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<br /> . A S S O c I A T E S I M C
<br /> QUARTERLY GROUNDWATER MONITORING ACTIVITIES
<br /> On December 5, 2002, ATC Associates personnel collected groundwater samples from
<br /> monitoring wells MWI through MW10 and CW The locations of the monitoring wells are
<br /> shown on Figure 2 Prior to collection of groundwater samples, the depth to water, pH, electrical
<br /> conductivity, and temperature were measured in the monitoring wells and recorded A minimum
<br /> of three well casing volumes was purged from each well prior to sampling The wells were
<br /> allowed to recover and samples were collected from each well using dedicated disposable bailers
<br /> After groundwater samples were collected, dissolved oxygen concentrations were measured in
<br /> each well Groundwater well purge and sample logs are contained in Attachment 1
<br /> The groundwater samples collected from each well were submitted to State-certified Argon
<br /> Laboratories, Inc (ELAP Cert No 2359) for chemical analysis of TPHg, benzene, toluene,
<br /> ethylbenzene, xylenes (BTEX) utilizing EPA methods 8015/8020, and methyl tertiary butyl ether
<br /> (MTBE), ethyl tertiary butyl ether (ETBE), tertiary butyl alcohol (TBA), tertiary amyl ether
<br /> (TAME), di-isopropyl ether (DIPE), 1,2-dzchloroethane (1,2-DCA), and ethyl dibromide (EDB)
<br /> utilizing EPA method 8260
<br /> Groundwater Analytical Results
<br /> . TPHg and/or BTEX were detected above laboratory method detection limits in the samples
<br /> collected from wells MWI, MW2, MW3, MW5, MW6, and MW7 The groundwater samples
<br /> collected from wells MW2, MW4, MW5, MW10, and CW contained low concentrations of
<br /> MTBE ranging from 2 8 parts per billion (ppb) to 5 6 ppb The groundwater samples collected
<br /> from wells MWI, MW3, MW6, MW7, MWS, and MW9 did not contain detectable
<br /> concentrations of MTBE, but the detection limits in the sample in wells MWI, MW3, and MW7
<br /> were elevated due to dilutions factors None of the groundwater samples collected contained
<br /> detectable concentrations of ETBE, TBA, TAME, DIPS, 1,2-DCA, or EDB The sample
<br /> collected from well CW contained no detectable concentrations of petroleum hydrocarbons other
<br /> than a low concentration of MTBE Groundwater samples from wells MWI, MW3, and MW7
<br /> continue to contain the highest concentrations of TPHg and BTEX A summary of analytical
<br /> results is presented in Table 1 Groundwater laboratory data sheets and chain-of-custody
<br /> documentation are contained in Attachment 2
<br /> Groundwater Flow Direction
<br /> Water level measurements were collected from wells MWI through MW10, and CW on
<br /> December 5, 2002 Water levels ranged from 24 15 to 28 18 feet below the tops of the well
<br /> casing elevations, representing an average decrease in the water table elevation of approximately
<br /> 0 62 feet since October 2002 The water level data were used to develop the groundwater
<br /> elevation contour map (Figure 3) Assuming that horizontal isotropic conditions prevail,
<br /> . groundwater in the uppermost aquifer beneath the site flowed towards the northeast The average
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