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IV.J Sedimentation and Drainage Control <br />• Sedimentation and drainage control systems utilized in the "D" Portal Area are shown on Maps 24, <br />25, 26, 27 and 34, Loadout Area are shown on Map 103a, in the Refuse Disposal Area are shown <br />on Maps 77, 77a, 78, 79 and 80, along the Conveyor and Slot Storage area on Maps 106 -113, in <br />the East Portal Area are shown on Map 89. These measures were in addition to mining and <br />reclamation procedures intended to protect the quality and quantity of existing surface and ground <br />water. Emergency spillways on all ponds are designed to safely pass the peak flow from a 25 -year, <br />24 -hour storm event (2.1 inches). Illustration 40 shows that the spillway design for Pond RR -1 can <br />pass 14.39 cfs when only 11.5 cfs is the maximum flow of runoff. Illustration 39 shows that the <br />ponds at the slot storage area (SS -1 and SS -2) have double the capacity of a 10 -year, 24 -hour <br />storm event. Since a 10 -year, 24 -hour event is 1.6 inches and a 100 -year event is 2.4 inches, a 3.2 <br />inch event is improbable. Therefore, no emergency spillways were designed into either SS -1 or <br />SS -2. Sedimentation and drainage control utilized for the B Seam ventilation shaft facility and <br />access is either shown on Map 151 or covered by the Small Area Exemptions in Illustration 44. <br />Sump dewatering holes SDH -2 and SDH -3 currently allow for the dewatering of the D -Seam <br />workings if needed. Ponds near these holes are designed to allow settling of suspended solids and <br />to allow aeration or other treatment prior to discharge. SDH -3 discharges by pipe to a pond next to <br />this site. SDH -2 can discharge by pipe to the SDH -3 pond or to the ponds between SDH -2 and <br />SDH -1. The SDH -2 /SDH -1 ponds discharge to the SDH -3 pond via gravity feed through a pipe. <br />• The primary spillway for SDH -3 pond was sized to handle 307 gpm of mine discharge. See Map <br />140 for spillway rating. Therefore, the inflow of these sources did not exceed the capacity of that <br />spillway. The SDH -3 pond discharges to an unnamed tributary to Red Wash through outfall #026 of <br />NPDES Permit No. CO0038024 (see Illustration 1-46). <br />The Deserado Mine is also allowed to remove water from the underground workings through the <br />portals to PP -2 pond. PP -2 pond is permitted to discharge through outfall #004 of the NPDES <br />Permit. <br />Other sump dewatering holes have been permitted, constructed and decommissioned through the <br />course of mining. Initially mine water was pumped out through the 'D' and East Portals. The East <br />Portals and associated treatment ponds have been reclaimed and removed from the NPDES <br />Permit. <br />SDH -1 was the first sump dewatering hole. It became obsolete once SDH -2 was constructed. <br />SDH -1 has since been plugged and reclaimed. The associated treatment ponds are still available <br />for use near SDH -2. <br />• Technical Revision #68 (05/2011) IV -37 <br />