ABSTRACT
A major problem facing public health and the environment is the release of petroleum from leaking underground storage tanks (UST) into soil and its migration into groundwater aquifers. Aquifers are a vital natural resource supplying more than https://www.w3.org/1998/Math/MathML"> 50 % https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429080050/6559e41b-64b9-4256-96a3-5980cbb6d757/content/eq1068.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> of the U.S. population with water for domestic use (1). Public health may be threatened with exposure to groundwater containing petroleum due to its toxic constituents, particularly benzene, which is classified as a human carcinogen, but also by less toxic constituents including toluene, ethyl benzene, and xylene (BTEX). The U.S. Environmental Protection Agency (EPA) estimated that 100,000-400,000 USTs are currently leaking (2), mainly due to corrosion of the older bare-steel tanks (1). The potential threat exists for substantial increases in contaminant release, with several million UST systems in use in the United States containing petroleum or hazardous chemicals (1). It is estimated that service station gasoline tanks alone could be losing 11 million gal/year of product (3). The potential threat of leaking USTs was illustrated from a recent groundwater contamination survey in South Carolina which showed a dramatic increase in groundwater-contaminated sites due to leaking USTs. The number of reported groundwater-contaminated sites in South Carolina rose from 60 in 1980 to 3619 in 1998 (4). The sharp increase coincided with the enactment of UST control legislation requiring increased groundwater monitoring efforts. Of the reported 3619 contaminated groundwater sites, 3028 were attributed to leaking USTs (4). Petroleum products accounted for more than https://www.w3.org/1998/Math/MathML"> 88 % https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9780429080050/6559e41b-64b9-4256-96a3-5980cbb6d757/content/eq1069.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> of all chemical contaminants reported at these contaminated sites (4), and air sparging/soil vapor extraction (AS/SVE) is well suited to address this type of contamination.
