SW6210601_Design Calculations (Tc)_20210603

1656 — Graceland Subdivision
Ditch Tc Calculations
Ditch #1
DI-39 inlet
Tc = 27.0 + 4.2 min = 31.2 min, use 30 min
Kerby: L = 412 ft; n = 0.5; s = 0.009
Kirpich: L = 252 ft; s = 0.005
Ditch #2
DI-37 inlet
Tc = 19.9 +5.6 min = 25.4 min, use 30 min
Kerby: L = 303 ft; n = 0.4; s = 0.018
Kirpich: L = 362 ft; s = 0.005
Ditch #3
DI-65
Tc = 28.1 + 2.5 min, use 30 min
Kerby: L = 472 ft; n = 0.4; s = 0.01
Kirpich: L = 125 ft; s = 0.01