Concrete Spillway Completed on Calaveras Dam Replacement Project
The construction of a new 1,550-foot-long spillway utilizing 40,000-cubic-yards of concrete has now been completed at the Calaveras Dam Replacement in Sunol, Calif. The project will replace the original dam, built in 1925, with a new 210-foot-high earth and rock fill dam designed to accommodate earthquakes on the Calaveras Fault.
The San Francisco Public Utilities Commission has awarded a $500 million construction contract to the joint venture of Dragados USA, Flatiron and Sukut Construction.
Construction of a new intake/outlet tower consisting of a 20-foot-diameter by 163-foot-deep vertical shaft and three new tunnels to convey water to and from the reservoir is complete and the outlet works are under construction now with plans to complete the work this summer.
The new dam is being constructed next to the existing dam, which will be left in place. Roughly one third of the existing dam will be removed so that water flows between the new and existing dams. The existing dam will create a peninsula into the reservoir. Approximately seven million cubic yards of material is being excavated to construct the new dam.
The Calaveras Dam is part of the Hetch Hetchy Regional Water System that provides drinking water to 2.6 million people in Alameda, Santa Clara, San Mateo and San Francisco counties. Since 2001, after Calaveras Dam was deemed seismically unsafe by the California Division of Safety of Dams, water levels in the reservoir have remained at 40 percent of full capacity. The project will allow the water levels back to the historic capacity of 31 billion gallons.
The replacement project is part of the SFPUC’s $4.8 billion Water System Improvement Program to repair, replace, and seismically upgrade the aging pipelines, tunnels and reservoirs in the Hetch Hetchy Regional Water System.
Flatiron has a 30 percent share in this joint venture. Joint venture partner Dragados USA has a 40 percent share, and Sukut Construction has a 30 percent share.