Posted on October 16, 2023
The US Environmental Protection Agency (EPA) and Minnesota Pollution Control Agency (MPCA) signed a project agreement to remediate contaminated sediment in the “ponds behind Erie Pier,” two ponds surrounded by shallow marsh wetlands in the St. Louis River Area of Concern (AOC).
The sediment was primarily contaminated with PCBs, PAHs, mercury, and chromium. Here’s how we worked with stakeholders to clean up the sediment and the resulting impact of our work.
How we remediated sediment contaminated with PCBs, PAHs, mercury, and chromium:
Hired as the subcontractor of a joint venture, Brennan remediated 47,915 cubic yards of contaminated sediment in the two ponds near the Duluth-Superior Harbor. Our role consisted of dredging all contaminated sediment in the project area, dewatering the sediments on-site, and placing 6 inches of clean cap material over the dredged area.
The cleanup reduced toxins in the “benthic” or bottom-dwelling community in the ponds, reducing the contaminants in the macroinvertebrates that live in the pond sediment and provide an important food source for fish.
