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Pipe break cuts Hetch Hetchy supply in half
Rupture near Modesto creates ripple effect across Bay Area

Phillip Matier, Andrew Ross Wednesday, November 13, 2002
San Francisco Chronicle

A spectacular rupture in a Hetch Hetchy pipeline near Modesto has touched off a chain reaction resulting in the loss of more than half the water that comes from the Sierra to 2.4 million customers in the Bay Area.

"We are not at a point where we have to tell the public they have to curtail their usage," Pat Martel, head of San Francisco's Public Utilities Commission, said Tuesday -- but she also warned that officials might have to put out a call for conservation if the problem isn't fixed soon.

The 1960s-vintage pipe that burst in a cow pasture west of Modesto early Sunday is one of three major lines that bring water 167 miles from Yosemite National Park to the Bay Area. The reason for the rupture is still unclear, but the effect was plain to see -- a geyser shooting 100 feet in the air for nine hours. By the time the pipe was patched, more than 70 million gallons had been lost.

The rupture set off a chain of events that show just how fragile the Hetch Hetchy water system is.

To repair the pipe, a 30-mile stretch of line had to be shut down. That meant closing a major gate in the system.

But when engineers tried to reopen the 12-foot-by-12-foot gate, it got stuck. The gate also controls the water to the other two major Hetch Hetchy lines.

As a result, water flow from the Sierra was cut about 50 percent, Martel said.

And that was only part of the headache.

As it turns out, two treatment plants in Sunol and on the Peninsula that process water from the PUC's storage reservoirs had cut back their operations for repairs -- so the system's available backup supply was only about half of normal.

Put it all together and you have a plumbing nightmare that has left the system with only about 70 million of the 240 million gallons a day typically used by the PUC's customers.

Late Monday, the PUC issued an emergency alert to its wholesale customers --

which include most cities on the Peninsula -- warning that it wouldn't be able to meet their "peak demands" for water until the problem was fixed. Peak hours are 5 to 9 a.m. and 6 to 8 p.m.

Martel said the 29 suburban water districts in San Mateo, Santa Clara and Alameda counties that depend on Hetch Hetchy got an updated alert Tuesday advising them to start using their reserves and pumping water from their wells as a supplement.

Martel said systems with substantial backups include Daly City, South San Francisco, Millbrae and the Alameda County Water District. But others are more reliant on Hetch Hetchy.

A spot check of some districts found officials pretty much unfazed, though Palo Alto utilities engineer Scott Bradshaw told us the water coming through the pipes was cloudier than usual.

"It's generally more of an appearance issue," he said, adding that there's nothing wrong with the water from a health standpoint.

San Francisco PUC officials said no customers had contacted them about cloudy water problems and they did not expect to receive any calls.

Some homeowners and businesses have complained in recent days of foul- smelling water -- a problem that popped up when the PUC turned to two of its reservoirs in Alameda County, including one where algae growth had been detected recently.

Martel said the fact that the break happened over a three-day weekend when schools and government offices were closed, along with many businesses, worked in the system's favor by keeping the water demand lower than usual.

But things could get dicey, depending on how long the flow is restricted.

The PUC dispatched a team of scuba divers from San Francisco on Tuesday to assess the problem with the stuck gate -- which sits under about 8 feet of rushing water next to the Don Pedro Reservoir in the Sierra foothills, near the Moccasin Powerhouse.

"We're going to assess whether the dive team can access the gate safely," Martel said.

Martel said she's optimistic the problem can be fixed within the next day or so. But if everything isn't back to normal within the next 48 to 72 hours, retail customers -- the millions of people who take for granted that Hetch Hetchy water will come out of the tap -- could start feeling the pinch.

"It is a vulnerable system, and that's one of the major issues we tried to communicate to the public about the need for our capital program," Martel said.

The break came just five days after San Francisco voters approved selling $1.6 billion in bonds to begin what will eventually be a multibillion rebuild of the aging system.

Art Jensen, general manager of the Bay Area Water Users Association, which represents the Hetch Hetchy system's 29 wholesale customers, said, "This is not a good situation. We know it, and San Francisco knows it. It emphasizes why the work (upgrading the Hetch Hetchy) system needs to be done."

The Modesto geyser is the second major break in the system in as many months.

On the weekend of Oct. 12, one of San Francisco's major mains burst in the Portola district, sending a flood of muddy water though city streets.

Still, the latest break is considered among the system's worst ever -- at least in terms of its domino effect on the water supply.

"Frankly," said Martel, "I feel like the Dutch person sticking my finger in the dike."


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