The Paritutu plant in New Plymouth. Photo: CC / Phillip Capper
A dioxin researcher and community advocate says a close eye will need to be kept on global chemicals company Dow's promise to clean up a controversial plant in New Plymouth.
Corteva Agriscience, previously the agricultural arm of Dow DuPont, this week transferred ownership of its Paritutu plant to Dow.
From the 1960s through to 1987, Ivon Watkins (later Ivon Watkins-Dow) made the herbicide 2,4,5-T in New Plymouth - which contained the toxic dioxin TCDD.
The herbicide was a key component of Agent Orange - the defoliant used by the United States military in the Vietnam War - and has been linked to cancers and birth defects.
Corteva is demolishing the New Plymouth plant and in July made a commitment to thoroughly test and clean up the site - a commitment Dow said it will uphold.
Researcher and advocate Andrew Gibbs cautiously welcomed Dow's involvement back at Paritutu.
"Well I think Dow are responsible. They ran the site primarily and have the resources to put it right. The important thing is that there is strong independent oversight."
Gibbs said the company's commitment should be applauded but a close eye would need to be kept on them.
He was particularly concerned about a number of areas on the Paritutu site.
"I think a key issue will be under some of the sites that have been sealed up and concreted over and over where the drums were lying around over at the back of the site."
Gibbs said only when any test results were independently verified would the true level of contamination be known.
New Plymouth Mayor Neil Holdom was adamant the site was contaminated.
"I'm absolutely convinced there's a large amount of toxic material in the ground there. I'm absolutely sure of it and when the testing is done we'll know.
"If what I am led to believe is correct this is going to be a multi-million dollar remediation project because the historical evidence indicates there's widespread, deep and really challenging toxic material in there."
Holdom believed the decision to transfer ownership to Dow formed part of the contractual obligations it always had to clean up the site.
He would be meeting Dow on Monday.
"I'm looking forward to hearing how we can resolve this thing permanently and to a really high standard.
"We've indicated to them that we want some independent oversight and I've been working with Jackie King of Taranaki iwi and I think they are really well positioned as an iwi to determine who's appropriate to be part of that team."
Mayor Neil Holdom wants to hear plans for a high standard of remediation when he meets Dow on Monday. Photo: RNZ / Robin Martin
That team would include the regional council, iwi, the New Plymouth District Council and government agencies, he said.
Holdom said Dow - which had sales of $US55 billion in 2021 - had deep enough pockets to finance any remediation project.
"They are of a scale that this is just a part of their business but we just want to make sure in Taranaki that it is done to the very highest standards because [the plant] is right next to a marine reserve and a suburban area. There are people living in their houses just a few metres away from the edges of this site."
In a joint statement, Dow and Corteva said demolition activity underway on the site was expected to be completed by the end of the year.
Dow would then undertake further sampling and testing and work with regulators to develop a remediation plan based on the test results and compliance with regulatory requirements.
Dow managing director for Australia and New Zealand Karen Dobson said the company was acutely aware of public interest in the Paritutu site.
"Dow will continue to work closely with stakeholders to ensure ongoing environmental stewardship and adherence to all regulatory requirements. We understand that testing and remediation of this site is a priority for the local community and are committed to remediate the site in a safe and sustainable way."
Dobson said future plans for the site would be explored as part of the remediation plan development.
Dow has been operating in New Zealand for more than 60 years and its international portfolio includes plastics, industrial coatings and silicones and a range of science-based products and solutions in markets such as packaging, infrastructure and consumers applications.
Dow operates 104 manufacturing sites in 31 countries and employs about 36,000 people.
Corteva said it remained committed to New Zealand agriculture and would continue to maintain a head office in New Plymouth and a strong employee presence in the city to support customers in New Zealand, Australia and other locations globally.