Detroit, Michigan
The Detroit Riverwalk is located just south of the MacArthur Bridge to Belle Isle in Detroit, MI. Discharge from industry, stormwater outfalls, combined sewer overflows, and non-point pollution sources have contributed to the accumulation of contaminants within the sediments of the Detroit River. Contaminants within the sediments, primarily PAHs, are contributing factors to the designated Beneficial Use Impairments in the Detroit River Area of Concern.
Sevenson’s SOW included placement of a 67,500 SF active multi-layer sediment cap, including a 1-ft. chemical isolation layer utilizing AquaGate® and an armor layer; and habitat restoration of approximately 1 acre. The cap was installed to isolate PAH contaminants from the aquatic environment. Hydrographic surveys were completed prior to construction, during capping, and after construction to document final conditions. Sevenson installed approximately 1,750 linear feet of Siltdam Type 3 permeable 12-in. float, high flow 400-GPM adjustable curtains with equivalent quantity of 5-in. oil boom to control any sheens or turbidity created by capping activities. Subsurface debris was removed prior to cap placement in areas where the cap was to be installed.