Dredge in Many Flavors

An award-winning student project shows off dredged materials’ potential to restore habitats and reconnect the city.

Edison Park Site Proposal: A raised circulation system embraces a contained dredge production facility. Images courtesy of Matthew D. Moffitt.
Edison Park Site Proposal: A raised circulation system embraces a contained dredge production facility. Images courtesy of Matthew D. Moffitt.

The Penn State undergraduate Matthew Moffitt won the 2013 ASLA Student Award of Excellence in General Design by showing that not all dredge is created equal. Moffitt’s project, Dredge City: Sediment Catalysis, uses dredged material from the Maumee River, a tributary of Lake Erie, to restore a brownfield site, reestablish migratory bird stopovers, and connect urban and ecological systems, all in the context of an elegantly detailed park. By processing the material dredged from a shipping channel on the Maumee, Moffitt looked at Toledo, Ohio, the most heavily dredged port in the Great Lakes, and asked how one of the lake’s greatest polluters—the Maumee dumps a considerable amount of phosphorous into Lake Erie, causing algae blooms among other problems—can become a source of lifeblood for the city. We talked with Moffitt, who now works at Michael Van Valkenburgh Associates, about how he conceived the project and how dredge is becoming a hot research topic.

How did you become interested in dredging as a source of remediation?

The project originally began as a studio project during my senior year at Penn State. The studio origins were in Toledo, Ohio, so that’s how it all began. My professor, Sean Burkholder, is very knowledgeable about dredge and is often working in the greater Ohio region. There are several postindustrial sites in Toledo along the Maumee River, and the river feeds into the Western Basin of Lake Erie. We were given one of several sites along the river, and the site I chose was Edison Park. The challenges of the site included [combined sewer] outfall, dumping postindustrial material, and adjacency to one of the newer bridges and the downtown skyline.

His studio prompt was very inspiring, and from there I started making the connections between dredged material and the sediment itself, and from there it blossomed. The general goal for the studio was to use dredge or sediment from the shipping channel for a park design. The assignment was pretty broad, so we had a lot of room to use our imaginations.

How did you collect your data and use it to determine the design of your park?

What I did was look at the two overlapping scenarios: Incoming sediment from the channel and the rapidly declining health of Lake Erie. I documented every relative contributor to the failing health of Lake Erie in a large matrix. On the y-axis were factors contributing to health decline, and on the x-axis were intervals of time. By doing this I could see how dredge, over time, could implement greater ecologic change as well as increase the social perception of dredge as beneficial material.

A lot of my soil data was based off data and strategies from the Army Corps of Engineers. We called the movement of dredge a “pulse.” So the dredge would come into the site via barge over time, and different pulses of dredge were then dewatered using some of these Army Corps strategies and processes. Depending on the quality of the dredge material, it could then be used in different design scenarios.

The overall idea is that a brownfield site could stimulate growth in other areas of the city, and, over a period of time, to use the dredge material to improve urban and ecological health. A lot of this was thinking of ways to creatively design with this material rather than being limited by the engineering aspects of it.

What are some of the challenges you faced in developing this project?

When I was initially breaking down the dredge material, the research was somewhat unclear on what types of dredge are made when it’s being excavated from various locations. In other words, evaluating the levels of sand, silt, clay, water content, and inorganic pollutants. The dredged material contains each one of these elements, and the mix of each pulse ultimately informs the design decisions.

Dredge Container Typology: Dewater, phytoremediate, and apply admixtures.
Dredge Container Typology: Dewater, phytoremediate, and apply admixtures.

Among some of the project’s outcomes, you also focused on creating habitat for migratory shorebirds.

I had gone through hundred of factors in the matrix that were contributing to the decline of Lake Erie’s health and ecological areas that were suffering nearby or in adjacent areas, and what really kept surfacing in research were migratory birds. The north–south flyway goes right through the Great Lakes, and if you draw a line from wetlands through the Western Basin, you can assume these to be stopover sites for shorebirds and waterfowl. You can choose a point along that line to start rebuilding wetlands in the lake itself. I also saw this as a destination for residents of Toledo, and that’s where the spec site, Harborlands, came in. Each pulse of dredge material had a different quality or level of remediation that could contribute to the construction of these wetlands.

It’s unusual to see an undergraduate project take the Student Award of Excellence in General Design. What do you think made your project stand out against all the great graduate-level work out there?

There is a disconnect between theory and practice in landscape architecture, and most offices will hire someone for the practical application and skills or someone who can think critically about the greater issues in the profession. The main goal of my project was pushing the boundaries by fusing the practical and theoretical.

Where does the project go next? 

My professor is still very involved in the dredge sphere. He’s opening a competition in Toledo for the use of dredge material similar to the ways that I proposed in my project, and I hope to help with that a bit. Toledo is continuing to work on sites at the intersection of river and lake, and they expressed interest in using me as an aid in some of their upcoming projects. Although it’s not part of what I’m doing at MVVA, I definitely want to stay in touch with what happens with dredge.

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