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Revised 7/8/82 <br />Calculations of Flow of 10-Year, 24-Hour <br />• Precipitation Event Through Sediment Control Structure <br />• Assumptions <br />- Estimate runoff for 10-year, 24-hour event <br />- Treat drainage basin as a single unit <br />- Effect of diversion ditches on flow into sediment is negligible <br />- Sediment pond is empty when runoff begins <br />• Methodology <br />- Estimate runoff by methods described in "Procedures for <br />Determining Peak Flows in Colorado," SCS, USDA, 1980 <br />• - Estimate inflow hydrograph based on methods described in <br />Hydrology & Sedimentology of Surface Mined Lands, C. T. Haan, <br />B. J. Barfield, 1979. <br />- Estimate sediment yield for disturbed area by Universal Soils <br />Loss equation <br />- Estimate outflow by equal increments of time, head and inflow <br />considerations <br />• Conclusions <br />- Sediment pond contains flow from a 10-year, 24-hour <br />precipitation event <br />• - Sediment pond contains .21 acre-feet of volume for use as <br />sediment storage <br />