Brightwater Marine Outfall

Brightwater Marine Outfall

Akana personnel provided design and construction quality control as part of the Triton Marine Construction Corporation design-build team responsible for installation of effluent pipes for metropolitan King County, Washington.  The Brightwater Marine Outfall, which is part of a $1.7 billion wastewater treatment system for advanced secondary treatment, is unique for being the largest diameter polyethylene (HDPE) pressure pipe in North America, the deepest municipal outfall, and for the extreme loading requirements during deployment and during the Design Seismic Event.

The outfall includes twin 63-inch diameter polyethylene (HDPE) pipes extending about 1 mile from the Point Wells Portal site and terminating in over 600 feet of water in Puget Sound.  At their terminus are 60 diffuser ports through which treated effluent will be released.  The twin pipes join to a wye onshore, then traverse through the soft muds of Puget Sound before emerging at 80 feet below water level. From the “daylight” into the sound, the pipes rest on the floor of Puget Sound

Akana engineers prepared QC plans for all phases of this design/build project, monitoring the various teams conducting work both on site and at off-site fabrication plants, overseeing testing of the many parts of the system, and representing the team at quality meetings with the owner.  Construction activities were monitored at three sites, including an off-site casting yard for the concrete anchors that weigh the pipe down, a pipe assembly yard where the HDPE piping was fused together, and the actual jobsite where the pipe will be connected to the newly installed Brightwater conveyance system.  The accepted price of $27.5M was 1/3 less than King County’s budget and the construction of the project was completed more than a year ahead of the County’s schedule.


Project Details

Triton Marine Construction Corporation
King County, WA

Services Rendered

  • Design and Construction Quality Assurance
  • QC Plans
  • Construction Inspection
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