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Jarrnnry?000 C7pmr Tuenr7mde'PonAB Eualua/ran 3 <br />C' <br /> <br /> <br />• / <br />• <br />TABLE 1.1 <br />POND B ~GATERSHED CURVE NUMBERS <br />Area Cover Type Hydrologic Hvdrologic Curve <br />Condition Condition Soil Grou Number <br />Reclaimed Reclamation Seed Mix Good (>70%) C 74 <br />Pre-Law Natural Reclaimed Fair (>SOio) C 79 <br />Reclaimed Partial, Seeded <br />Disturbed None - - - C 90 <br />Disc.-Coal None NA B SG <br />Stock Iles <br />3.0 SEDIMENTATION CALCULATIONS <br />The sediment calculations used to model Ponds B and G were performed utilizing the SEDCAD4 <br />Computer Modeling Program developed by Civil Sofhvare Design. The SEDCAD4 Computer model <br />calculates annual sediment yield using the Revised Universal Soil Loss Equation (RUBLE). The input <br />parameters used in the sedimentation analyses are presented in the followmg sections. <br />3.1 Rainfall Factor, R <br />A rainfall factor of 30 was used for the TCC Mine site. This factor is consrstent 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 determined based on Sediment Yield <br />Demonstrations for bond release areas Blocks B & C, (TerraMauix, 1995). From these reports an <br />average K factor of 022 was used for reclaimed and disturbed areas. Other K factors used are <br />summarized in Table L2, Soil Erodibility Factor (Soil Conservation Service, 1983). <br />TABLE 1.2 <br />SOIL ERODIBILITY FACTOR <br />Soil Type Soil Texture Soil Erodibility <br />Factor <br />Dlixture on Reclaimed <br />Surfaces blix of soils 0 22 <br />Disturbed Areas Mix of soils 0.22 <br />Pre-Law Spoil Mix of soils 0.22 <br />Refuse Rough 0.16 <br />h(on[gomery \\'arson MirunG Group' IGS J. Union Boulevard, Suite 410 ' LaAewood, Colorado 80228' (303) 7G3-5130 <br />