Sunday, November 28

Decision on the future of the Wellington landfill at a ‘critical point’

Wellington City Council is outlining its options for disposing of the city’s future garbage.

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Consents for the city’s landfill, the South Landfill in Happy Valley, expire in April 2026.

Four options, prepared by engineering firms BECA and Fichtner, include investing in: a waste incinerator, expanding recycling sorting capabilities, a treatment to dry and reduce biological material, or expanding the existing landfill.

A fifth option presented by councilors is to “not dump in landfills”, that is, to allow the landfill to close when their authorizations expire.

The extension of the sanitary landfill is the preferred solution for city council officials.

At City Council meeting agenda document prepared by officers, the extension is described as the most profitable.

Technology options are not easily scalable and are not alternatives to landfills alone.

The extension is on a smaller scale, fitting within the limits of the existing landfill, than a controversial 2019 option that would have expanded the tip hundreds of meters from Zealandia wildlife sanctuary.

And time is running out.

The agenda describes being at a “tipping point” with the “shortest viable time frame to design and implement the future waste disposal facility” before the consents expire.

Council officials recommend starting the design and consent process for the landfill extension immediately.

Councilors will vote next Thursday on what options to bring to the public for comment.

It is unclear if the options will require rate increases.

The council’s current approach to waste requires a landfill to remove sewage sludge; the sludge must be mixed with solid household waste.

The council has already voted to invest in alternative wastewater disposal technology, which should be ready by 2026 and would remove 20 percent of waste going to landfill.

Funding for waste minimization, such as curbside recycling, is economically dependent on revenue from the landfill.

A separate roadmap for waste reduction that the city is working on indicates that it could cut volumes going to the southern landfill in half over the next 15 years.

The council is committed to becoming zero carbon and reducing the amount of waste going to landfill per resident per year from 600kg to 400kg by 2026.

The options

Energy from waste (estimate $ 214 million to build, $ 15 million a year to run. By-product: 25 percent)

It burns the waste and uses the generated heat to produce electricity. Part of the ash produced can be used as a building material. The hot flue gases are treated to remove any contaminants.

Materials recycling plant (estimate of $ 43 million to build, $ 27 million a year to operate. By-product: 85 percent)

It takes a combination of waste materials and sorts them into different recyclable material streams. Leftover non-recyclable material can be sent to landfill or energy from waste.

Mechanical treatment of biological waste (estimate of $ 78 million to build, $ 24 million a year to execute. By-product: 65 percent)

Similar to the materials recycling facility, but with an additional biological treatment step, such as bio-drying, composting, or anaerobic digestion. This material is then classified as in the material recycling facility.

Expansion of the existing landfill (estimate of $ 57 million to build, $ 4 million a year to execute. By-product: -)

The remodel of an existing landfill and is known as the ‘piggyback option’. In this scenario, the waste would be placed on top of a previously dismantled landfill stage. It would give the South Landfill an additional 15-20 year useful life, even longer as waste minimization policies take effect.

‘No landfill’ (loss of revenue collected from $ 17 million tip per year, rates of 2.5 percent likely to increase to cover curbside recycling and other waste reduction initiatives).

This option implies closing the South Sanitary Landfill when consent is exhausted in 2026 and converting it into a reserve or similar. Residual waste from the City of Wellington should be disposed of at other landfills in the region, for example in Porirua or Upper Hutt.

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