Laserfiche WebLink
Stormwater Management Plan <br />Exhibit U — Attachment U -3 <br />construction work plan (Attachment D -1) to control sediment and stormwater prior to, <br />during, and after construction activities. <br />e. If deemed necessary by the State Engineering Office, Wildcat will construct a lined water <br />storage augmentation pond at the former Idaho mill site. (Exhibit U, Figure SWMP -1). <br />During construction, erosion and sediment controls will be in place to eliminate sediment <br />being released to the La Plata River (Attachment D -6). The augmentation pond will be <br />constructed in the location of a former tailings pond. Stormwater runoff from the 10 year <br />24 hour storm (designed storm) will be directed around the proposed structure in a rip -rap <br />lined channel and a rip -rap outlet (FHWA, 1995). A summary of the flow volumes and <br />design structures for specified drainage areas is presented on Table SWMP -1 for the <br />drainage basins delineated on Exhibit U, Attachment U -3, Figure U -1. <br />f. The Chief Tunnel vicinity and the May Day No. 2 portal have areas that require minimal <br />construction activity to remove debris currently located in the vicinity of Little <br />Deadwood Gulch. These areas will be reclaimed per DRMS regulations. Stormwater <br />management and sediment control measures will be implemented to minimize potential <br />impacts to the waters of the State during construction activities. The Chief Tunnel -Little <br />Deadwood Gulch channel (Exhibit U, Figure SWMP -1) is designed to convey the peak <br />flow from the 100 year 24 hour event. The May Day No. 2 portal channel and culvert <br />design and installation criteria are summarized in Exhibit U, Attachment U -3, Figure <br />SWMP -1. <br />Additional mining or exploration related activities will implement appropriate BMPs (Exhibit U, <br />Attachment U -3, Appendix U -1) to manage sediment and stormwater from the 10 year, 24 hour <br />design storm. <br />Winter road maintenance will include plowing, storing, or blowing snow in designated areas. <br />BMPs such as rock berms, and drains, will be implemented in these locations to control <br />snow /stormwater runoff and sediment. <br />2. Proposed Sequence of Activities: Once the DRMS permit is issued, the following construction <br />activities will commence: <br />a. Install access road BMPs and construct the access road from County Road 124 to the La <br />Plata River; <br />b. install or repair other BMP structures; <br />c. improve or construct structures on the pre existing access road including berms, swales, <br />debris basins, and ditches; <br />d. stabilize the May Day No. 1 and Chief portals; <br />e. If necessary construct the water augmentation pond at the former Idaho Millsite; and <br />f. reclaim of the Chief Tunnel (Attachment D -4), Chief Tunnel drainage (Attachment D -4) <br />and May Day No. 2 portal (Attachment D -3) areas <br />3. Estimates of the total affected area, and the area and location expected to be disturbed by <br />clearing, excavation, grading or other construction activities includes: <br />a. Total affected area including roads, and exploration, and mine operations (31.4 acres); <br />Wildcat Mining Corporation <br />May Day Idaho Mine Complex — 112d Permit Application <br />Revised August, 2011 <br />Exhibit U — Rule 6.4.21 <br />Page 6 of 31 <br />