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Historical Background Information: West Clay Properties Page 6 of 7 pressures. Hydrogeologic Unit 5 (HU5) extends from a minimum depth of 166 feet bsg to approximately 191 feet bsg; HU5 is composed primarily of coarse-grained soils including sand and gravelly sand interbedded with minor silt and clayey silt and silt. HU5 is characterized by generally low pore pressures, and may be classified as a flow unit. HU5 was observed in borings CPT-03 and CPT-04 and appears to be laterally continuous beneath the site. Hydrogeologic Unit 6 (HU6) was encountered in CPT-03 from approximately 191 feet bsg to approximately 210 feet bsg. The lateral extent of HU6 is not well defined at the site; CPT-01, CPT-02 and CPT-04 were terminated prior to encountering HU6. HU6 is composed primarily of fine-grained soils including clayey silt and silt. HU6 is characterized by generally moderate to high pore pressures. ANALYTICAL RESULTS OF GROUND WATER SAMPLES Various concentrations of target analytes were detected in each grab ground water sample collected from each sampling interval in soil borings advanced near the former UST No. 3 location(CPT-01 through CPT-03). Analytes of concern were not detected above laboratory reporting limits in grab ground water samples collected from soil borings advanced near the former UST cluster area(CPT- 04 and CHB-01). Former UST No. 3 Location Analytical results of CPT ground water sampling at the former UST No. 3 area are as follows: • HU-2: TPH-g and TPH-d were detected in the ground water sample collected from HU-2 at a concentration of 27,000 micrograms per liter(µg/1)and 8,800µg/l,respectively,in sample CPT03/50-54. BTEX constituents were detected in the same sample at concentrations of 21 µg/l(benzene), 1,000 gg/l(toluene), 1,700µg/l(ethylbenzene)and 6,200µg/1(total xylenes). • HU-3: TPH-g was detected in ground water samples collected from HU-3 at concentration ranging from 110 µg/1 to 190 µg/1 in samples CPT03/74-78 and CPTO1/77-81,respectively. BTEX constituents were detected at concentrations as high as 12 µg/1 benzene (CPTO1/77-81), 27 µg/1 toluene(CPTO1/77-81), 8.6 µg/1 ethylbenzene(CPT03/74-78) and 38 9g/1 total xylenes(CPT03/74-78). TPH-d was not detected in the ground water samples collected from HU-3. • HU-4: TPH-g and TPH-d were detected in ground water samples collected from HU-4 at concentrations as high as 30,000 µg/1 and 25,000 µg/1, respectively in sample CPT02/137-141. BTEX constituents were detected at concentrations as high as 180 gg/l benzene(CPTO1/93.5-97.5),2,300µg/1 toluene(CPT02/137-141), 1,200 µg/1 ethylbenzene Advanced GcoEnvironmental,Inc.