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<br />Appendix M(vii) <br />Munger Canyon Mine <br />Hydrologic Calculations <br />Surface Water Controls <br />Coal Mine Waste Bank/Refuse Pile <br />STORM EVENTS <br />10 YEAR 24 HOUR EVENT <br />25 YEAR 24 HOUR EVENT <br />100 YEAR 24 HOUR EVENT <br />1.5 INCHES <br />1.9 INCHES <br />2.3 INCHES <br />The pond sizing calculations presented below are calculated based <br />on the manual -Procedures for Determining Peak Flows in <br />Colorado -published by the Soil Conservation Service dated <br />March 1984. <br />Ditch sizing calculations are prepared using SEDGAD °i 4 <br />The upland run-off areas are shown on Figure 2.2.6 Waste Disposal Site, <br />Plan. <br />u <br />The vegetation study for the mine is located in Volume I <br />Section 4.8 beginning on page 4-90. The vegetation type <br />in the foundation area of the refuse pile is Big Sagebrush <br />Shrubland. The vegetation type in the upland area is <br />Juniper Woodland, ref. Figure 4.8-1. <br />The major soil type in the foundation area of the refuse pile is <br />Rivra Loam Variant. The soil type in the upland area is <br />Torriorthents rock outcrop complex, ref Figure 4.7-1. <br />Disturbed Area <br />Herbaceous-Mixture of grass, weeds <br />Hydrologic Condition Poor <br />Soil Type -Rivera Loam Variant A <br />Curve Number 80 <br />Table 2-2d-Runoff curve numbers for arid and semiarid rangelands <br />I • <br />Refuse Pile <br />Herbaceous-Mixture of grass, weeds <br />Hydrologic Condition Poor <br />Soil Type - Refuse/Coal/Dirt including right-of-way D <br />Curve Number 89 <br />Table 2-2a-Runoff curve numbers for urban areas <br />Mu M(vii)-2 <br />6/02 <br />