Also known as the ‘piggyback’ option, this extension 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 nearly 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 site 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 for disposal. 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 for the current stage 3 landfill 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 will change with the construction of Te Whare Wai Para Nuku, the new sludge minimisation facility at Moa Point which will significantly reduce the volume of sludge needing to come to landfill. Removing the need to mix waste with sludge will also mean Wellington can introduce more resource recovery and recycling initiatives that will reduce the volume of other waste.
Current issues
- Stage 3 of the landfill has less than 2.5 years capacity left.
- Resource consents for Stage 3 will expire in June 2026.
- Disposal of wet sludge requiring mixing with waste at a ratio of 1 part sludge to 4 parts of other waste, presents a barrier to recycling and resource recovery opportunities to minimise the volume of waste to landfill.
- Continued need for safe disposal of waste requires SLEPO to be in place by June 2026.
Objectives
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.
Benefits
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.
- Environmental: Close alignment with delivery of Te Atakura – First to Zero and He anamata para kore mō Pōneke – the Wellington City Council zero waste strategy.
What’s happened so far
To arrive at a preferred residual waste disposal solution, the Council undertook a comprehensive options analysis and mana whenua partner and stakeholder engagement process.
A short list was developed and consulted on as part of the 2022/23 Annual Plan process.
Funding approval was given by the Environment and Infrastructure Committee when the business case was presented in February 2023.
SLEPO Business Case: Project Business Case (Significant) Residual Waste Disposal (1.37MB PDF)
Resource consents for SLEPO were granted in March 2024, including 200 conditions. Annual audits are carried out by Greater Wellington Regional Council to determine compliance with resource consent conditions.
Preliminary construction works commenced October 2024.