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41 <br /> • <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 <br /> 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 TeflonO bailer or an oil-water <br /> interface probe Wells not containing SPH that do not have submerged screens are then sampled <br /> without purging Wells that have submerged screens are purged of approximately three casing <br /> volumes of water (or to dryness) using a submersible pump, centrifugal pump, gas displacement <br /> pump, or bailer The equipment and purging method used for the current sampling event are noted <br /> on the attached field data sheets During purging, temperature, pH, and electrical conductivity are <br /> monitored in order to document that these parameters are stable prior to collecting samples After <br /> purging, water levels are allowed to partially recover Groundwater samples (both purge and no- <br /> purge) are collected using a disposable Teflon& bailer, placed into appropriate EPA-approved <br /> containers, labeled, logged onto chain-of-custody documents, and transported on ice to a California <br /> state-certified laboratory <br /> Laboratory Procedures <br /> The groundwater samples are analyzed for the presence of TPHg, benzene, toluene, ethylbenzene, <br /> xylenes (total), and MtBE using EPA Methods 8095 (modified) and 8020, and fuel oxygenates using <br /> EPA Method 82608 The methods of analysis for the groundwater samples are documented in the <br /> certified laboratory analytical reports The certified laboratory analytical reports, chain-of-custody <br /> documentation, and field data 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- <br /> mounted water tank The water is transported to ARCO's holding facility in West Sacramento, <br /> California, for temporary storage Water is then transported by Integrated Waste Management (IWM) <br /> to Seaport Environmental in Redwood City, California for disposal <br />