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' 5.0 SPECIFIC INFORMATION FOR CLOSURE REQUEST <br /> ' <br /> 551 Introduction <br /> This section provides information specifically required for closure review as per the October 7, <br /> 1993 Addendum to Appendix A of the Tn-Regional Recommendations <br /> 1 <br /> 5.2 Rationale for Closure <br /> Based on the results of the confirmation boring sampling, it appears that TPHg, benzene, <br /> toluene, and TPHd have been remediated to concentrations below method detection limits <br /> Residual concentrations of ethyl benzene and total xylenes at low concentrations of 0 010 ppm <br /> and 0 16 ppm were detected in the soil at a depth of 21 5 feet bgs, well above the groundwater <br /> elevation on-site Historical groundwater data indicates that the highest groundwater elevation <br /> on-site was 59 feet bgs In addition, groundwater sampling results indicate that TPHg, TPHd <br /> and BTEX have not been detected in four quarters of monitoring and sampling The <br /> ' remediation of the soil on-site by vapor extraction appears to have prevented degradation of <br /> the groundwater on-site <br /> 5.3 Site Specific Information Summary <br /> o Thirty g supply groundwater su 1 wells are known to exist within 2000 feet of the site, based <br /> upon information provided by the Department of Water Resource Locations of the <br /> wells are shown on Figure 7 <br /> o Depicted on enclosed figures are the site location and nearby surface waters (Figure 1), <br /> the site to scale and former tank locations (Figure 2), well and boring locations <br /> ' (Figures 2 and 3), most recent groundwater gradient contours (Figure 6), the former <br /> area of impact in soil (Figure 4), and the site plan of the remediation system (Figure <br /> ' S) <br /> ' o Water level data are presented in Table 3 During the investigative history of the site <br /> depth to groundwater has ranged from 59 60 to 74 46 feet below grade <br /> n 10540061reports\CLO1195 doc 12 <br /> 1 <br /> SMTH <br />