NE 40th Water Quality Facility Redmond, Washington

Enhanced treatment of highly-polluted highway stormwater runoff is accomplished across 19 acres with the unique design of this water treatment facility. In developing the city of Redmond’s Basin Surface Water Master Plan, the facility addresses water quality for what flows into its stormwater trunk extension using a custom pump and distribution system.

A Unique Water Treatment Facility Utilizing Bioretention for Highly-Polluted Stormwater Runoff

Located alongside the busy highway, SR 520, a unique pump system diverts stormwater runoff through a custom soil mix and vegetated facility designed for biofiltration before eventually reaching the outfall at Lake Sammamish. The resulting bioretention maintains treatment function over time as a custom steel distribution system spreads flow evenly to optimize the footprint across the facility and prevent scouring. Data collected to inform the Basin Surface Water Master Plan was used to identify the optimal location for capturing polluted runoff while continued monitoring refines the runoff model and better defines pollutants. An integrated approach including landscape architecture focused on urban design led to a facility that resembles a leaf. Otak also supported the city in obtaining an ecology grant for the stormwater retrofit by building a report that demonstrates how the facility would function and how the water quality benefits would benefit the community.