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Title: Sampling and Analysis Plan for Environmental Control Number: Revision Date: page 8 of 30 <br /> Groundwater Monitoring I PUE.EN.D.026.04 2/19/2020 <br /> case of pre-preserved(pre-acidified)bottle utilization,care must be taken at the time of sample <br /> collection to not overflow the bottle which will flush some if not all ofthe acid from the sample, <br /> leaving said sample less than adequately preserved. If a bottle is overflowed, the bottle shall <br /> be discarded and an appropriate replacement pre-preserved sample bottle will be substituted <br /> from spare bottle set inventory,kept on hand for such occurrences. <br /> The method of sample collection can vary according to how much water a well produces and <br /> if a representative water sample can be collected. The following methods for bailer purging <br /> and sampling are adapted from Colorado Water Quality Control Division guidance (CDPHE <br /> WQCD, undated). Some slight modifications are made so that only produced water (not <br /> stagnant purge water) is submitted for laboratory analysis. In order to collect what is believed <br /> to be the most representative water sample, the time between purging and sampling low <br /> yielding wells may be adjusted given the behavior of a given well and until the response of a <br /> given well is observed over time. If dedicated pump systems are installed in any of the <br /> monitoring wells at a future date, purging and sampling will be performed using <br /> manufacturer's and EPA-approved guidance. The installation of such system(s) in any of the <br /> current or future groundwater monitoring wells shall require submittal and Division approval <br /> of a minor revision(MR)to the mine permit. <br /> 3.4.1 Method A for Groundwater Sample Collection <br /> This method is to be utilized for those wells that produce a sufficient volume of water and have <br /> a rapid recovery rate. <br /> • Purge the well water into a clean,dedicated collection container(e.g.,emptied distilled <br /> water jug)to measure and record temperature,pH,and conductivity. Continue purging <br /> until the stagnant water in the casing has been replaced by formation water.This is best <br /> determined by logging the readings for temperature, pH, and conductivity. After <br /> approximately three casing volumes have been removed from the well and once the <br /> most recent reading is within 10%of the previous two readings for each individual field <br /> parameter,a groundwater sample will be taken. If the field parameters do not stabilize, <br /> a minimum of five casing volumes shall be removed from the well prior to taking a <br /> groundwater sample. <br /> • If a bailer is used to purge the well, the bailer is to be lowered into the well to what <br /> hereinafter is referred to as the"sample depth". "Sample depth"is determined by <br /> lowering the bailer to the bottom of the well. Once the bailer is gently resting on the <br /> bottom,the field person is to mark this location on the cable. The mark is to be placed <br /> directly across from the measuring point while the cable is held taut. Raise the bailer <br /> one-foot above the bottom of the well. Mark the cable or place adhesive tape on the <br /> cable to indicate the sample depth for future reference.Taking a purge water sample at <br /> this elevation should avoid undue amounts of sediments in the sample and prevent <br /> sediment interfering with closure of the bailer valve. Prior to extracting water for field <br /> measurement,the well should be purged by bailing from the bottom of the well. Take <br /> "throw-away" samples from the sample depth to determine temperature, pH and <br /> conductivity after each casing volume and purge as described above. <br />