2021-08-06_PERMIT FILE - C1982056A (2)

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NMD (Panels 12 -Right through 16-Ri2ht, PR 99-05 The geology description provided in PR -03 is also applicable for the NMD. One item to note is that TCC discontinued pumping from the Fish Creek Borehole for a period of approximately 18 months. When pumping recommenced the total recoverable iron and total dissolved solids concentrations increased to approximately 17 mg/l and 7,200 mg/l respectively. TCC is applying caustic soda to reduce the total recoverable iron concentration as per its CDPHE discharge permit. TCC believes the elevated concentrations are the results of the water stagnating in the underground sump. Once this pool of water is discharged, TCC believes the concentration will return to levels previously reported for the Fish Creek Borehole. TCC will continue to monitor the concentration, and anticipates the concentration to return to historic levels by late summer, 2000 or 2001. In regards to future impacts, TCC will not discontinue pumping of the underground sump for extended periods of time. This will eliminate the potential for the above situation to occur in the future. Once mining is completed at the facility, no further discharging will occur. Based upon this, there should be no impact to the postmining land use. Coal Refuse Disposal Area (CRDA TR92-15 TR95-21 MR08 233 TR09 67) The original Coal Refuse Disposal Area (CRDA), located to the southwest of the Area 1 Pit, as shown on Map 24, Surface Facilities, has been designed to hold approximately 3,000,000 cubic yards of material. The CRDA is designed to accommodate temporary placement and permanent disposal of coal refuse materials generated from the preparation plant, excess coal development waste material from the mine, or a combination of preparation. plant and mine waste material. This material or combination of materials will be hauled to the pile using either TCC's existing mobile equipment fleet or contractor equipment. The original design of the CRDA was contracted to CTL/Thompson. The design was revised and updated to reduce the overall footprint and address operational placement and final grading concerns, by Northwest Colorado Consultants. Both the original design and revisions are documented in Exhibits 26A, 26A-1, and 26A-2. Within 30 days of start-up of the preparation plant, a sample of the waste material generated from the preparation plant was obtained and analyzed to verify the assumptions used for the pile design presented in Exhibit 26A. TCC forwarded results of this analysis to the Division along with a certified statement from a registered P.E. summarizing the results of the analyses as compared to the original design assumptions. The surface runoff/diversion system design for the pile was developed in-house by TCC and is presented as Appendix D to the CTL/Thompson Report. The locations of the CRDA and associated drainage features are shown on Map 24, Surface Facilities. As shown on Exhibit 26A, Figure 1, the CRDA is constructed west of the reclaimed valley to the west of the Area 1 Pit. Prior to construction, approximately 18 inches of topsoil from within the pile footprint were removed and placed in topsoil stockpile SF -12 (see Map 29). During reclamation of completed pile benches, suitable cover materials and topsoil will be redistributed over the face of the pile. Direct placement of topsoil will occur to the extent possible during the bench reclamation/pile extension process. It is anticipated that topsoil replacement will stay one bench below the active working zone of the pile. During construction of the CRDA, inactive portions of topsoil stockpile SF -12 will be seeded with the topsoil stabilization seed mixture at the first appropriate opportunity following stockpiling operations. Table 49A, Topsoil Stockpile Summary, has been revised to show the potential modification to the existing stockpile SF -12 resulting from the construction of the refuse pile. Also, the table presents information for all other Twentymile topsoil stockpiles. The stockpile identification numbers in the table correlate with the stockpile designations presented on Map 29. Spoil/subsoil material will be used as suitable, non-toxic cover, to be placed over completed refuse benches prior to topsoil replacement. During development of the refuse pile, spoil/subsoil material will be selectively removed from within the footprint of the pile. The spoil/subsoil will normally be hauled directly to an active reclamation area and spread over the completed refuse bench. In cases where direct placement is not operationally feasible, cover materials may be temporarily stockpiled within the pile footprint or in adjacent areas. After placement of the spoil/subsoil material, the area will be topsoiled, as previously described. Redistributed topsoil will be seeded with the pastureland seed mixture. TR09-67 2.05-96 06/16/09