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Yoast Mine <br />Phase I Bond Release Request (SL-4) May 2012 <br />All areas requested for bond release are shown on Exhibit A, SL -4 Phase I Bond Release, the <br />documentation and justification for structure retention is contained in Tab 20, Attachment 20 -1 <br />Permanent Structures and Features. All roads were regraded and narrowed to meet the <br />requirements of Rule 2.05.5(1)(b) and Rule 4.03.1(1)(f). <br />Small stock tanks and surge ponds are also utilized in the postmine grading operations to <br />minimize erosion and to provide water for livestock and wildlife. The locations of these ponds <br />are shown on Exhibit C, Post Mining Topography Map. <br />Postmine drainage channels (PM -8, 13, and 20) were designed and constructed to control runoff <br />and erosion. These channels were designed, constructed, and reconstructed to control, at least <br />the 10 -year, 24 -hour storm event. In most cases where grades are steep, the riprap used in the <br />construction of the channels is 3+ inches larger than the design specifies. This conservatism <br />used in the construction helps to ensure stability of the channels. In other less steep locations, <br />turf reinforcement material (TRM) is used to stabilize and prevent erosion in the postmine <br />channels. <br />The locations of these channels are shown on the attached Exhibit C, Post Mining Topography <br />Map, while the as -built profiles for these channels are presented on Exhibit E, As -Built Drainage <br />Profiles. The approved channel designs are included in the Yoast Mine Permit Application Tab <br />20, Backfilling and Grading. <br />These postmine drainage channels all ultimately flow to sediment ponds to ensure that water <br />quality leaving the permit area is within regulatory specified limits. The locations of these ponds <br />are also shown on the attached Exhibit C, Post Mining Topography Map. The designs and as- <br />built documentation is contained in the Yoast Mine Permit Application Tab 13, Facilities. <br />The following describes the accompanying maps and documents provided in this package to <br />further document the Phase I Bond Release request. <br />5 <br />