Cleaning up our waterways - Tunnel boring set to begin for Coxwell Bypass Tunnel to improve quality of Toronto's waterways

TORONTODec. 14, 2019

Today Mayor John Tory and Councillor Jennifer McKelvie (Ward 25 Scarborough-Rouge Park), Vice-Chair of the Infrastructure and Environment Committee and the Mayor's Resilience and Environmental Champion, officially marked the beginning of tunnel boring for the Coxwell Bypass Tunnel. This project is the first stage of the Don River and Central Waterfront Wet Weather Flow System – one of five connected projects to improve water quality in the Lower Don River, Taylor-Massey Creek and along Toronto's Inner Harbour.

The City is investing more than $3 billion to keep combined sewer overflows out of our waterways, improving water quality in the Don River and along the central waterfront of Lake Ontario.

The tunnel boring machine (TBM), named Donnie, will dig the 6.3-meter diameter and 10.5-kilometer long Coxwell Bypass Tunnel, approximately 50 metres deep, parallel to the Don River.

The Coxwell Bypass Tunnel is an important part of the overall Don River & Central Waterfront (DR&CW) project. This tunnel will capture, store and transport combined sewer overflows, a mix of rainwater and sewage, for treatment at the Ashbridges Bay Treatment Plant.

Donnie the TBM is 115 metres in length and weighs nearly 1,000 tonnes. The machine was lowered into the 50-metre-deep and 20-metre-diameter shaft at the Ashbridges Bay Treatment Plant in sections and then assembled. Once testing is complete in the new year, the TBM will work its way west along Lake Shore Boulevard East to Don Roadway, north up the Don River valley to the North Toronto Treatment Plant and then east to the Coxwell Ravine Park shaft site where the tunnel ends.

The machine can bore at least 20 metres of tunnel per day. The Coxwell Bypass Tunnel is expected to be completed in 2024.

More information is available at A backgrounder about the Coxwell Bypass Tunnel and the Don River and Central Waterfront project is available at

"I am pleased to mark the arrival of the tunnel boring machine as the City prepares to dig the Coxwell Bypass Tunnel. Through this tunnel we can capture and store rain and wastewater and transport it for treatment and disinfection so clean water is released into the lake. This project is of great importance to our city and the future of our waterways. I am determined to secure the help of the federal and provincial governments to speed up this work so we can see the benefits of this project a decade earlier.
Toronto Mayor John Tory 

"The arrival of this massive tunnel boring machine is a real milestone for the Coxwell Bypass Tunnel work, the first of this multi-stage project. Years of planning, engineering and design will soon be realized as Donnie gets digging to create what will be a significant piece of infrastructure. This project will be of critical importance to our growing city and will improve the quality of Toronto's waterways which will benefit generations to come."
- Councillor James Pasternak (Ward 6, York Centre), Chair of the Infrastructure and Environment Committee

"The grand scale of the tunnel boring machine makes you realize the incredible scope and complexity of this project. I'm delighted to be here today to mark this momentous next step in a project that will bring considerable benefits in cleaning up Toronto's waterways and aquatic habitat and enhancing recreational opportunities for residents and visitors."
- Councillor Jennifer McKelvie (Ward 25, Scarborough-Rouge Park), Vice-Chair of the Infrastructure and Environment Committee

"As the local ward councillor, the Coxwell Bypass Tunnel project is part of the forward-thinking solution to the complex problem of improving the quality of Toronto's waterways. While this work is part of a longer-term connected system, the benefits will be well worth the wait."
- Councillor Paula Fletcher (Ward 14, Toronto-Danforth)

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