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1 lie 5.0 RESULTS OF INVESTIGATION ' 5.1 Subsurface Conditions Subsurface lithology encountered during this latest phase of investigation was dominated by silt and clay from the ground surface to approximately 50-55 feet bgs, with the exception of minor sand lenses encountered during the drilling of well NFW6 at approximately 15 feet bgs and 45 feet bgs ' Although no soil samples were collected from those specific depths in wells MW5, MW7, or MW8, minor sand lenses were encountered at various depths in previously installed wells Underlying the ' fine grained soil, a water bearing unit consisting of well graded sand extended to depths up to 65 feet bgs Although several minor sand lenses were encountered between the depths of ' approximately 65 feet bgs and 95 feet bgs in the vicinity of well MW 1, these sand lenses do not appear to be laterally significant based upon continuous sampling conducted during the drilling of well MW9(B), which encountered only fine grained materials (primarily silt with some clay) from 70 feet bgs to approximately 122 feet bgs Well graded sand with gravel, poorly graded sand, and ' clayey sand was encountered in well MW9(B) from approximately 122 to 130 feet bgs, and sandy lean clay was encountered from approximately 130 to 135 feet bgs, the maximum depth explored Lines of section for stratigraphic cross sections are presented on Figure 4 and the cross sections themselves are presented on Figures 5 and 6 No Petroleum odors were noted in any of the borings However, FID readings of approximately 100 parts per million (ppm) were noted in the samples collected at 60 and 65 feet bgs in boring MW6 Soil boring locations are presented on Figure 3 Well completion details and soil boring logs are included in Appendix I ' The post-development depth to groundwater in site wells varied between the depths of 59 and 60 feet bgs The potentiometric surface as measured in the shallow zone monitoring wells (MW1- MW8) on October 25, 2000 ranged from —27 84 to —28 16 feet below mean sea level (MSL) The potentiometric surface in well MW9(B) was —28 80 feet MSL, which implies a slight ' downward vertical gradient exists between the shallow and 120-foot aquifers Groundwater elevations are summarized in Table 7 Groundwater beneath the site on October 25, 2000 flowed generally northeasterly with a ' 10 data gmundze/tuteburWreports/mud_has weltrepoFtdoe