Toxic Plume Taints Town’s Ground Water

Toxic contamination is not what comes to mind at the mention of Cambria, the verdant little tourist town on the Central Coast near San Simeon.

But beneath one of its service stations--and not far from two of its five municipal wells--are concentrations of a gasoline additive more than 30,000 times greater than is permitted in drinking water.

The additive, MTBE or methyl tertiary butyl ether, has become such an environmental scourge that California and federal authorities are banning it.

Cambria officials do not believe the MTBE has reached the two wells nearest the local Chevron station on Main Street, but, with the town depending entirely on wells for its water supply, authorities do not want to take any chances.

The state Regional Water Quality Control Board has directed Chevron Corp. to provide the town with an alternative water source by Sept. 1. The board has also ordered Chevron to stop the contaminants from spreading any farther by June 1.

“I think everybody is in agreement that we wish it had been done yesterday,” said Sheila Soderberg, an associate engineering geologist with the regional board.

The two threatened wells are used for backup in drier weather and have not been pumped for the last two years. Authorities worry that removing water for sampling could draw the pollution into the wells, so they have not been sampled.

The MTBE contamination was first detected in state tests in 1997, but for reasons that are not entirely clear, immediate action was not taken. “It didn’t get the priority it should have,” conceded Jay Cano, senior engineer for the water board.

Ken Topping, general manager of the Cambria Community Services District, said he and San Luis Obispo County Supervisor Shirley Bianchi weren’t even aware that the MTBE had spread until late last year.

“It really did catch everybody by surprise when we discovered there had been a release,” Topping said.

He expressed frustration at the pace of cleanup efforts, and said he was not satisfied that Chevron had fully mapped the extent of the pollution or would meet its deadline.

Chevron was more optimistic. “We’ve made that commitment and are aggressively working to” protect Cambria’s water supplies, Chevron spokesman Ed Spaulding said.

The MTBE plume has crept about 200 feet from the gas station, which remains in operation. That leaves about 500 feet between the leak and the nearest well in the community’s Santa Rosa Creek field, Spaulding said.

All but one of more than two dozen monitoring wells drilled by the company are shallow, leaving unanswered the question of the plume’s depth.

Spaulding said additional deep wells will be dug in the near future. In the meantime, the company has been removing some contaminated water from the center of the site and does not believe the MTBE is migrating directly toward the wells.

He said Chevron has not settled on a final cleanup plan but will probably ensure that Cambria can use the two threatened wells by installing a treatment system at the wellheads.

New underground tanks were installed at the station in 1995 and Chevron believes the leakage occurred before that. Pressure tests conducted on the new tanks last winter indicate they are not leaking, Spaulding said.

Noting that such tests are not foolproof, Cano of the regional water board called the contamination a serious problem. At the same time, he said, Chevron has been working adequately on the cleanup in recent months.

“It’s moving along very rapidly,” compared to some other contaminated sites, Cano said.

Testing at the site has revealed other gasoline contaminants in the ground water along with the MTBE, which has been detected at levels as high as 165,000 parts per billion. The standard for drinking water is 5 ppb.

Added to gasoline to reduce pollution in car exhaust, MTBE has emerged as a serious environmental problem in recent years, forcing the shutdown of wells that supply drinking water to such cities as Santa Monica and South Lake Tahoe.

Cambria, a town of 6,100 visited by thousands of tourists on their way to Hearst Castle in nearby San Simeon, depends entirely on well water.

Its wells are capable of producing a total of 600 gallons a minute--a comparatively small amount as municipalities go, but “for this little community it’s everything,” Topping said.