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Section No 6 <br /> Revision No 0 <br /> Date September 5, 1991 <br /> Page 22 of 55 <br /> 6 4 6 Purging <br /> Purging will be conducted immediately before sampling The volume of <br /> well water to be purged from each well or screened well interval sampled will <br /> be determined as follows: <br /> ■ At least three times the volume of water in the well casing will be <br /> removed <br /> ■ Readings of temperature, pH, and specific conductivity will be taken <br /> for at least every casing volume removed Purging will not be <br /> terminated until values for each of these parameters have stabilized <br /> - to within ten percent - - - <br /> For purging wells, the following procedures apply <br /> 1 Measure and record water levels before pumping <br /> 2 Measure and record the depth to the bottom of the well 0 <br /> i3 Follow the pump installation and operating procedures <br /> 4 —Use-the-above—guidelines-to-calculate--the--minimum-volume-of-water-to— - <br /> be purged form-the-well to be sampled <br /> 5 Record the time that purging is started. <br /> 6 The pumping discharge rate should be carefully monitored and <br /> recorded periodically so that the volume of water purged can be <br /> accurately calculated <br /> 7 Measure and record temperature, pH, and specific conductivity <br /> parameters at intervals which correspond to no more than one casing <br /> volume Continue to purge until the readings stabilize to +10 <br /> percent and the minimum water volume calculated has been removed <br /> ' Other observable water parameters should be noted and recorded, such <br /> as water color, turbidity, clarity, and odors observed <br /> 8 Measure and record water level in the well periodically during <br /> purging Lower the pumping rate if excessive drawdown of water <br /> level is observed <br /> 9 Record the time that purging is stopped. <br /> 10 Record water levels after purging 0 <br /> 6-22 <br />