Superior slips slated for cleanup
Apr. 15—SUPERIOR — Three slips in the Superior port are getting much-needed attention to address contamination from more than a century of industrial influences.
Planning is underway to remediate contaminated sediment in the Oil Barge Dock, General Mills and Tower Avenue slips in Superior's North End waterfront district. Sediment in these slips is contaminated with metals, mercury, organotin, polycyclic aromatic hydrocarbons and other compounds.
Work to remove nearly 190,000 cubic yards of contaminated sediment from the three slips is expected to get underway by 2026. The cleanup is part of the effort to delist the St. Louis River Area of Concern.
Historically, the land surrounding the slips has served as major storage and distribution sites for petroleum and coal.
"The improper waste disposal, industrial discharges, and even domestic and municipal wastewater was just discharged right into the waterways historically, and land uses over time have impacted the quality of water and what we see in the sediments of the sites," said Joe Graham, a project manager with the Wisconsin Department of Natural Resources.
Graham said the contaminated sediments impair uses, increase the cost of dredging and management of the dredge material, contaminate the fish with mercury and polychlorinated biphenyls, and impact the organisms that live at the bottom of the bays. The goal of the sediment remediation project is to remove the beneficial use impairments, he said.
"We do see some impacts or evidence of petroleum when we sample the sediments today," Graham said. "We frequently see sheen and we see indications of what we call nonaqueous phase liquids."
He said there has also been hull scraping and sanding of vessels, railroad activity and raw sewage discharges into the Tower Avenue slip from the late 1800s to the 1950s that have impacted the environment.
Contamination discovered through investigation since the 1990s does pose a risk to human health as well as the environment, Graham said. Each of the slips has a little bit different mix of contaminants, he said.
"Overall, the goal or the objective is to reduce the concentrations of constituents of concern to minimize or eliminate the risks," Graham said.
Working with AECOM, the DNR has analyzed options for dredging or capping the contaminated sediments. Dredging was the recommended alternative for each of the slips, Graham said. He said dredged material would be dewatered and landfilled.
Graham said the DNR will apply to the U.S. Environmental Protection Agency for Great Lakes Legacy Act funding to help pay for the $44 million remediation project for all three slips.
The project's goal is to improve water quality, reduce the pollutants affecting consumption of fish and wildlife, and improving the benthic community and wetlands in the bottom of the sediments, Graham said. It would also remove the restrictions and reduce the cost for dredging, he said.
"The EPA has studied this in other AOCs," Graham said. "... Making this investment in the waterfront really pays off in returns on that investment for the community and future development."
The public can weigh in on the plan as the DNR goes into the design phase for the project. Public comments will be accepted through June 7. To submit comments, search for "Superior Slips" at
or email
DNRRRSuperiorSlips@Wisconsin.gov
.
