The sediment cleanup at the St. Louis River Interlake/Duluth Tar site is complete!

The St. Louis River Interlake/Duluth Tar site underwent a sediment cleanup under the Minnesota Pollution Control Agency's Superfund program from 2006-2010. A Great Lakes Legacy Act (GLLA) project was performed in 2010 to improve the cleanup's effectiveness. The project placed a cap under water in Slip 6 to cover a contaminated sediment disposal area from the Superfund project. The cap was made of an activated carbon mat and a layer of sand. The slim profile of the cap allowed for open water habitat and the growth of aquatic vegetation. The GLLA project helped the site achieve goals of the St. Louis River Area of Concern program.

Location

The St. Louis River forms the boundary between Minnesota and the northwest corner of Wisconsin. The SLR Interlake/Duluth Tar site is located in the St. Louis River Area of Concern in Duluth, MN. The project area is in Slip 6, four miles upstream of Lake Superior on the north bank of the river. The site is in the West Duluth neighborhood.

Cleanup Process

Sediment remediated: N/A (see note)
Contaminants: PAHs
Method: Cap
When: 2010
Partners: U. S. Environmental Protection Agency and XIK Corporation
Cost: $2.4 Million
Note: The cap was placed over an underwater confined disposal area for contaminated sediment from a Superfund project. Therefore, the volume of sediment remediated for this project is N/A to avoid double counting.

Long-term Benefits

• The cleanup builds upon a Superfund remedy that isolated contaminated sediment from the river. It enhances the protectiveness of the cap, adsorbing any contaminants from the disposal area, and allows wetland to form without having roots penetrate critical cap zones.
• The cleanup and restoration of the St. Louis River have contributed to community revitalization in Duluth. Learn about Duluth’s revitalization, including its economic growth and increased tourism.
  
  

The activated carbon mat is placed over the confined disposal area in Slip 6 to provide enhanced protection to aquatic life.

More Information

Documents and Resources
Great Lakes Areas of Concern: Six Strategies to Support Community Revitalization (PDF, 8p, 987KB) 2024
Duluth’s Revitalization: The St. Louis River Area of Concern (video, 5:20), 2022
​SLR Interlake/Duluth Tar Record of Decision (PDF, 109p, 375KB) August 2004

Stakeholders
City of Duluth
St. Louis River Alliance
Minnesota Pollution Control Agency St. Louis River
U. S. Environmental Protection Agency