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U <br />West Fbrtal Containment Area Sizing <br />Containment Areas 1 and 2 <br />Containment Area 1 <br />Runoff Volume <br />Area = 10.3 acres <br />CN=60 <br />10 year-24 hour = 2.9 inches <br />1.25 inches x 10.3 acres x 1 foot/12 inches = 1.07 acre-feet <br />Sediment Voliane 3 Years <br />A=RKLSCSD <br />A = (75)(.24)(7)(.16)(.39)(.65) = 5.11 tons/year/acre <br />5.11 tons/year/acre x 2000 lbs x 1 ft3/120.5 lbs x 1 acre/43560 x .6 x <br />3 years = .0035 ao-ft/acre x 10.3 acres = .04 ao-ft (nominal) <br />Current capac~ty = 150 ft x 150 ft x 4 ft = 90,000 ft3 = 90,000 ft3/ <br />43560 ft /acre-foot = 2.07 acre-ft; existing containment can <br />handle runoff. <br /> <br />Containment Area 2 <br />Runoff Volume <br />Area = 2.9 acres <br />CN=80 <br />10 year-24 hour = 2.9 inches <br />runoff = 1.25 inches <br />1.25 inches x 2.9 acres x 1 <br />Sediment Voliane 3 years <br />A=RKLSCSp <br />foot/12 inches = 0.30 acre-feet <br />A = (75)(.24)(.38)(.02)(.39)(.65) _ ..03 tons/year/acre <br />.03 tons/year/acre x 2C'?J lbs x i ft3/120.5 lbs :: J ~+=re/43560 x .6 x <br />3 years = .0000206 acre-it/acre x 2.9 acres = .00006 ao-ft <br />(nominal) <br />Containment Ar3ea 2 sizing = 114 ft x 114 ft x 2 ft = 25,992 ft3/ <br />43560 ft /acre-foot = 0.6 acre-feet. <br />• <br />