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I I24 June 2005 • AGE-NC Project No 98-0534 ' Page 4 of 6 • Benzene, toluene, ethylbenzene and total xylenes (BTEX) and methyl tertiary-butyl ether (MTBE) in accordance with EPA Method 8260B, and • Oxygenated compounds - di-isopropyl ether (DIPE), ethyl tertiary-butyl ether (ETBE), MTBE, tertiary-amyl methyl ether (TAME), tertiary butanol (TBA), 1,2-dibromoethane (EDB) and 1,2-dichloroethane (1,2-DCA) in accordance with EPA Method 8260B y 3.0. FINDINGS ' Ground water elevation, flow direction and gradient were determined from field data collected on 28 January 2004, the contaminant impact to ground water was assessed from the laboratory data 3 1 GROUND WATER ELEVATION AND GRADIENT ' The relative elevation ofg round water in each well was calculated by subtracting the depth to ground water from the relative casing elevation (Table 1) The depth to ground water on 28 January 2005 ' • ranged between 7 72 and 9 09 feet below the tops of the well casings, relative ground water elevations ranged between 1 94 feet (MW-5) to 4 01 feet (MW-1) below mean sea level (MSL) Presently the water table is at the top of the screened interval of the wells P1 v�Q�0 iJG The potentiometnc surface was represented by a northeast-trending ridge at the former UST area 11 ' The ground water was inferred to be flowing southeast towards well MW-1 and locally to well MW-4 north of the former UST area, at a gradient that ranged from 0 046 ft/ft at the former UST area to between 0 005 ft/ft and 0 02 ft/ft along the southern portion of the site The ground water ' profile and gradient are depicted on Figure 3 1 ' 3 2 STRATIGRAPHY Generally,gray or green-gray, dry to moist silt or clay was encountered from approximately 5 to 30 ' feet bsg A layer of significant sand was encountered at 30 feet bsg,this layer was comprised of three feet of coarse sand which was saturated A layer of approximately four feet of medium grained sand with fines was encountered below the upper coarse sand layer A thin silt layer was observed below ' the upper sand,while a seven to eight foot thick sand layer was encountered from 37 to 45 feet bsg Silt with varying amounts of clay (plasticity) was observed to approximately 65 feet bsg A poorly graded sand was observed at 65 feet at the bottom of the soil boring(Appendix A) Site stratigraphy ' is presented in cross sectional view on Figure 4 • 1 Advanced GeoEnvironmental,Inc