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ATTACHMENT A <br /> FIELD AND LABORATORY PROCEDURES <br /> Sampling Procedures <br /> Sampling equipment is throughly cleaned prior to each sampling event The sampling procedure for each well <br /> consists first of measuring the water level and checking for the presence of separate-phase hydrocarbons(SPH), <br /> using either an electronic indicator and a clear Teflon® bailer or an oil-water interface probe Wells not <br /> containing SPH that do not have submerged screens are then sampled without purging Wells that have <br /> submerged screens are purged of approximately three casing volumes of water(or to dryness)using a centrifugal <br /> pump, gas displacement pump, or bailer The 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 conductivity are <br /> monitored in order to document that these parameters are stable prior to collecting samples After purging, <br /> water levels are allowed to partially recover Groundwater samples (both purge and no purge) are collected <br /> using a Teflon bailer, placed into appropriate EPA-approved containers, labeled, logged onto chain-of-custody <br /> documents,and transported on ice to a California State-certified laboratory <br /> Laboratory Procedures <br /> The groundwater samples were analyzed for the presence of total petroleum hydrocarbons calculated as <br /> gasoline, benzene, toluene, ethylbenzene, xylenes, and methyl tertiary butyl ether by EPA Methods 8015 <br /> (modified) and 8020 One sample was analyzed for oil and grease using EPA Method 418 1 The methods of <br /> analysis for the groundwater samples are documented in the certified laboratory analytical report The certified <br /> laboratory analytical report, chain-of-custody documentation, and field data sheets are presented as Attach- <br /> ment B <br /> Purge and Rinsate Water Disposal <br /> Water generated during well sampling and equipment cleaning is pumped into a SECOR truck mounted water <br /> tank The water is transported to ARCO's holding facility in West Sacramento, California, for temporary <br /> storage Water is then transported by Integrated Waste Management (IWM) to Seaport Environmental in <br /> Redwood City,California for disposal <br />