Detroit banks on green infrastructure to rescue city from heavy rains

September 1, 2016

Detroit has a water problem. Or, more correctly, it has a stormwater problem.

Every time it rains, Detroit officials cross their fingers in hopes the city’s antiquated sewer system can handle the volume of stormwater that gets flushed into thousands of drains in parking lots and along city streets. In many cases, those drains are connected to sewer pipes that also carry sewage to the city’s wastewater treatment plant. When the system is overwhelmed with stormwater, which is happening with more frequency, the combined sewers end up discharging untreated sewage directly into local streams and rivers.

And during heavy rains, as residents have suffered through on at least three occasions this summer, basements also flood because they are hooked up to the same drains.

These combined sewer overflows discharge billions of gallons of untreated sewage into the Great Lakes each year, are the prime source of pollution in the Rouge River and are one of the main factors in the algae blooms impacting Lake Erie.

To alleviate the problem, you might say the city is turning to a natural ally. Rather than build more and bigger (and more expensive) pipes to capture the stormwater, the city is looking to nature to help out.
Fortunately for Detroit, the city controls large swaths of vacant land where these projects can be constructed. According to Gary Brown, director of the Detroit Water and Sewerage Department, the city directly controls about 40 percent of Detroit’s 138 square miles, giving city leaders a vast canvas for the new program, which began in earnest back in 2010.Under the direction of Mayor Mike Duggan’s office, the city is focusing on green infrastructure projects, including the elimination of impervious ground surfaces that don’t allow water to soak through, and constructing bioswales (similar to large vegetated ditches), wetlands, rain gardens and other methods that allow rain and snowmelt to more naturally filter into the ground, rather than running off into city sewers.

“We are jumping in feet first. We want to make this a hallmark of the mayor’s administration,” said Brown. “We don’t want to build anymore gray infrastructure.”

The move away from “gray” or traditional infrastructure – basically pipes – is definitely a change of philosophy for the city.

In fact, the original plan to deal with many of the combined sewer overflows (or CSOs) still in operation was to construct a massive underground tunnel 30-feet in diameter that would’ve had the ability to capture more than 200 million gallons of stormwater when it rains. It was also going to capture some of the remaining CSOs in Dearborn Heights and Redford Township, and be built along a seven-mile stretch of the Rouge River.

The project was supposed to be completed by 2015, and construction crews even began some of the preliminary work. However, in 2009, city officials scrapped the project because it was determined the estimated $1.2 billion price tag for the tunnel was just too costly for the city residents to absorb.

Instead, the city worked out a deal with the Michigan Department of Environmental Quality that allowed Detroit to shelve the tunnel project in favor of green and blue infrastructure strategies over the course of two decades. The work, much of it recommended through the Detroit Future City initiative, drew upon two of the city’s most daunting challenges – a shortage of money, and miles upon miles of vacant or abandoned land.

Click here to read the full article in Bridge.