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i e Irl Groundwater samples,collected from MW-I through MW-4,were also analyzed for TPHg and aromatic hydrocarbons. Results of analyses from groundwater samples are summarized w on Table 2,Appendix A. In May and June 1990, WGR conducted a second subsurface investigation. Three soil F" borings,B-5 through B-7 were drilled and completed as groundwater monitor wells, MW-5 a through MW-7(Figure 3). Twelve soil samples were collected from the three borings and analyzed for TPHg and aromatics. Table IB,Appendix A,summarizes the results of the soil sample analyses; Fable 2, Appendix A summarizes the results of the groundwater sample analyses collected from MW-5 through MW-7. In June 1991, WGR attempted to perform groundwater monitoring of wells MW-1 through i 4 MW-7. All seven wells were dry, however, indicating that the groundwater table had receded to below a depth of 70 feet. l.3 3.0 Y N DRE EN MON In August 1991,Remedia;=on Services,Inc.(RS)was engaged by AP to design a remediation t . system for treating TPHg contaminated soil at the site. The following discussion presents RS's conclusions and recommendations for remedial actions for site cleanup. i The analytical results, i.e. elevated concentrations of TPHg in soil Boring B-1 (up to 5200 PPM) and non-detectable TPH9 concentrations in Borings B-2, B-3, and B4, indicate that soil beneath the former tank emplacement has been impacted by petroleum hydrocarbon . 4 contamination. Based on our experience with similar projects, it is likelythat the contamination is localized within a relatively vertical column of soil. Groundwater beneath the former tank emplacement has also been impacted by TPH9 f , contamination (refer to Table 2, Appendix A). Elevated concentrations of TPHg and aromatics were detected in groundwater sampled from MW-1, MW-3, MW-5 and MW-7, ' WGR reported that the estimated groundwater flow direction at the time of sampling,June 1990,was towards the south to south-southwest. Wells MW-3,MW-5 and MW_7 are located west,southwest, and south, respectively, of MW-1 and the xormer tank emplacement. The analytical data combined with the;groundwater directional flow data indicate that the source G of the groundwater contamination is from the contaminated soil. bar Detectable concentrations of 1,2-DCA and EDB were also reported in the groundwater samples. These chemicals are common gasoline fuel additives and are typically also present in TPHg contaminated groundwater. In one groundwater sample collected from MW-2, PCE was detected at a concentration of 3.5 ppb. The source of PCE contamination in this sample is unknown,but at this low concentration,it could possibly be due to vapor intrusion to the laboratory or during sample handling, 2 bo REMEDIATION SERVICES, INC,