Proposed extension to the Southern Landfill

With only four years left until the current stage of the Southern Landfill is full, we’ve been busy testing our assumption that extending the Landfill is the most viable solution, by assessing alternative waste management technologies.

Landfill aerial to sea image

Latest update: November 2019

The assessment concluded that extending the Landfill remains the most viable solution for now.

This reflects that good practice landfill design, construction and operation is well proven in New Zealand, that there is a relatively low environmental risk with appropriate design and operation and that the cost of the Landfill extension is relatively low compared to other options. 

Waste management alternatives assessment (2.2MB PDF)

Current situation

The Southern Landfill is a critical piece of sanitation infrastructure for Wellington. We accept waste from kerbside collections, commercial collections and materials delivered by residents and businesses to the on-site transfer station.

The Southern Landfill is the only facility in Wellington City that accepts special waste including all the City’s dewatered sewage sludge, contaminated soil and asbestos containing materials.  The existing disposal area will likely reach capacity as early as 2023.

Waste generation is projected to rise in line with population and GDP growth.  The Landfill itself does not generate waste; waste minimisation begins well upstream of the Landfill. Wellington City Council is committed to reducing the amount of material landfilled by 30 per cent by 2026.  The Landfill is just one part of the waste picture, which includes carbon.

How we evaluated the waste management alternatives

We identified a range of values we thought would be important to consider when we evaluated the waste management alternatives, and we asked the community to rank these in order of importance. These were then considered alongside Council priorities.

The values included community impacts/values, environmental, technology risk, financial, legislative/Resource Management Act and product risks.

Options for managing waste

We considered a range of options for managing waste in Wellington City. 

The options we assessed included:

1. Closure of the existing Landfill – Waste no longer accepted at the Landfill.  Waste will need to be transported directly to another landfill by collection companies, households or businesses, most likely Silverstream Landfill (Lower Hutt) and/or Spicer Landfill (Porirua).

2. Closure of the existing Landfill and continued operation of the transfer station – Waste accepted at the transfer station with material transferred to another landfill by Council, most likely Silverstream Landfill (Lower Hutt) and/or Spicer Landfill (Porirua).

3. Extension of the existing Landfill – Development of Stage 4 of the Landfill by 2023 to allow ongoing disposal of waste.

4. Conventional (mass burn) incineration – Treatment of waste through conventional incineration with rejects, bottom ash and air pollution control residues disposed of in a new dedicated stage at the Landfill.

5. Advanced thermal treatment:

  1. Gasification – Treatment of waste through gasification with char, air pollution control residues and rejects disposed of in a new dedicated stage at the Landfill.
  2. Pyrolysis – Treatment of waste through pyrolysis with char, air pollution control residues and rejects disposed of in a new dedicated stage at the Southern Landfill.

6. Mechanical heat treatment (MHT) – Treatment of waste through MHT with heat treated material and residue disposed of in a new dedicated stage at Southern Landfill.

7. Mechanical biological treatment (MBT) – Treatment of waste through MBT with stabilised biodegradable material and residue disposed of in a new dedicated stage at the Landfill.

Our assessment of these options assumes that the current range of initiatives to reduce waste generation and capture materials for reuse, recycling or recovery continue. Current initiatives include:

  • Education to encourage Wellington City residents and businesses to avoid the generation of waste.
  • Provision of a kerbside recycling collection service for residential properties in Wellington City.
  • Accepting reusable items at the Southern Landfill’s Tip Shop
  • Providing free recycling and discounted green waste drop off at Southern Landfill.
  • A range of commercial recycling and recovery services including paper, cardboard, food waste, green waste, metals, e-waste and plastics.

Options evaluation

The evaluation suggests that option 3: Extension at the Southern Landfill, option 2: Close the Landfill and continued operation of the transfer Station at Southern Landfill and option 1: Close the Southern Landfill are the most favourable options.  The remaining options received less favourable scores for legislative/Resource Management Act risks, product risks, technology risks and financial impact. 

Option 3: Extension at the Southern Landfill has the most favourable score for cost while options 2 (transfer station at Southern Landfill) and 1 (closure of the Southern Landfill) benefit from favourable legislative/Resource Management Act scores.  Costs are high for options 2 (transfer station at the Southern Landfill) and 1 (closure of the Southern Landfill) due to the cost of transporting and landfilling 15,000 tonnes per year of biosolids elsewhere and the loss of generated revenue.

On balance option 3: Extension at Southern Landfill is the most favourable option with cost and product risk (ability and willingness of other landfills to accept all of Wellington City’s waste) helping to differentiate between the top three options.

What next?

We are now commissioning technical studies to help with the design of the Landfill extension and to support our resource consent application that will be lodged in 2020.

We’re suggesting the following studies:

  • Air:
    • Odour and dust
    • Landfill gas generation
    • Noise and vibration
  • Water:
    • Aquatic ecology
    • Hydrogeology
  • Land:
    • Geology and geotechnical
    • Contaminated land
    • Terrestrial ecology
    • Landscape
  • Road:
    • Assess impacts on traffic in and around the site
  • People:
    • Cultural values assessment
    • Archaeology

Want to know more?

We’re seeking views from the community over the next few months.

During our next drop-in sessions, we’re seeking any information that could help us with the proposed technical studies.

For more information and to have your say go to: https://www.letstalk.wellington.govt.nz/southern-landfill-future

If you’d like to know more about this project email us at Landfill@wcc.govt.nz to go on our update list or call us on (04) 499 4444.

Or drop-in to one of the following sessions:

Date

Time

Where

Address

Sunday 1 December

11am to 1pm

Brooklyn Community Centre

18 Harrison Street

Sunday 1 December

2pm – 4pm

Ōwhiro Bay School Hall

96 Happy Valley Road

Tuesday 3 December

11.30am – 1.30pm

Facebook Live Q&A

Wellington City Council Facebook Page

Tuesday 3 December

4.30pm – 6.30pm

Penthouse Cinema

205 Ohiro Road

Wednesday 4 December

11.30am – 1.30pm

Wellington City Council

Level 16, 113 The Terrace