Laserfiche WebLink
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 />historic erosion channel that has been created as a result of the access road <br />acting as a conduit for stormwater. However, as stated in the introduction to <br />this Section, we have added a series of additional bmps (water berms, <br />enhanced run-on channel) to control this issue. Existing management <br />practices such as the revegetated perimeter berms, are holding sediment in <br />place. In addition, the natural setting (porous slope, low snow accumulation) <br />lends to controlling the amount of stormwater potential. These combined <br />attributes appear to be controlling sediment releases from the mine. <br />i. 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 />• A Run-on channel was cut into the inside track of the access road <br />shoulders that are adjacent to the cut slope. This channel captures <br />any stormwater sheet flow from the up-slope areas and routes the <br />water to the roll and dip water bars. <br />• Stormwater roll and dip water bars were constructed in the access <br />road surface and will capture run-on channel flows which will <br />route the stormwater to baffles at representative outfall locations. <br />• Baffles are comprised of cobble to boulder sized rock, or coarse <br />alluvium and 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 />routes all drainage back towards the portal and into the stormwater <br />ditch system that will route water into underground. In addition, a <br />Page 9 of 16