Water Main Fixed, South County Will Get Back in Flow

Water is expected to begin flowing as usual to South County this afternoon, after repairs to a ruptured section of the 26-mile Allen-McColloch pipeline were completed over the weekend, authorities said Sunday.

Crews wrapped up the repairs about 4:30 p.m. Saturday and began filling and pressurizing the water main at 7 a.m. Sunday, following an inspection, said Bob Muir, spokesman for the Metropolitan Water District of Southern California. The line was running at full capacity by 2 p.m., but won’t be made available to the public until routine water quality testing is completed.

“The next step in bringing the line back into service is the taking of water quality samples to identify the bacteria count,” Muir said. “That takes about a 24-hour turnaround. We’re also monitoring the chlorine residual as a safety measure. We hope to have all these results back by midday Monday.”

The 69-inch-diameter pipeline--buried 25 feet below a strawberry field in Irvine--exploded a week ago, blowing out a 10-foot section of the steel-and-concrete conduit. The force of the blast blew chunks of concrete into the air and spilled about 5 million gallons of water.

On Friday, investigators attributed the water main failure to computer software problems, inadequate training or human error. An investigation will also determine whether operators responded appropriately, and if not, whether they had been properly trained, officials said.

The rupture forced 700,000 South County customers to resort to drought-like water restrictions. The conservation measures were so successful, authorities said, that local reservoirs were actually rising because of the drastic cutbacks in water usage.

Keith C. Coolidge, associate general manager of the Municipal Water District of Orange County, said South County residents used 23% less water during a 24-hour period ending at 8 a.m. Sunday.

During that same period the Santa Margarita Water District reported a 43% drop in water usage from an average of 27.8 million gallons per day before the rupture to 15.9 million gallons, Coolidge said. The district services Mission Viejo, Rancho Santa Margarita, Coto de Caza, Ladera Ranch and Talega Valley.

The Los Alisos Water District, which serves mostly Lake Forest, also reported a 34% decline in water usage for a 24-hour period ending at 8 a.m. Sunday, Coolidge said. The district’s customers normally use 6.7 million gallons per day but only used 4.4 million gallons.

“A big thanks to everybody in south Orange County for conserving water during this emergency. The public’s cooperation was a big factor in helping us meet this emergency,” Coolidge said.

Water officials said crews worked around the clock for a week to repair the pipeline. Muir said workers finished welding the three 20-foot sections used to repair the conduit at 4 a.m. Saturday. The concrete coating of the inside of the sections was completed the same day at 4:30 p.m.

Technicians also inspected the inside of the pipeline, 2,700 feet downstream of the break and 1,900 feet upstream, looking for cracks. Sergio Valles, who is in charge of the construction repairs, said a relatively new technology that employs electrical current was also used to check for breaks.

“The wires wrapped around the pipe create a magnetic coil. As you walk through the pipeline with this eddy current device, it measures any voltage drop,” Valles said. “A voltage drop indicates a break in the wires inside the pipe, which equates to a weakness in the structure.”

Muir said that workers also patrolled all 26 miles of pipeline on the surface, inspecting air release valves and structures. Repairs are expected to cost about $750,000 but will not result in a rate increase, authorities said.