San Francisco completes $288m Bay Tunnel project

San Francisco has completed a $288m seismically resistant underground tunnel under San Francisco Bay to provide reliable water supply to the US city.

Bay Tunnel has started delivering drinking water from Hetch Hetchy reservoir to Crystal Springs Reservoir.

The pipe is five miles long with a nine-foot diameter and runs around 75ft to 100ft below the sand and silt of the Bay from Newark to Palo Alto.

The San Francisco Public Utilities Commission’s (SFPUC) tunnel replaces two aging pipelines that had leaked millions of gallons of water into the Bay, and has been opened for service after weeks of testing and disinfection.

San Francisco Mayor Ed Lee said: "Protecting our water supply also protects our entire regional economy.

"The new Bay Tunnel is part of San Francisco’s multi-decade effort to upgrade the seismic reliability of our Hetch Hetchy Regional Water System and strengthen our water and sewer infrastructure to prepare for the next big earthquake."

The project involved a cost of $288m, which is much less than the original estimation of $313m.

Construction for the tunnel had started in April 2010.

The project is one of the last under SFPUC’s Water System Improvement Programme (WSIP), which aims to improve water infrastructure in the country.

SFPUC general manager Harlan L. Kelly, Jr. said: "The new Bay Tunnel will ensure that we have reliable access to Hetch Hetchy water at all times, particularly within 24 hours of a major earthquake."

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Image: San Francisco, Oakland, and the Bay Bridge. Photo: courtesy of SamuelWantman / Wikipedia.