The Joint Federal project, which involves construction of an auxiliary spillway, represents an unprecedented partnership among USBR, the US Army Corps of Engineers (USACE), the Central Valley Flood Protection Board, and the Sacramento Area Flood Control Agency. When completed, the project will address the hydrologic risk to Folsom Dam identified through USBR’s Safety of Dams evaluation program. Hydrologic risk refers to possible overtopping of the dams and dikes during an extreme storm event. The project also achieves USACE’s objective of increasing flood control at Folsom.
The initiative consists of a water-side approach channel, a control structure with six submerged tainter gates, a concrete-lined spillway chute about 914m long, and a stilling basin which acts as an energy dissipation structure prior to discharges converging with the American river below the main concrete dam. The project will be constructed in three successive phases by USBR and USACE.
The Phase II contract with Oregon Mt. Construction Company includes additional spillway excavation, construction of a stilling basin coffer dam, relocation of a 42-inch water supply pipeline, and ancillary access roads. Work will begin in mid-winter 2008-2009 and will be completed in summer 2010. Phase III construction by USACE will follow shortly thereafter, and the project is expected to be completed by 2015.
In addition to the Joint Federal Project, USBR will complete additional dam safety work on Dikes 4, 5, and 6, and the Mormon Island Auxiliary Dam. Additional information on the project is available on USBR’s website at http://www.usbr.gov/mp/jfp/index.html.
