By Gianfranco Maragno, P. Eng. And Martin Couture, P. Eng., Veolia Water Technologies Canada
Overflow events occur during wet weather when the collection system reaches its maximum storage capacity. Traditionally, a compromise must be struck between the sewer’s in-line retention and the risk caused by a higher hydraulic grade line (HGL). To address this dilemma, a careful optimization of the system’s overflow weirs is required. This paper introduces the use of linear overflow devices that can help municipal engineers achieve both increased retention capacity, while protecting the system against flooding. Examples of application will be presented where the required water head will be lowered by 50% for the same overflow rate.