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Mr. Kyle Christie Project 20805-146.006 <br /> August 5, 1996 <br /> Page 3 <br /> Total oil and grease, halogenated volatile organic compounds (HVOCs), and <br /> polychlorinated biphenyls were not detected in the samples analyzed; however, total <br /> extractable hydrocarbons were detected. During drilling on April 28, 1992, approximately <br /> 5 gallons of gasoline were released from a fractured product line between the dispenser <br /> islands and the underground tank cavity. Results of the initial assessment of the release <br /> were reported in RESNA's "Second Quarter 1992 Status Report and Addendum <br /> Workplan" (RESNA, August 11, 1992, Report No. 31009-6). <br /> Dissolved gasoline hydrocarbons were detected in water samples collected from the three <br /> wells. Purgeable halocarbons were not detected, except for 1,2-dichloroethane, which was <br /> detected in monitoring well MW-2. Fecal and total coliform bacteria were not detected in <br /> the sample collected from well MW-3. <br /> In January 1993, RESNA observed the drilling of seven soil borings (B-13 through B-19) <br /> and the installation of two groundwater monitoring wells (MW-4 and MW-5) and four <br /> vapor extraction wells (VW-4 through VW-7). Results of this assessment were reported in <br /> RESNA's "First Quarter 1993 Status Report" (RESNA, June 9, 1993, Report <br /> No. 31009-7). The report indicated that hydrocarbons present in soil below 25 feet and in <br /> groundwater were probably from an off-site source. Therefore, ARCO requested that an <br /> investigation of soil and groundwater be performed off site and upgradient of the ARCO <br /> station to determine whether hydrocarbons were present upgradient of the site. <br /> In October 1993, RESNA observed the drilling of two soil borings (B-20 and B-21) and <br /> the installation of two groundwater monitoring wells (MW-6 and MW-7). Analytical data <br /> indicated that residual hydrocarbons were present in the borings (RESNA, February 15, <br /> 1994, Report No. 31009-9). Total petroleum hydrocarbons as gasoline (TPHG) and <br /> benzene concentrations ranged from below laboratory detection limits to 1,200 parts per <br /> trillion (ppm) and from below laboratory detection limits to 1.2 ppm, respectively. The <br /> highest concentration was detected at 20 feet below ground surface (bgs). Dissolved <br /> gasoline hydrocarbons were detected in the monitoring wells. In addition, HVOCs were <br /> also detected in groundwater samples collected from monitoring wells MW-6 and MW-7. <br /> In May 1995, EMCON prepared an off-site evaluation report (EMCON, "Evaluation of <br /> Off-Site Sources," May 5, 1995). EMCON identified the following four potential <br /> upgradient/off-site sources: (1) Texaco Service Station located at 440 West Charter Way, <br /> (2) Chevron Service Station located at 508 West Charter Way, (3) Transmission Store <br /> located at 515 West Charter Way, and (4) Shell Service Station located at 620 West <br /> Charter Way. Residual hydrocarbons have been detected at the Texaco and Shell service <br /> stations and adjacent to the Transmission Store. High concentrations of residual <br /> SAL'\N:\PJM805\08051460.6DS-95\c}b:3 <br />