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I ' 12 January 2005 • AGE-NC Project No 97-0326 1 Page 7 of 11 ' apparently moderate to high pore pressures in more clayey intervals and low pore pressures in stiffer fine-grained intervals ' Hydrogeologic Unit 4 (HU4) extends from between 95 and 100 feet to approximately 120 feet bsg and consists of approximately 10 feet of fine-grained sediment overlying approximately 10 feet of sand, the lower half of the sand interval is gravelly sand HU4 is characterized by very low to low ' pore pressure Hydrogeologic Unit 5 (HU5) extends from approximately 120 to approximately 135 feet bsg It is ' a predominantly fine-grained interval, silts, and a 2-foot thick sand lense in the western half of the survey area transitions to silty clay in the eastern half The lateral variation in soil types is reflected in the pore pressures, which tend to be dominantly low in the western half and moderate to high in ' the eastern half of the area Hydrogeologic Unit 6 (HU6) extends from approximately 135 feet to 150 feet bsg This interval ' consists dominantly of sand and gravelly sand and is characterized by very low to low pore pressure Hydrogeologic Unit 7 (HU7), 150 feet bsg, is a black clay recovered at total depth in wells MW-8 and MW-9 ' Copies of the boring logs from this investigation are included in Appendix B ' 3 3 ANALYTICAL RESULTS OF SOIL SAMPLES Twenty-nine soil samples were submitted for laboratory analysis for the constituents listed in Section ' 2 14 The analytical results for each informal zone are listed below Vadose Zone TPH-g and BTEX compounds were detected in soil samples collected from borings ' MW-8 and MW-9, at a maximum concentration of 1,600 milligrams per kilogram(mg/kg)TPH-g, 0 12 mg/kg benzene, 0 29 mg/kg toluene, 17 mg/kg ethylbenzene and 85 mg/kg xylenes in sample MW9-30 MTBE was the only fuel additive detected in the analyzed sample, at a maximum ' concentration of 0 15 mg/kg (sample MW9-20) HU1 TPH-g was detected in soil samples collected from borings MW-8 and MW-9, at a maximum concentration of 3,000 mg/kg in samples MW9-35 and MW9-40 BTEX compounds were detected from borings MW-8 and MW-9 at maximum concentrations of 4 2 mg/kg benzene and 19 mg/kg toluene in sample MW9-35 and 37 mg/kg ethylbenzene and 176 mg/kg xylenes in sample MW9-40, ' only benzene at a concentration of 1 1 mg/kg was detected in boring MW-7(sample MW7-48) Fuel additives were not detected in HU1 ' Advanced GeoEnvironmental,Inc