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On July 9, 1992, Resna published their Summary Report—Assessment of Petroleum Hydrocarbon Contamination of the Groundwater Their scope of work included the installation and sampling of two additional groundwater monitoring wells (MW-2 and MW-3) The highest concentrations of gasoline hydrocarbons in groundwater(1,100 µg11 of Total Petroleum Hydrocarbons [TPH)-as-gasoline and 120 µg11 of benzene) were detected in MW-3, approximately 30 feet north and downgradient of the former USTs From May 8, 1992 to April 27, 1994, the three monitoring wells were monitored and sampled on three different occasions In general, the concentrations of gasoline hydrocarbons in these wells declined, However, by April 27, 1994, the static groundwater level had risen above the top of the screen interval in all three wells This condition does not promote accurate monitoring of groundwater table characteristics On July 8, 1994, Resna published Summary Report/Additional Groundwater Investigation This report documented the installation of two additional groundwater monitoring wells (MW-4 and MW-5) Gasoline hydrocarbons were not detected in groundwater collected from these two new wells The direction of groundwater flow continued to the north-northeast On June 29, 1995, Groundwater Technology, Inc (GTI) published their Environmental Assessment Report documenting the installation of two vapor extraction well nests (VW-1 and VW-2) and two single vapor extraction wells (VW-3 and VW-4) and the pilot testing and modeling of soil vapor extraction Results of this work indicated that an area of approximately 2,055 square feet of soil is impacted by gasoline hydrocarbons to a depth of approximately 70 feet bgs Soil vapor extraction testing indicated an achievable radius of influence of 59 to 75 ffeet and an effective coverage of 80 percent of the impacted soil plume Based on these findings GTI recommended that the site be remediated by soil vapor extraction plus air sparging from MW-1 This active remedial work was never implemented By January 1996, the continued dramatic rise in the groundwater table elevation had exceeded the top of the screen interval in all five groundwater monitoring wells and had entered the screen interval of the two deeper soil vapor extraction wells (VW-1 and VW-2) Coincidentally, from July 1995 to April 1996, groundwater samples collected on four quarterly occasions from the five monitoring wells did not contain detectable concentrations of TPH-as-gasoline ' In August 1996, sampling of the five original monitoring wells was discontinued and the sampling of the two deeper vapor extraction wells (VW-1 and VW-2) was initiated Groundwater samples collected from VW-1 and VW-2 contained detectable concentrations of TPH-as-gasoline (up to . 12,000 µg11), benzene (up to 1,300 µg/l) and Methyl tertiary butyl ether (MTBE) (up to 1,800 µg11) 3