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14 February 2003 <br /> AGE-NC Project No 98-0432 <br /> Page 4 of 6 <br /> container for transportation under chain-of-custody to McCampbell Analytical Laboratory(MAI), <br /> a California Department of Health Services-certified Laboratory in Pacheco,California Each sample <br /> was analyzed for <br /> ' • Total petroleum hydrocarbons quantified as gasoline and as diesel (TPH-g and TPH-d) In <br /> accordance with EPA Method 8015 Modified, <br /> • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl-tertiary-butyl ether <br /> (MTBE), in accordance with EPA Method 8021B, and <br /> • Fuel additive compounds, including di-isopropyl ether (DIPE), ethyl-tertiary-butyl ether <br /> ' (ETBE), methyl-tertiary-butyl ether (MTBE), tertiary-amyl methyl ether (TAME), and <br /> tertiary-butanol (TBA) in accordance with EPA Method 8260B <br /> 3.0. FINDINGS <br /> ' Soil stratigraphy and ground water elevation,flow direction and gradient were determined from field <br /> data collected in November and December 2002, the contaminant impact to ground water was <br /> 10 quantified by the ground water sample laboratory analytical data <br /> 1 31 STRATIGRAPHY <br /> ' Poorly graded sand or silty sand was encountered from,5 feet to 20 feet,except for an apparent sandy <br /> silt zone encountered at 15 feet in well MW-8 Damp to saturated, generally hard silt was <br /> encountered below 20 feet bsg to total depth,except for an apparently thin,poorly graded sand zone <br /> ' identified betwee 26 and 2$ feet bsg m well MW-7 Ground water was encountered at ` <br /> approximately feet bsg The boring logs are included as Appendix A <br /> �� �X121�3 <br /> 3 2 GROUND WATER GRADIENT AND FLOW DIRECTION <br /> ' The depth to ground water In the monitoring wells ranged from 16 51 to 18 19 feet below the top of <br /> the well casing (btoc) (Table 1) The ground water elevations at the site ranged from 19 64 feet <br /> (MW-7) to 20 05 feet (MW-5) above mean sea level (MSL), the average ground water elevation <br /> decreased 0 5 feet slnt,e the prcvious monitoring event in July 2002 <br /> The ground water flow direction was inferred to be towards the northwest at a gradient of <br /> ' approximately 0 002 ft/ft near the former UST locations, steepening to approximately 0 003 ft/ft at <br /> the northwestern end of the site (Figure 3) <br /> 1 <br /> Advanced GeoEnviron mental,Inc <br /> 1 <br />