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SOP No. 22.0 Purging and Sampling Monitoring Well <br />7. Bail the well at a uniform rate, measuring water quality parameters after the <br />collection of each original casing volume. <br />8. Dispose of the contents of the bailer in an appropriate container for later disposal <br />in compliance with federal and state laws. <br />9. Attempt to remove a minimum of three well volumes before sampling. <br />a. If unable to remove 3 well volumes, purge until well is dry, or as nearly <br />dry as possible. <br />b. Measure the field parameters again as soon as enough water has returned <br />to measure. <br />c. Bail the well down again when it has recovered at least one half of the <br />original casing volume. <br />d. Re-measure the field parameters each time another full casing volume has <br />been removed, and just before sampling. <br />e. Bail a maximum of three full casing volumes in 4 hours. Do not bail more <br />than three casing volumes from a low or moderate yield well, as the time <br />required would be excessive. <br />f. If the well has produced only two full casing volumes at the end of 4 <br />hours, proceed to sample. <br />g. If the well has not produced two full casing volumes after 4 hours, bail <br />the well dry one more time. Return to sample in 4 more hours (total time <br />from first bailing until sampling equals 8 hours). <br />h. If the well has not recovered at all within 4 hours, do not sample. <br />12. After the minimum purge volume has been removed, review the geochemical <br />measurements to ensure the readings have stabilized. Readings should be <br />within 10% of the previous reading. If the geochemical parameters have not <br />stabilized, continue to purge the well until the monitoring parameters do not <br />vary more than 10 percent between two successive well volumes removed. <br />13. Collect the groundwater samples after purging is complete (see above). When <br />collecting samples, lower the bailer slowly to avoid agitating the water. <br />14. Once the sample has been taken, properly dispose the used string, gloves, and <br />paper towels. <br />7/17/07 Page 4 of 9 R Squared Inc.