Going Green By Thinking Blue
- By Jack Womack
- April 1st, 2009
Imagine a place where rainwater and ecology are part of a child’s curriculum, where the amenities around the school are developed upon a framework of design principles that reintegrate students into the environment — a place that cherishes the environment as an asset, and where open space is based upon a system of living, native landscapes. When rain falls from the sky, it is treated as a resource, not a waste product. State-of-the-art storm water management systems integrate rainwater into the landscape and building, cleansing and infiltrating the water as it did in a historical-based hydrology.
Imagine schools where teachers and students grab their umbrellas and run outside to watch the first rivulet of rainwater begin its journey off the roof, across a terrace, and into the rain garden where a series of plants absorb and clean the rain. Imagine a school where kids use the outdoors as a living laboratory; where green herons, red-tailed hawks, and saddle-bag dragonflies are a common occurrence. Imagine you’re surrounded by the sounds of nature so deafening that you forget you are at school!
On every project, we try to indoctrinate this type of thinking to make the imagination a reality. In fact, it’s not as complicated as it might sound. The process begins with two design precepts that are paramount to making this dream come true — make the site more permeable, and reinvest in our native landscapes.
Make the Site More Permeable
The Midwest region receives approximately 37.5 in. of precipitation per-acre per-year, or about one million gallons of water per acre per year. If you equate that to a school site that is even a modest 25 acres, you are looking at 25 million gallons of precipitation that fall on the property. With the advent of conventional development practices (large tracts of impermeable surfaces), most, if not all of that water ends up somewhere other than back in the ground where it can no longer recharge local aquifers or re-enter the ecological circle for plants and animals. As designers, we have forgotten rainwater’s inextricably complex yet conceptually simple link to everything — rain falls from the sky as a natural resource for use by everyone.
To break the cycle of conventional land development and acres of impermeable surfaces, a few simple tools can be used to make our sites more permeable, including;
- rain gardens,
- permeable pavers, and
- green roofs.
A rain garden and bioswale are functionally the same technique; they are depressed areas that take runoff from an adjacent impermeable surface and infiltrate it through soils that have been augmented to make them more permeable. This is especially important when the adjacent surface is a parking lot. Between rain events, a parking lot will collect oil, detergents, particulate matter, and a number of pollutants. When a bioswale or rain garden is used, the “first flush” of polluted water sheeting off the lot is intercepted and cleansed through natural processes inherent in soil and certain plants. Runoff that passes through a rain garden or bioswale is quite often cleaner and better for the environment than if it ran through a conventional storm water management structure.
Permeable pavers are another strategy to infiltrate rainwater. Imagine every drop of rain that falls on a parking lot disappearing immediately through the surface; this is exactly how permeable pavers work. They are interlocking concrete pavers that include a small notch in the corner of each. This notch, or hole, is backfilled with granular material that allows water to infiltrate through to the rock below. Once below the surface of the paver, water migrates in numerous directions either infiltrating or evaporating back through the top. In the rock, naturally occurring microbes have the ability to break down, over time, many of the pollutants listed above.
This construction technique not only infiltrates water but also reduces urban heat island effect — the phenomenon of heat reflecting off of dark surfaces and back into the atmosphere. Permeable pavers, because of their lighter color, reduce this effect to a tolerable level and actually make the parking lot pleasantly cooler.
Green roofs are another strategy to make a site more permeable. Like a parking lot, a roof will shed nearly 100 percent of the rain that falls on it. A green roof can easily offset that amount by upwards of 75 percent. In other words, a green roof can hold almost 75 percent of the water that falls on it. Green roofs come in many shapes and sizes but the common denominator for all of them is that they are made of lightweight soils, over a waterproof membrane, with some ability to hold water, and include plants acclimated to the proper growing condition.
If designed properly, a green roof could easily become an extension of any school curriculum. Imagine if students could walk out of their classroom and onto the roof to study plants, water, weather, and more. What is typically seen as wasted space now becomes a living laboratory.
Reinvest in Our Native Landscapes
Ahhh, the lawn mower, keeping our lawns uniformly manicured. The lawn, however, has depleted our soils of important molecular structure and microbiota needed in nutrient cycling. Studies have shown that many of our fruits and vegetables grown directly in the ground have 20 percent to 30 percent less nutritional value than those grown just 30 years ago. Why? Because we have taken the soils support system and sent it “somewhere else.”
That “somewhere else” is the Gulf of Mexico where approximately 8,000 sq. mi. of dead zone exists. The dead zone is due in large part to urban runoff, which is any runoff that comes off of our streets, buildings, and landscapes. As rainwater moves across the contemporary landscape, it picks up and moves large quantities of phosphorous, nitrogen, and heavy metals into our local streams and rivers, eventually finding its way downstream into the Gulf.
Reinvestment in our native landscapes can help solve this problem while providing invaluable learning tools for students. A native landscape is a self-replicating system that puts nutrients back into the soil by decomposing its roots a little bit every year. Our native landscapes — in particular prairie plants — sequesters carbon, provides wildlife habitat, absorbs rain water, eliminates soil erosion, reduces maintenance costs, supports an infinitesimal amount of micro-organisms (it is estimated that there are over 100,000 organisms in a tablespoon of prairie soil), and does not contribute to the Gulf of Mexico Dead Zone.
Picture just a few areas of your own school grounds dedicated to native landscapes that can be incorporated into your schools curriculum. For schools in residential areas, these respites of nature could provide neighbors a place to enjoy the seasonal beauty a native landscape affords, as well as the butterflies, dragonflies, hummingbirds, and more.
A more serious and health-correcting benefit derived by prairie is the reduction in airborne pollen that triggers hay fever and asthma. How? Every single plant in a prairie is pollinated by an insect. Prairie plant’s pollen is too heavy to be airborne and must be moved by an insect, which is a big reason that prairies are teeming with life. On the other hand, turf grass lawn’s pollen is made to be airborne and thus has created a multi-billion dollar hay fever and asthma epidemic.
Getting started is up to you, and it can simply begin by recognizing the surfaces around your school and knowing where rainwater runoff is going. You have taken the first step toward making your property more permeable through this recognition and by asking, “how can we absorb or reduce runoff?” Then, you can ask the question, “Will a rain garden or bioswale be the appropriate strategy?” For the school itself, it may be as easy as implementing a rain garden at every downspout that touches the ground. For the parking lot, it may be a bit more difficult, but if you have sheet flow leaving the lot into turf areas, you may be able to implement a bioswale.
Permeable pavers are a much larger capital investment and can be very costly if retrofitting an existing lot. New construction can help alleviate this but there is still the issue of upfront cost. A great success story for the permeable pavers’ upfront cost comes from the Morton Arboretum in Lisle, Ill. In 2002, the arboretum reconstructed a 500 car parking lot. Looking at a 50-year life cycle cost analysis they found that an all asphalt parking lot would cost $1.3M if maintained properly, while the same lot made with permeable pavers would cost no more than $25,000 to maintain. Although the upfront cost was more, the long-term savings will be considerable. Green roofs fall under the same capital investment category as permeable pavers — very expensive to install but can offer significant returns on the investment.
These tools for sustainable design can be a tremendous resource for the enhancement of student curriculum and treats rain as a resource, not a waste product. Anything we can do, either as an individual or group, will make a difference and will teach students that the choices made at their school are having an impact on the environment — a positive impact.
Jay Womack, ASLA, LEED-AP is director of Sustainable Design for Wight & Company, a nationally recognized A/E firm based in Darien, Ill. Jay’s professional background reflects his lifelong affinity for the Midwest’s natural areas, which has influenced his design philosophy to partner art, science, and ecology.