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<br /> 1 temperature were measured in groundwater purged from the monitoring wells, and visual observations
<br /> regarding turbidity were recorded A minimum of three well casing volumes was purged from each well
<br /> 1 prior to sampling The wells were allowed to recover and samples were collected from each well using
<br /> dedicated disposable bailers 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 Laboratories,
<br /> 1 Inc (Environmental Laboratory Accreditation Program Certificate No 2359) for chemical analyses of
<br /> TPHg by EPA Method 801513, benzene, toluene, ethylbenzene, xylenes (BTEX) by EPA Method 8021 B,
<br /> and methyl 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 /> dibromide (EDB)by EPA Method 8260B
<br /> Groundwater Flow Direction
<br /> 1
<br /> DTW was initially measured in MWI, MW2, MW4, MW5, MW8, MW9, MWIO, VW2, and CW on
<br /> ' December 28, 2005 DTW was not measured in MW3, MW6, and MW7 since the wells were
<br /> inaccessible The DTW measurements collected on December 28, 2005 were used to determine the
<br /> groundwater water gradient On December 28, 2005, water levels ranged from 24 32 to 28 27 feet below
<br /> the tops of the well casing elevations, representing an average decrease in the water table elevation of
<br /> approximately 0 26 feet since October 2005 The DTW data for MWI, VW1, and VW2 were not used
<br /> for calculating the change in average groundwater elevation beneath the site since the VES extracts
<br /> groundwater from these wells while in operation The water level data were used to develop a
<br /> 1 groundwater elevation contour map (Figure 3) Shallow groundwater beneath the site flowed toward the
<br /> northeast The average hydraulic gradient on December 28, 2005, was calculated to be approximately
<br /> 0 007 ft/ft or approximately 37 ft/mile A summary of groundwater monitoring data is presented in Table
<br /> 1 i
<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 MWI, MW2, MW4, VW1, and VW2
<br /> 1 The groundwater samples collected from MWI, MW2, MW4, and MW9 contained low concentrations of
<br /> MTBE ranging from 0 8 micrograms per liter (ug/l) to 120 ug/l MTBE was detected above laboratory
<br /> 1 method detection limits for the first time in MWI TBA was detected in the groundwater sample from
<br /> MW2 at a concentration of 48 ug/l The analyte 1,2-DCA was detected in the groundwater sample
<br /> collected from MWI and MW8 at concentrations of 63 ug/l and 13 ug/l, respectively None of the
<br /> 1 groundwater samples collected contained detectable concentrations of ETRE, TAME, DIPS, or EDB
<br /> According to the analytical lab, the samples were double checked by running through a second machine
<br /> and both runs yielded similar analytical results
<br /> ' A summary of analytical results is presented in Table 2 Groundwater laboratory data sheets and chain-
<br /> of-custody documentation are contained in Attachment 2
<br /> 1 REMEDIATION SYSTEM
<br /> Remediation System Background
<br /> 1 The installation and startup of the SVE/AS remediation system at the site is detailed in ATC's
<br /> Remediation System Installation Report for the Farmer Property, 610 North Hunter Street, Stockton,
<br /> California, dated April 8, 2003 Figure 4 shows the layout of the remediation system equipment compound,
<br /> S lenvzro1625961quardyl4gr-2005 doe 3 ATC ASSOCIATES INC
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