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0 <br />1 <br />GENERAL LOCATION AND DESCRIPTION <br />This report presents the Wildcat Mining Corporation final drainage study and drainage system <br />design for the May Day Idaho Mine Complex — Wildcat Road. The design and analysis of this <br />site has been performed in accordance with the La Plata County Road, Bridge and Drainage <br />Specifications and Standards, current Code of Ordinances and Urban Drainage and Flood <br />Control District, Urban Storm Drainage Criteria Manual, Volumes 1, 2, & 3, June 2001. <br />Drawings, tables, and design calculations are included in the appendix of this report. <br />Site Location <br />The site is the Idaho and May Day Mine and Mill Complex located north of Hesperus, west of <br />County Road (CR) 124 (aka La Plata Canyon) at 4432 CR 124. A portion of the site is located in <br />the NE 1/4 of the SW 1/4 and the SE 1/4 of the NW 1/4 of Section 28, Township 36 North, <br />Range 11, West of the New Mexico Principal Meridian, County of La Plata, State of Colorado. <br />Site Description <br />The entire mine site is approximately 296 acres. The scope of this project is to construct a road <br />from the country road to the La Plata River and the amount of disturbed area that is considered <br />for this report is 2.80 acres. The topography for this site generally slopes southerly at slopes <br />ranging from 1.0% to 71 %. The soils within the site are sandy loam, cobbly loam and Riverwash <br />translating into Hydrologic soils group Type B and C. The vegetation is native trees, shrubs, <br />grasses and weeds. <br />Proposed Project Description <br />The project consists of a base operations site with gravel parking lot with out buildings, a new <br />gravel road with drainage swales and a proposed water - quality /detention pond. <br />IP DRAINAGE BASINS AND SUB - BASINS <br />Major Basin Description <br />The existing drainage patterns for the site are to be maintained. The site is divided into five sub - <br />basins, four of which drain to the proposed water - quality /detention pond east of the proposed <br />road at a low point. Flows are then routed directly to the La Plata River that is directly west of <br />the proposed road. <br />Portions of the site located within 200 feet of the river are inside of the 100 -year floodplain, Zone <br />A as indicated on the Flood Insurance Rate Map Community -Panel Number 08067C0455F, <br />dated August 19, 2010, for la Plata County, Colorado (Appendix A). <br />Site Sub - Basin Description <br />The sub - basins were determined based upon topography. The historic condition is held so that <br />the offsite flows from the north are routed through proposed storm sewer system (swale) and <br />outfall to the proposed water - quality /detention pond. <br />The overall basins have been divided into sub - basins in order to size the storm sewer system. <br />Basins A, B1, B2 and P drain to the proposed water - quality /detention pond via overland or the <br />proposed roadside swale. Basins OS is represented by an area along CR 124 that historically <br />drains to the south and will continue to do so. <br />I =M <br />ClC ASSOCtATCS <br />Page 1 <br />