SW6231112_Design Calculations (Swale Flow)_20240117

4D Site Solutions, Inc.
DITCH CALCULATIONS
1997-Brayden Preserve Subdivision
Rainfall Intensity
Storm Event
5-min 10-min 15-min 30-min RunoffCoeff.
10-yr 7.69 6.16 5.20 3.76 Impervious 0.95
25-yr 8.59 6.85 5.79 4.29 Grassed 0.30
50-yr 9.19 7.33 6.18 4.66
100-yr 9.76 7.76 6.54 5.01
Tc
Drainage Impervious Grassed Storm Rainfall
Ditch No. C Kirpich Intensity Q(cfs)
Area(ac) Area(ac) Area(ac) Event(yr)
Total Tc Tc Used (m/hr)
L(ft) S Toh
1 0.14 0.03 0.11 0.45 180.0 0.064 1.23 1.23 5 10-yr 7.69 0.48
2 0.38 0.09 0.29 0.45 450.0 0.023 3.67 3.67 5 10-yr 7.69 1.32
3 0.74 0.17 0.57 0.45 410.0 0.062 2.34 2.34 5 10-yr 7.69 2.55
4 0.58 0.13 0.44 0.45 590.0 0.035 3.87 3.87 5 10-yr 7.69 2.00
5 0.82 0.19 0.63 0.45 520.0 0.058 2.89 2.89 5 10-yr 7.69 2.82
6 3.32 0.77 2.55 0.45 890.0 0.035 5.30 5.30 5 10-yr 7.69 11.47
7 1.82 0.42 1.40 0.45 580.0 0.039 3.66 3.66 5 10-yr 7.69 6.31
8 5.27 1.22 4.06 0.45 875.0 0.036 5.17 5.17 5 10-yr 7.69 18.25
9 0.37 0.09 0.29 0.45 450.0 0.031 3.28 3.28 5 10-yr 7.69 1.29
10 0.68 0.16 0.53 0.45 390.0 0.041 2.64 2.64 5 10-yr 7.69 2.37
11 1.14 0.26 0.88 0.45 450.0 0.031 3.28 3.28 5 10-yr 7.69 3.96
12 1.62 0.37 1.25 0.45 660.0 0.051 3.63 3.63 5 10-yr 7.69 5.60
13 4.02 0.93 3.09 0.45 970.0 0.031 5.93 5.93 5 10-yr 7.69 13.91
14 0.06 0.01 0.05 0.45 120.0 0.050 0.99 0.99 5 10-yr 7.69 0.21
15 1.78 0.41 1.37 0.45 565.0 0.037 3.65 3.65 5 10-yr 7.69 6.16
16 1.40 0.32 1.08 0.45 350.0 0.045 2.34 2.34 5 10-yr 7.69 4.86
17 7.03 1.62 5.41 0.45 1130.0 0.027 7.03 7.03 5 10-yr 7.69 24.32
18 2.05 0.47 1.57 0.45 680.0 0.047 3.84 3.84 5 10-yr 7.69 7.08
19 0.38 0.09 0.30 0.45 650.0 0.048 3.68 3.68 5 10-yr 7.69 1.33
20 1.13 0.26 0.87 0.45 600.0 0.055 3.28 3.28 5 10-yr 7.69 3.92
21 2.18 0.50 1.68 0.45 830.0 0.045 4.55 4.55 5 10-yr 7.69 7.55
22 0.95 0.15 0.81 0.40 625.0 0.050 3.50 3.50 5 10-yr 7.69 2.93
23 10.77 1.66 9.11 0.40 1225.0 0.036 6.70 6.70 5 10-yr 7.69 33.14
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4D Site Solutions, Inc.
Ditch No. infll
Drainage Impervious Grassed C Kirpich Tc Storm Intensity Q(cfs)
Area(ac) Area(ac) Area(ac) L(ft) S To Total Tc Tc Used Event(yr) (ice)
24 0.88 0.14 0.74 0.40 400.0 0.045 2.60 2.60 5 10-yr 7.69 2.70
25 0.41 0.06 0.34 0.40 330.0 0.038 2.39 2.39 5 10-yr 7.69 1.25
26 3.13 0.48 2.65 0.40 705.0 0.047 3.95 3.95 5 10-yr 7.69 9.64
27 0.38 0.06 0.32 0.40 460.0 0.048 2.82 2.82 5 10-yr 7.69 1.16
28 4.01 0.62 3.39 0.40 850.0 0.042 4.77 4.77 5 10-yr 7.69 12.33
29 0.55 0.08 0.47 0.40 830.0 0.048 4.43 4.43 5 10-yr 7.69 1.70
30 3.42 0.53 2.89 0.40 820.0 0.057 4.13 4.13 5 10-yr 7.69 10.51
31 0.31 0.05 0.26 0.40 450.0 0.049 2.75 2.75 5 10-yr 7.69 0.96
32 1.51 0.23 1.28 0.40 520.0 0.056 2.92 2.92 5 10-yr 7.69 4.64
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