By Jenni Spinner
Public Works Magazine
Seattle (May 1, 2007)- Seattle has backed low-impact development for nearly a decade. Follow the trail this city has blazed. In 1999, Seattle Public Utilities went on the offensive with its natural drainage systems program, launching innovative streetscape designs that boosted the beauty of the neighborhoods while reducing the negative impact of stormwater runoff on creeks, lakes, and bays.
Since then, five projects-including complete redevelopment of a 129-acre residential area-have been put into action. Here, Seattle’s low-impact development (LID) program manager Tracy Tackett lays out the path to the city’s success.
Why is LID important?
Traditional stormwater management practices aren’t protecting our water resources to the extent we need. Traditional methods are space-intensive; as we get more developed, space is at an increasing premium. LID also is much more cost-effective. Taking a LID approach allows you to take advantage of multiple environmental benefits. You end up with additional green space to create habitats, green roofs to provide insulation, cisterns to provide another water source, and anything that involves infiltration to help recharge groundwater. In time, all of this will become more important as drinking water resources become more scarce.
What actions did the city take at the onset?
We have a lot of unimproved areas in Seattle. These areas don’t have curbs, gutters, or sidewalks; we wanted to improve these areas, but in a creek-friendly manner. The merging of those two goals is what led to our first big project, “SEA Streets,” or Street Edge Alternatives. We conducted a stormwater retrofit of a residential block, a site we picked because of flooding problems and to protect a salmon habitat in the watershed. We reduced impervious surfaces to 11% less than a traditional street, provided surface detention in swales, and added more than 100 evergreen trees and 1100 shrubs. Runoff from this block has been reduced by 98%. People really took well to it, and our LID program has been growing ever since then.
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