As students progress through the undergraduate program at Southern Illinois University-Carbondale, the curriculum challenges us in myriad different ways. We learn about various topics on building composition, site design, and aesthetics. Unfortunately, during our stay, we may miss some information in class due to funny cat photos or challenging internet games. If we fall victim to these ever-important pitfalls, we may later find ourselves lacking knowledge on various topics.
For myself, I recently came to grips with my lack in landscaping design prowess. In the effort to become a more well-rounded architecture student, I took the opportunity to enroll in an environmental landscaping practices class this spring. Though the semester is hardly out of the gate, my classmates and I are already learning about some interesting landscaping elements including rain gardens and permeable pavements.
Rain gardens, the first element we learned of, are depressions or holes within a small drainage basin or swale that is home to various shrubs and trees. Its purpose is to reduce rainwater runoff from impervious ground cover or roof drains. Along with other aspects, it also helps to roughly filter the water of certain pollutants before it reaches the localized water system. According to a paper by Sandy Coyman and Keota Silaphone, a well designed rain garden can reduce localized pollution in creeks and streams by 30% (Coyman, Silaphone).
As shown in the illustration, rain gardens may be used for the purpose of rainwater mitigation from a rain spout in some residential applications. The soil substrate for the growth of the plants in the garden are often placed above a drainage layer of various thicknesses. Also, a perforated drainage pipe can be used in gardens with an excess water intake.
Along with rain gardens, we also learned about the correct installation of certain types of permeable pavements. As with rain gardens, permeable pavement greatly reduces excessive runoff and flooding in the built environment. The concept of the system is to allow some rainwater a route to the local water system through the surface of the pavement itself instead of through a large municipal drainage system. It does not commonly have the filtering capabilities of a rain garden with the omission of a large body of plants.
The adjacent illustration shows the relation of the surface paving system in relation to the drainage system below it. Just as with the rain garden, there is a sequential increase in the size of aggregate toward the bottom of the drainage system to allow for greater flow of water. A perforated drainage pipe helps to control excessive levels of water behind the curb to keep it from shifting. With the inherent qualities in the permeable paving system, it is often used for driveways or other applications where a curb would not be uncommon to find.
Sandy Coyman; Keota Silaphone. "Rain Gardens in Maryland's Coastal Plain". p. 2. Retrieved 11 October 2011.
(2013, July 18). Residential Rain Garden [Web Drawing]. Retrieved from http://vienna- wv.com/portal/2013/07/18/what-is-a-a-rain-garden/
(2011, May 23). Permeable Paving Units-Typical Installation [Web Graphic]. Retrieved from http://www.jpwaredesign.com/2011/05/