The hunt for the dangerous gasoline additive MTBE, which is contaminating wells in the Upper Crossroads area of Fallston, is expanding in geographical extent, in testing techniques and in sources suspected as a cause of the problem.
Some residents of the area are not satisfied with the progress of the state testing program and have hired private contractors to examine their wells.
When Darrin Ryan of Fallston had his well tested privately for methyl tertiary butyl ether, or MTBE, he was alarmed by the findings. Ryan's Hampton Court home is about 1 1/2 miles southeast of the Exxon service station at Routes 152 and 165 that environmental officials believe is partly responsible for the problem
A July 9 examination found that his water had MTBE levels of 20 parts per billion, the reading at which the state recommends corrective action be taken to remove contamination by the possible carcinogen.
MTBE was discovered in wells in the area within a half-mile radius of the service station early last month, according to Maryland Department of the Environment officials. Completed analysis indicates that at least 127 wells in the area are tainted with MTBE. Ten wells tested in the state's program had MTBE levels of 20 parts per billion or higher, the state's action level.
Richard McIntire, spokesman for the MDE, said people with levels above 20 parts per billion should contact the MDE and the Harford Health Department.
Wallace Waynick of Burgundy Drive, more than two miles southeast of the station, said his well tested positive for the gasoline additive last month with a level of 0.6 parts per billion.
"With MTBE in my well, because I'm outside of the half-mile radius, I'm left out in the cold," he said.
McIntire said many people outside the half-mile radius had MTBE readings below 20 parts per billion.
"We understand and recognize that the material shouldn't be present," he said, "but the mere presence shouldn't necessarily cause a panic."
Michael O'Brien, who lives outside the half-mile radius, said he has lost faith in the Health Department and state environmental department.
"There are great big properties outside the half-mile radius," he said. "Why are we not testing more to the east?"
Yolande Norman, chief of remediation for the MDE's oil control program, said the state will examine the preliminary data for leads on where to test next. "We want to start from the known and move to the unknown," she said.
The sampling that the MDE now requires is based on the trends in MTBE findings so far, Norman said.
Herbert M. Meade, administrator for the oil control program, said such trends have expanded testing down Baldwin Mill Road to include the Orchard Lanes community and down Green Road, including Hunting Ridge Court to the Upper Crossroads Church at Crystal Lane.
Exxon Mobil has installed carbon filtration systems on 120 wells, environmental officials said, and a new testing procedure launched last week seeks evidence of vapor leakage at the Exxon station in the effort to track the source of the problem. No leak had been found at the station through the original testing procedures, but Meade acknowledged last week, "We'd not even thought about vapors."
MDE officials are also looking for other sources that could be affecting the area farther from the station. These include all areas where gasoline is used, including home heating oil tanks, auto repair shops and former gas stations. One source that MDE has ruled out is the Colonial Pipeline, which carries petroleum products and runs north of Upper Crossroads. Colonial officials reported three weeks ago that they had no leaks.
MDE spokesman Jeff Welsh said Colonial uses a continual release detection system, adding that the pressure they use is so great, they would immediately know of any leaks.
"With [the pipeline], there's no such thing as a small leak," Welsh said.
"If there is another source, who is looking for it?" Ryan asked MDE officials at a public hearing Tuesday night. Days later, Ryan said he still had "absolutely no idea what MDE is doing."
Health officials are seeking to allay public fear as the investigation continues.
Andrew Bernstein, Harford County's health officer, compared the amount of exposure received from one part per billion of MTBE with one second in 31.7 years or one penny out of 10 million pennies.
"It's a minuscule amount," he said, adding that residents should not confuse the exposure they receive by drinking water with MTBE levels with everyday exposure to the chemical. MTBE, he explained, can be found in air and rain.
A map of the Upper Crossroads MTBE testing site is available at: www.mde.state.md.us/Programs/landProgram s/Oil_Control/RemediationSites/index.asp.