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• 20 January 2000 AGE-NC Project No 95-0173 Page 4 of 14 Sixteen quarterly monitoring events have been conducted at the site since the first ground water monitoring wells were installed During the time period of the ground water monitoring events • TPH-g has been detected in ground water samples collected from wells MW-1 though MW-8 at concentrations as high as 14,000µg11 TPH-d has been detected at concentrations as high as 12,000 ,ug/l TPH-g has been detected in ground water samples collected from soil vapor wells (VW-1 and VW-2) at concentrations of 12,000 µg/l and 4,700 µg/i, respectively • Benzene has been detected in the samples from wells MW-2, VW-1 and VW-2 at maximum concentrations of 1,400µg/l,2,000,ug/l and 30µg/l,respectively Toluene has been detected at a maximum concentration of 61 4g11 in well VW-I Ethylbenzene and xylenes have been detected at maximum concentrations in samples collected from well VW-1 of 720 µg/1 and 800 µg/l, respectively Low concentrations (less then 3 µg/1) or lack of detectable BTEX compounds have been encountered in ground water samples from wells MW-1 and MW-3 through MW-8 • DIPE has been detected in ground water samples from wells MW-3, MW4 and MW8 at concentrations as high as 17 µg/l TBA has been detected in samples from wells MW-1, MW2,MW3, MW-4, MW-8 and soil vapor wells VWl and VW-2 at concentrations as high as 120µg/l, respectively MTBE has been detected in samples from wells MW1 and MW3 at concentrations as high as 6 7µg/1 ETBE and TAME have not been detected in any of the wells sampled TPH-d concentrations exceeded TPH-g concentrations in the samples containing both analytes Figure 3 shows the areal extent of known hydrocarbon-impacted soil Impacted soil is present below the current ground water table, due to historically lower ground water elevations at the site during which time a portion of the unauthorized hydrocarbon release occurred Analytical results of soil samples collected at the site are summarized on Table 1 The analytical results indicate two areas of hydrocarbon-impacted soil, an eastern area south of the AST enclosure on the Jimco site and a western area near the former UST area and transmission shop The eastern area is primarily impacted by diesel fuel hydrocarbons,The former UST area is impacted by diesel fuel compounds, but also is impacted by significant concentrations of gasoline fuel compounds The hydrocarbon-impacted soil plumes of the two areas may be partially comingled Hydrocarbon-impacted ground water in the former UST area has higher average TPH-g TPH-d rations (0 702 - 1 852) compared to ground water in the eastern area (0 089 and 0 104), indicating a greater contribution to ground water of TPH-g in the former UST area The eastern ground water has greater proximity to and an up-gradient position relative to the domestic well on the Jimco site Advanced GeoEnvironmental,Inc