A well used for drinking water, near Woodbourne defence base in Marlborough, has tested above safe levels for firefighting foam contamination.
The RNZAF Woodbourne Airbase near Blenheim. Photo: RNZ / Tracy Neal
This is revealed in the latest report on the Defence Force's contamination of groundwater, surface water and soil with toxic PFAS chemicals.
Read the full report (PDF: 0475KB)
The drinking water well returned progressively worse results over five lots of tests since late 2017.
Two per- and poly-fluoroalkyl substances - PFOS and PFHxS - were found in a concentration in a private well that "exceeded the drinking water guideline in this round of sampling for the first time", the consultant's report said.
This was at the eastern edge of the base.
Other private wells have exceeded the drinking water threshold in previous tests.
The so-called "forever chemicals" - because they break down very slowly - have also compromised water bores at Ōhākea in Manawatū, and have polluted Ngataringa Bay at Devonport and areas around other Defence bases and petrochemical plants in Taranaki.
PFASs are categorised as a "possible" carcinogen, and featured in the movie Dark Waters about a fight over Teflon in the US that resulted in a massive settlement.
The Woodbourne report provides the first test results from two new wells drilled by Defence that allow for testing water at multiple levels down to 17 metres; one is at the eastern boundary of the base, the other at a road reserve 2km east.
Similar deep, multi-level wells are about to be drilled at Ōhākea, south of the base where the contamination plume is expected to keep spreading for decades.
At Woodbourne, at the well furthest from the base, PFAS contamination intensified the deeper they went; the other well showed the opposite - it was worse in shallower soils. It is not clear why.
The October report also gives shallow-well results for PFOS and PFHxS, and these are similar to or lower than results two years ago.
At Doctors Creek, though, where the only surface level sample was taken, it was higher than in 2018 but below guidelines.
A Defence Force spokesperson said the result for the sum of PFOS and PFOA of 0.072ug/L was 2ppt above the Ministry of Health drinking water guideline of 0.07ug/L.
It would not say whose well it was "to protect the privacy of individuals", but confirmed they had been told about the results. It is continuing to investigative testing on wells downstream from the Woodbourne base.
The spokesperson said NZDF offered alternative drinking water to all households where test results exceeded 0.06ug/L.
"The consultants have not offered an explanation for the results rising across five lots of tests because they do not have an explanation," the spokesperson said.
"Test results in each of the many wells NZDF have been sampling since 2018 vary significantly over time. Changes in concentration (upwards or downwards) are not currently well understood but it is clear that water level in the aquifer does affect concentration of PFAS in the samples. Any apparent "trend" may simply be an artefact of the timing of the sampling events."
The interim health guidelines New Zealand relies on are the same as Australia's; they are stricter than in many countries, but a lot looser than in some US states that have more intense exposure to PFAS due to large defence bases or industries that have been polluting with them since the 1950s.
New water scheme for Ōhākea
The investigations nationwide here have cost the government millions of dollars, without remediation being addressed except of the water supply at Ōhākea, where a piped water scheme is about to be built, five years after contamination was found there.
The Defence Force bought one of the worst-hit farms south of Ōhākea. It told RNZ this was not due to contamination but "to expand the airbase".
"The area will be necessary because the P-8 Poseidon maritime patrol aircraft are to be based at Ōhākea and general operational tempo has increased."
Regional councils now face most of the burden of monitoring for PFAS and taking any enforcement action.
Low-level PFAS contamination in water is widespread, being discovered many kilometres away from what are considered prime sources, such as firefighter training sites.
A clampdown globally on three types - PFOS, PFOA and PFHxS - has led companies to switch to other forms (and there are 3000 plus to choose from), even though little is known conclusively about the health or environmental impacts of any of the manmade chemicals.
Some research indicates that exposure to PFAS could make catching Covid-19 worse.
Other research suggested the chemicals might continue to leach into landfills even after being cleaned up, so it would be ideal to develop a ready method to destroy it entirely.
The Defence Force said it had not received any advice this year that materially changed its assessment of the risks from PFAS.