Tiwai Point: Assessment shows significant contamination #1

Media Release #1

14 September 2022

Tiwai Point: Assessment of NZAS data shows significant contamination at smelter site

A review of a New Zealand Aluminium Smelters (NZAS)-commissioned report has found “numerous legacy and ongoing sources of contamination to the environment” from the Tiwai site. It also identifies a number of areas where more information is needed to assess the impact of that contamination on the surrounding environment.

Environment Southland chief executive, Wilma Falconer: “With any industrial operation of this scale, some level of contamination at the site is to be expected, however, it is evident from the data supplied by NZAS that a significant mass of contamination has been discharged into the environment. What this data doesn’t tell us is whether the historic and current NZAS operations have had, or are causing, negative effects to the land, groundwater and coastal marine environments.”

As part of our work programme to clarify the degree and impact of contamination at Tiwai Point Environment Southland asked EHS Support, a consultancy with international experience in decommissioning smelters, to assess the NZAS-commissioned Detailed Site Investigation report, which provides information about the contaminants found at the smelter’s site.

The EHS Support assessment says the data reveals pollutants in groundwater, drains and soil. EHS Support’s key findings of NZAS’s report include:

• Contamination found at the site:
  • Fluoride recorded at 8-16% concentration in surface soil in select areas
  • Surface soil concentrations of PAHs (polycyclic aromatic hydrocarbon) and fluoride above health risk criteria and ecological screening criteria
  • Groundwater contaminated with “elevated levels” of fluoride, aluminium, arsenic, PAHs (hydrocarbons), and cyanide
  • Storm water drains’ sediment contains “elevated levels” of fluoride, aluminium, PAH, and heavy metals.
• Concentrations above generic or default risk-based criteria, above commercial/industrial and recreational health risk criteria, and ecological screening criteria. However, there was not enough information to establish if the contamination is impacting the surrounding terrestrial and marine environment.
• Indications of contaminants from storage and other infrastructure may be escaping into the surrounding environment.

The data from NZAS is a preliminary snapshot of the recent state of the site, the nature of the receiving environment, and some detail on contamination levels but not a Detailed Site Investigation report of the Tiwai site.

A lot of data necessary for a full assessment of historic and current contamination across the smelter complex was missing from the DSI report, including data relating to the landfill, spent cell liner pad and wider environment.

Wilma Falconer: “The gaps in the data mean we are yet to understand the full extent of contamination at the Tiwai site and the impact on the surrounding environment, including the coastal marine area.

The environment within and surrounding the NZAS facility is somewhat forgiving with a very transmissive, shallow groundwater system underlying the site and a receiving environment that allows for rapid dilution of contamination.

“EHS Support’s assessment has been useful in piecing together, with NZAS, the initial picture of the site’s contamination and we are working collaboratively to more clearly establish the potential impacts to the wider environment, particularly in the coastal marine area and at the landfill site.”

See Media Release 2: Tiwai Point: Action underway to address smelter contamination

For more information and links to relevant documents go to:

www.es.govt.nz/environment/industry/new-zealand-aluminium-smelters