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1. A series of sedimentation ponds; <br />2. Soil surface mechanical manipulation measures that include contour <br />furrowing, chisel plowing, etc. <br />3. Topographic manipulations that include recontouring or reshaping of <br />graded material in a manner that minimizes the potential for soil erosion; <br />4. Surface protection measures that include surface stabilizers such as <br />temporary cover crop, permanent vegetation covers, or geotextile fabrics, <br />etc.; <br />5. Linear detention and filtering structures that include filter fence, straw bale <br />barrier, brush barrier, and filter berms; <br />6. Measures used in conjunction with overland conveyances including check <br />dams, sediment traps, and water level spreaders; <br />7. Vegetative filters, temporary cover crops, reestablished permanent <br />vegetation covers, etc. <br />All surface mining operations will be conducted to achieve the effluent limitations of <br />4.05.2(7) for all mixed drainage when it leaves the permit area. Sedimentation ponds or <br />impoundments will be constructed before creating new disturbances, unless approved <br />drainage diversions or other surface water control structures are installed. <br />WFC retained Arcadis U.S., Inc. to assist in the design of sediment and water control <br />facilities such as sediment ponds and ditches. A copy of the Arcadis report is attached <br />with this section as Appendix 2.05.3(4) -1. As -Built documents are included with this <br />section and begin with Appendix 2.05.3(4) -6 <br />Collection Ditches, Culverts and Diversion Design Parameters <br />The main collection ditches in the proposed permit area are the NHN -001 East and <br />West, The NHN -002 North and South, and the NHN -003 North and South Ditches. <br />These ditches are used to transport runoff into Sedimentation Ponds NHN -001, NHN - <br />002 and NHN -003 for treatment in accordance with the requirements of applicable <br />regulations. The location and drainage area of these ditches can be found on Figure 1 <br />of the Arcadis report. Culvert designs are presented in Appendix 2.05.3(4) -2. Culverts <br />were designed using SedCAD software. Subwatershed areas were created for each of <br />the areas flowing to the individual culverts. In general a curve number of 91 was used in <br />the SedCAD program for all of the areas that were disturbed. Three culverts were <br />designed using different curve numbers. Two of the culverts, C -6A and C -613 were <br />designed using a curve number of 79. This use was justified as the watersheds SW -MD <br />and SW -MD2 consist of pasture or rangeland with fair hydrologic conditions and <br />hydrologic soil group C as shown in the SedCAD software and are not a part of the <br />mine disturbance area. The third culvert, C -12, was assigned a curve number of 89 <br />which is compatible with its watershed area, SW2 -D, which is a gravel road. <br />All ditches were designed in accordance with the applicable regulations in 4.05.3. <br />Diversions will be designed, constructed, and maintained in a manner which prevents <br />additional contributions of suspended solids to stream flow and to runoff outside the <br />Section 2.05.3(4) Page 2 November 2012 <br />MR- 02%7 -01 <br />�pp(_A44 <br />03 *v Oo 1 3 <br />