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STANDARD OPERATING PROCEDURE - • GROUNDWATER SAMPLING Gettler-Ryan Inc field personnel adhere to the following procedures for the collection and handling of groundwater samples prior to analysis by the analytical Iaboratory Prior to sample collection, the type of analysis to be performed is determined Loss prevention 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 determined using an interface probe Product thickness, if present, is measured to the nearest 0 01 foot and is noted in the field notes In addition, all depth to water level measurements are collected with a static water level indicator and are also recorded in the field notes, prior to purging and sampling any wells After water levels are collected and prior to sampling, if purging is to occur, each well is purged a minimum of three well casing volumes of water using pre-cleaned pumps (stack, suction, Grundfos), or disposable bailers Temperature, pH and electrical conductivity are measured a minimum of three times during the purging Purging continues until these parameters stabilize Groundwater samples are collected using disposable bailers The water samples are transferred from the bailer into appropriate containers Pre-preserved containers, supplied by analytical laboratories, are used when possible When pre-preserved containers ale not available, the laboratory is instructed Mto preserve the sample as appropriate Duplicate samples aie collected for the laboratory to use in maintaining quality assurance/quality control standards The samples are labeled to include the job number, sample identification, collection date and time, analysis, preservation (if any), and the ' sample collector's initials The water samples are placed in a cooler, maintained at 4°C foi transport to the laboratory Once collected in the field, all samples are maintained under chain of custody until ' delivered to the laboratory The chain of custody document includes the fob 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 time of transfer) by each person who receives of surrenders the samples, beginning with the field persoilriel and ending with the laboratory personnel A laboratory supplied trip blank accompanies each sampling set and is labeled QA 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 Unocal Corporation, the purge water and decontamination water generated dwing sampling activities is transported to Tosco - San Francisco Area Refinery, located in Rodeo, California hWorm%lunnealcop ffin 101121!03