U.S. plans spillway bidding as part of 198.72-MW Folsom Dam upgrade

The Bureau of Reclamation said it plans to request proposals to construct a new auxiliary spillway and wing dams at California’s 198.72-MW Folsom Dam as part of a plan to increase flood protection for Sacramento and to improve dam safety.

BuRec and other agencies recommended increasing the height of the dam 3.5 feet and building the auxiliary spillway as the preferred alternative in a final environmental impact statement released at the end of March. (HNN 7/12/06)

BuRec, the Corps of Engineers, state agencies, and a local agency studied five scenarios to address flood damage reduction, dam safety, and security issues. The agencies found that none of the other alternatives would achieve the project’s purpose and need.

Spillway construction bidding seen in July

BuRec issued a pre-solicitation notice April 16, identifying July 9 as a tentative due date for proposals to construct the new auxiliary spillway and wing dams. It estimated the work would cost between $25 million and $50 million.

Work would include: excavation of more than 600,000 cubic yards of rock and other material for the auxiliary spillway; rock bolting and shotcrete on excavated rock slopes; design and construction of construction access roads; placement of drainage filter and excavated materials on earthen dams; resurfacing of roads; and controlled blasting of rock near critical structures. The contractor also would be responsible for partial dam removal and reconstruction to avoid risk to the downstream public.

The solicitation is to be available from the Federal Business Opportunities Internet site at www.fbo.gov. No paper copy will be distributed. Contractors must register in the Central Contractor Registration database at www.ccr.gov. E-mail questions about the solicitation to Diva Heitz, Bureau of Reclamation, Mid-Pacific Regional Office, 2800 Cottage Way, Room E-1815, Sacramento, CA 95825; E-mail: dheitz@mp.usbr.gov.

EIS stems from 2006 revision of dam upgrade plan

The environmental impact statement is based on a revised plan for Folsom, issued in 2006, that estimated it would cost $1.357 billion to add the auxiliary spillway and possibly increase the height of the dam, with completion by 2014.

A previous plan, costing $2 billion, included building an auxiliary spillway, enlarging and adding outlets, and raising the height of the dam seven feet, with completion by 2023.

BuRec was lead federal agency for the EIS, with the Corps serving as a cooperating agency. Other partners included the California Department of Water Resources, California Reclamation Board, and Sacramento Area Flood Control Agency.

The preferred alternative includes construction to increase dam height 3.5 feet and replacement of three emergency spillway gates to reduce flood damage. It also includes construction of an auxiliary spillway and control structure with six submerged tainter gates, concrete-lined chute, stilling basin, and approach channel.

It also calls for jet-grouting of the Mormon Island Auxiliary Dam foundation for seismic stability; and toe drains and filters at the Left and Right Wing dams, Mormon Island Auxiliary Dam, and Dikes 4, 5, and 6 to address static risks. The plan includes security upgrades at Folsom Dam and related structures.

The EIS addresses: flood damage reduction measures that would be implemented by the Corps; dam safety and security issues that would be implemented by BuRec; and the Joint Federal Project auxiliary spillway that would be implemented by both agencies.

Although the document is considered final, the government said it would accept comments on the statement through April, as required by the National Environmental Policy Act. Following the comment period, the agencies will complete records of decision to implement the work.

The document is available on the Internet at www.usbr.gov/mp/nepa/nepa_projdetails.cfm?Project_ID=1808. Comments may be submitted by April 30 to Shawn Oliver, Bureau of Reclamation, 7794 Folsom Dam Road, Folsom, CA 95630, E-mail: soliver@mp.usbr.gov, and Becky Victorine, Corps of Engineers, 1325 J St., Sacramento, CA 95814; E-mail: rebecca.a.victorine@usace.army.mil.

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