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09 May 2003 <br /> AGE-NC Project No 99-0559 <br /> Page 7 of 7 <br /> • TPH-g was detected is ground water samples collected in HU2, HU4 and Upper HU5, the <br /> maximum concentration was 2,000 µg/1 in HU4 <br /> I BTEX compounds were detected only in HU2 <br /> • Fuel additives were detected in all hydrologic units The highest concentrations were detected <br /> in HU4,MTBE was detected in HU4 at a maximum concentration of 2,600 µg/l,ETBE and <br /> TAME were detected at 25 µg/l and 5 6µg/1,respectively,and TBA and DIPE were detected <br /> at 630 µg/1 and 18 µg/l, respectively However, only TBA was present in Lower HU5, at a <br /> I concentration of 180 µg/1 <br /> • HU4 is a thick poorly graded sand layer encountered at approximately 90 to 110 feet bsg <br /> MTBE is apparently migrated laterally within this unit, especially off-site towards the west <br /> I • Dissolved MTBE extends off-site past all current sampled locations The concentrations of <br /> dissolved MTBE decreased away from the site, except to the west at CPT4, the highest <br /> concentration of MTBE detected off-site <br /> • The vertical extent of dissolved TPH-g, benzene and MTBE does not extend to below <br /> • 130 feet bsg <br /> i • The solvent TCE was detected in HU2 and HU4 in the offsite borings CPT-5 and CPT-8 <br /> (Figure 2), at a maximum concentration of 1,700 µg/1 The TCE appears to originate from <br /> an off-site source, since TCE was not detected in CPT borings (e g , CPT-4 and CPT-6) <br /> closer to the site <br /> 5.0 RECOMMENDATIONS <br /> Based on the findings from this investigation, AGE recommends an additional CPT investigation <br /> to define the lateral extent of MTBE-impacted ground water west of the site <br /> 6.0. LIMITATIONS <br /> Our professional services were performed using that degree of care and skill ordinarily exercised by <br /> environmental consultants practicing in this or similar localities The findings were based mainly <br /> I upon analytical results provided by an independent laboratory Evaluations of the geologic/hydro- <br /> geologic conditions at the site for the purpose of this investigation are made from a limited number <br /> of available data points (CPT data, and soil and ground water samples), and subsurface conditions <br />' may vary away from these data points No other warranty, expressed or implied, is made as to the <br /> professional recommendations contained in this report <br /> Advanced GeoEnvlronmental,Inc <br /> I <br />