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vaned Groundwater Monitonne Report
<br /> Former 6-Z Serve Location 100966
<br /> 2537 Waterloo Road
<br /> Stockton,California
<br /> Delta Project No RPMSO-966
<br /> • Page 2
<br /> 20 GROUNDWATER MONITORING DATA
<br /> 2.1 Groundwater Gauj!ing and Sam lm
<br /> Delta Environmental Consultants, Inc (Delta) performed groundwater monitoring activities at this site on
<br /> September 20, 2005 Prior to purging, the monitoring wells were gauged for liquid phase hydrocarbons
<br /> (LPH) and depth to water utilizing an oil water interface probe Groundwater ranged from 56 35 (MW-
<br /> 13) feet to 57 19 (MW-9) feet below top of casing No LPH was detected in any of the monitoring wells
<br /> during the September 20, 2005 gauging activities Depths to groundwater and groundwater elevations are
<br /> presented in Table 1, Groundwater Analytical Data
<br /> Prior to sampling, monitoring wells MW-9 through MW-17, EX-1, VW-1 and VW-2 were purged by
<br /> removing approximately three well volumes of water with a submersible pump Once the wells had been
<br /> purged, they were sampled utilizing disposable polyurethane bailers No purge grab samples were taken
<br /> from monitoring wells MW-1 through MW-8 using disposable dual-valve polyurethane bailers The
<br /> groundwater samples collected were decanted into properly labeled, laboratory prepared sample
<br /> containers and placed on ice for storage prior to transporting to the laboratory The samples were
<br /> transported, under strict chain-of-custody protocols, to Kff Analytical LLC of Davis, California, for
<br /> analysis of benzene, toluene, ethyl-benzene, total xylenes (BTEX), total petroleum hydrocarbons (TPH)
<br /> in the gasoline range, methyl tert butyl ether (MTBE), diisopropyl ether (DIPE), ethyl tert butyl ether
<br /> (ETBE), tert-amyl methyl ether (TAME), tert butyl alcohol (TBA), methanol, ethanol, 1,2-
<br /> Dichloroethane, and 1,2-Dibromoethane by EPA Method 8260B MW-6 was covered by a gravel pile and
<br /> was not sampled, while the location of VW-3 could not be determined
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<br /> 22 Analytical Data
<br /> Laboratory chemical analysis of the groundwater samples collected on September 20, 2005 indicates that
<br /> benzene concentrations have remained below laboratory reporting limits in monitoring wells MW-1,
<br /> MW-2, MW-3, MW-4, MW-5, MW-7, MW-8, MW-13, MW-15, MW-16 and MW-17, have decreased in
<br /> monitoring wells MW-91 MW-10, MW-12, MW-14, VW-1, VW-2 and EX-1, and have increased in
<br /> monitoring wells MW-11 and VW-1 The highest benzene concentration was 3,000 µg/L in monitoring
<br /> well VW-1 Concentrations of TPHg were detected in wells MWA, MW-3, MW-7, MW-9 through MW-
<br /> 17, EX-1, VW-1 and VW-2 Wells MW-2, MW-4, MW-5, and MW-8 had concentrations that were
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<br /> below the laboratory reporting limits MTBE concentrations were below laboratory reporting limits in
<br /> monitoring wells MW-2, MW3, MW-4, MW-8, MW-15 and MW-17 Levels of MTBE have decreased in
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<br /> K Morking\Prolect Files1100966 Stockton 2537 Waterloo Road1GWM130051100966 3rd05QMR doc
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