Reusing Dredged Material

Every year, two to three million cubic yards of sediment is scooped out of Great Lakes harbors and ports just for navigation purposes – not recreation. That’s enough to fill between 600 and 900 Olympic swimming pools.

Half of that material ends up in confined disposal facilities, or landfills designed for wet, heavy dredged sediment.

Much of the material dredged in Wisconsin ends up in those facilities because the state classifies dredged material as solid waste.

“That just adds additional restrictions, difficulties and testing we have to do for [reusing] dredged material,” said Gene Clark, coastal engineering specialist for University of Wisconsin Sea Grant.

While some dredged material does contain polluted material, Clark said most of it is washed off of land.

“We’re starting to really look at the material and realize a lot of this just came from the watershed,” Clark said. “It’s clean material and it can be used for a lot of uses.”

Clark is working with the Great Lakes Dredging team, a partnership of federal and state agencies, to promote the beneficial use of dredged material. Beneficial reuse is essentially recycling dredged sediment for use in other projects, such as aggregate in construction projects, sand for beach nourishment projects or to replace contaminated sediment in polluted places.

Recycling keeps the dredged material out of a landfill, which is a major regional concern since 80 percent of space in the 20 Great Lakes confined disposal facilities is used up and building new facilities is expensive.

“Beneficial use is motivated by that big volume,” said Dave Knight, who works at the Great Lakes Commission. “They’re essentially running out of places to put it.”

Knight said reuse could save money for small harbors that truck their dredged sediment to local landfills and cut costs for the projects where it’s eventually used.

The Village of Ephraim takes its dredged sediment to the village dump, where it’s available for people to take home and use for no charge. According to village administrator Charity Buhr, nobody has used the material so far.

Teaching people how to use dredged material is part of the Great Lakes Dredging Team’s mission.

“It’s truly an awareness issue,” Clark said. “[Reuse] is something we haven’t done as much in the past and we’re realizing how valuable this material can be. It takes a little bit of a startup education time before people start thinking [about reusing the material].”

But for that to happen easily or on a large scale, Knight said policy has to change.

“In the small harbors typical to Door County the sediment being removed is usually pretty clean, so I think that Wisconsin and some of the water policy folks that we’ve been working with are starting to recognize that, and hopefully being a little bit more open minded in how it can be used,” he said.

Jon Logan, a graduate student at the University of Wisconsin – Green Bay is studying beneficial reuse of dredged material. He’s working on his master’s thesis, and wants to write policy the state could adopt to make recycling dredged material easier.

“The policy that exists now in Wisconsin doesn’t really make it easy or lay things out, for managing dredged material,” Logan said. “There’s no real direct policy, it’s kind of lumped together with industrial byproducts.”

Reusing dredged material isn’t impossible in Wisconsin – The Port of Green Bay is using dredged sediment to restore islands that eroded away after the 1960s – but project managers have to prove reuse is safe on a case-by-case basis rather than following a policy already laid out.

“[Policy would] just give the ports more stability, they would know what to expect,” Logan said. “Even from a budget standpoint they could figure out what the best options are because they’d know ahead of time. They wouldn’t have to submit their plans to the DNR and wait for a response.”

Illinois, Indiana, Michigan, New York and Ohio allow ports to ship clean dredged material and place it in open water, which is allowed under the federal Clean Water Act but not Wisconsin law. Clark said the state is exploring the possibility of allowing open water placement.

Most other states don’t classify dredged material as solid waste as Wisconsin does, making it easier to allow it to be recycled for other projects.

Anything the state can do to make it easier to reuse dredged sediment is a good thing in Logan’s mind.

“In my opinion, everyone should be doing it,” Logan said. “Why are we putting organic material in a landfill? That doesn’t make sense to me, even if you’re talking about compostable organic material.”