In the 2022 Annual Plan, we agreed the best option to extend the life of the Southern Landfill was to create a new landfill on top of an old one. This is known as the ‘piggyback’ option and will help provide a landfill that minimises environmental impact and supports the transition to a circular economy.
About the project
The resource consents for the current operation at Southern Landfill, referred to as Stage 3, will expire in June 2026. About the same time Stage 3 is expected to be full and will need a replacement.
Work on a new landfill commenced back in 2009 and went through an extensive process which led to the consideration of three options. These options were consulted on as part of the 2022 Annual Plan consultation process.
The options put forward were:
- Southern Landfill Extension Piggyback Option (SLEPO)
- Waste to Energy
- No landfill – export waste to another landfill.
Public support for the SLEPO option was 50% versus 24% for Waste to Energy and less than 5% for no landfill. The SLEPO option was selected as the preferred option.
How the landfill is currently managed
The Southern Landfill plays a critical role to the smooth running of Wellington by providing somewhere for waste to be disposed of and promoting resource recovery through waste diversion options including the Tip Shop and Capital Compost.
Each year approximately 125,000 tonnes of materials are received at the Southern Landfill. This includes about 8,400 tonnes of domestic waste, 56,000 tonnes of commercial waste, 14,300 tonnes of sludge, 17,800 tonnes of special waste and 28,300 tonnes of contaminated soil.
Resource consent conditions require sludge (solids produced from the wastewater treatment process) to be mixed with waste at a ratio of 1 part sludge to 4 parts waste. This is expected to change with the planned construction of a new Sludge Minimisation Facility at Moa Point which will significantly reduce the volume of sludge needing to come to landfill. This will also mean Wellington can introduce resource recovery and recycling initiatives that will reduce the volume of other waste.
Resource consents for the landfill contain no less than 97 conditions. Annual audits are carried out by Greater Wellington Regional Council to determine compliance with resource consent conditions.
- Stage 3 of the landfill has less than 4 years capacity left.
- Resource consents for Stage 3 will expire in June 2026.
- Disposal of wet sludge required mixing with waste at a ratio of 1 part sludge to 4 parts of other waste, presenting a barrier to recycling and resource recovery opportunities to minimise the volume of waste to landfill.
- Continued disposal of waste requires a new residual waste disposal solution to be in place by June 2026.
- The preferred solution, SLEPO, requires a new resource consent and associated design and construction works to make this a reality. This requires various technical and environmental aspects to be addressed and considered.
The SLEPO project has been established with three key investment objectives:
- Provide a landfill solution that minimises environmental and social impacts and enables the transition to a circular economy.
- Safely dispose of residual waste from both residents and commercial operators in keeping with best practice and the requirements of the Resource Management Act.
- Be a cost-effective waste management solution.
Key benefits from adopting the SLEPO solution include:
- Waste diversion: The Council can directly influence waste diversion at the Southern Landfill and implement strategically aligned waste reduction and minimisation initiatives.
- Resilience: The Council will have a strategic asset to dispose of large quantities of waste in an emergency event.
- Value for money: This is best value for money to deliver the Council's climate change targets.
- Environmental: Close alignment with delivery of Te Atakura – First to Zero and the Wellington City Council Zero Waste Programme.
What’s happened so far
To arrive at a preferred residual waste disposal solution, Council undertook a comprehensive options analysis and Mana Whenua partner and stakeholder engagement process.
The analysis included approximately 14 different options that either dispose of or reduce the volume of waste. Using key criteria developed with a Working Party representing community stakeholders to assess the various options, a short-list was developed and consulted on as part of the 2022/23 Annual Plan process.
Our preferred option
Following the Public Consultation Process and evaluation of feedback received, Council landed on its preferred option – Southern Landfill Extension Piggyback Option.
As summarised in the Annual Plan 2022/23 consultation document this option offered benefits over the other two options: waste to energy and export to other landfills.
Key reasons in favour of the SLEPO option include:
- SLEPO will be Operational June 2026.
- Disposal to landfill requires no minimum tonnage.
- There will be no service level change.
- Wellington City Council has full control over access to the landfill.
- Provides resilience in the event of an emergency event.
- Will have no impact on rates.