State Weighs Mobil Refinery Cleanup to Halt Ground-Water Contamination

State water officials say a huge plume of gasoline from the Mobil Oil Corp. refinery in Torrance has contaminated ground water at least 1,200 feet from the refinery grounds, and they have tentatively ordered the company to begin a massive cleanup.

Concerned about a potential threat to drinking water, the Los Angeles Regional Water Quality Control Board distributed the preliminary order late last week directing Mobil to stop the spread of “ground-water pollution caused by the uncontrolled release of hydrocarbons” from the refinery.

The order, which the state agency will consider making final at a meeting on March 28, instructs Mobil to draft a cleanup plan within a month or face fines of up to $1,000 a day.

A Mobil spokesman said the company had not received a copy of the board’s tentative order and would not comment on it.

Tests of wells drilled at the refinery and in Torrance’s nearby industrial redevelopment area have found levels of benzene, a cancer-causing chemical, thousands of times higher than the state standard for drinking water.

High levels of other toxic chemicals, including toluene, xylene and ethylbenzene, have been found at wells south and southeast of the Mobil refinery’s gasoline storage tanks at Van Ness Avenue and Del Amo Boulevard. There is no danger of an explosion, state officials said.

American Honda Motor Co. is planning to build its North American headquarters on the 25-acre redevelopment site where ground-water contamination has been detected. The contamination will not prevent construction but could force delays depending on the nature of the cleanup.

Tests Ordered 3 Years Ago

The tentative cleanup order comes more than three years after the regional board directed Mobil and 14 other refineries in Los Angeles County to conduct tests to determine the extent of ground-water pollution under their facilities.

Jim Ross, engineer in charge of the board’s refinery inspection project, said test results show the ground-water pollution at Mobil is “the largest off-site migration” of any of the refineries that have been studied.

He said the most recent tests show the contamination has spread from the shallow ground water into the deeper Gardena aquifer. An aquifer is an underground layer of porous rock or sand that contains water.

“It’s just becoming evident what is down there,” Ross said. “There is obviously some potential threat to drinking water because it’s down to a regional aquifer.”

However, so far, Ross said, he knows of no drinking water supplies that have been affected by the contamination.

And Charles Schaich, senior administrative assistant for the Torrance water system, said their tests show “no evidence at all that we’ve had any contamination in our wells.”

“But to be on the safe side,” Schaich said, “we will increase our sampling.”

About 15% of Torrance’s drinking water comes from wells, but the water is pumped from the Lynwood and Silverado aquifers, which lie far below the contaminated Gardena aquifer. (The aquifer is named for Gardena, but it does not supply that city’s water. Gardena purchases water from the California Water Co.)

Schaich said the contamination is apparently moving in the opposite direction from the city’s three wells, which lie to the north and west of the refinery.

Although he would not comment on the tentative cleanup order, Thomas Gregory, manager of safety and training at the Torrance refinery, refused to accept the board’s conclusion that Mobil is responsible for the off-site ground-water pollution.

“The source of that contamination is certainly unknown,” he said.

Gregory acknowledged that Mobil repaired leaks in three gasoline storage tanks recently and is aware “there is some contamination under the refinery.”

Extensive Monitoring

At the board’s insistence, Mobil has had an extensive ground-water monitoring program in the area for two years and is planning to recover the gasoline that has been found in pools beneath the refinery. The volume of gasoline beneath the surface is not known.

Ross said tests conducted in the area have found three pools of “free hydrocarbon”--basically refined gasoline--on the surface of the shallow layer of ground water about 30 feet beneath the western portion of the refinery.

The gasoline floating on top of the ground water lies in pools that in some cases are 25 feet thick, Ross said.

The most recent testing also found two plumes of dissolved hydrocarbons in ground water located in the deeper Gardena aquifer about 75 feet below the surface, Ross said.

The major plume originates beneath Mobil’s southeastern gasoline storage tanks and is estimated to be about 5 feet deep and at least 400 feet wide when it leaves the site.

The contamination extends at least 1,200 feet from the refinery. “We haven’t gotten to the tip of it, so more assessment will be required to determine the extent of the plume,” he said.

Readings at a well 1,200 feet southeast of the intersection of Van Ness Avenue and Del Amo Boulevard showed benzene levels of 8,000 parts per billion. The drinking-water standard is 1 part per billion, Ross said.

Levels were even higher in the Torrance redevelopment area, as much as 47,000 parts per billion, according to Ross.

“We’re extremely concerned by this,” he said.

So is the City of Torrance, which has been working with Honda to develop the area as offices.

In recent months, the Torrance City Council has been meeting in executive session to discuss possible legal action against Mobil. So far, no action has been taken.

Data from two monitoring wells east southeast of Mobil Oil storage tanks shows that gasoline contamination of ground water has moved at least 400 feet east and 1,200 feet southeast of the refinery site. However, readings at wells on Del Amo Boulevard due south of the tanks show very low levels of contamination.