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.
References
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