Thornbury Wastewater Plant Expansion Wraps Up: Ribbon Cutting Set for May 20
After nearly four years of construction, one of the largest infrastructure projects in The Blue Mountains’ recent history is crossing the finish line. The Town is inviting residents to a ribbon cutting and open house at the Thornbury Wastewater Treatment Plant on Wednesday, May 20, 2026 at 10:00 a.m., marking the substantial completion of the Phase 1A Expansion.
Why the expansion mattered
The original Thornbury plant was built in 1994 with a rated capacity of 3,580 cubic metres per day. With a growing community and aging equipment, the facility was approaching the limits of what it could reliably handle. Council approved the expansion as part of the 2020 budget, with a clear goal: replace end-of-life equipment and lift the plant’s capacity to keep pace with forecasted growth, without compromising the quality of water flowing back into Georgian Bay.
What got built
Once construction kicked off in 2022, crews delivered a significant overhaul of the site:
- A new extended aeration tank and new clarifier, raising treatment capacity to 5,330 m3/day
- An expanded ultraviolet disinfection system sized to the new flow
- Replacement of the plant’s air blowers, controls, valves and distribution piping
- A new mechanical screening system at the headworks
- Energy-efficiency upgrades throughout the facility
- A brand-new outfall pipe running 1,500 metres into Georgian Bay. The first 600 m is dredged into the lakebed and the remaining 900 m lays along the bottom, with marine work timed around the 2025 fisheries windows
By late August 2025, all new operational equipment had been installed and handed over to the Town’s wastewater operators for a 45-day test period. Final restoration, including paving, hydroseeding and clean-up, has been wrapping up through the spring.
A community milestone
The project has not been without its bumps. Council approved a budget increase to 29 million dollars in April 2023 to keep the construction tender on track, and the scope grew along the way to include the new outfall.
Still, the May 20 event is a chance for residents to see what their investment delivered, meet the staff who will run it for decades to come, and mark a real upgrade for the community’s environment and capacity to grow. Doors open at 10 a.m. All welcome.
