Courtright Wastewater Treatment Plant Expansion

St. Clair Township is expanding its Courtright Wastewater Treatment Plant to create capacity for 624 new homes and future industrial growth. NAC and engineering partner WSP Canada Inc. are leading the project from design through construction under a Progressive Design-Build model.

The Courtright Wastewater Treatment Plant treats residential wastewater and pre-treated industrial flows from Corunna, Mooretown and Courtright. Rated capacity will increase from 6,000 m³/day to 9,000 m³/day, with key new processes sized to allow for simpler future expansion. The expansion will also add a new secondary clarifier, a two-stage aerobic digester and upgraded screening, grit removal and UV disinfection.

The Township brought the design-build team on to the project during the early design stage. As the design progressed, it became clear the original expansion scope exceeded the available budget. To control capital costs, the team evaluated three treatment technologies capable of increasing capacity within a smaller footprint, comparing the options on expandability, operating flexibility, maintenance and the changes each would require at the existing plant. NAC’s in-house construction and cost expertise informed each decision, keeping the design moving quickly.

Ultimately, the team selected a membrane aerated biofilm reactor (MABR) process. Installed in the plant’s two existing aeration tanks, 28 MABR cassettes will provide the added capacity without requiring new tanks, leaving room to nearly double the cassette count as flows grow. Early procurement also kept the project moving. NAC committed to the MABR and other process equipment early to help finalize the design and shop drawing reviews and sourced a shelf-ready generator instead of a custom unit, saving the project six months.

Construction began with a groundbreaking ceremony on July 14, 2026. With permits in place and bulk excavation complete, crews are now placing the tank base slabs. NAC is staging the work, including a headworks bypass, so the plant stays fully operational throughout construction, and has planned truck routes with Township staff to limit impacts on nearby residents. Project completion is targeted for March 2028.