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I ' 27 October 2000 AGE-NC I Project No 95-0143 Page 5 of 6 Iconcentrations have dropped signficantly during the last two quarters Analytical results are summarized on Table 5 Analytical results of historical soil vapor samples are summarized on Table 6 The laboratory reports (MAI sample Nos 44456, 44457, 47023, 47024, 48967 and 48968) and chain-of-custody forms are included in Appendix C 3 5 MASS OF HYDROCARBONS REMOVED A total of approximately 8,352,000 cubic feet of soil vapor was extracted from the site between 29 I August 2000 and 30 September 2000 Approximately 44 kilograms, or 17 gallons, of gasoline were removed from the site during the same time period Calculations for the mass of hydrocarbons removed are included in Appendix E I 4.0. SUMMARY/CONCLUSIONS Based upon data collected from the site, AGE concludes I • Ground water elevation decreased approximately 1 59 feet between May 2000 and August 2000 Ground water elevation was above the screened interval of the monitoring wells and slightly below the screened interval of the vapor extraction wells The exposed portion of the I screened interval in the five vapor extraction wells was within a silty layer and just above a sandy layer The inferred ground water flow direction remains variably toward the north to northeast at the site IPetroleum hydrocarbons were detected in five of the nine wells sampled at concentrations ranging from 150 µg/1 (MW-6) to 120,000 µg/l (MW-3) Concentrations of TPH-g and BTEX were significantly higher m MW-7 and lower in MW-10 compared to results from the second quarter monitoring event This may be the result of a slight shift to the west of the ground water contamination plume Measurable free product was not encountered during the I August 2000 monitoring event Fuel oxygenates were not detected in ground water samples collected during the August 2000 monitoring event 1,2-DCA was detected in MW-14 at a concentration of 4 6 µg/1 • TPH-g was detected at an average concentration of 180 µg/1 over the quarter in the soil vapor samples from the intake to the SVE unit Significant decreases in soil vapor concentrations I have occurred since early April 2000 The drop in soil vapor concentrations coincides with an increase in ground water elevation Historically,average depth to ground water at the site has been well below the elevation of the SVE's horizontal extraction wells (approximately I 13 feet bsg) During the May 2000 ground water monitoring event, average depth to ground water was 13 14 feet bsg in MW-9, MW-14 and MW-I5, the closest monitoring wells to the northern horizontal well field Elevated ground water levels appear to degradate the Advanced GcoEnviironmenta4Inc