Mid Halton Wastewater Treatment Plant

Regional Municipality of Halton | Canada | 2010–Ongoing

Award of Excellence at the 2020 Canadian Consulting Engineering Awards

438 mld
peak capacity UV disinfection

37 m diameter
anaerobic digester; chemical storage and feed facility

2 new
aeration tanks


  • Conservation efforts have recently been made to clean Lake Ontario, the 14th largest lake in the world, as pollution has largely destroyed its commercial fishing industry.
  • Meet demand and continue protecting Lake Ontario's water by increasing the Mid Halton Wastewater Treatment Plant's capacity from 75 million liters per day (mld) to 125 mld.
  • Upgrade the plant’s headworks and install a new outfall tunnel, giving utmost consideration to crossing the environmentally sensitive 14 Mile Creek when planning the most direct route.
  • Protect the creek habitat for two owl species and Redside Dace fish, a government-designated endangered species requiring pools and slow-flowing streams with overhanging grasses and shrubs.


  • Provide primary design consultation services for the Mid Halton Wastewater Treatment Plant phase IV and V, including expansion and extensive upgrades to the headworks and outfall.
  • Design the headworks in 3D to give all stakeholders a clear view of the plan as it progressed.
  • Design a new outfall tunnel to run 1.3 miles onshore and another 2.7 miles offshore to an 85-to-98-foot underwater diffuser field in the final 300 feet.
  • Run the tunnel through bedrock, beneath a major highway and across the environmentally-sensitive area, drawing on our invaluable expertise in tunneling technology and computer modeling.


  • Final plan selection and outfall alignment required significant coordination with the Ontario Ministry of Natural Resources and the local conservation authority.
  • Ably demonstrated that our design and proposed construction methods would allow an alignment that crossed 14 Mile Creek while protecting the specialized habitat of the Redside Dace.
  • Ensured the area's needs are met for the foreseeable future, and Lake Ontario's water and the environment around the town of Oakville are protected.
  • Recipient of Award of Excellence in the Water Resources category at the 2020 Canadian Consulting Engineering (CCE) Awards.

Project numbers

C$140 million in construction costs for wastewater treatment plant
C$90 million in construction cost for the outfall tunnel

What's your challenge?