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SNOWCAP COAL COMPANY <br />• APPROXIMATE ORIGINAL CONTOUR VARIANCE <br />Watershed Analysis -Rule 2.06.5(2)(d) <br />Rule 2.06.5(2)(d) requires a demonstration that the watershed of the reclaimed surface <br />facilities will be improved. The watershed will be considered improved if; (i) there will be a <br />reduction in the amount of total suspended solids discharged to the surface waters from <br />the area as compared to such discharges prior to mining; and (ii) the total volume of flows <br />from the permit area, during every season of the year, will not vary in a way that adversely <br />affects the ecology of any surface water or any existing or planned use of surface or <br />ground water and; (iii) the appropriate State environmental agencies approve the plan. <br />Rule 2.06.5(2)(d)(il <br />The Universal Soil Loss Equation will be used to compare the soil loss from the'aaproved' <br />post-mining contour map (Exhibit 6C) to the'prooosed' post-mining contour map including <br />the alternate land use areas (Exhibit 6C) to determine 'rf the 'proposed' configuration will <br />reduce the amount of total suspended solids discharged to the surface waters as <br />compared to the 'approved' discharges shown on Exhibit 6C in the permit. <br />The following sediment volume calculation is prepared in accordance with U. S. <br />• Department of Agriculture, Technical Notes, Agronomy Note #50, dated January, 1977. <br />USING THE UNIVERSAL SOIL LOSS EQUATION (USLE) <br />A = R*K*L*S*C*P <br />A is the soil loss in Tons/Acre/Year <br />R =rainfall factor <br />The rainfall factor is derived from the State map (Figure 1) revised April 1980. A factor of <br />20 will be used for both the 'approved' and 'proposed' configuration of the facilities. <br />K =soil erodibility factor <br />The soil map, Exhibit 23 shows the soils type as 66 - "Torriorthents, Warm-Rock Outcrop" <br />and 4 -- "Bari Clapper Complex". Generally the soil samples for this and otherdisturbance <br />areas indicates the soil is sandy to silty loam (Tab Section 9) which equates to a "B" soil <br />group. Clapper has a published soil group of "B" in Table B-1 of Peak Flows in Colorado. <br />The K factor for generally used and accepted for Road Side South (RSS) USLE is 0.25 and <br />will be used for the 'approved' and `proposed' configuration for the vegetated areas. A K <br />factor of 0.0 will be used for concrete and asphalt, and a K factor of 0.10 will be used for <br />• gravel surfaces for the `proposed' configuration. <br />PR-03 A14-9-1 06107 <br />