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<br /> <br /> <br />B.9 PNEUMATIC DISPLACEMENT SAMPLER <br />Pneumatic displacement sampler systems have been installed in <br />nonflowing bedrock wells. The system includes a pneumatic <br />displacement sampler with 1/9 inch air lines and a second 1/4 inch <br />diameter air line for well purging, and water level measurement. <br />The second air line terminates above the sampler. One to three <br />casing volumes of water is removed from each well using compressed <br />nitrogen through this second air line. The pneumatic sampler is <br />purged with nitrogen to collect the water sample. This procedure <br />for collecting ground water samples is as follows: <br />1. Measure the water level in the well before beginning the <br />sampling procedure. <br />2. Connect the nitrogen to the 1/4 inch diameter air line <br />that goes down center of well. <br />3. Open metering valve to about 150 psi or level necessary <br />to blow water out of well. Purge well until very little <br />water continues to discharge; then shut off nitrogen. <br />Purge the well at least three times waiting five minutes <br />between. <br />9. Turn off the nitrogen and disconnect it from the well. <br />5. The pneumatic displacement samplers work best when the <br />water level is high in the well; therefore, due to the <br />low recovery rate of the wells, the sample should be <br />collected 8 to 29 hours after the wells are purged. <br />6. After the water Ieve1 has recovered in the well, connect <br />the nitrogen tank to the inlet tubing (1/9 inch diameter <br />tubing goes down side of well). <br />7. Pressurize line (see instructions for taking air line <br />water level measurements). <br />8. Purge line until gas discharges and use fluid to rinse <br />field parameter measurement equipment and bottles. Pour <br />any remaining 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 <br />steps until 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 <br />possible. <br />B-3 Revised 1/9/93 <br />