Decades before water quality concerns led to environmental protection laws, maritime and industrial activities left a legacy of contaminated sediment throughout the Duluth-Superior harbor. These chemicals and heavy metals still remain today and continue to pose a threat to the public and aquatic life. Cleaning up remaining pollutants takes decades, as well, and progress is often measured one slip at a time.
Or, in this case, three slips. After researching options and gathering public input, the Minnesota Pollution Control Agency selected final remedies for Slip 3, Azcon/Duluth Seaway Port Authority Slip, and Slip C along the city’s waterfront.
At a combined estimated $9.9 million cost to complete the process from design through construction, the selected remedies now move into the design phase. Ultimately, construction will cover the contaminated sediment with approximately three feet of clean material and require no offsite disposal. Barring unforeseen design or funding delays, all three sites’ construction is expected to begin in 2018.
All cleanup options considered were weighed against four goals:
- minimize exposure to sediment contaminants that contribute to fish-consumption advisories.
- minimize exposure of aquatic organisms to contaminated sediments.
- preserve water depth to enable the current use of the slip.
- enhance deep-water aquatic habitat where possible.
In partnership with the U.S. Environmental Protection Agency and the U.S. Army Corps of Engineers, the MPCA will complete the remedial design at all three sites. This effort will include environmental review and permitting that will provide opportunities for additional public comment. Funding comes from the 2017 state’s bond funds and the federal Great Lakes Restoration Initiative.
Slip 3, Azcon/Duluth Seaway Port Authority Slip, and Slip C are located within the St. Louis River Area of Concern. This Area of Concern is one of 43 Great Lakes locations in the United States and Canada where historic shoreline alterations and industrial contamination caused impairments affecting wildlife habitat and aquatic life.
These three projects are part of a group of ten contaminated sediment sites whose cleanup will contribute to a healthier St. Louis River ecosystem. Completion also supports Area of Concern-wide goals of removing beneficial use impairments and eventually taking the Area of Concern designation off the St Louis River.