Test results released yesterday show that a residential well in the Jacksonville area of Baltimore County has been contaminated by significant levels of a gasoline additive, the first such finding since testing was ordered in response to a large gasoline leak there.
That well, among 120 tested since a 25,000-gallon leak was reported in mid-February at the Jacksonville Exxon, shows elevated levels of the gasoline additive methyl tertiary butyl ether, or MTBE.
Herbert Meade, administrator of the oil control program at the Maryland Department of the Environment, said yesterday the well on Hampshire Glen Court, about a quarter-mile east-northeast of the service station, is the only residential water source of those tested to show contamination levels above state guidelines.
Tests found 57 parts per billion MTBE in the residential well in early March, though the level dropped a week later to 32 parts per billion.
Maryland has set an "action level" of 20 parts per billion for MTBE, because the gas additive can be tasted or smelled in drinking water around that threshold. Its human health effects at such levels are unknown, though it has caused cancer in laboratory rats.
John Larrabee, whose well, according to MDE files, showed elevated MTBE levels, said that ExxonMobil Corp. had furnished his household with bottled water and pledged to install a filtration system on the well to remove the contaminants. He said the well had not shown evidence of contamination before the leak. He declined to say more, noting his lawyer's advice.
Meade pointed out that the residential well with elevated MTBE level is out of line from a string of monitoring wells that have collected gasoline since the leak. But as a result of the findings on that well and others, Meade said, the state has ordered ExxonMobil to begin weekly testing of certain wells on Hampshire Glen Court, Robcaste Road, Paper Mill Road and Jarrettsville Pike. Officials had originally ordered tests of residential wells every two weeks.
High levels of MTBE, benzene and other toxic gasoline ingredients have been found in a well used by a nail salon on Jarrettsville Pike just south of the Exxon station, according to test results on file with MDE. The results, showing 4,610 parts per billion MTBE and 15.2 parts per billion benzene, were made available to The Sun yesterday as the result of a Public Information Act request.
Previously, contamination had been reported in a well serving a Bradford Bank branch across the intersection of Jarrettsville Pike and Paper Mill and Sweet Air roads from the service station. MDE records show the bank well, no longer in use, contained 773,000 parts per billion of MTBE and 5,380 parts per billion of benzene. Federal drinking-water safety standards allow for no more than 5 parts per billion of benzene, a human carcinogen.
Low levels of MTBE also have been detected in more than three dozen other residential wells within a half-mile radius of the intersection of Jarrettsville Pike and Paper Mill and Sweet Air roads. But Meade said the trace levels of the gas additive found in many of those wells are too low to be of concern and might stem from previous service station leaks in the area over the past 25 years.
MTBE, added to gasoline for decades as an octane enhancer and later as an oxygenate to reduce air pollution, spreads easily through ground water and can linger there for years.
Meade said gasoline is collecting in several of the 92 monitoring wells the state ordered ExxonMobil Corp. to drill around the station, with most of the fuel in wells along a fault running from northeast to southwest of the station. The state official said those findings, and the limited residential well contamination so far, give him hope that the leaked fuel is largely contained in that underground crevice.
ExxonMobil issued a statement yesterday saying it has recovered about 12,000 gallons of gas, either in liquid or vapor form, from the monitoring wells and the soil.
Glen A. Thomas, president of the Greater Jacksonville Association, said he was not ready to dismiss trace readings of MTBE in residential wells, at least not until subsequent tests show no increases in contaminants.
"We don't know how it's migrating there, and I'm concerned that what we'll find is with weekly testing, the levels may be going up," Thomas said. "I absolutely hope and pray that's not the case."