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-15- <br />16. Designs of sedimentation oonds must include an analysis of short circuiting <br />potential. The applicant inay use any established method of determining short <br />circuiting. (i.e., see "Deposits Planual" by ;•lard, Haan, and Tapp, page 73-81, <br />see also "Development of methods to improve performance of surface mine sediment <br />basins", EP.4 600/7-80-072, 1980, page 57-68 for examoles). If it is determined <br />that baffles will be needed in the ponds, the location and dimension of the <br />baffles must be shown on a map. Prevention of short circuiting is required <br />by section 4.05.6(6). <br />17. The application must contain a statement that commits to making quarterly <br />inspections of all ponds. A copy of this quarterly report must be forwarded <br />to the Division as required under section 4.05.6(11)(c). <br />18. For all ponds the application must stzte the height of the. embankments as <br />measured from the lo~•~est part of the channel to the bottom of the emergency <br />spillway. If any ponds measured are in er.cess of 10 feet they will have to <br />meet the applicable requirements of the State Engineer in accordance with <br />C.R.S. 37-87-105. <br />19. The application should include cross sections for each pond that verify <br />all elevations of the dam components. The minimum elevation of the top of the <br />settled embankment shall be 1.0 feet above the water surface in the pond v~ith <br />the emergency spillway flowing at desion depth. (see section 4.05.6(8)(d). <br />These elevations should be sho~•m on the cross sections. <br />20. Pond embankments to be constructed must he increased in size, a minimum of <br />5 percent over the design height to allow for settlement, unless it is demonstra- <br />ted to the Division that the material used and the design will encure against <br />all settlement. <br />21. The applicant must commit to certifying each sedimentation pond proposed to <br />be modified or constructed, and forwarding the certification to the Division <br />immediately following construction. These ponds must be certified by a quali- <br />fied registered professional engineer as required under section 4.05.6(7). <br />22. The application must commit to installinn markers in all ponds that clearly <br />indicate the 60 percent sediment storage elevation. <br />23. The following problems have been identified concerning the design of permanent <br />diversions: <br />a. For permanent diversions the Division requires that the ditch be designed <br />for unvegetated conditions with design velocities within the permissible limits <br />based on the type of channel lining. The ditch should then be redesigned for <br />capacity assuming maximum vegetative cover. This extra capacity is then added <br />to the ditch size. Our concern here is that it may take several years to establish <br />enough vegetation to achieve your design manning's 'n' value. In the meantime, <br />without vegetation, the ditch velocity will be much higher and scouring of the <br />channel may prevent the establishment of any vegetation. Since this ditch v+ill <br />be constructed after termination of mining, proper inspection and maintanence of <br />the ditch may not be feasible. tle therefore want to see the ditch designed as <br />maintanence free as possible. <br />