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7 � <br /> i <br /> i <br /> ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> E <br /> Sampling Procedures <br /> t <br /> The sampling procedure for each well consists first of measuring the water level and checking j <br /> for the presence of separate-phase hydrocarbons (SPH), using either an electronic indicator <br /> and a clear Teflon@ bailer or an oil-water interface probe. Wells not containing SPH are then <br /> purged of approximately three casing volumes of water (or to dryness) using a centrifugal <br /> pump, gas displacement pump, or bailer. Equipment used for the current sampling event is <br /> noted on the attached field data sheets. During purging, ,tem eratureH, and electrical <br /> p p � <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 /> 1 <br /> samples are collected using a Teflon bailer, placed into appropriate EPA-approved <br /> containers, labeled, logged onto chain-of-custody documents, and transported on ice to a <br /> California state-certified laboratory. <br /> Laboratory Procedures <br /> Groundwater samples collected were analyzed for the presence of total petroleum <br /> hydrocarbons calculated as gasoline, benzene, toluene, ethylbenzene and xylenes using EPA I <br /> Method 8015GRQ/8021. The five gasoline oxygenates (MtBE, DIPE, ETBE, TAME and � <br /> TBA) were analyzed by EPA Method 8260B. A ¢n.#/I i, w pe a&4( E DQ <br /> i <br /> !Le <br /> F <br /> .kk} <br /> Shaw Environmental,Inc. k <br /> NasacDP120031Prj1880\8800401 A.3ae.doc <br /> i <br /> A-1 . <br />