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Ouray Silver Mines Inc. <br /> Technical Revision 11 March 26, 2020 <br /> • Cadmium in sample PILOT2018 SRBCOMP was detected at 0.00105 mg/L; above <br /> the groundwater standard of 0.001 mg/L but below the stormwater standard of 0.0045 <br /> mg/L; <br /> • Copper in sample PILOT2018 SRBCOMP was detected at 0.0091 mg/L; above the <br /> groundwater standard of 0.009 mg/L but below the stormwater standard of 0.0285 <br /> mg/L; <br /> • Iron in PILOT2018 SRBCOMP was detected at 1.72 mg/L; above groundwater and <br /> stormwater standards of 1 mg/L; <br /> • Lead in PILOT2018 SRBCOMP leachate was detected at 0.202 mg/L; above the <br /> groundwater standard of 0.044 mg/L but below the stormwater standard of 0.213 <br /> mg/L; <br /> • Silver in PILOT2018 SRBCOMP was 0.0016 mg/L; above the groundwater standard <br /> of 0.001 mg/L but below the stormwater standard of 0.0138 mg/L; and <br /> • Zinc in PILOT2018 SRBCOMP was 0.239 mg/L; above the stormwater standard of <br /> 0.23 mg/L but below the groundwater standard of 0.74 mg/L. <br /> To remove the treatment media,the tanks will be cut up in place and the materials will be moved <br /> by loader for storage on the surface. Initially, the material will be placed adjacent to the topsoil <br /> pile, which is within the monitored disturbance boundary of the Mine(see Map 2). Once <br /> construction of the full-scale passive treatment system is complete, which is anticipated during <br /> the summer of 2020, the materials will be used in place of topsoil to reclaim the slopes of the <br /> ponds to encourage natural plant growth. If needed, these materials may also be included in the <br /> lined SRB pond approved by DRMS (TR 10). All areas considered for pilot passive treatment <br /> materials placement (Map F-la) are monitored with groundwater wells and within the site-wide <br /> stormwater collection system. <br /> Materials(totaling approximately 25 cubic yards) will be placed along the slopes of ponds after <br /> construction(Map F-la). A thin layer, 3-6 inches along the slopes will provide organic rich <br /> materials to facilitate natural seed growth. <br /> Materials placed into the sulfate reducing bioreactor would function as they did during the pilot <br /> test, as described in the Treatability Study (Appendix 1) and as permitted under the CDPS Permit <br /> CO-0000003 Modification 5 and, TR-10. <br /> The material placement will be monitored by groundwater wells and runoff from this area is <br /> captured in the water management system for discharge through monitored stormwater or <br /> industrial wastewater outfalls. <br /> Page 6 of 8 <br />