Located in Duluth, Minnesota, the St. Louis River estuary and its tributaries comprise a U.S. Environmental Protection Agency (EPA) Great Lakes Area of Concern (AOC), including Spirit Lake, a large open water portion of the river at a former manufacturing site. In 2011, a confidential client hired Barr to assist with addressing state regulator concerns regarding the site’s aquatic portions. Barr led sediment investigations to update the conceptual site model, assess physical and chemical sediment characteristics, groundwater-surface water interaction, and hydrodynamic conditions to inform remedial design strategies.
We recommended a partnership with the EPA’s Great Lakes National Program Office (GLNPO) under the Great Lakes Legacy Act (GLLA) to implement the design. When the EPA joined the project through a GLLA cost-sharing agreement, one of its national consultants, EA Engineering Science and Technology, Inc., PBC, asked Barr to join the design team. Our key activities included designing sediment remediation for the former coke-settling basin, involving reshaping a historical earthen dam, and developing restoration plans for a meandering stream.
Remedial construction concluded in 2024, a major step toward delisting the St. Louis River as an AOC. The project remediated 1.3 million cubic yards of impacted material, restored 200-plus acres of aquatic habitat, dredged 460,000 cubic yards of sediment and soil, and installed 96 acres of subaqueous caps. Additional work included two on-site confined disposal facilities (CDFs), extensive habitat plantings, realignment of 3,500 feet of stream channel, 6,400 feet of shoreline protection, and creation of a 14-acre sheltered bay for fish-spawning habitat.
