Thursday, June 30, 2016

Worms to Help with Detroit’s Remaining CSOs

Who knew? Now Detroit can handle 95% of its combined sewer overflows! Worms will help with the remaining 5%.

On June 24, 2016, The Atlantic City Lab published an article by Jessica Leigh Hester titled “Detroit Is Turning Vacant Lots Into Sponges for Stormwater.” Hester reports (excerpts):

Detroit’s aged sewer system carries both sanitary sewage and stormwater. It overflows into creeks and rivers after heavy rains.

“Over the last two decades, the city has poured $1 billion into upgrading the system; now, its six retention basins and three treatment facilities can accommodate approximately 95 percent of the untreated overflow—an improvement, but an imperfect solution. ‘How do you get to the last 5 percent of the problem?’ asks Palencia Mobley, the deputy director of Detroit Water and Sewerage. ‘Spending another $1 billion or $2 billion doesn’t make a lot of economical sense.’ To bridge the gap, the city has pivoted to focus on green infrastructure …”

Image Courtesy of Joan Nassauer
Rendering, bio-retention garden, Warrendale neighborhood. (Courtesy of Joan Nassauer)

Small scale stormwater interventions may suffice in other, more crowded cities, but Detroit has plenty of room for larger projects.

“It’s a sprawling city, with vacant or buckling properties scattered across its 139 square miles. As of April 2016, 66,125 vacant parcels were held by the Detroit Land Bank Authority, which has received more than $100 million in federal funds to demolish blighted structures.”

“This spring and summer, researchers across the city are investigating the immediate and long-term ecological and sociological benefits of turning vacant land into stormwater basins topped with colorful plants.”

“Wade Rose, the vacant land restoration manager at the reforestation and farming organization the Greening of Detroit, described the process of remediating parcels that have been untended for decades. The houses that used to sit on top of them, Rose says, were demolished before the current protocols were put in place; they might have been bulldozed into the basement and sealed off.”

“The project deploys various techniques for soil remediation and water retention: a wildflower meadow; a tree stand, in which oak trees’ roots fracture compacted soils; rain gardens with deep depressions; and a treatment that deposits 100,000 worms at depths ranging from 2-6 feet, creating a network of tunnels that make space for storm water.”

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