These days, adhering to sustainability practices is expected of businesses and public agencies. And in vigilant cities like Portland, sustainability practices even reach beyond the norm, achieving greater than average awareness.
But a new stormwater green wall installed at Portland’s Expo Center is unique by this city’s already high standards. Located at the Expo Center’s Hall E, the 30-foot tall and 60-foot long green wall is a special addition to the Expo Center campus and the local sustainability world because it manages stormwater runoff. Green walls are traditionally built for their ability to cool down warm climates and provide a sense of nature in urban environments. Rare is it to find one that also treats stormwater runoff – at least locally.
“The key difference between a standard green wall and the Expo's stormwater green wall is that our green wall treats stormwater before hitting the final drains, reducing the amount of runoff reaching our waterways,” says Matthew Rotchford, the Expo Center’s director.
“There’s only one other green wall that I know of that manages stormwater,” says Amy Chomowicz, Ecoroof Program Administrator at City of Portland’s Bureau of Environmental Services, which oversaw the Expo Center project. “And that one’s in London.”
Rotchford credits Chomowicz and an entire team of public and private agencies for making the stormwater green wall happen, including Portland’s Bureau of Environmental Services, Metro, which manages the Expo Center, and the Environmental Protection Agency, which largely funded the project. Portland-based GreenWorks P.C. Landscape Architecture, Cascade Design and Colton Construction designed, engineered and constructed the green wall.
The large number of public and private agencies could have made for a complicated partnership but the collaboration worked seamlessly, largely because each agency shares the same vision for environmental advocacy.
“This project fits well with our emphasis on expanding Portland’s green infrastructure to manage stormwater,” says Dean Marriott, director of Portland’s Bureau of Environmental Services. “This is a good example of the kind of work that has helped make Portland a national leader in innovative stormwater management and we are very happy to work with Metro on this exciting project.”
The Bureau of Environmental Services is the city’s sewer bureau. Besides overseeing the Expo Center, Metro’s mission includes an enduring commitment to steward natural green spaces around the region as well as applying the highest sustainability principles across all of its venues and programs.
From conception to final construction, the stormwater green wall took nearly two years to complete. BES had secured a large grant from the EPA to fund innovative projects and was looking for potential sites, Chomowicz says.
Meantime, Rotchford says the Expo Center was looking for opportunities to beautify its campus while also reducing the amount of stormwater runoff produced by the 53 acre campus’ five major exhibit halls totaling more than 333,000 square feet.
“For a location like the Expo Center, you can imagine that our impervious square footage number is a large one and something we are working hard on mitigating,” Rotchford says.
As it happened, both agencies had been looking for opportunities to work together, too. Still, Chomowicz says the Expo Center site had advantages that made it appealing no matter what.
The Expo Center stormwater green wall isn’t a traditional bioswale or garden that inhabits a lot of expansive space. Instead, it’s a site that requires use of a lot of vertical square footage.
“The geometry of its roof and wall made it very easy for us to get the flow from roof to wall,” says Chomowicz. “We looked at other places, other locations. But this one was simple.”
While Chomowicz and BES oversaw the project, Lydia Neill, Metro’s construction supervisor, and Molly Chidsey, Metro’s sustainability coordinator, added technical assistance.
Standing 30-feet tall and 60-feet long, the free-standing structure is made of steel and aluminum and is adorned with soil and vegetation native to Oregon, particularly the Columbia River Gorge, according to Mike Faha of GreenWorks, which took the design lead on the project.
What’s more, no pumps are used to flow the water through its travel channels.
“Ours is a simple and elegant approach,” says Chomowicz. “The water flows by gravity from the roof through different channels.”
BES and other public agencies will monitor the green wall to find out how much stormwater it holds. Metro’s Neill says there will also be efforts to develop signage to signal to the public the green wall is more than a pretty feature.
“There’s an educational component going on here, too,” says Neill. “We want to explain how this structure is more than architecture. It’s connected to good, sustainable practices and mitigates the Expo’s footprint.”
As the stormwater green wall is welcomed by the public, Rotchford says everyone will evaluate the project and decide if it can, and should be, duplicated by others.
“If this design works well, we all hope to see it duplicated elsewhere,” he says. “But another hope is that the science behind this innovation will be something that brings architects and designers from all over the world here to Portland. They’ll get to see what was among the first of its kind ever to be created.”