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<br />Concrete trickle channel <br /> <br />Drop required = 3.0 ft. <br /> <br />PROCEDURE: <br /> <br />1. Determine maximum unit discharge. <br />q = VnYn = (6.0 fps)(4 ft) = 24 cfs/ft <br /> <br />2. Select the best combination of riprap classification <br />and chute slope. <br />Use Table 1 <br /> <br />Use the row for q = 25 cfs/ft <br />The following options are available: <br />a. Type M at 10:1 or flatter; Dr=1.75'; Drw=2.6' <br />b. Type H at 6:1 or flatter; Dr=2.6' ; Drw=3.25, <br />c. Type VH at 4:1 or flatter; Or=3.5' ; Drw=3.5' <br />The best combination of riprap classification and <br />slope will depend on many factors such as <br />availability and cost of the various riprap <br />classifications and right-of-way limitations. <br />Remember to consider bedding and filter cloth costs. <br />For the sake of this example select Type H riprap at <br />1{ . <br /> <br />a 7:1' slope. <br />3. Select length of downstream apron LB <br />From Table 1. LB = 20' <br />4. Determine crest wall elevation. <br /> <br />Use Table 2 <br /> <br />Bottom width = 50'. closest to 40' <br /> <br />Vn ~ 6 fps. halfway between 5 fps and 7 fps <br /> <br />8 <br />