Calaveras Dam

FlatironDragados, as the lead in a joint venture with Sukut, constructed the Calaveras Dam Replacement Project for the San Francisco Public Utilities Commission. The project replaced the original dam, built in 1925, with a new earth-and-rock-fill dam designed to withstand 7.25 magnitude seismic events on the nearby Calaveras Fault.  

Key elements include:  

• 200-foot-tall dam with 1,220-foot-long crest, 80-foot-wide crest and 1,180-foot-wide base
• 10+ million cubic yards of excavation
• 1,550-ft spillway using 40,000 cubic yards of concrete
• A new intake/outlet shaft tower with a 20-foot diameter, 163-foot-deep vertical shaft and three new adit tunnels

Crews constructed the new dam downstream of the existing dam, using the original dam as a cofferdam, allowing excavation without draining the reservoir and keeping the 85-year-old dam fully operational during construction. When full, the dam provided more than half of the Bay Area storage capacity for 2.6 million customers.

This project was part of a $4.6 billion water system improvement program to repair, replace and seismically upgrade aging pipelines, tunnels and reservoirs in the Hetch Hetchy Regional Water System.  

• 2019 Excellence in Partnering Award, Associated General Contractors of America
• 2019 Northern California Award, Contractor of the Year, American Public Works Association
• 2019 Northern California Award, Structures Projects Over $75 Million Project of the Year, American Public Works Association
• 2019 Safety on a High Hazard Project – First Place, Associated General Contractors of America
• 2019 Heavy Civil Award, Over $100 Million, Associated General Contractors of America
• 2019 Project Achievement Award, Public Works More Than $60 Million, Construction Management Association of America
• 2019 Regional Projects Awards (Sapphire), Engineering News-Record
• 2019 Buildings/Public Infrastructure Projects: $250M Plus, Sapphire Level Award, International Partnering Institute
• 2019 Excellence in a Constructed Project of the Year, United States Society of Dams
• 2019 Best of Infrastructure Award, San Francisco Collaborative Partnering Steering Committee
• 2019 Gold Award Winner Infrastructure Over $30 Million, San Francisco Collaborative Partnering Steering Committee
• 2018 Outstanding Environmental and Engineering Geologic Project Award, Association of Environmental and Engineering Geologists
• 2014 SFPUC Safety Award for over 7 million work hours without a lost time incident
• 2011 SFPUC Safety Award for over 2.5 million work hours without a lost time incident