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