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' 23 Chemical Distribution in Groundwater <br /> The groundwater monitor wells were developed and sampled by Canome on November 5, 1992 <br /> I Groundwater were samples p r analyzed for TPHg, BTEX, and EDB The only sample with petroleum <br />' hydrocarbons present above the laboratory detection limits during this event was from well W3 with <br /> 0 55 parts per billion (ppb) of xylenes <br /> I <br /> As of the third quarter of 1994, quarterly groundwater sampling was implemented at the request of <br /> the PHS/EHD 4n December 2, 1993 and July 28, 1994, the groundwater monitor wells were <br /> sampled by SEACOR Prior to sampling, depth to water in each groundwater monitor well was taken <br />' (Table 3) and subjective analyses performed The subjective analyses consisted of checking for <br /> floating product or a hydrocarbon sheen by lowering a clean teflon bailer down the well and <br /> Icollecting a sample at the groundwater-air interface Wells not containing floating product were <br /> I purged of approximately 3 to 5 volumes of water or until groundwater parameters of pH, <br /> temperature, and conductivity stabilized as measured by portable meters calibrated to a standard <br /> buffer and conductivity standard (Appendix A) Groundwater samples were then collected by <br /> lowering a clean disposable bailer into the well and collecting a representative sample of the <br /> Iformation water The groundwater sample was slowly transferred to laboratory-cleaned sample <br /> containers, sealed with teflon lined caps, and transferred to cooled storage The samples were then <br /> transported under suitable chain-of-custody to a State of California certified laboratory for the <br /> requested testing A groundwater sample from each monitor well was analyzed for TPHg and <br /> BTEX, by EPA Methods 8015, 8020 respectively <br /> IThe only sample with petroleum hydrocarbons present above the laboratory detection limits dunng <br /> the December 2, 1994 sampling event was from well W6 with 0 06 ppb toluene (Table 4) These <br /> Iconcentrations are well below the State maximum contaminant levels (MCL's) of 1750 ppb xylenes <br /> and 1000 ppb toluene in A Compilation of Water Quality Goals published by the CRWQCB-Central <br /> iValley Region Petroleum hydrocarbons were not reported above the laboratory method detection <br /> limits in groundwater samples collected dunng the July 1994 sampling event The laboratory results <br /> i <br />• <br /> i TOC1414 FRPA tiEALOR <br /> 4 • <br /> 1E00051101111 Augur j6 149E <br />