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' Geo loguaC?ecFtncc'Inc Page 6 Soil&Groundwater Investigation Report ' J M Equipment Project No 507 2 June 9, 1999 NOTE It should be noted that one of Independent Trucking monitoring wells has been damaged and needs to be repaired Once this has been completed and any additional wells installed, a licensed surveyor will survey all of the monitoring wells at this site ' A site-specific groundwater gradient and bearing was calculated from the depth to water measurements taken during the groundwater monitoring The gradient was 0 0027 ft/ft ' flowing N410E The average groundwater elevation of this site was —6 99 feet below mean sea level Monitoring Well 1, 5 and 8 were used to determine gradient ' Several inconsistencies were noted in the groundwater elevations at the site • MW-9 and MW-6 showed the same groundwater elevations If these two wells were used to calculate the gradient direction it would yield a gradient that is contrary to the groundwater elevations observed in the other wells At the time these wells were drilled ' there was a large pool of standing water around MW-6 This may have caused and artificial mounding of the groundwater at that location + The groundwater elevation in MW-2 is significantly higher then that observed in any of the other wells The well box of this well has been crushed and it is possible that the casing has been pushed down since it was first surveyed • If MW-I, MW-5 and MW-9 are used to calculate the groundwater gradient, the same gradient direction is calculated but a slope of 0 0016 ft/ft is generated To clear up these inconsistencies, a Iicensed surveyor will survey all the wells associated with this site into an accurate benchmark elevation after the well box on MW-1 is replaced Table 3 in Appendix A is a summary of water level elevations, gradient slopes and bearings Figure 3 is a groundwater gradient map for the site 3.3 Geology and Field Observations The following section discusses the subjective field observations and geology documented Iduring this investigation based on the interpretations of the field geologist • The geology of the site is predominately clays and sandy clays with lesser amounts of silts and sands • For most of the boreholes, except for those drilled very close to the old tank pit, gasoline odor was not observed in the sod samples until a depth of 20 feet bgs It appears that the I gasoline spread out on top of the old groundwater table • The deeper soil encountered in SB-109 was a blue/grey to blue/green color so it was difficult to visually determine when drilling had progressed past the contamination 4.0 CONCLUSIONS AND RECOMMENDATIONS Based on our interpretation of the data collected over the course of this subsurface investigation we have reached several conclusions These conclusions are based on the premise that the data we considered, although incomplete, are representative of actual site conditions We acknowledge that there may be undiscovered conditions, which would upon their consideration, change our interpretation and thus our conclusions I