2010-11-19_PERMIT FILE - C1992081A (3)

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As part of the 2,000,000 ton per year unloading system facility modification, to satisfy air emission permit requirements, HGTI will reclaim approximately 2.8 acres of previously disturbed area that drains to the Truck Loop Pond. Coal refuse located in the excess stockpile area will be removed (see Attachment 12-1, Exhibit 12-2 [Revision 5, TR-04 Incidental Permit Boundary Change, dated 8/99] for the location of the excess coal stockpile area), and the area will be topsoiled and reseeded with seed mix #1 (see Tab 20, Revegetation Plan). These reclamation activities will reduce the disturbance area by approximately 57 percent and consequently, the amount of runoff to the pond generated by the 10-year, 24-hour storm event. Rail Loop Pond Appendix 12-1 also contains a SEDCAD4 modeling demonstration that shows the existing configuration (1.91 acre-feet of storage) is sufficient to detain runoff from the 10-year, 24-hour storm event and, that the as-built pond configuration meets the requirements of Rules 4.05.6 and 4.05.9. Note that there is a slight discrepancy between the "as-built" storage capacity (1.69 ac-ft) and the SEDCP,D model capacity (1.91 ac-ft). This is due to slight differences in how the surveyed as-built values versus the SEDCAD generated values were calculated. Both instances show there is sufficient capacity to detain runoff from the 10-year, 24-hour storm event. As part of the 2,000,000 ton per year unloading system construction, to satisfy air emission permit requirements, HGTI will reclaim approximately 4.7 acres of previously disturbed area that drains to the Rail Loop Pond. The area will be backfilled, graded, topsoiled and reseeded with seed mix No. 1 .(see Tab 20, Revegetation Plan). The reclamation will reduce the disturbance area by approximately 34 percent and consequently, the amount of runoff to the pond generated by the 10-year, 24-hour storm event. Small Area Exemptions Topsoil Stockpile: There are three topsoil stockpiles within the permit area. Two of the stockpiles (TS-1 and TS-3) and a portion of the third stockpile (TS-2) do not drain to sedimentation ponds (see Exhibit 12-2). In order to demonstrate that these piles meet the intention of CDRMS Rule 4.05.2(3), SEDCAD+ analyses were conducted. These demonstrations are presented in Appendix 12-2, Small Area Exemption Demonstrations. The status of the stockpiles has not changed since, their construction in the late 1970's except for the establishment of vegetative cover. A similar demonstration was made by Yampa Mining Company for the topsoil stockpiles at the H-G Mine surface mine (approved CDRMS Permit C-80-003). Many of the parameters used in the H-G Mine demonstrations were borrowed for the Loadout small area exemption demonstrations based on similar seeding dates, rates, etc. Due to the shallow slopes, existing, well-established vegetation cover, and small i drainage areas none of the stockpiles exhibit a soil loss through sediment erosion. Consequently, the topsoil piles have been permitted as small area exemptions by CDRMS. 3 Revised 11./07 MR-16