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Report Says Rotting Plants, not Oil Well, Caused Gas Blast

June 13, 1985

LOS ANGELES (AP) _ Methane that exploded last March in a store basement, injuring 21 people, was probably produced by decomposing organic matter, a city task force says.

The report Wednesday to the City Council said that an abandoned oil field beneath the neighborhood of the Ross Dress for Less store was probably not the cause of the blast, which forced evacuation of a large area in the Fairfax district.

Instead, chemical analysis indicates a gas pocket was formed ″from the decomposition of buried plant materials at no deeper than 100 to 200 feet below ground level,″ said the report by the 16-member task force.

Meanwhile, officials of an exclusive housing project in suburban Manhattan Beach said they have measured methane levels as high as 100,000 parts per million, nearly twice the explosive level, at the site.

However, they and state health officials said the gas, produced by the decomposition of oily residues from an old Chevron USA Co. tank farm, poses no immediate health or safety threat.

The Los Angeles panel, made up of representatives of such agencies as the Fire Department, county Department of Public Works and the state Division of Oil and Gas, also recommended measures to be taken in a 400-block area to help prevent a recurrence of the explosion.

It suggested that homeowners with basements be required to install alarm systems and that owners of larger buildings take other steps that could cost thousands of dollars.

Councilman Zev Yaroslavsky, who represents about half of the potential risk zone, said the recommendations will require considerable discussion.

″It’s not a foregone conclusion that we will just blanket that area with detection devices at the public’s own expense,″ he said. ″But safety is also a concern. It may be that in the core area we may have to bite the bullet (and require gas detectors).″

He said the city would not be able to foot the bill, though funds from the federal government or low-interest bank loans might be available.

Frank V. Kroeger, general manager of the city’s Department of Building and Safety, said homeowners are less at risk than other property owners because most houses have unpaved yards that generally allow natural ventilation of any gas to reach the surface.

Meanwhile, state officials said they are analyzing the possibility that low levels of benzene and other cancer-causing chemicals found at the Manhattan Beach site could pose long-term health problems.

Chevron Land Corp., which owns the property, halted home sales in March after discovering the underground methane gas at a golf course. Tests were conducted after the Chevron refinery in nearby El Segundo discovered that gas was leaking into adjacent underground areas.

Chevron Land plans to install a vapor-recovery system within the next six months to ″suck up″ the fumes at the Manhattan Village project, spokesman Gary Luque said Wednesday.

Luque said a three-month investigation found that the methane, 30 to 50 feet underground, is under no pressure and that there is ″virtually no risk of a Fairfax-type situation.″

No fumes have been detected in any of the 160 condominiums and homes already occupied or the 50 under construction, he said. State Department of Health Services spokesman Rick Notini agreed that the situation ″is completely different from Fairfax, because the levels in Manhattan Beach are low by comparison and are not under any pressure.″

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