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Tests shall be performed on the waste bank to ensure the minimum level of compaction is reached. <br />These tests shall be made in areas which represent the area being compacted. No test will be <br />performed during periods of rain, snow melt or when the pile is unreasonably wet. Tests shall be <br />performed 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 />As the refuse bank grows higher, the edge will be sloped back at 4(h):1(v) to provide positive slope <br />stability and minimize slope erosion. <br />During the early phase of mine permitting when no actual refuse material was available for testing, the <br />refuse strength and stability characteristics were assumed based on typical scenarios at other sites. <br />Once the actual refuse became available, Western Fuels-Utah (now BME) contracted Lincoln DeVore <br />Laboratories to develop a Proctor curve of the material. Nuclear density equipment was purchased to <br />verify required compaction results. It was found that the original assumptions were quite conservative <br />compared to the actual data. Based upon the actual data, the safety factor exceeds 1.5 using a slope of <br />3(h):1(v). This factor will be significantly higher for a slope of 4(h):1(v) and 5(h):1(v) as stipulated in the <br />permit. A letter dated January 30, 1967 from Mike Weigand, Chief Engineer at the Deserado Mine <br />supporting the above findings is included as Illustration 42. Additional strength tests on the refuse and <br />stability analysis with a 4:1 slope were conducted by Lincoln-DeVore, Inc. of Grand Junction. The static <br />safety factor was calculated to confirm that it exceeded 1.5. A letter from Lincoln-DeVore is included in <br />Illustration 42A. <br />Most of the sedimentation ponds in the Refuse Disposal Area will be a combination dug-out or in-situ <br />and embankment type. This design was chosen because of layout and construction considerations. <br />Soils in this area are mostly Turley fine sandy loam and Moyerson silty clay. The Moyerson soils have <br />properties suitable for dam embankment construction. Where ponds are constructed in in-site materials <br />not suitable for pond construction, suitable materials will be imported from elsewhere within the Refuse <br />Disposal Area and used to construct the required pond embankments. The actual location of suitable <br />construction materials will be determined during field construction by a qualified Geotechnical Engineer <br />or Technician and appropriate field laboratory analysis. A detailed discussion of sediment pond design <br />can be found in Section V-B. <br />Drainage and sediment control structures will be maintained so that they are stable and functional at all <br />times, until final bond release is approved. See Section IV.J.1 for the control systems. The construction <br />of permanent ditch segments affected by final reclamation in refuse area 2l3 perimeter collection ditches <br />and refuse area 4 perimeter collection ditches will be delayed until final reclamation. Similarly, the <br />revegetation of collection ditches currently subject to deposition of coaly sediment and frequent <br />maintenance will be completed after the final revegetation of refuse piles are completed. Interim <br />measures wilt be taken to control sediment and ditch erosion. Such measures nay include some or alt <br />Mine Permit Renewal #3 (Rev. 8/99) IV-19 <br />