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09 April 2002 <br /> AGE-NC Project No 95-0141 <br />' Page 3 of 13 <br /> Concentrations of 1,2-DCA were detected in ground water samples collected from each of the eight <br /> monitoring wells as high as 310 µg/l <br /> I Petroleum hydrocarbons have been detected in each sample collected from the deep well (MW-6) <br /> since it was Installed in November 2001 Based upon the detection of petroleum hydrocarbons, it <br /> appears that analytes of concern have migrated vertically to at least 65 feet bsg in soil and ground <br /> water Furthermore,the horizontal extent of"deep"contamination has not been determined Figures <br /> 3, 4 and 5 depict the horizontal extent of hydrocarbon-impacted in first encountered ground water <br /> Figures 6 and 7 depict general lithology beneath the site <br /> Ground water at the site has risen significantly since monitoring wells MW-1 through MW-5 were <br /> $'n Y g <br /> Installed As a result, the wells are now "drowned" and may not be providing samples that are <br /> Irepresentative of the actual impact to ground water In addition,wells MW-1,MW-2 and MW-5 may <br /> provide a vertical pathway for contamination from a sandy interval located approximately 25 to 30 <br /> feet bsg to a deeper sand interval located approximately 50 feet bsg and extending to at least 65 feet <br /> bsg (Figures 6 and 7) Boring logs recorded during the installation of the MW-1, MW-2 and MW-4 <br /> are included in Appendix B <br /> 2 3 GROUND WATER DEPTH AND GRADIENT <br /> During the most recent monitoring event In February 2002, the average depth to ground water was <br /> approximately 20 feet bsg During past monitoring events at the site, ground water flow direction <br /> has generally been toward the east, varying from northwest to northeast <br /> I3.0. SCOPE OF WORK <br /> AGE proposes to advance one CPT boring at the former UST location to determine the vertical <br /> Iextent of hydrocarbon-Impacted ground water Monitoring wells MW-1, MW-2 and MW-4 will be <br /> abandoned and replaced by Installing four "cluster" ground water monitoring wells to define the <br /> I horizontal extent of ground water contamination north, northwest, southwest and southeast of the <br /> former UST location One "deep" ground water monitoring well will be installed to define the <br /> horizontal extent of hydrocarbon-Impacted groundwater east ofthe former UST location below first- <br /> encountered ground water In addition,AGE proposes installation of a ground water extraction well <br /> near the former UST location and installation of two temporary observation wells to facilitate <br /> performance of ground water extraction feasibility testing Proposed CPT boring and well locations <br /> are included on Figure 2 <br /> IAdvanced Geognvn•onmentai,Inc <br />