Laserfiche WebLink
Title: Sampling and Analysis Plan for Environmental Control Number: Revision Date: Page 8 of 23 <br /> Groundwater Monitoring PUE.EN.D.026.03 10/18/2019 <br /> following the removal of the third wetted casing volume if field water quality parameters show <br /> relative stability (within approximately 10%) and two or more parameters show no significant <br /> trend of increasing or decreasing value. If the meter readings for pH, temperature and <br /> conductivity do not stabilize, field personnel need only remove five casing volumes before <br /> taking a groundwater sample. <br /> Purging of each well will be accomplished with either a dedicated and disposable bailer or a <br /> dedicated in-situ pump system. During the purging process,temperature,pH,and conductivity <br /> are measured and entered on the field sampling form after each casing volume is removed. At <br /> all times,purging and sampling equipment will not be allowed to come into contact within the <br /> ground or other potentially contaminated surface. <br /> Water samples to be analyzed for dissolved metals will be collected in a dedicated, disposable <br /> plastic container (e.g., emptied distilled water jug) for filtration in the field. Samples will be <br /> filtered through a 0.45-micron disposable filter cartridge directly into laboratory-prepared <br /> containers, using dedicated and disposable silicon tubing. Sample containers provided by the <br /> lab typically contain a nitric acid preservative. If this is not the case, preservatives will be <br /> added immediately after the samples are filtered. <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. <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 <br /> best 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 />