Seattle Cascade Stormwater Projects Manage Steep Slopes 

Seattle, Washington is gaining national recognition for its application of low impact development innovations. In one of their newest projects, a "Cascade" natural drainage design prototype is being used to treat stormwater from steep residential streets. 

During the past eight years, Seattle Public Utilities’ (SPU) natural drainage systems (NDS) program has completed numerous projects—ranging in scale from the retrofit of a single residential block to the complete redevelopment of 129 acres of mixed-income housing in an urban setting. All of the NDS projects help to manage stormwater in neighborhoods while also improving the appearance and function of the street rights-of-way. 

The 110th Cascade project is a series of stair-stepped natural pools that slow stormwater flows, reduce flooding, and trap pollutants before they reach Pipers Creek. The stormwater swales are located on one side of the roadway while the sidewalk is located on the opposite side of the roadway. This design manages high volumes of stormwater from large watershed areas (5 to 50 acres). For more information about this project, see the article in the latest issue of Nonpoint Source News Notes (pg 9-11) or visit the Seattle Public Utilities' website for a virtual tour of this and other NDS projects. 

A natural drainage curb extension demonstration project is also being initiated in State College, PA, modeled after the Seattle and Portland, OR projects. For more information on stormwater BMPs, contact info@fxbrowne.com.