DETROIT – Widespread flooding caused by heavy rains has developers and communities brainstorming to find solutions.
The city passed a stormwater ordinance in 2018 requiring large projects to manage stormwater through retention or detention methods.
“Retention means they’re disposing of the storm water on site somehow, usually through infiltration into the soil,” said Sam Smalley, deputy director at Detroit Water and Sewerage Department. “Detention means that they’re holding that water for a period of time before slowly releasing it back into the system.”
The Michigan Central development, a sprawling 30-acre site including the historic train station and Roosevelt Park, manages over half a million gallons of stormwater during a 100-year storm, according to Smalley.
This capacity helps prevent flooding by reducing the load on the city’s aging combined sewer system, which carries both sanitary and stormwater flows in the same pipes.
Changing precipitation patterns with more intense and frequent storms have made stormwater management critical.
“We’re getting more intense, frequent storms,” Smalley said. “We either want to slow the water down or, better yet, get it out of the system altogether.”
Michigan Central features multiple stormwater solutions, including underground storage tanks, rain gardens with native vegetation and permeable pavers that filter water rather than allowing runoff.
Jela Ellefson, development manager at Michigan Central, highlights the integration of art and function.
“We created an opportunity and a canvas for a piece of art,” she said. “We love creating opportunities where you layer different functions on top of each other.”
The site also includes large cisterns that capture rainwater from the parking garage roof at the Bagley Mobility Hub, storing about 75,000 gallons for irrigation use. These cisterns can be emptied before major storms to increase capacity and prevent basement flooding.
Michael Marks, a civil engineer who’s a partner and treasurer at Giffels Webster, notes the importance of managing stormwater to reduce strain on Detroit’s combined sewer system.
“It’s really important to be able to separate those water flows, so the sanitary can go directly into the combined sewer, but to take the storm water and detain it and slow it out, slow it down from hitting that combined sewer system,” he said. “That will reduce the strain on that existing storm, existing combined sewer system, and allow there to be more capacity for sanitary that will reduce basement flooding and other types of flooding events.”
The city has over 135 similar projects managing stormwater across more than 700 acres.
Smalley emphasized collaboration.
“Whether it’s aging infrastructure or more impervious area due to development redevelopment, we think it’s very important for not just Detroit but all surrounding communities to do their part in reducing the amount of load on the local and regional system,” he said. “We all play in the sandbox together – the GLWA regional collection and treatment system, so we all need to do our part to help reduce the load on it.”