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~. <br />~~ CRDA nO. 2 AND nO. 3 COLLECTION DITCH DESIGN <br />(Continued) <br />Ditch Design for CRDA No. 3 <br />Peak Flow: SE Ditch 35.1 CFS <br />NW Ditch 30.4 CFS <br />@S = 0.33 use d = 8" + 4" freeboard = 12" min. depth <br />@S = 0.03 use d = 15" + 4" freeboard = 19" min. depth <br />D5o = (VS°•~~/7.58)z x 12 = rip-rap size <br />V = Velocity = 35.1/6.8 = 5.2 fps <br />D50 = [5.2(0.33°•~~)/7.58]Z x 12 = 3.9" min. <br />Access Road Culvert <br />Flow Required: CRDA No. 2 East Collection Ditch = 28.6 CFS <br />CRDA No. 3 SE Collection Ditch = 35.1 CFS <br />CRDA No. 3 NW Collection Ditch = 30.4 CFS <br />Culvert Capacity: 30" CMP with square edge and 1' of cover <br />= 32 CFS <br />30" CMP with square edge and 18" of <br />cover 36 CFS (Handbook of Steel <br />Drainage and Highway Construction <br />Products, 1971, Figure 4-18 Inlet <br />~;! Control nomograph for corrugaged steel <br />pipe culverts) <br />30" CMP with 1' of cover needed for CRDA <br />No. 2 East ditch, 30" CMP with 1' of <br />cover needed for CRDA No. 3 NW ditch, <br />and 30" CMP with 18" of cover needed for <br />CRDA No. 3 SE ditch. <br />-~ Rev. 2/4/94 <br />CRDA2-7 <br />