In the Fremont neighborhood of Seattle, a multi-phase stormwater cleanup effort is setting a new precedent for how cities and communities around the world can tackle challenging toxic stormwater runoff problems.

As part of the Data 1 Office project, the design team learned of the lethal
effects the runoff was shown to have on the region’s salmon, five species of
which swim below the bridge during annual spawning runs. Research from a UW
researcher showed that green stormwater infrastructure could neutralize the
lethal effects of the pollution, and a larger effort was born to take action
to improve our local waterway.

In collaboration with the DATA 1 and Watershed client, CoU, LLC, the green
rating system Salmon-Safe, and KPFF’s civil engineering team, Weber Thompson
has helped spearhead this multi-phased effort to improve the health of Lake
Union. The Aurora Bridge, Washington State’s historic 1932 structure which
funnels Highway 99 traffic north and south, has been found to have runoff six
times more toxic than the national standard. This bridge runs directly
adjacent to both DATA 1 and Watershed, and the client decided to tackle the
challenge head-on.

Innovative stormwater retention cells have been installed in the right of
way at both DATA 1 and Watershed, extending the landscape for the buildings
and creating lush green spaces where dark, damp under-bridge sidewalks
previously dominated. The planters are filled with vegetation that naturally
scrubs stormwater, allowing dissolved pollutants to settle before the water -
much cleaner than before - is diverted back into Lake Union.

The first two phases of this work were financed by the DATA 1 and Watershed
client. Now, a third phase has been completed across North 34th Street thanks
to a non-profit, Clean Lake Union, which was created to advocate for
continued clean up efforts around the lake. Additional funding and advocacy
has come from The Nature Conservancy and the Boeing Company. Together, these
three phases treat up to two million gallons of water annually from the
entire north span of the Aurora Bridge.

The Aurora Bridge Swales Project is an exciting new model. The work has
inspired additional investigation to size and locate infrastructure for the
south span of the Aurora Bridge, as well as the five other bridges that cross
Lake Union. All totaled, this project seeks to mitigate over 98 million
gallons of polluted runoff entering Lake Union.