2013-10-17_PERMIT FILE - C1982056A (4)

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discharge from Culvert RDA -7 -1 can more effectively be routed back to the Area 1 Pit rather than being carried through the Washplant Facilities area to Pond D. Given the current configuration of the area, Culvert RDA -5 -1 can also be eliminated, with the discharge from Culvert RDA -5a -1 passing directly through the existing natural drainage channel to the Area 1 Pit. With the planned road and drainage modifications, Culvert RDA -lb -1 will also be eliminated, with drainage from Ditch RDA -1a running parallel to the Haulroad B -1 Extension, and crossing under the Haulroad through Culverts RDA -1 -1 to Pond D. In addition, experience with temporary Ditch RDA -4a indicates that topography and natural drainage conditions combine to limit effective ditch flows and create ditch maintenance problems in several locations. In order to improve drainage flows and increase the area available for the next phase of refuse placement, TC proposed modifications to Ditch RDA -4a which would move a portion of the ditch upslope. This modification would slightly reduce the contributing drainage area and result in an increase in the overall gradient, so a revised SedCAD run was completed, and the ditch design was modified. In addition, it was determined that rather than route the drainage from Ditch RDA -4a along the length of the CRDA Haulroad, it would be more effective and reduce maintenance requirements to drop the drainage from this Ditch into the Area 1 Pit through a short riprapped channel segment, as shown on the series of drawings (1, 2a -2d, 3) in Exhibit 26C. Similar to the existing CRDA, the CRDA Expansion is designed to accommodate both temporary (winter) placement and permanent disposal of coal refuse materials generated by ongoing underground development and mining operations, and operation of the TCC coal preparation facilities. The coal refuse materials to be placed in the expansion area are essentially the same as the materials that have been placed in the existing CRDA, and have similar physical and chemical characteristics (ie: non -toxic and non -acid, refer to Table 20A, Waste Material Analyses). For the CRDA Expansion, coal refuse materials would continue to be hauled from the Foidel Creek Mine Facilities Area or the potential future Sage Creek Project Area, and placed in a controlled manner on the refuse pile using either TCC's existing mobile equipment fleet or contractor equipment. Any refuse materials hauled from the future Sage Creek operations and placed in the CRDA Expansion area, will be transported on existing designed haulroads and the County Road (RCR27). These materials will come from the same geologic units that are mined or affected at the Foidel Creek Mine, and therefore, will have similar characteristics, with little or no potential to adversely affect water quality, flows or vegetation; create public health hazards; or cause instability in the CRDA Expansion area. Permanent placement will involve dumping the material in piles or windrows, and then spreading and compacting the materials in uniform lifts of 12- inches or less, to 90 percent of maximum dry density (AASHTO). If field testing indicates that compaction requirements can be consistently met with thicker lifts, lift thickness may be increased up to a maximum of 24- inches. Proper moisture control will be important in assuring adequate compaction. Compaction will be verified through regular compaction testing and documentation of compaction results and proper construction in both the Construction Certification (30CFR77.214 -215) and the Quarterly Refuse Pile Inspection Report. In addition to regular compaction testing and monitoring of water levels, the design engineer (NWCC) will inspect (and test, as appropriate) key construction activities, including: 1) Foundation conditions following soil and cover material stripping; 2) Underdrain materials and construction (to be photo - documented consistent with the applicable requirements of Rule 4.09.1(11)(c)); 3) Coal refuse materials; 4) Initial and ongoing coal refuse placement (quarterly); and 5) Cover ands soil material placement and revegetation. A report will be prepared and submitted to the CDRMS within two weeks following each regularly scheduled quarterly inspection, and a copy will be retained at the mine site. If an inspection identifies potential hazards, TCC will notify the CDRMS promptly, and develop appropriate emergency protection and remediation plans. Temporary refuse placement (primarily during the winter months) will involve placement of refuse materials in temporary stockpile areas to avoid placement when these materials may be frozen. When prevailing weather conditions warm to the point where any frozen materials are thawed, the material which has been temporarily stockpiled will be re- handled, placed, and compacted, consistent with permanent placement practices. Initial CRDA construction will involve placement of up to approximately 3.0 MM cubic yards of refuse material to a height of approximately 100 feet. Subsequent progressive CRDA construction will result in refuse placement up to the maximum design height and capacity, with progressive soil and cover material stripping and stockpiling, and extension of designed drainage structures. As CRDA construction progresses, fill areas and benches will be completed and graded, and cover and soil materials will be replaced to stabilize and reclaim these areas. Both cover and soil materials may either be direct handled and placed or recovered and placed from stockpile, dependent on construction scheduling and equipment availability. A minimum of 4.0 feet of suitable cover (2.5 feet) and soil TR12 -81 2.05 -97.5 06/22/13