Dave Sandersfeld

Dayville, United States

Dave Sandersfeld start his career in 1970 as a US Forest Service “Wilderness Ranger” in the Frank Church/River of No Return...

Rain Gardens Concept

“Rain gardens” trap water pollution

Nov 29, 2007
LDB Solutions

By Robert Scheyer
Editor’s note: This article is an excerpt from an article that will appear in the January/February edition of Livescapes magazine.
Rain Gardens are curbside perennial plantings that trap what The Environmental Protection Agency calls “non-point source” water pollution. Non-point water pollution is runoff from impermeable surfaces such as roofs, driveways and lawns that collect dirt, fertilizers, chemicals, oil and bacteria. It is called non-point because the EPA cannot point to a specific culprit, like an oil spill. Rather, it is simply what accumulates in the normal course of property ownership among responsible people.
Landscapers can offer rain gardens as an environmentally friendly option to their clients. In some cases, municipalities are hiring landscape contractors to install large numbers of rain gardens.

Rain gardens are designed to collect and filter runoff from a slope.
A Rain Garden must catch and hold water runoff before it gets into a storm drain. So, wherever storm water runoff collects or flows is a prospective site. Likely sites include the bottom of a hill or ravine; or on a slope through which water flows. For instance, an effective placement is near the end of a roof’s gutter system where water drains out.
Design Tips
Other important considerations are size and shape. A Rain Garden should be about 20% the size of the roof, patio, or pavement area draining into it. In most cases, this will be between 100 and 300 sq. ft. The shape should be both ascetically pleasing and appropriate to catch water runoff. However, even a small garden, when properly placed, has an impact.
Once the proper location, size, and shape are determined, a concave depression or “swale” is dug. This is different from a typical perennial garden. A concave depression is necessary to collect the runoff. Some of the soil excavated from the site is used to form a soil “lip.” This is built up on the downside sloping edge of the depression, next to the place to be planted. The resulting dig should leave a 6- to 12-inch, bowl shaped, depression in the ground.
This often means that some dirt will need to be excavated and hauled away. Soil amendments, such as sand, compost, and peat moss, are tilled into the bottom. Plants are dug in and the area is mulched.
For more information on rain gardens, be sure to read the January/February issue of Livescapes and visit:
• 10,000 Rain Gardens
• Rain Gardens of West Michigan
• Virginia Department of Forestry
• Wisconsin Department of Natural Resources
• Rain Garden Network
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Scheyer is manager of GardenScapes, a landscaping compaany in Lincoln, NE.

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