This project will improve the water quality of stormwater runoff from roadways before it enters downstream natural systems. Roadway runoff is currently discharged untreated to a wetland south of 127th Avenue SE and SE 172nd Street. This stormwater continues south until eventually discharging into Big Soos Creek, a stream with known water quality issues related to pH, dissolved oxygen, and ammonia levels. Using Ecology-approved biofiltration systems, this project will provide enhanced basic water quality treatment to stormwater runoff from approximately 14 acres of area containing approximately 2 acres of untreated roadway.
This project will construct new stormwater conveyance pipe and catch basins to increase conveyance capacity of the stormwater system and reduce the likelihood of flooding. In order to help mitigate risk to homeowners and prevent future intrusive maintenance work, upstream stormwater runoff will be rerouted away from existing stormwater pipe systems running through homeowner properties and into the new stormwater system.
New pervious concrete sidewalks will be constructed on one side of each street within the project area. In tandem with new curbs, gutters, and landscape strips, the pervious concrete sidewalks will improve pedestrian safety by providing a pedestrian path separated from traffic by a landscape strip. Additionally, the porous nature of the pervious concrete sidewalks increase pedestrian safety and provide runoff mitigation for the new sidewalk surfaces.