Toxic foam risk ‘complex issue’
A two-year wait before the Government was told of potential water contamination at Ohakea air base was due to the need to develop new testing and safety guidelines for two toxic chemicals, the Defence Force says.
The Defence Force stopped using a particular firefighting foam in 2002 because of concerns about two chemicals, PFOS and PFOA, but many commercial airports still use foams that could be suspect.
Although they used significantly smaller amounts of the firefighting foams, airports around the country have also begun testing for contamination and moving to alternatives.
About 60 properties near the Ohakea air base, and 90 properties near Woodbourne in Marlborough have potentially been affected as buildups of the chemicals run off into the nearby groundwater.
The Defence Force received the first results in 2015, but the Government says it was only brought into the loop in August.
It wasn’t until this month that the Ohakea base’s neighbours were told of the potential contamination risk, and told not to drink water from bores for at least a month while tests were done to make sure it was safe.
The Ministry for the Environment has said the tests are a precaution, and there is no ‘‘acute human health risk’’ at this point.
So far, samples have been taken at three properties near Ohakea, and the Defence Force is waiting to hear back from the other landowners to arrange a convenient testing time. None of the residents have yet taken up an offer of a supply of bottled water.
Defence Force spokeswoman Sue Eden said the contamination was a highly complex and technical issue, which had taken time to figure out.
‘‘There was no New Zealand standard [for PFOS/PFOA] at the time we began our initial tests, and we needed to understand the implications of the concentrations of PFA compounds found.’’
Technical experts were brought in to help develop standards to determine what the safe levels were for both chemicals. This included working with the Australian Defence Force, which is investigating the same issue on a larger scale at 18 sites.
Eden said a second test earlier this year confirmed unacceptably high levels of the chemicals. The Government was brought in to help co-ordinate the response when modelling suggested the contamination had likely spread.
Ministry of Health spokesman Dr Stewart Jessamine said there were no international guidelines on the safe levels of PFOS in drinking water, so the Government has accepted the Australian guidelines, for now.
But even now, most commercial airports were still using a firefighting foam that could be toxic, Airport Association chief executive Kevin Ward said.
It was a trade-off because, despite the foam’s potential harm, it was still the most effective in stopping aviation fuel fires, he said.
‘‘It’s an international problem. The aviation community has been looking to move to more environmentally friendly options, but that’s still an ongoing process.’’
Palmerston North Airport chief executive David Lanham said airport firefighters were switching to a new type of foam, as scientific evidence of the health risks mounted.
‘‘Unfortunately, we can’t just tip it all out. We need something to be ready if there’s a fire or an accident.’’
Lanham said finding an effective replacement was expected to take at least three months. Then the airport would seek advice from the ministry on how to dispose of the foam safely.
There was unlikely to be any significant contamination around Palmerston North, as the airport had used only 200 litres of the foam in 20 years, he said. That’s a fraction of the amount used at Australian and New Zealand Defence Force bases being investigated for contamination risks.
Ohakea used 1000 litres a year, largely in firefighting exercises.
Christchurch Airport stopped using the foam in the early 2000s, but Auckland and Wellington airports reported they were still using it.
‘‘Unfortunately, we can’t just tip it all out. We need something to be ready if there’s a fire or an accident.’’ David Lanham, Palmerston North Airport chief executive