LET’S KEEP OUR RAINWATER HERE
WHAT FALLS IN ELGIN SHOULD STAY IN ELGIN
When rain falls, two things can happen to it. It can infiltrate the soil and become an asset to local life, or it can run off and become a liability to life downstream.
James M. Patchett & Gerould S. Wilhelm
The Ecology and Culture of Water, July 1999
Land use planners and engineers have, for the most part, designed swales, drainage ditches, culverts, and storm sewers to convey water as fast and efficiently as possible away from where it falls. More and more inpenetrable surfaces mean more more and more dirty stormwater is directed into streams and rivers, carrying with it excessive fertilizers, herbicides, and pesticides from our over treated lawns, oil and cadmium from our roads and driveways, grass clippings, leaves, and pet wastes from our yards, and roof granules from our roofs. (In the case of Elgin, the city where I live, all these contaminants go into the Fox River, from which we get our drinking water.) Rain needs to be retained where it falls; rain and stormwater should be looked upon as a resource, not as something that has to be removed from the site as quickly as possible. We went through 3 ways last week; here are 5 more:
RAINWATER PART 2
- Kentucky Blue Grass has very little capacity to absorb rainwater. This is a drain set in the lawn of a townhouse community in Dundee that directs rainwater directly into a pipe that spills into the Fox River.
That little fringe at the far left side of the poster represents Kentucky Blue Grass with roots that grow as deeply as the blades grow tall. Everything to the right of that are midwestern native plants, the roots of which grow anywhere from 2-3’ to 15 ‘. 1/3 of the roots decompose every year, adding humus to the soil and creating channels through which rain can infiltrate the soil deeply .
With a natural groundcover of prairie or savanna, 40% of rainwater will evaporate, 30% will infiltrate deeply into the ground, 30% will infiltrate shallowly, and there will be no runoff.
With a 35-50% impervious surface, 25% of rainwater will evaporate, 20% will infiltrate deeply, 20% will infiltrate shallowly, and 35% will run off.
With a 75-100% impervious surface which is where our commercial areas are, and most of our residential areas with their sleek green lawns are, as well, there is 15% evaporation, 5% deep infiltration, 5% shallow penetration and 75% runoff.
(NEMO Project Fact Sheet #3, Cooperative Extension Center, 1994.)
…or combine different size chains.
7. Install permeable paving to improve rainwater penetration. This is the entrance garden at Morton Arboretum. The planting consists of a matrix of Prairie Dropseed (Sporobolis heterolepis) planted 2’ on center, interplanted with seasonal native plants–at this point, in early July, Purple Coneflower (Echinacea purpurea) and Stiff Coreopsis (Coreopsis palmata) are in bloom.
A ribbon driveway has much less hard surface. Even better would be to replace the grass with native plants.
Stone and pebble path has spaces for rainwater to penetrate into the ground,
8. Consider a green roof to hold rainwater and reduce cooling and heating costs. Green Roof in Elmhurst, IL.
. To be continued—
- Sources are Stormwater Systems by Jim Patchett and Tom Price in Sustainable Urbanism by Douglas Farr, 2008
- The Ecology and Culture of Water by James M. Patchett & Gerould S. Wilhelm, July 1999
I have a Power Point Presentation of the above slides and more to show to groups. Contact me through my web site.