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' 23 March 2001 • AGE-NC Project No 95-0130 ' Page 5 of 6 ' approximately 120 feet bsg(total depth) Conversely, less-permeable fine grained, silty clay and clayey silt was encountered at depths between 25 and 30 feet bsg, 64 and 70 feet bsg, 80 and 85 feet bsg and between 106 feet and 112 feet bsg Variable llthology Including silty fine I sand and sandy silt was encountered at all other depths Geologic cross sections D-D'and E-E' were generated from CPT data collected at P-10, P-11 and P-12 and depict general lithology beneath the site in cross sectional view (Figures 3 and 4, respectively) IAGE interprets the CPT data to Identify five potential hydrogeologic units informally Identified as "First Zone"ground water(located 12 to 34 feet bsg), "Second Zone" ground ' water (located 36 to 65 feet bsg), "Third Zone" ground water (located 70 to 80 feet bsg), "Fourth Zone" ground water (located 95 to 107 feet bsg) and `Primary Aquifer Zone" ground water (located 116 to at least 121 feet bsg) It is not known how effectively the intervening fine grained intervals hydrologically separate the informal hydrogeologic units though petroleum hydrocarbon-Impact has migrated through or around them Geologic cross sections D-D'and E-E'were generated from CPT data collected at P-10, P-11 and P-12 and depict the informal hydrogeologic units and petroleum hydrocarbon concentrations beneath the site in cross sectional view(Figures 5 and 6, respectively) • Dissolved constituents of concern detected at P-10, P-11 and P-12 were TPH-g, TPH-d, ITPH-mo,BTEX and MTBE, concentrations of TPH-g, TPH-d, TPH-mo, BTEX and MTBE were variable with depth, low concentrations of 1,2-DCA were detected in the Primary Aquifer Zone Constituents of concern detected at P-10, P-11 and P-12 are depicted in the informal hydrogeologic units in cross sectional views GC'and D-D'(Figures 5 and 6) • Generally, the greatest hydrocarbon-impact was reported from grab water samples collected at P-11 in Second Zone ground water(36 to 65 feet bsg), Fourth Zone ground water(95 to 107 feet bsg) and Primary Aquifer Zone ground water(116 to at least 121 feet bsg), and at P-12 in First Zone, Second Zone, Fourth Zone and Primary Aquifer Zone ground water ' • The laboratory reported the TPH-g sample chromatograms from P-11 and P-12 as having significant unmodified or weakly modified gasoline, this implies that only a minimal amount Iof hydrocarbon degradation occurred in these samples • The laboratory reported the TPH-d sample chromatograms from P-11 as having significant gasoline, diesel (unmodified or weakly modified) and oil range compounds in Second Zone, Fourth Zone and Primary Aquifer Zone ground water samples, the laboratory reported the TPH-d sample chromatograms from P-12 as having significant diesel range compounds, this I Implies that a gasoline, diesel and oil release may have occurred in the area of P-11 and has migrated to depth I I IAdvanced GeoEnvironmental,Inc