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<br /> A S S O C I A T E S I N C
<br /> QUARTERLY GROUNDWATER MONITORING ACTIVITIES
<br /> On June 9, 2003, ATC personnel collected groundwater samples from monitoring wells MW1
<br /> through MW 10 and CW The locations of the monitoring wells are shown on Figure 2 Prior to
<br /> collection of groundwater samples, the depth to water, pH, electrical conductivity, and
<br /> temperature were measured in the monitoring wells and recorded A minimum of three well
<br /> casing volumes was purged from each well prior to sampling The wells were allowed to recover
<br /> and samples were collected from each well using dedicated disposable bailers After groundwater i
<br /> samples were collected, dissolved oxygen concentrations were measured in each well
<br /> 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 analyses of TPHg by EPA method 801513,
<br /> benzene toluene eth lbenzene xylenes BTEX b EPA method 802113 and methyl tertiary
<br /> > Y � Y (BTEX) Y � Y
<br /> butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), tertiary butyl alcohol (TBA), tertiary amyl
<br /> ether (TAME), di-isopropyl ether (DIPS), 1,2-d>chloroethane (1,2-DCA), and ethyl d>brom>ide
<br /> (EDB) by EPA method 8260B
<br /> Groundwater Analytical Results
<br /> TPHg and/or BTEX constituents were detected at or above laboratory reported detection limits in
<br /> the samples collected from wells MW1, MW3, MW5, MW6, and MW7 The groundwater
<br /> samples collected from wells MW2, MW3, MW4, MW5, MW6, MW7, MW9, MW10, and CW
<br /> contained low concentrations of MTBE ranging from 0 6 parts per billion (ppb) to 12 ppb The
<br /> groundwater samples collected from MW1 and MW8 did not contain detectable concentrations
<br /> of MTBE, but the detection limits in the sample collected from MW 1 were elevated due to
<br /> dilution factors None of the groundwater samples collected contained detectable concentrations
<br /> of ETBE, TBA, TAME, DIPE, 1,2-DCA, or EDB, with the exception of the groundwater sample
<br /> collected from MW7 TBA was detected in this sample at a concentration of 21 ppb The samples
<br /> collected from MW2, MW4, MW9, MW10, and CW contained no detectable concentrations of
<br /> petroleum hydrocarbons other than low concentrations of MTBE
<br /> The groundwater sample collected in June 2003 from MW3, located near the vapor extraction
<br /> wells, contained significantly lower concentrations of TPHg, BTEX, and MTBE, at least one
<br /> order of magnitude less, than the sample collected in March 2003 Groundwater samples
<br /> collected from MW 1 and MW7 contained slightly increased concentrations of TPHg. and BTEX
<br /> with respect to the samples collected from these wells in March 2003, but are within historical
<br /> ranges Concentrations in the remaining wells generally were the same as those detected in
<br /> March 2003 A summary of analytical results is presented in Table 1 Groundwater laboratory
<br /> data sheets and chain-of-custody documentation are contained in Attachment 2
<br /> W
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