Hetch Hetchy Water System Improvement Projects

Sina WeiboPrintShare

(KTSF by Jessie Liang)

Since the Hetch Hetchy system has been in service for over 70 years, there has been no major upgrade. Its aging infrastructure may not survive a serious earthquake. In 2002, voters approved a $4.6 billion bond measure that would overhaul the whole water delivery system through 81 improvement projects.

The Calaveras Reservoir in the East Bay was built in 1925. With a capacity of 3.1 billion gallons, it’s the largest reservoir in the area, however it’s determined that the reservoir is not seismically safe. To this day the reservoir stays only 40% full. The U.S. Geological Survey predicted that there’s a 60% chance that a big earthquake will strike in the next 30 years. The Hetch Hetchy system runs across 3 earthquake faults.

KTSF

General Manager of the San Francisco Public Utilities Commission Ed Harrington said, “When an earthquake strikes, we know that people will ask us for water. We also need it to fight fire.”

The General Manger of the Bay Area Water Supply and Conservation Agency Art Jensen said, “If there were a major earthquake, it could put major portions of the Bay Area out of water for up to 60 days. Two months without water, businesses and schools won’t survive. The residents will have a terrible time.“

Director of the Water System Improvement Program Julie Labonte said, “The new Calaveras Dam will be capable of withstanding a 7.25 earthquake on the Calaveras fault, which is just 300 yards away from where we stand.”

Another reconstruction project is the Lower Crystal Springs Dam. SFPUC spokeswoman Alison Kastama said, “What you can see here is work on what’s called the parapet wall. That’s the wall facing the water. They’re doing modification to widen the spillway in case water comes over the top of the dam.”

The agency said the bottom of the dam also requires work to prevent flooding by reducing the water’s flow speed.

There’s the bay tunneling project that runs parallel to the Dumbarton Bridge. It’s the first water supply tunnel that’s 100 feet deep into the bay. Project Construction Manager Bob Mues said, “The air pressure balance is a submarine tunneling system. It’s unique in the 25 to 30 years. The crew works in free air. The front of the tunnel machine is pressurized to resist the water from coming in.”

The New Irvington Tunnel in Alameda County is over 80 years old. Senior Project Manager David Tsztoo said, “The old tunnel would be subject to severe damage if a major earthquake happens on either the Calaveras or the Hayward faults.”

Construction crews use a small scale mining machine that’s suitable for the geology of the area, he said. As a mitigation measure for potential impact on the nearby ecosystem, SFPUC’s environmental inspector Tony Jones said, “Heavy, thick plastic fencing is used to exclude some of the habitat to come into the site, particularly the soft marsh harvest mouse, which is an endangered federal and state species.”

Of the 81 projects, more than half of them are completed. By 2016 when the whole project is finished, water rates will also go up accordingly, Mr. Jensen said. “The customer themselves will reap the benefits, but they’ll be paying the bills and that’s really to be acknowledged. It’s not for the future. All this work is to protect the people and businesses that reside here today.”

If an earthquake interrupts the water supply, SFPUC still has 5 to 6 days of water supply. Manager of Water Supply and Treatment David Briggs said, “We have water trucks and water machine that makes 1 gallon bag of water at a time. We can produce hundreds of them an hour for distribution.

Experts said that families should use containers to store Hetch Hetchy water in a cool place for emergency use, with a date marked on it so that the water will be changed once every 6 months. Each member of the family, including pets, should have at least 3 gallons of water.

(Copyright 2012 KTSF. All Rights Reserved. This material may not be published, broadcast, rewritten, or redistributed.)

Share This

Leave a Reply

Connect with Facebook

*