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01 March 2002 <br /> AGE-NC Project No 95-0130 <br /> Page 5 of 10 <br /> custody form, stored in a chilled container and transported under chain-of-custody to a DHS-certified <br /> laboratory for analysis for <br /> • TPH-g by EPA Method 8015M, <br /> • BTEX and MTBE by EPA Method 8020, and <br /> • Methanol, ethanol, EDB, 1,2-DCA,TBA,DIPE,ETBE,TAME, and MTBE by EPA Method <br /> 8260 Modified <br /> 3.0. FINDINGS <br /> ISoil descriptions were utilized to construct geologic cross sections of the site and field data was <br /> utilized to select soil samples for laboratory analysis Petroleum hydrocarbon-impact to selected soil <br /> samples and ground water samples was assessed and quantified by laboratory analysis <br /> 3 1 SOIL TYPE DISTRIBUTION <br /> Based on continuous-core observations of soil data collected from MW-6 and MW-7 (Appendix B), <br /> poorly graded, fine to medium SAND/silty SAND was generally observed at depths between 30 to <br /> 35 feet bsg, 50 to 55 feet bsg, 68 to 77 feet bsg, 127 to 130 feet bsg and 138 to 145 feet bsg <br /> Fine-grained, clayey SILT was generally observed from at depths between surface grade and 30 feet <br /> bsg, 45 and 50 feet bsg, 95 and 100 feet bsg and between 137 feet and 142 feet bsg, variable <br /> lithology consisting of sandy, clayey silts and silty sands were observed at all other depths Saturated <br /> soil was encountered at a depth of 40 feet bsg, boring logs are included in Appendix B <br /> 32 HYDROLOGIC UNITS <br /> Based on continuous core soil data collected from MW-6 and MW-7, cone penetrometer testing <br /> (CPT)results and comparison with soil descriptions from bonngs previously advanced on the site, <br /> AGE has developed a preliminary subsurface model of the site soil stratigraphy comprised of five <br /> informal zones, a vadose (unsaturated) zone and four hydrological units Hydrological units may be <br /> defined as significant vertical intervals of soil having significant lateral extent and having similar <br /> hydrologic characteristics (i e hydraulic conductivity, transmissivity, etc ) over its vertical and <br /> horizontal extent AGE has informally identified the five informal zones in geologic cross sections <br /> . B-B'and G-C'(Figures 3 and 4) as having significant intervals of apparently porous to semi-porous <br /> grained soil separated by significant intervals of finer-grained, less permeable soil, geologic cross <br /> Advanced GeoEnvi ron mental,Inc <br />