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Good Tunnel vs. Bad Tunnel

When enviros want to build a tunnel to bring pure Hetch Hetchy/Yosemite water under the Bay-Delta to San Francisco, no problem.

Oct 21, 2013

When ag interests in the Central San Joaquin Valley explore the possibility of building tunnels under the Delta to bring water to Valley farms and the people of Southern California, all we hear about are the environmental concerns of such a project. But, when enviros want to build a tunnel to bring pure Hetch Hetchy/Yosemite water under the Bay-Delta to San Francisco, no problem.

Dan Bacher's analysis in the Daily Kos of the proposed Delta tunnels said, "the problem is that the very concept of a peripheral tunnel or canal, regardless of whether it is a single or twin facility, is an outdated Nineteenth Century solution to a Twenty-First Century problem."

In the article below they make the outdated Nineteenth Century solution sound more modern: "Engineers here like to say the machine “eats dirt and spits out a concrete tunnel. Driving the machine were miners who spent ten-hour work days 100 feet below daylight. When they got to the other side of the tunnel, they were less than a quarter of an inch off target."

Wow? A quarter of an inch? With all that outdated technology? When they build a tunnel using antiquated Nineteenth Century technology to deliver water to San Francisco, they can make it sound pretty good. Not one mention of any environmental problem. When the water's for them, they're going to get it. There are rules for them, and there are rules for us.


Inside the New Tunnel 100 Feet Below San Francisco Bay


By Molly Samuel and Amy Standen

Thursday is the 24th anniversary of the Loma Prieta Earthquake, which, aside from damaging the Bay Bridge and disrupting a World Series game, reminded Bay Area residents that our water system is on shaky ground. (Well, it probably didn’t really remind everyone of that.)

The tunnel is five miles long and 15 feet in diameter, built with concrete and steel pipeline. It’s not quite finished, but to commemorate the earthquake anniversary, the SFPUC invited media down into the tunnel, to see the thing before it fills up with water from the Hetch Hetchy.

So in 2002, San Francisco got around to passing a ballot measure to seismically retrofit the water system. And in 2010, the San Francisco Public Utilities Commission started construction on a tunnel under the Bay that’s intended to be able to deliver our drinking water, rain or shine or earthquake. The $286 million tunnel is the first that’s actually beneath the Bay; BART’s Transbay Tube sits on the bottom of the Bay.

One end of the tunnel is in Menlo Park, the other end is in Newark. An elevator on the Menlo Park side goes down more than 100 feet to the opening of the tunnel.

To dig the tunnel, the SFPUC brought in a $10 million custom-made tunnel-boring machine from Japan. Engineers here like to say the machine “eats dirt and spits out concrete tunnel.” Driving the machine were miners who spent ten-hour work days 100 feet below daylight. When they got to the other side of the tunnel, they were less than a quarter of an inch off target — “well within the margin of error,” says Program Director Julie Labonte.

The SFPUC expects to finish working on the tunnel in late-2014, six months ahead of schedule.

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