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<br /> A S S O C I A T E S I N c
<br /> SAMPLING ACTIVITIES
<br /> On September 23, 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 (DIPS), 1,2-dichloroethane (1,2-13CA), and ethyl dibrom>de (EDB)
<br /> utilizing EPA method 8260
<br /> ANALYTICAL RESULTS
<br /> TPHg and/or BTEX were detected above laboratory method detection limits in the samples
<br /> collected from wells MW1, MW3, MW5, MW6, and MW7 The groundwater samples collected
<br /> from wells MW2, MW4, MW5, MW6, MW10, and CW contained low concentrations of MTBE
<br /> ranging from 3 5 parts per billion (ppb) to 6 1 ppb The groundwater samples collected from
<br /> wells MWI, MW3, MW7, MW8, and MW9 did not contain detectable concentrations of MTBE,
<br /> but the detection limps in the sample in wells MWI, MW3, and MW7 were elevated due to
<br /> dilutions factors None of the groundwater samples collected contained detectable
<br /> concentrations of ETBE, TBA, TAME, DIPE, 1,2-DCA, or EDB The sample collected from
<br /> well CW contained no detectable concentrations of petroleum hydrocarbons other than a low
<br /> concentration of MTBE Groundwater samples from wells MWI, MW3, and MW7 continue to
<br /> contain the highest concentrations of TPHg and BTEX A summary of analytical results is
<br /> presented in Table 1 Laboratory data sheets and chain-of-custody documentation are contained
<br /> in Attachment 2
<br /> GROUNDWATER FLOW DIRECTION
<br /> Water level measurements were collected from wells MW1 through MW10, and CW on
<br /> September 23, 2002 Water levels ranged from 23 47 to 27 68 feet below the tops of the well
<br /> casing elevations, representing an average decrease in the water table elevation of approximately
<br /> 1 33 feet since June 2002 The water level data were used to develop the groundwater elevation
<br /> contour map (Figure 3) Assuming that horizontal isotropic conditions prevail, groundwater in
<br /> the uppermost aquifer beneath the site flowed towards the northeast The average hydraulic
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