Berger Partnership designs a green infrastructure facility that’s part of the neighborhood.
By Katharine Logan
As climate change and urban growth stress the ability of combined storm and sewer systems to handle the volume of water besieging cities, infrastructure that would once have been relegated to industrial outskirts increasingly needs to fit within mixed-use neighborhoods. In south Seattle, the Georgetown Wet Weather Treatment Station is meant to model replicable solutions while becoming “an integrated part of the community: accepted, acknowledged, actually liked,” says Michael Popiwny, the architectural design and mitigation manager for the King County Department of Natural Resources and Parks, who served as the senior project manager during the design phase of the facility.
The $275 million treatment plant, which will come online only during storms, is designed to prevent up to 70 million gallons a day of combined sewer overflow (CSO) from streaming into the Duwamish River. Acting as a sort of mechanical surrogate for the river’s long-lost mudflats and the ecological filtration they would have performed, the Georgetown Station will receive and clean contaminated runoff diverted from two Duwamish outfalls. In addition to engineering-based CSO treatment, the station will use green infrastructure to manage all of the rainwater that falls on its own, densely developed lot. Through strategic design of the plant’s massing and configuration, the station achieves this on just under three acres, about a third of the footprint that such a facility would typically need.
“As landscape architects, we played a relatively small part compared to the massive engineering effort,” says Jonathan Morley, ASLA, a principal at Seattle-based Berger Partnership, the landscape architects for the project. “However, it’s an important part because it’s going to be the most visible.” Berger analyzed a dozen or so sites to inform the county’s selection, shaped the project’s design guidelines in consultation with community representatives (whose priorities included educational engagement and neighborhood improvement for the industrial-turned-hip area), collaborated in an integrated design process to configure the project on-site, and designed the working landscape components that form the station’s urban edge. These elements both contribute to its public appeal and demonstrate what green infrastructure can do.
Rainwater management strategies on display include bioswales, complete with seating areas to accommodate visiting school groups; rooftop collection, where cisterns and downspouts are held above grade to make the water flow visible; permeable paving; and reinforced planting, using Leptinella squalida and Acaena microphylla, turf substitutes that can withstand light vehicular traffic. Berger’s design for the perimeter fencing, inspired by the reed-weaving technology of the Duwamish Tribe, elevates expanded metal mesh fabric, a basic industrial material commonly found in the neighborhood, with plays of light and transparency. “The facility is not trying to hide,” Morley says. “It’s trying to engage the community and to welcome that engagement.”
Projects like the Georgetown Wet Weather Treatment Station exemplify the difference good design can make. “There’s a lot of money in public infrastructure, so there’s the chance to create great examples of landscapes that treat stormwater and help integrate required facilities into the community,” Popiwny says. “You want that to get out—to be understood and available to utility professionals around the country.”