SW6210601_Design Calculations (Ditch Table)_20211008

CALCULATIONS
sheet only set up to handle Tc from 5 min to 30 min
A. Flow velocity < 2.0 fps when discharging to wetlands
Storm Event
Rainfall Intensity
5-min
10-min
15-min
30-min
10-yr
7.88
5.63
5.32
3.85
25-yr
8.87
7.06
5.97
4.42
50-yr
1 9.53
7.60
6.41
4.83
100-yr
1 10.20
8.10
6.83
5.23
B. Channel slope < 5.0% for curb outlet swales
Drainage
Impervious
Grassed
Tc
Storm
Rainfall
Ditch No.
C
Kerby
Kirpich
Intensity
Q (cfs)
Area (ac)
Area (ac)
Area (ac)
Event (yr)
Total Tc
Tc Used
(in/hr)
L (ft)
n
s
Tov
L (ft)
S
Tch
1
1.06
0.08
0.98
0.35
412.0
0.40
0.009
27.17
252.0
0.005
4.24
31.41
30
10-yr
3.85
1.43
2
3.32
0.26
3.06
0.35
303.0
0.40
0.018
20.00
362.0
0.005
5.60
25.60
30
10-yr
3.85
4.47
3
2.84
0.22
2.62
0.35
472.0
0.40
0.010
28.24
125.0
0.010
1.89
30.13
30
10-yr
3.85
3.83
4
1.97
0.61
1.36
0.50
252.0
0.40
0.020
17.90
411.0
0.005
6.18
24.08
30
10-yr
3.85
3.79
5
0.72
0.17
0.55
0.45
n/a
471.0
0.008
5.87
5.87
5
10-yr
7.88
2.55
6
4.30
0.99
3.31
0.45
374.0
0.40
0.009
25.97
657.0
0.018
5.41
31.38
30
10-yr
3.85
7.45
7
1.39
0.43
0.96
0.50
187.0
0.40
0.010
18.33
235.0
0.005
4.02
22.34
15
10-yr
5.32
3.71
8
5.09
0.78
4.31
0.40
520.0
0.40
0.010
29.55
210.0
0.005
3.68
33.23
30
10-yr
3.85
7.84
9
2.65
0.61
2.04
0.45
571.0
0.40
0.010
30.87
240.0
0.005
4.08
34.95
30
10-yr
3.85
4.60
10
1.49
0.34
1.15
0.45
316.0
0.40
0.110
13.33
230.0
0.005
3.95
17.28
15
10-yr
5.32
3.57
11
1.95
0.30
1.65
0.40
365.0
0.40
0.018
21.82
200.0
0.005
3.55
25.36
30
10-yr
3.85
3.01
12
1.65
0.38
1.27
0.45
393.0
0.40
0.018
22.58
393.0
0.005
5.97
28.55
30
10-yr
3.85
2.85
13
19.27
4.45
14.82
0.45
520.0
0.40
0.010
29.55
884.0
0.005
11.14
40.69
30
10-yr
3.85
33.38
14
19.49
4.50
14.99
0.45
520.0
0.40
0.010
29.55
920.0
0.005
11.48
41.03
30
10-yr
3.85
33.77
15
5.32
1.23
4.09
0.45
472.0
0.40
0.010
28.24
677.0
0.008
7.57
35.81
30
10-yr
3.85
9.21
16
25.91
5.98
19.93
0.45
520.0
0.40
0.010
29.55
1305.0
0.005
15.03
44.58
30
10-yr
3.85
44.89
17
1.77
0.41
1.36
0.45
571.0
0.40
0.009
31.64
n/a
31.64
30
10-yr
3.85
3.06
18
0.53
0.24
0.29
0.60
n/a
460.0
0.005
6.73
6.73
5
10-yr
7.88
2.50
19
1.69
0.39
1.30
0.45
222.0
0.40
0.009
20.36
345.0
0.005
5.40
25.75
30
10-yr
3.85
2.92
20
3.35
0.77
2.57
0.45
372.0
0.40
0.035
18.83
458.0
0.015
4.40
23.22
30
10-yr
3.85
5.80
21
3.96
0.91
3.04
0.45
372.0
0.40
0.035
18.83
646.0
0.010
6.70
25.53
30
10-yr
3.85
6.85
22
4.68
1.08
3.60
0.45
372.0
0.40
0.035
18.83
725.0
0.016
6.11
24.94
30
10-yr
3.85
8.10
23
1.57
0.36
1.21
0.45
374.0
0.40
0.009
25.97
340.0
0.005
5.34
31.31
30
10-vr
3.85
2.72
pnMed: 10/7/2021 3:02 PM Page 1 of 1