Automatic sensors missed gas leak, MDE official says


An electronic leak detection system apparently was not working when a service station in the Jacksonville area of Baltimore County lost 25,000 gallons of gasoline, according to a state official investigating the incident.

The system of sensors installed in and around the underground fuel tanks and lines at the Jacksonville Exxon station on Jarrettsville Pike failed to react when tested about the time the leak was reported, said Herbert Meade, chief of the oil control program for the Maryland Department of the Environment.

The suggestion that testing showed that sensors failed - disputed by an ExxonMobil Corp. spokeswoman - added to the mystery around one of Maryland's largest underground fuel leaks, as state and company officials worked to keep gasoline from fouling the wells of neighboring homes and businesses. About 7,000 gallons of fuel had been recovered by yesterday morning, officials said.

"We're still trying to figure out what went wrong with this detection unit," Meade said.

But even without it, the state regulator said, the leak should have been noticed much earlier.

Officials believe the leak began Jan. 13, when a contractor performing routine maintenance on the underground fuel storage system unwittingly drilled a pencil-sized hole in the buried fiberglass pipe carrying unleaded regular to the station's gas pumps. Gas dribbled from the hole at an average hourly rate of 28 gallons an hour, based on MDE figures, until ExxonMobil reported it to state environmental officials on Feb. 17.

"It's totally unheard of in today's world, with all the safeguards we have on these underground storage tanks and the records we require to keep," Meade said. He noted that Maryland regulations require station operators to manually check gas inventories daily and promptly investigate any discrepancies. "That it could go on this long has us baffled."

Built in 1984, the Exxon station was equipped with a leak detection system designed to automatically sense a drop in pressure in a fuel line or an unexplained decline in the gas level in the underground storage tank. The system is set up to trigger an audible alarm inside the station and send an electronic signal to a 24-hour call center paid by ExxonMobil and other oil companies to respond to such warnings of leaks or spills.

Federal regulations have required such leak detection systems on many underground fuel storage systems since at least 1998. Environmental Protection Agency officials could not say how often such failures have been reported.

"For the most part, installed correctly and maintained, they should continue to work," said David Iacono of the EPA's mid-Atlantic regional office in Philadelphia. "But any mechanical device is subject to failure."

A contractor for ExxonMobil tested the sensitivity of the station's sensors to a nine-gallon-per-hour leak, "and the system never picked it up," Meade said.

"All these things are manmade, and if it's an electronic sensor, was it calibrated right or was there a malfunction of that sensor?" he asked. "That's something we're looking into."

Betsy Eaton, spokeswoman for ExxonMobil, said she was unaware of the test results the state regulator described. She said the electronic system had been tested by company contractors and passed. The leak was discovered by checking daily fuel inventory records kept at the station, she said, and then confirmed by physically testing the punctured fuel line.

Meade said the automatic detection system at the Jacksonville Exxon was made by a leading national manufacturer, though that model apparently is no longer produced. He said he did not know how many had been installed at Maryland service stations or how many are still in use, but he said he was unaware of any pattern of failures of such systems.

An official with the system's manufacturer, Illinois-based OPW Fuel Management Systems, would not answer any questions about its products, noting the continuing investigation of the Jacksonville leak.

Even without an electronic detection system, a station operator should notice significant losses of gasoline in a day or two at most, regulators say. Under state regulations, Meade said, station operators are required to manually check the level of fuel in their storage tanks every day and compare that with the amount of gas they sold. Any significant inventory discrepancies that persist for seven straight days must be investigated.

An ExxonMobil statement said that in the month before the line puncture was discovered, "contractors were dispatched several times to investigate and did not confirm a leak." Eaton, the company spokeswoman, would not say what prompted the contractors to be dispatched or what they did at the station.

For a time, at least, the contractors and Exxon apparently suspected the inventory discrepancies meant that gasoline sales were not being properly recorded, according to Meade.

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