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• Sedimentation Pond No. 5 is designed to retain runoff from the mine access <br />road collection ditch, Collection Ditch CD-1, and facilities areas not <br />controlled by Pond No. 1. Facilities area runoff flows to a second mine <br />yard collection basin, and through a 24" CMP to the access road collection <br />ditch which flows into Pond 5. Pond 5 discharges to Magpie Creek at the <br />eastern edge of the permit area through NPDES discharge point 004. <br />Two (2) ponds, Sedimentation Ponds Nos. L-1 and L-2 are located in the <br />Southfield loadout area. These ponds have been designed and constructed <br />to retain runoff from a 10-year, 24-hour storm event. Both ponds are <br />almost totally incised with minimal embankment structures, and include <br />combination principal/emergency spillway structures designed to safely <br />pass peak flows resulting from the 25-year, 24-hour storm event. The <br />configuration and construction of the loadout area ponds are illustrated <br />by the Loadout Area Pond and Drainage Structure Design Maps, (Maps 26 and <br />27). <br />• Sedimentation Pond L-1 is designed to retain runoff from the area north <br />and east of the county road. Runoff from the east loadout area is <br />intercepted by a perimeter collection ditch and routed to Pond L-1. Pond <br />L-1 discharges through NPDES discharge point 001 to Chandler Creek. It <br />should be noted that runoff from the east loadout area topsoil stockpile <br />is contained by a closed containment ditch designed to retain runoff and <br />sediment resulting from a 10-year, 24-hour storm event. <br />Sedimentation Pond L-2 is designed to retain runoff from the area south <br />and west of the county road. Runoff from the west loadout area is <br />effectively contained by the railroad containment berm on the south edge <br />of this area and routed to Pond L-2 by a perimeter ditch. After retention <br />for sediment control, water impounded in Pond L-2 discharges to Oak Creek <br />through NPDES discharge point 002. <br />Designs for all sedimentation and other ponds have been prepared under the <br />• direct supervision and have been certified as appropriate by a qualified <br />registered professional engineer. None of the existing ponds meet the <br />criteria for designation as MSHA structures. <br />2.05.3-47 <br />