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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 laboratory . 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 a MMC flexi-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 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 are not available , the laboratory is instructed to preserve the sample as appropriate . Duplicate samples are 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 4cC for 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 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 time 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 Tosco Marketing Company , the purge water and decontamination water generated during sampling activities is transported to Tosco - San Francisco Area Refinery , located in Rodeo , California . hlfomultouo-wp.hm-t/9B