With a budget of $718 million, the Calaveras Dam Replacement dwarfs other projects in SFPUC's Water System Improvement Program. Located in the Sunol Valley southeast of Fremont, the project replaces the original dam, built in 1925.
The reservoir provides most of the water storage capacity for SFPUC. However, in 2001, the seismically unsafe dam's proximity to the Calaveras Fault—just 1,500 ft away—led officials to lower its capacity by more than 60%. A joint venture of Dragados USA, Flatiron West and Sukut Construction began work on the new, 220-ft-high zoned earth-and-rock-fill dam in 2011. Completion was originally scheduled for 2015. However, in 2012, during excavation of the left abutment, the project team uncovered two ancient landslides that had not been found during earlier geotechnical investigations. Despite this discovery, a third-party review found the design team had performed proper due diligence, Wade says.