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Engineering feat protects Bay Area water supply

Hetch Hetchy. (Hetch Hetchy.)
Residential water bills in San Francisco may soon go up by as much as $7-$10 a month after the San Francisco Public Utilities Commission voted on Tuesday to increase water and sewer rates to help pay for improvements to the system. The rate hike proposal will now go to the Board of Supervisors for final approval next month and it is expected to pass.

ABC7 News got an exclusive look at one the innovative projects the city is working on to protect its water supply. We were taken underground to see how officials will keep water literally moving when a big earthquake hits.



From the ground, it looks like any other hole in the ground at a construction site. But go below ground and it's obvious why this one is special.

Alan Johanson oversees this project for the San Francisco Public Utilities Commission.

"The Hayward Fault runs right below and right through this area," he said.

Keeping this pipe working during a major earthquake, means to secure the water supply for millions of people in the Bay Area.

Johanson showed us the massive room being built to house a huge pipe. Slits in the walls allow it to move if there is an earthquake.

Down the middle, a 72-inch pipe will keep water flowing. Engineers designed two of the largest ball joints ever manufactured to make sure it stays intact.

Animation provided by the San Francisco PUC shows how the two work together. When a quake hits the pipe will sway and the walls will move.

"It's designed for up to six and a half foot of earth movement," said Johanson.

The new pipes will replace ones built in 1952 and 1973. They deliver water to 2.6 million customers in Alameda County, the South Bay and up the Peninsula to San Francisco.

The $32 million project is paid for by taxpayers. Voters approved a $4.6 billion ballot measure in 2002 to repair and replace the aging Hetch Hetchy water system.

An engineering marvel at the time, the system of pipes, dams and reservoirs carries water 167 miles from Yosemite National Park, across the Central Valley and into the South Bay before going up the Peninsula to San Francisco.

"The promise of the Hetchy program is to deliver water within 24 hours of an earthquake," said Johanson.

Most of the work on the Hetch Hetchy seismic upgrade has already been completed. And 80 percent of the projects are now finished.

Work on this project is expected to be completed early next year.

Written and Produced by Ken Miguel.
Related Topics:
science yosemite yosemite national park california california water water alameda county san mateo county san francisco county Assignment 7 Fremont San Francisco Daly City
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