Addressing Dioxin and Furan Contamination

Under the Great Lakes Legacy Act, and in partnership with the Minnesota Pollution Control Agency (MPCA) and an industry partner, the US Environmental Protection Agency’s (EPA) Great Lakes National Program Office requested construction services to address dioxin and furan contamination within Thomson Reservoir. The project, located in Carlton, Minnesota, was awarded to Brennan in the spring of 2024.

Our contract included placing a thin layer of amendment containing 10% powdered activated carbon (PAC) across the reservoir to address approximately 225,000 cubic yards of contaminated sediment. This remedy represents the largest remediation project of its kind implemented in the United States to date and is designed to reduce the bioavailability of toxins in surface sediments to macroinvertebrates, an essential food source for fish.

PFAS, often called “forever chemicals,” are at the center of one of today’s most complex environmental challenges. Used for decades in everything from manufacturing processes to firefighting foam applications, these persistent compounds are now found in soil, sediment, and waterways across the country. As research and regulations evolve, organizations are seeking trusted partners who can safely and effectively address contamination.

We'll explain PFAS, associated risks, and how Brennan is prepared with the expertise, technology, and experience needed to protect our shared environment.

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

Brennan embarked on a vital restoration project for the middle section of the Lake George Canal. The primary goal was to protect aquatic organisms by separating them from contaminated sediment through a multi-layer sediment cap.

Initial Site Challenges

Hydrographic surveys revealed areas of varying slope and stability as the first layer of cap material was placed over the canal bottom. These issues were attributed to soft underlying sediment within the canal footprint. The success of this project hinged on effective collaboration between Brennan and the U.S. Army Corps of Engineers (USACE) to address these types of challenges.

Our equipment safely navigates where barges can’t float and where ground equipment can’t trek. Brennan’s specialty amphibious trucks can float fully loaded with a 20-cubic yard payload or be configured to support geotechnical drilling equipment. See our equipment in action with this video! 

The US Environmental Protection Agency (EPA) and Minnesota Pollution Control Agency (MPCA) signed a project agreement to remediate contaminated sediment in the “ponds behind Erie Pier,” two ponds surrounded by shallow marsh wetlands in the St. Louis River Area of Concern (AOC).

The sediment was primarily contaminated with PCBs, PAHs, mercury, and chromium. Here's how we worked with stakeholders to clean up the sediment and the resulting impact of our work.

The Cuyahoga Improvement Project in Kent, OH, aims to improve future recreation experiences while protecting existing natural resources. The purpose of our work is to remove areas of petroleum-impacted soft sediments that were deposited decades ago from discontinued industrial practices upstream. 

Background on a Burning River

The Cuyahoga River has quite a history: a transportation route; a boundary; an origin for oil, rubber, and steel industries; a power source; and a dumping ground. The river was once 1 of the most polluted in the country. The Cuyahoga has caught fire at least 13 times since the 1860s.

February 6, 2023 — Specialty marine contractor J.F. Brennan Company, Inc. (Brennan) recently finalized the asset acquisition of the dredging and dewatering division of Infrastructure Alternatives, Inc. (IAI). The purchase brings dewatering, water treatment, and treatability testing services into the organization for the first time.

When you think “excavator,” images of digging dirt and rock on land may come to mind. However, that’s not the case for J.F. Brennan Company, Inc. (Brennan), a 100-year-old marine construction contractor out of La Crosse, Wisconsin. 

^{*adapted with consent from its original format in BREAKOUT Winter 2019: a Hitachi Construction & Mining Productions Publication.} 

This past year, we made another key asset purchase: the SHERP ATV (SHERP). In addition to our Diamondback Airboat, the SHERP solidifies our durability and efficiency in working throughout wetland and marshy areas.