Moa Point sludge minimisation facility

About the project

Sludge is the name for the solids created through the wastewater treatment process. It is not an easy, or nice, material to dispose of. At the moment it’s piped 9km across Wellington to the Southern Landfill, where some of its water content is taken out. What’s left is buried in the landfill – our current consent means we have to mix one part sludge with four parts general waste.

We’re building a facility that will change all that. The sludge minimisation facility will reduce the volume of sludge created by up to 80 percent by creating a stable, dry, odourless product that can be more easily transported, and used in productive ways such as a soil conditioner and fuel for industrial heat.

The facility will make it easier for us to meet our goals in our Te Atakura: First to Zero and He anamata pare kore mō Pōneke: A zero waste future for Wellington.

But that’s not all:

• The facility will reduce emissions created through the treatment and processing of sludge by up to 60 percent.
• The sludge will help power all this treatment – as it breaks down it will produce a biogas that is captured and used to create heat and electricity to help run the process.
• What we’re building aligns with mana whenua values, such as the principles of rahui in disposing of human waste, harnessing the resources in sewage sludge to give them another life, and kaitiakitanga – having a positive impact on the environment and our communities through the action we take.
• The facility uses a process that includes hydrolysis, anaerobic digestion, dewatering and thermal drying.

How the process works

The heart of the new Moa Point sludge minimisation facility is the anaerobic digestion process, which mimics the natural decomposition process of waste, breaking down biodegradable matter in the sludge. As the sludge breaks down, it produces biogas which is captured and used to produce heat and electricity, which helps run the process.

To make the anaerobic digestion process even more efficient and harness more energy from the sludge as it breaks down, the sludge is first put through thermal hydrolysis. This acts like a pressure cooker on the sludge, breaking down the sludge molecules so that the sludge becomes easier to digest in the anaerobic digesters. It also makes the sludge easier to dry.

Because the product is inert, it can be easily stored or transported to other locations for disposal or potentially used productively for other purposes.

Benefits for Wellington

This new facility will have positive impacts for our city:

• Environmental impact: Significantly reduces waste and carbon emissions, contributing to a greener, healthier city.
• Long-term cost savings: Efficient waste processing will potentially reduce future waste management costs.
• Community health: Cleaner waterways and a reduced carbon footprint contribute to better public health.
• Compliance: Helps the Council meet local and national waste minimisation standards.

New levy for ratepayers 

In August 2024, we will introduce a levy to all ratepayers.

The purpose of this levy is to cover the approximately $400 million required for this new facility without affecting the funding for other important infrastructure and community projects.

Approved under the Infrastructure Funding and Finance Act 2020 (IFFA), we consulted on this option through 2021/2022 and received support from the New Zealand Government (Cabinet and the Minister of Housing) in August 2023.

We are collecting the levy on behalf of the special purpose vehicle owned by Crown Infrastructure Partners.

For more information about the project funding, see:

Sludge Minimisation Facility Project Funding (312KB PDF)
Ministry of Housing and Urban Development
Crown Infrastructure Partners

Who will pay the levy

All residential and commercial ratepayers will pay the levy.

Properties connected to the Moa Point and Karori wastewater treatment plants will pay a higher levy because of the direct benefits they'll receive. Most properties in Wellington City will be connected.

Those not connected to these facilities will still get the benefits this facility will bring to the city so will pay a smaller levy. 

Protected Māori land is excluded from this levy.

Cost of the levy

The next rating year (2024/2025) the total levy will be approximately $8 million spread across all eligible ratepayers.

The cost for individual ratepayers will differ depending on:

• whether a property is commercial or residential,
• what its rateable value is, and
• whether it is directly connected to Moa Point or Kaori wastewater treatment plants. Most properties in Wellington city will be connected.

Because of those various factors, we cannot tell ratepayers what their levy will be ahead of time, but we can give an estimate for some example properties, as below. 

Please note these are indicative only: 

• Residential, connected with a capital value (CV) of $1 million:
  The levy will begin at about $81 in 2024/25 and increase to about $326 per year by 2027/28.  
• Commercial, connected with a CV of $1 million:
  The levy will begin at about $121 in 2024/25 and increase to about $483 per year by 2027/28. 
• Residential, not connected with a CV of $1 million:
  The levy will begin at about $21 in 2024/25 and increase to about $84 per year by 2027/28. 
• Commercial not connected with a CV of $1 million:
  The levy will begin at about $31 in 2024/25 and increase to about $125 year by 2027/28. 

This levy is separate from regular rates and will gradually increase over the construction period, which we expect to be complete in 2026.

Project milestones

October 2020: Wellington City Council was presented with a preferred option for a sludge minimisation facility. In reaching the preferred option, Wellington Water considered a range of viable options for the new plant, to be located at either Carey's Gully at the Southern Landfill, or at Moa Point. They then worked with representatives from Wellington City Council, mana whenua, and local and international technical experts to identify a preferred option.

Late 2020: Wellington City Council began actively engaging with the local community about the project.

June 2021: We consulted on the project and the use of the Infrastructure Funding and Finance Act 2020 (IFFA) to finance it through the Long-term Plan process.

April 2022: We again sought ratepayer feedback on the use of the IFFA to finance the development of the new facility.

June 2022: Business case approved.

August 2022: The Council considered options for an IFFA levy proposal to fund the facility, including levy design options, ahead of a potential decision to submit a levy proposal in December.

Mid-August to late-September 2022: Submissions open on the Notice of Requirement for an alteration to Designation 58 (WCC6 under Proposed District Plan) for the construction, operation, and maintenance of a new Sludge Minimisation Facility (SMF) at 127 and 141 Stewart Duff Drive.

December 2022: Construction approved.

May 2023: Works begin on site for the construction of the facility.

November 2023: Hillock removed.

November 2023: Piling works began.

November 2023: The Outline Plan of works approved with no requests for change.

Mid-2024: Commencement of levy payments via rates bills as a separate line item.

Mid-2026: Expected completion date.

Updates

Read the latest news and updates and follow the progress of the construction through images and video.

Contact us

If you have queries or concerns about the day-to-day construction work at the site, call our construction team.
Phone: 0800 796 525.