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17 April 2003 <br /> AGE-NC Project No 97-0333 <br /> Page 6 of 7 <br /> ' 3 2 FIELD EVIDENCE OF HYDROCARBON-IMPACTED SOIL <br /> No hydrocarbon odors were noted in soil `samples collected from MW-8 at depths between 15 and <br /> t 165 feet bsg Hydrocarbon odor observations are recorded on the boring logs contained in <br /> Appendix B <br /> 33 HYDROLOGIC UNITS <br /> ' Based on soil data collected from MW-8, previous cone penetrometer testing (CPT) results and <br /> comparison with soil descriptions from borings previously advanced on the site,AGE has developed <br /> a preliminary subsurface model of the site hydrostratigraphy comprised of five Informal zones, a <br /> t vadose(unsaturated) zone and four hydrological units(Figures 3,4 and 5) Hydrological units may <br /> be 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 /> C-C',E-E'and F-F'(Figures 3,4 and 5)as having significant intervals of apparently porous to semi- <br /> lie <br /> porous grained soil separated by significant intervals of finer-grained, less permeable soil <br /> ' 4 0. SUMMARY AND CONCLUSIONS <br /> The implications ofthe September,October and November 2002 multi-level well installation results <br /> ' are as follows <br /> • Between 26 September and 09 October 2002, multi-level ground water monitoring wells <br /> MW-7 through MW-13 were installed on-and off-site Generally, AGE installed six screen <br /> intervals at each multi-level well and identified the screen intervals as intervals A,B, C, D, <br /> E and F at depths between 30 and 35 feet bsg (A),60 and 65 feet bsg(B), 85 and 90 feet bsg <br /> (C), 115 and 120 feet bsg (D), 140 and 145 feet bsg (E) and 165 feet and 170 feet bsg (F) <br /> ' Monitoring well details are summarized in Table 2 and depicted in Figures 13 through 19 <br /> • Cross sectional views GC',E-E'and F-F'were generated from previous investigation and <br /> ' sampling data collected from MW-8 and depict general lithology beneath the site in cross <br /> sectional view(Figures 3,4 and 5,respectively) Generally,less permeable, sandy,silty clay <br /> and clayey silt is apparent at the site at depths between 50 and 60 feet bsg and intermittently <br /> ' between 90 and 127 feet bsg More permeable lithology consisting of poorly to well graded, <br /> unconsolidated, silty, fine to coarse-grained sand was observed at all other depths (Figures <br /> 3, 4 and 5, respectively) Boring logs are Included in Appendix B <br /> ' • No hydrocarbon odors were noted in soil samples collected from MW-8 at depths between <br /> 15 and 165 feet bsg Saturated soil was encountered in MW-8 at a depth of 30 feet bsg <br /> ' Advanced GeoEnvironmental,Inc <br />