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41 u <br /> ATTACHMENT B <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> Sampling equipment is thoroughly cleaned prior to each sample The sampling procedure for <br /> each well includes measuring the water level and checking for the presence of separate-phase <br /> hydrocarbons (SPH), using either an electronic indicator and a clear Teflon® bailer, or an oil- <br /> water interface probe Wells not containing SPH that do not have submerged screens are <br /> then sampled without purging Wells that have submerged screens are purged of <br /> approximately three casing volumes of water (or to dryness) using a clean centrifugal pump, <br /> gas displacement pump, or bailer The equipment and purging method used for the current <br /> sampling event are noted on the attached field data sheets During purgipg, temperature, pH, <br /> and electrical conductivity are monitored in order to document that these parameters are <br /> stable prior to collecting samples After purging, water levels are allowed to partially <br /> recover Groundwater samples (both purge and no purge) are collected using a clean Teflon <br /> bailer, placed into appropriate EPA-approved containers, labeled, logged onto chain-of- <br /> custody documents, and transported on ice to a California State-certified laboratory <br /> Laboratory Procedures <br /> Selected water samples collected will be analyzed for the presence of total petroleum <br /> hydrocarbons calculated as gasoline and diesel, benzene, toluene, ethylbenzene, and xylenes <br /> using modified EPA Methods 8015 and 8020 Fuel oxygenates will be analyzed by EPA <br /> Method 8260B Standard methods were used for inorganic parameters including DO, ORP, <br /> conductivity, pH, total alkalinity, dissolved iron, manganese, sulfate, nitrate, ferrous iron, <br /> TOC and COD <br /> Purge Water <br /> Water generated during sampling of the groundwater wells will be temporarily stored in <br /> DOT-approved 55-gallon drums pending transport by the disposal contractor to an <br /> appropriate disposal or treatment facility <br /> i <br />