Project Description
Project Scope
Soletanche Bachy Canada was appointed as the General Contractor to deliver an upstream cofferdam and trestle as part of the rehabilitation of the Nairn Falls Generating Station on the Spanish River in Northern Ontario.
Solution
Soletanche Bachy Canada designed and constructed a combined cofferdam and trestle system within a high-flow river environment characterized by steeply sloped, hard bedrock and rapidly changing water levels.
The solution included a combi-wall cofferdam, drilled pipe piles socketed into bedrock, rock anchors, and approx 130 m-long trestle complete with mechanical gates and multiple trestle bent assemblies. Precise installation and scribing of piles and gates were required to match the irregular bedrock profile and limit water infiltration.
To meet a strict regulatory deadline for in-water works, the team mobilized rapidly and implemented a 24/7 construction schedule. Specialized drilling methods and marine-based equipment minimized exposure to river conditions and allowed construction to progress safely and efficiently despite fluctuating flows and constrained working windows.
Sustainable development
The rehabilitation of the Nairn Falls Generating Station supports long-term renewable energy production and improved infrastructure reliability.
To protect the Spanish River ecosystem, Soletanche Bachy Canada implemented controlled drilling methods that allowed spoil recovery and treatment through sedimentation systems, preventing discharge into the watercourse. A site-specific environmental management plan guided construction activities, with continuous monitoring and additional controls applied to higher-risk operations.
Project Outcome
This project demonstrates our ability to deliver complex temporary works in fast-moving, environmentally sensitive river environments under strict regulatory timelines.
Through rapid mobilization, adaptive construction methods, and close coordination with stakeholders, Soletanche Bachy Canada delivered a reliable cofferdam and access system that enabled safe spillway demolition and reconstruction.
Key takeaways
- Successful execution in a high-flow river adjacent to an active spillway
- Reliable water control using a temporary cofferdam with operational gates
- On-time delivery ahead of in-water work restrictions
Industry Recognition
The Nairn Falls Generating Station project was featured in Piling Canada in an article titled
“Replacing Nairn Falls Generating Station and Spillway: Ensuring Sudbury and Northwestern Ontario Have Reliable Power for the Foreseeable Future.”
The article highlights the complexity of the temporary works, river-based construction challenges, and the critical role of the cofferdam and trestle in supporting spillway replacement.
