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1 r <br /> rr <br /> SIERRA <br /> SES STANDARD OPERATING PROCEDURE <br /> GROUND WATER SAMPLING <br /> The following describes sampling procedures used by SES field personnel to collect and <br /> handle ground water samples Before samples are collected, careful consideration is given to the <br /> type of analysis to be performed so that precautions are taken to prevent loss of volatile <br /> i <br /> components or contamination of the sample, and to preserve the sample for subsequent analysis <br /> Wells will be sampled no less than 24 hours after well development Collection methods specific <br /> to ground water sampling are presented below <br /> Prior to sampling, each well is checked for the presence of free-phase hydrocarbons using <br /> an MMC flexi-dip interface probe Product thickness (measured to the nearest 0 01 foot) is noted <br /> on the sampling form Water level measurements are also made using either a water level meter <br /> or the interface probe The water level measurements are also noted on the sampling form <br /> Prior to sampling, each well is purged of a minimum of four well casing volumes of water <br /> using a steani-cleaned PVC bailer or a pre-cleaned pump Temperature, pH and electrical <br /> conductivity are measured at least three times during purging Purging is continued until these <br /> parameters have stabilised (i e changes in temperature, pH or conductivity do not exceed±O 5'F <br /> 0 1 or 5%, respectively) <br /> The purge water is stored temporarily on-site in 55-gallon Department of Transportation- <br /> approved drums pending analytic results The drums are labeled with the date, contents the SES <br /> field personnel initials and SES phone number <br /> Groundwater samples are collected from the wells with steam-cleaned Teflon bailers The <br /> water samples are decanted into the appropriate container for the analysis to be performed Pre- <br /> preserved sample containers may be used or the analytic laboratory may add preservative to the <br /> sample upon arrival Duplicate samples are collected from each well as a back-up sample and/or <br /> to provide quality control The samples are labeled to include the project number, sample ID, <br /> date,preservative, and the field person's initials The samples are placed in polyethylene bags and <br /> in an ice chest (maintained at 4°C with blue ice or ice) for transport under chain-of-custody to the <br /> laboratory <br />