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. Site No: 11192 A site plan (Figure A-1) and tabulated data from EMCON's supplemental assessment work (Table A-1) are included with this report as Attachment A. Photographs from EMCON's site visit are included as Attachment B. Copies of figures and tabulated data from previous investigations are included as Attachment C. Copies of boring logs and laboratory reports from EMCON's supplemental site assessment work are included as Attachment D. 2. Previous Investigations and Remedial Activities Target conducted a soil gas survey at the site in March 1989 (Target, 1989). Twenty- four soil gas samples were collected and submitted for analysis of MTBE/pentane and BTEX (Figure C-1). ]�ME/pentane (up to 19,760 µg/L) and BTEX (up to 2,051 Mcg/L benzene, 1,932 ,ug/L toluene, 946 µglL ethylbenzene, 216 ,ug/L m- and p-xylene, and 52 µg/L o-xylene) were detected in samples collected on site (Table C-1). The highest concentrations of total volatiles (19,660 and 97,110 14g/L) were detected in samples collected to the east of the gasoline UST complex and to the east of the southern pump island (Figure C-1). . A sensitive receptors survey was contained in BP files (EMCON, 1959). The report, dated April 13, 1989, indicated that a public water supply well was located within 1,100 feet of the site, and a private water supply well was located within 90G feet of the site. The report also stated that the aquifer classification was not available. IT conducted a site assessment of the site in June 1990 (IT, 1990). The assessment included the installation and sampling of four 30-foot monitoring wells (MW-1 through MW-4; Figure C-2). Soil encountered during drilling consisted primarily of lean clay below 2 to 3 feet of gravel fill. A clayey sand layer was encountered at approximately 22 to 26 feet bgs. Groundwater, reported to flow north-northeast at the time of the site assessment, was encountered at approximately 22 feet bgs. IT collected soil samples at 5-foot intervals. The samples with the highest PID readings were analyzed for TPH-G and BTEX (IT, 1990). A sample from boring MW-4, adjacent to the waste oil and motor oil UST complex, was also analyzed for TPH-D, TOG, and HVOCs. Benzene at 0.82 ppm and ethylbenzene at 0.043 ppm were detected in the 20-foot bgs sample collected from boring MW-3, located north of the gasoline UST complex (Table C-2). No other compounds were detected in the samples analyzed. Groundwater samples collected from each monitoring well were analyzed for TPH-G and BTEX. Samples from MW-4 were also analyzed for TPH-D, TOG, HVOCs, and metals. No free-floating product was observed in any of the monitoring wells. TPH-G (up to 200 ppb) was detected in samples collected from wells MW-1 and MW-3 BrroS/RPT/11192RPT.d07-941LAM116:5 Rev.0. 12/27/94 0952-090.03 2