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control any run-on to this portion of the mine thereby affectively eliminating any <br />runoff as well. <br />Level 6 is the currently active portion of the mine and requires maintenance and <br />updating of the existing management practices. The access road no longer shows <br />signs of stormwater erosion, however the Level 6 pad needs to proactively control <br />stormwater infiltration in order to control any acid rock drainage through the <br />waste rock. Several best management practices are already in place, however in <br />the interest of providing a more comprehensive stormwater plan, additional <br />management practices were recently constructed and are more fully described in <br />the next Section by type. <br />4. Stormwater Management Controls <br />Various stormwater management controls have been in place for a number of <br />years since the implementation of the first CDPS stormwater permit (May 2, <br />1997: Colorado Discharge Permit System - Stormwater Certification No. COR- <br />040199). These management practices were upgraded recently (March, 2008) as <br />per our previous stormwater management plan described. Since were historic <br />signs of stormwater erosion along the Level 6 access road, and the potential for <br />acid rock drainage at the toe of the Level 6 waste rock pile due to stormwater <br />communication with the waste rock materials, a series of bmp efforts were placed <br />in order to control these concerns. A summary of the proposed management <br />practices to address the Level 6 access road concerns as well as the Level 6 waste <br />rock concerns include: <br />Level 6 Access Road <br />Setting: The portion of the Level 6 access road within the mine permitted area <br />and falls within stormwater permit boundaries is approximately 0.25 miles along a <br />steeply sloped hillside. As such, the road provides a stormwater path of travel for <br />overland flows from the above hillside. Historically, these flows sought a low <br />point where erosive materials have been cut through to create a stormwater <br />channel at the bottom of the road, just prior to entering the Level 6 pad. It <br />appears that the combined flows over the distance of the road have created this cut <br />over the past several years. In order to abate this issue the following features were <br />constructed; <br />• A `run-on' channel along the inside track of the road (immediately adjacent to <br />the toe of the hillside) was cut in order to keep run-on from the above natural <br />slope from entering the road footprint (refer to Photos attached). <br />• The flows within this run-on channels are being routed to five roll and dip <br />water bars placed at equal distances along the length of the road. These roll <br />and dip water bars were constructed using Bureau of Land Management and <br />US Forest Service guidance (Keller and Sherhar, 2003). Specific details <br />regarding their construction are depicted in Figures 2 and 3. <br />The flows routed through the water bars are released to the hillside on the <br />downhill side of the road, and carried through baffles comprised of large <br />cobble to boulder-sized materials, or coarse alluvium. These baffles will <br />dissipate flow energy and allow for sediment settling. They will also disperse <br />Page 6 of 16