University of Michigan
OP-27: Rainwater Management

Site Sustainability is a broad topic that addresses specific local and regional environmental issues related to buildings, landscape, hardscape, and exterior building and site issues. Sustainable site practices at U-M include eliminating mowing in perimeter areas, utilizing Integrated Pest Management (IPM) techniques, removing invasive species from campus wood lots, employing alternative snow removal techniques, and administering a stormwater management and pollution prevention program. In an effort to enhance existing sustainable site practices, design guidelines have been revised and developed to coordinate with existing regulations and to recommend site specific strategies and Best Management Practices (BMPs). The design guidelines include recommendations regarding limiting paving, utilizing porous paving materials, an enhanced storm water management program, and information to assist in the selection of sustainable site materials. Also, additional guidelines for landscaping will be established which will focus on drought tolerant vegetation, native and non-invasive species, and enhanced IPM techniques. Examples of low impact development include: The C. S. Mott Children’s Hospital and Von Voigtlander Women’s Hospital: A vegetative roof to reduce storm water run-off, reduce heat island effect, and create a natural habitat. Storm water infrastructure (collection) and management to minimize run-off and avoid impact to neighboring Nichols Arboretum. Landscape Plan uses native plants and plant varieties acclimated to the Ann Arbor climate zone. http://www.umaec.umich.edu/wp-content/uploads/2013/11/MottSustain.pdf The Wall St East Parking Structure project: Porous pavements installed to reduce storm water runoff. Storm water will be mechanically and environmentally cleaned on-site prior to discharge. A large rain garden will be constructed in the east front yard of the parking structure to collect surface storm water runoff and to maximize on-site infiltration. Replenishing ground water on-site minimizes the potential for downstream flooding. Native and adapted plant materials that minimize the need for irrigation will be planted. http://www.umaec.umich.edu/ProjectSustainability/sustainabilityP00006281.pdf The East Quadrangle Dormitory renovation included replacement of non-porous material with porous pavement.

The Stormwater Management Program Plan (SWMPP) is prepared as a requirement of the University’s National Pollutant Discharge Elimination System (NPDES) Stormwater Discharge Permit. This permit is issued to the University of Michigan (UM) by the Michigan Department Environmental Quality (MDEQ). Our SWMPP describes measures, procedures and practices that UM will utilize to minimize the discharge of pollutants from campus into the stormwater drainage systems and adjacent receiving waters. U-M employees several Best Management Practices (BMP) designed to reduce storm water impact on the Huron River. Examples of BMPs include bioretention systems (i.e. raingardens), constructed wetlands, detention and retention basins, swales, green roofs, hydrodynamic separators and swirl concentrators, infiltration devices, level spreaders. And permeable and porous pavement.

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Porous (i.e. permeable) paving: There are several permeable pavement systems on campus including permeable asphalt, permeable pavement, and permeable pavers. Typically, a top layer of coarse material (permeable concrete, asphalt, or pavers) is laid over top of a crushed stone mix to allow for maximum infiltration of stormwater runoff. Rain gardens: Bioretention (i.e. raingardens)systems are depressed areas that capture and treat runoff. Most often bioretention includes a gravel layer surrounding an underdrain, a sandy media mix layer atop the gravel to encourage infiltration, vegetation to further increase infiltration and pollutant removal, and a mulch layer to keep in moisture and to prevent internal erosion. Space is left between the underdrain and the bottom of the bioretention basin to promote further storage and thus infiltration. There are several bioretention systems on campus. A great example is found right outside of the Dana Building on Central Campus Stone or vegetated swales: Grassed or vegetated swales are engineered ditches that promote infiltration while conveying stormwater runoff. These systems can be very simple ditches or very complex vegetated systems. A more complex vegetated swale that contains rock check-dam structures can be seen at the University of Michigan Arboretum.

Green roofs are engineered systems that incorporate special media and vegetation to maximize infiltration and evapotranspiration on rooftops. Most often, a green roof consists of an impermeable layer over a rooftop (to prevent leaks and structural damage), a drainage layer, a growing media layer, and a vegetation layer. The vegetation must be carefully selected for the local climate and must be able to endure various temperature extremes. Also, when selecting plants, remember that irrigation is discouraged and fertilization is a big no-no! Fertilizers, on or near a BMP, defeat the whole purpose of having the BMP. Green roof systems can be found on the Ross Business School, the Kresge Business Library, and the Mott Children’s Hospital and Von Voigtlander Women’s Hospital.

here are several permeable pavement systems on campus including permeable asphalt, permeable pavement, and permeable pavers. Typically, a top layer of coarse material (permeable concrete, asphalt, or pavers) is laid over top of a crushed stone mix to allow for maximum infiltration of stormwater runoff.

Bioretention (i.e. raingardens)systems are depressed areas that capture and treat runoff. Most often bioretention includes a gravel layer surrounding an underdrain, a sandy media mix layer atop the gravel to encourage infiltration, vegetation to further increase infiltration and pollutant removal, and a mulch layer to keep in moisture and to prevent internal erosion. Space is left between the underdrain and the bottom of the bioretention basin to promote further storage and thus infiltration. There are several bioretention systems on campus. A great example is found right outside of the Dana Building on Central Campus

Grassed or vegetated swales are engineered ditches that promote infiltration while conveying stormwater runoff. These systems can be very simple ditches or very complex vegetated systems. A more complex vegetated swale that contains rock check-dam structures can be seen at the University of Michigan Arboretum.