Award-winning outfall

Opus was the Principal Design Consultant in the design-build team responsible for the Brightwater Outfall in Seattle, Washington.

The outfall consisted of twin 1.6 metre diameter HDPE pipes extending about 1500 metres into Puget Sound. The value of the project was US $27.5 million, and it was competed below budget and ahead of schedule.

The outfall is the largest diameter HDPE pipe in North America and the deepest municipal outfall in North America, discharging at a depth of approximately 200 metres. The design had to overcome many challenges including steep offshore slopes sensitive to liquefaction, extreme loading during a seismic event, critical hydraulic design requirements for headloss and effluent dispersion and construction in a sensitive marine area.

The project has received more than 10 awards, including the Association of Consulting Engineers 2009 Engineering Award of Excellence in the Municipal Category, the American Public Works Association (Washington State Chapter) 2009 Environmental Project of the Year and the Consulting Engineers of British Columbia Municipal Award of Excellence 2009.