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Stiles Mining Resource <br /> Groundwater Monitoring and Mitigation Plan <br /> November 2022 <br /> Page 7 <br /> 3.7.4 Potential Additional Assessment and Corrective Action Measures <br /> ASCI will work with DRMS and down-gradient adjacent well owners within 600-feet to address <br /> the on-going impacts to groundwater quality, as appropriate. The following activities may <br /> potentially be implemented: <br /> ■ Discuss options available with down-gradient adjacent well owner(s)within 600-feet to <br /> reach a mutually agreed upon solution to replace the water sourced from the impacted <br /> well with an appropriate alternate water source for equivalent use(e.g., install new well, <br /> water tap connection, etc.). <br /> ■ Installation of new monitoring well(s)to characterize the nature and extent of <br /> groundwater quality impact(s). <br /> 4.0 GROUNDWATER QUANTITY MONITORING <br /> ASCI will pump groundwater to facilitate dry mining at the Site which will affect groundwater <br /> levels within the alluvial aquifer GWBU. As a result,ASCI will monitor groundwater levels at the <br /> HBP property boundaries to observe any affects from pumping and to identify potential adverse <br /> off-site impacts to nearby wells completed within the alluvial aquifer. According to the Colorado <br /> Division of Water Resources (DWR) Colorado's Decision Support System (CDSS) Well Permit <br /> Viewer, the transmissivity of water flow through the alluvial aquifer in this area generally ranges <br /> between 80,000 to 100,000 gallons per day per foot (gpd/ft). All nearby alluvial aquifer wells <br /> identified are anticipated to be hydraulically up-gradient or cross-gradient relative to any area <br /> being mined at the Site. Only two (2)wells are located on an adjacent property within 600 feet of <br /> the permit boundary(Well Permit No. 55498-MH and 55499-MH). The location of these wells are <br /> shown on Figure 2. <br /> 4.1 MONITORING WELL NETWORK <br /> A monitoring well network of seven (7) wells will be used to observe groundwater levels in the <br /> alluvial aquifer GWBU at the HBP property boundaries. The network will consist of the six (6) <br /> groundwater quality monitoring wells (MW-1 through MW-6) and a seventh well (MW-7) <br /> completed along the eastern HBP boundary. The location of these wells are shown on Figure 2. <br /> 4.2 GROUNDWATER MEASUREMENT FREQUENCY AND SCHEDULE <br /> Beginning in March 2021, ASCI will collect monthly groundwater elevation readings from <br /> monitoring wells MW-1 through MW-7 to establish baseline groundwater level conditions at the <br /> Site prior to commencing mining operations (Pre-Operational Groundwater Level Monitoring). <br /> ASCI will continue to collect monthly groundwater elevation readings (i.e., current groundwater <br /> level monitoring schedule)for a minimum of four(4)consecutive quarters after mining operations <br /> begin(Post-Operational Groundwater Level Monitoring). Any change to the current groundwater <br /> level monitoring schedule (i.e., reduction in measurement frequency) will be submitted to DRMS <br /> via Technical Revision for approval prior to implementing. <br />