Underground storage tank releases, contamination

Remediation of Sites Contaminated by Underground Storage Tank Releases... 

The third cleanup program, also authorized by the RCRA, addresses contamination resulting from leaks and spills (mainly petroleum products) from underground storage tanks (USTs). This law has compelled cleanup activities at many UST sites. By February 1999, over 385,000 releases had been reported, 327,000 cleanup projects initiated, and 211,000 projects completed. 

On May 17, 1993, two underground storage tanks (USTs) at the Artesia Yard failed tank-tightness tests. A representative of the New Mexico Environment Department (NMED) confirmed the release on August 2, 1993, when the tanks were removed (Fig. 2). In addition to removing the tanks and associated piping, which were the primary sources of contamination, the excavation contractor removed approximately 100 yards of hydrocarbon-contaminated soil from the former tankhold. 

Secondary containment enclosures other than double-wall construction have been widely used to control vessel leaks. Bunkers built around underground storage tanks are common examples of this approach to preventing releases to the atmosphere and into the soil around the tank, to minimize potential for ground water contamination. Use of tank-high dikes with covers or roofs is another example of secondary containment that limits postrelease emissions. 

Benzene is released to water from the discharges of both treated and untreated industrial waste water, leachate from landfills and other contaminated soils, gasoline leaks from underground storage tanks, and from accidental spills during marine transportation of chemical products (CDC 1994 Crawford et al. 

Product le ng from an underground storage tank will migrate downward until it encounters the water table, where it will then flow with the groundwater, leaving a long trail of contaminated soil. Above the water table, some product will be absorbed on the soil particles and in the pore space between the soil particles. If the soil is later saturated by water, product stored in the pore spaces may be released, causing a reappearance of the free product and movement of the material into previously unaffected soil. 

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