Racing to beat the summer dry season and a pending crackdown on water contamination, work crews are plugging a series of leaks that have sent crude oil gushing into a Sylmar tunnel that supplies drinking water to the Los Angeles area.
The work has required the Metropolitan Water District of Southern California to shut down the 5 1/2-mile-long Newhall Tunnel, cutting off the northern portion of the Los Angeles Basin from its regular Northern California water supply since Dec. 1.
Workers are installing a custom-made steel liner inside a half-mile portion of the 20-foot-wide tube, which burrows beneath the San Gabriel Mountains to connect Los Angeles with the state’s California Aqueduct.
As a result, many residents of the west San Fernando Valley, eastern Ventura County and beach cities along Santa Monica Bay have been receiving Los Angeles city water from the Owens Valley on the east side of the Sierra. That water has a different taste and has generated some complaints to water agencies.
The repairs will have cost $11.5 million when completed later this month, according to the Metropolitan Water District.
Water district engineers say an oil field about 200 feet underground is to blame for contamination of the 17-year-old tunnel.
Officials say they have known since 1971, when the tunnel was drilled through an area a few hundred yards east of Golden State Freeway at the Newhall Pass, that the location had “an oil-bearing geological formation.”
Shortly after the oil was discovered, workers drilling half a mile away struck a pocket of methane, a natural gas found in oil fields. The methane caused a small explosion on June 23, 1971, that injured four workers.
The next day, however, a much larger explosion killed 17 members of the tunnel drilling crew. The explosions triggered a series of civil lawsuits and led to criminal convictions for the tunnel builder, Lockheed Shipbuilding & Construction Co., and several of its employees.
When the Newhall Tunnel was completed and put into service in 1972, officials figured that its 21-inch-thick concrete walls would keep the oil out.
But as it aged, the concrete began to shrink and oil began seeping through minuscule cracks.
At first, water district technicians tried to skim the oil from the top of the water at a tunnel opening at the northern edge of the San Fernando Valley.
Then the trickle turned into a steady flow. “It wasn’t just oozing. You could see it running out,” said Ted Huff, a Metropolitan Water District inspector.
“We tried everything--grouting up the cracks, piping the oil out,” Huff said. “Nothing worked. You’d plug one hole and it would find its way out another place.”
The oily buildup began causing occasional taste and odor problems a mile away at the district’s Jensen Filtration Plant in Granada Hills. Later, oily water started clogging filters. Engineers were forced to dump “large quantities of contaminated water” into the Valley’s Bull Creek, according to district documents.
When the federal Safe Drinking Water Act was amended in 1986 to require that petroleum-related organic compounds be removed from domestic water supplies by this June, officials began looking for solutions, said Dan Askenaizer, a water quality specialist for the district.
The tunnel lining project was approved after experts concluded that it would cost $255 million to design and build a filtration system that could skim off floating oil and absorb suspended petroleum compounds. Such equipment could cost up to $21 million a year to operate, according to a water district consultant.
The new tunnel lining consists of 146 tubular sections of half-inch-thick steel. The 20-foot-long sections, weighing 13 1/2 tons each, are bolted and welded together.
Mindful of the danger posed by methane, officials are using three large fans at an opening 3 1/2 miles north of the wall-lining site to draw fresh air into the tunnel.
A 110-member crew has worked around the clock, seven days a week, to hurry the project along, said Huff, who is overseeing the project.
Tim Skrove, a Metropolitan Water District spokesman, said the tunnel will be carefully flushed out and cleaned before it is used to pipe drinking water from the Castaic Reservoir to the Jensen Filtration Plant.
He said the tunnel can move about 2 billion gallons a day--enough to supply 3,000 families for a year--when operated at capacity.
Water from the tunnel eventually flows to such communities as Agoura Hills, Westlake Village, Calabasas, Thousand Oaks and Simi Valley, Skrove said. It also supplies Santa Monica and other cities along Santa Monica Bay.
5% of L.A. Water
He said the Metropolitan Water District also supplies about 5% of the water used in the city of Los Angeles, which has its own aqueduct to the Owens Valley.
During the tunnel shutdown, water district engineers are supplying their clients with city water--a move that has produced grumbles from some homeowners in the Las Virgenes Municipal Water District west of the Valley.
There have been “taste and odor problems” with the city water, said Roger Huff, the Las Virgenes district’s water superintendent.
He blamed the complaints on how the water is treated before it is piped to homes--on “the difference between chloraminated water and chlorinated water.” The city’s water is treated with chlorine and water district’s with chloramine, an alternate disinfectant.