Seattle, Washington
Venema Natural Drainage System
The award-winning Venema Natural Drainage System captures residential and road runoff from an 80-acre basin and conveys it to a cascading, linear system of 24 bioretention cells located in the City of Seattle right-of-way. Prior to the system being installed, polluted runoff was discharged during storm events into Venema Creek at the top of an eroding 80-foot sand cliff, which feeds into the fish-bearing Pipers Creek. Working with Seattle Public Utilities, the Osborn team designed a solution to improve stream habitat by mimicking natural stream hydrology through installation of bioretention cells and underground injection control (UIC) wells.
Owner
Seattle Public Utilities
The bioretention cells provide retention and water quality treatment of the runoff. The treated runoff is collected by underdrains and routed to one of three UIC wells, where it is infiltrated approximately 80-feet-deep to a point below the impermeable glacial till and into the permeable glacial outwash. The infiltrated and cleansed runoff then gradually moves laterally through the glacial outwash, where it is cooled and supports year-round base flows for Venema Creek.
