A unique application of Diaphragm Wall to facilitate the excavation of New River Channel on The Port Lands Flood Protection and Enabling Infrastructure Project in Toronto, Ontario-PPT Presentation

PPT Presentation

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The Port Lands Flood Protection and Enabling Infrastructure Project is transforming Toronto’s former industrial waterfront by creating a new river channel. Keller used diaphragm walls as temporary retaining structures and hydraulic cut-off walls in challenging ground conditions, including contaminated fill, peat and organic layers, cohesive soils, and shale and limestone bedrock. The groundwater level was approximately 1.5 metres below ground.<br /><br />The west plug wall served several roles in sequence: an 11.5-metre-deep dock wall for lake-side dredging, a 4.5-metre-high dam that enabled dry excavation of the river valley, and a load-bearing element supporting bridge off-loading. Buttress panels and T-shaped panels provided additional stiffness. Once the river channel was completed, the wall was removed.<br /><br />Diaphragm walls along the north and south riverbanks provided temporary support during excavation and will serve as permanent hydraulic cut-offs. Compared with the original secant-pile design, the diaphragm-wall solution reduced construction time from 8–10 months to about four months and was reported to cost 25% less. It also improved movement control and wall verticality while reducing construction joints. Overlapping hydro-mill panel joints were used to improve watertightness.<br /><br />The walls were monitored using in-place inclinometers, with real-time movement data and alerts available remotely. During service from 2020 to 2024, the west plug wall deflected 10–15 millimetres, withstood temperatures from −30°C to 30°C, and experienced limited water ingress. It was fully decommissioned in fall 2024.

Keywords

Port Lands Flood Protection

Toronto waterfront

diaphragm walls

hydraulic cut-off walls

river channel excavation

temporary retaining structures

contaminated fill

groundwater control

buttress panels

in-place inclinometers