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' purged from each well prior to sampling The wells were allowed to recover and samples were collected
<br /> from each well using dedicated disposable bailers Groundwater well purge and sample logs are
<br /> r� contained in Attachment 1
<br /> ' Theoundwater samples collected from each well were submitted to State-certified Argon Laboratories
<br /> 1�' p g ,
<br /> 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 802113,
<br /> and methyl tertiary butyl ether (MTBE), ethyl tertiary butyl ether (ETRE), tertiary butyl alcohol (TBA),
<br /> tertiary amyl ether (TAME), dt-isopropyl ether (DIPE), 1,2-dichloroethane (1,2-DCA), and ethyl
<br /> dibromide(EDB) by EPA Method 8260B
<br /> Groundwater Flow Direction
<br /> DTW was initially measured in MW 1 through MW 10, VW2, and CW on September 27, 2005 The
<br /> DTW meter was later determined to be damaged by ATC personnel Subsequently ATC returned to the
<br /> ' site on October 7, 2005 and measured DTW in MW1, MW2, MW4, MW5, MW7 through MW10, VW1,
<br /> VW2, and CW DTW was not measured in MW3 and MW6 on October 7, 2005 since the wells were
<br /> inaccessible The DTW measurements collected on October 7, 2005 were used to determine the
<br /> ' groundwater water gradient On October 7, 2005, water levels ranged from 23 60 to 27 73 feet below the
<br /> tops of the well casing elevations, representing an average decrease in the water table elevation of
<br /> approximately 0 15 feet since June 2005 The DTW data for MWI, VW1, and VW2 were not used for
<br /> calculating the change to 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 /> groundwater elevation contour map (Figure 3) Shallow groundwater beneath the site flowed toward the
<br /> northeast The average hydraulic gradient on October 7, 2005, was calculated to be approximately 0 007
<br /> ft/ft or approximately 37 ft/mile A summary of groundwater monitoring data is presented in Table 1
<br /> 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 MW 1, MW5,MW6, MW7, and VW2
<br /> 1 The groundwater samples collected from MW2, MW4, MW6, MW7, MW9, and CW contained low
<br /> concentrations of MTBE ranging from 0 7 micrograms per liter (ug/l) to 3 3 ug/l TBA was detected in
<br /> the groundwater sample from MW2 at a concentration of 27 ug/l The analyte 1,2-DCA was detected In
<br /> the groundwater sample collected from MW8 at a concentration of 1 3 ug/l None of the groundwater
<br /> samples collected contained detectable concentrations of ETBE, TAME, DIPS, or EDB According to
<br /> ' the analytical lab, the samples were double checked by running through a second machine and both runs
<br /> yielded similar analytical results
<br /> A summary of analytical results is presented in Table 2 Groundwater laboratory data sheets and cham-
<br /> tof-custody documentation are contained in Attachment 2
<br /> ' REMEDIATION SYSTEM
<br /> Remediation System Background
<br /> ' The installation and startup of the SVEIAS 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 lenvjro1625961quart1yl3gr-2005 doc 3 ATC ASSOCIATES INC
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