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1 <br /> concentrations ranging from 14,000 ppm to 61,000 ppm, with associated aromatic <br /> hydrocarbons, benzene, toluene, ethyl benzene and total xylenes (BTEX) present. <br /> Results of an investigation conducted by Weston in October 1988 indicated no detectable <br /> diesel fuel components in soil or groundwater samples collected during installation and <br /> sampling of three monitoring wells These wells - MW-1, MW-2, and MW-3 - are located <br /> ' approximately 100 feet northwest, and 75 feet east and 100 feet south, respectively, of the <br /> former tank locations (Figure 2). The monitoring wells were installed to a depth of <br /> approximately 65 feet. <br /> ' In October 1992, Remediation Services, Inc. (RSI) representatives drilled and sampled two <br /> soil borings one boring in the former tank excavation (B-1), and one boring approximately <br /> ten feet north of the excavation (the latter was completed as groundwater monitoring well <br /> ' MW-4). The results of the soil samples analyzed indicate that petroleum hydrocarbons were <br /> detected to a depth of 70 feet in the soil boring B-1 (13 ppm TPH as diesel) and to a depth of <br /> 60 feet in the soil boring MW-4 (2100 ppm TPH as diesel) None of the chlorinated organic <br /> compounds previously detected during the tank excavation sampling were detected in either <br /> boring. <br /> Additional soil investigation conducted by RSI in February of 1993 included sampling and <br /> characterization of four soil borings (B-101 through B-104) drilled to depths of 74 feet below <br /> the ground surface (Figure 2). TPH as diesel was detected at a maximum concentration of 11 <br /> ppm at a depth of 55 feet in boring B-103. In December of 1993, RSI installed two <br /> additional groundwater monitoring wells (MW-5 and MW-6) Monitoring wells MW-5 and <br /> MW-6 are screened between 70 and 90 feet below the ground surface, and together with <br /> MW-4 are currently being monitored and sampled on a quarterly basis for TPH as diesel and <br />' BTEX by BSK and Associates. <br /> 1.3 Scope of Work <br /> The scope of work completed during flus field effort included excavation and disposal of <br /> petroleum impacted soil, and installation of a vapor observation point within the excavation <br /> rconcurrent with backfill operations. These activities were implemented as a source reduction <br /> measure, in an effort to mitigate the potential for migration of the residual petroleum <br />' hydrocarbons in the soil to the underlying groundwater. <br /> MZ M&23/95NDBF/95-0007 2 <br />