U.S. Water News Online
ARLINGTON, Va. -- Most methyl tertiary butyl ether (MTBE) found in groundwater occurs in monitoring wells, which are not sources of public drinking water, says the Oxygenated Fuels Association. Monitoring wells are often used to monitor the soil and groundwater immediately next to gasoline storage tanks.
MTBE and other fuel components are sometimes found in groundwater when gasoline leaks from underground storage tanks at gas stations, according to James Davidson, a hydrogeologist and president of Alpine Environmental, Inc., a consulting firm in Fort Collins, Colorado.
In California, more than 1,740 public drinking water wells were tested for MTBE. Less than half of 1 percent of the drinking wells tested had MTBE levels above state and/or federal health advisories, according to the California Department of Health Services. The State of California's Interim Action Level for MTBE is 35 parts per billion and the U.S. Environmental Protection Agency's draft water health advisory is 70 parts per billion. To put this in perspective, 1 part per billion is approximately a single drop of liquid in a 10,000-gallon tanker truck, Davidson said.
"Most shallow monitoring wells are intentionally sited and used to detect and monitor soil and groundwater contamination from a known point source such as service stations or gasoline pipelines," added John Kneiss, director of health and product stewardship for the Oxygenated Fuels Association (OFA). "These monitoring wells are not, and never were designed to be used as a source of drinking water."
Monitoring wells provide an early warning before contamination spreads to public drinking wells. "Since MTBE moves at the same rate as groundwater, it is detected first which indicates there is a likely gasoline leak in the area," Davidson said. "Gasoline leaks release known toxics such as benzene, toluene, and xylene."
MTBE, an oxygenate derived from natural gas, has been used in gasoline since 1979 as an octane enhancer and in 1992 to reduce vehicle emissions. Fuel containing MTBE helps to clean the air by reducing the amount of harmful pollutants released into the atmosphere.
Davidson has extensive experience investigating and remediating petroleum releases and has been involved with more than 400 contamination projects across the country and internationally since 1984. Previously, Davidson worked as a corporate hydrogeologist for Shell Oil Co., and as a consultant for other petroleum companies.
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