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. emission permit requirements, HGTI will reclaim approximately 2.8 acres of previously <br />disturbed area that drains to the Truck Loop Pond. Coal refuse located in the excess <br />stockpile area will be removed (see Attachment 12-1, Exhibit 12-2 [Revision 5, TR-04 <br />Incidental Permit Boundary Change, dated 8/99] foz the location o£ the excess coal stockpile <br />area), and the area will be topsoiled and reseeded with seed mix #1 (see Tab 20, <br />Revegetation Plan). These reclamation activities will reduce the disturbance area by <br />approximately 57 percent and consequently, the amount of runoff to the pond generated by the <br />10-year, 29-hour storm event. <br />Rail Loop Pond <br />Appendix 12-1 also contains a SELY;AD 4 modeling demonstration that shows the existing <br />configuration (1.84 acre-feet of storage) is sufficient to detain runoff from the 10-year, <br />29-hour storm event and, that the as-built pond configuration meets the requirements of <br />Rules 4.05.6 and 9.05.9. <br />As part of the 2,000,000 ton per year unloading system construction, to satisfy air emission <br />permit requirements, HGTI will reclaim approximately 9.7 acres of previously disturbed area <br />I ~ that drains to the Rail Loop Pond. The area will be backfilled, graded, topsoiled and <br />reseeded with seed mix No. 1 (see Tab 20, Revegetation Plan). The reclamation will reduce <br />the disturbance area by approximately 34 percent and consequently, the amount of runoff to <br />the pond generated by the 10-year, 29-hour storm event. <br />Small Area Exemptions <br />Topsoil Stockpile: There are three topsoil stockpiles within the permit area. Two of the <br />stockpiles (TS-1 and TS-3) and a portion of the third stockpile (TS-2) do not drain to <br />sedimentation ponds (see Exhibit 12-2). In order to demonstrate that these piles meet the <br />intention of CDMG Rula 4.05.2(3), SEDCAD+ analyses were conducted. These demonstrations are <br />presented in Appendix 12-2, Small Area Exemption Demonstrations. <br />The status of the stockpiles has not changed since their construction in the late 1970's <br />except for the establishment of vegetative cover, A similar demonstration was made by Yampa <br />Mining Company for the topsoil stockpiles at the H-G Mine surface mine (approved CDMG Permit <br />C-80-003). Many of the parameters used in the H-G Mine demonstrations were borrowed for the <br />Loadout small area exemption demonstrations based on similar seeding dates, rates, etc. Due <br />. to the shallow slopes, existing, well-established vegetation cover, and small drainage areas <br />none of the stockpiles exhibit a soil loss through sediment erosion. Consequently, the <br />topsoil piles have been permitted as small area exemptions by CDMG. <br />TR-07 3 Revised 06/06 <br />