Corps to place water against auxiliary spillway control structure

Published Jan. 26, 2016

SACRAMENTO, Calif. – The U.S. Army Corps of Engineers and its contractor Kiewit Co. are moving forward with the next milestone at the Folsom Dam auxiliary spillway project in Folsom, California, by placing water against the auxiliary spillway control structure.

The process, known as impoundment, is expected to begin Wednesday morning and will continue until lake water reaches equal elevation on both sides of the temporary construction cofferdam, which is expected to take about 24 hours.

Eight pumps will push water from the reservoir into the approach channel and against the control structure through two 24-inch pipes, each capable of pumping up to 16,000 gallons per minute.

This first fill against the auxiliary spillway control structure is a significant milestone for the project, indicating the auxiliary spillway is much closer to becoming operational.

Kiewit reinforced the temporary construction cofferdam last week following the discovery of a leak that partially filled the approach channel construction area. Stabilizing the leak allowed crews to safely remove construction machinery and materials that were abandoned upon discovery of increased seepage. The Corps and Kiewit continue to constantly monitor the temporary construction cofferdam to ensure personnel safety.

The temporary construction cofferdam was put in place to help conduct construction activities under dry conditions rather than in-the-wet. Removal of the temporary structure was expected to occur by Feb. 8, 2016; however, it was decided to begin the impoundment process and remove it sooner.

The auxiliary spillway project, or Joint Federal Project, is being constructed in partnership with the U.S. Bureau of Reclamation under the Corps’ Folsom Dam Modification 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, within budget, in October 2017. 

Rick Brown

Release no. 16-004