Stormwater Detention and Treatment


A large component of site development is the control of peak flows and the protection of water quality for storm runoff leaving any developed site.  Throughout the evolution of stormwater codes, regulations, and design criteria in the Pacific Northwest, TEC has been a leader in the field for our expertise and understanding of local drainage issues, agency requirements, and for implementation of cost-effective and practical solutions to diverse drainage situations.  TEC designs large scale flow control storage facilities such as surface ponds, vaults, and tanks where needed and appropriate.  We also design more natural Best Management Practices (BMPs), such as infiltration, dispersion, and raingarden facilities where they are better suited for the site application.


TEC designed this mixed-use regional detention facility on the Northwest University Campus in Kirkland, Washington.  Located within the historic "college green", the facility was designed with large flat areas for playfields and usable lawn and green space.  It was also shaped as an amphitheater to facilitate use for outdoor concerts and other performances.  The facility was analyzed using King County's KCRTS computer modeling, and was sized to mitigate downstream erosion problems. 




TEC designed and prepared permit and construction documents for improvements and removal of contaminated sediment from the Brookhaven, Forbes Creek, and Hourglass ponds in the City of Kirkland.  The project included access, bypass piping, sensitive areas restrictions, difficult removal and transport of wet sediments, partial culvert replacement, and complete restoration and enhancement of disturbed areas.

At the 520-unit Heights at Burien apartment complex, TEC  provided design and construction administration services for the installation of this arch chamber detention and infiltration facility.  Treatment of storm runoff is by cartridge filters for this "retrofit/infill" project on the already densly developed site.