Shipping channels need to be dredged, but where does the material go?

by Christina Dierkes, Ohio Sea Grant Communications 

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Dredging shipping channels is an unavoidable part of harbor maintenance across the Great Lakes. In Toledo, Ohio, the Army Corps of Engineers removes about one million cubic yards of sediment from the Maumee River each year, washed downstream by heavy rainstorms and agricultural runoff. But once the sediment is removed from the shipping channel, where does it go?

So far, there are two options: storage in containment facilities, or open lake dumping. However, containment facilities are expensive, take up valuable space, and don’t look particularly attractive. And open lake dumping could add fertilizer attached to sediment particles to an already fragile lake ecosystem, potentially worsening harmful algal blooms.

Dr. Elizabeth Dayton, Research Scientist in Ohio State University’s School of Environment & Natural Resources, is working to provide a third option: beneficial reuse of up to 100,000 cubic yards of dredge material per year. Funded by Ohio Sea Grant, she is collaborating with soil blenders along the Lake Erie shore to create custom soil blends for construction and landscaping that incorporate dredged material as a main component.

“We’ve recently completed a characterization scheme for soil blends, based on chemical and physical properties,” Dayton explains. “That allows us to come up with a tailored soil blend, where someone can tell us approximately what they want in the soil, and we can help them create a recipe that will meet their needs. And of course we’re trying to have dredged material be the primary ingredient.”

The first customers for such a custom soil blend are the City of Toledo and the Toledo Land Bank, who commissioned a blend for remediation of building sites where abandoned homes are being demolished. Dayton and her team created a blend of 80% dredged material and 20% leaf compost from the city’s yard waste collection, which matches the desired soil specification and could be used on more than 300 sites throughout the city.

Dayton is also working on fill material for the Cherry Street Legacy Project in central Toledo, an effort to create a stronger and safer neighborhood surrounding Mercy St. Vincent Medical Center. The project requires a soil blend that is both appropriate for filling demolished building lots after potentially lead-contaminated soil is removed, and for turning the lots into green space or side yards for neighboring homes.

Karen Rogalski, who coordinates the project as part of the hospital’s community health efforts, appreciates the opportunity to use local resources in her work.

“Our mission at the hospital is to improve the health of our community,” she says. “And we had a great opportunity to use resources such as dredging material and leaf collection and make a product that can improve the health and beauty of the community and will help us create a sustainable environment.”