n
|
=
|
0.013 concrete pipe
| |
n
|
=
|
0.02 polyethylene pipe (corrugated interior)
| |
n
|
=
|
0.012 polyethylene pipe (smooth interior)
|
n
|
=
|
0.013 for best concrete-lined ditch
| |
n
|
=
|
0.025 for best unlined ditch
| |
n
|
=
|
0.03 to 0.15 for fair to poor natural streams and watercourses
|
Excavation Material
|
Velocity
(feet per second)
| |
---|---|---|
Fine sand and firm loam
|
2.50 to 3.5
| |
Grass-lined ditch
|
4 to 5
| |
Stiff clay and hardpan
|
3.75 to 6.0
| |
Concrete-lined ditch
|
10
|