SW6240804_Design Calculations_20241015 (4)

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
2041-Drake Landing Subdivision
Rainfall Intensity
Storm Event
5-min 10-min 15-min 30-min Runoff Coeff.
10-yr 7.88 6.31 5.32 3.85 Impervious 0.95
25-yr 8.86 7.05 5.96 4.41 Grassed 0.20
50-yr 9.50, 7.57 6.39 4.82
100-yr 10.10 8.06 6.79 5.20
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 (m/hr)
L(ft) n s Toy L(ft) S TLIh
1 0.26 0.02 0.24 0.25 n/a 360.0 0.017 3.52 3.52 5 10-yr 7.88 0.50
2 1.00 0.53 0.47 0.60 n/a 560.0 0.012 5.60 5.60 5 10-yr 7.88 4.73
3 0.64 0.30 0.34 0.55 n/a 500.0 0.013 4.96 4.96 5 10-yr 7.88 2.77
4 0.52 0.24 0.28 0.55 n/a 445.0 0.013 4.52 4.52 5 10-yr 7.88 2.25
5 0.69 0.41 0.28 0.65 n/a 550.0 0.015 5.06 5.06 5 10-yr 7.88 3.53
6 0.00 0.00 n/a n/a 0.00 5 10-yr 7.88 0.00
7 0.84 0.17 0.67 0.35 n/a 510.0 0.011 5.31 5.31 5 10-yr 7.88 2.32
8 2.31 0.62 1.69 0.40 n/a 710.0 0.010 7.35 7.35 5 10-yr 7.88 7.28
9 4.11 0.55 3.56 0.30 n/a 1030.0 0.010 9.49 9.49 10 10-yr 6.31 7.78
10 5.21 0.69 4.52 0.30 n/a 1330.0 0.017 9.51 9.51 10 10-yr 6.31 9.86
printed: 8/27/2024 4:27 PM Page 1 of 1