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4 <br /> 03 April 2000 <br /> AGE-NC Project No 98-0511 <br /> Page 4 of 6 <br /> 15 feet to 25 feet bsg In boring B1, damp, silty clay/sandy silt was encountered from depths of <br /> approximately 25 feet to 50 feet bsg <br /> An increase in moisture content was observed in soil samples encountered in each boring at depths <br /> between 15 feet and 20 feet bsg Boring logs are included in Appendix A <br /> 42 FIELD EVIDENCE OF HYDROCARBON-IMPACTED SOIL <br /> Organic vapor was detected utilizing an OVM in soil sample duplicates B 1-10', B I-15', B 1-20' and <br /> B4-15' at concentrations of 2 parts per million (ppm), 3 ppm, 155 ppm and I ppm, respectively <br /> Additionally, an intense petroleum hydrocarbon odor was noted associated with sample B1-20' <br /> 43 GROUND WATER DEPTH AND GRADIENT <br /> The ground water flow direction on the site was determined to be approximately N 75°W at a <br /> gradient of approximately 0 002 ft/ft, based on field data collected from MW-1(EW-1), MW-2, <br /> MW-3, ana MW=4 during the monitoring event of 16 March 1999-, the ground water depth was <br /> approximately 11 feet bsg The flow direction at the site has shifted more than 180 degrees from the <br /> September 1995 monitoring event to the 16 March 1999 monitoring event, the historically <br /> predominant direction has been southerly <br /> 44 RESULTS OF SOIL SAMPLE ANALYSIS <br /> Select soil samples from borings B1, B2, B3, and B4 were submitted for analysis for TPH-g The <br /> laboratory reported TPH-g in samples B1-20' and B1-35' at concentrations of 220 parts per million <br /> (ppm, reported as milligrams per kilogram) and 1 6 ppm, respectively BTEX compounds were <br /> detected in soil sample B1-20' at concentrations as high as 8 7 ppm MTBE was detected in soil <br /> samples BI-20', B1-25,' and B1-30' at concentrations of 31 parts per billion (ppb, reported as <br /> micrograms per kilogram), 51 ppb, and 25 ppb, respectively Analytical results of soil samples are <br /> summarized in Table I Copies of the laboratory reports and chain-of-custody forms are included <br /> in Appendix B <br /> 45 RESULTS OF GROUND WATER SAMPLE ANALYSIS <br /> A total of four grab ground water samples were submitted to DHS-certified laboratories for analysis <br /> 10 TPH-g was detected in ground water samples collected from boring B2 and B3 at concentrations of <br /> Advanced GeoEn<<ronmental,Inc <br />