PERMFILE130354

• Permit No: C1981071
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Section_Exhibit Name: EXHIBIT 29 DRAINAGE CONTROL
• Media Type: D
• Archive: No

Table TR91-31-2 (Cont.)
•
Assuae:
Ditch 5lidth = b = 10 ft
Side Slcpes = Z = ]:]
Rip-Rap D50 = 1.5 ft
South Side Ditch Design
~•
•
Q = AV = 1.49 R2/3 S1/2 A
N
Area 41 Fiil
Slope = Z5.'d
Area = ~bd zd2~
R = Ned. Radius = A
b+Zd Z` +1
P1 = 0.0395 (C5G)1/6 0.0395 (1.5)1/6 0.042
Q = 54.6 = 1.49 r lOd + (1)d2~ 2/3 [G.25] 1/Z [1 G;: + ld`]
0.042 L 'IG + 2d c
Calcula~e Q assuring flo:r depth = d = C.50 ft
Q = 35.470 5.250 2/3 [0.25 1/2 [5.25G~ = 55.5 cfs
[ll.ai]
Calcualted Q = 55.5 cfs > Req'd Q = 54.6 cfs
Velccity = Q/A = 55.5 / [0(0.5) + 1(0.5) 10.6 fps
Check riprap size
D50 = r,~ rS) O.li 2 = (10.~)(0.25)O.li Z = 1,12 ft.
~(SG-1)O.bo(5.3)J ~ (2.b-1)J.co (5.8)
Assured D50 = 1.5 ft so design D50 is ad=_quate.
Ex.. 29-18