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Coordination, Innovation, and Respect for the Environment
At the heart of Duluth, Minnesota—near Lake Superior—Brennan led a large-scale environmental remediation project at Munger Landing, removing historical contamination from over 34 acres of the St. Louis River. This multi-year effort addressed legacy pollutants including PCBs, mercury, dioxins, and furans through precision hydraulic dredging, sediment dewatering, water treatment, and the strategic placement of clean sand and habitat materials.
"The scale and scope of this project demanded constant coordination, innovation, and respect for the environment," says Project Manager Casey Evenson
In close coordination with GEI Consultants and under the oversight of a wide range of stakeholders—including the US EPA, the US Army Corps of Engineers, and the states of Minnesota and Wisconsin—Brennan executed a complex operation designed to restore the riverbed and support long-term environmental health.
Mobilization & Multi-State Coordination
Jurisdictional complexity was a central theme: “This project required aligning with the regulatory frameworks of 2 states, federal agencies, and the Army Corps,” says Amber Wilson, Environmental Compliance Manager at Brennan. “Transparency and collaboration were key to our success.”
Dredging & Debris Management
Targeted hydraulic dredging removed contaminated sediments from both shallow and deeper portions of the site. Crews navigated debris-laden zones and extremely shallow areas, overcoming challenges such as wood accumulation and tight working corridors. Material was pumped at high volumes to geotextile tubes, where solids were separated and water was treated on-site.
Water Treatment Excellence
As dredged material entered the dewatering field, water was separated and processed through a multi-stage treatment system. The plant featured multimedia filtration and granular activated carbon (GAC) to remove contaminants of concern. Sampling was conducted at multiple points throughout the treatment process to verify performance and ensure compliance with regulatory requirements.
Capping & Habitat Restoration
Once dredging was completed, Brennan applied a clean sand cover—6–12 inches thick—to the entire footprint, isolating any remaining contaminants and restoring the habitat. In some areas, Brennan placed a bio-medium cap to promote habitat recovery, using a blend of local material from nearby Perch Lake.
Crews installed over 16,000 feet of spreader piping, utilizing Brennan’s patented, proprietary Broadcast Capping System to distribute the cap material evenly over sensitive aquatic zones.
Environmental Impact & Legacy
Despite the project’s tight parameters and some of the strictest turbidity requirements Brennan has encountered, the team delivered on all performance metrics. The restored riverbed will benefit aquatic life, local ecosystems, and community recreation for generations to come.
“This project helps restore the river to the way it should be—especially in a beautiful community like Duluth,” says Wilson.
Funding provided by the United States Environmental Protection Agency, the Minnesota Pollution Control Agency, the Wisconsin Department of Natural Resources, and industry partners. Contract # 68HE0521D0002
For more project stories, visit our blog page. More videos from the Brennan team are available on our YouTube Channel.
Munger Landing Environmental Remediation Gallery
About J.F. Brennan Company
J.F. Brennan Company, Inc. (Brennan) is a family-owned marine construction firm specializing in environmental remediation, dam construction, commercial diving, harbor management, and submarine cable services. Working closely with public and private owners of water-based infrastructure since 1919, Brennan operates throughout the nation's coastal and inland waterways.
