The San Francisco Public Utilities Commission is seeking a contractor to replace the 85-year-old Calaveras Dam near Fremont and Sunol in the East Bay for a project estimated to cost $434 million.

Photo: Courtesy of SFPUC

The Calaveras Dam normally supplies nearly half the water to the Bay Area.

Notice went out on Jan. 31, with a pre-bid meeting scheduled for Feb. 15 and contract award at the end of March. Construction, estimated to cost between $250 million to $300 million, is set to start in the summer.

Prequalified prime contractors eligible to bid on the project include Dragados USA, New York; Barnard Construction Co., Bozeman, Mont.; Kiewit Infrastructure Group, Fairfield, Calif.; Sukut Construction Inc., Santa Ana, Calif., and Impregilo S.p.A. of Milan, the owner says.

The project is a vital part of the $4.6-billion Hetch Hetchy Water System Improvement Program to upgrade aging pipelines, tunnels and reservoirs for 2.5 million customers in the San Francisco area. Scaled back to 30% capacity in 2001 due to seismic concerns, Calaveras Dam’s normal capacity is 96,850 acre-ft , or 31 billion gallons, of water, representing nearly half the water storage capacity in the Bay Area.

The new 210-ft-high, earth- and rock-fill dam will be built adjacent to the old facility with a new concrete spillway and intake tower. It will have a crest length of 1,210 ft, a crest thickness of 80 ft and a base thickness of 1,180 ft. The new dam will be able to withstand a 7.25-magnitude earthquake.