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<br />POND M <br /> <br />Sediment Yield Calculations <br />Watershed Characteristics <br />Total Watershed Area: 174 ac. <br />Disturbed Area: 48 ac. <br />Antecedent Moisture Condition: II <br />Weighted Curve Number: 75 <br />10-yr, 24-hr Precipitation Event: 1.8 in. <br />10-yr, 24-hr Runoff Volume (Q): 4.20 ac-f t. <br />10-yr, 24-hr Peak Flow (gp): <br />Soil Erodibility Factor (K): <br />Length-Slope Factor (LS): <br />(hydraulic length = 5800 <br />LS = (L (72.6) 0'4 (65.41 <br />Crop Management Factor (c) _ <br />Support Practice Factor (P) _ <br />24.65 cfs <br />0.2 (clay loam soil) <br />ft., slope = 4Y,) <br />sing S + 4.56 sin S -h 0.065) = 2.03 <br />L.0 <br />1.0 <br />Modified Universal Soil Loss Equation <br />Y = 95 (Q gp) 0.56 K LS C P <br />= 518.4 tons x (2000 lbs/ton) / (60 lbs/cu. ft) / (43,560 sq. ft/ac) <br />= 0.397 ac-ft sediment <br />Required Sediment Storage Capacity <br />Volume = 10-yr, 24-hr sediment yield x (100/40) = 0.99 ac-f t. <br />(Pond will be cleaned out when 60~ full of sediment) i <br />Pond K Sediment Storage Capacity <br />Design Sediment Storage Volume: 0.96 ac-ft <br />As-built Sediment Storage Volume: 1.39 ac-ft <br />Required Sediment Storage Volume: 0.99 ac-ft <br />(Existing sediment storage capacity is adequate) <br />