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H. There will be some long -term settlement of both disposal areas. We recommend overbuild of <br />approximately 5 percent in the central portion of both fill areas in order to maintain long -term drainage. The <br />surface of the fill should be designed with a slope of 5 percent away from the head of the fill. The fills should <br />drain to ditches on both sides of the fill. <br />Given that these drainage features encompass the entire temporary clay stockpile, topsoil pile, and light -use road, <br />and that these disturbances represent only a small portion of the total excess overburden stockpile area, they should <br />provide effective drainage and sediment control for the proposed temporary activities. A temporary fueling station, <br />consisting of a fuel tank and lined secondary containment, will also be established at the stockpile location. The <br />stockpiled clay will be recovered and placed as cover material on the western slope of the Refuse Pile as soon as <br />ongoing refuse placement and grading bring this area to the final design elevation and grade. The light -use road <br />will be narrowed and ripped, stockpiled topsoil will be replaced on the associated disturbance areas, and all <br />disturbed areas will be reseeded with the permanent rangeland seed mix. <br />4) Subsurface and Surface Drainage - Small drainage ditches will be constructed downslope of the temporary <br />stockpiles to minimize water running over and down finished slopes of the CRDA. Also, it was recommended in <br />Exhibit 26A -1 that temporary drainage ditches be established along the eastern edge of the benches as they are <br />constructed, to prevent excessive surface runoff from flowing over the finished /compacted slope of the CRDA. <br />The specific recommendations for these temporary drainages are presented in Exhibit 26A -1. <br />Coal Refuse Disposal Area Expansion (MR07 -226, TR09 -67, and TR10 -72) <br />With the existing CRDA nearing its design capacity, TCC completed an evaluation of required refuse disposal <br />requirements through the end of the Foidel Creek mine life. Included in this evaluation was an assessment of the <br />potential refuse disposal requirements for the nearby Sage Creek Project, in the event it proceeds to development <br />and full -scale production. The evaluation of potential future refuse disposal requirements indicates that a maximum <br />of approximately 20.0 MM cubic yards of additional capacity will be required to address reasonably foreseeable <br />future needs. Based on the calculated refuse disposal capacity requirement, TCC contracted with Northwest <br />Colorado Consultants (NWCC) to complete site geotechnical investigations and detailed design and phasing plans <br />for phased construction of a 20.0 MM cubic yard CRDA Expansion, along with all associated structures and <br />facilities. The proposed CRDA Expansion is located immediately adjacent and to the east of the existing CRDA, <br />and the existing CRDA on the west, natural ridgelines to the east and south, and the engineered, benched refuse fill <br />toe on the north, effective bound and provide containment for refuse fills. Designs for the associated facilities <br />include required access, drainage control structures, and soil and cover material handling plans and stockpiles. <br />Site geotechnical investigations are required to provide foundation and soils information for design, permitting, and <br />construction of the Coal Refuse Disposal Area Expansion. The area proposed for the Refuse Pile Expansion is an <br />area of reclaimed mine spoils immediately adjacent and to the east of the existing CRDA, as shown on Maps 24, <br />Mine Facilities and Freshwater Systems, and EX26C -M1, Surface Facilities — Refuse Pile Expansion. Site <br />geotechnical investigations for the CRDA Expansion involved completion of five, 4 -inch hollow -stem auger <br />sample holes to depths of 20 -40 feet; excavation of seven shallow (ten to fifteen feet in depth) backhoe test pits; <br />and collection, examination, and testing of soil samples. There will be a total of no more than twelve auger holes <br />and test pits. <br />No new roads were built, sample locations were accessed overland using rubber -tired equipment, and access was <br />limited to periods when the ground was dry or frozen in order to minimize surface disturbance. In order to <br />minimize surface disturbance, soil removal was limited to the immediate area of each auger -hole or test pit, with <br />soil material being windrowed to the side of the disturbance area, and re- spread immediately following completion <br />of drilling /excavation /sampling and backfilling. Site runoff from the li►nited disturbance areas was addressed <br />through the use of alternative sediment controls consisting of straw wattles, placed ands staked immediately <br />downgradient of each disturbance area. Auger drilling is a dry drilling operation, so no mud pits were required, and <br />no discharge of drilling fluids occurred. Because the auger -holes and test pits were in reclaimed mine spoils on a <br />hillslope. the potential for intercepting any significant quantities of ground water was negligible. Air was not used <br />a circulation medium, so dust generation was not a concern. <br />TR12 -80 2.05 -97.2 09/04/12 <br />