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Exhibit6 <br />depth on final graded and ripped backfill prior to the placement of the A-horizon topsoil. <br />• Topsoil (A and/or E-horizons) will be directly hauled and placed to an average six-inch depth on <br />final graded and ripped AC andlor B-horizon materials. <br />Stockpiled Soil Replacement Plan. If final graded backfill is not available for direct haul topsoil and/or <br />subsoil placement, then Rio Grande will utilize the following replacement plan: <br />Subsoil (AC and/or B-horizons) will be hauled from designated subsoil stockpiles and placed to <br />an average 12-inch depth on final graded and ripped backfill prior to the placement of the A- <br />horizon topsoil. <br />• Topsoil (A and/or E-horizons) will be hauled from designated topsoil stockpiles and placed to an <br />average six-inch depth on final graded and ripped AC and/or B-horizon materials. <br />Topsoil and subsoil materials will be removed from the stockpiles when soil moisture conditions are <br />suitable to minimize soil compaction and pumping due to high soil moisture contents. Records detailing <br />topsoil and subsoil replacement depths and volumes will be maintained at the mine and compiled in the <br />Annual Reports. <br />SOIL AMENDMENTS <br />After final topsoil placement and grading, Rio Grande will collect and analyze topsoil samples to test for <br />soil fertility. A 500- by 500-foot grid will be superimposed on a map of the reclaimed area. Six soil <br />• samples will be collected within each 500 by 500-foot grid at a density of approximately one sample per <br />acre. The six samples will be collated, mixed and sent to the laboratory for analysis for the major nutrients <br />of nitrogen, phosphorous and potassium. The laboratory results will determine the nutrient amendments <br />necessary for establishment of native upland prairie. <br />If necessary, phosphorous and potassium nutrient amendments will be applied to the topsoiled areas after <br />final grading, but prior to ripping and surface roughening operations. One equipment pass with a ripper or <br />a disk will incorporate these nutrients to a sufficient depth. Due to the inherent fertility of properly <br />segregated and handled topsoil, nitrogen usually will not be required. <br />WATER HARVESTING & EROSION CONTROL MEASURES <br />A variety of water harvesting and conservation, and erosion control methods may be used to harvest and <br />conserve precipitation. Primary water harvesting, water conservation and erosion control methods and <br />practices include: contour furrowing, land imprinting, mulching (straw, native hay or hydro), cover <br />cropping, and placement of erosion control blankets. Descriptions of these methods and practices that can <br />be used to harvest and conserve water and control soil erosion are described below. <br />Surface Roughening <br />Surface roughening is the most important water harvesting and retention method that can be used in <br />reclaiming disturbed lands. Surface roughening that can be used at Red Rock mine includes contour <br />furrowing, contour drill seeding, cleat tracking and soil gouging. Surface roughening activities will be <br />performed on the contour whenever physically and operationally feasible. Construction along the contour <br />• is particularly critical for surface roughening with a linear configuration. Surface roughening operations <br />1180-Mine Permit Exhibits (Ju1.03.02)FINAL.doc E-4 <br />July 3, 2002 <br />