PERMFILE136301

• Permit No: C1981071
• IBM Index Class Name: Permit File
• Doc Date: 12/11/2001
• Doc Name: pg 780-1 to 780-140
• Section_Exhibit Name: PART 780 RECLAMATION & OPERATIONS PLAN
• Media Type: D
• Archive: No

TABLE MR 87-17
DIVERSION DITCH DESIGN
Slope
Basin Adjust.
Basin Area CN QP Runoff Slope Factor Q1n
(Acres) (cfs/in) (in) (%) `Cfs)
31-1 121 82 113 0.52 14 0.96 56
Peak Flow = 56 cfs for Basin 31-1
Design for V Ditch
Side Slopes (z) = 1:1
Ditch Slope (s) = 2.0%
Mannings N (n) = 0.035
Q = AV = 1.49 R2J3 S1l2 A
n
Q = 56 = 1.49 z d 1 2/3 (S)1/2 (zd2)
0.035 2 z2 +1J
~ Q = 56 = 42.57 / d \ 2/3 (0.14) d2
(\2.63
9.40 r~ 2/3 d2
2.8
d = 3.0
Flow Depth = 3.0 FT
Freeboard = 1.0 FT
Ditch Depth = 4.0 FT
Velocity
Q=AV
V = Q/A
V = 56/zd2
= 56/(3.0)2(1)
= 6.22 fps
•
780-57(b) 04/10/87