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�Iw % r r ,t f ` w h r%TF 11 KE "M� i SIERRA STANDARD OPERATING PROCEDURE GROUND WATER SAMPLING The following describes sampling procedures used by SES field personnel to collect and handic ground water samples. 13efore samples are coliected.careful consideration Is given to the type of analysis to be performed so that precautions are taken to prevent loss of volatile components or contamination of the sample,and to preserve the sample for subsequent analysis. Welts will be sampled no less than 24 hours after well development. Collection methods specific to ground water sampling are presented below. Prior to saunpling,each well E a ctreeiced for the presence of free-phase hydrocarbons using an MMC flexi-dip interface probe. Product thickness (measured to lire nearest 0.01 ft) is noted on the sampling form. Watcr level measurements are also matte using either a water level meter or the interface probe. "I'he water level measurements are also noted on the sampling form. urnes of water Prior to sampling, each well is purged of a mininr� 01 four vlp 1-[land elect icat using a steam-cleaned PVC bailer, or a pre-eleaned p i ' Temperature, conduclivtly are measured at least three times during purging, Purging is continued unlit these parameters have stabilived(t.e.,changes in temperature,pH or conductivity do not exceed+0.5"F. 0.1 or 5%, respectively). The purge water is stored temporarily on-site in 55-gallon Department of'rransportation- tic results. 'rhe drums are labeled with the date,contents,the SES approveddrums Pauling analy field personnel initials and SES phone number. Ground water sarnples are collected from the wells with steam-cleaned"teflon bailers. The water samples are decanted into the appropriate container far the analysis to be performed. Pre- preserved sample containers may be used or the analytic laboratory may add preservative to the froin each as a sample upon arrival. Duplicate sa1'n)les-are les are labeled to Includecthe project en mbermsln pie ID, to provide c]ua][ty control. The sa p date,preservative,and lire field person's initials. "the samples are placed in polyethylene bags and in an ice chest(maintained at A'C with blue Ice or ice)for transport under chair.-of-custody to the laboratory,