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ri <br /> 12 February 2002' <br /> AGE-NC Project No 97-0312 ' <br /> - <br /> Page 4of18 = t <br /> I seven soil samples analyzed by EPA Method 8260 at concentrations as high as 2 7'mg/kg <br /> Other oxygenates were not detected <br /> a{I' <br /> Refenng to Figure 6, petroleum hydrocarbons were not detected in soil samples collected from 'r <br /> bonngs B3, B4, B5, B6, B12, B16, B23, B25, B28, B29, UST-2 and UST-3, delineating the <br /> maximum potential lateral extent of impacted soil Low concentrations of BTEX were detected in <br />' bonngs B8, B13, B22, B27 and UST4 Bonngs UST-1 through UST-5, B14 through B19 and B21 <br /> through B29 were advanced to depths below the vertical extent of impacted soil (Figures <br /> 7 through 12), defining the vertical extent of impacted soil at these locations The greatest <br /> concentrations of hydrocarbons were detected beneath the former UST locations Higher <br /> concentrations were also detected in the shallow piping soil samples and in borings UST-1 and UST- <br /> 5 The plume of impacted soil at the site has an estimated northeast-southwest diameter of <br /> approximately 180 feet, an northwest-southeast diameter of approximately 70 feet and appears to } <br /> extend downward more than 80 feet bsg The calculated volume of hydrocarbon-impacted soil is <br /> approximately 10,000 cubic yards (Appendix B) The approximate lateral and vertical extent of <br /> impacted soil is illustrated in Figures 6 through 12 <br /> ISThertical extent of impacted ground water near the former UST and dispenser area has not been <br /> delineatQ� In addition, the grab ground water sample collected from soil boring B 17, located east <br /> of UST-1 and UST-5, contained elevated concentrations of TPH-g, TPH-d and MTBE Additional <br /> I investigation of these areas is required to fully define the vertical and lateral extent of hydrocarbon- <br /> impacted ground water at the site <br /> 3.0. SCOPE OF WORK t <br /> L S , <br /> The results of UST removal activities and extensive soil and ground water investigations performed <br /> to date show that soil and ground water at the site have been impacted by petroleum hydrocarboris „ <br /> and fuel oxygenated compounds To further define the lateral and vertical extent of hydrocarbon- <br /> impacted ground water, AGE proposes to install a cluster well down-gradient from the location of <br /> soil boring B`17 The cluster well,will be installed to address the two coarse-grained zones identified <br /> I dunng installation of UST-1 Pnor to installing the cluster well,UST-1 will be abandoned to prevent <br /> potential vertical`migration of impacted ground water between the two intervals The EHD has <br /> " directed by letter(dated 09 October 2001)that remediation feasibility testing be performed at the site <br /> to determine an appropriate remediation system for both soil and ground water (Appendix A) ' <br /> To determine the most appropriate remediation system for the site,AGE proposes to conduct a soil+, <br /> vapor extraction feasibility test, a ground water extraction' feasibility test and an ozone sparge <br /> feasibility test at the site In addition, AGE will evaluate soil excavation and removal as a fourth <br /> • alternative for remediation AGE proposes to install four SVE wells to perform an 8-hour SVE <br /> I r t <br /> Y Advanced GcoEnvironmental,Inc <br /> 4 <br /> ti <br />