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0 <br />• Analysis Sections <br />Excess Spoil Fills. The analysis section is shown on Fig C-1. The section is a <br />conservative model including a 10 degree slope (18 percent) of the basal clay and <br />bedrock layers with a 350-foot fill height. This configuration models worst case <br />conditions for fills 4 through 9. The model is also appropriate for the smaller excess <br />fills associated with contour mining. The model will be conservative for these smaller <br />fills. One exception is Fill 7-2. The base slope for this fill is about 13 degrees. A <br />specific section was analyzed for this fill (Fig. C-24). <br />Contour and Surtace Mine Fills. This section is shown on Fig. C-2. The flat <br />bedrock surtace in these areas results in an infinite slope condition when cohesion is <br />assumed to be zero, the height does affect stability results. The height was chosen as <br />250 feet to model the taller surface mine/area fill but also includes smaller contour area <br />fills. <br />•- Sedimentation Pond Embankments. This section is shown in Appendix D. The <br />section is 10 feet in height with 2.5:1 out-slopes. The section and analysis is considered <br />appropriate for the proposed sediment pond embankments. <br />Material Properties <br />Spoil strength and density is difficult to measure in laboratory or field tests due <br />to the large particle sizes. We selected bulk samples of excavated bedrock from road <br />cuts and test pits. Detailed laboratory test results of gradations and direct shear tests <br />are presented in Appendices B and E. <br />Direct shear tests were performed on four samples of "spoil" at various densities <br />relative to the maximum standard Proctor dry density (ASTM D 698). The results are <br />plotted on Fig C-3. The sampling method most likely under represents larger particle <br />LORENCITO COAL COMPANY, LLC <br />LORENCITO SURFACE MINE - PHASE I 9 <br />CTLR 32, 611 <br />