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London Mine Portals <br />Page 2 <br />Description - Cont <br />2) Adequate rock compressive strength for structural stability. <br />3) A length of the tunnel with minimal faulting or other geologic features that could serve <br />as a leakage pathway. <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 hydraulic seals. After <br />sealing is complete, the seals 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 Portals. <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 portal flows and minimize infiltration from stormwater events. <br />These Best Management Practices may improve Burrows Creek as well as the headwaters of the <br />Animas River. <br />The hydraulic seals proposed for the London Mine 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 should 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 />