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' 25 March 2002 AGE-NC Project No 97-0326 Page 3 of 9 ' • Oxygenated volatile organics -di-isopropyl ether(DIPE), ethyl tertiary-butyl ether(ETBE), MTBE, tertiary-amyl methyl ether(TAME), tertiary butanol (TBA), methanol and ethanol in accordance with EPA Method 8260B ' • Ethylene dibromide (EDB) and 1,2 dichloroethane (1,2 DCA) in accordance with EPA Method 8260 I ' • Volatile organics (vocs) by GCIMS (full-scan 8260) ' 3.0. RESULTS ' The computer-generated CPT hthologic data interpretation was integrated with previous subsurface soil descriptions to refine the subsurface geological model, the hydrocarbon impact to ground water and soil was quantified by laboratory analysis of the grab ground water and soil samples, as ' presented below 31 STRATIGRAPHY Based on the findings from the CPT soil bonngs and soil composition data acquired to previous ' borings. (Figure 2), cross sections A-A' and B--B' were constructed, which depict general lithology beneath the site (Figures 3 and 4) The sediments above 70 feet below surface grade (bsg) are generally laterally discontinuous and tend to be fine-grained,predominantly consisting of alternating ' clayey silts silty clays and clays The coarsest sediment was in a 10-foot thick silt and sand wedge near the western edge of the site which lenses out towards the west, east and south (see Figure 4) ' Below 70 feet bsg is a CPT-defined cyclical sequence of laterally continuous sand layers alternating with finer-grained sediments The laterally continuous sand layers occur at an approximately 30-foot ' interval The uppermost sand at approximately 80 feet bsg is the thinnest, at approximately 4 feet, the thickest layer, at approximately 110 feet bsg, is approximately 12 feet thick As mapped, the sequence appears to be nearly horizontal (see Figures 3 and 4) ' AGE has developed a preliminary subsurface model of the site soil stratigraphy comprised of seven informal zones, a vadose (unsaturated)zone and six hydrological units Hydrological units may be ' defined as significant vertical intervals of soil having significant lateral extent and inferred to have similar hydrologic characteristics (i e hydraulic conductivity, transmissivity, etc ) over its vertical and horizontal extent A `flow unit' may be defined as a hydrologic unit characterized by ' significantly greater hydraulic conductivity values than overlying and underlying units A flow unit • ' Advanced GeoEnvironmentai,Inc r