Project Details

Supplied and installed eighteen, 21m long, 500mm dia. stainless steel risers into holes drilled through overburden and rock on the bottom of Lake Ontario in 30m of water. The risers were then grouted into place to permit the tunnelling contractor (Strabag) to complete the outfall by connecting the bottom of the risers with the main tunnel. The tunnel is to be flooded and the diffuser caps removed

The marine trench required the excavation, transport and disposal of 50,000m3 of material, some of which was contaminated. Every pipe joint in the outfall was pumped full of grout in addition to the locking rings already on the pipes. Duck-bill diffusers were installed once the outfall passed its pressure-test.

The land-based portion of the work consisted of installing and dewatering sheet pile cofferdams/excavation protections to permit the excavation for and installation of the outfall through the shore-wall and into the river. The pipe/shore-wall interface was then sealed with concrete