30th Avenue Natural Drainage System
The 30th Avenue Natural Drainage System project is located in the Thornton Creek drainage basin. The existing roadway included driveways that were too wide and poorly defined resident parking along the edges of the arterial made adjacent travel lanes unsafe and blocked pedestrian routes. Osborn Consulting designed a roadside LID bioretention system that stormwater quality treatment of road runoff before it flows in the water quality sensitive 303(d) listed Thornton Creek. This work included bioretention modeling, conveyance design, stormwater reports, PS&E for stormwater, urban design, and landscape architecture, and provided construction support. Due to the profile of the road weir walls were required for the bioretention cells to maximize the footprint of the treatment area, Osborn developed a cheaper and simpler self-standing weir wall that reduced installation time.
Seattle Public Utilities