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. 31 August 2005 AGE-NC Project No 96-0232 Page 28 of 30 height of 140 feet and an average MTBE concentration of 0 077 mg/kg were used to estimate the coned elliptical volume of MTBE-impacted soil,for the south segment,a semi-minor axis of 8 feet, a semi-mayor axis of 57 feet, a height of 110 feet and an average MTBE concentration of 0 145 mg/kg were used to estimate the coned elliptical volume of MTBE- impacted soil When the data collected at the site is plotted in both plan view and cross sectional views, the apparent volume of MTBE impacted soil totals approximately 4,433 cubic yards, which yielded a total of approximately 1 54 pounds of MTBE, or an estimated 0 25 gallons of MTBE remaining in soil at the site Volume calculations are included in Appendix L • The mass-volume estimate of MTBE-impacted ground water remaining at the site was determined by splitting the modeled `elbow'-shaped ground water plume into two segments (eastern segment and western segment) The volume of the western impacted ground water segment can be determined by utilizing the formula for an elliptic cone, a semi-minor axis of 10 feet, a semi-mayor axis of 84 feet, a height of 143 feet and an average MTBE concentration of 8 95 µg/1 were used to estimate the coned elliptical volume of MTBE- impacted ground water from the western segment The volume of the eastern impacted ground water segment can be determined by utilizing the formula for an elliptic,cone shaped • cylinder,an average MTBE concentration of 260 µg/l were used to estimate the elliptic,cone shaped cylinder volume of MTBE-impacted ground water from the eastern segment When the data collected at the site is plotted in both plan view and cross sectional views, the apparent volume of MTBE impacted ground water remaining at the site totals approximately 1,082,009 gallons, which yielded a total of approximately 175 pounds of MTBE, or an estimated 0 28 gallons of MTBE remaining in ground water at the site Volume calculations are included In Appendix M • A sensitive receptor survey identified two municipal water wells (CSA Nos 1 & 2)located approximately 1,600 feet and 700 feet, respectively, southeast of the site Domestic water wells were located 150 feet west of the site (Rocky's Restaurant - 14659 North Thornton Road),450 feet west-southwest of the site (Three B's Truck Plaza- 14749 North Thornton Road) and 1,100 feet north-northeast of the site (Flying J's Travel Plaza -15 100 North Thornton Road) No other wells were identified during the sensitive receptor survey • Fate and transport study of the contaminated ground water plume and the contaminated soil plume predicts that CSA Well No 2 was unlikely to be impacted by MTBE from a soil or ground water source,but levels A and B of sentinel well MW-10 potentially may be impacted by low concentrations of MTBE (-3 0 µg/1 and less) • AGE analyzed the risks to a residential adult and child inside a building on the site MTBE was the only COC considered to be a carcinogenic risk,the maximum carcinogenic risk from MTBE was approximately 1 case per million inhabitants for all fate and transport models analysed The hazard index from MTBE was 0 01 or less Advanced GeoEnvironmentnl,Inc