Lately there’s been lots of buzz about green infrastructure. Yet, I’ve found most people have no idea what it really is. I admit it wasn’t on our radar when we built our new home in 2008. Then we flooded badly in 2011, and again in 2013. Since then we’ve sought out a variety of options to better manage stormwater on our property. Last fall we installed Winnetka’s first permeable concrete driveway and some adjacent rain gardens, in addition to previously incorporating more trees, native plantings and rain barrels on our property. There’s good reason these best management practices are a growing trend regionally and across the country. As it stands, increasing impervious surfaces – roofs on buildings, driveways, streets and parking lots – prevent rain from naturally soaking into the ground. From connected downspouts and street sewers, stormwater is tunneled and discharged into local waterways, for Winnetka the Skokie Lagoons and to a lesser extend Lake Michigan (this is not the case for communities with a combined sewer for sewage and stormwater run-off). There are two major problems with this. Heavy storms can overburden sewer systems and lead to localized flooding. Also, stormwater run-off is heavily polluted and threatens the water quality of local waterways. In contrast, green infrastructure uses vegetation, soils, and natural processes to soak up rain where it falls. As stormwater infiltrates the ground, pollutants are removed. In addition to reducing the volume of stormwater run-off and protecting local waterways, green solutions also help clean the air, prevent erosion, replenish aquifers and provide wildlife habitat. Best of all, these nature-based solutions beautify neighborhoods. Green solutions work best when thoughtfully designed, cost-effective, quick-to-implement, easy to maintain and attractive. Fortunately, homeowners, businesses and public bodies can find a variety of wonderful examples locally, 30+ green solutions are shown below.
Nature-based stormwater solutions around town:
Rain gardens are slightly sunken areas filled with water-loving, long-rooted native flowers and grasses. They are designed to collect and absorb stormwater, often captured from rooftop downspouts, sump pump outlets or other impermeable surfaces pathways. A properly designed garden holds and soaks runoff, naturally filters the pollutants from the water, protects against erosion, and replenishes ground water supplies. Simple, low cost rain gardens can beautify a landscape, attract birds and butterflies, and require little maintenance once established. For more information, see Rain Gardens: A how-to manual for homeowners, the Illinois Rain Garden Initiative and the Rain Garden Network. Also learn more about flooding prevention strategies using rain gardens with the Center for Neighborhood Technology Wetrofit program.
Man-made wetlands are designed to reduce, detain and treat stormwater runoff. Water is stored in shallow vegetated pools that are designed to support wetland plants and simulate natural wetland ecosystems. Constructed wetlands have many of the same ecological functions as natural wetlands and are beneficial for flood control and water quality improvement.
Similar to rain gardens, bioswales are retention areas. A linear design helps regulate the flow of run-off from impervious surfaces nearby. Native vegetation slows and filters pollutants in the water as it infiltrates the soil. Bioswales are often used to manage and treat stormwater runoff from parking lots. Learn more about bioswales and where to visit them here.
The shallow roots of typical lawns do little to slow polluted runoff racing into street sewers and local waterways. Native plants and shrubs have large, porous roots which are better suited to absorb rain and moisture. For example, the clay-busting Red Switch Grass in our yard has roots that grow up to 10 feet long, which help drain the soil. Thanks to their beauty, hardiness and low maintenance, North Shore landscapes have been transitioning to native, deep-rooted perennial, grasses, shrubs and trees. Suited to our local soil, climate, and wet-to-dry conditions, native plants require no fertilizers or pesticides, less water and enrich the soil rather than deplete it. For more information and local resources on native plants, see The Midwestern Native Garden (Adelman/Schwartz) and wren’s Nurture Our Land.
Enhanced Tree Canopy
Preserving existing trees and planting new ones increases the natural canopy of leaves that catch rain drops before they hit the ground. Tree roots also break up tightly packed soil, increasing the amount of water absorbed by the ground. The larger and more appropriate tree, the more stormwater it can manage. Mature white swamp oaks, like the ones in my yard pictured below, are estimated to absorb 11,000 gallons of water per year. Especially when combined with rain gardens permeable pavement and other green practices, yard and street trees play an important role in reducing stormwater runoff.
Solid waterproof surface materials, such as blacktop asphalt, concrete or impervious pavers, send dirty runoff into street sewers and local waterways. Permeable hardscapes are designed to allow water to seep though. While providing the structural support of conventional pavement, it’s made of a porous surface and an underlying gravel layer for temporary storage and infiltration. When it comes to driveways, walkways, patios, parking lots, sidewalks and streets, there are many attractive and durable options. Permeable surfaces include porous asphalt, porous concrete, permeable interlocking pavers and turfstone. Gravel, wide-gapped stones, woodchips and mulch (assuming they are not covering asphalt) walk paths and driveways also allow varying degrees of infiltration. Learn more about the City of Chicago’s visionary green streets and alleys here.
Green roofs, or vegetated roofs, are composed of multiple layers including a waterproof membrane, subsurface drainage pipes, engineered planting soils and specially selected plants. Beyond collecting and divert rain water, they can reduce heating and cooling costs and last twice as long as a conventional roof. Green roofs can be installed on many types of roofs, from small slanting roofs to large, flat commercial roofs. Extensive roofs, covered with a thin layer of drought-tolerant vegetation, are less expensive, easier to convert and dont require watering. Intensive roofs are deeper, more elaborate garden landscapes that can expand a propertys green living space, but require more engineering, waterproofing, irrigation and maintenance. The good thing is, thanks to Chicagos acclaimed rooftop efforts, installation costs have been declining.
Stormwater can be collected and temporarily stored on-site with rain barrels or cisterns. This free water can be reused to benefit the property. Simple rain barrels can be used to water plants or wash cars. More sophisticated systems can be tied in with irrigation, waterfall ponds and toilet flushing. The Metropolitan Water Reclamation District (MWRD) of Greater Chicago sells rain barrels to Cook County homeowners for $58 available here. Learn more about the benefits of rain barrels at Recycle the Raindrops.
For more ideas on how to collect water on your property, prevent water pollution, reduce flooding and use less water in your daily life, visit the Going Green Matters fair on Sunday, March 9, 2014. In addition to presenting information about transportation, lawn and garden, food and farm, renewable energy and energy conservation by local businesses and non-profits – this year “Water Matters” is the theme of the Talk It Up session. This brainstorming exchange will be held with participants and representatives from the Natural Resources Defense Council, Center for Neighborhood Technology, Conservation Design Forum, Glenview Stormwater Task Force, Alliance for the Great Lakes, Metropolitan Water Reclamation District, and US EPA. A wonderful opportunity to learn more from water experts and share your thoughts.
Also see an NRDC case study of Chicago’s green infrastructure and the full national case study report Rooftop to Rivers, as well as 8 Shades of Green Infrastructure for other regional, national and international examples.
If you happen to live in Winnetka and prefer to see green infrastructure more comprehensively integrated in stormwater planning, as opposed to the Willow Tunnel plan, please see Winnetka’s Tunnel Vision before heading to the ballot on March 18.
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Thanks to everyone who contributed photos and details on their green improvements! Unfortunately, several wonderful rain garden and green roof projects are currently under snow, so they could not be shared here. I will add them in at a later date. This post is an update of wren’s Got Soaked? posted in 2012.