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ATTACHMENT A FIELD AND LABORATORY PROCEDURES Sampling Procedures Sampling equipment is thoroughly cleaned prior toe ach sample The sampling procedure for each well includes measuring the water level and checking for the presence of separate-phase hydrocarbons (SPH), using either an electronic indicator and a clear Teflon® bailer or an oil-water interface probe Wells not containing SPH that do not have submerged screens are then sampled without purging Wells that have submerged screens are purged of approximately three casing volumes of water (or to dryness) using a submersible pump, centrifugal pump, gas displacement pump, or bailer The equipment and purging method used for the current sampling event are noted on the attached field data sheets During purging, temperature, pH, and electrical conductivity are monitored in order to document that these parameters are stable prior to collecting samples After purging, water levels are allowed to partially recover Groundwater samples (both purge and no purge) are collected using a disposable Teflon batter, placed into appropriate EPA-approved containers, labeled, logged onto chain- of-custody documents,and transported on ice to a California State-certified laboratory Laboratory Procedures The groundwater samples were analyzed for the presence of total petroleum hydrocarbons calculated as gasoline, benzene, toluene, ethylbenzene, xylenes, and methyl tertiary butyl ether by EPA Methods 8015 (modified) and 8020 These analyses were performed by utilizing a purge and trap extraction technique, with final detection was by gas chromatography using flame- and photo-ionization detectors Fuel oxygenates were analyzed by EPA Method 8260A The methods of analysis for the groundwater samples are documented in the certified laboratory analytical report The certified laboratory analytical report, chain-of-custody documenta- tion,and field data sheets are presented as Attachment B Purge and Rinsate Water Disposal Water generated during well sampling and equipment cleaning is pumped into a SECOR truck mounted water tank The water is transported to ARCO's holding facility in West Sacramento, California, for temporary storage Water is then transported by Integrated Waste Management (IWM) to Seaport Environmental in Redwood City,California for disposal