The San Francisco Public Utilities Commission last week gave final approval for replacing the 85-year-old Calaveras Dam near Fremont and Sunol in the East Bay.

According to SFPUC spokeswoman Maureen Barry, the new $434-million dam project started bid advertising Jan. 31 with a pre-bid scheduled for Feb. 15 and contract award at the end of March. Construction is scheduled to start in the summer.

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

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 San Francisco, Alameda, Santa Clara and San Mateo counties.

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 base thickness of 1,180 ft, and crest thickness of 80 ft. The new dam will be able to withstand a 7.25 earthquake.

The SFPUC last week also awarded a contract to Kiewit Infrastructure West for the structural retrofit of the Harry Tracy Water Treatment plant at the Crystal Springs Reservoir in San Mateo County. The $174 million project, located 1,000 ft from the San Andreas Fault, will begin in March and continue for four years.