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High and low groundwater levels below ground surface ' Between September 7, 2000 and December 19, 2002, depth to groundwater measured on a quarterly basis in the four on-site monitoring wells ranged from a maximum depth of 80 60 feet (below top of casing) and minimum depth of 73 29 feet Tabulated results of all sampling and analyses ' The cumulative soil sample analytical results are summarized in Table 1, and the cumulative groundwater analytical results are summarized in Table 3 ' Dissolved concentrations of TPH-as-gasoline, BTEX, 1,2-DCA, EDB, and the fuel oxygenates DIPE, EwTBE, TAME, TBA have never been detected in groundwater samples collected from the ' four groundwater monitoring wells at the site, with the exception of a single detection of 0 55 gg/I of xylenes to well MW-4 in December 2001 MTBE was detected only in monitoring well MW-3 on four occasions between December 20, 2000 and September 18, 2001, at a maximum concentration of 2 4 gg/I MTBE has not been detected in any of the monitoring wells above the detection limit of 0 5 µg/l, during the last five monitoring events dating back to December 17, M 2001 No gasoline compounds, including MTBE, additional fuel oxygenates, 1,2-DCA, and EDB have ever been detected in the on-site domestic water supply well Maximum concentrations remaining at the site in soil and groundwater are tabulated in the Appendix B Summary in Appendix C of this report Vertical and lateral concentration contours of contaminants found initially, and those remaining in soil and groundwater, both on and off site ' Hydrocarbons in Sod Sources of gasoline hydrocarbons in soil include the southern end of the western dispenser island and the north end of the former UST (Tank 2) The soil samples collected in these areas and the concentrations of TPH-as-gasoline in these soil samples are shown on Figure 4 All of the soil sample analytical results are summarized in Table 1 ' At the southern end of the western dispenser island, soil sample PL-4 5 contained 190 mg/kg of TPH-as-gasoline, 0 6 mg/kg of benzene, 10 mg/kg of toluene, 3 0 mg/kg of ethylbenzene, 14 mg/kg of xylenes, 130 mg/kg of MTBE The vertical extent of impacted soil beneath the western . 12