1. Topic II. 8. Hydraulic Dimensioning of Sewers
Velocity Requirements
Maximal velocities
Combined sewer system and drainage pipes at separate sewer system
v < 7 m/s (non-metal pipes)
v < 10 m/s (metal pipes)
Sanitary sewer pipes at separate sewer system
v < 4 m/s (non-metal pipes)
v < 8 m/s (metal pipes)
Minimal velocities (depending on the pipe diameter)
v > 0,7 m/s for D < 250 mm
v > 0,8 m/s for D = mm
v > 0,9 m/s for D = mm
v > 0,95 m/s for D = mm
v > 1,00 m/s for D = mm
v > 1,05 m/s for D = mm
v > 1,10 m/s for D > 1500 mm

2. Hydraulic Dimensioning of Sewers
Sewer Slopes Requirements
Velocity - slope relationship (Manning) 
Minimal slopes (classical empirical rule)
Minimal non-settling velocity (Fedorov)
Minimal non-settling slope (by Fedorov)

3. Hydraulic Dimensioning of Sewers
Sewer Pipes Minimal Diameter Requirements
Combined sewer system and drainage pipes at separate sewer system
Dmin = 300 mm for the street pipelines
Dmin = 200 mm for pipelines at industrial areas
Dmin = 150 mm for pressure pipes
Dmin = 200 mm for service connections to the public sewers
and/or to the drainage network
Sanitary sewers at separate sewer system
Dmin = 300 mm for the street pipeline

4. Hydraulic Dimensioning of Sewers
Basic Relationships and Problems
Flow parameters: Q, v, D, I, i, h/D
Relationships available:
Number of parameters to be adopted - 2

5. Hydraulic Dimensioning of Sewers
Kinds of Problems
Simulation problem
Adopted/given - D, i
Searched for - Q, v, I, h/D
Tracing problem
Adopted/given - D, Q
Searched for - i, v, I, h/D
Design problem
Adopted/given - Q, v
Searched for - D, i, I, h/D

6. Hydraulic Dimensioning of Sewers
Sewer Pipes Design
Design wastewater quantity - Qd
a) Combined sewer system
Qd = Qds + Qr
b)Separate sewer system
Design velocities - vd