Carey’s Gully Composting Operation To Change
Change is afoot at Wellington City Council’s composting facility at Carey’s Gully (the Southern Landfill). The Council
has announced it is to discontinue the conversion of sewage sludge into compost at the site.
The Council has decided to halt the existing composting operation when its contract with the facility operator - Living
Earth Ltd – terminates at the end of 2008. The principal reasons for the closure are:
Increasing costs associated with running the plant
The lack of a viable market for the compost
Difficulties in eliminating the smells
The advent of new alternative and sustainable ways of dealing with the sludge.
Smells periodically generated by the sludge processing operations have been at the centre of continuing complaints from
residents in Brooklyn and nearby southern suburbs.
Councillor Celia Wade-Brown, the Council’s Environment Portfolio Leader, says the Council is looking at a number of
alternatives to composting the sludge. This includes a possible regional joint-venture with Porirua City – in which the
sludge from both cities could be artificially dried to greatly reduce its volume and then used to generate gas which, in
turn, can generate electricity.
She says the news will likely be welcomed by residents neighbouring Carey’s Gully.
“We are acutely aware that the compost plant and associated infrastructure, including the sewage sludge dewatering
plant, have been sources of odour since they opened almost 10 years ago.
“We have worked with Living Earth and other operators for a number of years in a bid to reduce the smells – however it
has not been possible to adequately reduce odour and we know this has not been to the satisfaction of our neighbours.”
The composting plant, which cost $17 million to build, has processed some 130,000 tonnes of dewatered sewage sludge from
the Moa Point and Western (South Karori) treatment plants and has produced some 25,000 cubic metres of compost a year.
Cr Wade-Brown says that prior to the construction of the Moa Point and Western treatment plants, “all of that sludge
would have ended up in Cook Strait. The removal of this vast amount of human pollution has transformed Wellington
Harbour and the South Coast – for the better.
“It’s disappointing the sludge-composting operation has not been the success it was hoped to be when first mooted as
part of the then-leading edge Clearwater sewage treatment scheme in the mid-1990s.
“However technology and waste-disposal thinking has progressed considerably – even in the past decade. There are new,
more environmentally sustainable means of disposing of the sewage sludge and we have already started work to look at the
best option for Wellington City.”
Mike Mendonca, Manager of Wellington City Council’s CitiOperations unit which runs the Southern Landfill, says the
Council still intends to run a composting operation at the Southern Landfill – this will deal with the 3000 tonnes of
green waste brought to the landfill each year, along with the increasing amounts of food waste from Wellington
restaurants and other food premises being collected as part of the ‘Kai to Compost’ scheme.
And Mr Mendonca says the Council will actively investigate options to encourage more green waste and food-waste
recycling. He says an enormous amount of garden waste, vegetable cuttings and other food scraps go into the landfill at
the moment. “If we can reduce that waste stream then we’ll extend the life of the landfill and still be able to produce
top-quality compost.
“This will also address the issue of methane production from the landfill. The less green waste that is composted
instead of landfilled, the less methane is produced.”
The City Council will immediately start discussions with Living Earth Limited about the transition away from processing
sludge through the composting plant.
Mr Mendonca says nearby residents can expect the odour situation to improve over the next year.
ENDS