Food bins, compost or worms?
Wellington’s Southern Landfill is expected to reach capacity within five years, and is in the process of being expanded, so what is taking up all the space? Amber-Leigh Woolf reports.
‘‘When that food waste goes to landfill, it creates methane – a greenhouse gas.’’ Paul Evans, of WasteMINZ
Kerbside bins for food waste, home composting and household worm farms will be trialled across Wellington in a council-led project to divert the amount of leftovers being sent to the city’s landfill.
Food waste represents about a third of what Wellington residents send to the dump, where it festers among the plastic.
But this summer, Wellington City Council’s waste management team will hold an organics diversion trial that will examine the pros and cons of several methods for combating this.
The options are a kerbside collection of food scraps, a predator-free home compost kit for residents, worm farms or another home-based system that has yet to be chosen.
About 500 homes will receive the kerbside collection service while between 100 and 200 properties will trial the other options.
Council waste operations manager Emily Taylor-Hall said the project was still in the ‘‘design’’ phase. But those taking part would be set up with everything they needed – be it compost bins, information, worms or support – during the trial.
‘‘We’re going to work really, really closely with Predator Free Wellington and we’ll work really hard with them around predatorproofing the compost bins,’’ she said.
‘‘Our intention is to give everyone the support and information that they need. We’ll contact every resident who’s part of the trial and potentially give people a home visit to ask how their method is going.’’
Food waste audits of the Wellington region from 2014 showed households disposed of 3.2kg of food waste per week, on average.
Auckland is already rolling out a food waste collection, while in Christchurch and Timaru, both food scraps and green waste can be disposed of in a kerbside bin.
Estimated prices for such collection services ranged from $60 to $80 per annum per household, she said. But the trial would be at no extra cost to ratepayers, with the money coming from existing council budgets.
‘‘In addition to the collection, a food waste processing plant would need to be established.’’
The intention to investigate new options for food waste was approved recently in the council’s Long-Term Plan.
Mike Mendonca, the council’s chief resilience officer, said it needed to be absolutely sure a food waste management scheme would work. ‘‘For it to be successful, we need to be able to make compost that people will buy.’’
WasteMINZ chief executive Paul Evans said Wellington was not the only council wrestling with problem of food waste clogging up landfills. In the case of Auckland, they discovered about 45 per cent of household waste in rubbish bins was food, he said.
‘‘When that food waste goes to landfill, it creates methane – a greenhouse gas.’’
Methane was more harmful than carbon dioxide created by composting. Food waste had a lot of nutrient value but when it was sent to landfill, that value was lost.
The Government had set a zero carbon goal by 2050, and reducing food waste to landfills was going to be an important part of moving towards that, he added.
At Wellington’s southern landfill, seagulls live the dream as they watch fresh refuse get dumped on a daily basis.
About a quarter of it is the food scraps they are hanging out for.
Sewerage sludge also arrives every morning – about 20 per cent of the landfill’s total waste can be described as such.
It’s followed by fresh rubbish, plastic and packaging, all of which is compacted down and covered.
Plastic milk bottles, shopping bags, yoghurt containers and takeaway packaging spotted about the place give the landfill its colour.
Every day, workers traverse the tip face to collect rubbish that has blown free. Last year, they found an old plastic bag from a grocery store that closed down in the 1970s.
‘‘Obviously it’d had a life in the landfill ... but it was still in tact,’’ waste operations manager Emily Taylor-Hall says.
Landfill operations manager Darren Hoskins says people see landfills as a negative thing. But the southern landfill is doing more than others to divert waste to other places.
‘‘We’re doing really well for the amount of materials that we’re diverting, and the amount of resources we’re using to keep things out of the landfill.’’
Some green waste and commercial food waste is diverted into compost operations. The landfill also watches its emissions, Taylor-Hall adds.
They collect and destruct gas though an electricity generator, reducing emissions along with their financial liability.
Every day, about 300 people visit the transfer station to dump their unwanted goods – old mattresses, dilapidated furniture, office desks and shelves included.
On a busy day, more than 800 vehicles come throuhg.
But staff intervene if there are items that can be salvaged, she says.
‘‘Our transfer station is staffed with a member of our team who engages with residents dropping off waste, to see if any of their items can be recycled or resold in our Tip Shop.’’
Contractor staff who work within the drop-off pit also look to recover items where they can.
BUT IS IT ALL RUBBISH?
Wellington households have been called some of the worst recyclers in New Zealand.
At the southern landfill, 18.5 per cent of what arrives could have been included in kerbside recycling or easily recycled elsewhere.The worst offender is paper.
About $23.5 million has been budgeted over the next 10 years for the landfill’s extension. The funding was brought forward because it is expected to reach capacity in five years.
Not all Wellingtonians may realise their sewerage – processed as biosolids – also ends up at the landfill.
Wellington’s sewage goes through a ‘‘dewatering’’ process above Owhiro Valley to remove liquids from solids. Liquids are sent to the Moa Point sewage plant, but the solids get buried at the landfill.
In March, it was found the ratio of rubbish to sewerage was not keeping pace with what Wellington sent down the toilets. A high ratio could make the landfill too sludgy and unstable. Taylor-Hall says the ratio continued to be a"fine line’’ that they walked to stay within their consent.
A document known as the Wellington Region Waste Management and Minimisation Plan outlines how city infrastructure may evolve to cope with waste by 2023.
It proposes finding new ways to use the sludge before it gets to the landfill.
By 2020, councils want to have collaborated with utilities company Wellington Water and others to divert biosolids from the southern landfill to be reused, recovered or recycled.
Wellington City Council’s Long-Term Plan has pinned $34m for sludge treatment options. WasteMINZ chief executive Paul Evans says household rubbish is just a fraction of what is heading to landfills across the country.
‘‘The general public, when they think about what rubbish goes to landfill, they think about what they put out and what they put out in their bins and bags,’’ he says.
‘‘But the rubbish collection is only a component of what goes to landfill. The total amount of [rubbish] put in bins is only 15 to 20 per cent of what goes to landfill. The other 85 to 80 per cent is from the commercial sector and the largest part is from demolition and construction waste.’’