Methodological approach for the optimization of a dynamically controlled bypass chamber

Overflows from combined sewer systems are one of the main sources of urban pollutants discharged into the environment. 

In such networks, the use of the storage capacity available during frequent rain events may reduce overflows at the networks’ outfalls. To achieve this, it is important to manage flow derivations optimally at the bypass chambers during high flows likely to induce flooding, as well as in dry weather or between two rain events so that very low flows can be routed to receive treatment. 

This paper describes an original method to obtain accurate and reliable data to optimize the operation of a bypass chamber to be built on the City of Montreal’s major collector. It consists in combining a one-dimensional hydrological-hydraulic model, a theoretical model, and a three-dimensional Computational Fluids Dynamics (CFD) model. 

The analysis and simulations were carried out under steady-state and transient conditions using a one-dimensional model PCSWMM, a theoretical under-valve flow model proposed by Kréménetski and a three-dimensional model of the bypass structure using the ANSYS CFX software. The structure’s geometry was provided by the City in AutoCAD plans which were transferred to the CFD model using SolidWorks Premium 2014 and ANSYS Mesh. 

The desired objectives of the project were met successfully and recommendations were made regarding the configuration and hydraulic capacity of the drop structure at the reservoir’s inlet and the positioning of the measuring devices to be installed in the bypass chamber. 

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