1992-07-01_REVISION - C1991078

• Permit No: C1991078
• IBM Index Class Name: Revision
• Doc Date: 7/1/1992
• Doc Name: Joe Dudash Review Information
• Type & Sequence: PR1
• Media Type: D
• Archive: No

Collection Ditches
Collection Ditch CD-3E will be a triangular channel 0.800
feet deep with 2h: ly side slopes. With a freeboar , f 3'
the total depth of the collection ditch is . 100 ee .
The flow velocity is slow enough that erosion wi be /P2
problem.
Collection Ditch CD-1W
Flow In a Triangular Channel
DEPTH D 0.900 FEET
SLOPE S 0.020 EXPRESS AS DECIMAL
n N 0.035 EXPRESS AS DECIMAL
Mannings ��N 2.000 SLOPE = X: 1
SIDE SLOPE X Y
AREA=(W*D)+(X*D^2)= ✓ 8 1.62 ✓ FEET-2
WETTED PERIMETER=(W)+2 ( (XD^2+D^2) ) ^ . 5 3.58 4 . 02 ✓ FEET
R=AREA/WETTED PERMITER ✓ .34 0.40✓
V=(1.49/N) * (R^ . 667) * (S^ . 5)= ✓3, o5 3 .28✓FEET/SEC
3_9 v 5.3 2 f CFS
Q = A X V =
Q REQUIRED 4 .93
Collection Ditch CD-lW will be a triangular channel 0.900
feet deep with 2h: ly side slopes. With a freeboard of 0. 3 '
the total depth of the collection ditch is 1.200 feet.
The flow velocity is slow enough that erosion will not be a
problem.
The ditches will be vegetated with the seed mix
that will be used on the topsoil stockpiles. According to
Table 4-8 - Maximum Permissible Velocities in Vegetal-lined
Channels - in the Handbook of Steel Drainage & Highway
Construction Products - the allowable flow velocity for
a grass mixture lined channel is 4 to 5 feet per second.
Collection ditch CD-1E has a calculated velocity which is
slightly over the allowable veloctiy so the ditch will be
monitored for erosion an maintenance will be performed as
necessary.
Summary of Ditch Sizes:
Ditches are all V-Ditches with 2H: 1V Side Slopes
Depth Freeboard Total Depth
Ditch CD-3E 0.80 0.30 1. 10
Ditch CD-2E 1.00 0.30 1. 30
Ditch CD-1E 1.40 0.30 1.70
Ditch CD-1W 0.90 0.30 1.20
9-32 July 1992