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Stormwater Management Plan <br />Site Description <br />The May Day Idaho Mine Complex is located in Section 21 and 28, T28N, R1IW, Lat 37.352765; Long <br />108.074094, La Plata County, Colorado. The access road into the May Day Idaho Mine Complex <br />originates off County Road 124, near the community of Mayday, Colorado approximately 16 miles <br />northwest of Durango, Colorado. The mine site is located on Little Deadwood Gulch a tributary to the La <br />Plata River which ultimately drains into the Animas River. <br />Access site road foundation consist of unconsolidated river gravels on the west side of the La Plata River <br />and bedrock limestone and consolidated sandstone on the east side. Construction activities will be <br />focused on establishing road access from the west side of the La Plata River across river alluvium to the <br />east side of the River. Pre-existing roads built in or around 1930 will be used to the maximum extent <br />possible to support mining activities. Pre-existing roads will be upgraded and maintained to comply with <br />stormwater management control requirements, to allow access for emergency vehicles, and mine <br />equipment while implementing road safety features. Upgrading features will include temporary BMPs, <br />constructing debris basins, ditches, swales, snow storage areas, berms, culverts, and check dams. <br />1. Nature of Construction (Mining) Activities At The Site: <br />a. If necessary, a storm water management detention pond will be constructed <br />The operator intends to process the 7,400 ton historic stockpiled ore. The stockpiled ore <br />is located underground within the stope, inside the May Day No. 1 portal. <br />b. Surface ore stockpile located near May Day No. 2 (500- 1,000 tons), Lamb portal bench <br />(1,000-2,000 tons), and the former Idaho Mill site (2,500 tons), will be processed as <br />determined by the price of gold and silver. (Stockpiled ore locations are illustrated on <br />Figure D-5). <br />c. The Chief Tunnel -Little Deadwood Gulch channel is constructed to convey the peak flow <br />from the 100 year 24 hour event. The May Day No. <br />Winter road maintenance will include plowing, storing, or snow blowing. BMPs such as rock <br />berms, and drains, will be implemented in these locations to control snow/stormwater runoff and <br />sediment. <br />2. Proposed Sequence of Activities: Once the DRMS permit is issued, the following construction <br />activities will commence: <br />a. renovate LaPlata River bridge; <br />b. install or repair BMP features; <br />Sunrise Mining, LLC <br />Revised August 9, 2017 <br />Page 5 of 30 <br />