Service station told to clean up leak |

Service station told to clean up leak

Patrick McCartney

State water-quality regulators have given a South “Y” service station a month to begin cleaning up a gasoline leak that may have contaminated a South Lake Tahoe drinking water well.

The USA Petroleum station on U.S. Highway 50 is “the likely source of contamination” of the Tata Lane well, said Ranjit Gill, the chief of the toxics division of the Lahontan Regional Water Quality Control Board.

Lahontan and the South Tahoe Public Utility District have jointly investigated contamination of the well by a fuel additive found in all California gasoline. While the results from a network of shallow monitoring wells is not conclusive, Gill said the presence of the additive, methyl tertiary butyl ether or MTBE, in one of the wells points toward the gas station as the likely source.

“The well is not exactly down-gradient from the gas station, but when you look at the cone of depression caused by three wells in the area, it could possibly pull the gasoline toward it,” Gill said.

In the cleanup and abatement order sent to USA Petroleum of Agoura Hills, Calif., Lahontan requires the company to begin air-stripping and vapor extraction from contaminated soil beneath the station by Nov. 10.

While it was recent testing that led Lahontan to identify USA Petroleum as the likely source of MTBE contamination, the regulator has investigated leaks at the station since 1983 and issued previous cleanup orders to its management.

The station has about a half-dozen monitoring wells of its own to test for contaminated soil, and a thin layer of gasoline was discovered recently in one of the wells, floating on top of groundwater. Lahontan had earlier requested the station’s owners to begin a remediation plan by Oct. 12, but that deadline was extended.

Gill said it was not prudent to wait until final results are in from the investigation of the Tata Lane pollution before ordering USA Petroleum to begin the cleanup.

“We know quite a bit already,” Gill said. “We don’t want to wait until we know the full extent of the leak, because that’s a lengthy process.”

The South “Y” service station not alone in the Tahoe Basin as a source of gasoline leaks. Gill said he is troubled by the discovery of MTBE in groundwater beneath service stations that have already replaced aging fuel tanks with new storage tanks.

“We are seeing MTBE in places where we tested or upgraded the tanks,” Gill said. “It suggests either the leak tests aren’t sensitive enough, the substance is attacking the components or that MTBE is so soluble in water. It’s a mystery.”

The order to USA Petroleum requires the company to come up with a plan by Nov. 24 to measure the extent of the fuel leak, and begin the process of determining the contamination plume no later than Jan. 15.

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