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Analytical Results
<br /> Data from the November 2000 sampling event indicate that the groundwater beneath the
<br /> Disco site contains detectable levels of total petroleum hydrocarbons (T PH)as gasoline,
<br /> BTEX compounds (benzene,toluene,ethyl benzene and total xylenes), 1,2-Dichloroethane
<br /> (1,2-DCA), and 1,2-Dibromoethane,also known as ethylene dibromide (EDB). Analytical
<br /> results are presented in Tables 4,5,and 6. Table 4 presents groundwater sample analysis for
<br /> TPH-gasoline and benzene,toluene,ethyl benzene,and xylenes (BTEX). Table 5 presents
<br /> analytical results for MTBE and other oxygenate compounds. Table 6 presents analytical
<br /> results for 1,2-DCA and EDB. The results are summarized below,dependent upon the
<br /> location of the well.in relation to the plume: upgradient,crass-gradient,or within the
<br /> plume.
<br /> Upgradient Wells-MW-DIS,5,-6,-7S, -71D,-8S,and-81).
<br /> All upgradient wells were sampled and analyzed for oxygenates, 1,2-DCA and EDB during
<br /> this sampling event. There were no detections of these compounds in these wells.
<br /> Cross-gradient Wells-MW-DIS-3,-9,and-10.
<br /> All crossgradient wells were sampled and analyzed for oxygenates, 1,2-DCA,and EDB
<br /> during this sampling event. There were no detections of these compounds in these wells.
<br /> Wells Within the Plume-MW-DIS-1, MW-DIS-2, NP-1-70', NP-1-80', NP-1-90', SVE-South and
<br /> SVE-North
<br /> TPH as gasoline and BTEX compounds were detected in groundwater samples collected
<br /> from monitoring wells MW-DIS-2,NP-1-70',NP-1-80',NP-1-90',SVE-South and SVE-North.
<br /> The concentrations detected in these wells are consistent with previous sampling events (see
<br /> Table 4).Concentrations continue to decline in MW-DIS-2. Groundwater samples were
<br /> collected from MW-DIS-1 and submitted to the lab,however,due to a lab error,the samples
<br /> were not analyzed.
<br /> Oxygenates
<br /> Methyl-tert-Butyl Ether(MTBE), Cert-Butanol(TBA),Di-isopropyl ether(DIPE),Ethyl-tert
<br /> butyl ether(ETRE),and tert-Amyl Methyl ether(TAME) were not detected in any of the
<br /> wells during this monitoring event.All oxygenates were analyzed by EPA Method 8260B
<br /> during this sampling event.
<br /> There have been no confirmed detections of the MTBE,DIPE, ETBE,and TAME at this site.
<br /> TBA has been detected once,in five different wells,and twice in MW-DIS-1.
<br /> Other Additives
<br /> All monitoring wells were sampled and analyzed for oxygenates, 1,2-DCA and EDB during
<br /> this sampling event. These compounds are known as lead scavengers and were a common
<br /> gasoline additive.
<br /> EDB was detected in MW-DIS-1,NP-1-90',NP=1-80',NP-1-70',SVE-North,and SVE-South
<br /> at concentrations of 36, 150,960, 89, 1.6, and 360 gg/L,respectively. EDB was not detected in
<br /> SVE-North during the previous sampling event. 1,2-DCA was detected in MW-DIS-1,
<br /> NP-1-90',NP-1-80',NP-1-70',SVE-North,and SVE-South at concentrations of 150,260, 1,600,
<br /> 2
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