Tunnel Boring Set to Begin for Coxwell Bypass Tunnel

By TBM Staff December 16, 2019

On Dec. 14, 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 Harbor.

The City is investing more than $3 billion to keep combined sewer overflows out of 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-m diameter and 10.5-km long Coxwell Bypass Tunnel, approximately 50 m 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 m in length and weighs nearly 1,000 tonnes. The machine was lowered into the 50-m deep and 20-m 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 is expected to bore at least 20 m of tunnel per day. The Coxwell Bypass Tunnel is expected to be completed in 2024. The project is being built by a joint venture of Jay Dee, Michels and C&M McNally. Designers are Black & Veatch and R.V. Anderson.

A backgrounder about the Coxwell Bypass Tunnel and the Don River and Central Waterfront project is available here.