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ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> The sampling procedure for each well consists first of measuring the water level and <br /> checking for the presence of separate-phase hydrocarbons (SPH), using either an electronic <br /> indicator and a clear TeflonO bailer or an oil-water interface probe. Wells not containing <br /> SPH are then purged of approximately three casing volumes of water(or to dryness) using a <br /> centrifugal pump, gas displacement pump, or bailer. Equipment used for the current <br /> sampling event is noted on the attached field data sheets.7-During purging, 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 are collected using a Teflon bailer, placed into appropriate <br /> EPA-approved containers, labeled, logged onto chain-of-custody documents, and transported <br /> on ice to a California State-certified laboratory. <br /> Laboratory Procedures <br /> Groundwater samples collected were analyzed for the presence of total petroleum <br /> hydrocarbons calculated as gasoline using modified EPA Method 8015. Groundwater <br /> samples collected were analyzed for the presence of benzene, toluene, ethylbenzene and <br /> xylenes, using modified EPA Method 8020. The five gasoline oxygenates (MtBE, DIPE, <br /> ETBE, TAME and TBA)were analyzed by EPA Method 8260. <br /> S <br /> N:\Tancfpl\Projects\Projects\880\040\1 a101071880040_1 gOl.doc 02/20/01 F <br /> A - 1 <br />