FORENSIC study at a Northern New Jersey service station: the mixing of old and new gasoline


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In 2000, a client purchased a gasoline service station in northern New Jersey. A few days after receiving possession of the property, he received a letter from a State regulatory agency informing him that an investigation surrounding a leaking waste oil UST was required. He was unaware that a waste oil UST had existed; automotive repairs were not part of his or the previous owner’s business and the previous owner had indicated in writing that there were no environmental problems with the property. The client complied with the directive even though responsibility lay with the previous owner. A monitoring well was installed and laboratory analysis of a ground-water sample revealed elevated concentrations of gasoline constituents such as BTEX and MTBE. Two additional wells were subsequently installed and similar results were found. However, separate-phase gasoline was not detected on the water table.

In 2005, a significant release of regular-grade unleaded gasoline occurred from the existing fiberglass USTs. About 0.5 foot (~0.1 m) of separate-phase gasoline was present on the water table beneath the site and at off-site, downgradient locations. A nearby nursing home and bar had to be evacuated because of gasoline vapours. Samples of separate-phase gasoline were collected from five locations: two on-site and three off-site. TEL was detected in one on-site and all three off-site samples. Furthermore, the TEL concentrations increased in the downgradient location.

Further investigation of historical documents, obtained from the state regulatory agency, revealed that a release of regular-grade leaded gasoline had occurred at this site in the 1970s. A pump-and-treat system had been present in 1978 to 1979 and several thousands of gallons of gasoline had been recovered. However, documental evidence for the appropriate closure of the cleanup was not found.

Review of the separate-phase sample results revealed that the gasoline in four of the five samples was a mixture of regular-grade leaded and regular-grade RFG. The fifth sample was immediately adjacent to the 2005 release and did not contain organic lead. The two gasolines could be distinguished based on the organic leads, and the concentrations of RFG-regulated components, such as oxygenates, benzene and the lack of high vapour pressure compounds such as iso-butane. The increase in TEL concentration off-site was caused by the proportions of new and old gasoline, with the on-site locations containing more new gasoline.

Based on the chemistry of the gasoline, the percentage of RFG gasoline and leaded gasoline could be determined. Based on these percentages, the quantity of gasoline derived from the older release could be calculated.

The case eventually went to court because the previous owner refused to accept responsibility for their portion of the cleanup, even though they had revealed that problems had existed when the sale went through (Dover Gas v. Tallemand Corporation, Morris County Court, 2007).

The data were presented before the judge and just before the closing arguments were presented, a settlement was agreed to, providing the client with the funds to pay for the cleanup.
In this case, the presence of alkyl leads was one of several pieces of evidence used to distinguish a recent gasoline release from a significantly older one.

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