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• B. 4. PNEUMATIC DISPLACEMENT SAMPLER <br />Pneumatic displacement sampler systems have been installed in nonflowing <br />bedrock wells. The system includes a pneumatic displacement sampler, 3/4 <br />inch diameter airline for well purging, and a 1!4 inch diameter airline <br />for water level measurement. One to three casing volumes of water is <br />removed from each well using an air compressor. For the sampling systems <br />presently installed, the wells must be purged with the compressor for a <br />minimum of 10 minutes. All the airlines terminate above the sampler so <br />that the water sample collected has not been contaminated with air. The <br />pneumatic sampler is purged with nitrogen to collect the water sample. <br />This procedure for collecting ground water samples is as follows: <br />• <br />• <br />1. Measure the water level in the well before beginning the <br />sampling procedure. <br />2. Connect the compressor to the 3/4 inch diameter airline. <br />3. Start the compressor. Purge the well for at least 10 minutes. <br />Begin clocking the ten minutes when water first discharges from <br />it from the well. <br />work best when the water <br />due to the low recovery <br />be collected B to 24 hours <br />in the well, connect the <br />inch diameter tubing). <br />taking airline water level <br />8. Purge line until gas discharges and use fluid to rinse field <br />parameter measurement equipment and bottles. Pour any remaining <br />water to waste. <br />9. Shut off pressure until gas stops discharging from line. <br />10. Purge line again. <br />11. Collect additional fluid and take field measurements. <br />12. Collect additional fluid as indicated in the previous steps <br />until the laboratory sample bottles are filled. <br />13. Disconnect nitrogen bottle from line. <br />14. Sample bottles must be cooled with ice immediately upon <br />collection and delivered to the laboratory as soon as possible. <br />the well. <br />Turn off the compressor and disconnect <br />The pneumatic displacement samplers <br />level is high in the well; therefore <br />rate of the wells, the sample should <br />after the wells are purged. <br />After the water level has recovered <br />nitrogen tank to the inlet tubing (3/8 <br />Pressurize line (see instructions for <br />measurements). <br />B-3 <br />