MTE's Involvement
MTE began the project by leading a Schedule B Class Environmental Assessment (EA) to evaluate sanitary servicing options and recommend the best course of action. Our team conducted a comprehensive series of environmental, hydrogeological, geotechnical, cultural heritage, and archaeological studies to support the EA. Public engagement was also key—our team worked with local residents, First Nations communities, and a variety of stakeholders through meetings and a Public Information Centre to gather valuable input and minimize community and environmental disruption.
Following the EA, MTE determined that the optimal solution was to decommission the old pumping station and build a new facility on the opposite side of Old Mill Road. We completed the preliminary and detailed design for the new 150 L/s sanitary pumping station, which includes an emergency storage tank with tipping buckets, a divided wet well with rock trap and grinder, a dry well with three pumps, and a control building housing a pump hoist room (with odour control unit), generator room, electrical room, and washroom. A larger forcemain, new inlet sanitary sewer, and re-routed watermain were also designed to accommodate the new facility.
MTE also led contract administration during construction of the new station and decommissioning of the old one. One of the project’s biggest challenges was its difficult geotechnical and hydrogeological conditions. The site, located within a glacial outwash area, contained coarse gravel and stone deposits extending over 30 metres to bedrock, resulting in high groundwater flow through porous soils.
To address this, MTE designed and implemented a robust soil retention and shoring system, including sheet piling and secant walls, to allow safe excavation to depths exceeding 12.5 metres below ground. Limited space for material storage required further innovation—soil retention systems were used to minimize material sent to landfill. Additionally, the high water table necessitated significant dewatering efforts, water quality management, and flotation analysis to prevent uplift of the structure during flood events.
MTE’s experience and adaptive approach throughout the design and construction phases ensured that the new station met both technical and environmental demands. MTE’s work on the Old Mill Sanitary Pumping Station was recognized with a 2023 Award of Merit and Diamond Award from the Association of Canadian Engineering Companies – Grand River Chapter.