Transit Tunnel Joint Sealing & Backwall Grouting — Calgary

The problem. Groundwater was entering a Calgary light rail transit tunnel through its joints — and in a working transit tunnel, water ingress doesn’t stay a nuisance: it was freezing into ice on the rail tracks. The repair had to seal the joints, displace the water sitting behind the tunnel walls, and be executed at track level around transit operations.

The repair. The crew worked a two-stage program directed by Eco Grouting Specialists: polyurethane resin was first injected to seal the joints and create confinement, then AV118 acrylamide grout — mixed on site in a mobile acrylamide grout plant — was injected behind the walls to fill the cavities and displace the water feeding the leaks. Acrylamide placement ran to a target of roughly 40 litres per port on an approximately 10-minute gel time, batch by batch, port by port along the tunnel.

The result. Joints sealed, backwall cavities filled, and the groundwater displaced from behind the lining — cutting off the ingress that had been icing the tracks. The project is also why a collapsible, custom-built acrylamide grout plant sits in our equipment inventory: built to mix and place solution grouts inside operating tunnels, and used again on tunnel expansion joint grouting at Queen’s Park in Toronto.