Decision 7 - A solution for reducing sewage sludge and waste

Consultation has concluded

Much of our waste at the Southern Landfill is wastewater (sewage) sludge - about a quarter of the waste entering the landfill.

We actually need other waste to mix it with, so until we do something different with sludge, the landfill will grow at a faster rate than we’d like. We want to reduce carbon emissions and waste by a third. Minimising sludge is the first step.

What's the background to this decision?

Through our Te Atakura: First to Zero plan and our Regional Waste Minimisation and Management Plan

We need to break the link between the Southern Landfill and wastewater sludge and stop pumping sludge across the city, as 2020 highlighted the serious resilience issues and the significant consequences of failure.

There are four options

Option 1:
No change in current practice
Option 2:
Invest in technology at Southern Landfill
Option 3:
Sludge minimisation through Council funding
Option 4:
Sludge minimisation through alternate funding (preferred)
The cheapest course of action would be to keep pumping raw wastewater across the city and disposing of it in the landfill. This is a feasible and affordable choice.

We could invest in better infrastructure at the Southern Landfill. For example, we could install a thermal drier (estimated additional total expenditure around $86-134m) and this would go some way to reducing the volume of sludge to be disposed.

This option reduces some of the sludge volume to landfill, but leaves a significant remaining volume of sludge to be disposed of at the landfill. In addition, the pumping of sewage across the city would continue.


In option 3 we Invest in the existing wastewater treatment plant site at Moa Point.
It would mean that sludge would not need to be pumped to the Southern Landfill and would help the city meet its environmental objectives.

Option 3 would be a long-term investment that would better reflect our aspirations on carbon and waste reduction.

Option 4 delivers the same service and benefits as Option 3. However, this option is our preferred option, because the cost of the project will be delivered and funded through an external fund enabled by the Infrastructure Funding and Financing Act 2020 It means that the project would not be funded by Council debt and we would not exceed our debt-to-income cap as in Option 3.

The same asset will still be constructed as Option 3 (at a value of $147m-$208m)
Capital cost and debt impact: No change
Capital cost and debt impact: $86m to $134m
Capital cost and debt impact: $147m to $208m in first 10 years
Capital cost and debt impact: Same as Option 3, but through alternate funding, so no cost to Council.
Rates change: None
Rates change: 0.39% 3 year average increase
Rates change: 1.65% 3 year average increase
Rates change: None, but a levy of approx. $70 to $100 per residential ratepayer collected per year from year 4


These options have pros and cons, and are outlined in more detail here

Our preferred option

The Council prefers Option 4, Sludge minimisation through alternate funding. Reducing carbon emissions and reducing waste by a third. Minimising wastewater sludge and reducing waste by a third is a required first step to achieving both Te Atakura (zero carbon plan) objectives and the Regional Waste Minimisation and Management Plan.

Note: Our external Auditors have made specific comment on the sewage sludge decision in their opinion in the consultation document - see pages 72-74 of the consultation document available at the link below.


Want to know more about another Decision? Head back to our Long-term Plan homepage or read our full consultation document

Or, are you ready to have your say? Head to our Long-term Plan submission form

Much of our waste at the Southern Landfill is wastewater (sewage) sludge - about a quarter of the waste entering the landfill.

We actually need other waste to mix it with, so until we do something different with sludge, the landfill will grow at a faster rate than we’d like. We want to reduce carbon emissions and waste by a third. Minimising sludge is the first step.

What's the background to this decision?

Through our Te Atakura: First to Zero plan and our Regional Waste Minimisation and Management Plan

We need to break the link between the Southern Landfill and wastewater sludge and stop pumping sludge across the city, as 2020 highlighted the serious resilience issues and the significant consequences of failure.

There are four options

Option 1:
No change in current practice
Option 2:
Invest in technology at Southern Landfill
Option 3:
Sludge minimisation through Council funding
Option 4:
Sludge minimisation through alternate funding (preferred)
The cheapest course of action would be to keep pumping raw wastewater across the city and disposing of it in the landfill. This is a feasible and affordable choice.

We could invest in better infrastructure at the Southern Landfill. For example, we could install a thermal drier (estimated additional total expenditure around $86-134m) and this would go some way to reducing the volume of sludge to be disposed.

This option reduces some of the sludge volume to landfill, but leaves a significant remaining volume of sludge to be disposed of at the landfill. In addition, the pumping of sewage across the city would continue.


In option 3 we Invest in the existing wastewater treatment plant site at Moa Point.
It would mean that sludge would not need to be pumped to the Southern Landfill and would help the city meet its environmental objectives.

Option 3 would be a long-term investment that would better reflect our aspirations on carbon and waste reduction.

Option 4 delivers the same service and benefits as Option 3. However, this option is our preferred option, because the cost of the project will be delivered and funded through an external fund enabled by the Infrastructure Funding and Financing Act 2020 It means that the project would not be funded by Council debt and we would not exceed our debt-to-income cap as in Option 3.

The same asset will still be constructed as Option 3 (at a value of $147m-$208m)
Capital cost and debt impact: No change
Capital cost and debt impact: $86m to $134m
Capital cost and debt impact: $147m to $208m in first 10 years
Capital cost and debt impact: Same as Option 3, but through alternate funding, so no cost to Council.
Rates change: None
Rates change: 0.39% 3 year average increase
Rates change: 1.65% 3 year average increase
Rates change: None, but a levy of approx. $70 to $100 per residential ratepayer collected per year from year 4


These options have pros and cons, and are outlined in more detail here

Our preferred option

The Council prefers Option 4, Sludge minimisation through alternate funding. Reducing carbon emissions and reducing waste by a third. Minimising wastewater sludge and reducing waste by a third is a required first step to achieving both Te Atakura (zero carbon plan) objectives and the Regional Waste Minimisation and Management Plan.

Note: Our external Auditors have made specific comment on the sewage sludge decision in their opinion in the consultation document - see pages 72-74 of the consultation document available at the link below.


Want to know more about another Decision? Head back to our Long-term Plan homepage or read our full consultation document

Or, are you ready to have your say? Head to our Long-term Plan submission form

Consultation has concluded

Do you have a questions on reducing sludge and waste?

Check the FAQ's above on the right of this page as well as other questions below - your question may already have an answer.

Please be concise and respectful in asking questions - we will do our best to respond promptly - often by the next working day. Some answers may however take a bit longer to get the details right. We monitor the site from 8:30am - 5pm Monday to Friday 

  • On terms of waste, is there a likely possibility of incineration of waste, like what happens in Sweden, Denmark and many other Nordic and Scandinavian countries, as well as Japan, to reduce waste, provide energy to their communities and also create employment, as well as reduce our impact to the environment. The left over Ash could be used as filler for cement, asphalt, etc. I know that there's a lot of resistance and outright refusal to consider this, but if the nations I've mentioned are shown as places that we should look at for guidance, then surely incineration of waste is a goer.

    ALofPalmyviaNewtown81 asked almost 3 years ago

    Kia ora ALofPalmyviaNewtown81, 

    Thanks for the question. The response below is from our waste team.

    We have looked at this as part of the extension of the landfill and as part of the sludge minimisation work.

    While it's technically feasible, as you can see from the analysis there are issues around consentability and primarily the economics of one of these plants.  

    It’s definitely an option, but bear in mind the drivers are different on those parts of the world, where there are high landfill taxes and a lack of space for landfill.  And to be honest, we would greatly prefer to focus on reducing waste in the first place instead of making it more convenient to dispose.  If we can find a better option for sewage sludge we think we can really start to minimise other waste in Wellington City.

    Nga mihi

    Amy

  • What do large European cities that are landlocked do with their wastewater sludge and is there much testing done on the sludge to check for toxins and heavy metals etc ?

    ChrisL asked almost 3 years ago

    Kia ora ChrisL,

    We haven’t specifically looked at landlocked countries.  But below is a summary of technologies from around the world that were considered at the start of options analysis.  The EU has strict regulations around adverse effects on the environment, which is one of the reasons that waste to energy is popular in that part of the world – basically this technology destroys the problem although there is always some amount of residual waste that needs to be carefully disposed.

    Appendix-B-Sludge-Treatment-Process-Technologies-Overview2.pdf (wellingtonwater.co.nz)


    Nga mihi, 

    Amy

  • Option 4 - are you saying that after year 4 each ratepayer will pay $70-$100 per year forever more?? I think you may need to explain that better in the options.

    susiecampgirl asked about 3 years ago

    Hi Susie,

    If the proposal goes ahead and we are successful in securing the Special Purpose Vehicle, the levy will be collected for 30 years. 

    Cheers, 

    Amy

    sludge,finance
    sludge finance