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29 January 1998 <br /> AGE-NC Project No 95-0184 <br />' Page 3 of 4 <br />' 3 2 ANALYTICAL RESULTS OF GROUND WATER SAMPLES <br /> TPH-g was detected in each well sampled,with concentrations as high as 170,000 /,Zg/1 (micrograms <br /> per liter, Equivalent to parts per billion, ppb) Benzene was detected at concentrations as high as <br /> 40,000 ppb TPH-d was detected in the sample from MW-4 at a concentration of 11,000 ppb Di- <br /> isopropyl ether (DIPS) and tertiary butanol were detected in the sample from MW-3 at <br /> concentrations of 20 ppb and 13 ppb, respectively MTBE was detected in samples collected from <br /> VW-2B, VW-3 and VW-4 at concentrations of 2,100 ppb, 1,800 ppb and 1,100 ppb, respectively <br /> 1,2-Dichloroethane (DCA) was detected in the samples from MWA, MW-3, MW-4, MW-7, and <br /> VW-3 at a concentrations as high as 2,000 ppb Six additional constituents were detected with EPA <br /> Method 8260 at concentrations as high as 3,000 ppb Analytical results are summarized on Tables <br />' 2 and 3' The laboratory report (MAI sample Nos 82317-82326) and chain-of-custody forms are <br /> included in Appendix B <br /> Hydrocarbon concentrations detected in samples collected from MW-4,VW-5B,VW-3,VW-4,VW- <br /> 513 and VW-5C are indicative of the presence of free product Lower hydrocarbon concentrations <br /> were detected in MW-7, located between MW-4 and the remaining wells The lower hydrocarbon <br /> concentrations detected in samples collected from MW-1, MW-2 and MW-3 are likely due to <br /> drowning of these wells <br /> 4.0, DISCUSSION AND CONCLUSIONS <br /> IBased upon data collected from the site, AGE concludes the following <br /> • Petroleum hydrocarbons were detected in each well sampled, at concentrations as high as <br /> 170,000 ppb The lateral extent of hydrocarbons in ground water has not been determined <br /> Additional monitoring wells will be necessary to delineate the horizontal extent of <br /> hydrocarbon-impacted ground water <br /> • Ground water flow direction was determined to be east-northeasterly in July 1997, and to be <br /> east-southeasterly in October 1997 at,the site <br /> • Due to the rise of ground water elevation at the site, ground water is currently approximately <br /> fifteen feet above the screened interval in monitoring wells MW-1 through MW-3, five feet <br /> above the screened interval in MW-4 and at the top of the screened interval in MW-7 These <br /> wells recharge rapidly, possibly preventing significant drawdown in wells MW-1 through <br /> MW-3 during purging The hydrocarbon concentrations detected in these `drowned' wells <br /> may not be representative of shallower ground water where the maximum hydrocarbon <br /> impact would be expected <br /> Advanced GeoEm tronmcmai,Inc <br /> I i <br />