2014-10-15_PERMIT FILE - C1982056A (7)

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Previously, during evaluation of the CRDA, as permitted under TR -15, a chemical analysis of the processed waste material was completed, with the results presented as Table 20A, Waste Material Analysis. Based on this analysis, it appears the refuse materials are not potentially toxic - forming or acid - generating. The previously referenced CTL/Thompson report addressing the CRDA design and geotechnical evaluation includes a conservative estimate of the maximum quantity of water projected to drain from within the pile (see Exhibit 26A, page 17). The estimate is based upon the assumption that 3 inches of water infiltrates into and discharges from the pile on an annual basis. The analysis further assumes that discharge from the pile occurs during a one -month time period. Under these conditions, the average calculated flow from the drain is 0.2 cfs for the month drainage occurs. The discharge from the refuse pile rock drain will be routed to Pond D. Given the very limited volume of rock drain discharge relative to the surface water runoff contributions typically received by Pond D, no adverse water quality impacts are anticipated as a result of construction of the waste pile. Pond D will continue to be monitored for the applicable NPDES discharge permit parameters as required. The permanent diversion ditches on and around the perimeter of the CRDA (see Map 24 and Exhibit 26A, Appendix D) were established prior to constructing the refuse pile. The uppermost portion of the west side diversion ditch segment RDA -lb, however, was temporarily aligned slightly to the east of the location depicted on Map 24 in order to avoid the established topsoil stockpile (SF -6) in this area (see Exhibit 26A, Figure 2). Topsoil Stockpile SF -6 remained in its original location and will be utilized as the initial topsoil source for reclamation of the refuse pile benches. In the event Topsoil Stockpile SF -6 has not been reduced through topsoil replacement to the degree necessary to allow construction of the final configuration of ditch RDA -lb once the pile is developed to this elevation, any portion of Topsoil Stockpile SF -6 conflicting with the final ditch alignment will be relocated and the permanent diversion ditch will be established between the existing sections. TCC does not intend to riprap the temporarily located portion of Ditch RDA -lb, but will riprap the ditch when the final alignment is established. In order to facilitate the establishment of vegetation in permanent diversion Ditch RDA -2, temporary rock check - dams will be installed in selected segments of the ditch. The design of these rock check -dams can be found in Exhibit 26 -a(1), Refuse Pile, Rock Check -Dam design. It should be noted that these dams will not exceed one foot in height, and extend across the 8 -foot wide ditch bottom. The 12 -foot rock dams will extend up the ditch sideslopes to the flow -line. The rock check -dams will be placed according to the following spacing interval: Slopes 1 percent or less - every 100 feet, 2 percent slope - every 50 feet, 3 percent slope - 3 dams per 100 -foot segment of ditch, 4 percent slope — 4 dams per 100 -foot segment of ditch, 5 percent slope - 5 dams per 100 -foot segment of ditch, and 8 percent slope - 8 dams per 100 -foot segment of ditch. Temporary diversion ditches designed to convey the 100 -year, 24 -hour storm runoff will be cut -in approximately 50 feet upslope from the working area of the CRDA as pile construction progresses. The temporary ditches will be established in areas stripped of topsoil, and are intended to divert surface runoff away from the exposed coal waste materials during construction of the pile. TCC estimates a maximum of six temporary ditches will be established throughout the life of the pile. Coal Refuse Disposal Area Modification (TR95 -21, TR05 -49, MR08 -233) The CRDA construction sequence and final grading are modified as reflected in Exhibit 26A -1. The modification of the construction sequence and final grading will result in a stable refuse pile configuration in accordance with the requirement of the DMG regulations. The bench ditch design is presented in Exhibit 8M. It should be noted the bench design is adequate to pass runoff from the 100 -year, 24 -hour event. All of the provisions provided in Exhibit 26 will continue to be followed by TCC, except as modified by Exhibit 26A -1. The modification presented in Exhibit 26A -1 can be summarized as follows: 1) Segmented Construction — The requirement to place and compact the fill in 24 -inch lifts will be followed, with testing of every other lift to verify compaction requirements are met. The southern portion of the CRDA will be the primary temporary stockpiling area, although the entire footprint of the pile can be used for temporary stockpiling of refuse material to allow for temporary storage of material during the winter, when adequate compaction may not be feasible, and to allow water to drain from the refuse prior to placement and compaction. TR09 -67 2.05 -97 06/16/09