By Lani Walker
During the course of my Master’s work, I
have the opportunity to take a class in Sustainable Landscape Practice this
semester as an Elective. I am hoping
this Elective will help me in my Thesis work, which uses the outdoors as a
classroom itself. For the second week of
class, we are studying Rain Gardens; gardens which are designed to capture and
hold rainwater which would otherwise be surface runoff water. I had never heard of a Rain Garden before
this particular lecture, and I found it to be a very interesting and innovative
solution for runoff water. The project I
decided to study in depth was a residential Rain Garden in Falls Church,
Virginia. The Rain Garden is located in
the backyard to collect water directed from the home’s gutter downspout. It appears that the homeowners built the Rain
Garden without the assistance of a contractor.
The homeowners Rain Garden serves as the model in the guide, Rain
Garden Design and Construction: A Northern Virginia Homeowner’s Guide. It is stated in the above document that many
of the techniques shown were taken from an earlier document, the Rain
Garden Manual for Homeowners: Protecting Our Water One Yard at a Time
by the Geauga Soil and Water Conservation District and the Northeast Ohio
Public Involvement Public Education Committee.
This Rain Garden in Falls Church,
Virginia was built to use the surface runoff water down a small slope in the
backyard to water the garden and redirect the water to a storm sewer. The homeowners sized the Rain Garden based on
how much storm water they wanted to treat.
The Rain Garden was shaped to be wider than it is long, with the width
perpendicular to the flow of the runoff.
The Rain Garden was created by digging into the sloped area to create a
level area for planting. Then, the
underdrain was placed several inched below the surface. The underdrain was surrounded on all sides
with a thin layer of pea gravel. The
excavated soil (or engineered soil) was used to fill the planting area. To prevent erosion, they immediately seeded
the berm and covered the area with straw while the grass took root. The soil was then ready to be used for
planting the native plants. Once the
plants were planted, the area was mulched and the Rain Garden was completed. Below is part of the case study I did on this
particular Rain Garden, but the information could be applied to most Rain
Gardens in general.
ENVIRONMENTAL
BENEFITS of the Rain Garden:
The Rain Garden will capture and hold rainwater
which would have otherwise became surface runoff. The Rain Garden is covered with mulch, which
filters out pollutants in the rain water and protects the underlying soil. Using native plants in the Rain Garden can
provide a habitat and food for native species.
AESTHETIC
BENEFITS:
The Rain Garden enhances the backyard
because it will give the area more visual appeal. Also, it is possible that the Rain Garden
will attract butterflies and hummingbirds, which make the backyard an enjoyable
place to site and view. From the
pictures, the backyard appears to have more landscaping surrounding the house,
therefore, having a Rain Garden within the backyard will unify the site.
FUNCTIONAL
BENEFITS:
Aside of the environmental purposes,
this example doesn’t seem to have any functional purpose for the homeowner
other than collecting and filtering water.
SOCIAL
BENEFITS:
This example improves the social
atmosphere because it is in the backyard, a highly visible place where people
generally have gatherings. The Rain
Garden makes the area more peaceful and enjoyable for the homeowners and
guests.
EDUCATIONAL
BENEFITS:
Since it appears that the homeowners
used a How-To guide to create the Rain Garden, the building process became a
learning experience for the homeowners and neighbors.
Additionally,
this example was used to create another guide for Northern Virginia. Therefore, this project is a model for the
public who are wishing to build a Rain Garden from the Rain Garden Design
and Construction: A Northern Virginia Homeowner’s Guide.
ECONOMICAL
BENEFITS:
It appears that the homeowners built the
project without a contractor, therefore, they saved money by doing the project
on their own. It is difficult to
determine the long term financial benefits of this particular Rain Garden,
however, using native plants need less water and fertilizer once they are
established (which save the homeowner money long term).
PSYCHOLOGICAL
BENEFITS:
I have read that psychologists
say gardening is a calming pursuit; therefore the
maintenance of a Rain Garden could improve the psychological well-being of the
homeowners. Also, the Rain Garden could
serve as a place in the backyard where people can sit near and relax.
CONSTRUCTION DETAIL: Below is a quick sketch
of how the Rain Garden preforms.
Image 1: Section through the Rain Garden. By:
Lani Walker
I
found the idea of Rain Garden very interesting and now when I am on campus, I
see many areas where this solution could be used. In the future, I might even want to build
one! The sources I used for this
information are below.
Rain
Garden Design and Construction: A Northern Virginia Homeowner’s Guide
http://www.fairfaxcounty.gov/nvswcd/raingardenbk.pdf