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Earth Day and beyond: WSU research could help rain gardens work effectively

A woman walks a dog by the rain gardens in Ballard. Credit: Rita Hibbard/InvestigateWest

Distributed by InvestigateWest

When you mention Puyallup to most Northwesterners, the city’s fall fair is the image most likely brought to mind. But this suburb of Tacoma is also home to a research center that’s on the leading edge of technology used to cleanup and curb toxic stormwater runoff.

Nationwide, cities and counties are spending billions of dollars trying to reduce the amount of polluted runoff that fouls lakes and bays, floods homes and businesses, and triggers erosion. The rainwater gushes across highways, streets, parking lots, roof tops, lawns, and farms, scooping up oil and grease, pesticides, metals, and other toxic chemicals as it goes.

This spring, Washington State University’s Puyallup Low Impact Development Research Program is launching projects that scientists hope will help slow that flow of water and treat the pollutants.

The WSU researchers are testing “green” solutions for stormwater runoff, including rain gardens and porous pavement. There’s a huge demand for more information about how to maximize the use of these natural strategies.

“Our goal is to help get this stuff on the ground as fast as possible and operating as well as it can,” said Curtis Hinman, director of WSU’s Puyallup program, of the green technologies.

Seattle, Portland, Bremerton, Lacey, and Spokane are among the numerous cities installing natural stormwater solutions, which are also known as low-impact development or LID. For the most part, they’ve performed well, reducing and cleaning up runoff.

But as was recently demonstrated in Seattle when city-built rain gardens in the Ballard neighborhood turned into muddy messes, there’s a pressing need for more data on how these systems work.

The importance of the WSU program “is huge,” said Art Castle, interim executive vice president at the Building Industry Association of Washington, an organization representing the housing industry. “This is probably the best research facility for low-impact development in the country.”

In most cases, research on low-impact development has come from small-scale test sites or actual rain gardens and pavement built in communities and business areas. In the latter, the research depends on the natural conditions — some years are rainy, some are dry — that can’t be repeated. The sites can’t easily be tweaked to test various conditions. The information gathered is greatly limited.

“We will be filling a lot of data gaps in a unique way,” Hinman said.

At the Puyallup campus, a large plot of land is pocked with rows of depressions, roughly 20 feet square at the top, 10 feet square at the bottom. The 16 rain gardens are planted with a variety of grasses and plants. A giant below-ground cistern collects rainwater runoff that pours from the campus pavement. That water is then fed to the rain gardens so that scientists can see which plants grow best, how quickly the water is absorbed, and how well the pollutants are being removed.

Next to that are 20 semi-buried tubs filled with different types of soils that are used the line rain gardens to make them more absorbent. Again, the researchers are testing which work best and how clean is the water that runs off and is not absorbed.

One of the campus parking lots is being used for research as well. There, alternating parking spots are either porous or normal pavement. Some spots will be swept regularly while others will not, in order to test whether dirt and debris on an unswept lot will eventually clog the pervious pavement.

“It may look like a crazy uncle experimenting out in the backyard,” said Nate Cormier, senior landscape architect with SvR Design Co., “But what they’ve built is “a landscape that we learn from, and physically change and experiment with.”

Cormier’s firm, a Seattle-based leader in natural drainages, helped design the WSU facility. Cormier said the field of low-impact development is largely past the need for pilot projects, but the approach is not yet standard practice. A project like this one can help make that transition to wider acceptance.

It can also prove how well LID works. Right now, when developers install porous pavement, for example, environmental rules require that they also treat the water that filters through it to remove pollutants. But preliminary research elsewhere has shown that soil organisms beneath the pavement can gobble up some of the toxic chemicals. Results from the WSU site can provide hard evidence.

“That would be a really exciting example of something they would demonstrate that would save money and hopefully increase the pace of adoption of these technologies,” Cormier said. “A client would be more willing to do (porous pavement) if they didn’t have to do a water quality treatment as well.”

Cities and counties are likewise eager to find out what the WSU scientists learn.

Tracy Tackett, program manager for Seattle Public Utility’s Green Stormwater Infrastructure program, was recently asked whether she was willing to try an untested design for city rain gardens. Her answer?

“I don’t want to do it until Curtis says it works,” said Tackett, referring to WSU’s Curtis Hinman.

The research will also be important for state and federal updates of stormwater regulations. The Washington State Department of Ecology and the U.S. Environmental Protection Agency are both crafting rules that will encourage or require the increased use of green stormwater solutions. The WSU research will help show when and where these approaches work best, making them more affordable and successful.

“It was built at the level that a scientist could write papers and change laws,” Cormier said. When it comes to stormwater research nationwide, “I don’t know of anything comparable.”

InvestigateWest is a nonprofit investigative journalism center based in Seattle. For information on how you can support independent investigative reporting for the common good, go to invw.org

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