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CALCI[ILATIONS <br />• The following soil information was obtained from a representative soil sample sent to Trautner <br />Geotech in Durango, Colorado: <br />Internal Friction Angle (~) = 33° <br />Soil Cohesion (c) = 120 pcf <br />Soil Density (Y) = 115 pcf <br />r~ <br />L <br />I • <br />Sediment Pond Factor of Safety Chart Calculations fDrv & Saturated Conditions) <br />Embankment Height (H) =11 feet <br />Slope Angle = 26.5° (2H:1 V) or 18.43° (3H:1 V) <br />Factor ofSafety = F <br />Using the above information and using Circular Failure Chart Number 1 (Dry Conditions) the <br />value for c/YH Tan ~ is calculated. Using this value you enter the chart and go to the <br />appropriate slope angle 26.5° or 18.43°. From the y-axis the value of Tan ~/F is read. From this <br />value the Factor of Safety (F) is calculated. The same procedure is followed for the saturated <br />condition except Circular Failure Chart Number 5 is used. <br />Factor of Safety <br />Condition c/YHTancp Tanrk/F 2:1) Tan~/F 3:1 F (2:1) F (3:1) <br />Dry .1461 .2fi .20 2.32 3.24 j <br />Saturated .1461 .4l .31 1.58 2.09 <br />Circulaz Failure Chart Number 1 (Dry Conditions) and Circular Failure Chart Number 5 <br />(Saturated Conditions) are shown on the next two pages. <br />NNional King Coal LLC. <br />King Mine ![ <br />Aprii 2006 <br />