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COLORADO LEGACY LAND <br /> $CHWARTZWALDER MINE <br /> E.5.4. Water Treatment Plant Operating Strategy <br /> CLL is planning to operate the WTP seasonally for approximately six months or less to manage the mine pool. <br /> As described above,shutting the WTP down for at least six months each year is based on empirical data with a <br /> conservative factor included. However, as more data are collected and the mine pool level maximized below <br /> the regulatory limit,the shut down period may be extended beyond six months. Regardless of the shut down <br /> period, the mine pool level will be monitored to ensure the regulatory limit is not exceeded. The months of <br /> operating the WTP are anticipated to be during the time of year in which access to the Schwartzwalder Mine is <br /> generally not hampered by weather. During operations, the 60-hp pump shall be used to dewater the mine <br /> workings to approximately 400 ft below the Steve level.The pump will be shut down during those months the <br /> WTP is not operating and as described above,the last three years of operating this way has demonstrated that <br /> the mine pool level has remained stable below the regulatory limit. <br /> The WTP operating strategy is considered in conjunction with in-situ treatment of the mine pool. During the <br /> period in which the WTP is shut down,in-situ treatment of the mine pool may at times be conducted,as needed, <br /> to maintain chemical stabilization.The criteria for in-situ treatment of the mine pool shall consist of the Mann- <br /> Kendall trend test to evaluate statically significant trends in the uranium concentrations. <br /> EA WATER QUALITY MONITORING PLAN <br /> This Exhibit has not changed from the 2021 Mine Plan Amendment 5. <br /> All of the wells/sumps in CLL's water quality monitoring network are installed in unconfined aquifers.These <br /> wells/sumps shall be abandoned in accordance with Rule 16,Standards for Plugging,Sealing and Abandoning <br /> Wells and Boreholes of the Colorado Code of Regulations which states: <br /> "Abandonment of Wells or Boreholes in Type II (unconfined bedrock aquifers) and Type III Aquifers <br /> (unconsolidated aquifers) - Wells completed into unconfined bedrock aquifers and unconsolidated <br /> aquifers must be plugged,sealed,and abandoned by filling the well to the static water level with clean <br /> sand or clean gravel.Between the static water level and the ground surface,the borehole must be filled <br /> with clean native clays,cement,drill cuttings,or high solid bentonite grout to the ground surface.The <br /> uppermost five (5) feet of casing must be filled with grout or a permanent watertight cover must be <br /> installed at the top of the casing. If casing is removed, the hole must be filled as described above to <br /> within five(5) feet of the ground surface."4 <br /> Specific means and methods shall be determined by the well abandonment subcontractor,but CLL expects that <br /> each well be filled with sand from the bottom of the well to 5-feet above the screen, and then grounded with <br /> bentonite to ground surface. Similarly,CLL expects the inverted-culvert housing around each sump and lid to <br /> be removed and taken offsite for disposal or scrap metal recycling. The sump void space will be backfilled with <br /> 4 Rules and Regulations for Water Well Construction,Pump Installation Cistern Installation,and Monitoring <br /> and Observation Hole/Well Construction,Code of Colorado Regulations,division of Water Resources, <br /> 2 CCR 402-2. <br /> AUGUST 2022 35 AMENDMENT 6 <br />