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' Second Quarter 2004 Groundwater Report
<br /> 8200 N Highway 99, Stockton, CA
<br /> Page 3 of 6
<br />' parameters stabilized and water levels in the wells recovered to at least 80% of their respective
<br /> pre-purged levels, with the exception of well V W 1 which had very little water in the well The
<br /> samples were temporarily stored in an ice chest refrigerated to a temperature of approximately
<br />' 4°C and delivered under chain of custody protocol to Argon Laboratories (ELAP 42359) for
<br /> analysis Purged groundwater was contained in appropriately labeled DOT-approved 55-gallon
<br /> drums in accordance with 49 CFR part 172 and 40 CFR part 262, and will eventually be
<br />' processed through the groundwater treatment system Copies of field data sheets and purge logs
<br /> are included in Attachment C
<br />' Argon Laboratories analyzed all groundwater samples collected for total petroleum hydrocarbons
<br /> as gasoline (TPHg) using EPA 801513, benzene, toluene, ethylbenzene, and total xylenes (BTEX)
<br /> using EPA 802113, and oxygenated gasoline additives, ethylene dibromide (EDB), 1,2-
<br />' dichloroethane (1,2-DCA), ethanol, and methanol using EPA 8260B
<br /> No gasoline constituents were detected in the groundwater samples collected from wells MW6,
<br />' MW7, MW8, MW 10, MW 11, MW 12, or MW 14B in June 2004
<br /> TPHg and BTEX constituents were detected in groundwater samples collected from wells MW1,
<br />' MW2 and VW1 in June 2004 Well MW1 was not analyzed for TPHg, however, benzene was
<br /> detected at 1,600 ppb, toluene at 2,500 ppb, ethylbenzene at 160 ppb, and xylenes at 760 ppb Well
<br /> MW2 contained TPHg at 210 ppb, benzene at 7 4 ppb and xylenes at 3 8 ppb Well VW1
<br /> contained TPHg at 9,500 ppb, benzene at 3,600 ppb, toluene at 1,700 ppb, ethylbenzene at 370 ppb,
<br /> and xylenes at 1,800 ppb
<br />' MTBE was present in wells MW1, MW2, MW3, MW4, MW5, MW913, MW13C, and VW1 at
<br /> concentrations of 3,600 ppb, 120 ppb, 1,200 ppb, 8,600 ppb, 51 ppb, 0 6 ppb, 25 ppb and 8,800
<br /> ppb, respectively No MTBE was detected in samples collected from wells MW6, MW7, MW8,
<br />' MW 10, MW 11, MW 12 or MW I4 Well MW 12 had previously contained MTBE at between
<br /> 1,500 and 2,500 ppb
<br />' Table 5 summarizes groundwater analytical results Figures 3 and 4 present isoconcentration
<br /> maps of MTBE and benzene in the A Zone, respectively, from the June 2004 data The figures
<br /> include analytical results of groundwater samples collected from newly installed wells MW 15 and
<br />' MW 16, which is discussed in Section 4 0 of this report Attachment D contains laboratory reports
<br /> and chain-of-custody documentation for groundwater samples collected from wells MW2
<br /> through MW 13 C and V W 1 in June 2004 Attachment E contains graphs of TPHg, benzene, and
<br /> MTBE concentrations of over time in all site wells
<br /> 3.3 Domestic Well Sampling and Analysis
<br /> At the direction of EHD in a letter dated October 10, 2003, Ground Zero collected water samples
<br /> from eight nearby domestic wells, including the site facility well The samples were collected from
<br /> either a sample port at the wellhead or from the nearest available sampling location (i e garden
<br /> hose) Samples were collected after the pump was turned on for approximately 15 minutes The
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