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• 1.7 MUSKINGUM ROUTING PARAMETERS. K, X <br />• <br />• <br />The Muskingum Routing Parameters were also calculated using the SCS upland method. The hydraulic <br />lengths, drainage heights and associated slopes were determined from scaled drawings. The values <br />calculated between each structure and/or sub-watershed aze shown in the SEDCAD4 printouts. <br />1.8 CURVE NUMBER. CN <br />The runoff curve number is a factor relating the amount of rainfall to the amount of runoff for a given <br />azea. Curve numbers were jointly developed and agreed upon by the Division of Minerals and Geology <br />and Colowyo. The curve number for the topsoiled and seeded areas was based on a hydrologic soil group <br />B with no vegetation. Table 1 provides a summary of the curve numbers approved by DMG. Highlighted <br />values were used for the pond design evaluations. <br />TABLE 1 <br />DMG APPROVED SCS CURVE NUMBERS <br /> HYDROLOGIC PERCENT HYDROLOGIC CURVE <br />COVER COVER TYPE CONDITION COVER SOIL GROUP NUMBER <br />Disturbed Topsoil Bare N/A C 91 <br /> Stripped <br />Reclaimed Topsoiled and Bare N/A B 86 <br /> Seeded <br /> 1 to 2Year Fair---Good 85 B 61-58 <br /> Growth <br /> 1 to 2Year Fair N/A B 60 <br /> Growth <br /> 3+ Year Fair -Good 85 B 56-48 <br /> Growth <br /> 3+ Year Fair N/A B 52 <br /> Growth <br />Undisturbed M~ubtain Good 85 C 41 <br /> <br />Undisturbed Oak-Aspen Good 85 C 41 <br /> Sagebrush Good 85 C 47 <br /> Sagebrush Fair 50 C 63 <br />Sources: SCS TR-55 Urban Hydrology for Small Watersheds June, 1986 <br />SEDCAD+ Version 3.1 Users Manual <br />Agreement between DMG and Colowyo Hydrologists <br />1.9 BASE FLOW <br />Base flows were not used in any pond design calculations. Discharge of collected water from open pits <br />will not be pumped to any of the sediment ponds discussed in this section. <br />Exh. 7-20-3 Revision Date: 4/16/07 <br />Revision No.: PR-02 <br />