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n 1.2 2 Preliminary Investigation_and Evaluation On March 26, 1996, IT Corporation published Site Investigation Report, which documented the results of soil and groundwater-grab sampling from two on-site Geoprobe sod borings (SB-3 and SB-4) Two additional soil borings (SB-1 and SB-2) were terminated at the buried concrete slab beneath the former USTs The boring locations are shown on Figure 2 Soil and groundwater beneath the former USTs were impacted by petroleum hydrocarbons The soil sample analytical results are summarized in Table 3, and the groundwater analytical results are summarized in Table 4 1 2 3 Monitoring Well Installations On January 9, 2003, Ramage Environmental published Monitoring Well Installation Report, which documented the installation, survey, and initial sampling of three groundwater table monitoring wells (MW-1, MW-2 and MW-3) The well locations are shown on Figure 2 Soils to the total drilling depth of 65 feet mostly consisted of massive clay and silt soils, and relatively thin and discontinuous sand intervals less than five feet thick During drilling, saturated sod was first observed at approximately 56 to 57 feet below ground surface (bgs), and the static depth to the groundwater table, ranged from 46 28 to 46 72 feet bgs As such, groundwater appeared to be present under semi-confined conditions The groundwater potentiometnc surface appeared as a regular plane dipping to the north i In soil, 3 of the 15 samples analyzed contained detectable concentrations of petroleum hydrocarbons The highest concentrations were observed between 45 and 55 feet within the capillary fringe and zone of groundwater fluctuation Laterally, the extent of impacted soil appeared to be limited to beneath the former fuel farm Vertically, the extent of impacted sod appeared to be defined The sod sample analytical results are summarized in Table 3 The9 roundwater samples collected from all three monitoring wells contained detectable concentrations of petroleum hydrocarbons The highest concentrations were detected at MW-1 840 micrograms per liter (µg11) of Total Petroleum Hydrocarbons (TPH)-as-tet fuel, 7,700 4g11 of TPH-as-gasoline, 1,300 µg/l of benzene, 460 µgll of toluene, 490 µg11 of ethylbenzene, and 670 µgh of xylenes The lateral extent of impacted groundwater was not defined The groundwater analytical results are summarized in Table 4 5