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Replacing vital Bay Area water link a delicate endeavor

Posted by: Maven on December 29, 2009 at 7:25 am

From the San Francisco Chronicle:

“The last time engineers got a peek inside Irvington Tunnel, the 3.5-mile-long linchpin of the Bay Area’s water system, Willie Mays had just inked the most lucrative contract in baseball history, the Beach Boys’ “Good Vibrations” was a hit, and the future Silicon Valley was blanketed with zucchini and apricots.

The year was 1966.

Since then, the tunnel in the hills above Fremont has become so indispensable that its operators at the San Francisco Public Utilities Commission can’t take it out of commission to check for leaks or blockages or to make repairs – despite the fact that the worn concrete and timber tube dates back to the late 1920s and lies between two major earthquake faults.

Last month, however, the water agency that supplies water to 2.5 million people in San Francisco and parts of San Mateo, Santa Clara and Alameda counties cleared a major hurdle in the effort to relieve the strain on Irvington. The board approved a $250 million project to build a sister tunnel parallel to the existing tunnel. Construction is expected to start in the spring and be completed by early 2014. … “

Read more from the San Francisco Chronicle by clicking here.

The San Francisco Examiner continues it’s in-depth & excellent coverage of the Hetch Hetchy Water System Improvement Program with this story on the tunnel project:

” … The pipes that cross the water leak badly, leading vegetation to flourish at their corroded metal seams. But the ramshackle 1920s-era bridge crosses sensitive wetlands that are protected by federal environmental laws. Those laws effectively prevent water officials from accessing or maintaining the pipeline.

“You basically can’t walk on it,” Project Manager Joe Ortiz said. “We have some pretty extensive environmental regulations — certainly the most that I’ve seen on any project that I’ve worked on in 23 years. In the ’20s, they could do anything. But nowadays, with our regulations, it’s almost impossible to step on the land.”

An underwater 9-foot-wide metal pipeline is planned to eventually replace both Bay-crossing pipes, although it’s not known whether they will be removed because dismantling efforts could disrupt wetland wildlife.

Tunnel construction efforts using a heavy-duty tunnel-boring machine are expected to begin next year and last until 2015. The tunnel will pass up to 100 feet beneath the Bay floor. … “

Read more from the San Francisco Examiner by clicking here.

December 29, 2009 · Filed Under Bay Area

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