Posted on February 07, 2012 9:05 AM
Metropolitan Water Reclamation District Approves Green Infrastructure for Stormwater Management
In January, the Metropolitan Water Reclamation District of Greater Chicago (MWRD) established new guidelines for implementing its Sewer Permit Ordinance (SPO) to allow the use of green infrastructure to manage stormwater runoff. Since the 1970s, the SPO has regulated drainage from developed properties in Cook County, requiring the use of detention basins or other facilities to slow down runoff during heavy rain storms to protect downstream property owners from flooding. Under the new guidelines, developers can employ “green infrastructure” techniques that mimic natural systems, such as devices that promote uptake of rainfall by plants or that allow water to infiltrate the soil. Since green infrastructure keeps part of the runoff onsite rather than conveying it offsite, using green infrastructure can now be counted toward part of the SPO’s required detention. On smaller sites, all of the detention can be provided through green infrastructure, while on larger sites a quarter of the detention requirement can be met this way. As a result, developers can now expect to save money on site infrastructure costs while simultaneously protecting water quality and maintaining the SPO’s flood control benefits.
In the Manage and Conserve Energy and Water Resources section of GO TO 2040, the plan noted the benefits of using green infrastructure to manage stormwater and recommended removing barriers to its use. One common obstacle is the requirement to provide just as much detention whether or not green infrastructure is used on a site, which eliminates any financial incentive to use green infrastructure. The MWRD has now reduced a significant barrier to its use in Cook County.