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Columbus Mine Portals <br /> Page 2 <br /> Description - Cont <br /> 4) Adequate ground cover over the potential site to resist the hydrostatic forces from the <br /> potential maximum head. <br /> If an acceptable location can be found, SGC will design and install two hydraulic seals. After <br /> sealing is complete, the seal will be contact grouted and the diversion pipes, if necessary for <br /> construction, grouted. The near surface fracture flows typically found will be diverted to avoid <br /> contact with waste material and the portal closed. See attached paper on hydraulic seals. <br /> Work Plan <br /> 1) Build catchments. <br /> 2) Open and evaluate adits for hydraulic seals. <br /> 3) Design and install hydraulic seals. <br /> 4) Grout seals and bypass pipes. <br /> 5) Portal closure. <br /> 6) Surface diversions and dump regrading. <br /> 7) Addition of pH neutralizing material, seeding and mulching. <br /> Analysis <br /> Diversion and isolation of the mine dumps(including pH stabilization)will isolate this material <br /> from direct contact with run on and intermittent flows and minimize infiltration from stormwater <br /> events. This will improve water quality of the Animas River at Animas Forks. <br /> The hydraulic seals proposed for the Columbus Adits will reduce the unsaturated zone by <br /> removing the drain. This will result in minimizing the oxygen available for reaction with the sulfide <br /> materials in the area. The hydrological conditions will be restored to an approximation of premining <br /> conditions and will improve the water quality in the area. <br /> Monitoring <br /> Monitoring points for this project will consist of upstream and downstream as well as flows <br /> from adits and dumps. Monitoring will start prior to remediation work and continue until two years <br /> after the project is completed. Monitoring will occur four times yearly, once in early summer and fall <br /> and will be submitted annually at the same time of SGC's Mined Land Reclamation submittal. A copy <br /> will also be sent to the Water Quality Control Division. All samples taken will be analyzed for <br /> dissolved and total recoverable metals for Pb, Cu, Zn, Cd, Mn and Fe. A field pH will be taken as <br /> well as field measurements for flow. <br />