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St. Thomas Water Pollution Control Plant


St. Thomas, Ontario


Wastewater Treatment / Water Resource Recovery

Originally built in 1925, the St. Thomas Water Pollution Control Plant has been upgraded and expanded several times.

The plant currently has an average rated capacity of 27,300 cubic metres per day.

In 2012, the City of St. Thomas retained Associated Engineering to complete a structural condition assessment of the three digesters and prepare preliminary design documents and cost estimates for the rehabilitation of the digesters. We discovered the tank of Digester No. 2 required significant structural repairs to the concrete roof in order to pass the pressure testing requirements. We advised the City that similar structural issues would likely be uncovered in the remaining digesters. Due to the high structural repair costs required for the roof of Digester No. 2, we recommended to forego the work on Digesters No. 1 and No. 3.

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The City of St. Thomas

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Project Highlights

Associated Engineering recently completed a Digester Planning and Implementation Study. The goal of this study was to determine upgrade options, including life cycle costs, that would address both short-term and long-term needs of the anaerobic digestion system. Geotechnical and preliminary hydrogeological investigations have revealed some challenging areas with poor soils and requirement for dewatering. The impact of these conditions were included in the cost estimates to ensure the City allocates appropriate funds and contingencies.

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A career step in the right direction

We are recognized as one of Canada’s Best Managed Companies for 14 consecutive years but our achievements and reputation are only possible because of our amazing staff. We believe that a supported staff allows them to excel at what they do best, and provide the best possible service to our clients and communities.