New Report Shrinks Downtown’s Underground ‘Lake’ of Gasoline

An underground plume of gasoline that has caused consternation for downtown redevelopment officials is significantly smaller than had been thought, a new report says.

As a result, officials of Centre City Development Corp., the agency in charge of downtown redevelopment, now believe the contamination can be cleared in about a year at a cost of $310,000.

It had been feared that a cleanup might cost $5 million and last five years, seriously hindering reconstruction on several blocks between Horton Plaza and the new Convention Center.

The new development was revealed Friday by CCDC’s board of directors. It was the result of a consultant’s analysis of data on the underground reservoir of gasoline gathered by other consultants.

The analysis, done for CCDC by Geomatrix Consultants of Costa Mesa, determined that the underground plume consists of about 10,000 gallons, rather than a lake of 460,000 gallons of gasoline and diesel oil that had earlier been estimated.

The consultant also concluded that the plume is static and not moving toward San Diego Bay, as has been feared.

“The amounts of fuel (are) significantly less, and not hazardous to the bay because it is static,” said David Allsbrook, project manager for CCDC who has overseen much of the agency’s efforts since the underground contamination was discovered.

Paul Gagliardo, a specialist on underground pollution for the city of San Diego who helped evaluated the problem for CCDC, said tests during the past year have revealed that there are 8,000 to 10,000 gallons of free-floating gasoline under parts of six city blocks.

Because the contamination has been there for 30 to 40 years, at least 80,000 gallons have been absorbed into the soil or into the ground water, Gagliardo said.

“There was a fallacy in the original report,” Gagliardo said, because International Technology Corp., one of the previous consultants, measured the thickness of the fuel in a few of the wells, not the formation in the soil.

Geomatrix Consultants has recommended a two-step cleanup. Pumps would be installed to bring the contaminated ground water to the surface. The floating fuel would then be skimmed off the surface and placed in 55-gallon drums for recycling.

The ground water, still contaminated but without free-floating gasoline and diesel, would then be piped back into the ground. The ground water won’t be treated because it’s too expensive, according to officials.

The polluted water would be monitored to determine the extent of contamination to the soil.

Geomatrix Consultants also proposed that each property owner be responsible for removing and disposing of contaminated soil.

“If the free-floating product is skimmed, the problem can’t get any worse, because the source of the problem is gone,” said Gagliardo. “But, as long as it sits there, it contaminates more dirt.”

The cleanup plan also calls for installing wells to test ground water south of Market Street. They would be monitored to see if the ground water is moving toward the bay.

“If the water continues to stay clear, then we’ll know that the problem isn’t moving,” Gagliardo said.

There is still a question of who will pay for the cleanup. CCDC has asked the state Regional Water Quality Control Board to approve the proposed cleanup plan. The regional board, which has thus far identified four property owners as the likely sources of the pollution, has ordered the four owners to submit their cleanup plans by the middle of this month.

The four current and past property owners are Greyhound Bus Lines, which has a maintenance center in the area, the Golden West Hotel, Unocal and Shell Oil Co., which once operated gas stations downtown.

John Anderson, an assistant engineer with the regional board, said a cleanup order against a fifth property owner who operated a defunct Texaco gas station is pending.

In the past, property owners identified as likely contributors to the plume have balked at cooperating, fearing they would be held liable for the entire cleanup.

But CCDC’s Allsbrook said the four property owners who are under orders from the regional board to produce cleanup plans are working on a joint agreement.

The underground plume was discovered in 1986.

In 1988, IT Corp. estimated it could take nearly five years and $5 million to clean up 460,000 gallons of gasoline and diesel fuel floating around between 1st and 3rd Avenues and between Market Street and Island Avenue.

For a while, other CCDC consultants were convinced that the plume--which became known as The Blob--was moving beneath the city streets toward the bay, drawn by underground pumping at the convention center. It’s now clear, according to officials, that such a reading was false.

Discovery of The Blob has delayed some high-rise projects, as private developers waited while CCDC grappled with the problem.