Bay Tunnel Design
Location: San Francisco, California
Owner: San Francisco Public Utilities Commission (SFPUC)
Market: Water
Construction Cost: $280 Million (Estimated)
Construction Start/End: 2009/2013 (Estimated)
Jacobs Associates’ Role: Prime Design Consultant
This project constitutes part of the SFPUC’s master plan to upgrade the Hetch Hetchy Water System, which brings water from Yosemite to the San Francisco Bay Area. The Bay Tunnel will extend 5 miles in length underwater, replacing an old pipeline built in the early 1920s and 1930s.
With this project Jacobs Associates faces the challenge of designing the first tunnel excavated by a tunnel boring machine (TBM) under the San Francisco Bay. The tunnel will lie at depths ranging from 75 to 110 feet in sandy and silty clays under high groundwater pressure. Due to these ground conditions, Jacobs Associates will specify that the excavation use pressurized face technology with an earth pressure balance TBM. The tunnel’s internal finished diameter will measure approximately 108 inches.
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