|
Surface
|
Manning n |
|
Smooth Asphalt |
0.011 |
|
Smooth Concrete |
0.012 |
|
Ordinary Concrete Lining |
0.013 |
|
Good Wood |
0.014 |
|
Brick with Cement Mortar |
0.014 |
|
Vitrified Clay |
0.015 |
|
Cast Iron |
0.015 |
|
Corrugated Metal Pipes |
0.024 |
|
Cement Rubble Surface |
0.024 |
|
Fallow Soils (No Residue) |
0.05 |
|
Cultivated Soils |
|
|
Residue Cover < 20% |
0.06 |
|
Residue Cover > 20% |
0.17 |
|
Range (Natural) |
0.13 |
|
Grass |
|
|
Short, Prairie |
0.15 |
|
Dense |
0.24 |
|
Bermuda Grass |
0.41 |
|
Woods |
|
|
Light Underbrush |
0.40 |
|
Dense Underbrush |
0.80 |
Source: McCuen, R. et al. (1996), Hydrology, FHWA-SA-96-067, Federal Highway Administration, Washington, DC.
|
Conduit Material
|
Manning n |
|
Asbestos-Cement Pipe |
0.011 - 0.015 |
|
Brick |
0.013 - 0.017 |
|
Cast Iron Pipe |
|
|
Cement-Lines & Seal Coated |
0.011 - 0.015 |
|
Concrete (Monolithic) |
|
|
Smooth Forms |
0.012 - 0.014 |
|
Rough Forms |
0.015 - 0.017 |
|
Concrete Pipe |
0.011 - 0.015 |
|
Corrugated-Metal Pipe (12.7mm x 67.7mm corrugations) (1/2in x 2-2.3in corrugations) |
|
|
Plain |
0.022 - 0.026 |
|
Paved Invert |
0.018 - 0.022 |
|
Spun Asphalt Lined |
0.011 - 0.015 |
|
Plastic Pipe (Smooth) |
0.011 - 0.015 |
|
Vitrified Clay |
|
|
Pipes |
0.011 - 0.015 |
|
Liner Plates |
0.013 - 0.017 |
Source: ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of Practice No. 60, New York, NY.
|
Conduit Material
|
Manning n |
|
Linked Channels |
|
|
Asphalt |
0.013 - 0.017 |
|
Brick |
0.012 - 0.018 |
|
Concrete |
0.011 - 0.020 |
|
Rubble or Riprap |
0.020 - 0.035 |
|
Vegetal |
0.030 - 0.40 |
|
Excavated or Dredged |
|
|
Earth, Straight and Uniform |
0.020 - 0.030 |
|
Earth, Winding and Fairly Uniform |
0.025 - 0.040 |
|
Rock |
0.030 - 0.045 |
|
Unmaintained |
0.050 - 0.140 |
|
Natural Channels (minor streams, top width at flood stage < 30.5m (100ft)) |
|
|
Fairly regular section |
0.030 - 0.070 |
|
Irregular section with pools |
0.040 - 0.100 |
Source: ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of Practice No. 60, New York, NY.