1987-12-01_PERMIT FILE - C1981017 (110)

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4. SEDIMENT YIELDS a. Soil Losses derived by Universal Soil Loss Equation Soil Loss A = RQLS CP tons/acre Ref: SCS Tech Note 50 - F A C T 0 R S - Drainage Soil Length Control Annual Sediment Area Rainfall Erodability Slope Practice Losses-Factor A R K LS CPtons/acre AF/acre I 1 / Pad 1 40 .42 3.50 1 58.8 0.0390 Pad 2 40 .40 0.66 1 10.5 0.0069 Pad 3 40 .40 0.43 1 6.9 0.0045 Pad 4 40 .40 0.28 1 4.5 0.0030 z Density 70 pcf Z ton/acre * 1 * acre * 2000 Zbs = 0.000656 ac/ft 70 pcf 43560 ft 1 ton acre b. Soil Erodability Observed general soil conditions as follows: All Pad Areas / Slopes 1) % Gravelly to stoney rock fragment 30 to 80 30 to 50% 2) % Clay silt-fine sand 50 60% 3) % Sand 20 20% 4) % Organic matte 0 1% 5) Soil Structure 4 1 to 2% 6) Permeability 6 3 to 4% 7) Soil Erodability 0.40 0.60� C. Estimated Annual Yield of Sediment Delivered To Pends i Sediment Estimated Drainage Unit Sediment Delivery i Annual Sediment Yield Area Area Loss-Factor A Ratio (acres) (acre feet/acre) *1 ac.ft/acre iTotal ac.ft ft� Pad 1 2.38 0.0390 0.8 0.0312 0.074 3220 Pad 2 0.75 0.0069 0.8 , 0.0055 0.004 174 Pad 3 0.44 0.0045 0.7 10.0032 0.0014 61 Pad 4 1.14 0.0030 0.7 0.0021 0.0024 105 TOTAL 0.0818 a c. f_t y_ *1 Estimated Sediment Delivery Patio for Bare Ground Steep Slopes - 90% of Gross Erosion is Sediment Yield Flat Pads - 70% of Gross Erosion is Sediment Yield -4- 38