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Diversion of the Swan River will limit the amount of surface water that may flow past the <br /> IXURoyal Tiger site. The diversion will isolate the adit discharges from the main <br /> surface-water flow system. This will reduce the potential metals load carried away from <br /> the site and reduce potential erosional impacts on the existing and created wetlands <br /> during spring snowmelt and runoff. <br /> 9.2.4 Improve Tailings Cover <br /> CDPHE (2002)identified deficiencies in the cover installed over the fine-grained tailings <br /> below the former mill area. Fine-grained tailings with concentrations exceeding the RMC <br /> benchmarks for wildlife/livestock and recreational uses were observed along the edges <br /> of the cover in some areas. The vegetative cover was also found to be sparse and <br /> consisting of a monoculture of an exotic species. <br /> The existing cover will be repaired and improved to eliminate potential human or wildlife <br /> contact with fine-grained tailings in this area. The vegetative cover will also be improved <br /> to limit the spread of exotic species and replace them with appropriate native plants. <br /> The toe of the existing cover adjacent to the ditch along the south side of the valley will <br /> be regraded to approximately a 2 to 1 slope. The grading will be integrated with the <br /> constructed wetlands to limit erosion from the cover and promote appropriate surface <br /> drainage into the wetlands area. <br /> The surface of the existing cover will be improved by the addition of topsoil from either <br /> an on-site borrow area or off-site sources. Nutrients will be added if necessary to ensure <br /> an adequate substrate for plant growth. The cover will then be re-vegetated with an <br /> appropriate mix of native species. We anticipate that the cover area will be hand- <br /> seeded with both Canada reedgrass and tufted hairgrass(Deschampsia cespitosa). <br /> These species are appropriate to the location and elevation of the IXURoyal Tiger site. <br /> The re-vegetated cover area will then be covered by a weed-free mulch for protection <br /> and promotion of initial growth. <br /> Improving the existing cover over the fine-grained tailings below the former mill area will <br /> reduce the potential for erosion of the cap; reduce the potential for saturation of capped <br /> materials by surface water; and reduce percolation of precipitation into the underlying <br /> tailings.The combined benefit will be to reduce the potential metals loading into the <br /> aquatic environment and eliminate potential direct contact by wildlife or humans with <br /> tailings materials containing elevated metals concentrations. <br /> 9.2.5 Cover Stream-side Tailings <br /> The stream-side tailings consist of discrete areas of fine-grained tailings along the south <br /> side of the Swan River valley downgradient of the site. The majority of these tailings <br /> occur in relatively flat piles on either side of the ditch on the south side of the valley, but <br /> some of the piles have steeper slopes where they are deposited adjacent to the hills <br /> forming the south boundary of the alluvial valley. The stream-side tailings can be <br /> visually identified by a bright-yellow color due to the weathering of iron-bearing minerals <br /> in the tailings material. <br /> CDPHE (2002) identified approximately 4,669 cu. yd.of stream-side tailings with a total <br /> surface area of about 2,960 square yards. Summit County personnel identified <br /> additional piles of intermixed stream-side tailings and dredge tailings along the southern <br /> edge of an area of dredge tailings that had been excavated for gravel. The additional <br /> intermixed piles are discrete piles that can be visually identified by the occurrence of a <br /> yellow, fine-grained matrix. While the larger dasts are not expected to create any <br /> IXURoyal Tiger vCUP Application Page 25 of 33 <br />