2008-05-28_REVISION - C1981019 (2)

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Section 4.15.8) "DWM Wangnild discussed the possibility of changing reclamation efforts in the new [South Taylor] permit area. Specific changes would ideally be focused on dramatically varying topsoil depths in an effort to mimic natural depths and thus provide more suitable environments for woody species establishment. One example of this would be to create some sites with extremely shallow topsoil designed at reducing grass stand establishment and their resulting competition with shrubs for water and soil nutrients. Another example would be to create other sites with extremely deep topsoil depths. These sites would ideally benefit woody species like aspen and chokecherry." In this regard, and depending on site-specific opportunities, Colowyo will utilize the planned post-mine topography (PMT) to help identify candidate (and prime candidate) areas for targeting Sagebrush Steppe post-mining communities. Key to this analysis will be considerations for the risk of erosion and for long-term stability. One such "threshold" value to be used for this analysis will be a slope break at 10% gradient. Slopes greater than 10% will be considered too risky to make attempts at targeting shrub communities, largely due to snowpack runoff scenarios that can often lead to serious erosion and stability failures. For example, snowmelt runoff in the early 1980s caused widespread and severe down-cutting of the natural drainages to the immediate west of Colowyo. Unless proven otherwise by hydraulic and/or erosion modeling, slopes less than 10% will be identified as candidate locations for shrub community establishment. Another "threshold" value to be used in the PMT analysis is the size of units that may exhibit slopes 10% or flatter. Areas small in areal extent (e.g., less than about 5 acres) will not be identified to receive shrub-conducive metrics. Only those areas that are larger will be identified. The exact size cutoff will be at the discretion of the reclamation coordinator, however, a practical limitation must be defined given the complications realized by the change in revegetation targeting measures. Where Sagebrush Steppe revegetation will be targeted, Colowyo would apply shallow lifts of topsoil (< 8 inches, ideally 4-6 inches). To maintain topsoil replacement balances, thicker lifts of topsoil (> 8 inches, occasionally up to 3-4 feet) can be placed along the groin of opposing slopes (drainage-ways). On long slopes steeper than 10%, topsoil distribution using pushdown techniques may be altered to facilitate thin layers near the upper shoulders of the slope, with thicker layers near the bottoms. In this manner, the lower elevation areas that tend to catch more snow will receive and store greater quantities of moisture with the hope that some of the mountain shrub seed within the seed mix will be presented with enhanced opportunities for growth and development, especially taxa such as snowberry. The shoulders of the slope, where soil thickness has been reduced will present greater opportunity for sagebrush to develop given reduced competition from cool-season grasses. In order to facilitate proper accounting of the topsoil resource, topsoil placement on specific areas will be tracked by load counts of the equipment involved. In cases where only Sagebrush Steppe acres are reclaimed in one season, replacement volumes may be less than the currently approved 8-inch average (in the original permit area). This does not cause undue harm on the resource as the "left over" material will be utilized in the development of deeper soil areas elsewhere in the reclamation progression. All activities will be accurately and fully described within the confines of the Annual Reclamation Reports, that include topsoil balance tracking. Another directive with regard to topsoil distribution (at the discretion of the field supervisor) will be instruction to equipment operators to NOT engineer the final surface, but to the contrary leave it in a state of disarray with thick and thin spots of topsoil. The primary directives in this regard 2.05-47 Revision Date: 3/14/08 Revision No.: TR-72