Water Service - Wastewater Treatment

Welland WWTP Class Environmental Assessment


The Regional Municipality of Niagara


Welland, ON



Biggest Hurdle:

Integration of dry and wet weather treatment needs.

 In the Welland WWTP Schedule C Class Environmental Assessment (Class EA), XCG Consultants Ltd. reviewed options to upgrade and expand the existing facility from an average day flow capacity of 54,550 m³/d to treat flows up to 65,000 m³/d. The existing WWTP services the City of Welland and the communities of Pelham, Port Robinson, and South Thorold. Treatment is provided by the conventional activated sludge process, with tertiary filtration to reduce the concentration of phosphorus entering the Welland River, a sensitive receiver tributary to the Niagara River. As part of the study, an assimilative capacity was completed to identify effluent criteria for the upgraded facility. Parts of the City of Welland are served by combined sewers. Included in the Welland WWTP Class EA was an initial analysis of options to manage wet weather flows and an update of the conclusion of a 2003 Class EA for Combined Sewer Overflow Management. The existing facility is capable of providing physical/chemical treatment during wet weather. The plant can be operated in storm mode where the physical/chemical treatment and disinfection is provided for an additional wet weather capacity of 54,500 m3/d. The challenge in this project was to integrate dry and wet weather treatment needs for the service area.


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Options that were considered to expand the Welland WWTP included expansion of the existing conventional activated sludge process and retrofitting the existing works to operate as a Moving Bed Bioreactor (MBBR) or Integrated Fixed Film Activated Sludge (IFAS) process. The preferred option was expansion of the existing conventional activated sludge process. Public consultations, including two Public Information Centres (PICs), were a key part of the Class EA process.