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Attachment LK <br /> Page LK-4 <br /> Permit No. CO-0044768 <br /> Mine Waste Remediation <br /> The waste dumps will be moved and isolated from portal flows,intermittent stream flows and the pond. SGC <br /> will move and consolidate the dumps and adjust their pH to near neutral, by addition of lime, limestone or another <br /> acceptable product,for stabilization.The measured estimate of waste is 20,000 cubic yards. <br /> Preferably an isolation site can be found onsite. As an alternative, the dumps will be relocated to SGC's <br /> Tailings Pond #4. Prior to consolidation either onsite or offsite,the pH will be adjusted to near neutral. Once removal <br /> and consolidation is completed,the material will be capped with 14-16"of soil,provided that amount of soil is available, <br /> and planted in order to prevent direct contact with water. <br /> Surface disturbances will be pH adjusted with the use of limestone addition and planted SGC will apply for <br /> a 404 permit from the Army Corp.of Engineers for the work in the stream. <br /> Removal of buildings will be required on the South(Koehler)dump. This will require working with the San <br /> Juan County Historical Society. Planned activities would include historical recordation prior to removal. It is intended <br /> to leave all other structures intact including the buildings associated with the Longfellow Shag <br /> Mine Drainage Treatment Desimn <br /> Improvement in quality in the flows from the edits, natural seeps and the stormwater runoff poses a difficult <br /> problem due to the combination of low pH and high metals oontenL At this time it appears that the best solution is a <br /> passive bio treatment system.SGC will collect and sample waters from the underground sources to be treated. The water <br /> will be bench tested to provide data that will be used in the design of a passive bio treatment system to increase pH and <br /> reduce base metal concentrations. See attached paper on the passive bio treatment system. While SGC has agreed to <br /> complete this testing and project design,installation of an adit flow treatment project is not part of this Mime Remediation <br /> Work Plan or SGC's agreement to do mitigation projects. <br /> F <br /> Passive bio treatment Design Criteria <br /> Bench scale test results will provide design parameters that will utilize the space occupied by the current pond. <br /> The design will focus on establishing the longest practicable life for the installation. • <br /> During the design stage SGC will collect additional background information monthly, when the site is <br /> accessible. Information collected will include flow,pH, temperature,dissolved metals and hardness. Dissolved metals <br /> will be limited to Zn,Fe,Al,Mn,Cd,and Cu.A field pH will be taken as well as flow measurements during sampling. <br /> These and any other results from parameters monitored for design of the system will be included in the design report <br /> given to WQCD. <br /> Part of the design will include a monitoring program that can be used to determine metals reduction. The <br /> following will be considered in the design of the passive bio treatment system: <br /> (1) Volume of water to be treated. High and low flow characteristics. <br /> (2) Water temperature,pH and hardness. <br /> (3) Metal loadings and precipitation characteristics. <br /> (4) Retention time for passive system to react and deposit metals. <br /> (5) Life of passive treatment cell. <br /> (6) A target removal of seventy percent dissolved metals reduction from the project site <br /> (7) Conceptual plan for replacement of the passive bio treatment mass. <br />