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<br /> A S S d C 1 A T E S I N C
<br /> Additionally, in December 2001 an ATC geologist supervised sed the advancement of five
<br /> Geoprobe borings, S1312 to S1316 to a depth of approximately 25 feet bgs Three additional
<br /> offsite borings were advanced to depths of approximately 42 feet bgs and completed as
<br /> groundwater monitoring wells MW8 through MW10 Field activities and analytical results were
<br /> detailed in ATC's Offsite Subsurface Investigation Report, dated April 24, 2003
<br /> QUARTERLY GROUNDWATER MONITORING ACTIVITIES
<br /> On June 8, 2004, ATC personnel collected groundwater samples from monitoring wells MWI
<br /> through MW 10, V W 1, VW2, and CW The locations of the monitoring wells are shown on
<br />' Figure 2 Prior to collection of groundwater samples, the depth to water was measured in the
<br /> wells and the pH, electrical conductivity, and temperature were measured in purged groundwater
<br /> and recorded A minimum of three well casing volumes was purged from each well prior to
<br />' sampling with the exception of well VW2 Well VW2 was purged dry after removing
<br /> approximately 2 8 well casing volumes The wells were allowed to recover and samples were
<br /> collected from each well using dedicated disposable balers Groundwater well purge and sample
<br /> 1 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
<br /> 8015B, benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8021B, and methyl
<br /> tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETBE), tertiary butyl alcohol (TBA),
<br /> tertiary amyl ether (TAME), di-isopropyl ether (DIPE), 1,2-dichloroethane (1,2-DCA), and ethyl
<br /> dibrom>de (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 /> groundwater samples collected from wells MW1, MW6, MW7, VW1, and VW2 The
<br /> groundwater samples collected from wells MW2, MW4, MW5, MW6, MW7, MW9, CW, and
<br /> VW2 contained low concentrations of MTBE ranging from 0 6 micrograms per liter (ug/1) to 10
<br />' ug/i None of the groundwater samples collected contained detectable concentrations of ETBE,
<br /> TBA, TAME, DIPE, 1,2-DCA, or EDB The samples collected from MW3, MW8 and MWIO
<br /> contained no detectable concentrations of any of the analytes of interest
<br />' Theroundwater samples collected >n June 2004 from wells MW2 MW4 through g P MW7, MW9,
<br /> and CW contained slightly higher concentrations of MTBE than the samples collected in March
<br /> 2004, but are below the Maximum Contamination Limit (MCL) for groundwater and within
<br /> historical ranges A summary of analytical results is presented in Table 1 Groundwater
<br />' laboratory data sheets and chain-of-custody documentation are contained in Attachment 2
<br /> s lenviro1625961quart1yl2gr-2004 doc 3
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