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T, <br /> ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> Sampling equipment is thoroughly cleaned prior to each sample.The sampling procedure for each well includes <br /> measuring the water level and checking for the presence of separate-phase hydrocarbons(SPH), using either an <br /> electronic indicator and a clear TeflonO bailer or an oil-water interface probe. Wells not containing SPH that <br /> do not have submerged screens are then sampled without purging. Wells that have submerged screens are <br /> purged of approximately three casing volumes of water (or to dryness) using a clean submersible pump, <br /> centrifugal pump, gas displacement pump, or bailer. The equipment and purging methods used for the current <br /> sampling event are noted on the attached field data sheets. During purging, temperature, pH, and electrical <br /> conductivity are monitored in order to document that these parameters are stable prior to collecting samples. <br /> After purging, water levels are allowed to partially recover. Groundwater samples (both purge and no-purge) <br /> are collected using a.clean Teflon@ bailer, placed into appropriate EPA-approved containers, labeled, logged <br /> onto chain-of-custody documents,and transported on ice to a California state-certified laboratory. <br /> Laboratory Procedures <br /> The groundwater samples are analyzed for the presence of TPHg, benzene, toluene, ethylbenzene, xylenes <br /> (total), and MtBE using EPA Methods 8015 (modified) and 8020, and fuel oxygenates using EPA Method <br /> 8260A. The methods of analysis for the groundwater samples are documented in the certified laboratory <br /> analytical report. The certified laboratory analytical report, chain-of-custody documentation, and field data <br /> sheets are presented as Attachment B. <br /> Purge and Rinsate Water Disposal <br /> Water generated during well sampling and equipment cleaning is pumped into a SECOR truck-mounted water <br /> tank. The water is .transported to ARCO's holding facility in West Sacramento, California, for temporary <br /> storage. Water is then transported by Integrated Waste Management (IWM) to Seaport Environmental in <br /> Redwood City,Califomia for disposal. <br />