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were selected for chemical analysis. PZ-01 was not sampled in the first quarter of 2024 and will thus require additional <br /> sampling in the second quarter of 2025 to obtain five (5)quarters baseline data. <br /> After completion of the five (5)quarters of baseline monitoring in the second quarter of 2025, sample collection <br /> frequency will switch two (2)times per year and the wells will be sampled in March and September of each year which <br /> corresponds to the currently observed low and high groundwater elevation periods. <br /> 5.1 Sample Collection Methods <br /> Samples will be collected starting in the upgradient well and progressing towards the downgradient well. PZ-20 <br /> will be sampled first followed by PZ-09, PZ-01 and then PZ-04. Samples will be collected on the same day. <br /> Depth to water will be determined using a water level indicator probe and volume of water inside the well will be <br /> calculated and recorded. <br /> The initial sampling will purge six (6)well volumes of water prior to sampling to remove residue left over from <br /> the drilling process. Subsequent sampling events will require three (3)volumes of water purged prior to <br /> sampling. Field parameters of pH, temperature, conductivity, and dissolved oxygen will be sampled before and <br /> after each volume of water inside the well is purged. The meter for sampling field parameters will be cleaned <br /> and calibrated prior to use. If field parameters vary more than 10%between purges, then purging should <br /> continue until six(6)volumes have been purged. The static volume of water in the well will be calculated using <br /> the following equation: <br /> V=r2h(0.163) <br /> Where <br /> V=static volume of water in well (in gallons) <br /> r= inner radius of well casing (in inches) <br /> h =length of water column (in feet)which is equal to the total well <br /> depth minus depth to water. <br /> 0.163= a constant conversion factor that compensates for the <br /> conversion of the casing radius from inches to feet for 2-inch diameter <br /> wells and the conversion of cubic feet to gallons, and pi (A). This <br /> factor would change for different diameter wells. <br /> Samples will be collected in a matter described by the laboratory and in the bottles they provide. The <br /> Groundwater will be retrieved using disposable polyethylene bailers and poured into a clean pitcher to be <br /> distributed to the appropriate sample bottle. Samples will be stored inside a cooler packed with ice and will be <br /> delivered to the laboratory within twenty-four(24)hours. <br /> A chain of custody form will be completed indicating the analysis to be performed on each sample and will <br /> accompany the samples to the lab. One duplicate sample will be collected per sampling event for quality <br /> assurance. The duplicate analysis will be included in the tabulated results presented to the Division. <br /> 5.2 Analytes To Be Sampled <br /> MMMA will sample the analytes listed in Appendix B of the"Groundwater Monitoring: Sampling and Analysis <br /> Plan Guidance" September 2023. The full list of analytes is shown in Appendix B. <br /> 5.3 Report <br /> The analytical results will be reviewed and a summary compiled comparing the results to the regulatory limits <br /> established by the Colorado Water Quality Control Commission (WQCC) and listed in Tables 1-4 of Regulation <br /> 41. MMMA will submit a Technical Revision to the Division containing the tabulated baseline results and an <br /> Monitoring and Analysis Plan—Monarch DENM Gravel Mine -4- March 2024 <br />