A Flood of Inspections?

The violent rupture of a south Orange County water main Monday may lead to more rigorous inspections of 170 miles of similar, corrosion-prone pipelines around Southern California, water district authorities said Thursday.

The Metropolitan Water District, which provides drinking water to 16 million residents from Ventura County to the Mexican border, may also launch a comprehensive evaluation of its entire 475-mile network of pipelines.

“What we’re going to be doing is looking at our entire infrastructure,” said Jill Wicke, the agency’s director of water systems operations. “Metro has been providing water since 1941, so some of our infrastructure is quite old.”

Among the agency’s greatest concerns is the 170 miles of “prestressed” concrete pipe, the kind used in the South County main that ruptured and forced 700,000 residents to adopt drought-like water restrictions.

Repair crews on Thursday began replacing three, 20-foot sections of damaged water main with new, welded-steel segments. Wicke said the pipeline is expected to be repaired, disinfected and providing water by Monday evening.

South County cities are expected to have more than adequate supplies of water until the repairs are completed, thanks in large measure to the swift response by residents to a plea for conservation.

“There has been an overwhelming response,” said Karl Seckel, principal engineer of the Municipal Water District of Orange County.

Water use has dropped by more than half in some areas, officials said. Most dependent on the water main are the Santa Margarita and Los Alisos water districts, which include Lake Forest, Mission Viejo, Rancho Santa Margarita, Coto de Caza, Ladera Ranch and Talega Valley.

Neighboring cities connected to the South County’s second main water pipeline have been able to transfer water to the needy communities. In fact, water reserves in the Los Alisos and Santa Margarita districts increased Thursday by 4.4 million gallons from the day before, officials said.

Seckel stressed, however, that the conservation effort must continue to avoid a water emergency.

Horticulturist Tom Ash of the University of California extension office in Irvine said trees, shrubs and most ground-covering plants will survive the water cutoff with little difficultly.

Some lawns may show signs of stress, however. With the warm weather forecast for the weekend, some lawns may begin to turn gray. Blades of grass may also begin to curl.

“That’s OK,” Ash said. “It’s not going to die. It’ll start to green back as soon as you put water on it next week.”

The cause of the pipeline rupture is expected to be announced today.

A substantial surge in water pressure detected shortly before the rupture is the likely culprit, but inspectors are also trying to determine whether the pipeline also was weakened by corrosion, Wicke said. It’s possible both were factors, Wicke said.

The water main, buried 25 feet below a strawberry field in Irvine near Portola Parkway and the Foothill Transportation Corridor, exploded on Monday morning with enough force to blow chucks of concrete to the surface. More than 5 million gallons gushed out of a gaping 10-foot hole in the line.

The Metropolitan Water District stopped installing prestressed concrete water mains about five years ago after the pipe was blamed for devastating ruptures throughout the nation, including San Diego and Simi Valley.

The agency also was forced to retrofit 1,000 feet of that kind of pipe near the Los Angeles-Orange County border after finding cracks and signs of corrosion, a repair that cost an estimated $1 million.

Water districts in San Diego and Ventura County are retrofitting similar water mains with steel-pipe inserts.

The Metropolitan Water District has no plans to do so but may start conducting more inspections of those pipelines. The agency currently drains and inspects the insides of those water mains every five years.