PERMFILE72086 - Laserfiche WebLink

Home Browse Search

Sub-area Top of Pile Face of Pile 1 7.1 TPY 529.2 TPY 2-3 6.8 TPY 1,872.4 TPY 4 10.5 TPY 1,368.4 TPY The layout of the waste banks and a typical cross section are presented in Maps 76, 77, 77A, 83 and 150. The last lift will not be compacted and its top 8-12" will be scarified to enhance a permeable interface for roots and water. V.B.6 Post Reclamation Sediment Control Sediment Pond DP-1 which collects runoff from the D Portal Area, will be removed during the removal of the Scullion Gulch diversion system when the D Portal Area is reclaimed. A series of three loose rock check dams have been constructed in the Scullion Gulch stream bed and its Vibutaries in the D Portal Area. The loose rock check dams and other sediment control measures are discussed in Section IV.J. The loose rock check dams are shown on Maps 43, 44 and 46. Cross-sections and details are shown on Map 43. The three loose rock check dams will be removed following successful reclamation and revegetation of the D-Portal area upstream. • The loose rock check dams will retard streamflow and thereby minimize erosion in the reclaimed Scullion Gulch stream bed. In addition, sediment deposition will occur behind the dams during runoff from small storms. It is anticipated that seepage through the rock dams will be partially blinded off by sediment deposition and thereby provide a minimal amount of settling volume for runoff from small storms. The total storage volume behind the three check dams is 1.74 acre-feet. The 3 year average sediment yield (per USLE) for the reclaimed D Portal Area is 0.51 acre-feet. The three year sediment yield for the total drainage area above and including the D Portal Area is 6.02 acre-feet. Thus, the reclaimed D Portal Area with the proposed contour furrowing and mulching would increase the sediment load in the Scullion Gulch at the D Portal Area by only 9.3% without the check dams being installed. See Illustration 22 for calculations. The reclaimed D Portal Area will be approximately 44 acres and the total area in Scullion Gulch which drains into the White River will be 7560 acres. Thus, the reclaimed D Portal Area will be only 0.6% of the total area draining into the White River. Since the reclaimed area will be very small in comparison to the total drainage area, the overall quality of the water reaching the White River from Scullion Gulch during a runoff event will not be significantly affected, An alternative to the use of contour furrowing, mulching, jute netting, and loose rock check dams would be the construction of a large sediment pond across Scullion Gulch downstream from the D (Permit Renewal #3, 8199) V-16