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' 05 November 2003 - <br /> • AGE-NC Project No 99-0657 <br /> Page 3 of 4 <br />' One or more BTEX compounds were detected in water samples collected from wells MW-1,MW-2, <br /> MW-4, MW-5, and MW-6 with maximum concentrations of 350 µg/1 benzene(MW-6), 27 ug/l <br /> toluene (MW-1), 64 pg/l ethylbenzene (MW-6) and 670 µg/1 xylenes (MW-4) <br />' MTBE was detected in water samples collected from wells MW- - <br /> p 1 through MW 6 at a maximum <br />' concentration of 2,200 gg/1(MW-6) TAME was detected in the water samples collected from well <br /> MW6 at a concentration of 9 4 pg/I <br /> 1,2-DCA was detected in water samples collected frorn MW-1, MW-4 and MW-6 at a maximum <br /> concentration of 83pg/1 (MW-6) <br /> No other fuel additives were detected at or above laboratory detection limits in the ground water <br /> samples analyzed The analytical results of water samples collected in April 2003 are summarized <br /> on Table 2 The laboratory report (CTEL Lab Project No CT214-0307029), QA/QC report and <br /> chain-of-custody form are included in Appendix C <br /> 4.0. SUMMARY AND CONCLUSIONS <br /> The following conclusions were drawn from the results of this investigation <br /> • The ground water elevations ranged from 4 32 to 4 97 feet above MSL Ground water is <br /> inferred to be flowing toward the southwest with an average ground water gradient of <br /> I0 006 feet/feet The ground water elevation at the site is the lowest level recorded to date, <br /> with a average decrease of 1 35 feet between the April 2003 and July 2003 monitoring <br /> events <br /> • The highest concentrations of dissolved hydrocarbons occurred in monitoring wells MW 1, <br /> MW-4 and MW-6, which are located down-gradient of the UST area A general decreased <br /> I of all dissolved hydrocarbons occurred in monitoring wells MW-2 Iso-concentration maps <br /> depicting the approximate distribution ofdissolved TPH-g,benzene and MTBE are presented <br /> in Figures 4, 5 and 6 <br /> • Concentrations of dissolved TPH-g, TPH-d, BTEX and fuel additives have remained <br /> relatively stable and or decreased in MW-1, MW-2, MW-3, MW-7, and MW-8 <br /> I Concentrations of dissolved TPH-g, TPH-d,BTEX and fuel additives increased moderately <br /> in MW-4, MW-5, and MW-6 The coincidence of these two trends may likely indicate an <br /> active migration of the dissolved phase hydrocarbon plume Therefore,to prevent additional <br /> migration, Interim corrective action should be proposed <br /> I <br /> IAdvanced GeoEnvironmental,Inc <br /> i <br />