Monitoring our impact

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Global environmental and sustainability consultancy GHD was commissioned to undertake an extensive environmental monitoring report on the impact of operations in the coastal marine area around Tiwai.

The research has found a limited risk to marine ecology and no increased risk of health effects for people who come into contact with sediment and surface water or consume kai moana (sea food) in the surrounding coastal marine area.

Environmental Performance

NZAS reports monthly, quarterly and annually to Environment Southland on its environmental performance within consents issued by Environment Southland for discharges to air, land and water.

Closure Study Data - Planning and Results

NZAS engaged international environmental consulting firm GHD to assess any potential contamination of soil and groundwater across the site.

In April 2021, we released the sampling plan that details the areas where GHD determined we should do extra testing as part of the Closure Study, and why those areas were selected.

NZAS Sampling and Analysis Quality Plan Summary

In April 2022, we released our Preliminary Closure Study. This document outlines the key work programmes that will be undertaken to remediate the Tiwai Point site as part of any future closure.

Infographic - April 2022 Remediation Update


Greenhouse Gas and Energy

NZAS’ greenhouse gas (GHG) emissions are reported to the New Zealand Environmental Protection Agency (NZEPA) and are calculated using an agreed methodology approved by the Intergovernmental Panel on Climate Change. The methodology calculates the tonnes of carbon dioxide equivalents (CO2-e) produced by the smelter from the consumption of fuels such as diesel, liquid petroleum gas and fuel oil, carbon anodes, electrical energy use and the generation of perfluorocarbon (PFC) gases.

Tiwai has one of the lowest aluminium smelting carbon footprints in the world generating 85% less CO2-e than the industry average.

We have already reduced direct onsite emissions by nearly 60% since 1990 and is focused on sharing New Zealand’s vision of Net Zero by 2050.

The total calculated carbon dioxide equivalent discharge from NZAS during the year ending 31 December 2022 was 1.99t CO2-e per tonne of aluminium produced.

Environmental Monitoring

NZAS conducts extensive environmental monitoring at Tiwai Point. As part of our commitment to transparency we have released the results of recent monitoring, including assessments of the groundwater surrounding the landfill site and Spent Cell Lining (SCL) storage facilities.

Based on the review work done and the interaction with regulators to date, we are confident we're currently compliant with all of our consents and environmental obligations.

2020 – SCL Groundwater Status

2021 – NZAS Groundwater Monitoring Programme

NZAS has also publicly released 25 years of environmental monitoring reports that detail the results of this monitoring.

Monitoring of Coastal Erosion

We continuously monitor the erosion of the coast around our site and annually report the results to Environment Southland and the Department of Conservation.

We also undertake Pest Animal and Plant Control activity.

2019-20 Annual DOC Compliance Report for PAC

Waste Management

NZAS continues to expand its extensive waste recycling programme to manage its waste in a manner that, where possible, avoids disposal in landfill.

This strategy aims to reduce generation and take advantage of reuse, recycling and energy recovery opportunities.

In May 2022, we stopped putting any new waste in our onsite landfill. We’ve partnered with Waste Management NZ to manage waste on site. All waste metal, paper, plastics, and cardboard are sorted separately and sent off-site to approved organisations for recycling.

We’ve also partnered with Ngāi Tahu to explore site remediation, and this process includes looking at options for the existing landfill.

Waste Management

Waste timber is stockpiled in the landfill for annual chipping before being used to fuel a kiln.

During 2020, independent company Inalco processed all dross as it was produced and began processing Ouvea Premix, which had been stored at Matuara Paper Mill.

The long-term plan is for Inalco to process all Ouvea Premix and the landfilled Metal Reclamation Plant (MRP) stockpile.

Since 2020, Spent Cell Lining (SCL) generated and some stored within existing dedicated buildings has been shipped overseas for processing.



NZAS is committed to preserving the biodiversity on the peninsula and continues to work with the Department of Conservation on the ongoing management of the area.

Work is underway on a biodiversity management plan. Details will be released once the plan has been completed.

Species of significance located within the proximity of the smelter include:

  • Asaphodes frivola moth
  • New Zealand iris
  • Euphorbia glauca
  • Black fronted tern
  • Southern New Zealand dotterel
  • Australasian bittern

The Department of Conservation undertakes monthly checking of traps for stoats, weasels, ferrets and other pests on the peninsula.