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yi l <br /> • <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 for the presence <br /> of separate-phase hydrocarbons (SPH), using either an electronic indicator and a clear TeflonO bailer or an oil- <br /> water interface probe Wells not containing SPH that do not have submerged screens are then sampled without <br /> purging Wells that have submerged screens are purged of approximately three casing volumes of water(or to <br /> dryness) using a centrifugal pump, gas displacement pump, or bailer Equipment and purging method used for <br /> the current sampling event is noted on the attached field data sheets During purging, temperature, pH, and <br /> electrical conductivity are monitored in order to document that these parameters are stable prior to collecting <br /> samples After purging,water levels are allowed to partially recover Groundwater samples (both purge and no <br /> . purge) are collected using a Teflon bailer, placed into appropriate EPA-approved containers, labeled, logged <br /> onto chain-of-custody 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), 8020, and 5030 These analyses were performed by utilizing a purge and trap extraction technique, <br /> with final detection was by gas chromatography using flame- and photo-ionization detectors The methods of <br /> analysis for the groundwater samples are documented in the certified analytical report The certified analytical <br /> report, chain-of-custody documentation,and field data sheets are presented as Attachment B <br />