Historically, there has been a gas station since 1937 at the LaMountain site at Route 20 and North Main Street. ExxonMobil operated the station until 1954, and continued to own the underground tanks until 1996, when it sold the tanks to LaMountain.
In 1986, a tank failed a routine tightness test. There was an explosion during the repair due to vapors in the tank; however, there was no significant release at that time because the tank was empty, or nearly so. In May 1990, Methyl Tertiary-Butyl Ether (MTBE) was discovered in nearby private wells. There is no record of any catastrophic release.
Working under the oversight of Massachusetts Department of Environmental Protection (MADEP), ExxonMobil has conducted soil, soil vapor, groundwater and surface water sampling both on and off site for more than two decades. We also have conducted extensive on-site remediation including soil excavation, groundwater dewatering, and operation of groundwater treatment/soil vapor extraction systems.
During redevelopment of the site in 2006, the station was demolished and more than 2,500 tons of contaminated soil were removed and some 70,900 gallons of petroleum-impact groundwater were extracted. A CVS pharmacy now occupies the current property.
What is MTBE?
Methyl Tertiary-Butyl Ether (MTBE) is an oxygenate, and oxygenates help gas burn more cleanly and reduce air pollution. In 1979, the federal government approved the use of MTBE in gasoline. Initially, MTBE was used sporadically to replace lead in gasoline.
The federal Clean Air Act Amendments of 1990 created a program that mandated the use of oxygenates in gasoline in locations with poor air quality and various states, including Massachusetts, chose to participate in this program. Congress knew at this time that it was effectively mandating the use of MTBE to comply with the requirements because there was an insufficient supply of other oxygenates to meet the nationwide demand for gasoline.
In the northeast, MTBE was the only feasible oxygenate available for use. Another option, ethanol, was not available in sufficient quantity at that time to allow the demand for gasoline to be met. Ethanol was more expensive for the consumer as it cannot be transported in pipelines.
MTBE worked as intended, significantly improving air quality. MTBE blending has resulted in a 105,000-ton reduction of smog pollutants per year – the equivalent of removing 16 million cars from the road, or more than every car in New Hampshire, Vermont, Maine, Massachusetts, Connecticut, Rhode Island and part of New York, combined.
Government Acceptance of and Support for MTBE
MTBE’s benefits to air quality came with known risks to groundwater. MTBE is very soluble in water, often travels farther than other gasoline constituents, and can be more difficult to remediate than gasoline releases that do not contain MTBE. The Environmental Protection Agency (EPA) was aware of these groundwater concerns before it approved MTBE’s use in the Clean Air Act Reformulated Gasoline program.
Even a decade later, EPA continued to support the use of MTBE: “EPA supports the continuation of the use of oxygenates, such as MTBE, in fuels under such programs as the reformulated gasoline program. EPA believes that there are significant air quality and public health benefits as the result of the use of oxygenated fuels.”
Similarly, in 1999, the Northeast States for Coordinated Air Use Management, of which Massachusetts is a member, stated in a joint study that “[t]he aggregate public health benefits [gasoline with MTBE] provides by reducing air pollution substantially outweigh potential adverse public health impacts from exposure to increased levels of MTBE in the air and water. Tens of millions of northeast residents benefit from reduced exposure to mobile source air toxins…”
The Environmental Protection Agency can provide further information on MTBE and its usage.
More MTBE Information
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