Pipeline Survives Earthquakes : Emergencies: Officials say it is risky to rely on the mile-long concrete tunnel as the county’s sole supplier of imported water.

A mile-long length of pipeline that supplies most of Ventura County with imported water survived a series of devastating Southern California quakes without major damage, officials said Wednesday.

The pipeline received a clean bill of health, Calleguas Municipal Water District Assistant General Manager Ron Marchelleta said. Recent quakes, however, have renewed officials’ fears about the vulnerability of the county’s water-supply chain.

“Structurally, the tunnel looked just fine. We found a couple minor, new cracks. That’s about it,” Marchelleta said. “But when you only have one source of water, and it’s through a tunnel, that’s the weak link.”

Officials were concerned that they would discover movement in the joints that make up the pipeline, an eight-foot-wide, concrete tunnel running from Chatsworth through the Santa Susana Pass to Simi Valley.

Calleguas conducted the emergency inspection because of the 7.4- and 6.5-magnitude quakes that leveled buildings and homes in the San Bernardino County communities of Landers and Big Bear on Sunday.

The first quake, though centered more than 100 miles away, contained enough power to knock out Calleguas’ hydroelectric generator.

Calleguas is the only supplier of Northern California water to Ventura County. It gets its water from the Metropolitan Water District of Southern California and pumps supplies to 500,000 residents in Camarillo, Moorpark, Oxnard, Simi Valley and Thousand Oaks.

Donald Kendall, a former MWD administrator who was hired in March as Calleguas’ general manager, said officials have believed for some time that relying on one pipeline is risky.

Only a few minutes before Marchelleta and Kendall descended into the tunnel Wednesday for their inspection, a 4.2-magnitude aftershock jolted the San Bernardino area.

The pipeline was completed in 1961 and engineered to weather devastating major earthquakes.

“It is physically situated in the hardest bedrock that exists. That’s why it’s there in that location,” Kendall said. “But that doesn’t mean it won’t collapse. If it goes, it’s going to put you out of service for a long time.”

Two faults lie on or near the pipeline: the Simi-Santa Rosa fault and the Santa Susana thrust fault, he added. Neither fault line represents a greater hazard than the San Andreas, which has shown substantial activity in the past week.

In the event that a quake causes a failure in the pipeline, customers would have to rely on Calleguas’ backup supply at Bard Reservoir.

The reservoir is located between Simi Valley and Thousand Oaks and holds about 10,000 acre-feet of water, or about 3.4 billion gallons. That amount is enough to supply the county’s residents for up to a month, depending on the time of year, before running out.

An acre-foot is about 326,000 gallons, enough to supply two families for a year.

To bolster its water supplies, Calleguas recently moved forward with a plan to create an underground reservoir capable of storing about 300,000 acre-feet of water, Kendall said.

That reservoir, called the North Las Posas Basin, would store more water than the whole county uses in a year.

MWD and Calleguas are also planning for the construction of a new pipeline that will extend from Castaic Lake in Los Angeles County into Happy Camp Canyon Regional Park near Moorpark, Kendall said.

Construction on that pipeline is not expected to start until 1996, Kendall said.

“I’d like to get that pipeline functioning before the year 2000,” Kendall said. “Since this last jolt, maybe we ought to start a little sooner.”