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PROTOCOLS FOR QUARTERLY GROUNDWATER MONITORING <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 liquid-phase hydrocarbons,if present, <br /> are then measured to the nearest 0 01 feet using an electronic water Ievel 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 <br /> liquid-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-milliliter 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 initials, and preservative The samples are placed <br /> in 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 prior to transport to the laboratory <br /> r <br /> • <br />' G 1Projects\ExxonMobtl\Master\ExxonMobil QMR templates\QMR protocols-purge waterra doc <br />