The City of Sault Ste. Marie is about to get a major upgrade in their wastewater treatment.

Approximately 25,000 people fall into the area treated by the West End Wastewater Treatment located at 55 Allen’s Side Road. Originally commissioned in 1985, it is one of two wastewater treatment plants servicing the City’s current population of 73,000. Currently rated for a treatment capacity of 20 million litres of wastewater per day, no major upgrades have been completed to the plant since the original construction—until now.

The $38 million project consists of a major overhaul to both the preliminary treatment and solids treatment processes, says Catherine Taddo, Manager, Development and Environmental Engineering for Public Works and Engineering Services.

A new screening building was constructed containing two new screening channels equipped with fine step screens each rated for 50 MLD to handle the peak wet weather flows. The new screens provide a significant improvement in removal of screenings and some FOG (fats, oils, and grease) to protect downstream processes and equipment. Screening washer-compactors were also installed to reduce the screenings moisture content, and thus weight, to reduce lifecycle costs of disposal. The existing grit vortex tanks were also retrofitted from an air-lift configuration to a pumped system.

A new septage receiving building was constructed and is equipped with automated valving, flow metering, sampling, a grinder and rock trap. These upgrades facilitate an automated septage receiving, conditioning, and monitoring process which was previously unavailable.

The solids treatment process was overhauled with existing thickening and dewatering processes replaced with rotary drum thickening and centrifuging processes. Most of the new equipment was installed within the existing sludge handling building to maximize the usage of existing infrastructure. Rotary drum thickeners, centrifuges, sludge pumps, and new conveyance equipment was implemented within the existing building, while new tankage was provided for sludge holding between processes.

The core electrical infrastructure was also overhauled including new switchgear, MCCs, and distribution wiring. Two standby generators were installed which can provide sufficient power to run the entire plant during a power outage with full redundancy. New energy-efficient lighting was also installed throughout the facility, creating another environmentally-friendly element to the project.

The project also consisted of the following miscellaneous upgrades to the facility:
• Effluent water booster pumping upgrades to provide required pressure for the new dewatering equipment.
• Upgrades to building mechanical equipment, including replacement of air handling units, ducting, odour control fans and stacks.
• Upgrades and repairs to various structural, architectural and electrical components of existing facilities.
• Installation of two new walk-in backup generators.
• Various road, fencing, and site civil works.

The future Phase II upgrades will consist of an overhaul to the disinfection systems and the liquid stream treatment capacity to service the projected population into the future.

With work still ongoing, “the project is scheduled to be completed in 2023,” says Taddo. Lifespan varies by component, whether it be civil works, structural, architectural, process and mechanical, piping and gates, electrical, and/or instrumentation and controls, and other variables. Structural components for critical municipal infrastructure are designed for a ‘post-disaster’ importance category as per the Ontario building code and typically have a service life of about 50 to 75 years. Mechanical and electrical equipment components have a much shorter service life of approximately 20 to 30 years.

Beyond the direct impact of upgrades to the City’s infrastructure, the construction has also brought a boost to the local economy including job creation for skilled trades, and the associated engineering work.

The project design and construction oversight was provided by AECOM Canada Ltd and Maple Reinders completed the construction.

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