Vapor leakage seen as threat

Fuel-tank safety efforts focus on liquid releases

Gasoline additive found in wells

EPA official says work is `far from finished'

August 23, 2004|By Timothy B. Wheeler | Timothy B. Wheeler,SUN STAFF

Leaks of gasoline vapors from supposedly leak-free underground storage tanks - as Maryland regulators suspect occurred near Fallston recently - threaten to undermine the gains of a 20-year national effort to safeguard drinking-water supplies, according to a federal environmental official.

Cliff Rothenstein, director of the Environmental Protection Agency's Office of Underground Storage Tanks, said last week that although state and federal regulators have made significant progress over the past two decades in cleaning up gasoline and oil leaks, new groundwater contamination seems to be occurring from gasoline-additive vapors seeping out of presumably leakproof systems.

Speaking in Baltimore at a three-day conference on groundwater contamination by oil products, Rothenstein said he was troubled by reports from New Hampshire and other states that vapors from methyl tertiary butyl ether - intended to reduce air pollution - are escaping from underground fuel storage systems that had been upgraded to prevent leaks.

Maryland Department of the Environment officials have also said they believe vapor leaks from an Exxon service station at Routes 152 and 165 could be at least partially to blame for MTBE fouling 169 wells around Upper Crossroads in Harford County - although a two-month investigation has yet to pinpoint any source.

"For years our emphasis has been on preventing and detecting liquid releases" of fuel, Rothenstein said. With recent evidence that MTBE vapors are seeping out of tanks and pipes found to be in compliance with environmental regulations, he added, "We need to get to the bottom of this. We need to find out the source of the problem and ... make sure systems are both liquid- and vapor-tight."

Since Congress passed legislation in 1984 requiring cleanup of a nationwide epidemic of gasoline contamination of groundwater, Rothenstein said, more than 300,000 leaks have been cleaned up. Service station operators have been required to upgrade their fuel storage systems, replacing corroding steel tanks and installing leak-detection monitors. The number of new leaks reported annually has declined from a high of 66,000 in 1990 to about 12,000 last year.

"We continue to make progress, but our work is still far from finished," Rothenstein told the state and federal regulators, and industry officials at the conference. Among the problems remaining, he said, is a backlog of 130,000 leaks nationwide awaiting cleanup, and lack of compliance by some service station operators with regulations designed to prevent leaks or catch them before they can spread to neighboring properties. About 60 percent of storage systems nationwide are in what the EPA deems "significant compliance" with those rules. Rothenstein said he had heard of station operators turning off alarm systems intended to detect fuel leaks or spills.

He said later that federal officials don't know how many MTBE vapor leaks there have been or how much groundwater contamination they may be causing. The agency's data reflect reports only of liquid leaks, he said, because those are all that the leak-detection monitors installed on upgraded storage systems are designed to spot.

"We're trying to get a handle on that," he said, adding that the EPA would need the help of state and industry officials to gauge the extent of the problem and come up with remedies.

MTBE is added to gasoline so that it will burn more cleanly. The EPA has required urban areas with smog problems, like Baltimore, to sell cleaner-burning reformulated gas since the early 1990s. But MTBE dissolves easily in water and has tainted groundwater practically everywhere such gas is sold. Health officials say it is probably not harmful if ingested in the minute doses found in most contaminated wells, but it can render water supplies undrinkable because it has a turpentinelike odor that can be easily detected at very low levels.

Studies in California and New Hampshire over the past several years have reported finding MTBE fouling groundwater beneath service stations that had been upgraded to meet federal anti-leak regulations. New Hampshire officials pointed out they were tending to find contamination around stations equipped to capture gas fumes from the pumps and return them to the underground storage tanks.

Gary Lynn, chief of petroleum remediation for New Hampshire's Department of Environmental Services, said sensitive "tracer" testing of one station confirmed the loss of MTBE from tanks that had been pressurized slightly by recycled gas vapors. The state is looking at requiring new devices at stations to reduce vapors.

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