The U.S. Environmental Protection Agency, the Wisconsin Department of Natural Resources and Superior Water, Light and Power Co. have awarded a $10.1 million contract to clean up contaminated sediment in Superior Bay.
The work centers on the C Street Slip, a 12-acre slip in the bay. Officials described it as the final phase of a $34 million project agreement to remove contaminated sediment and control sources of contamination in the St. Louis River Area of Concern.
Historic industrial use of the river and wastewater discharges left sediment contaminated with mercury, dioxins, polychlorinated biphenyls, polycyclic aromatic hydrocarbons and other toxins, according to the EPA. Manufactured gas plant waste dating back about 125 years is part of what crews will address in the slip.
Work is expected to begin in 2027. Crews plan to remove about 23,000 cubic yards of sediment with high levels of mercury and PAHs, dry it and transport it to an approved disposal facility, then place a thin layer of sand over the project area.
The St. Louis River was designated an Area of Concern in 1987 and is the second largest such area in the United States. Partners say 13 of 19 sediment remediation projects and 17 of 19 habitat restoration projects needed to remove the area from the list have been completed.
