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I f ATTACHMENT A FIELD PROCEDURES AND LABORATORY ANALYSIS r Groundwater Sampling Procedures i The a oundwater sampling procedure consisted of first measuring the water level in each well with an electronic water level indicator, and checking each well for the presence of separate-phase hydrocarbons using a clear Teflon bailer. None of the the wells contained separate-phase hydrocarbons,and all wells were than purged of approximately four casing volumes of water using a 2-inch diameter centrifugal pump. During purging, temperature, pH, and electrical conductivity were monitored in order to document that these parameters were stable prior to sample collection. After purging, the.water - levels were allowed to partially stabilize. Groundwater samples were -' collected using a Teflon bailer, placed into appropriate EPA-approved containers, labelled, logged onto chain-of-custody documents, and transported on ice to a California State-certified laboratory. The chain-of-custody documentation is attached. r LaboratoryAnalysis Groundwater samples were analyzed in the laboratory for the presence of total petroleum hydrocarbons calculated as gasoline (TPH-gasoline), and benzene, toluene, ethvlbenzene, and xylenes (BTEX compounds). Extraction was performed by the purge-and-trap technique, EPA Method 5030. Analysis for TPH-gasoline was performed according to the DHS LUFT method, and anat-sis for B EX compounds was by EPA Method 8020. Final detection,was by gas chromatography using a flame-ionization detector and a photo- ionization detector. Groundwater samples were also analyzed for semi- arld non-volatile hydrocarbons calculated as diesel (TPH-diesel) by the DHS LUFT method. All analyses were performed by a California State-certified laboratory. 3100102/409tDecember 31. 1991 } — a