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COLORADO LEGACY LAND <br /> $CHWARTZWALDER MINE <br /> the results of the transducer below the mine pool and therefore not accurately measuring the depth <br /> of the mine pool. <br /> • Actual groundwater inflow into the mine during the periods that active dewatering of the mine pool <br /> was not occurring did not raise the mine pool elevation above the regulatory limit. <br /> • The natural recovery rate allows for more than six months before the regulatory limit is approached, <br /> based on a starting mine pool elevation of approximately 345 ft below the Steve Level. <br /> • As shown on Figure E-4,water level measurements in bedrock wells MW-13, MW-15,and MW-18 at <br /> the Site demonstrate an inward gradient toward the mine pool and away from Ralston Creek. <br /> Chemical stabilization of the mine pool has been demonstrated to occur as a result of CLL's management <br /> approach and reclamation at the Site and has also been benefited by in-situ treatments that have occurred since <br /> 2013.The stabilization is most notable in evaluating the bulk water chemistry parameter TDS,which remains <br /> generally unchanged since 2012, except for the noted period of suspect data. Further, a decrease in uranium <br /> and molybdenum concentrations and the overall decrease in concentrations for most of the analytes is <br /> observed,as shown in Table E-3,for the last four consecutive years as compared to the concentrations in the <br /> pre-2017 samples. <br /> A summary of the WTP operations for the four consecutive years from 2018 through 2021 is provided in <br /> Table E-4.As shown,the mine pool has been consistently below the regulatory limit when only operating the <br /> WTP for approximately 50% of the time. The mean concentration of dissolved uranium prior to in-situ <br /> treatment(2000-2007) was 41.14 mg/L. (Source:Whetstone Associates.2007) compared to the post in-situ <br /> treatment mean annual concentration range of 12.19 to 19.90 mg/L. <br /> On the totality of evidence,the operating approach for the Schwartzwalder Mine that is being managed by CLL <br /> and is the basis for the financial assurance provided for the Site, shows that the mine pool is physically and <br /> chemically stable now, has been physically and chemically stable for the last 4 years, and with the future <br /> projections showing that operations of the Site can maintain the mine in a physically and chemically stable <br /> state for at least the next 20 years as is provided for in the financial assurance that CLL has posted. <br /> • <br /> AUGUST 2022 33 AMENDMENT 6 <br />