Wednesday, June 01, 2011

Folsom Dam Modifications

They are proceeding along, as reported by Sacramento Press, and will eventually increase our flood protection level to 200 years from the current 100, though we really need the 500 year level, which only an Auburn Dam can provide, as we've posted previously.

An excerpt.

“Floods in 1986 and 1997, as well as a levee break in 2004, costing lives and billions in damage, contributed to Gov. Arnold Schwarzenegger declaring a state of emergency due to the threat of major flooding in northern California and San Joaquin Valley in 2006, and current work on Folsom Dam is helping alleviate that threat.

“The construction of an auxiliary spillway at the Folsom Dam will provide the Sacramento region a greater level of flood protection than it has now. More specifically, it will provide a 200-year level of protection, meaning a one-in-200 chance for flooding in any given year.

“Friday morning, 25 state and federal workers and even a few spectators gathered at the Folsom Dam for a presentation and tour of the ongoing work known as the Folsom Dam Joint Federal Project (JFP).

“The JFP is a cooperative effort between the Central Valley Flood Protection Board (CVFPB), Sacramento Area Flood Control Agency (SAFCA), Department of Water Resources (DWR), the U.S. Army Corps of Engineers and the U.S. Bureau of Reclamation.

“The $962 million project involves the construction of an auxiliary spillway consisting of a control structure, spillway chute, stilling basin and approaching channel. Beth Salyers, lead project manager on JFP for the U.S. Army Corps of Engineers, said the new control structure will operate in conjunction with existing spillway gates on Folsom Dam to manage flood flows from the Folsom Reservoir.

“The solicitation on the original modifications to the dam had been canceled in January 2006 due to funding issues. At the same time, the Bureau of Reclamation recognized that there were some dam safety issues, such as to prevent overtopping, that needed to be addressed,” said David L. Neff, the technical lead on the JFP for phase three from the U.S. Army Corps of Engineers. “That served as the impetus to combine the two single-purpose projects into one.”

“Salyers said the JFP consisted of five phases. The first two phases included extensive excavation at the site, which was recently completed by the U.S. Bureau of Reclamation. Phase three is the construction of the control structure, and phase four is construction of the chute and stilling basin. Phase five involves construction of the approach channel. The project is currently in phase three.

“The new control structure will be similar to the current dam, but built with the gates built 50 feet lower than the existing gates.

“What this means is that now we don’t have to wait for the reservoir to fill up in order to release water. Water can be released sooner to provide more efficient use of the storage space and, consequently, free up capacity in the reservoir,” Neff said.”