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PROTECTION OF THE HYDROLOGIC BALANCE <br />POND D <br />STORM EVENTS <br />10 YEAR 24 HOUR EVENT 1.8 INCHES <br />25 YEAR 24 HOUR EVENT 2.1 INCHES <br />100 YEAR 24 HOUR EVENT 2.6 INCHES <br />The information presented for the 25 -year event peak flow calculations is developed <br />with the use of SEDCAD. The output data from SEDCAD is on page Exh-8-207 & 208. <br />The upland run-off areas are shown on Map No. 20 in Volume II. The run-off <br />curve numbers are developed based upon vegetation and soil types. Vegetation <br />data are presented in Volume III Exhibit 5 and shown on Map 3 in Volume II. <br />Soils data are presented in Volume III Exhibit 7 and shown on Map 4 in Volume Il. <br />Ditches culverts and drainage plans are shown on Map 15-3. <br />CURVE NUMBERS <br />Coal Mine Waste <br />Table 2 -2d -Runoff curve numbers for and and semiarid rangelands <br />Cover Type - Herbaceous -mixture of grass, weeds and brush <br />Hydrologic Condition Poor <br />Soil Type D <br />Curve Number 90 <br />Disturbed -Poor <br />Table 2 -2d -Runoff curve numbers for and and semiarid rangelands <br />Cover Type - Herbaceous -mixture of grass, weeds and brush <br />Hydrologic Condition Poor <br />Soil Type - Loam C <br />Curve Number 87 <br />Disturbed -Good <br />Table 2 -2d -Runoff curve numbers for and and semiarid rangelands <br />Cover Type - Herbaceous -mixture of grass, weeds and brush <br />Hydrologic Condition Good <br />Soil Type - Loam C <br />Curve Number 74 <br />Disturbed -Fair <br />Table 2 -2d -Runoff curve numbers for and and semiarid rangelands <br />Cover Type - Herbaceous -mixture of grass, weeds and brush <br />Hydrologic Condition Fair <br />Soil Type - Loam C <br />Curve Number 81 <br />RUN-OFF VOLUME - - Pond D (NRCS/SCS Runoff Equation) <br />Precip Direct <br />Run-off <br />Area Acres Curve # Amount Run-off <br />Vol A -F <br />Disturbed -Poor 6.16 87 1.8 0.75 <br />0.39 <br />Disturbed -Good 1.60 74 1.8 0.26 <br />0.03 <br />1.70 <br />TR -98 Exh. 8-17 01/15 <br />