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. Project No 58100-06-11A March 15, 1995 Page 2 120 ppm and maximum total petroleum hydrocarbons as gasoline and diesel (TPHg and TPHd) concentrations of 2,000 and 58 ppm, respectively The TPHg concentration of 2,000 ppm was reported for a soil sample obtained at a depth of 14 feet below the existing ground surface (bgs) from the fill riser end (west end) of the gasoline UST In March 1992, Alton Geosciences advanced two soil borings (SB-1 and SB-2) to a depth of 66 5 feet bgs, constructed three monitoring wells (MW-1 through MW-3) to a depth of 79 5 feet bgs, and collected soil and groundwater samples for chemical analyses The approximate locations of the borings and wells are depicted on Figure 2 The results of the analyses indicated that TPHg existed in soil in SB-1 and MW-3 at a depth of 46 feet bgs at concentrations of 120 and 30 ppm, respectively TPHd was also reported at the 46 foot depth in SB-1 and MW-3 at concentrations of 3 8 and 31 ppm, respectively The laboratory reports indicate that the TPHd results "do not appear to contain diesel " TPHg and TPHd were not detected in SB-2, and MW-1 and MW-2 with the exception of 1 0 ppm TPHg reported at 46 feet bgs in MW-2 Groundwater sampled from MW-1 through MW-3 in April 1992 was reported to be impacted with TPHg at concentrations between 2,400 and 4,900 ppb, TPHd between 73 and 180 ppb, and benzene between 260 and 1,100 ppb Groundwater was encountered at a depth of approximately 66 feet bgs and the gradient was reported to be 002 ft/ft to the west In October 1993, Environmental Assessors obtained groundwater samples from MW-1 through MW-3 for TPHg and BTEX analyses TPHg was reported at concentrations between 2,700 and 4,700 ppb, and benzene between 520 and 11,000 ppb Groundwater was encountered at a depth of approximately 68 feet bgs and the gradient was determined to be 0006 ft/ft to the northeast Geocon sampled MW-1 through MW-3 on March 6, 1995 The results of laboratory tests indicated TPH as gasoline concentrations in each well ranging between 1,400 and 2,200 ug/l Benzene was detected at a concentration of 150 ug/l for each of the three wells, toluene was detected at concentrations ranging from 10 to 75 ug/1, ethylbenzene was detected at concentrations ranging from 4 1 to 13 ug/l and total xylenes were detected at concentrations ranging from 15 to 71 ug/l in each of the three wells TPH as diesel was not detected above the laboratory equipment detection limit of 500 ug/l for each of the three wells Groundwater was encountered at a depth of approximately 65 feet bgs The groundwater gradient was determined to be 0007 ft/ft to the north A cumulative summary of the groundwater monitoring data for the site is presented on the . attached Table I