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Brightwater Outfall

 

Country: Canada
Key Area: Water
Services: Wastewater Treatment

The Brightwater Outfall is part of a CA $1.7 billion wastewater treatment system.  The design-build project was awarded to Dayton & Knight Ltd (now Opus DaytonKnight) as the principal design consultant.  The Brightwater Outfall is unique for being the largest size of high-density polyethylene pressure pipe in North America and the deepest municipal outfall. Summary

  • Discharge Depth 200m.
  • 120m of 2100mm Diameter Steel Pipe.
  • 1650m Long.
  • 1530m of Twin 1600mm Diameter High Density Polyethylene (HDPE) Pipe.
  • Extreme loading requirements during deployment and during a seismic event.
Challenges
  • Sensitive marine areas with environmental sustainability permitting requirements and tight scheduling.
  • 25% to 30% offshore slopes with soils sensitive to liquefaction and sliding.
  • Critical hydraulic design requirements for head losses, and effluent dispersion.
  • All pipes and connections required to be installed with divers or remote operating vehicles (ROV).
  • Four ballast weight designs were required to control loading.
  • All ports and access hatches are designed for high pressures and opening at 200m depth
Achievements
  • A tough, durable outfall has been provided at the required location and depth.
  • The strict environmental sustainability permit conditions and construction site disturbance conditions were met.
  • A program for hydraulic analysis of the outfall and the diffuser was developed.
  • A complex weighting system and a seismic anchor were developed to address the soil liquefaction and sliding concerns.
  • An ROV compatible opening system for the ports and hatches was developed that did not result in undue risk during the high stresses of deployment.

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