A.7 Manning's N -Closed Conduits
| Conduit Material | Manning n |
| Asbestos-cement pipe | 0.011 - 0.015 |
| Brick | 0.013 - 0.017 |
| Cast iron pipe Cement-lined & seal coated | 0.011 - 0.015 |
| Concrete (monolithic) Smooth forms Rough forms | 0.012 - 0.014 0.015 - 0.017 |
| Concrete pipe | 0.011 - 0.015 |
| Corrugated-metal pipe (1/2-in. x 2-2/3-in. corrugations) Plain Paved invert Spun asphalt lined | 0.022 - 0.026 0.018 - 0.022 0.011 - 0.015 |
| Plastic pipe (smooth) | 0.011 - 0.015 |
| Vitrified clay Pipes Liner plates | 0.011 - 0.015 0.013 - 0.017 |
Source: ASCE (1982). Gravity Sanitary Sewer Design and Construction, ASCE Manual of Practice No.60, New York, NY.