Reducing Harbour Pollutants:
Whangarei Waste Water Treatment Plant

After a successful 26 years managing waste water treatment for Whangarei city, the local treatment plant was in need of some maintenance and a general upgrade, to ensure high quality water discharge.

The Whangarei District Council needed to address the capacity issues of its largest wastewater treatment plant, where high inflows during heavy rain events could lead to untreated sewage flowing into adjacent wetlands.  To ensure that even in extreme events all effluent received treatment,  a high level bypass UV disinfection system was constructed.

Key features:

  • Contract required detailed project management across civil, structural, mechanical and electrical works, and a broad spectrum of skills and experience from a multi-disciplined team.
  • Significant interface with the “live” plant was necessary, including co-ordination of shutdowns and management of specialist subcontractors and suppliers, together with testing and commissioning works.
  • A contractor design was necessary for the chambers, the UV building, civil and structural works.
  • Modification to existing pipework and processes within the plant and upstream of the new disinfection unit.
  • Project management staff engaged electrical specialists to provide vital power and communication/control to the UV system main distribution board, in order to activate valves, penstocks, flow meters and ancillary equipment.

United Civil Construction successfully completed these works which have doubled the disinfection treatment capacity of the existing plant and ensures that all water flowing into the wetlands and  the Whangarei Harbour has been subject to the UV disinfection process which destroys harmful bacteria and other pathogens