Storage Tanks

Underground and aboveground storage tanks and transmission pipelines are another cause of groundwater pollution. Among all underground storage tanks and pipelines, gasoline and home oil fuel tanks probably contribute the most to groundwater contamination. These tanks and pipelines are subject to corrosion and structural failures with subsequent leaks that introduce a variety of contaminants into groundwater. Leakage is particularly frequent from bare steel tanks that are not protected against corrosion. Even if a leakage is small, it can pose a significant threat to groundwater quality.

Gasoline and petroleum products contain hydrocarbon components such as benzene, toluene, and xylene that are highly soluble and mobile in groundwater and can be hazardous to humans if consumed. One gallon of gasoline is enough to render one million gallons of groundwater unusable based on U.S. Environmental Protection Agency (EPA) drinking water standards (Noonan and Curtis 1990). In addition, vapors and immiscible compounds trapped in the pore spaces of the unsaturated zone continue to feed groundwater with contaminants as precipitation moves into and through the subsurface or as the groundwater table fluctuates (Dietz 1971; Van Dam 1967).

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