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Credit: Photo: Rusty Schmidt, URS Corp.

A rain garden at a residential property in Burnsville, Minn., was installed to treat storm-water runoff from the street.
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Credit: Photo: Rusty Schmidt, URS Corp.

This rain garden in Plymouth, Minn., accepts stormwater runoff from the adjoining roadway.

Rain gardens can be employed in urban or suburban settings, as illustrated by a recent effort conducted by the city of Portland, Ore. Known as the Southwest 12th Avenue Green Street Project, this urban rain garden takes full advantage of the sidewalk area adjacent to a downtown street while also accounting for the needs of pedestrians. The innovative project consists of four planters, each with a landscape area of 4x17 feet. Curb cuts enable runoff to enter the planters. There, common rush (Juncus patens) filters the water, while its roots and the roots of a Tupelo tree (Nyssa sylvatica) aid infiltration. A3-foot offset of concrete pavers on the street side of each planter and pathways between the planters facilitate access to vehicles parked next to the rain garden.

Designed to cleanse and infiltrate street runoff from an area of about 8000 square feet, the rain garden is expected to capture an estimated 180,000 gallons a year, said Kevin Perry, a project designer with Nevue Ngan Associates, a Portland-based landscape architecture firm. In his previous position as project designer for Portland's Bureau of Environmental Services, Perry designed the $30,000 project. Arecent flow test determined that the planters achieved infiltration rates of 2¾ to 5½ inches per hour, results Perry terms as “very positive.”

Perry recommends that other cities consider adopting similar approaches. “These projects are quite nice because they provide direct environmental benefits and they often provide ancillary benefits for pedestrians,” he said. “They ‘green' the neighborhood.”

EDUCATING THE PUBLIC

The city of Chicago has installed several dozen rain gardens on public property in the past five years, said Sadhu Johnston, commissioner of Chicago's Department of Environment. To encourage residents to build their own rain gardens, the city distributes plants annually for use in such efforts.

A major challenge in motivating the public to create rain gardens, according to Johnston, is simply increasing awareness of their existence; he said citizens often do not realize that they can take steps in their own yards to improve water quality.

To educate the public about rain gardens and motivate individuals to add them to their yards, local governments in the Kansas City, Mo., metropolitan area launched the 10,000 Rain Gardens initiative last year. Developed as part of an overall approach to reducing stormwater runoff and improving water quality, the effort aims to spur the public to construct that number of rain gardens within the next few years. A Web site (www.rainkc.com) devoted to the project was created to inform the public.

Although the 10,000 Rain Gardens initiative by itself is not expected to eliminate sewer overflows, it should help by reducing peak flows, said Scott Cahail, environmental manager with the Kansas City Water Services Department. Faced with the rising costs of addressing overflows and improving the health of its various watersheds, the city recognized that rain gardens can help with stormwater management in ways that pipes and concrete cannot. Ultimately, said Cahail, the city and its regional partners realized that at times, “green may have benefits over gray.”

— Landers is a freelance writer and editor based in Austin, Texas.