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17 <br /> ti <br /> presented in Appendix A The site drinking water well was sampled <br /> through a sampling port and was purged prior to sampling <br /> Well sampling purge water was disposed of through the on-site activated <br /> carbon treatment system <br /> 4 . 0 GROUNDWATER SAMPLE ANALYSIS <br /> The groundwater samples were analyzed for total petroleum <br /> hydrocarbons as diesel (TPH-D) by EPA Method 351018015, and total <br /> petroleum hydrocarbons as gasoline (TPH-G), benzene, toluene, ethyl <br /> benzene and total xylenes (collectively known as BTEX), fuel oxygenates, <br /> lead scavengers, and 1,2-dichloropropane by EPA Method 8260 The <br /> analytical results for this and previous sampling periods are presented in <br /> Tables Two and Three The certified analytical report and chain-of- <br /> custody documentation are included as Appendix B <br /> 5.0 CONCLUSIONS <br /> The analytical results this quarter show a general decrease in hydrocarbon <br /> concentrations from previous results For the first time since the May <br /> 1999 measurement, no free-floating hydrocarbons were present on the <br /> groundwater surface in monitoring well MW-5 <br /> Isoconcentration maps for TPH-G, benzene, and MTBE in the shallow <br /> water-bearing zone are presented as Figures 5 through 7, respectively <br /> 1,2-dichloropropane was detected in groundwater samples collected from <br /> monitoring wells MW-7, MW-8, MW-17, MW-18, and the on-site drinking <br /> water well None of the 1,2-DCP concentrations exceeded DHS MCLs for <br /> drinking water No 1,2-dichloroethane (1,2-DCA) was detected in any of <br /> the site monitoring wells this quarter <br /> Ethanol and methanol were detected in groundwater samples collected <br /> from several site wells, including several off-site domestic wells In most <br /> of these cases, neither ethanol nor methanol was detected in these <br /> samples previously Since methanol is a common laboratory contaminant <br /> and may be used to factory clean VOA vials, several of the off-site <br /> domestic wells were resampled to confirm the presence of methonal <br /> During the resampling, the VOA vials were rinsed with the well water to be <br /> sampled several times prior to collecting and sealing the vials In each <br /> case, no methanol was detected in the confirmation sample For this <br /> Frank's One Stop Quarterly Report — March 2001 Sampling <br /> -3- <br />