Big dump: new landfill needed for Auckland's 'number twos'

Sunday, 7 December 2025

Auckland’s Poo Island is getting full: so Watercare organised a faeces-focused fun day out in Māngere, part of a meticulously-planned public engagement programme over the future of the supercity’s “biosolids”, reports Jonathan Killick.

For a decade, Watercare has been telling the public that it is “rehabilitating” and “restoring” the once-quarried Puketutu Island in Auckland’s Manukau Harbour. What made that PR narrative so attractive was that they were doing it with a waste product - human faeces.

To this reporter, the idea has always conjured images of native plantings, with human guano spread out like fertiliser, creating what the council organisation aspires one day to be a regional park.

But those illusions were shattered last weekend when Watercare for the first time gave the public a glimpse of its work on Puketutu in what was billed as “Māngere’s big day out”.

It turns out that, hidden behind several layers of gates and fences, and atop the island’s maunga is what appears to be a full-scale landfill, with scores of diggers and trucks burying what is a “seriously” toxic material.

Our group was not allowed to open the windows of our tour bus, let alone get out and walk around, and before departing, the vehicle had to be sprayed down with disinfectant by a mobile car wash.

It’s a reality that Watercare’s strategic relations manager Moana Williams now has to communicate to the public, because buried within that landfill is a hard truth.

Metropolitan Auckland produces 400 tonnes of “biosolids” a day, and the big hole on Puketutu we’ve been dumping it into is getting full, Williams told the Sunday Star-Times.

Within the next 10 years, the city is going to need to find a new repository, and any solution is going to require at least that long to get built. It means a conversation “urgently” needs to be held with Aucklanders, said Williams.

“Everybody flushes and forgets, but we all have a responsibility for our waste,” she said.

And so, while a faeces-focused fun day out with face painting and an ice rink might seem like a Norovirus-induced fever dream, it was actually the result of a meticulously planned public engagement.

Williams says Watercare wants to hear from the public about its priorities for waste disposal because the solution will invariably end up having to balance cost with the environment.

At this stage, she said, there are two realistic options. Either another landfill is built in a new location, or the city builds an incineration plant, which would be the first of its kind in New Zealand.

What is a biosolid?

The Star-Times visited Māngere ’s wastewater treatment plant to get a first-hand sniff of the issue.

Since the opening of the Central Interceptor, a giant sewage pipe which runs through the city’s central isthmus, 87% of the city’s waste has been piped to the site.

Engineer Chris Sinclair explains that it runs through a treatment process not unlike the human intestines, where it effectively gets a “second digestion”.

Just like a human, it needs to be kept healthy and can’t be under or over-fed.

A bubbling cauldron of bacteria is heated to human body temperature, allowing micro-organisms to consume nutrients from the waste. The leftover forms biosolids, which settle on the bottom.

Those are then collected, de-watered in a centrifuge and treated with lime and ultraviolet light, turning it into a fine, powdery soil-like substance.

Sinclair said that in the old days, the city gave away biosolids as fertiliser to residents who turned up with trailers.

But that can’t happen now: not just because health and safety regulations would never allow such exposure to potential pathogens, but because 25% of Auckland’s wastewater is industrial and that means toxic heavy metals.

In fact, said Sinclair, “everything that goes down the drain ends up here”.

There’s a conveyor belt at the plant that removes foreign objects - usually sanitary products, wet wipes and “fat-bergs” - and it can get yucky.

Sinclair recalled hosting a tour at the plant when “an abattoir must have dumped a whole bunch of offal, and it was pretty disgusting”.

A serious conversation about our poo

The point that Williams really wanted to hammer home is that the waste is not a simple material to dispose of. Hence the need for public education and consultation.

At the Māngere fun day a jar of biosolids was on display, and Watercare staff were aghast when I picked it up for a photo, telling me that if I dropped and smashed it, the town centre would have to be evacuated.

The event was hosted by ambassador Jack Bourke - who in addition for working for a project management consultancy is famous for being a TV judge on Pacific Island TV show called Digicel Stars.

“I was coined the Simon Cowell of the Pacific, but I wasn’t mean, I was just honest,” he told the Star-Times.

Bourke remembers growing up in South Auckland and “experiencing the unique stench of Māngere,” when it was home to sewage oxidation ponds.

“We all thought it was a by-product of the Manukau harbour, but now we know it was waste treatment.”

The suburb has borne the brunt of Auckland’s effluent infrastructure needs and this time Watercare is determined to ensure locals’ priorities are taken into account.

“We decided we are going to do it once and do it big, and do it Māngere … to talk specifically about our number twos and listen to what they have to say.

“For me its whatever is best for the environment, and of course there is cost questions but we’ve got to think of the generations ahead of us, and what our grandchildren inherit.”

Picking a site for a future landfill facility or incineration plant won’t be easy, with planning restrictions and residents’ reactions both inevitably creating challenges.

Trucking tonnes of “odorous” material daily is also a logistical consideration that lends itself to being a close to Māngere as possible.

But a new solution must be found, because even if Watercare used all of Auckland’s existing landfill capacity in the 2030s, it would still be left with 80,000 tonnes.

At the fun day, locals were given two tokens and asked to choose from priority boxes labelled environment, reuse, cost, efficiency and community disruption. At a glance, they appeared equally full.

Watercare researcher Jenny Wigley believes there “is an opportunity to do something better than throw it away, but there’s only so much people are willing to pay”.

“A Dome Valley [regional landfill] filled with biosolids would be a travesty,” said Wigley, “but a Waihi mine that’s totally contaminated could be filled.”

“You never know what will happen with political wheeling and dealings, but we can say to the public ‘it’s your bill money, what do you want done with it?”

So next time you’re scrolling on your phone on the loo, maybe you can do Watercare a solid and have your say on the future of Auckland’s waste disposal.

“It’s everyone’s business.”