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As a result of previous mining in the area of the proposed <br />out-of-pit spoil, rainfall and snowmelt will permeate the loose <br />spoil material down to the mined out Wadge floor and underclay. <br />Since the coal is likely to be more permeable than the underclay, <br />the water will flow down dip through the unmined Wadge seam. <br />Because of the permeability of the coal seam, significant wader <br />pressure is not anticipated to form in this area. No evidence has <br />been observed in the bank of Trout Creek to indicate the presence <br />of seepage above the Wadge coal seam. <br />Soil and Rock Properties <br />The soil and rock parameters selected for this stability <br />analysis were taken from the stability analysis prepared by Water, <br />Waste & Land, Inc. (WWL) in October, 1995 for the Moffat Area of <br />the Edna Mine. Section 4 "Stability Analysis" of WWL's 1985 <br />report explains the methods used to determine the soil properties. <br />WWL states in their report that the values selected for soil <br />properties for use in their stability analysis are conservative. <br />Since the greatest potential for shear failure exists at the <br />interface between the coal seam and underlying clay of interburden <br />shales, the coal was assumed to have the same strength parameters <br />as the underclay. As a result, the selected strength values for <br />the coal are much lower than that determined from laboratory <br />• testing. Low values were selected to conservatively represent the <br />potential shear resistance of the fractured rock. These <br />conservative soil properties were also used in this stability <br />analysis. <br />The soil properties defined by WWL and also used for this <br />stability analysis are as follows: <br />TABLE 1 <br />SOIL AND ROCK PROPERTIES <br />----------------------------------------------------------------------- <br />----------------------------------------------------------------------- <br />Effective Shear Strength <br />-------------------------------------------- <br />Saturated Friction <br />Strata Unit Weight Angle Cohesion <br />lpcf) (degrees) (psfl <br />----------------------------------------------------------------------- <br />----------------------------------------------------------------------- <br />Unconsolidated <br />Overburden Soil 125 32 0 <br />Overburden/Interburden <br />Sandstone/Shale 135 36 100 <br />Coal 95 27.3 0 <br />• Underclay 115 27.3 0 <br />----------------------------------------------------------------------- <br />----------------------------------------------------------------------- <br />4 <br />