A landfill near Porirua City is releasing high levels of a potentially lethal chemical, a report leaked to Radio New Zealand shows.
Residents living near the tip, who have been complaining about a strange smell for years, say the report finally confirms their fears.
Spicer Landfill sits tucked away in a valley behind Tawa in Wellington's northern suburbs, near Kenepuru Hospital.
Since the middle of last year there has been a jump in the number of complaints about smells coming from the tip, with the Wellington Regional Council saying the odours have a significant impact on the environment and local community.
The report leaked to Radio New Zealand was prepared by AECOM Consulting for Environwaste, which runs the tip for Porirua and Wellington City Councils.
It found an exceptionally high concentration of hydrogen sulphide in the gas at the landfill, and said that was unusual, and dangerous to operators at the tip.
Tawa resident Phillip Doomen lives about a kilometre from the site.
He said the gas smell comes and goes but, when it was bad, it made people very unwell.
"I've been out gardening and I've had to come inside because I feel sick. We've had to abandon barbecues on the deck because both my wife and I feel sick, and we know others feel like this too."
Mr Doomen said it was a huge relief to finally have documentation that proved what residents have been complaining about for years, and he felt furious with the council.
"I feel they've been lying to us. They keep saying we've been doing everything we can - I mean it clearly shows they are not following their own guidelines, let alone the other best practices that would seem to be normal for operating the tip."
Ongoing legal action
Envirowaste and Porirua City Council are locked in a legal dispute over an abatement notice served for a resource consent breach for offensive and objectionable smells.
The council's acting general manager of assets, Geoff Marshall, said it couldn't comment on the report because of that court action.
"The report is confidential. It was prepared in the context of proceedings before the Environment Court, so we can't comment on it other than to say that [Porirua City Council] is taking its own expert advice on the issues that were raised in that report.
"There are matters in the report that council doesn't necessarily agree with and we're working on those, and they are the subject of ongoing discussions."
Mr Marshall said the council had been doing a lot of work to try to mitigate the smells.
He said new gas capture wells had been installed at the site, and more clay was being put on top of the landfill with the working tip-face covered at night.
"We planted some trees on the Tawa boundary; that's more of a long-term response. We've installed some extra deodorant spray machines at the landfill. There's now four of them - two of these are mobile so they can be moved around to where the smell is coming from."
Wellington Regional Public Health issued a statement telling residents that physical symptoms like nausea and headaches could be caused by low levels of chemicals in gases.
It recommended anyone concerned about the symptoms should see a doctor.