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• waste coal currently being placed in the RDA. The results of the field and laboratory investigations are <br />presented herein. <br />This report has been prepared to summarize the data obtained and to present our conclusions and <br />recommendations based on the characteristics of the processed waste coal materials being placed in the <br />RDA and the construction techniques presently being used at the site. <br />PROPOSED CONSTRUCTION <br />It is our understanding that the RDA is presently designed for a coal waste capacity on the order of 3 <br />million cubic yazds. When completed the RDA will be approximately 3,500 feet in length and <br />approximately 500 to 800 feet in width. A maximum slope height of approximately 125 feet is proposed <br />along dte eastern edge of [he RDA. The slopes situated along the eastern edge of the RDA will be <br />constructed to a 2.8 (horizontal) to 1 (vertical) configuration. However, several benches will be <br />constructed, which will result in an average slope configuration of 3 (horizontal) to 1 (vertical). The <br />benches will be approximately 20 fee[ in width and will slope back away from the finished slope at <br />0.5 %. The benches will be constructed at a maximum vertical interval of 50 feet. <br />• SITE CONDPCIONS <br />At the time of this investigation, the contractor had nearly completed the fill placement for the first bench <br />of the RDA, with the exception of the north end of the RDA, and had stared temporazily stockpiling the <br />waste coal materials in the southern half of the RDA. Based on our discussions with the contractor, Bud <br />Bower of Bower Brothers Construction, they have halted the fill operations for the year and aze now <br />stockpiling the waste coal materials being generated by the prep plant along the western side of the RDA. <br />This is due to the fact that the cold weather conditions prohibit the spreading and compaction of the <br />materials per the plan. <br />It should be noted that all of the topsoil materials had been removed from the entire RDA prior [o the <br />placement of any waste coal materials and these areas were observed by our firm. >n addition, our firm <br />observed and inspected the toe drain and buttress fill placed along the eastern edge of the RDA, as i[ was <br />constructed. Based on our observations and inspections, it appeared that the toe drain and buttress were <br />constructed in general accordance with the typical RDA details outlined in the repott prepazed by <br />CTUThompson, Inc. It should also be noted that our firm has been completing the compaction testing <br />on the waste coal materials as [hey are being placed in the RDA. <br /> <br />Job No. 97-7216 Northwest Coloredo Consultanu, Inc. Page 2 <br />