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' 17 February 2004 . AGE-NC Project No 96-0254 ' Page 5 of 10 from wells MW-7 and MW-8 MTBE was detected in the ground water sample collected from MW-7 at a concentration of 84 gg/l MTBE was not detected in the sample collected from well MW-8 Monitoring well logs,soil boring logs and construction specifications are presented in Appendix A Quarterly ground water monitoring has been ongoing at the site since January 2000 TPH-g and TPH-d have only been detected In wells MW-1 and MW-2, their have been no other detections of TPH-g and TPH-d in any of the other ground water samples collected 44fttslnce sampling began Additionally,BTEX compounds have not been detected above laboratory reporting limits in any of the ground water samples collected from the site since sampling began,with the exception of xylene, detected In well MW-1 at a concentration of 8 2 ug/1 in August 2000 MTBE has been detected Intermittently in samples collected from wells MW-3,MW-4,MW-5 and MW-7 at concentrations ranging from,0 51 gg/l to A Vg/l, MTBE has not been detected above laboratory reporting limits ' in any of the ground water samples collected from wells MW-6 and MW-8 since sampling began vm.7l�lU�f MTBE has been detected each quarter I the samples collected from wells MW-1 and MW-2 at concentrations ranging fromgg/l to ;9 µg/l However the average concentration of MTBE each quarter in the water samples collected from wells MW-1 and MW-2 is approximately 1,300 gg/l 3 A graph of MTBE concentrations in wells MW-I and MW-2 since sampling began is presented in ' Appendix B Analytical results of ground water samples are summarized in Tables 4 and 5 - Cross-sections depicting the general lithology in the soil beneath the site is illustrated on Figure 4 Soil boring logs are presented in Appendix A A map depicting the approximate distribution of dissolved MTBE is illustrated on Figure 5 TPH-g,TPH-d and BTEX were not detected in any of the soil samples collected and analyzed at the ' site since assessment activities began Only MTBE was detected in a total of twelve soil samples collected at the site The lateral and vertical extent of Impacted soil has been defined Based on the investigation to date, ground water at the site is only impacted with MTBE at concentrations requiring active site remdl tion T e veru extent of MTBE-impacted ground water has been defined at levels below the`30 Icrograms per lite , he lateral extent of MTBE-impacted ground water has generally been defined�to eve s re u^q fired for site assessment and closure Further assessment may be required to fully define the MTBE-impacted ground water vertically beyond 50 y ' feet bsg 4 0. POTENTIAL IMPACT ON NEARBY SURFACE AND GROUND WATER Typically, ground water would represent the migration medium for contaminants over significant horizontal distances However, sites located in up-gradient or cross-gradient directions from the site are not likely to be negatively Impacted by the sub3 ect property In addition,first encountered ground ' Advanced Geo$nvironmental,Inc