Page 422 - Planning and Design of Airports

Supply Curve Nos.
For paved 2.0
areas
For bare areas Drainage Section Assuming
For turfed 1.5
areas
Permissible
Drainage Area (DA), acres Ponding Length L, ft

= 0.40 and

Depth at Inlet, ft Pond Area, 1000 ft 2 Volume 1000 ft 3 Volume, ft 3 /acre DA Average Roughness Factor n Average Slope S, % Actual or Effective Length, ft L for n L Adopted for Selecting Diagrams

Unpaved
Paved, Equivalent = 1%
Inlet n = Turf n =
No. 0.02 Bare 0.40 Total S
1 2 3 4 5 6 7 8 9 10 11 12 13 14
4 5.97 26.81 32.78 0.33 2.0 575 330 330
3 5.69 25.54 31.23 0.33 2.8 575 280 280

2 5.69 25.54 31.23 0.33 2.8 575 280 280

Source: Corps of Engineers [8].
TABLE 9-6 Airfield Drainage—Drain Inlet Capacities

Supply Curve Nos.
For paved areas 2.0
For bare areas Drainage Section
For turfed areas 1.5

Critical Runoff Time to Produce Maximum Flow
Point of Design in Underground Drain Rate of
Distance, ft Drain time, min
From Assumed From Accu- Approxi-
Inlet From Pre- Velocity Pre- mula- mate t
c
or Main ceding Critical t , in Pipe, ceding tion (col. 5 + Adopted
c
Junction Outlet Inlet Inlet min ft/s Inlet Total col. 8) t , min , 4 3
c
1 2 3 4 5 6 7 8 9 10 11 12
4 4805 — 4 24 3.0 24 25 59.0
3 3155 1650 4 24 3.0 9.2 9.2 33 30 59.0 62.5
2 1505 1650 4 24 3.0 9.2 18.4 42 40 55.8 56.2
Source: Corps of Engineers [8].

TABLE 9-7 Airfield Drainage—Size and Profile of Underground Storm Drains