Rushing to repair a water main before more than 700,000 people run out of water, Orange County officials said Wednesday that they were gratified by the swift response to a plea for conservation.
Water officials continue to seek the cause of the Monday rupture and said they may consider a costly retrofitting operation to reinforce 170 miles of prestressed concrete pipe around Southern California prone to similar breaks.
Water use has dropped as much as 44% in some areas since Monday, officials said. While much of the decrease was attributed to mandatory restrictions on large-scale irrigation, residents also have conserved voluntarily, officials said.
"We're relying on the residential consumers to get us through this," said Karl Seckel, principal engineer of the Metropolitan Water District. "We need to continue to employ conservation throughout the duration of the outage."
Seckel said repair crews are working around the clock to replace three 20-foot lengths of concrete and metal pipe buried 25 feet below an Irvine strawberry field. The pipe ruptured like a bomb going off Monday morning, shooting shards of pipe and concrete to the surface and into the air. More than 5 million gallons of water were spilled before the flow was stopped, restricting supplies for about 700,000 customers in south Orange County.
Officials have not pinned down a cause of the break, but said Wednesday they suspect that a sharp surge in water flow--from 3.2 million gallons per hour to 4.5 million--was a contributing factor. The surge could have been caused by a valve malfunction somewhere along the 26-mile pipe, which stretches from Yorba Linda to Mission Viejo.
Investigators also suspect that the 20-year-old pipe is prone to corrosion because it is made of a material that has been blamed for several other costly pipeline ruptures across the nation.
If repair work on the ruptured pipe is completed by Sunday as expected, normal water service will be restored the next day, and the crisis will be averted, officials said.
The break affected water supplies in Irvine, Lake Forest, Laguna Woods, Trabuco Canyon, Santiago Canyon, Mission Viejo, Rancho Santa Margarita, San Clemente, Laguna Hills, Dana Point, Laguna Niguel, Laguna Beach, Aliso Viejo and Foothill Ranch.
Times staff writer Phil Willon contributed to this story.