Project Details

Supplied and installed 200m of 2250mm diameter concrete pressure pipe as an outfall for a stormwater retention/treatment structure. Installation was performed in the Detroit River during active shipping. The outfall pipe was installed through a steel sheet pile wall into an excavated trench on the river bottom which was subsequently backfilled with granular material and scour protection. The initial 50m offshore was excavated, and the pipe installed, on a 22.5 degree downward slope as the water depth increased the further offshore.

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