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Final Compensatory Mitigation and Monitoring Plan—Version 2.0 <br />Climax Mine Overburden Storage Facility Expansion (SPK-2013-00045) <br />March 2017 Bikis Water Consultants, a division of SGM Page 12 <br />location, a backhoe was used to dig a pit to a depth of four feet, the soil layers were logged, and <br />several samples were collected for physical and chemical analyses. <br />The results of the soil sampling found that a soil cap of varying thickness (loam, sandy loam, or <br />silt loam in texture) with some coarse fragments was placed in the area by Climax (associated <br />with reclamation activities), and that this cap is not acid-producing. Beneath the soil cap are a <br />coarse waste rock cap and sandy tailings. Based on the mitigation site grading plan, some of <br />the tailing material may need to be excavated in areas before suitable substrate material is <br />placed using area soil salvaged by Climax. Climax has a large amount of salvaged topsoil and <br />subsoil from previous soil salvage activities already available for this purpose. The relatively <br />large amount of good quality water that will be provided to the site and the downward <br />percolation of water will eliminate any potential effects to the root zone of wetland plants from <br />the underlying tailing material. <br />5.2.3 Vegetation Communities <br />The Lake Irwin area is presently relatively unvegetated shallows (see photographs in Appendix <br />B). Wetland plants have invaded portions of the shoreline including some sedges, rushes, and <br />willows. <br />6.0 MITIGATION WORK PLAN <br />6.1 CONSTRUCTION METHODS - OVERVIEW <br />The overall plan for Lake Irwin is shown in Figure 4. Three wetland/aquatic habitat types will be <br />created: shallow aquatic bed, emergent wetland, and scrub-shrub wetlands (see Table 1), with <br />most of the site being scrub-shrub wetland, since most of the wetlands to be impacted in <br />McNulty Gulch are this type. A total of 36.312 acres of mitigation will be created, which <br />represents a mitigation ratio of 2.2:1 consistent with input from the U.S. Environmental <br />Protection Agency (EPA) and Corps. This includes approximately 450 linear feet (0.10 acre) of <br />perennial channel that will be created as part of the new outfall channel to the Eagle River <br />watershed. <br />The design concept is to take advantage of the water inflows to the area to sustain <br />wetland/aquatic habitats with connectivity to the adjacent, native landscape to the west. As <br />shown on Figure 4, the existing Lake Irwin (approximately 10 acres) will be filled and areas