Green Infrastructure Mimics Nature to Fight Stormwater

By Marilyn Witney, ICN Pro, AMG
Marketing Director, Midwest Ecological Landscape Alliance
www.melaweb.org

Ball_smallWhen astronomers search for life beyond our earth, they look for the one thing vital to all life as we know it: water. But this resource, the only one that drops right from the sky to our doorstep, free of charge, is not limitless. Just ask anyone in California or Texas this past summer.

Here in Chicago, it seems that most of the time we have way too much water. Last year, we experienced historic rain events. In part due to climate change, this is becoming the new normal. Storms are more frequent, more intense and less predictable. This season has already had above average precipitation, climbing again toward historic levels. In August, numerous areas received more than the normal rain expected for the entire month in just one day . All of this has added up to millions of dollars in damage for municipalities and landowners, along with heartache and loss because of flood-damaged homes, businesses and recreation areas.

New methods to control stormwater and mitigate flooding, and the resulting damage, are needed. The newest of these, Green Infrastructure Best Management Practices (GI BMPs), copy Mother Nature by increasing the impact of the eco-system services she already has in place, but have been covered over or removed by increasing urban development like roof tops, parking lots, roadways, sidewalks and lawns. Professionals in all disciplines are starting to learn more about these green BMPs and utilize them successfully to augment or replace traditional gray infrastructure that merely moves the problem downstream.

“For the future, the key to healthier waterways and more sustainable communities is to capture water where it falls, harvesting it for reuse or allowing its percolation through the soil,” said Mike Curry, Principal of GreenSite, Inc. “This movement through the soil filters and cleans the water so it can eventually replenish our aquifers, while at the same time reducing volume to a rate our existing systems can handle.”

Curry is also President of Midwest Ecological Landscape Alliance (MELA), a not for profit that drives demand for sustainability in the built environment by providing resources and education to their diverse membership of green industry professionals. “It’s also essential that green professionals from all disciplines come together early in each and every project,” Curry said, “so that development of design, installation and maintenance can work together to make green infrastructure successful.” MELA is hosting a green infrastructure event in October with the goal of bringing these professionals together for a serious and informative discussion.

shore_smallDebra Shore, a Commissioner at the Metropolitan Water Reclamation District of Greater Chicago (MWRD) will keynote MELA’s event. Shore took office in 2006, and over the past eight years she has seen the MWRD change, “shifting from a waste treatment to a resource recovery utility.” According to Shore, “Green infrastructure can peel back the concrete skin created by developing our cities, and provide more opportunities for land to absorb water and give our sewers a chance to work.”

It’s not just the quantity of precipitation that’s falling that is overwhelming the system. It’s how fast it’s falling. Shore reported that this summer, in the period between June 30 and August 24, some municipalities received between a third to almost half of the total rainfall that they typically record on average . And that’s not spread out evenly over those fifty-six days, but is concentrated in a handful of intense rain events.

In May of this year, the MWRD’s Watershed Management Ordinance for Cook County took effect setting minimum standards for retention and detention of rain on site. Additionally, the ordinance should help to reduce future flooding by requiring capture of water where it falls, in part using green infrastructure techniques. Recent legislation passed by the State of Illinois has also made it easier to use and get funding for green infrastructure best management practices. “Green infrastructure that captures rain where it falls and keeps it out of the sewers won’t solve all our storm problems, but it can help,” said Shore. “By absorbing more rain, green roofs, permeable pavement, vegetated swales at roadsides, rain gardens and rain barrels can all slow the flow of rain into the sewers, giving them added capacity to handle stormwater. These techniques, if implemented widely, can effectively turn a four-inch rainstorm into the equivalent of two inches.”

One of the challenges with green infrastructure practices is a lack of performance data over the long term. “We’re doing that,” Shore said. “Over time, the database has been growing so that we can come up with some innovative solutions that provide an intersection between green and gray infrastructure, along with empirical data that supports installations that will last for decades.”

bioswale_smallOne project that has stood the test of time is the Visitor Center Parking Lot at the Morton Arboretum. Completed in 2004, the renovated parking lot holds 500 cars and eleven buses. Pioneers in utilizing Green Infrastructure BMPs, the Arboretum worked with civil engineers and landscape architects who created the environmentally progressive design using interlocking, permeable paving blocks with gaps at the corners filled with fine gravel. The permeable blocks and gravel act as a filtration system for rainwater and melting snow so that pollutants can be removed or broken down before runoff reaches other water sources. Below the pavers is a four-foot gravel bed that filters stormwater and slows its progress through the watershed. Water is also collected in bioswales throughout the lot. Plants within the bioswales biologically filter contaminates in the water, assisted by mechanical filtering through the gravel bed underneath.

“The storm sewers seldom contain any water at all,” said Susan Jacobson, FASLA, the Arboretum’s landscape architect. “Water does not appear to be flowing off the lot, but is being absorbed into the ground water even more efficiently than expected .” She continued by saying that in the past ten years, virtually no maintenance has been required on the pavers versus an asphalt lot that would have required regular sealing, patching and re-striping. A research analysis of the project, which is part of a multi-component green infrastructure system that was designed and installed in 2005, will be published in the next few months.

Ball Horticultural in West Chicago, another MELA member, had a vision to transform their headquarters into a showcase that mimics their corporate commitment to sustainable solutions. They partnered with WRD Environmental, a MELA founding member and a firm that, since 1997, works with organizations committed to sustainable development to help them realize their vision. Together they reinvented the Ball headquarters’ 1960s landscape two years ago into a natural area where staff can hold meetings, relax or harvest fruits and flowers.

The award-winning design features a variety of GI BMPs including five large rain gardens that are tucked into the ambient landscape and are underlain with large catchments of open-graded rock. The rain gardens are not connected to the city system, so every drop of water that enters is absorbed by plants or infiltrated into the ground. Jay Womack, WRD’s Director of Design, explained, “Bioswales also move through the landscape, taking overflow from adjacent sidewalks to the site’s detention basin. While a stormwater management tool, the swales add an aesthetic element as well. They are planted with native grasses that mimic water flowing through a creek bed.” Womack reports that the clean water that does enter the detention basin is now helping to sustain wetland plants in the bottom, adding another ecosystem and additional biodiversity to the landscape.

With the Ball headquarters building nearly two feet lower than the adjacent road in many places, and situated in an area with serious flooding issues, stormwater management was high on the agenda. In particular, Ball sought to capture the stormwater flowing toward the building from the new sidewalks and ambient landscape, and redirect it away from building entrances. WRD used a combination of green infrastructure techniques to create a native landscape interspersed with rain gardens and cross-pitched sidewalks that move water away from the building in a safe and environmentally sensitive way.

pavers_smallAccording to Ball’s Manager of Innovations, Bill Doeckel, “After the severe spring 2013 storms, the detention basin was completely dry, but the rain gardens were full … an obvious sign that the best management practices are working!” In fact, over the past two years, the detention basin, required by the city, is needed only on rare occasions—so much so that the company has successfully naturalized the entire basin into a native prairie.

In 1910, President Teddy Roosevelt said, “A civilized people should be able to dispose of sewage in a better way than by putting it in the drinking water.” Over one hundred years later, in severe storms when the amount of rain overwhelms the capacity of local sewers in Cook County, and when overflows fill the canals and raise water levels in the Chicago River, the MWRD must release excess water to Lake Michigan because there is nowhere else for it to go. Called a “reversal,” this means that billions of gallons of stormwater flow into the Lake, mixed with some sewage, including pollutants from runoff like hazardous household and lawncare chemicals, auto fluids, plastic bags and other debris.

Sustainable design, the core of Green Infrastructure Best Management Practices, can help to change that. But it’s not a reworking of conventional approaches and technologies. It’s a fundamental change in our collective thinking to create absorptive surfaces that will keep rain water where it falls, filter it for reuse and slow it down so our sewer system has a chance to operate as it was intended.

Using these innovative techniques to proactively manage urban land, engineers, landscape architects, municipal leaders and homeowners can create hardworking landscapes that control water and pollution while providing places for recreation, enjoying nature and learning about our environment.

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