Experts weigh in on how to fix and pay for Detroit’s flooding problems

 The Great Lakes Water Authority has said it could take anywhere $5 billion to $20 billion to upgrade the regional stormwater system enough to reduce basement flooding.

In 1972, Milwaukee had the good fortune to be sued by the state of Illinois. At the time, Milwaukee and several nearby cities were sending an estimated 200 million gallons annually of combined sewer overflow (CSO) – a mix of untreated or partially treated sewage and stormwater – into Lake Michigan during heavy rains.

The fortunate part was that the lawsuit came at a time when abundant federal funds were available to pay for water infrastructure. And so 55 percent of Milwaukee’s so-called “Deep Tunnel” – a series of underground retention basins that hold untreated sewage and keep it from flowing into the lake – was covered by the federal government. The project was rolled out in three phases, starting in 1993; it’s been referred to as the “backbone” of the city’s now widely-praised sewer system. The deep tunnel can sequester 520 million gallons of water, enough to fill up the U.S. Capitol Rotunda 53 times.

Milwaukee continues to deal with heavy rainstorms and flooding, similar to other Great Lakes cities where the climate crisis is increasing the intensity and volume of rainfall. But the tunnel made a substantial difference. 

“It brought us down from having 50 to 60 [sewage] overflows a year to two or three,” Breanne Plier, manager of sustainability at the Milwaukee Metropolitan Sewerage District (MMSD) told Planet Detroit. 

Milwaukee plans to reinforce its stormwater capacity by adding 740 million additional gallons worth of storage in the form of green stormwater infrastructure (GSI) – including tree planting and bioretention swales or vegetated depressions that catch rainwater and slowly release it back into the groundwater or storm sewers–as part of its “2035 Vision.”

Milwaukee’s experience could offer a roadmap for Detroit, according to Sanjiv K. Sinha, a senior vice president at the consulting firm Environmental Consulting & Technology. “By rolling together green infrastructure and traditional stormwater infrastructure quickly, [Detroit] could tap into economies of scale that reduce the overall cost [of infrastructure projects],” Sinha told Planet Detroit.  

Detroit suffered its second “500-year flood” in a decade on June 26, 2021 when parts of the metro area received more than six inches of rain in a single night, backing up sewers and sending water and sewage into thousands of basements. Although it’s impossible to know how many gallons of water backed up from overloaded sewer systems and streets into homes, roughly 10 billion gallons of sewage flowed into local waterways following the storm.

Like Milwaukee, Metro Detroit has already spent a lot of money to address its CSO problem. A study commissioned by the Erb Family Foundation found that the region invested more than $2 billion to build nine CSO facilities that collectively treat 97% of wet weather events. The number of uncontrolled CSOs in the region has declined from 310 to 76 annually since 1988.

But with an accelerating climate crisis bringing more intense storms and flooding to eastern and midwestern cities, the region will need to act quickly to mitigate future disasters. A flooded basement can cost a homeowner tens of thousands of dollars, and at least 80,000 households called the city’s flood complaint center last June.

Billions of gallons, billions of dollars

Staving off further economic damage from flooding could require adding millions, if not billions, of gallons of additional capacity to the Great Lakes Water Authority (GLWA)’s regional system.  “You’ve got to match the spatial scale of the solution to the spatial scale of the problem,” said Bill Shuster, a professor and chair of civil and environmental engineering at Wayne State University.

Shuster notes that over the last few decades the regional sewer system has expanded its service area without adding sufficient capacity, while rising levels in the Great Lakes and broken pipes stressed existing infrastructure.  

GLWA, which oversees much of the region’s sewer and water treatment infrastructure including the troubled Conner Creek Pump Station and Freud pumping stations whose partial failure contributed to the June flooding, has said it could take anywhere $5 billion to $20 billion to upgrade the regional stormwater system enough to reduce basement flooding. A GLWA statement emailed to Planet Detroit said the agency plans to invest $3.4 billion in water and wastewater improvements over the next ten years, which includes rebuilding the Conner Creek Pump Station and replacing the Freud station. 

City solutions

Detroit Mayor Mike Duggan has proposed expanding sewer capacity on the far east and west sides of the city to avoid basement flooding by sending combined sewage directly into the Detroit River during major storms as opposed to the city’s sewer system. But that would come at the expense of surface water quality and potentially drinking water quality.

And DWSD Director Gary Brown suggested separating sanitary and storm sewers, which could cost around $2.2 billion.

But while sewer separation might reduce sewage backups in basements, Shuster said there’s no guarantee it would totally prevent them unless significant capacity to the overall system is added. Another problem is “rainfall-derived inflow and infiltration,” a term that refers to stormwater moving into aging, leaky pipes and creating backups.

As a short-term fix, the city is investing in backflow valves to prevent basement backups. The department is piloting a cost-sharing program in affected neighborhoods that will pay homeowners $6,000 per household to install the devices.

Jefferson Chalmers resident Blake Grannum is considering installing the valve after experiencing multiple floods in the past decade. On June 26, she once again had several feet of water in her basement, the largest among several backups she experienced last summer.

“We’re constantly cleaning,” Grannum said. “Every single time you flood, you have to spend money, not just replacing the things that you’ve lost, but having to get it cleaned so that you can at least breathe properly.”

Blake Grannum in her Jefferson Chalmers backyard. Photo by Nick Hagen.

But Shuster cautions that backflow valves aren’t a cure-all for basement flooding. “You’re just sending it to your neighbor’s basement,” he said. “It’s also uncertain whether your pipe is going to be able to handle it without bursting.” 

Is green infrastructure part of the solution?

Shuster says building more Deep-Tunnel-style reservoir projects across the region is likely necessary. GLWA, DWSD and the Michigan Department of Transportation recently proposed such a tunnel to divert water from seven miles of I-94 in Detroit. It’s the sort of project that could significantly reduce overall pressure on the combined sewer system. 

But Sinha emphasizes green stormwater infrastructure (GSI) interventions that can also offer benefits beyond just storing stormwater.  “We do need to focus on green aspects of the solutions because they are a smarter play from a climate adaptation standpoint,” he said. The EPA lists a number of climate benefits for green infrastructure, including reducing city heat islands, using less energy for pumping water, and decreasing ozone pollution, something that could become more prevalent with warmer temperatures.

DWSD has already built GSI that can handle 61 million gallons of water annually, including bioretention ponds on Oakman Boulevard on the west side of Detroit that can sequester 37 million gallons of stormwater.

And a partnership between DWSD, GLWA, and Oakland County will construct new storm sewers and green infrastructure on Detroit’s west side to eliminate around 48 million gallons of sewage and stormwater that would otherwise go into the Rouge River. 

But as impressive as these efforts are, they represent just a fraction of the capacity needed to manage the billions of gallons of stormwater the area likely experienced on June 26. 

Sinha said that the estimated 20 square miles of vacant land in Detroit present an opportunity for cost-effective GSI. But Shuster believes much of Detroit’s vacant land is already functioning as “passive green infrastructure,” absorbing rainfall and taking pressure off the regional sewer system. “We’ve documented that [open space] is basically [absorbing] 90% of all warm-season precipitation” in the city, he said. That means that in some areas the advantages of installing more green infrastructure may offer only a marginal improvement over the neglect that has allowed weeds and tall trees to flourish and storm grates to remain blocked.

The Erb Family Foundation study notes that GSI solutions are most effective when built in the upstream portions of drainage areas (also known as sewersheds). The study also pointed out that building up the city’s urban tree canopy may offer a more cost-effective remedy than solutions like constructed wetlands and bioswales. A hydrologic analysis showed that increasing the city’s tree canopy from its current level of 23.6% up to 30% could manage more than two billion gallons of water.

Paying for it

Michigan State Sen. Jeff Irwin (D-Ann Arbor) has been working to fund water infrastructure through a proposed $5 million ”climate resilience plan” to include $1.5 billion for water and sewer infrastructure.  He said residents will pay the cost for flooding either by funding their own cleanups or by investing in infrastructure.

“Every single person who’s throwing thousands of dollars worth of stuff in their basement, who has to deal with that muck, and who maybe got their car stuck on I-94, those are the people we should be asking about how costly is it for us to ignore these problems,” Irwin said.

Irwin said that while his bill isn’t nearly enough money to fix metro Detroit’s sewer problems, it would provide entities like DWSD and GLWA with additional financing to make investments in regional systems. For context, Milwaukee has invested $3 billion in its Water Pollution Abatement Program between the late 1970s and early 1990s, which included $1 billion for the Deep Tunnel. Another $1 billion was invested in the 2000s to further reduce CSOs and basement flooding.

Grant programs dedicated to GSI include the Southeast Michigan Stormwater Resilience Fund, which awards approximately $1.2 million in funds for projects in seven counties in southeast Michigan. And the federal Great Lakes Restoration Initiative, launched in 2010, funds Great Lakes restoration projects across the Great Lakes basin, including some GSI projects. 

Meanwhile, a state bill to appropriate $3.3 billion in funding for water infrastructure improvements passed the Michigan Senate in December and is currently awaiting action in the Michigan House. Editor’s update (3/24/22): On Wednesday, March 23, the FY 2021-22 Supplemental Appropriations Bill passed out of the House with more than $2.5 billion dedicated for water infrastructure improvements. The overall bill, which includes spending on other issues, draws on $3.1 billion in federal pandemic relief funds.

And President Biden signed a $1.2 billion bipartisan infrastructure bill last November, $10 billion of which is headed for Michigan. Of that, $1.3 billion is targeted for water infrastructure. 

Sinha says financing for stormwater improvements can include a combination of federal infrastructure dollars and municipal environmental impact bonds (EIBs) that can be used to fund climate adaptation. He points to Buffalo, which recently issued a $49 million EIB to build green infrastructure and CSO storage. 

However, paying back such bonds may be a challenge for Detroiters, who already pay more than 3 percent of their annual income for water service – a common benchmark to measure affordability. Most of this covers sewer and drainage fees. The region will likely need diverse funding sources to arrive at a workable solution, as well as interventions tailored to neighborhoods like the east and west sides of Detroit, Grosse Pointe Shores, and Dearborn that experienced the most flooding. 

All of this may not mean much in the short-term for Grannum in Jefferson Chalmers, who says that talk is no longer enough when it comes to protecting her neighborhood, where another spring could mean more flooding, as it did in 2016, 2019, 2020 and 2021.

“People here don’t have any patience,” she said about those in her neighborhood. “How much more do we have to talk about this?”


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