SW6220805_Design Calculations (Time of Concentration)_20221019

[CALCULATIONS
sheet only set up to handle Tc from 5 min to 30 min
A. Flow velocity < 2.0 fps when discharging to wetlands B. Flow velocity < 4.5 fps all other cases"
Storm Event
Rainfall Intensity
5-min
10-min
15-min
30-min
10-yr
7.88
6.31
5.32
3.85
25-yr
8.80
7.01
5.92
4.38
50-yr
9.48
7.55
6.37
4.80
100-yr
10.101
8.051
6.781
5.19
Ditch No. Drainage Impervious Grassed C
Area (ac) I Area (ac) I Area (ac)
1 0.27
0.06
0.21
0.45
2 1.76
0.41
1.35
0.45
3 2.47
0.19
2.28
0.35
4 0.21
0.05
0.16
0.45
5 0.22
0.05
0.17
0.45
6 1.58
0.24
1.34
0.40
7 1.24
0.19
1.05
0.40
8 0.21
0.05
0.16
0.45
Kerby
L (ft) n s
T-
n/a
n/a
n/a
n/a
n/a
n/a
n/a
n/a
Tc
L (ft)
335.0
650.0
950.0
290.0
295.0
700.0
565.0
240.0
Kirpich
S
0.010
0.010
0.008
0.005
0.005
0.005
0.005
0.010
C. Channel slope < 5.0% for curb outlet swales
Rainfall
Stonn
Intensity
Q (cfs)
Total Tc
Tc Used
Event (yr)(in/hr)
Tin
4.04
4.04
5
10-yr
7.88
0.96
6.73
6.73
5
10-yr
7.88
6.24
9.82
9.82
10
10-yr
6.31
5.45
4.72
4.72
5
10-yr
7.88
0.74
4.78
4.78
5
10-yr
7.88
0.78
9.31
9.31
10
10-yr
6.31
3.99
7.89
7.89
10
10-yr
6.31
3.13
3.13
3.13
5
10-yr
7.88
0.74
printed: 10/19/2022 425 PM Page 1 of 1