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Plastic bottles and caps used in sampling for metals were soaked <br /> overnight in a 1 percent nitric acid solution. The bottles and caps were <br /> then triple rinsed with deionized water, and air dried before being used at <br /> the site. All plastic bottles and caps are constructed of linear polyethylene <br /> or polypropylene. Plastic bottles and caps were used only once and dis- <br /> carded after analysis was complete. <br /> ' Plastic bottles and caps used in sampling for general water-quality param- <br /> eters are not routinely washed. They are used only once and discarded <br /> after analysis is complete. <br /> Before the sampling event was started, equipment that was placed in the <br /> ' well or had come in contact with ground water was disassembled and <br /> cleaned thoroughly with detergent water, and then rinsed with steaming <br /> deionized water. Any parts that may have absorbed contaminants, such as <br /> plastic pump valves, bladders, etc., were cleaned as described above, or <br /> replaced. The inside surfaces of the positive displacement (bladder) pump <br /> (when used) tubing were cleaned by heating the tubing overnight at 120°C <br /> with a low-flow, inert air source. <br /> Once the bladder pump was cleaned and reassembled, a pump blank was <br /> obtained by pumping organic-free water through the bladder pump <br /> assembly. The pump effluent was sampled and analyzed by EPA <br /> Method 601. <br /> During field sampling, equipment surfaces that were placed into a well or <br /> that had contacted ground water were rinsed with steaming deionized <br /> water before the next well was purged or sampled, or both. <br /> Water-level and Total Well-depth Measurements <br /> Immediately before a monitoring well was purged, the water level and total <br /> well depth were measured using an electric sounder as described in the <br /> previous section entitled "Ground-water Elevation Survey." The electric <br /> sounder was decontaminated by being rinsed with deionized water after <br /> each use. <br /> j <br /> Well Purging <br /> Before sampling, standing water in the casing and gravel pack was purged <br /> from the monitoring well using a dedicated Well Wizard R bladder pump, <br /> pneumatic displacement pump, or Teflong bailer. Monitoring wells were <br /> pj9\939\9390111 c A-3 Rev. 0 September 9, 1992 <br />