A recent study commissioned by New Zealand Aluminium Smelter (NZAS) indicates that the waters surrounding the Tiwai Point aluminium smelter pose minimal or no threat to both human health and marine life. NZAS is owned by Rio Tinto (80 per cent) and Sumitomo Chemical Company of Japan (20 per cent).
In a statement released, NZAS reported that extensive testing conducted by consultants GHD aimed to supplement the detailed site investigation carried out in 2021, establishing baseline indicators for the smelter site.
The study aimed to assess the potential adverse effects of smelter discharges on the coastal marine environment and the well-being of individuals engaging in recreational activities and food gathering in the area. According to the report, there is no heightened risk of health effects for people coming into contact with sediment, surface water, or consuming seafood within the coastal marine region.
The findings acknowledge a limited risk to marine ecology associated with discharges from the landfill. Although localized effects on aquatic organisms are conceivable, elevated copper concentrations near the landfill are deemed unlikely to have a measurable long-term impact. Notably, elevated copper levels were detected in water samples from various locations around Bluff Harbour, including those distant from the NZAS smelter, suggesting secondary sources.
The primary pathways for contaminant transport toward the coastal marine area were identified as three drains. While adverse effects on aquatic organisms were plausible near the north drain discharge point, once the discharge reached the coastal marine area beyond the drain water mixing zone, the risk of measurable adverse long-term effects on aquatic organisms was deemed low.
The GHD studies conducted since 2021 align with findings from 1995 and 2006, indicating that discharges from NZAS drains have a limited impact on marine species within the coastal area. NZAS Chief Executive Chris Blenkiron expressed satisfaction with the report's findings, asserting that they instil confidence in the effectiveness of the company's actions to mitigate the smelter's environmental impact.
But it also offers clarity on areas where we can strive for improvement," he stated. "Tiwai has a history of over 50 years, and we recognize that our practices haven't consistently met expectations. However, we've diligently endeavoured to enhance our environmental performance, and this report validates that we are on the right path."
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