SEA Streets
Seattle City Planning Initiative
Seattle, Washington
2001

Seattle's pilot Street Edge Alternatives Project (SEA Streets), located on 2nd Ave NW, between NW 117th and 120th streets, is designed to provide drainage that more closely mimics the natural landscape prior to development than traditional piped systems.

To accomplish this, the city reduced impervious surfaces to 11% less than a traditional street, provided surface detention in swales, and added over 100 evergreen trees and 1,100 shrubs. Their goal is to get a more constant stormwater flow over a longer period of time in order to reduce peak flow volumes and increase soil infiltration, assisting in the minimization of creek erosion and flooding. Two years of monitoring show that SEA Street has reduced the total volume of stormwater leaving the street by 98% for a 2-year storm event.

This project has the potential to benefit a wide array of organizations such as environmental groups, transportation authorities, builders, and communities, giving it a strong marketability and support throughout the city.