Rain Gardens Bring Flair to Storm Water Management

By Amy Rose Davis

Rain gardens are beginning to flow as wise sustainable moves that are also pleasing aesthetically.

The 10th Street Rain Garden uses a variety of grasses to help water absorption.

“The early engineering approach to [rain gardens] was to put a big hole in behind the building,” says Carol Mayer- Reed, partner-in-charge of landscape architecture at Mayer/Reed, a Portland design firm. “Portland is trending toward using them as features in front of projects.” Mayer-Reed has worked on rain gardens for many years, including the award winning rain garden at the Oregon Convention Center. “Who doesn’t love a waterfall?” she adds.

The term “rain garden” is used to describe a variety of stormwater treatment designs. At the most basic, a rain garden is a bioswale or what Mayer-Reed calls a “farmer’s ditch” – a shallow area that collects stormwater runoff from parking lots and pavement and allows it to filter back into the aquifer. The natural filtering process reduces pollutants.

But Mayer-Reed and others are now bringing rain gardens out of the shadows and combining their functionality with beauty and education.

“When dealing with LEED or sustainable components, if we can make them visible, then we can use them as educational tools,” says Kurt Lango, principal at Lango Hansen Landscape Architects in Portland.

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Lango has worked on a variety of stormwater treatment projects that incorporate rain gardens, swales or water features. Rain gardens and water features associated with them allow landscape architects and building owners to recapture water quality without “pumps or equipment – just gravity,” Lango adds. “We get to do something dynamic and interesting in a garden.”

Rain gardens are becoming commonplace around Portland and surrounding areas and are giving neighborhoods an aesthetic facelift.

Lango Hansen designed the 10th Street Green Street project in Lake Oswego, Ore., a project that involves a half mile of stormwater gardens along a residential street.

The gardens are designed to beautify the neighborhood while draining stormwater.

The city of Portland’s Bureau of Environmental Services has an entire program devoted to green streets. On SW 12th Avenue near Portland State University, the city retrofitted the street to collect runoff from 8,000 sq ft into a series of four planters. Each planter collects water to a depth of 6 in., then water overflows down the street to the next planter. The project won a General Design Award of Honor from the American Society of Landscape Architects in 2006.

Thornton Creek, a mixed use development in North Seattle, does more than provide a rain garden. Owner Lorig Associates, Seattle, combined the need for stormwater management with the public’s desire to daylight a creek that had been covered during construction of a nearby shopping mall. The creek now runs through the public part of the project.

While it’s harder to retrofit a building to include a rain garden or other water-quality treatment options than it is to design those features into new construction, it is possible.

Mayer-Reed says her firm has designed and installed rain gardens and stormwater quality features everywhere from the Washington State University Salmon Creek Campus to tight urban areas such as the AIA Portland Chapter office in northwest Portland. Rain gardens are a way to “adapt nature’s process to an urban environment,” she says.

Lango says Portland’s Bureau of Environmental Services “has a ton of plant lists” to help designers find plants that look good throughout the year. Mayer- Reed says that in the Portland area, several schools now have rain gardens that were planted by parents or neighborhoods, some in conjunction with the city. These projects represent “a much more holistic approach” to creating sustainable communities, she says. “Water is a system that connects people. It doesn’t stop at property lines.”