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a <br /> A S S O C I A T E S I N C <br /> MTBE was detected in the sample from well MW-1 at concentration of 37 0 ppb, however this <br /> detection was not confirmed by laboratory EPA method 8260 In November 1997 groundwater <br /> samples from wells MW-1 through MW-5 were analyzed for fuel oxygenates utilizing EPA <br /> method 8260 and none were detected but groundwater was above the top of screen in these wells <br /> during that event MTBE was not detected in any of the other groundwater wells <br /> Vapor Wells <br /> Results of laboratory analyses indicated dissolved TPHg, TPHd, and BTEX constituents were <br /> detected 1n the samples from vapor wells VW-4, VW-5s, and VW-5d Concentrations reported in <br /> well VW-4 were relatively low and have generally remained the same since the well was last <br /> sampled in November 1997, although benzene did increase to 9 5 ppb and now exceeds the MCL <br /> Concentrations 1n wells VW-5s and VW-5d are elevated but have decreased up to three orders of <br /> magnitude since last sampled 1n November 1997 Benzene exceeds the MCL 1n both wells The <br /> groundwater sample from vapor well VW-5d also contained MTBE at 210 ppb Groundwater <br /> samples from vapor wells VW-2d, VW-4, and VW-5d did contain detectable concentrations of <br /> MTBE 1n November 1997 and these results were confirmed by EPA Method 8260 Results of <br /> laboratory analyses are summarized in Table 2 <br /> SUMMARY <br /> • The groundwater flow direction and gradient were consistent with those evaluated during <br /> previous events Dissolved gasoline hydrocarbons were detected in the sample from groundwater <br /> wells MW-1 and RW-1 and vapor wells VW-4, VW-5s, and VW-5d Dissolved hydrocarbons in <br /> the diesel range were detected in the samples from groundwater wells MW-1, MW-3, MW-5 and <br /> RW-1 and vapor wells VW-4, VW-5s, and VW-5d during the reporting period BTEX <br /> constituents were detected 1n wells MW-1, VW-4, VW-5s, and VW-5d Benzene exceeds the <br /> MCL 1n these four wells MTBE was detected 1n the samples from groundwater well MW-1 and <br /> vapor well VW-5d Concentrations have generally remained the same in the groundwater wells <br /> and decreased in the vapor wells since they were last sampled <br /> W 162574162574 0119436"QSR99doc 3 <br />