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08 August 1997 <br /> AGE-NC Project No 97-0326 <br /> • Page 3 of 4 <br /> concentrations as high as 63 ppm Benzene and MTBE were not detected in any of the samples <br /> analyzed Petroleum hydrocarbons were not detected in samples analyzed from probings B1, B3 or <br /> B4 Analytical results of soil samples are summarized on Table 1 The laboratory report(AAL Batch <br /> No 97-0624-017) and chain-of-custody form are included in Appendix B <br /> S 0 SUMMARY AND CONCLUSIONS <br /> Based upon data collected from the site, AGE concludes the following <br /> • Petroleum hydrocarbons were detected in probing B2 in samples collected at depths of 30 <br /> and 40 feet bsg, indicating that this interval has been impacted by hydrocarbons Field <br /> observations indicated low concentrations of hydrocarbon vapor in soil samples collected at <br /> depths of 15, 20 and 25 feet bsg in that probing The impacted interval could represent a <br /> "smear zone"as a result of fluctuation in ground water elevation of the perched ground water <br /> "aquifer', spreading hydrocarbons in the upper portion over that interval The source of <br /> hydrocarbons has not been determined It is our understanding that the current tanks were <br /> not the original tanks on the property The location of the original tanks is currently <br /> . unknown It is likely that the location of the original tanks, which is currently unknown or <br /> the fuel dispensers area could be the source area(s) of the hydrocarbon impact in that deeper <br /> interval <br /> • Petroleum hydrocarbons were not detected in the sample collected from a depth of 45 feet <br /> in probing B2, defining the vertical extent of impacted soil beneath the USTs <br /> • RelativeIy low concentrations of BTE&X were detected in samples containing petroleum <br /> hydrocarbons, indicating that the release is likely not recent, further enhancing the possibility <br /> of releases from the original tanks <br /> • Saturated conditions were encountered in a sand unit at a depth of 40 feet However, this <br /> water appears to occur in a perched "aquifer", due to dense and only damp silt encountered <br /> at 45 feet bsg First encountered ground water occurs at a depth of approximately 55 to 60 <br /> feet bsg in monitoring wells located approximately 90 east of probing B2 <br /> 6 0 RECOMMENDATIONS <br /> Based upon data collected from the site, AGE recommends the following <br /> • The location of the potential original tanks should be investigated followed by additional <br /> subsurface sampling/analysis in that area <br /> Adtanced GeoEn\ironmentaI,Inc <br /> I <br />