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IRIS <br />MITIGATION AND DESIGN, INC. <br />SCHWARTZWALDER MINE PHASE 1 - UPSTREAM CUTOFF WALL AND LOW FLOW BYPASS <br />PIPELINE - BIOLOGICAL ASSESSMENT <br />2. PROJECT DESCRIPTION <br />2.1 Location <br />The Site is located approximately 5 miles northwest of the junction of Colorado State Highway 93 and <br />56 Avenue north of Golden, Colorado (see Figures 1 and 2). The Site is located along a fairly <br />undeveloped section of Ralston Creek approximately 2 miles upstream of Ralston Reservoir and is <br />depicted on the U.S. Geological Survey Quadrangle map for Ralston Buttes, CO in Section 25, <br />Township 7 South, and Range 71 West: Latitude 39° 50' 48.74" N and Longitude 105° 16' 55.32" W. <br />The property includes the majority (87 percent) of Section 25 of which 57 acres were originally <br />permitted for mining under Colorado Mining Permit # 77 -3000. The mine permit area was reduced to <br />approximately 46 acres in 2001 (DRMS, 2001). <br />2.2 Definition of Action Area <br />The action area for the cutoff wall includes approximately 1 acre of previously disturbed and <br />undisturbed PMJM upland and riparian habitat (see Figures 2 through 4). The majority of the action <br />area includes an existing 40 -foot unpaved road crossing of Ralston Creek located between the <br />northern and southern waste rock piles (see Figures 3 and 4). Ralston Creek flows beneath the road in <br />this location via two culverts (36 -inch and 72 -inch in diameter). The portion of Ralston Creek up- <br />gradient of the cutoff wall is a largely undisturbed riparian area which is further described below. The <br />section of Ralston Creek downstream of the cutoff wall was previously impacted due to mining <br />activities. In the vicinity of the Project area, Ralston Creek and its associated riparian corridor have <br />been previously impacted due to construction of the existing unpaved road and placement of the <br />northern and southern waste rock piles, which are now capped and re- vegetated with upland grasses. <br />The riparian corridor downstream of the cutoff wall is narrower than the upstream section and remains <br />so through the majority of the Site. <br />The previously- disturbed, unpaved road crossing of Ralston Creek and riparian areas upstream and <br />downstream of the road crossing will be excavated to install the cutoff wall. This concrete wall will <br />impact previously disturbed and undisturbed upland and riparian areas upstream and downstream of <br />the road crossing, as well as the road crossing itself. Impacts are covered in detail in Section 5 of this <br />report. <br />Page 5 August 2011 <br />