Barnard Construction Co. began preliminary foundation work in June 2009 for a project to add 117 feet to the 220-foot-tall San Vicente Dam in Southern California, the world’s largest dam heightening project using roller-compacted concrete.
With a bid of $23.7 million, Barnard, of Bozeman, Mont., was chosen by owner San Diego County Water Authority from among four competitors in a rebidding of the contract for foundation preparatory work. (HydroWorld 4/6/09) SDCWA soon is to invite pre-qualification to actually perform the roller-compacted concrete construction work.
The $568 million San Vicente Dam Raise Project would more than double the storage capacity of San Vicente Reservoir. The upgrade is to enable the reservoir to store an additional 152,000 acre-feet of water, bringing its total capacity to 242,000 acre-feet.
The entire project, scheduled for completion in late 2012, is the largest dam heightening in the world using roller-compacted concrete and the tallest dam heightening in the United States, the authority said. Refilling the reservoir after construction is to take another two to five years.
A groundbreaking ceremony convened July 9, featuring remarks by Secretary Mike Chrisman of the California Natural Resources Agency, San Diego Mayor Jerry Sanders, and SDCDA’s Chairman Claude Lewis and General Manager Maureen Stapleton.
Contract covers foundation work, cofferdam, tunnel
The construction phase covered by the new contract is to include excavating the dam’s foundation and preparing the site for construction. The work entails drilling, blasting, excavating, and cleaning the foundations for the main dam and a smaller saddle dam, selective concrete demolition, installation of a 111-foot-tall cofferdam, construction of a 13-foot-diameter tunnel through the existing dam, and demolition of a marina. The first phase of work is to be complete in 2010.
Joining Barnard as subcontractors and suppliers are Penhall of San Diego, selective concrete demolition; American Hydro of Fenton, Mo., hydro-demolition; Associated Underwater Services of Spokane, Wash., diving; Fox Fire of San Clemente, Calif., tunnel; Northwest Pipe of Scammons, Kan., steel pipe; and Midwest Steel Industries, Belgrade Mont., steel cofferdam.
A joint venture of Parsons and Black & Veatch received a contract in 2008 for design review and construction management. MWH Global Inc. performed design and engineering services under a contract awarded in 2006.
Pre-qualification seen for RCC work
SDCWA plans to issue additional solicitations, most notably for construction to begin in 2010 of the roller-compacted-concrete dam and appurtenant facilities valued at $260 million to $300 million. An invitation for pre-qualification for that work was to have been issued in mid-July but has been delayed, the SDCWA engineering department said.
SDCWA operates an Internet site with information on upcoming solicitations, www.sdcwa.org/opps/contracts.phtml.
The work is a major component of the water authority’s $1.5 billion Emergency Storage Project. When complete, the project will provide up to six months of locally stored water if a natural disaster cuts off the region’s imported water supplies. In addition to emergency storage, the enlarged San Vicente Reservoir is to hold 100,000 acre-feet of carryover storage, which would allow the water authority to store water during wet periods for use during subsequent dry years.
Although San Vicente has no hydropower, SDCWA holds a preliminary permit from the Federal Energy Regulatory Commission to study developing a 570-MW San Vicente pumped-storage project (No. 12747) using San Vicente Reservoir as its lower reservoir.