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20 September 2000 <br /> • AGE-NC Project No 97-0333 <br /> Page 9of11 <br /> g impacted soil ranged between 20 and 25 feet bsg(Figures 14 and 15) Low levels of TPH-g <br /> were detected at 30 feet bsg in borings MW-1 and MW-4 The lateral extent has not been <br /> defined to the north, south and east <br /> • Low concentrations of BTEX were detected in borings MW-1, MW-2 and MW-4 BTEX <br /> compounds were detected as deep as 30 feet bsg in the three borings Laterally, the BTEX- <br /> impacted soil plume has not been fully defined to the north, south or east of the site The <br /> vertical extent of the impacted soil has not been fully defined, although contaminant <br /> concentrations have declined sharply at depths as great as 40 feet bsg <br /> ' MTBE was detected in soil samples collected from bonngs MW-1, MW-2 and MW-3 The <br /> highest MTBE concentrations occurred at 15 feet bsg in borings MW-1 and MW-2 The <br /> vertical extent of MTBE-impacted soil appears to extend to depths in excess of 30 feet bsg <br /> (Figures 14 and 15) The lateral extent of MTBE-impacted soil has not been defined to the <br /> north and south, the vertical extent of MTBE-impacted soil is unknown at the site Based on <br /> data previously collected from P-4, the vertical extent of MTBE-impacted soil underlying <br /> ' the former UST pat extends to at least 40 feet bsg <br /> • Low concentrations of TAME were detected in the 20-foot and 30-foot samples collected <br /> '• from boring MW-1 <br /> The plume appears to have descended from the former UST pit to depths in excess of 40 feet <br /> ' bsg and to have spread laterally within a fine to medium sand interval generally between 20 <br /> and 40 feet bsg The approximate models are shown in cross sectional views A-A ' and B-8 ' <br /> in Figures 14 and 15, respectively <br /> ' The results of the microbial enumeration and physicochemical analysis indicated that <br /> hydrocarbon-degrading microorganisms were detected as high as 6,400 CFU per gram The <br /> 1 laboratory indicated that the physicochemical conditions at the site were well within the <br /> range necessary to support microbial growth and bioremedial activity <br /> • Based on the guide flow to Evaluate Altei native Cleanup Technologies Fol UST Sites <br /> ' (October 1994) published by the United States Environmental Protection Agency (EPA) <br /> Office of I1STs, intrinsic permeability values between the magnitude of 10' and 10' are <br /> generally adequate for soil vapor extraction (SVE) technology (Exhibit IT& Inottisic <br /> ' Pernieabilm, And SVE Effectiveness) with respect to gasoline-impacted sites Based on <br /> information gained through laboratory analysis, the average permeability at the site was <br /> between 3 x 10 ' (MW-5 at 25 feet bsg) and 2 x 10 ' (MW-5 at 15 feet bsg) The laboratory <br /> ' analysis indicated permeability conditions at the site should be adequate for SVE technology <br /> III, iiidings of(hc R0y 2000 ground \,�atcr inonitonng event results arc. as €'olloe�s <br /> i <br /> �dianrcd(It(If 11vn011111tnf a iii, <br />