Results of the independent monitoring undertaken earlier this year at Tiwai Point, to fill gaps Environment Southland identified in New Zealand Aluminium Smelters’ data, confirmed its initial understanding of numerous legacy and ongoing sources of contamination to the environment.

The regional council wants the site to be managed as a whole to meet contemporary expectations of industrial environmental performance.

Last week, the smelter company released its own data showing it posed low or no risk to people and sea life, according to a new study commissioned by the plant’s majority owner, Rio Tinto.

At that time, Environment Southland, which monitors the land and sea around the smelter, said it had reached different conclusions to Rio Tinto about the impact of the smelter’s activities on the surrounding coastal marine area at Tiwai Point, near Bluff.

On Wednesday, regional council chief executive Wilma Falconer said a comprehensive regulatory approach would give certainty to both NZAS and Southlanders.

“A whole-of-site regulatory approach would give NZAS and the community certainty for the future operation of the smelter. It would require appropriate environmental standards to be met, the remediation of current contamination and ensure the site is cleaned up when NZAS eventually closes,’’ she said.

Currently, NZAS operates under eight consents, most of which are coming up to 20 years old.

“We want to work with NZAS to speed up this process to provide certainty for its operation and to ensure the smelter is managed in a way that doesn’t leave Southland with a contaminated site and the costs to remediate it.”

The independent monitoring was undertaken by EHS Support (EHS), experts with international experience in decommissioning smelters. The monitoring focused on the coastal marine area around the smelter, landfill and wider site.

The EHS report confirmed manufacturing processes on the site produced waste with contaminants that escaped into the surrounding environment via stormwater drainage and groundwater. Some contaminants were found at levels above the Ecological Screening Values deemed relevant and applicable to the Tiwai Point site, including fluoride, aluminium, zinc, nickel, and PAHs (polycyclic aromatic hydrocarbons).

It said NZAS conducted similar monitoring, and the data and expert conclusions were broadly similar.

However, EHS captured additional samples during a large ‘first flush’ event on February 2, 2023 when, after a dry period, heavy rain washed contaminants into site drainage and then into the sea. This led to the formation of a fluoride and aluminium plume extending well beyond the consented drain water mixing zone. Fluoride and aluminium contamination had the potential to impact marine life.

Fluoride in drain water discharging to the sea during this event was approximately 15 times higher than the Ecological Screening Values, and aluminium in the water was 440 times higher at a point 50 metres beyond the consented drain water mixing zone.

In response, NZAS external affairs director Simon King said: “NZAS is committed to improving our environmental footprint and mitigating the impacts of the smelter, and we will continue to work with our partners, including Ng?i Tahu and Environment Southland (ES) to do so.

”We are pleased that the ES report confirms the findings in the extensive study by GHD, which we shared with ES and released last week’’.

That study found there was a very low probability of any negative health impacts from eating kaimoana taken from the coastal marine area, along with a low risk to marine ecology and no increased risk of health effects for people in contact with sediment and surface water.

“We acknowledge that the ES report found some areas of contamination and concern, and we will be reviewing the ES report together with the GHD report to understand the results, findings, the impacts and what action we need to take,’’ he said.

“The remediation working group – made up of representatives of Ng?i Tahu and NZAS – is focused on ensuring the ongoing best practice efforts to remediate the Tiwai site, including the coastal marine environment, and reports like these help confirm focus area for this important work.”

*Original full-text article online at: https://www.stuff.co.nz/environment/133297137/environment-southland-wants-change-to-tiwai-point-environmental-management

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