TEPPFA - FAQ Sewer in Civils

Due to their lower roughness coefficient the full bore capacity of plastic sewer pipes can be 30% more than a concrete sewer pipe of the same diameter.

Details

Based on recommendations published by the UK Hydraulic Research Establishment the roughness coefficient which should be used for slimed plastic sewers is 0.6 mm and for slimed concrete sewers a value of 3.0 mm is recommended.

For storm water applications a roughness coefficient of 0.06 is recommended for plastics and a value 0.15 for concrete pipes.

As an example, from the tables published by the UK Hydraulic Research Establishment (using the above recommendations for roughness coefficients) a 300 mm diameter slimed plastic sewer at a gradient of 1 in 200 has a full bore discharge rate of 90 l/s compared to 69 l/s for a slimed concrete sewer pipe of the same diameter.

Want to Know More?

See "Tables for the hydraulic design of pipes, sewers and channels" produced by the Hydraulic Research Establishment.

See also CEN TS 15223 (Plastic piping systems - Validated design parameters of buried thermoplastics piping systems).

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