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1 <br /> 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 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 and, if the well does not recover, <br /> the well is considered "dry " Wells with a sheen or measurable liquid-phase hydrocarbons are <br /> 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 parameters are considered stable when two <br /> consecutive readings indicate no greater than a 10 percent change from the previous reading for <br /> temperature and electrical conductance and no greater than a 0 1 pH units change from the previous <br />' reading for pH Groundwater in each well is purged using an inertial pump, an electric submersible <br /> pump, or a bailer After the well is purged, the water level is checked to ensure that the well has <br /> recharged to at least 80 percent of its original water level <br />' GROUNDWATER SAMPLING <br /> fAfter purging, groundwater in each well is sampled using dedicated tubing and an inertial pump <br /> (WaTerra) Samples from extraction wells are typically collected from sample ports associated with <br />' the groundwater remediation system Samples collected for volatile organic analysis are placed in <br /> Teflon septum-sealed 40-milliliter glass vials Samples collected for diesel analysis are placed in <br /> 1-liter amber glass bottles Each sample bottle is labeled with the site name, well number, date, <br />' sampler's initials, and preservative The samples are placed in a cooler with ice for delivery to a <br /> state-certified laboratory The information for each sample is entered on a chain-of-custody form <br /> prior to transport to the laboratory <br /> I <br /> I <br />' 0 TmiectsTxxortMobllWaster\ExxonMobil QMR templates\QMR protocols purge-watena doc <br />