Sewer design calculations

Calculate the design diameter and slope for a section of sewer pipe.

The Manning Equation is used for Calculation of Pipe Diameter and Slope.

Input data are design flow, elevations of ground initial and final.

The app can be used in the SI or US units.

Example: The design flow rate for a section of storm sewer between two manholes is: Qdes = 10 l/s. Find a combination of a standard pipe diameter and pipe slope to use for this section of sewer to meet the criteria of minimun tractive force.

The required minimum tractive force for sanitary sewer in the app is considered as 2 N/m2.

See solution of example in the screenshot.

- Initial ground elevation = 10 m (ground elevation of initial and final manholes is used to calculate the ground slope and check that slope of the pipe is not less than ground).

- Final ground elevation = 9 m

- Length of pipe = 60 m

- Desired flow = 40 liters per seconds

And as a result of the design, after pressing the calculate button, we get the following results:

Slope: 0.02 m / m, equivalent to 2%

Pipe diameter: 0.3 m

height of water in the pipe (depth / diameter): 40%