SW6240607_Design Calculations_20240830 (15)

4D Site Solutions, Inc.
DITCH CALCULATIONS
NOTE: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** C. Channel slope<5.0%for curb outlet swales
2029-Rolling Springs Section 9
Rainfall Intensity
Storm Event
5-min 10-min 15-min 30-min Runoff Coeff.
10-yr 7.79 6.23 5.25 3.80 Impervious 0.95
25-yr 8.70 6.93 5.86 4.34 Grassed 0.30
50-yr 9.29 7.41 6.25 4.71
100-yr 9.86 7.84 6.61 5.06
Tc
Drainage Impervious Grassed 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 Toy L(ft) S Tet,
1 0.36 0.14 0.22 0.55 n/a 290.0 0.050 1.95 1.95 5 10-yr 7.79 1.54
2 0.69 0.11 0.58 0.40 n/a 394.0 0.033 2.90 2.90 5 10-yr 7.79 2.15
3 0.43 0.13 0.30 0.50 n/a 400.0 0.020 3.55 3.55 5 10-yr 7.79 1.67
4 0.84 0.19 0.65 0.45 n/a 360.0 0.040 2.50 2.50 5 10-yr 7.79 2.94
5 1.47 0.34 1.13 0.45 n/a 480.0 0.038 3.20 3.20 5 10-yr 7.79 5.15
6 2.26 0.52 1.74 0.45 n/a 700.0 0.045 3.99 3.99 5 10-yr 7.79 7.92
7 2.65 0.61 2.04 0.45 n/a 870.0 0.049 4.55 4.55 5 10-yr 7.79 9.29
8 3.25 0.75 2.50 0.45 n/a 990.0 0.044 5.26 5.26 5 10-yr 7.79 11.39
9 4.24 0.98 3.26 0.45 n/a 820.0 0.043 4.59 4.59 5 10-yr 7.79 14.86
10 4.58 1.06 3.52 0.45 n/a 990.0 0.064 4.55 4.55 5 10-yr 7.79 16.06
11 5.08 1.17 3.91 0.45 n/a 1100.0 0.061 5.04 5.04 5 10-yr 7.79 17.81
12 3.76 0.87 2.89 0.45 n/a 1155.0 0.060 5.25 5.25 5 10-yr 7.79 13.18
13 0.23 0.07 0.16 0.50 n/a 180.0 0.045 1.40 1.40 5 10-yr 7.79 0.88
14 7.92 1.83 6.09 0.45 n/a 1530.0 0.054 6.79 6.79 5 10-yr 7.79 27.76
15 0.11 0.04 0.07 0.55 n/a 160.0 0.046 1.27 1.27 5 10-yr 7.79 0.47
16 0.31 0.09 0.21 0.50 n/a 385.0 0.051 2.39 2.39 5 10-yr 7.79 1.19
17 0.31 0.10 0.22 0.50 n/a 185.0 0.029 1.70 1.70 5 10-yr 7.79 1.21
18 0.13 0.05 0.08 0.55 n/a 170.0 0.040 1.41 1.41 5 10-yr 7.79 0.57
19 1.00 0.23 0.77 0.45 n/a 500.0 0.014 4.78 4.78 5 10-yr 7.79 3.51
20 0.30 0.11 0.18 0.55 n/a 370.0 0.051 2.33 2.33 5 10-yr 7.79 1.26
21 0.42 0.13 0.29 0.50 n/a 350.0 0.053 2.20 2.20 5 10-yr 7.79 1.64
22 0.37 0.14 0.23 0.55 n/a 470.0 0.050 2.82 2.82 5 10-yr 7.79 1.61
printed: 8/30/2024 3:49 PM Page 1 of 2

4D Site Solutions, Inc.
23 0.66 0.20 0.46 0.50 n/a 445.0 0.054 2.63 2.63 5 10-yr 7.79 2.57
Drainage Impervious Grassed Tc Storm Rainfall
Ditch No. C Kerby Kirpich Intensity Q(cfs)
Area(ac) Area(ac) Area(ac) L(ft) n s Toy L(ft) S Tch Total Tc Tc Used Event(yr) (in/hr)
24 1.28 0.39 0.89 0.50 n/a 590.0 0.048 3.41 3.41 5 10-yr 7.79 4.99
printed: 8/30/2024 3:49 PM Page 2 of 2