2011-11-28_PERMIT FILE - C1992081A (10)

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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 SEDCAD 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- year24 -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 #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 (TS -1, portion of TS -2, TS -3) within the Loadout area and six topsoil stockpiles (A, C, D, E, F and G) and one temporary waste stockpile (TWS) associated with the TAHR. The locations of these stockpiles are shown on Exhibit 9 -2, Soil Types & Topsoil Salvage Map (TA-HR Corridor) and Exhibit 12 -2, Surface Water Control Plan Map (Facility Area). In order to demonstrate that these piles meet the intention of Rule 4.05.2(3), SEDCAD+ analyses were conducted. These demonstrations and discussions are presented in Appendix 12 -2, Small Area Exemptions. The status of the stockpiles has not changed since their construction in the late 1970's and early 1980's except for the establishment of vegetative cover. Due to the shallow slopes, existing well established vegetative cover, and small 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 the CDRMS. PR -01 3 revised 10 /11