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APPENDIX M viii <br />~`' SMALL AREA EXEMPTION # 3 - SAfi 3 <br />I LOMA LOADOUT SURFACfi WATER CONTROLS <br />To control the runoff of water and sediment from the loadout, a <br />berm has been constructed on the south side of the area. In <br />accordance with applicable regulations, these calculations will show <br />that the sediment containment structures are capable of retaining <br />the entire volume of the design storm. <br />i ~J <br />The loadout is a strip of land up to 75 feet wide. The area that <br />drainage must be controlled is about 1300 feet long. The slope of <br />the area is about 2~ down from the track to the berm on the south <br />side. Water will be retained up to one foot high in the detention <br />area that is about 300 feet long. The berm retaining the water <br />will be at least 18 inches high and 36" wide at the base. <br />SPECIFICATIONS <br />Area = 97,500 sgft = 2.24 acres Ave Slope = 2~ <br />Soil Type = mixed use Group = C Veg. cover = 0~ <br />PEAK FLOW CALCULATIONS <br />1. From "Peak Flows In Colorado" Pio = 1.4" <br />2. Runoff: CN disturbed use CN = 87 <br />RUNOFF 10 yr Pe= 0.47" <br />3. For Area = 10 acre & Slope = 2% Slope Adj. Factor = 1.20 <br />4. Assume that Actual Area = Equivalent Area <br />Therefore, Actual area/Equivalent Area = 1.00 <br />5. For GN =87 and Area = 2.24 ac Op is about 2.8 cfs/inch <br />6. Equivalent discharge qio = 2.8#0.47"*1.20 = 1.58 cfs <br />7. The ACTUAL DISCRAAGE is: Q2o = 1.58 cfs <br />8. The VOLUME DISCHARGED is: Vio = 0.47"* 97,500ft/12 <br />Vio = 3,818 tuft <br />SIZE OF THE SEDIMENT TRAP <br />The detention area is triangular in cross section 1 foot high and <br />50 feet wide and 300 feet long. <br />The Volume of the Trap = 0.5 # base * height * length <br />Volume = 0.5 ~ 50' * 1' * 300' = 7,500 cubic feet <br />I~ <br />The trap has been designed to hold 0.69 ft. of sediment (3570 <br />tuft} as well as 3950 cubic feat of water. Sediment will be <br />cleaned from the trap when there is less than. one foot of <br />freeboard. <br />M(viii} - 2 11/11/91 <br />