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4j �) <br /> ATTACHMENT B <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> The sampling procedure for each well consists first of measuring the water level and checking <br /> for the presence of separate-phase hydrocarbons (SPH), using either an electronic indicator and a <br /> clear TeflonO bailer or an oil-water interface probe Wells not containing SPH that do not have <br /> 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 centrifugal pump, <br /> gas displacement pump, or bailer Equipment and purging method used for the current sampling <br /> event is 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 <br /> . collecting samples After purging, water levels are allowed to partially recover Groundwater <br /> samples (both purge and no purge) are collected using a Teflon bailer, placed into appropriate <br /> EPA-approved containers, labeled, logged onto chain-of-custody documents, and transported on <br /> ice to a California State-certified laboratory <br /> Laboratory Procedures <br /> The groundwater samples were analyzed for the presence of total petroleum hydrocarbons <br /> calculated as gasoline, benzene, toluene, ethylbenzene, xylenes, and methyl tertiary butyl ether <br /> by EPA Methods 8015 (modified), 8020, and 5030 These analyses were performed by utilizing <br /> a purge and trap extraction technique, with final detection was by gas chromatography using <br /> flame- and photo-ionization detectors The methods of analysis for the groundwater samples are <br /> documented in the certified analytical report The certified analytical report, chain-of-custody <br /> documentation, and field data sheets are presented as Attachment B <br /> 7C600-019-01/2Q9S A- i September 25 1998 <br />