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Stormwater Management Plan
<br />c. improve or construct erosion control features on the pre-existing access road including
<br />berms, swales, debris basins, and ditches; and
<br />d. maintainf 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 (45.7 acres);
<br />b. New access road plus the base of operation (3.1 acres);
<br />c. May Day Idaho Mine Complex historic road maintenance (includes delineating snow
<br />removal disposal areas benches, and fences, (12.8 acres);
<br />d. Ditches/rock berms at the Idaho, (16.5 acres) May Day No. 1 (6.5 acres), May Day East
<br />(0.8 acres) May Day No. 2 (3.3 acres), May Day No. 2 East (0.5) and May Day No. 3
<br />mine bench (5 acres);
<br />e. Existing benches at the May Day 3 (5 acres) and the Chief portal (0.5acres);
<br />f. Repair the maintenance /core storage structure (former Idaho Mill Building) (acreage
<br />included in the former pond is calculated in the footprint); and
<br />g. Existing roads (12.8 acres) and bridge will remain after mining.
<br />4. Site Soil Information: Existing soils (Exhibit I) data for the drainage area within the permit and
<br />affected areas are provided through the National Resource Conservation Service (MRCS) Custom
<br />Soil Resource Report for the La Plata County Area, Colorado. The soil report identifies:
<br />• Pastorius cobbly loam (8,000-9,000 feet) and Pescar fine sandy loam (6,500-8,000 feet)
<br />in areas adjacent to and including the access road;
<br />• Nordicol very stony sandy loam (7,800-10,000 feet) for the May Day No 1 area, May
<br />Day No 2;
<br />• Cryothents Rubble for the Lamb portal area; and
<br />• Nordicol very stony sandy loam (8,000-10,000 feet) and Leadville very stony sandy loam
<br />(7,800-10,000 feet) for the former Idaho millsite location.
<br />The soils are naturally thin, well drained, well vegetated rocky slopes. Historical disturbed mine
<br />areas were not reclaimed however native volunteer vegetation growth has stabilized soils within
<br />the historically (pre -1985) affected area.
<br />Existing vegetation: Vegetation affected by mining is a mixed coniferous and deciduous forest
<br />(Exhibit J) with specific vegetation types generally having the same species present but varying in
<br />dominance. The mixture of vegetation assemblages are influenced by topographic aspect and to a
<br />lesser degree by elevations, and geologic conditions. Topographic slope is a factor only in the La
<br />Plata Floodplain. Primarily, the dominant tree species for the site are aspen and Douglas fir with
<br />ponderosa pine, white fir, blue spruce, and lumber pine also present. The dominant shrub species
<br />are gamble oak and mountain snowberry. Other shrubs found in the community include
<br />chokecherry, wild rose, black elderberry, golden current, Oregon grape, Rocky Mountain maple,
<br />mountain lover, thimbleberry and serviceberry. The herbaceous groundcover includes the
<br />following: bluegrass, puline, western wheat grass, yarrow, common nettle, whipple penstemon,
<br />dandelion, Fremont goosefoot, salsify, bracken, clover, American vetch, medowrue, goldeneye,
<br />Sunrise Mining, LLC
<br />Revised August 9, 2017
<br />Page 6 of 30
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