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Kiowa Clay Mine, M-2007-009 <br />Response to Adequacy Comments <br />17 April 2007 <br />Page 7 <br />may be consolidated in one stockpile, as depicted on Revised Exhibit C-3. Clay <br />product will be stockpiled temporarily for hauling, as depicted also on Exhibit C-3, <br />averaging up to 60,000 cubic yards within the designated footprint. <br />The stockpiles will fluctuate with mining operations, and at most times will be less <br />than the maximum capacity due to concurrent placement of reclamation backfill. <br />The above quantities are the approximate maximum amount of material to be in <br />each stockpile through the active campaigns during the life of the-mine. <br />11. The applicant's reclamation plan map illustrates that the final reclamation <br />slopes at various points across the pit will be mined at slopes of 1h:1v. A <br />reclaimed slope of steeper than 3h:1 v will be difficult to stabilize and <br />revegetate and does not support the post-mining land use of rangeland. <br />Due to these constraints, the Division will not approve a reclaimed slope of <br />steeper than 3h:1 v. However, the Division will accept 3h:1 v slopes. Please <br />revise the reclamation plan and map accordingly. <br />The reclamation plan map has been revised to depict reclaimed slopes of 3h:1v. <br />The pit will be reclaimed to this slope gradient as a maximum. First, material will <br />either be moved from active mining areas imbedded with waste rock or taken <br />from overburden and topsoil stockpiles. In this process, slopes of up to 1h:1v will <br />be reduced to as near to 3h:1v as possible (or shallower). If there is not enough <br />material in the stockpile to achieve this slope, the applicant will cut and fill side <br />slopes to the point where the slope around the walls of the pit are at 3h;1v. In <br />other words, material will be taken from the top of the pit and placed at the base <br />of the slope (bottom of the pit) until a 3h:1v slope is achieved. <br />12. Slopes reclaimed on all sides of the pit will produce slopes greater <br />than 300 feet in length. Please state how the applicant intends to stabilize <br />the reclaimed land to control erosion on such long slopes. The applicant <br />will need to implement techniques to break down the slope length such as <br />including benches or berms. Please address accordingly. <br />The applicant's plan has always included the implementation of benches on <br />areas of the reclamation plan with protracted vertical change, notably the eastern <br />face of the mining area. As illustrated on the Revised Reclamation Plan <br />(Revised Exhibit F), even with backfill placed at 3:1, a bench is achieved with <br />every 20 foot vertical section. At 3:1, the horizontal distance under this slope <br />module is 60 feet. The hypotenuse of the slope module, being the longest <br />continuous slope on the site, is less than 64 feet. <br />The bench at the base of the typical slope prevents flows from concentrating, <br />accelerating with laminar flow, and attaining sufficient energy to have erosive <br />