2009-11-13_PERMIT FILE - C1982056 (3)

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• It should be noted that thicker lifts (> 12 inches) may be possible depending on the placement process and equipment utilized. This should be confirmed with field- testing during the initial construction of the pile and approved by this office. The moisture content of the fill materials should be monitored as the fill is placed. We recommend that the fill materials be stockpiled to allow the free water to drain prior to placement and compaction. If a considerable amount of fines are encountered in the fill materials, additional drying may have to occur prior to compaction of these materials. The moisture- density relationships (Proctor values) will vary depending on the gradation and material properties. The coal refuse fill materials should not be greater than 3 percent over the optimum moisture content at the time of placement. However, the required compaction may be achievable at 4 to 5 percent below the optimum moisture content with the more granular materials. Cover Material The cover layer will consist of 1.5 feet of soil material and 2.5 feet of suitable cover material for a total cover thickness of 4 feet. Cover material will be obtained by stripping the existing soil and upper weathered portion of the reclaimed spoils in the area of the proposed CRDA. The soil and cover materials will be stockpiled in the southern portion of the CRDA and placed on the finished slopes as each bench is completed. In addition, soil and cover material will be stripped from the east - facing slope of Area 1 of the • existing RDA and replaced on the west - facing slope of the same area. The cover materials should be placed in 8 to 12 inch lifts and compacted to a minimum of 92 percent of the maximum Standard Proctor density and within 3 percent of the optimum moisture content, as determined by ASTM D698. Particles (boulders) larger than 12 inches in diameter should be removed from the cover materials prior to placement. The boulders may be disposed of within the core of the CRDA, with MSHA approval, or disposed of off -site. Soil materials should be placed and revegetated as required by the regulations. The cover materials and soil will form the bench ditches; therefore, grading control of the cover and soil materials will be important to provide slope to the ditches as recommended by the Surface Water . Management Plan (Appendix A). The slope of the benches is noted on the CRDA Grading Plan (Figure C- 101). The following table summarizes cover and soil material movements. • Job Number: 08 -7915 NWCC, Inc. Page 10 Revised 10/12/09