Implication of Detroit’s Bioswale on its Infrastructure Asset Management Planning

Detroit, Michigan has had a history of sewage overflow problems.

Last August it was hit by a mega-rainstorm that caused extreme flooding and released approximately ten billion gallons of raw sewage into the region’s waterways.

This and other factors have led to some experimentation in the city’s water infrastructure system, particularly to do with green infrastructure.

The newest of these little experiments is a small area dedicated to a bioswale.

Michigan Radio reports:

“So down on the west end, you’ll see a large, square enclosure. That’s actually a tree planter. Then we have sort of a long, rectangular box. That’s the actual bioswale.”

Jacqueline Bejma is executive director of the non-profit neighborhood development group LAND Inc.

She says the bioswale—that’s what the main contraption is called — will get filled up with a kind of “engineered soil” that drains really well.

“So it’ll fill up, the water will soak back down into the ground,” she says. “Whatever doesn’t will run through a pipe down the right of way towards the curb, and tie into the catch basin at the curb.”

The bioswale takes some strain off the conventional combined sewer system, she adds. Around half an inch to one inch of rainfall will go back into the ground instead of into the sewer system.”

“Bioswale” and other words like it may well become more common in the dictionary of the wastewater and water infrastructure asset management practitioners as more cities turn to green infrastructure in an effort to manage their overflow problems.

These changing methods of delivering services, and remediating problems can be examined in infrastructure asset management planning through:

• Levels of service – examining whether existing service levels and methods are delivering the required services, and looking at changing delivery mechanisms to meet required service levels
• Future Demand – examining changes in demand (for example permit requirements, public perception) and technology changes such as “bioswales” that change or modify infrastructure requirements to meet service levels
• Risk – examining the risks associated with existing service delivery mechanisms, and changing technologies, and determining the cost of the risks, and how they fit with the agreed agency risk policies

This analysis will then flow through to asset lifecycle management and expenditure projections.

As this brief examination of Detroit’s ‘bioswale’ test demonstrates, the field of infrastructure management and solutions to service delivery requirements is not static – changes are happening continuously.

Keeping up with these changes and optimizing service delivery solutions is part of the practice of infrastructure asset management.