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• STANDARD OPERATING PROCEDURE QUARTERLY GROUNDWATER SAMPLING Gettler-Ryan field personnel adhere to the following procedures for the collection and handling of groundwater samples prior to analysis by the analytical laboratory Prior to sample collection, the type of analysis to be performed is determined Loss pevention of volatile compounds is controlled and sample preservation for subsequent analysis is maintained. Prior to sampling, the presence or absence of free -phase hydrocarbons is deternuned using a MMC fleu-dip interface probe Product thickness, if present, is measured to the nearest 0 01 foot and is noted in the field notes In addition, static water level measurements are collected with the interface probe and are also recorded in the field notes. After water levels are collected and prior to sampling, each well is purged a minimum of three well casing volumes of water using pre --cleaned pumps (stack, suction, Grundfos), or polyvinyl chloride bailers Temperature, pH and electrical conductivity are measured a minimum of three times during purging. Purging continues until these parameters stabilize. Groundwater samples are collected using Chevron -designated disposable bailers. The water samples are transferred from the bailer into appropriate containers Pre preserved containers, supplied by analytic laboratories, are used when possible When pre -preserved containers are not available, the laboratory is instructed to preserve the sample as appropriate Duplicate samples are collected for the laboratory to use in maintaming quality assurance/quality control standards The samples are labeled to include the ,lob number, sample identification, collection date and time, analysis, preservative (if any), and the sample collector's initials The water samples are placed in cooler maintained at a C for transport to the laboratory Once collected m the field, all samples are maintained under chain of custody until delivery to the laboratory. The chain of custody document includes the job number, type of preservation, if any, analysis requested, sample identification, date and time collected and the sample collector's name The chain of custody is signed and dated (including hme of transfer) by each person who receives or surrenders the samples, beginning with the field personnel and ending with the laboratory personnel. A laboratory -supplied trip blank accompanies each sampling set. For sampling sets greater than 20 samples, 5 % trip blanks are included The trip blank is analyzed for some or all of the same compounds as the groundwater samples. As requested by Chevron USA Products Company, the purge and decontamination water generated during sampling activities is taken to Chevron's Richmond Refinery for disposal.