Brightwater Ocean Outfall

Ballard supported the construction of the Brightwater Ocean Outfall as part of the Brightwater Wastewater Treatment and Conveyance System. This includes tunnels, pipes, and other infrastructure that moves wastewater and treated effluent to and from the thirty-six million gallons per day Brightwater Wastewater Treatment Plant. The Brightwater Conveyance System includes thirteen miles of pipeline built in underground tunnels forty to 440 feet below the surface.

Scope of Work
Ballard crews mobilized sophisticated survey systems, a heavy work-class remotely operated underwater vehicle (ROV), a 110-foot Dive Support Vessel, and other specialized diving and life support equipment to assist the prime contractor with installing and positioning the outfalls on the seafloor of Shoreline, Washington. This work took place in water depths of up to 600 feet. This outfall structure ties to the Brightwater Conveyance System where our tunnel support division provided hyperbaric support for three years. The hyperbaric team performed 1,096 safe and successful interventions at a six bar in absolute pressure, allowing mining to continue.

Innovative Solutions
Once the Outfall was in place floating above the seafloor, water was pumped into the pipeline to begin the submersion process. The outfall took fifteen hours to fully submerge and another three hours until properly on the seafloor. During this process, Ballard and team were required to maintain the position of the outfall considering the constantly changing current. The Ballard diving team aided in the submersion process once the surface support could no longer be of service. With the final destination of the outfall roughly 600 feet below the water’s surface, the dive team was critical in the execution of its proper placement. After almost twenty hours of continuous focused work, Ballard and team successfully laid the pipeline on the seafloor with surgical-like precision.

Once the submersion process was concluded, Ballard conducted a full inspection of the pipeline on the seafloor. When all was said and done, this Outfall provided the Puget Sound community with highly treated effluent fresh water from the Brightwater Treatment facility. This state-of-the-art treatment facility would be one of the most cutting edge of its kind. After the successful placement of this deep-water outfall, the final step in its construction would be finished, and it would prove to pave the way for future state-of-the-art treatment facilities that were similar.

Client: King County
Location: Shoreline, WA


• Pipeline utility project
• Early contractor involvement
• Offshore services
• Underwater inspection
• Underwater construction
• Survey/Multibeam scan
• Data acquisition services
• Pipeline repair/replacement
• Pipeline anchoring
• Pipeline stabilization
• Environmentally sensitive
• Difficult site access
• Portable marine equipment