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Well Purging <br /> If the depth to groundwater was above the top of screens of the monitoring wells,then the <br /> wells were purged. Before sampling occurred, a polyvinyl chloride (PVC) bailer, <br /> centrifugal pump, low-flow submersible pump, or Teflon bailer was used to purge <br /> standing water in the casing and gravel pack from the monitoring well. Monitoring wells <br /> were purged according to the protocol presented in Figure C-l. In most monitoring <br /> wells, the amount of water purged before sampling was greater than or equal to three <br /> casing volumes. Some monitoring wells.were expected to be evacuated to dryness after <br /> removing fewer than three casing volumes. These low-yield monitoring wells were <br /> allowed to recharge for up to 24 hours. Samples were obtained as soon as the monitoring <br /> wells recharged to a level sufficient for sample collection. If insufficient water recharged <br /> after 24 hours,the monitoring well was recorded as dry for the sampling event. <br /> Field measurements of pH, specific conductance, and temperature were recorded in a <br /> waterproof field logbook. Field data sheets were reviewed for completeness by the <br /> sampling coordinator after the sampling event was completed. <br /> The pH, specific conductance, and temperature meter were calibrated each day before <br /> field activities were begun. The calibration was checked once each day to verify meter <br /> performance. Field meter calibrations were recorded on the water sample field data sheet. <br /> Well Sampling <br /> A Teflon bailer was the only equipment acceptable for well sampling. When samples for <br /> volatile organic analysis were being collected, the flow of groundwater from the bailer <br /> was regulated to minimize turbulence and aeration. Glass bottles of at least 40-milliliters <br /> volume and fitted with Teflon-lined septa were used in sampling for volatile organics. <br /> These bottles were filled completely to prevent air from remaining in the bottle. A <br /> positive meniscus formed when the bottle was completely full. A convex Teflon septum <br /> was placed over the positive meniscus to eliminate air. After the bottle was capped, it <br /> was inverted and tapped to verify that it contained no air bubbles. The sample containers <br /> for other parameters were filled, filtered as required, and capped. <br /> When required, dissolved concentrations of metals were determined using appropriate <br /> field filtration techniques. The sample was filtered by emptying the contents of the <br /> Teflon bailer into a pressure transfer vessel. A disposable 0.45-micron acrylic copolymer <br /> filter was threaded onto the transfer vessel at the discharge point, and the vessel was <br /> sealed. Pressure was applied to the vessel with a hand pump and the filtrate directed into <br /> the appropriate containers. Each filter was used once and discarded. <br /> Sample Preservation and Handling <br /> The following section specifies sample containers, preservation methods, and sample <br /> handling procedures. <br /> ff COAPOBOMfi <br /> SAC:\N:\Consulring\data\Shared\Projects\PJ8\809251.aa.doc-00\ta:l <br /> 809251 <br />