety on the site. 

Once the cofferdam is stabilized and they can proceed safely, Kiewit will remove their equipment from the approach channel to mitigate any potential environmental concerns associated with fuel in the construction site.

Kiewit had always planned to allow water against the control structure in mid-February by pumping water over the temporary cofferdam to equalize water on both sides of the structure prior to finishing excavation in the wet. Once the immediate situations have been addressed, Kiewit, USACE and USBR will update plans for how to proceed with remaining construction work.  

Representatives from USACE will provide an update to the media regarding the cofferdam leak at the Folsom Dam auxiliary spillway construction site at 4 p.m. at construction gate 3 on Folsom Lake Crossing.  Photos will be made available but media will not be allowed access to the site for safety reasons.

The auxiliary spillway project is being constructed under the Corps’ Folsom Dam Modification Project, also called the Joint Federal Project, to implement dam safety and flood risk reduction features at Folsom Dam and associated facilities to help prevent catastrophic flooding in the Sacramento region. The auxiliary spillway is on track for completion in October 2017.

Tyler Stalker

Release no. 16-003