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Got a defunct basement? Fill it with sand, plant a garden and control stormwater.

Dec 12, 2016

The Next Idea

My work in ecological design leads me to think about how the billions of dollars that governments must invest to replace and repair infrastructure can achieve more for American cities. Over the past several years I’ve focused my work on Detroit. Many cities, including Detroit, have some pipes more than a century old moving wastewater, stormwater, or drinking water underground. A handful of cities with industrial legacies, like Detroit, also have thousands of abandoned structures awaiting demolition. When a road is rebuilt, new pipes are laid, or when a building is demolished, I see the possibility of achieving many different, complementary benefits for residents and the environment at the same time.

I work to develop ways that investments in infrastructure also can achieve more attractive, healthy neighborhood landscapes. This is called “multifunctionality”. There is a special opportunity for multifunctionality in Detroit because the Detroit Water and Sewerage Department (DWSD) needs to remove stormwater from the combined sewer system at the same time as the city needs to demolish abandoned houses.

Traditionally, stormwater was moved underground in pipes beneath American cities. It was visible only after storms, when there might be puddles or flooding in the streets. A newer approach, called “green infrastructure,” or “GI,” is much more visible. GI aims to keep stormwater out of pipes and manage it close to where the rain falls – on the surface or in the ground using soils and plants. The visibility of GI creates potential for it to be designed to make neighborhoods attractive as well as to manage stormwater.

DWSD is using green infrastructure to complement its billion-dollar investment in combined sewer overflow facilities (gray infrastructure) to improve water quality in the Great Lakes. By 2029, it will invest $50 million for GI in the Upper Rouge River basin, which includes about a quarter of the city. Getting stormwater into the ground isn’t easy in Detroit because much of the city has clay soils, which are not as porous as sandy soils. But the city is moving a lot of soil in demolitions, which exposes the holes where basements used to be. My student team at the University of Michigan (U of M) suggested filling the basement holes of demolished houses with a porous soil that could hold stormwater. This is called bioretention.

Putting together the visible part of GI with the demolition opportunity to build bioretention, my research team, supported by the University of Michigan Water Center with a grant by the Erb Family Foundation, is collaborating with DWSD and the Detroit Land Bank Authority (DLBA) to build bioretention GI. We also are measuring how it is working to improve water quality and the quality of life for neighborhood residents.

The bioretention garden design concept that we developed pulls stormwater from city streets and holds it in porous soil below gardens located on former vacant lots. The gardens are designed to make more attractive, healthy neighborhoods. The first four of these bioretention gardens were constructed in the Warrendale neighborhood of Detroit last year, with engineering design by Tetra Tech, DWSD’s GI Program Manager, and construction management by Tooles Contracting.

To develop the design concepts for the gardens, I drew on my experience designing and testing GI in other cities, starting with a rainwater garden project designed for Maplewood, MN, and constructed in 1997. For that early GI project, I worked with neighborhood residents for two years, testing their preferences for different GI design ideas and aiming for a design that would be attractive to them. In my work, I’ve found there are certain landscape “cues to care” that many people want to see in their neighborhood. In Maplewood, we worked to find out exactly which cues to care people wanted in the rainwater gardens in their front yards, and how they wanted the vacant lot in their neighborhood to be used in a way that protected nearby residents’ privacy.

In Warrendale, leaders of the Cody Rouge Community Action Alliance and the Warrendale Community Organization have helped guide our work. We also surveyed all residents within 800 feet of the garden sites to learn about their preferences for the designs. As constructed, the bioretention gardens have many cues to care. They include either bollards or a low earthen mound facing the street to protect residents’ privacy. As our project continues, we will survey neighborhood residents again.

The bioretention gardens in Warrendale are relatively small – each garden covers just two former residential lots, but the potential to make lasting improvements to neighborhoods is large. Thinking about where vacant and abandoned properties are located throughout Detroit, and about the need to manage stormwater throughout the city, I see that the small pieces of individual properties and individual stormwater problems can be put together to make a much larger, greater whole – green infrastructure frameworks for whole neighborhoods.

There is enormous potential for Detroit residents to get attractive, walkable neighborhoods out of the investments that are being made in demolitions and stormwater management. Entering its next era as a great Great Lakes city, Detroit should aim for multifunctionality in its infrastructure investments.

The Next Idea is Michigan Radio's project devoted to new innovations and ideas that will change our state.

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