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11 February 2002 <br /> AGE-NC Project No 99-0559 <br />' Page 9of10 <br /> The sample collected from 135 feet (CPT2-135 — middle HU5) contained TPH-g at 2 4 mg/kg, <br /> BTEX compounds were detected in at concentrations as high as 0 51 mg/kg toluene (benzene was <br /> at 0 16 mg/kg) MTBE was detected at a concentration of 16 pg/kg <br /> Other fuel additives were not detected at or above laboratory reporting limits in any of the soil <br /> samples The laboratory reports (MAI Lab I D 65278 through 65280) and chain-of-custody forms <br />' are presented in Appendix C Analytical results for the CPT soil samples collected are depicted in <br /> Figure 8 Analytical results of the CPT soil samples are summarized in Table 2 <br />' 4.0. SUMMARY AND CONCLUSIONS <br />' Based upon data collected during this investigation, AGE concludes the following <br />' • Generally,the subsurface of the site is comprised of alternating thick intervals of fine grained <br /> material and thin to thick coarse grain units A significant unit of concern,HU4,was a thick <br /> poorly graded sand to silty sand layer encountered at approximately 92 to 105 feet bsg CPT <br />' computer-generated boring logs are included in Appendix A <br /> • HUl was impacted by TPH-g, benzene and MTBE in the former UST area and only by <br /> MTBE south and west of the former UST area <br /> I • HU4 was impacted by TPH-g, benzene and MTBE in the former UST area and toward the <br /> west and was slightly impacted by MTBE (<5 0 pg/l) south of the former UST area <br /> • The upper HU5 (130 feet bsg)was impacted in the former UST area by TPH-g,benzene and <br /> MTBE The unit was less impacted south of the former UST area(TPH-g<100 µg/l) This <br /> I unit was not impacted west of the former UST area, down-gradient <br /> • The lower HUS, at 150 feet, was significantly impacted by TPH-g, benzene and MTBE in <br /> the former UST area,yet was not impacted by TPH-g and BTEX south or west of the former <br /> UST HUS at 150 feet was slightly impacted by MTBE (<5 0 gg/l) south of the former UST <br /> area <br /> • The vertical extent of dissolved TPH-g and benzene does not extend to 130 feet bsg in the <br /> area of CPT-1 or to 60 feet bsg in the area of CPT-3 The vertical extent of dissolved TPH-g <br /> and benzene has not been determined in the area of CPT-2, adjacent to the former UST area <br /> and extends to the lower HU5 at 150 feet bsg <br /> Dissolved MTBE does not extend vertically to 130 feet bsg in the area of CPT-1 The vertical <br /> I extent of dissolved MTBE has not been determined in the areas of borings CPT-2 and <br /> CPT-3 The concentrations of dissolved MTBE detected in the former UST area increases <br /> . with depth, and highest MTBE detection in boring CPT2, the former UST area, was in the <br /> I <br /> Advanced GeoEnvironmental,Inc <br />