Work Begins To Replace Calaveras Dam
ALAMEDA COUNTY (CBS SF) -- The San Francisco Public Utilities Commission broke ground Friday on a new Calaveras Dam in unincorporated Alameda County, part of a major seismic upgrade to the Hetch Hetchy water system.
The Calaveras Dam, located northeast of Milpitas, was deemed seismically unsafe by the California Division of Safety of Dams in 2001, forcing the SFPUC to keep water levels in the Calaveras reservoir at 40 percent of capacity.
The $416 million replacement project will build a new 220-foot earth and rock-filled dam next to the existing dam, which will be left in place and fully submerged when the new dam is complete.
The new dam will include approximately 7 million cubic yards of material, a new 1,550 feet-long spillway, fish passage screens and a fish ladder and a new intake/outlet tower. When complete, the new dam will allow the reservoir to return to its historic capacity levels of 31 billion gallons.
"The amount of material that will be excavated to build the new dam is the equivalent of two Great Pyramids of Giza," said SFPUC General Manager Ed Harrington. "That is the size and scale of the projects we are constructing to improve the seismic and water reliability of the Hetch Hetchy water system."
The replacement project is part of a $4.6 billion Water System Improvement Program aimed at repairing, upgrading and seismically retrofitting the Hetch Hetchy water system. The system, owned by the City of San Francisco, provides water to more than 2.5 million people in the Bay Area.
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