Regional councils suspect thousands of tonnes of contaminated waste are being buried on farms every year – but there’s little they can do about it.
Most of the dumping takes place on private land, and councils are left relying on whistleblowers to dob in any illegal activity.
Various regional council surveys have shown an average farm generates between 20-40 tonnes of waste a year. What is not known is how much of that includes hazardous substances and recyclables that are either buried in pits or burned, out of sight and out of mind.
Shaun Andrewartha, of Greater Wellington Regional Council, said: “Farm refuse dumps is something high on my agenda as something we need to look at a little bit closer.
“If they are just chucking it in a hole and not complying with the rules … then they are breaking the law.”
Regional councils are in charge of controlling discharge of contaminants to land, and make the rules for what can and cannot be put in farm refuse dumps.
But Andrewartha admitted councils often relied on being told whether a farmer was dumping illegal substances.
“We don’t have the resources to have a monitoring regime for what’s called permitted activities.”
Greater Wellington officers have investigated dumps and offal pits on nine farms since 2014, but have issued no warnings or infringements as a result.
A 2012 Environment Canterbury (ECan) scoping study found the generation and management of non-natural farm waste was largely unregulated, and there were no specific central or local government work programmes aimed specifically at farm waste.
Team leader contaminated sites Davina McNickel said ECan was currently investigating ways to make it easier for farmers to divert hazardous substances and recyclables through more sustainable channels.
“What we’ve found is that farmers want to do the right thing, but if there is no alternative they’re going to have to burn it or bury it.
“There is a hell of a lot material that’s going in pits that probably shouldn’t.”
A Waikato Regional Council study in 2014 found that 69 farms surveyed generated an average of 37 tonnes of inorganic, organic and household rubbish a year. About 80 per cent of farms had an on-farm dump, and 94 per cent of sites burned waste.
A 2005 Taranaki Regional Council survey estimated that approximately 525 tonnes of plastic wrap, 8750 tonnes of household waste, 32,440 plastic containers as well as more than 100 cubic metres of waste engine and hydraulic oil were generated in the rural region each year.
Masterton District Council has closed two of its four rural dumps in the past few years because of lack of volume, suggesting the vast majority of waste is dumped on-farm.
Assets and operations manager David Hopman said many farmers were not willing to pay to use a dump when they could dispose of rubbish on their farms for nothing.
He admitted estimates of how much rubbish was being dumped on farms were just a “stab in the dark”.
Professor Mark Milke, of the University of Canterbury, who specialises in solid waste management, said there could be various environmental impacts, depending on what was being dumped.
“Household products can have some hazardous materials in them which have the potential to cause damage.
“It’s not appropriate to be taking household waste in modern society and putting it into pits on your property in any unmanaged situation. The risks are too great.”
Wairarapa soil scientist Esther Dijkstra said she was aware that indiscriminate dumping on farms was widespread.
“I’ve got friends who dump everything in [disposal pits] just because they can’t be bothered to go to the tip.”