American Society of Civil Engineers

Minimum Self-Cleansing Velocities for Inverted Sewer Siphons

by Richard W. P. May, (Water Management Department, HR Wallingford, Oxfordshire, England, OX10 8BA E-mail:
Section: Combined and Sanitary Sewer, pp. 173-183, (doi:

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Document type: Conference Proceeding Paper
Part of: Urban Drainage Modeling
Abstract: Laboratory experiments were carried out to determine minimum self-cleansing velocities for preventing deposition of sediment in upward sloping and vertical pipes of inverted siphons. Tests were made using sediment sizes of 0.78mm and 4.3mm in a pipe of 150mm diameter for eight angles of inclination between 0° and 90°. The criterion for self-cleansing was defined as the minimum velocity needed to prevent the formation of separated dunes in the pipes. For a given sediment concentration the self-cleansing velocity was found to be a maximum at pipe slopes between about 30° and 37.5°. Analysis of the data enabled the results to be described by a single formula valid for any slope of pipe between horizontal and vertical.

ASCE Subject Headings:
Urban areas