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/m~uary 2000 Cvpmr Tmndymrlr' Pond G Eralrmliou 3 <br />u <br />TABLE 1.1 <br />POND G WATERSHED CURVE NUMBERS <br />Area Cover Type Hydrologic Hydrologic Curve <br />Condition Condition Soil Grou Number <br />Reclaimed Reclamation Seed Mix Good (>70%) C 74 <br />Pre-Law Natural Reclaimed Fair (>50%) C 79 <br />Reclaimed Partial, Seeded <br />Dtsturbed None - - - C 90 <br />Dist.-Coal None NA B 8G <br />Stock Iles <br />3.0 SEDIMENTATION CALCULATIONS <br />The sediment calculations used to model Pond G was performed utilizing the SEDCAD4 Computer <br />c// Modeling Program developed by Civil Software Design. The SEDCAD3 Computer model calculates <br />annual sediment yield using the Revised Universal Soil Loss Equation (RUSLE). The input parameters <br />used in the sedimentation analyses are presented in the following sections. <br />3.1 Rainfall Factor, R <br />A rainfall factor of 30 was used for the TCC T`fine site. This factor is consistent with other recent <br />erosion analyses performed for the TCC Mine. <br />3.2 Soil Erodibility Factor, K <br />• The soil erodibility factors for the subject site were deterrnuted based on Sediment Yield <br />Demonstrations for bond release areas Blocks B Re C, (TeaaMatrix, 1995). From these reports an <br />average li factor of 0.22 was used for reclaimed and disturbed areas. Other Ik factors used are <br />smnmanzed in Table 1.2, Soil Erodibility Factor (Soil Conservation Servtce, 1983). <br />TABLE 1.2 <br />SOIL ERODIBILITY FACTOR <br />Soil Type Soil Texture Soil Erodibility <br />Factor <br />Mixture on Reclaimed <br />Surfaces Mix of sods 0.22 <br />Disturbed Areas Dlix of soils 0.22 <br />Pre-Law Spoil Dlix of soils ~ <br />Refuse Rough 0.1G <br />~~ <br />C: <br />ke~~~~,~ <br />~ ~~. G <br />Alontgomrrv Watson Alining Group " IGS S Union Boulevard, Swm 410' Lakewood, Colorado 8022H " (}U3) 7G}-5140 <br />