Milwaukee Finds A Fix For Stormwater Overflows: Abandoned Basements

Enlarge this image toggle caption Michael Sears/MCT/Landov Michael Sears/MCT/Landov

Some basement flooding could become happy occurrences, if more cities walk in the watery footsteps of Milwaukee.

As part of a new citywide sustainability plan and an attempt to reinvent itself as a "fresh coast" capital, Milwaukee is upgrading its water systems, and is researching options for tackling its chronic problems with stormwater management.

The city recently released a feasibility study that examines turning vacant basements into cisterns, preventing the untreated runoff from reaching the local rivers or Lake Michigan. The idea is the brainchild of Erick Shambarger, the deputy director of the city's Office of Environmental Sustainability.

After Milwaukee experienced major storms and subsequent flooding in 2008, 2009 and 2010, the city put together a Flooding Study Task Force, which included Shambarger.

A frequent topic of discussion was how to keep water out of people's basements. Milwaukee has a combined sewer system that collects both domestic waste and rainwater runoff, so when street flooding would overwhelm the sewer system, water and sewage would back up through the floor drains in people's basements.

While looking at a map of where the basement flooding was worst, Shambarger noticed that the location overlaps with the center of the city's foreclosure crisis. Hundreds of these foreclosed houses cannot be economically salvaged and are being razed by the city. Cue Shambarger's light bulb.

"If we are going to demolish the house anyway and there's going to be a vacant lot there, why not keep the basement portion of it?" he says. "Let's get water into those basements, and in the process keep other basements dry. We are making good use of a hole in the ground that somebody put there for us."

Shambarger and his team called the idea a "BaseTern" and trademarked the name on behalf of the city. Curtis Hulterstrum, the senior water resource engineer at HNTB Corp., examined multiple options for how the basements could be converted and the way BaseTerns would manage stormwater. Essentially, the basements will be used to immediately take the pressure off the sewage system by diverting and holding street and roof water "runoff" until the storm is over.

Water would flow into the structure, which would be covered with turf grass, via drains on top of the basement. It could flow out of the basement into the sewer system via the standard floor drain, or by adding multiple holes in the basement floor to allow some water to sink into the ground safely, or a combination of the two routes.

Kevin Patrick, a lawyer specializing in water issues, finds it "highly doubtful" that stormwater could be controlled in this manner, particularly in a way that is more economical than traditional stormwater solutions. But Hulterstrum says that it all depends on how you configure the outlet pipes, adding that costs will vary depending on the complexity of the BaseTern.

Shambarger says Milwaukee will begin measuring the idea's value by building a pilot BaseTern, hopefully by next summer, the city's rainy season. If Milwaukee finds success in the BaseTerns, it would be a big step up in the city's initiative to become a water technology hub.

The Fund for Lake Michigan paid for the feasibility study, and executive director Vicki Elkin says she'd be open to considering funding the pilot program as well. She says she hopes to learn not only how well the idea works, but whether it can be replicated in other areas of the city.

"What I'm hearing from engineers is that it's really place-dependent," she says.

David Waggonner, a water expert in New Orleans, says the idea sounds like a "worthy experiment." He adds, "I hope that it's a scale that will be replicable." Hulterstrum and Shambarger say the city has been getting a lot of interest surrounding the project, especially from other cities in the Great Lakes region.