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Ms. Marla Guensler <br /> July 8, 1992 <br /> Page 4 <br /> TABLE 2 - Continued <br /> Ground Water Sample Analytical Results <br /> Concentrations in Parts per Billson(ppb) <br /> Monitoring Ethyl- <br /> Well Date Benzene Toluene benzene Xylenes MHU! <br /> MW-6 02/11/92 06 <05 <05 <05 51d <br /> 03/18/92 06 <05 <05 <05 <50f <br /> 06/04/92 <05 <05 <05 <05 <50 <br /> a Total Petroleum Hydrocarbons as gasoline <br /> b Atypical chromatogram Three unknown peaks were observed Chlorinated hydrocarbons are suspected <br /> Atypical chromatogram Analysis of this sample by EPA Method 624 on April 17, 1992, (past EPA <br /> recommended holding time) was positive for the following chlorinated hydrocarbons vmylchlonde, <br /> cis-1,2-dichlorethene, trichloroethene and tetrachlorethene These peaks resulted in a positive fuel <br /> hydrocarbon result <br /> d Atypical chromatogram Four unknown peaks were observed causing a positive fuel hydrocarbon result <br /> Chlorinated hydrocarbons are suspected. <br /> e Atypical chromatogram An unknown peak was observed between MTBE and benzene Chlorinated <br /> hydrocarbons are suspected <br /> f Atypical chromatogram Analysis of this sample by EPA Method 624 on April 17, 1992, (past EPA <br /> recommended holding time)was positive for the following chlorinated hydrocarbons chlorobenzene and <br /> 1,2-dichlorobenzene <br /> The concentrations of BTEX and TPH as gasoline in the ground water sample collected from <br /> monitoring wells MW-2 and MW-6 on June 4, 1992, were reported below the laboratory detection <br /> limits The ground water sample collected from monitoring wells MW-I and MW-5 were reported <br /> below the laboratory detection limits for toluene, ethylbenzene, and xylenes and TPH as gasoline, <br /> and 1.1 and 1 0 ppb benzene, respectively The ground water sample collected from monitoring <br /> wells MW-3 and MW-4 were reported below the laboratory detection limit for toluene, ethylbenzene <br /> and xylenes, 25 and 0 6 ppb for benzene and 87 and 67 ppb TPH as gasoline, respectively. The <br /> inferred distribution of dissolved benzene and TPH as gasoline in ground water beneath the site is <br /> illustrated in Figures 4 and 5 <br /> The halogenated organics scan (EPA Method 624) detected the presence of 1,2-Dichlorobenzene at <br /> a concentration of 15 ppb in monitoring well MW-5 and 5 5 ppb in monitoring well MW-6 <br /> Chlorobenzene was also detected in the ground water in monitoring well MW-5 at a concentration <br /> of 5 8 ppb Concentrations of cis-1,2-Dichloroethene were detected in the ground water samples <br /> collected from monitoring wells MW-1, MW-4 and MW-5 The highest concentration of <br /> cis-1,2-Dichloroethene was detected in the off-site monitoring well MW-4 at a concentration of <br /> 130 ppb Trichloroethene and Tetrachloroethene were also detected in the ground water in <br /> monitoring well MW-4 at concentrations of 16 ppb and 29 ppb, respectively Table 3 summarizes <br /> the halogenated organics analytical results of the ground water samples collected on June 4, 1992 <br />