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 = 300 - 400 mm v > 0,9 m/s for D = 450 - 500 mm v > 0,95 m/s for D = 600 - 800 mm v > 1,00 m/s for D = 900 - 1200 mm v > 1,05 m/s for D = 1200 - 1500 mm v > 1,10 m/s for D > 1500 mm

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)

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

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

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

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