Former Paritūtū chemical plant in New Plymouth has potential for contamination, investigation finds

The plant in Paritūtū, New Plymouth. Photo / CC / Phillip Capper

By Robin Martin of RNZ

• Investigation of former Dow chemical plant concludes there exists potential for contamination
• Herbicides 2,4,5-T and 2,4-D – containing toxic dioxins – were made in New Plymouth from 1960 through to 1987
• They were key components of Agent Orange which has been linked to birth defects and cancers
• Dow has committed to a remediation project at Paritūtū expected to take several years

A probe into pollution at a former chemical plant in New Plymouth concludes there is potential for contamination to exist that could affect human health and the environment.

Ivon Watkins – later Ivon Watkins-Dow – made the herbicides 2,4,5-T and 2,4-D at Paritūtū from 1960 through to 1987.

The herbicides, which contained toxic dioxins, were a key component of Agent Orange – the defoliant used by the US military in the Vietnam War – which has been linked to cancers and birth defects.

The Paritūtū plant was demolished in 2022, and Dow and its New Zealand-based remediation partner Tonkin & Taylor were involved in a clean-up process expected to take several years.

Tonkin + Taylor was responsible for the just completed Preliminary Site Investigation (PSI).

“It concluded that there is a potential for contamination to exist in surface soils, underlying soils, and groundwater (shallow and deep) which could affect human health, and/or the environment,” Dow said in a statement.

It said the PSI was a significant milestone in the remediation project and would help it understand the history of the Paritūtū plant and the possibility for any contamination.

Dow conceded the investigation “did not involve collecting samples from the site; however, information from the PSI will help to plan future sampling if required”.

The PSI involved a review of:

• Historical documents and data
• Former site activities
• The environmental setting of the site
• The regulatory framework and consenting requirements

Dow said information gathered and interpreted as part of the 137-page PSI would be used to help plan future soil and groundwater investigations and outline possible remediation measures.

“We remain committed to transparency and community engagement throughout this remediation process. The next step involves a Detailed Site Investigation (DSI), which will focus on comprehensive soil and groundwater sampling to better understand current conditions at Paritūtū and whether there are any existing exposure pathways.

“Following the process outlined in the published Remediation Road Map, remediation efforts will then commence where necessary.”

Dow said the Paritūtū PSI was a comprehensive report and had been reviewed and endorsed by an independent peer reviewer (Becca) appointed by Taranaki Regional Council (TRC) and tāngata whenua.

The full Paritūtū PSI Report would be submitted to the TRC.

A four-page summary of the report includes:

• A brief history of the site
• A description of the geology of the site and water movement above and below ground
• An overview of manufacturing operations from the early 1960s until the site ceased operations in early 2021
• A description of the site’s environmental setting, including source(s) of contamination, pathway(s) for exposure, and receptor(s).

Further information can be found on the Tonkin + Taylor project website.

- RNZ