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l) � <br /> Mr Harlin Knoll <br /> Page 2 of 3 <br /> conductance, and pH were measured and recorded during the purging process All downhole <br /> equipment was decontaminated prior to and between each use by washing with a solution of <br /> Iaboratory-grade detergent and then double-rinsing with water Groundwater samples were <br /> collected using dedicated disposable bailers after physical parameters stabilized, and water <br /> levels recovered to at least 80% of pre-purged levels The samples were decanted into 40-m1 <br /> glass vials preserved with dilute hydrochloric acid The samples were subsequently placed to <br /> an ice chest refrigerated to a temperature of approximately 4°C <br /> The samples were transported to Argon Laboratories (ELAP #2359) under chain of custody <br /> protocol and analyzed for TPHg and BTEX utilizing EPA methods 8015B and 8021B, <br /> respectively Purged groundwater was contained in labeled Department of Transportation <br /> (DOT) approved drums pending disposal Copies of field purge logs and water level <br /> measurements are included in Attachment A <br /> Groundwater Analytical Results <br /> Elevated levels of dissolved gasoline constituents were detected in the groundwater samples <br /> collected from well MW5 Relatively low levels were detected in the samples collected from <br /> wells MW1 and MW4 <br /> Well MW5 contained TPHg at a concentration of 21,000 parts per billion (ppb), benzene at <br /> 1,900 ppb, toluene at 190 ppb, ethylbenzene at 170 ppb, and xylenes at 1,500 ppb Well <br /> MW1 contained TPHg at a concentration of 200 ppb, benzene at 0 5 ppb and xylenes at 3 0 <br /> ppb Only benzene (0 6 ppb) was detected in well MW4 Analytical results are summarized <br /> in Table 3 Laboratory data sheets and chain of custody documentation are included in <br /> Attachment B Figure 3 presents a benzene isoconcentration map utilizing the most recent <br /> analytical results Attachment C contains graphical representations of TPHg and benzene <br /> concentrations over time in site wells <br /> SUMMARY <br /> Groundwater at the site flowed in an east-northeast direction The potentiometric surface at <br /> the site rose an average of 0 90 feet The water level hes above the screened interval in all <br /> wells except well MW3 <br /> TPHg and BTEX were detected at elevated levels in well MW5 TPHg, benzene and xylenes <br /> were detected at low levels in well MW1 Benzene was the only chemical of concern detected <br /> in well MW4 The concentrations of benzene, ethylbenzene, and xylenes detected in wells <br /> MW 1 and MW4 were below the Maximum Contaminant Levels (MCLS) established by the <br /> State of California <br /> G\GROUNDMKNOWLES HAMaEPORTSIQMR12QM2003 doc <br />