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II '�al
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<br /> Mr Jeff Wong
<br /> Page 3 of 4
<br /> • 3.0 GROUNDWATER ANALYTICAL RESULTS
<br /> Argon Laboratories analyzed the groundwater samples for total petroleum hydrocarbons as
<br /> gasoline (TPHg) using EPA 8015M, benzene, toluene, ethylbenzene, and total xylenes (BTEX)
<br /> using EPA 8020, and oxygenated gasoline additives, ethylene dibromide (EDB) and 1,2-
<br /> dichloroethane (1,2-DCA) using EPA 8260B Well MW I was not sampled due to the presence of
<br /> free product
<br /> Wells MW2, MW3, and MW4 contained TPHg at concentrations of 1,500 parts per billion (ppb),
<br /> 820 ppb, and 1,000 ppb, respectively No TPHg was detected in wells MW5, MW6, MW7,
<br /> MW8, or MW9B
<br /> Benzene was detected in wells MW2, MW3 and MW4 at concentrations of 40 ppb, 4 4 ppb and 13
<br /> ppb, respectively No benzene was detected in wells MW5, MW6, MW7, MW8, or MW913
<br /> MTBE was detected in wells MW2, MW3, MW4, and MW6 at concentrations of 230 ppb, 12,000
<br /> ppb, 21,000 ppb, and 940 ppb, respectively No MTBE was detected in wells MW5, MW7,
<br /> MWS, or MW913
<br /> Toluene, ethylbenzene, and xylenes were detected only in well MW2 at low to moderate levels
<br /> Table 3 presents a summary of groundwater analytical results
<br /> Attachment D contains a copy of the laboratory report and chain-of-custody documentation
<br /> Figures 3 and 4 present isoconcentration maps of benzene and MTBE, respectively, in shallow
<br /> groundwater beneath the site Attachment E contains plots showing the concentrations of
<br /> TPHg, benzene, and MTBE over time in all site wells
<br /> 4.0 SUMMARY AND CONCLUSIONS
<br /> Free product thickness in well MW1 ranged from 1 61 to 0 01 feet between October 1, 2002
<br /> and December 30, 2002 Approximately 29 gallons of product/water mixture was removed
<br /> from well MW 1 during the same period A total of approximately 113 gallons of
<br /> product/water mixture has been removed from this well since August 16, 2001 Figure 5
<br /> presents a chart showing the measured depths to water and product over time in well MW1
<br /> Groundwater levels rose an average of 0 73 feet in the shallow aquifer between September
<br /> 2002 and December 2002 Groundwater flow remained relatively consistent at a gradient of
<br /> approximately 16 feet per mile, although an apparent groundwater depression was present near
<br /> well MW3 when groundwater elevations were last measured on December 11, 2002
<br /> The lateral extent of TPHg and BTEX has been defined in shallow groundwater beneath the
<br /> site except to south and west of well MW2 The lateral extent of MTBE has not been
<br /> completely defined in shallow groundwater beneath the site
<br /> G 1Data1GROUNDZEITULEBURGV2eports\QMRWQM2002 doc
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