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' 10 September 2004 <br /> AGE-NC Project No 04-1129 <br />' Page 5 of 7 <br />' 2 4 2 Ground Water Depth and Gradient <br /> Y <br /> Based on ground water data collected during the four quarters of ground water monitonng,the depth <br /> I` to ground water at the site has ranged from approximately 33_5 feet to 36 7 feet below the tops of <br /> the well casings(btoc) The ground water flow direction near the former gasoline UST has generally <br /> been toward the southeast with an average gradient t <br /> 01 foot/foot <br /> I <br /> 3.0. ASSESSMENT OF PETROLEUM HYDROCARBON-IMPACTED SOIL AND <br />' I' GROUND WATER FROM SOIL BORINGS <br /> Between May 2002 and May 2003, six soil bonngs were advanced at the site for collection of sort <br />' and grab ground water samples and installation of three ground water monitoring wells (MW-1 <br /> through MW-3) <br />' 3 1 HYDROCARBON-IMPACTED SOIL <br />'. The greatest concentration of petroleum hydrocarbon-impacted soil was encountered in soil borings <br /> B-5 and MW-1 between depths of 5 feet and 20 feet bsg(Table 1),petroleum hydrocarbons were not <br /> detected in soil samples collected from soil borings PB-2,PB-3,PB-20,MW-2 and MW-3 General <br />' lithology, soil sample locations and the vertical and lateral extent of petroleum hydrocarbon- <br /> impacted soil are depicted in cross sectional views A-A' and B-B' (Figures 3 through 6), the <br /> Iapproximate areal extent of adsorbed petroleum hydrocarbon-impacted soil is depicted on Figure 2 <br /> Based on the vertical and lateral extent o fhydrocarbon-imp acted soil,the apparent maximum volume <br /> of petroleum impacted soil beneath the site is approximately 4,949 cubic yards (Appendix D) A <br /> mass-volume'calculation of TPH-d yields approximately 1,781 gallons of TPH-d in the remaining <br /> impacted soil at the site (Appendix D) <br /> I <br /> 3 2 HYDROCARBON-IMPACTED GROUND WATER <br />' Relatively low concentrations of TPH-g and BTEX constituents were detected in a grab groundwater <br /> sample collected from boring PB-2,located near the former UST area However,analytes of concern <br />' were not detected in ground water samples collected from monitoring wells MW-1 through MW-3 <br /> during the monitoring and sampling period Analytical results of ground water samples are <br /> summarized in Table 2 <br /> Advanced GeoEnvironmental,Inc <br />