Auckland treatment plant that just got $2m upgrade shutdown due to contaminant

7:36 pm on 2 November 2022
Pumps at the Onehunga Water Treatment Plant. Photo - Watercare

Pumps at the Onehunga Water Treatment Plant. Photo: Watercare/Supplied

Watercare has shut down an Auckland treatment plant after finding a contaminant above drinking water threshold levels.

It has only just spent $2 million upgrading the Onehunga plant.

Watercare posted a statement on its website in mid-October about finding levels of the so-called "forever chemicals" PFAS had been too high on four occasions. RNZ did not see it.

RNZ is asking for the dates, and specific levels, of these high points.

The long-lasting per- and poly-fluorinated alkyl substances are causing ructions worldwide as more research links them to health conditions.

They sparked nationwide investigations of defence bases, airports and fire station training sites in New Zealand from 2018-2021.

Watercare said at the time the upgrade was planned "we'd only observed one occasion in 2019 where levels of PFAS were above the interim guidance value".

It had no shortlisted options or costings for dealing with the PFAS.

In Onehunga, testing had been going on for four years, and most samples were well below the new limit of PFAS in drinking water that kicks in on 14 November, Watercare said.

Incoming new drinking water limits sparked the shutdown. Photo: 123rf

"A person would have to be drinking water with levels of PFAS consistently above the threshold in the new drinking water standards over a long period of time for there to be cause for concern," it said on its website.

The incoming new drinking water limits spurred the shutdown, it said.

It knew in June what the limit would be, and investigated its options, before last month shutting Onehunga down.

Auckland Council today received test results of the PFAS contamination at Onehunga.

The council was sampling from nearby stormwater outlets to figure out if contamination was ongoing.

"We have only received the results today and they will first need to be analysed and assessed against permitted," the council told RNZ.

"This is highly likely to be inconclusive, with the majority of the tests undertaken by Watercare showing very low levels.

"The likelihood of an ongoing discharge is low as the Watercare monitoring record shows very infrequent elevated readings, and because PFOS and PFOA products are effectively banned from importation or use in New Zealand.

It was highly unlikely a single cause would be established.

The ban a decade ago was widely ignored, till the alarm went up behind the scenes at the Defence Force in mid-2017, and six months later for the public.

Contamination from firefighting foam is common.

The council said it was not aware of any firefighting training at Onehunga or Ellerslie fire stations, or by the Defence Force locally. The sites Fire and Emergency investigated were elsewhere.

Watercare said its $2m upgrade last year was not focused on treatment processes.

"We upgraded the treatment plant to increase its capacity," it said.

Prior to the new limits set by the regulator Taumata Arowai, New Zealand relied on guidelines for PFAS maximums based on what Australia has.

Watercare said it did not know how long Onehunga would be shut, but it would probably be out for more than a year.

"We're acting with an abundance of caution."

Treating PFAS has been very difficult and costly, and many cities overseas are struggling with what to do, especially those around defence bases in the US, but scientists recently have made progress.

The Onehunga aquifer was very shallow and extended below old industrial areas.

Other hotspots of contamination by PFAS in Auckland were Devonport and Whenuapai, caused by the Defence Force bases there.

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