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' 16 May 2002 <br /> AGE-NC Project No 99-0657 <br />' Page 4 of 6 <br />' Hydrological Unit 4 (HU4) extends from approximately 75 feet to approximately 88 feet bsg HU4 <br /> is comprised of silt, clay and stiff fine-grained sediment The interval is characterized by pore <br /> pressure variations from low to moderate pressures <br />' Hydrological Unit 5 (HU5) extends from approximately 88 feet bsg to approximately 95 feet bsg <br /> HU5 is composed of sand and is characterized by low pore pressure <br />' Hydrological Unit 6 (HU6) extends from approximately 93 feet bsg and possibly beyond 128 feet <br /> bsg The upper 10 feet of HU6 is composed of sandy silt and stiff fine grained material However, <br /> sand and silty sand are the dominant soil type in the interval The Interval is characterized by low <br /> pore pressures <br /> Hydrological units are depicted in cross sectional view A-A' (Figure 4) <br /> 33 LABORATORY RESULTS OF GRAB GROUND WATER SAMPLES <br /> • A total of ten grab ground water samples were collected from CPT-1, CPT-2 and CPT-3 and <br /> submitted for laboratory analysis for the above mentioned constituents (Table 1) Ground water <br /> samples were collected from CPT-1 between 40 feet and 44 feet bsg (CPTl-40-44), 64 feet and <br /> 68 feet bsg(CPT1-64-68), 90 feet and 94 feet bsg(CPT1-90-94) and between 121 feet and 125 feet <br /> bsg(CPT1-121-125), CPT-2 between 72 feet and 76 feet bsg(CPT2-72-76), 93 feet and 97 feet bsg <br /> (CPT2-93-97) and between 121 feet to 125 feet bsg (CPT2-121-125), and CPT-3 between 72 feet <br /> and 76 feet bsg (CPT3-72-76), 90 feet and 94 feet bsg (CPT3-90-94) and between 121 feet and <br /> 125 feet bsg(CPT3-121-125) The ground water samples were collected from HU3,HU5 and HU6 <br /> from all three borings and from HU1 from CPT-1 <br /> Ground water sample CPT1-40-44 was collected from HU1 Toluene, xylenes and MTBE were <br /> detected in the sample at concentrations of 2 0 micrograms per liter (µg/1), 2 7 µg/l and 2 2 µg/l, <br /> respectively No other target analytes were detected in sample CPT1-40-44 <br /> Ground water samples CPT1-64-68, CPT2-72-76 and CPT3-72-76 were collected from HU3 <br /> TPH-g was detected in sample CPT2-72-76 at a concentration of 130 µg/l TPH-d was detected in <br /> samples CPT2-72-76 and CPT3-72-76 at concentrations of 63 µg/1 and 170µg/l,respectively BTEX <br /> compounds were detected in sample CPT2-72-76 at concentrations of 8 8 µg/1 benzene, 18 µg/1 <br /> toluene, 1 9 µg/1 ethylbenzene and 7 9 µg/1 total xylenes, total xylenes were detected at a <br /> concentration of 0 96 µg/1 in the sample from CPT3-72-76 MTBE was detected in sample <br /> CPT2-72-76 at a concentration of 1 3 µg/1 <br /> Ground water samples CPT1-90-94, CPT2-93-97 and CPT3-90-94 were collected from HU5 <br /> TPH-g was detected in samples CPT2-93-97 and CPT3-90-94 at concentrations of 770 µg/l and <br /> Advanced GeoEnvironmental,Inc <br /> I <br />