- Location California
Michels constructed the first-ever tunnel to be built under San Francisco Bay. The tunnel was built as a joint venture with Jay Dee Contractors, Inc., and Frank Coluccio Construction Co. Construction of the 5-mile long, 15-foot diameter tunnel began at the 141-foot deep, 58-foot diameter Ravenswood Shaft in Menlo Park, Calif. The shaft has 3-foot thick watertight walls and a 12-foot thick concrete floor slab for strength and support. After the shaft was built, a custom-built tunnel boring machine (TBM) was lowered to the bottom and began its journey under the bay. The tunnel was dug more than 40 feet below the floor of the bay, which will help to protect it against a major earthquake. The Bay Tunnel is part of SFPUC's Water System Improvement Program. The program was designed to upgrade the aging Hetch Hetchy Water System, which provides water from the Hetch Hetchy Reservoir in Yosemite National Park to the 2.5 million people in the Bay Area.
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