In November, the Detroit Water and Sewerage Department released guides to help customers understand its stormwater drainage fees, including ways to implement green infrastructure to
gain credits toward reducing those fees.
The drainage fee had never before been charged to owners of approximately 22,000 parcels in the city, who began receiving letters from the agency in August, according to the Detroit News. DWSD is transitioning to a uniform system in which each customer is charged a fee based on the area of the impervious surface, such as concrete, pavement, and rooftop, located on the parcel.
At a workshop for Nonresidential Property Owners on Nov. 9 at SEMCOG, customers were given the basics of how the fee will work and how they can use stormwater management practices, including green infrastructure, to reduce their fee. A second session will be held Dec. 14. The presentation can be viewed
here.
"It's highly critical that our customers understand the drainage charge, what it pays for and the credit system we are developing," DWSD deputy director Palencia Mobley told an audience of nearly 100 people. "Detroit has not done a good job over the years at communicating to customers what they pay for. This administration is serious about changing that."
The presentation began with an explanation of the city's combined sewer overflow (CSO system) which combines sewage and stormwater runoff. EPA regulations have forced investments in CSO infrastructure, such as the Conner Creek facility on Detroit's lower east side, to prevent overflows from the system into area waterways such as the Detroit River and the Rouge River. The new drainage fee will go toward funding operations and maintenance of this infrastructure.
Each parcel owner is receiving an initial assessment based on the area of imperviousness according to the following formula:
Drainage charge = Total impervious surface area X Impervious acre per month (dollars per acre per month)
The fee is currently set at $750 per impervious acre. For example, a four-acre parcel with two acres of a parking lot would be charged $1500 per month. The new fees will be phased in over the next two years, starting with industrial and commercial properties in early 2017, followed by tax-exempt and residential properties later next year and finally faith-based properties starting in 2018.
Impervious area is evaluated using remote sensing technology integrated with the city's Geographic Information System (GIS). Customers can view their assessment using the city's Parcel Viewer tool. Because remote sensing data may contain errors, customers have the opportunity to contest and adjust their assessments.
Customers also have the opportunity to reduce their fee by taking actions on their property to reduce the peak flow and volume of stormwater runoff.
Volume credits help reduce the overall burden to the system by Infiltrating, evaporating, and reusing water. Green infrastructure treatments that achieve volume reduction include redirecting downspouts to pervious areas onsite, green roofs and water harvesting. Peak flow credits help slow the transport of water into the system, reducing the chances of overwhelming the system and reducing the risk of flooding. Green infrastructure treatments that achieve volume reduction include detention basins and subsurface storage. Several types of green infrastructure, including bioretention, permeable pavers and water harvesting, can achieve both volume and peak flow credits.
Depending on the mix of treatments applied and existing site conditions, customers may be able to gain enough credits to reduce their assessments by as much as 80 percent.
More information can be found at DWSD's drainage website.
This story is part of a series on measuring on the role of green infrastructure projects in Detroit's redevelopment. Support for this series is provided by the Erb Family Foundation to Greening of Detroit, Model D, and The Nature Conservancy. Read more articles from the series here.
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