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• compacted to 90 percent of maximum dry density (AASHTO Spec. T99-74) as required by Section <br />4.10.4. The refuse material has to dry out before it can be compacted properly. During the winter <br />months or at times when the material cannot be properly spread and compacted, the refuse material <br />may be temporarily stored on top of the refuse piles. Storage of refuse material in temporary piles <br />will not exceed 300,000 tons at any one time. <br />Tests shall be pertormed on the waste bank to ensure the minimum level of compaction is reached. <br />These tests shall be made in areas that represent the area being compacted. No test will be <br />performed during periods of rain, snowmelt or when the pile is unreasonably wet. Tests shall be <br />pertormed on a minimum of a monthly basis during the active compaction process of the refuse pile <br />construction. The tests shall be performed with a nuclear density meter. <br />During the early phase of mine permitting when no actual refuse material was available for testing, <br />the refuse strength and stability characteristics were assumed based on typical scenarios at other <br />sites. Once the actual refuse became available, Western Fuels-Utah (now BME) contracted Lincoln <br />DeVore Laboratories to develop a Proctor curve of the material. Nuclear density equipment was <br />purchased to verify required compaction results. It was found that the original assumptions were <br />quite conservative compared to the actual data. Based upon the actual data, the safety factor <br />exceeds 1.5 using a slope of 3(h):1(v). This factor will be significantly higher for a slope of 4(h):1(v) <br />and 5(h):1(v) as stipulated in the permit. A letter dated January 30, 1987 from Mike Weigand, Chief <br />Engineer at the Deserado Mine supporting the above findings is included as Illustration 42. <br />Additional strength tests on the refuse and stability analysis with a 4:1 slope were conducted by <br />Lincoln-DeVore, Inc. of Grand Junction. The static safety factor was calculated to confirm that it <br />exceeded 1.5. A letter from Lincoln-DeVore is included in Illustration 42A. In 2004 additional cores <br />of the refuse were tested for strength and stability. Based on the new data, Lincoln DeVore <br />concluded that the refuse piles would be adequately stable at 3(h): 1(v) and 200 feet in height. This <br />report is included in Illustration 426. <br />Most of the sedimentation ponds in the Refuse Disposal Area will be a combination dug-out or <br />in-situ and embankment type. This design was chosen because of layout and construction <br />considerations. Soils in this area are mostly Turley fine sandy loam and Moyerson silty-clay. The <br />Moyerson soils have properties suitable for dam embankment construction. Where ponds are <br />constructed in in-site materials not suitable for pond construction, suitable materials will be imported <br />from elsewhere within the Refuse Disposal Area and used to construct the required pond embank- <br />ments. The actual location of suitable construction materials will be determined during field <br />construction by a qualified Geotechnical Engineer or Technician and appropriate field laboratory <br />analysis. A detailed discussion of sediment pond design can be found in Section V-B. <br />Drainage and sediment control structures will be maintained so that they are stable and functional at <br />all times, until final bond release is approved. See Section IV.J.1 for the control systems. The <br />TR60 (7/2004) IV-18 <br />