Assessment of contamination at Tiwai Point
Our assessment of NZAS’s site report
NZAS provided Environment Southland with a Detailed Site Investigation (DSI) report prepared by its consultants GHD, in August 2021. The DSI report provides information about the contaminants found at the aluminium smelter site on Tiwai Point and is helpful in informing Environment Southland’s work.
Environment Southland engaged EHS Support, an environmental consulting company with international experience in smelter closures, to review NZAS’s DSI report and provide ongoing technical advice to the council.
The EHS Support assessment of the report found many data and information gaps in the DSI report, including that it didn’t address the wider site. EHS Support recommended further investigation.
EHS Support’s key findings of NZAS’s report include:
- Surface soil concentrations of PAHs (polycyclic aromatic hydrocarbon) and fluoride above health risk criteria and ecological screening criteria
- Fluoride recorded at 8-16% concentration in surface soil in select areas
- Groundwater contaminated with “elevated levels” of fluoride, aluminium, arsenic, PAHs (hydrocarbons), and cyanide
- Stormwater 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, but there was not enough information available to establish if the contamination was impacting on the surrounding terrestrial and marine environment.
- Indications contaminants from storage and other infrastructure may be escaping into the surrounding environment. More information was needed about the current landfill, the storage area for spent cell liners (SCL) waste containing cyanide and toxic levels of fluoride, measurements of contamination blown or washed from the facility to surrounding land and water, and historic onsite measurements.
- A lot of data necessary for a full assessment of historic and current contamination across the smelter complex was missing, including exclusion of the landfill, SCL pad and wider receiving environment.
The data from NZAS is only a preliminary snapshot of the recent state of the site, the nature of the receiving environment, and some detail on contamination levels and was not considered a Detailed Site Investigation report by EHS.
See the full EHS Support Assessment here.
Media release: Tiwai Point: Assessment shows significant contamination #1
Media release: Tiwai Point: Assessment shows significant contamination #2