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Sediment created from stormwater flows is the most likely pollutant <br />associated with the mine. Sediment can be produced from uncontrolled <br />stormwater eroding scoured/exposed working surfaces such as the access road <br />and pad. However, due to the presence of existing management practices <br />there is little to no evidence of any sediment release to off-areas. There is one <br />erosion channel that has been created as a result of the access road acting as a <br />conduit for stormwater. However, as stated in the introduction to this Section, <br />we propose to add a series of additional management features to control this <br />issue. It appears that existing management practices such as the revegetated <br />perimeter berms, are holding sediment in place. In addition, the natural <br />setting (porous slope, low snow accumulation) lends to controlling the amount <br />of stormwater potential. These combined attributes appear to be controlling <br />sediment releases from the mine. <br />L Stormwater Diversions <br />The following subsection describes the various stormwater <br />diversions currently in-place and proposed for the Level 6 portion of <br />the mine (includes the access road and pad). As described (and <br />previously document and approved in the 1997 CDPS - Stormwater <br />Certification No. COR-040199) before, Level 3 has been inactive <br />since 1978. The Level 3 area is not subject to stormwater run-on <br />because it is naturally diverted/absorbed on the scree/talus slope in <br />which it resides. There has been no observation of any run-on or <br />run-off with Level 3, however in the interest or providing a <br />conservative stormwater plan, diversion features are planned for the <br />Level 3 access road. Therefore, the following describes the various <br />stormwater diversions used for the Level 3 access road and both the <br />access road and pad for Level 6. <br />Stormwater diversions for the Access Roads: <br />• Run-on channels will be cut into the inside track of the access road <br />shoulders that are adjacent to the cut slope. These channels will <br />capture any stormwater sheet flow from the up-slope areas and <br />route the water to stormwater culverts. <br />• Stormwater culverts will be placed under the access road surface <br />and will capture run-on channel flows and route then to- rip-rap <br />baffles at the culvert outfall. <br />• Rip-rap Baffles will be comprised of cobble to boulder sized rock <br />and will significantly diminish outfall water energy thereby <br />allowing for particulates to settle from stormwater flows <br />Stormwater diversions for the Level 6 Pad: <br />• Contouring of pad work surface has been in place and slopes the <br />pad back towards the cut hill slope. For the purposes of this <br />SWMP, the Level 6 pad will continue to maintain this `sloped' <br />working surface on the pad outside the portal. This contouring <br />Page 13 of 37