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2.05.3 Sedimentation Ponds -Mine Site Four sedimentation dams were constructed from September, 1978, to June, 1979, between elevation 6,775 feet and elevation 6,600 feet of the mine Permit area. They are located directly south of the mine site immediately downstream from the reclaimed and west ridge waste disposal sites in the S''/:SE'hSE'h, Section 24 and the NE'hSE'/,, SE'hNE'/, (North of Steven's Gulch road), Section 25, T.13.S., R.92.W., 6th P.M. (see Map 8-1). These ponds were designed and constructed with the input of Chuck Leaf P.E., a consulting civil engineer and hydrologist, and after consultation and approval of the Office of Surface Mining, the U.S. Geological Survey and the State of Colorado Mined Land Reclamation Board. See Map No. 8A-l, Construction Specifications for Sedimentation Ponds, and Pond Construction Certifications in the Ponds, Lnpoundments, and Dams Appendix in Volume 8A. The ponds conform to 4.05.2, .5, .6, .7, and .17. The dams containing the sedimentation ponds aze constructed using conventional steel bin wall construction. It utilizes a reinforced concrete spillway and spillway apron. Plans, specifications, and "as constructed" surveys are as shown in the Ponds, Impoundments, and Dams Appendix in Volume 8A • In 1982, GeoHydro Consulting, Inc. of Denver, Colorado, was retained to complete the Phase III stability analysis, designing the waste rock disposal facilities. Included was the design of an additional sedimentation pond. The waste area sedimentation pond was constructed in series with sedimentation ponds 3 and 4 and was designed to hold increased sediment loads due to the addition of disturbed area and runoff from additional areas. The earthen embanlanent of the pond was constructed with on-site colluvial soils and compacted to a maximum dry density of at least 95%, as determined by the American Association of State Highways and Transportation Officials SpeciScation T99-74. Refer to the Waste Disposal Appendix in Volume 6A for specific information on the waste area sedimentation pond design and construction. In order to divert runoff from the two topsoil stockpiles located to the south of the West Ridge Disposal Area, two collection ditches were constructed. The ditches direct flow into Pond 3. The design for these ditches can be found in Volume 8, Surface Drainage Appendix of the permit. The ditches will have 0.3" freeboazd. The original culvert G was removed so that the upland flow is directed towazds culvert G'. The design for this culvert can be found in Volume 8, Surface Drainage Appendix of the permit document. The design for both the above referenced ditches and culvert were provided by Water Engineering Technology, Inc. The storage capacities of the sedimentation ponds aze set forth in Table 2.05-2 below: • TR-32 - 27 - 9/99 2/ 8/0 0