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• 29 December 2003 <br /> AGE-NC Project No 95-0103 <br /> Page 3 of 5 <br /> 25 BOREHOLE ABANDONMENT <br /> At the conclusion of soil boring activities, the borings were permanently sealed to prevent vertical <br /> migration of contaminants Under EHD oversight, the borehole was backfilled with cement slurry <br /> from the total depth to surface grade <br /> 3 0. FINDINGS <br /> Soil descriptions from boring logs CB6, CB7 and CBS, supplemented with soil descriptions from <br /> previous site investigations,were utilized to construct the site geological model, laboratory analysis <br /> of the soil samples was utilized to assess the petroleum-hydrocarbon impact on soil Analytical data <br /> from the soil analysis are presented below and in Tables 1 through 2, soil boring log and copies of <br /> the field measurements and laboratory reports are included in Appendices B and C <br /> 3 1 STRATIGRAPHY AND DEPTH TO GROUND WATER <br /> . Silty clay was generally encountered from a depth of approximately 5 feet to between 15 and 17 feet <br /> bsg A gray, generally silty fine sand was distributed at depths between 15 and 27 feet bsg on-site, <br /> off-site,the sand was generally distributed at depths between 20 and 30 feet bsg Alight green to blue <br /> green clay was usually encountered beneath the sand Ground water was encountered at depths <br /> ranging from 17 feet to 20 feet bsg, once ground water was encountered, a hydrocarbon odor can <br /> be detected <br /> I <br /> Soil borings are depicted in Appendix B A stratigraphic cross section with the distribution of <br /> hydrocarbon impacted soil is depicted in Figure 3 <br /> 3 2 HYDROCARBON-IMPACTED SOIL <br /> Forty-two soil samples were analyzed for TPH-g,BTEX,and MTBE,selected samples were analyzed <br /> for fuel additives <br /> • TPH-g was detected in twelve of the soil samples analyzed at concentrations as great as <br /> 550 milligram per kilogram (mg/kg), in soil sample CBI 0-20 (17 feet bsg vertical depth) <br /> • TPH-g was not detected in soil samples collected above a vertical depth of 17 feet bsg, and <br /> except for sample CB7-36 (31 feet bsg vertical depth) near the northeastern corner of the <br /> building,TPH-g was not detected in soil samples collected below a vertical depth of 24 feet <br /> bsg <br /> • <br /> Advanced GeoEnvirownental,Inc <br />