2020-03-24_PERMIT FILE - C1981019A (39)

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RULE 2 PERMITS ewui"� n n•aroro..»s:` ,•.tKa,t• vw., }3.F.sic,,savc:w,<•>.,^'a g,�yn,w+»:;arN r>,nt+.a.w.,ncva '.sr 144,416VeN4.**els;,..r.mE•trz< As discussed in detail in Section 2.05.3,the mining method proposed by Colowyo is referred to as open-pit multiple seam/single seam dragline mining. The overburden material from the initial boxcut area was deposited in a permanent valley fill. As mining progresses to the south, overburden material from each successive cut was backfilled into the previously mined out area. This cycle was repeated for the entire mining area. Because an open-pit mining technique is employed,the regrading and backfilling of the spoil material was as contemporaneous as possible behind the mined-out area to facilitate proper leveling of the overburden material. The mining techniques utilized was a dragline and truck/shovel operation. The backfilled mining areas will be graded to establish the approximate original contour and to blend in with the undisturbed areas outside the mining limits. Colowyo will grade all final slopes so that overall grades do not exceed 33%. Additional information on the backfilling and regrading plan are discussed further in Section 2.05.3 and Section 4.14. Where necessary, the spoil surface will be roughened by ripping or discing etc., to ensure a bond between the topsoil and spoil to reduce slippage. To date there is no evidence of topsoil slippage on reclaimed areas. A few small tension cracks resulting from settling of fill and topsoil have occurred in a few areas within a year or two after reclamation, but soon stabilize and begin to fill in. The final surface as shown on the Post-mining Topography Map (Map 19) will approximate the overall pre-mining grades. Appropriate cross sections that show the anticipated final surface configuration of the proposed permit area,in conjunction with the existing pre-mining topography, are shown on the Pre-mining and Post-mining Cross Section (Map 20). This final surface configuration also reflects an often neglected concept of providing topographic relief for wildlife habitat. The regrading plan reestablishes escape cover, south facing slopes for wintering big game populations and small drainages suitable as future location of stockponds necessary to achieve the post-mining land use. Colowyo has prepared this reclamation plan with the understanding that some aspects of current reclamation practices are still in the development stages. Therefore, a degree of flexibility has been provided to allow changes and modification as techniques are refined or expanded. Colowyo will continue to evaluate the results of its reclamation plan each year in consultation with the Division and take advantage of each opportunity to try new plant species and materials and new methods for seeding and erosion control. Given the last statement above a modified seed mixture(s), revegetation metrics, and bond release protocols designed to target specific post-mining land use components are presented within the context of this section (2.05.4) as well as the revegetation requirements, Section 4.15. In effect, reclamation occurring at Colowyo during 2008 and beyond will focus on the replacement of the two primary subcomponents of the pre-mining rangeland land use: 1) grazingland (for domestic livestock), and 2) wildlife habitat (specifically targeting sage grouse brood-rearing habitat). The replacement of these two land use subcomponents will be effected by replacement of two primary revegetation communities: 1) grassland and 2) sagebrush steppe, respectively. Additional "incentive" for this new reclamation approach will be the validation (and modification as Rule 2 Permits 2.05-18 Revision Date: 12/20/19 Revision No.: TR-135