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r I i I <br /> I <br /> I w <br /> 14 September 2004 <br /> AGE-NC Project No 96-0235 <br /> i <br /> Page 7 of 8 <br /> I <br /> 3 3 2 Former UST Cluster <br /> ` Analytes of concern were not detected in ground water samples collected from the soil borings <br /> advanced near the former UST cluster area Analytical results of ground water samples are included <br /> in Tables 1 and 2 Copies of the laboratory reports (CTEL Laboratory IDs 0406-054-7 through <br /> 0406-054-9) are included in Appendix C Sampling locations and analytical results of ground water ' <br /> samples are illustrated on cross sections A-A' and B-B'+(Figures 9 and 10) <br /> I4.0. SUMMARY AND CONCLUSIONS <br /> h Based on the findings from the CPT and ground water investigation, AGE concludes " <br /> • Dominantly fine-grained soil consisting of silt, clayey silt, silty clay and clay were <br /> encountered at depths from the near surface to approximately 210 feet bsg Significant sand <br /> amts with variable silt to gravel were encountered between 10 feet and 40 feet bsg, 62 feet <br /> to 90 feet bsg and 165 feet to 191 feet bsg The shallow sand unit (20 feet to 40 feet bsg) <br /> appears to have limited lateral continuity Lesser, thin, laterally discontinuous sand units <br /> were encountered at approximately 50 and 100 feet bsg at the southern UST No 3 area <br /> t <br /> • Grab ground water samples collected from soil borings advanced near the former UST No 3 <br /> ` location contained detectable concentrations of TPH-g, TPH-d and BTEX constituents at <br /> depths as great as 180 feet bsg Due to refusal, additional samples could not be collected <br /> from greater depths In addition, detectible concentrations of target analytes were reported <br /> by the laboratory in grab ground water samples collected from soil borings advanced down- <br /> gradient of the former UST No 3 location at depths ranging from 74 to 78 feet bsg and 178 <br /> 'to 182 feet bsg Neither the vertical nor the deep lateral extent of petroleum hydrocarbon- r <br /> impacted ground water has been defined around the former UST No 3 location <br /> • TPH-d was detected at depths as great as 180 feet bsg Generally,longer-chain hydrocarbons <br />' (TPH-d)do not have a propensity to migrate vertically through groundwater The laboratory 1 <br /> report indicates that detected TPH-d concentrations are mostly in the gasoline range and may <br /> explam the significant diesel concentrations at such depths - - <br />'r E Target analytes were not detected above laboratory reporting limits in grab ground water <br /> samples collected from the former UST cluster area to depths as great as 182 feet bsg In <br /> addition, target analytes were not detected above laboratory reporting limits in grab ground <br /> f water samples collected'from bonng CHB-01, located down-gradient from the former UST <br /> cluster location The vertical extent of impacted ground water appears to be defined at the <br />' UST cluster location, the lateral extent is not defined to the north and southwest <br /> I i <br /> r w <br /> Advanced GeoEnvironmental,Inc <br /> I <br /> + , i <br /> 1 <br /> 4 <br />