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PROTOCOLS FOR QUARTERLY GROUNDWATER MONITORING <br />! <br /> GROUNDWATER GAUGING <br />! Wells are opened prior to gauging to allow the groundwater level in the wells to equilibrate with <br /> atmospheric pressure The depth to groundwater and depth to hgwd-phase hydrocarbons,zfpresent, <br /> are then measured to the nearest 0 01 feet using an electronic water level meter or optical interface <br />! probe The measurements are made from a permanent reference point at the top of the well casing <br /> If less than 1 foot of water is measured in a well, the water is bailed from the well and, if the well <br /> does not recover,the well is considered"functionally dry" Wells with a sheen or measurable liquid- <br /> phase hydrocarbons are generally not purged or sampled <br /> WELL PURGING <br /> After the wells are gauged, each well is purged of approximately 3 well casing volumes of water to <br /> provide representative groundwater samples for analysis Field parameters of pH,temperature, and <br />! electrical conductance are measured during purging to ensure that these parameters have stabilized <br /> before groundwater in a well is sampled Groundwater in each well is purged using an inertial pump <br /> (WaTerra), an electric submersible pump, or a bailer After the well is purged, the water level is <br /> checked to ensure that the well has recharged to at least 80 percent of its original water level <br /> GROUNDWATER SAMPLING <br /> After purging, groundwater in each well is sampled using dedicated tubing and an inertial pump <br /> (WaTerra) or a factory-cleaned disposable bailer. Samples from extraction wells are typically <br /> collected from sample ports associated with the groundwater remediation system Samples collected <br /> for volatile organic analysis are placed in Teflon septum-sealed 40-milhhter glass vials Samples <br /> collected for diesel analysis are placed in 1-liter amber glass bottles Each sample bottle is labeled <br /> with the site name,well number,date,sampler's imtals,and preservative The samples are placed in <br /> a cooler with ice for delivery to a state-certified laboratory The information for each sample is <br /> entered on a chain-of custody form pnor to transport to the laboratory <br /> G\Projects\Exx=Mobg\MasteTNExxonMobtl QMR ternplates\QMR protocols-purge-waters doc <br />