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09 May 2003 • AGE-NC Project No 99-0559 Page 5 of 7 Clay is the predominant on-site soil type,smaller Intervals of stiff,fine-grained soil,silty clay,clayey silt and silt In addition, a thin (approximately 1-foot thick), a laterally discontinuous layer of cemented sand was identified in CPT-1 at 125 feet bsg and a similar-size silty sand was Identified in CPT-2 at 155 feet bsg Soil types in HU5 are coarser towards the north and southwest,and include clayey silt, silt, stiff, fine-grained soil and sandy silt, with a finer-grained, predominantly clay interval at between approximately 125 and 150 feet bsg, a 5-foot thick, laterally discontinuous sand layer was identified,at approximately 140 feet bsg in CPT-7 HU5 is characterized by pore pressure variations from low to moderate pressures, with occasional, moderately high pressures associated with silty and stiff, fine-grained soil Hydrological Unit 6 (HU6) extends from approximately 165 feet bsg to total depth of the deepest I CPTs (CPT-6 and CPT-8) and between 165 and 170 feet bsg in multi-level well MW-5 The unit consists of silty sand and gravelly sand and is characterized by a very low pore pressure If laterally continuous beyond CPT-6, CPT-8 and MW-5, this unit should be characterized as a flow unit 3 3 LABORATORY RESULTS OF "GRAB" GROUND WATER SAMPLES lie A total of nineteen discrete,grab ground water samples was collected from HU2,HU4,Upper HUS and Lower HU5 and submitted for laboratory analysis for the constituents listed in Section 2 2 (Table 1) HU2 Samples CPT4-70,CPT5-70,CPT6-70,CPT7-70 and CPT8-70 were collected from HU2,the upper most occurrence of ground water from the CPTs TPH-g was detected only in samples CPT4-70 and CPT8-70 at concentrations of 1,100 micrograms per liter (µg/l) and 150 µg/l, respectively The I BTEX compounds toluene and xylenes were detected in sample CPT8-70 at concentrations of 1 4 µg/1 and 1 1 µg/1, respectively The fuel additive MTBE was detected in CPT4-70, CPT6-70 and CPT8-70 at a maximum concentration of 1,500 µg/l (CPT4-70), ETBE were detected in CPT4-70 and CPT8-70 at a maximum concentration of 3 4 µg/1 (CPT4-70), and 1,2-DCA was detected in CPT8-70 at 6 2 µg/1 In addition, the cleaning solvent TCE was detected in samples CPT5-70 and CPT8-70 at concentrations of 1,700 µg/I and 10 µg/1, respectively, CPT-5 and CPT-8 are the westernmost borings of the investigation HU4 Samples CPT4-90, CPT5-100, CPT6-100, CPT7-100 and CPT8-100 were collected from HU4 TPH-g was detected in samples CPT4-90,CPT6-100 and CPT8-100 at concentrations of 2,000µg/1, Advanced GeoEnvironmental,Inc