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COLORADO LEGACY LAND <br /> 12150 E.Briorwood Ave.,Suite#135,Centennial,CO 80112 <br /> T.(303)862-3928 m,1,e <br /> May 4,2021 <br /> MAY 102021 <br /> Ms.Amy Eschberger <br /> Colorado Division of Reclamation,Mining,and Safety DIVISION OF RECLAMATION <br /> Department of Natural Resources MINING MD SAFETY <br /> 1313 Sherman Street,Room 215 <br /> Denver,CO 80203 <br /> Subject: First Quarter 2021 Sampling Results, <br /> Schwartzwalder Mine,Golden Colorado, <br /> Mine Land Reclamation Permit No.M-1977-300. <br /> Dear Ms.Eschberger: <br /> The first quarter sampling event at the Schwartzwalder Mine was conducted by Ensero Solutions US,Inc. <br /> (Ensero)field staff on January 27 to January 29,2021.In addition to presenting sample data,CLL is including a <br /> cross-section schematic to illustrate the Schwartzwalder mine pool elevation with respect to the elevation of <br /> the Ralston Creek surface water sample locations. During the first quarter sampling event,all samples take of <br /> Ralston Creek within the permit boundary were below the 30 µg/L. As shown in the attached schematic,given <br /> that the elevations of surface water location ARH (SW-ARH)and FBRG(SW-FBRG)were above the elevation of <br /> the mine pool at the time of sampling,the concentrations of uranium in Ralston Creek outside of the permit <br /> boundary at SW-ARH and SW-FBRG and the downstream locations,SW-LLHG and SW-WEIR,are not tied to the <br /> mine pool.In addition,the elevated water level in Monitoring Well 15 CMW-15)from fourth quarter 2020 <br /> shows a groundwater divide exists between the mine pool and Ralston Creek. <br /> • Surface Water Data: There are thirteen quarterly surface water(SW)sampling locations.Figure 1 <br /> shows the location of each surface water sample locations along Ralston Creek.Table 2a summarizes <br /> surface water field parameters.Table 2b summarizes the analytical data results.The analytical <br /> laboratory data report and the chain of custody are attached to this report.A copy of the electronic <br /> data deliverable(EDD)excel file for these samples are included in this submittal. <br /> • Groundwater Data:There are thirteen quarterly groundwater monitoring well (MW) locations.Table <br /> 1 shows the monitoring well elevations.Figure 2 shows the location of each MW.Table 3a summarizes <br /> groundwater field parameters. Table 3b summarizes the analytical data results. The analytical <br /> laboratory data report and the chain of custody are attached to this report.A copy of the EDD excel file <br /> for these samples are included in this submittal. <br /> • Mine Pool Elevations:Table 4 summarizes the mine pool elevations for the quarter.Pumping of the <br /> mine pool has consistently maintained the mine pool elevation below the regulatory limit of 150 feet <br /> (ft)below the Steve Level even during months of no pumping.Maintaining the mine pool below the <br /> regulatory limit has established a hydraulic gradient away from Ralston Creek,preventing mine water <br /> from entering the creek in the permit area. <br /> If you have any questions regarding this letter,please do not hesitate to contact me. <br /> Sincerely, <br /> y w. <br /> PAGE 1 OF 15 <br />