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<br />for stability analysis. The steeper sloping section at Pond 013 is in an area of shallow <br />bedrock with a relatively low embankment height (6 feet). For these reasons we <br />believe the general model is adequate to reflect conditions at this site. <br />The stability analysis was performed using the program Slope/W"" developed <br />by Slope International, Ltd. We used modified Bishop analysis methods for circular <br />shaped failure surfaces. The models used 3 soil types including compacted clay in <br />the embankment, native clay soils and native sand soils. The strength of the clay <br />soils was conservatively selected as the residual strength value obtained from the <br />direct shear testing. The strength parameters (~ = 21 degrees, cohesion = 490 psf) <br />were based upon testing on a remolded clay sample. A friction angle of 30 degrees <br />with no cohesion was utilized for the sand soils. <br />Table B presents a summary of the stability analyses for each model analyzed. <br />• Colorado Division of Minerals and Geology (CDMG) requires a minimum factor of <br />safety of 1.3 for small sedimentation embankments (Regulation 4.05.6 (11) k). The <br />results of the stability analyses indicates factors of safety which significantly exceed <br />the 1.3 minimum required by regulation. <br /> <br />LORENCITO COAL COMPANY, LLO <br />SMALL SEDIMENTATION EMBANKMENTS <br />CTLR 26,559 <br />