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Beyond the documentation provided by profile comparisons, Trapper Mine hras spared no effort and <br />expense in constroding reestablished drainages that effectively control erosion and downstream <br />sediment deposftion. A variety of sediment control materials and methods and sediment reducing <br />measures have been implemented on reestablished drainages. <br />Rock check structures are used to dissipate the energy of flowing water within drainage channels. <br />Debris and sediment tend to be deposited and trapped upstream of structures. This in tum permits <br />establishment of vegetation behind structures which further stabilizes the channels. In addition, filler <br />fabric is installed and used to line rock check structure core trenches, thus providing additional <br />structural support and reduces the potential of downstream headcutting to move upstream. <br />Different treatment combinations of wver crops, mulch, synthetic fabrics and fibers, and brush <br />matting are used effedively in drainageways to reduce erosion while providing seasonal protection <br />and soil improvement. Those measures provide protection from wind and water erosion during <br />vegetation establishment periods when permanent vegetation is inadequate to provitle proper cover. <br />Subsequent establishment of permanent vegetation in reconstructed drainages insures future channel <br />stabildy. <br />This combination of appropriate conservation measures coupled with an effective drainage repair <br />program insures successful establishment of reconstructed drainage channeLr at Trapper Mine. <br />7.3 Drainage Control Documentation <br />All drainage control structures at Trapper Mine have been built according to ~ihe approved permit plan <br />and are functioning as designed. Approved sedimentation pond designs, incuding hydrologic <br />modeling backup, are routinely provided to DMG and are located in Appendix Q of the pemtil <br />document. Appendix Q also provides other drainage control documentation, including Professional <br />Engineer dam construction certifications and diversion ditch designs. <br />In addition to design information, documentation that Trapper Mine dreina!3e control structures are <br />functioning in accordance with the approved permR plan is provided by r:ontinuous surtace water <br />monitoring. The 'Annual Hydrologic Report" section of Trapper's annual reports contains a vast <br />amount of surtace water monitoring data that shows that Trapper is consistently in compliance with all <br />NPDES effluent discharge requirements. <br /> <br />1-2 <br /> <br />