Wellington Sludge Minimisation Project awarded

McConnell Dowell_HEB Joint Venture awarded the Wellington Sludge Minimisation Project, by Wellington City Council

McConnell Dowell and joint venture partner HEB are pleased to announce the imminent construction of Wellington City Council’s Wellington Sludge Minimisation Project located at Moa Point.

Over the last seven months, the joint venture team has worked through an Early Contractor Involvement (ECI) process with the design team from Beca, and cost estimators Bond CM to develop the design for the new Sludge Minimisation Facility.

“We are excited to be working on such an innovative project. The new facility will generate power from the waste treatment process, and we think this sustainable approach is the way of the future. We’re proud to be working with the Council to deliver this project and help make life better for Wellingtonians”, says Fraser Wyllie, Managing Director - New Zealand & Pacific at McConnell Dowell.

This new facility will use Thermal Hydrolysis – heating under pressure - to sterilise and reduce the volume of the sludge, making it more biodegradable. Biogas will be captured and used to power the facility, substantially reducing carbon emissions. The sustainability benefits of the chosen design include:

  • Reduced sludge volumes by up to 80%
  • Reduced carbon emissions from the treatment and processing process by 60%
  • Minimises the amount of waste going to landfill
  • Produces a low odour stabilised (inert) product
  • As mentioned above, offers the potential for sludge to be used productively, including as a soil conditioner, fertiliser, and fuel for industrial heat

The biosolids produced are significantly smaller in volume than the current methods and are safe for reuse.

The joint venture has previously delivered two of the country’s largest wastewater treatment plant upgrades (Mangere Wastewater Treatment Plant Biological Nutrient Removal Upgrade and The Pukekohe WWTP Upgrade) on time and on budget and those strong relationships, the expertise and innovations will be applied to this new challenge.

Ahead of site works commencing, 1,500 native lizards living at the site were carefully trapped and relocated to protected sites at Moa Point, and in the Miramar Peninsula, like Rangitatau Park, Tukanae Street Reserve, and Centennial Park.

Following the recent site blessing by Taranaki Whānui, construction work will now get underway with completion expected mid- 2026.

To find out more information on the Sludge Minimisation Project, click here: https://wellington.govt.nz/your-council/projects/moa-point-sludge-minimisation-facility