Leaking underground storage tanks and pipelines have recently become one of the most widespread and talked about environmental problems. Across the country, service station gasoline storage tanks are being tested for leaks and replaced as either necessary or precaution dictates. While the total number of underground storage tanks is unknown, it is estimated to be in the vicinity of 1.4 million tanks and, of these tanks, between 10 and 30% are thought to have leaked gasoline into the ground.1 For a leak to be considered a contamination problem, at least 1,000 gallons of gasoline has usually been spilt. Leaks of up to 270,000 gallons have been reported, and leaks in the range of 20,000 to 50,000 gallons are not uncommon. Most of this gasoline has contaminated the subsurface soils and groundwater, and in many cases poses a major threat to drinking water supplies, since a single gallon of gasoline can render 1 million gallons of water unsuitable for consumption.