ARCHIVED REPORTS XR0000033 - Laserfiche WebLink

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�i 1 2 2 Prelimmary Investigation and Evaluation On March 26, 1996, IT Corporation published Site Investigation Report, which documented the �l results of soil and groundwater-grab sampling from two on-site Geoprobe soil 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 northwest side of 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 1 2 3 Monitoring WellInstallations 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 1 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 soil 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 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 soil appeared to be defined The soil sample analytical results are summarized in Table 3 The groundwater 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-het fuel, 7,700 pg/I of TPH-as-gasoline, 1,300 µg11 of benzene, 460 µg11 of toluene, 490 gg/I of ethylbenzene, and 670 µg11 of xylenes The lateral extent of impacted groundwater was not defined The groundwater analytical results are summarized in Table 4 . 4