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1C'— VV
<br /> T9
<br /> A S S O C I A T E S I N C
<br /> Remediation Plan, Farmer Property, 610 North Hunter Street, Stockton, California, dated March
<br /> 27, 2002
<br /> QUARTERLY GROUNDWATER MONITORING ACTIVITIES
<br />' On March 6 and 7, 2003, ATC Associates personnel collected groundwater samples from
<br /> monitoring wells MW1 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 (DIPE), 1,2-dichloroethane (1,2-DCA), and ethyl dibromide (EDB)
<br /> utilizing EPA method 8260
<br /> Groundwater 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, MW3, MW4, MW5, MW6, MW7, and CW contained low concentrations of
<br /> MTBE ranging from 2 4 parts per billion (ppb) to 15 ppb The groundwater samples collected
<br /> from wells MW 1, MW8, MW9, and MW 10 did not contain detectable concentrations of MTBE,
<br /> but the detection limits in the sample in well MW1 were elevated due to dilution factors None
<br /> of the groundwater samples collected contained detectable concentrations of ETBE, TBA,
<br /> TAME, DIPE, 1,2-DCA, or EDB The sample collected from well CW contained no detectable
<br /> concentrations of petroleum hydrocarbons other than a low concentration of MTBE
<br /> Groundwater samples collected in March 2003 from wells MW1 and MW3, located near the
<br />' vapor extraction wells, contained concentrations of TPHg and BTEX at least one order of
<br /> magnitude less than samples collected in December 2002 Groundwater samples collected from
<br /> MW7 also contained lower concentrations of TPHg and BTEX than in December 2002 A
<br /> summary of analytical results is presented in Table 1 Groundwater laboratory data sheets and
<br /> chain-of-custody documentation are contained in Attachment 2
<br /> w Iwordpro1625961quart1yligr-2003 doc 3
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