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23 March 2001 AGE-NC Project No 97-0301 Page 9of11 MW-7,located approximately 35 feet east of the former UST area at depths of 30 and 40 feet ' bsg TPH-g concentrations increased with depth at MW-7(Table 1,Figure 8) The lateral and vertical extent of impacted soil has not been defined northeast, east and southeast of MW-7 • Low concentrations of BTEX were detected in borings MW-5 and MW-7 in soil as deep as ' 70 feet bsg Laterally,the BTEX-impacted soil plume has not been fully defined northeast and southeast of MW-7 BTEX-impacted soil extends to 70 feet bsg,beyond which BTEX ' concentrations sharply decline • 1,2-DCA was detected in the 30-foot sample collected from boring MW-7 ' 0 Generally, the TPH-g/TPH-dBTEX plume beneath the former UST area extends to at least 40 feet bsg, however it appears the contaminants detected at depths in excess of 70 feet bsg and contaminants detected at MW-7 could have originated from another source due to the ' increasing concentrations with depth at MW-7 and due to an Intermediate interval of non detect soil samples collected at 45, 55 and 60 from MW-1 and P-1 The approximate models are shown in cross sectional views A A', B-B'and C C'in Figures 6, 7 and S, respectively ' 0 The results of the microbial enumeration and physicochemical analysis indicated that hydrocarbon-degrading microorganisms were detected as high as 25,000 CFU per gram The laboratory indicated that the physicochemical conditions at the site were well within the range necessary to support microbial growth and bioremedial activity ' Based on the guide How to Evaluate Alternative Cleanup Technologies For UST Sates (October 1994) published by the United States Environmental Protection Agency (EPA) Office of USTs, intrinsic permeability values between the magnitude of 10' and 10-$ are t generally_adequate for soli vapor extraction (SVE) technology (Exhibit ITS Intrinsic Permeability And SVE Effectiveness) with respect to gasoline-impacted sites Based on Information gained through laboratory analysis, the average permeability (hydraulic ' conductivity) at the site was between 5 x 10' cm/sec (MW-5 at 25 feet bsg) and 2 x 10' cm/sec(MW-5 at 45 feet bsg), hydraulic conductivity is converted to intrinsic permeability utilizing the conversion factor of 102 x 10' cm/sec which yields Intrinsic permeability ' values between 5 1 x 10" cm2 and 2 04 x 10-11 cm2 The laboratory analysis Indicated permeability conditions at the site should be marginal to Ineffective for SVE and IAS technology The implications from the December 2000 ground water monitoring event are as follows ' The ground water elevation at the site was within the screened Intervals of wells MW-1, MW-2, MW-3, MW-4, MW-6 and MW-7 which yield samples fully representative of ' shallow ground water conditions, ground water elevation was approximately 50 feet above the screened Interval of MW-5 and yields a sample representative of deeper water conditions Advanced GeoEnvironmental,Inc I