Environmental Performance

Tiwai Pointer

NZAS has several Resource Management Act 1991 consents issued by Environment Southland for discharges to air, land and water.  NZAS reports monthly, quarterly and annually to Environment Southland on its environmental performance within these consents.

In 2020 during the Covid-19 lockdown NZAS received one infringment notice for a spill to ground at the Treated Effluent Plant.  No other penalties for failure to comply with applicable law were received.


Closure study data - planning and results

NZAS has engaged GHD, an international environmental consulting firm, to conduct an assessment of any potential contamination of soil and groundwater across the site.

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

In October 2021, NZAS released the Detailed Site Investigation report developed by GHD.

In April 2022, NZAS released its 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. 


Greenhouse Gas and Energy

NZAS’ greenhouse gas (GHG) emissions are reported to the New Zealand Environmental Protection Agency 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.

The total calculated carbon dioxide equivalent discharge from NZAS during the year ending 31 December 2021 was 1.99 t CO2-e / per tonne of aluminium produced.  In the year ending 31 December 2021 the average energy use was 71 GJ 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, NZAS is confident it is currently compliant with all of its consents and environmental obligations.

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

NZAS IDC Report - 1995 NZAS IDC Report - 2009
NZAS IDC Report - 1997 NZAS IDC Report - 2010
NZAS IDC Report - 1998 NZAS IDC Report - 2011
NZAS IDC Report - 1999 NZAS IDC Report - 2012
NZAS IDC Report - 2000 NZAS IDC Report - 2013
NZAS IDC Report - 2001 NZAS IDC Report - 2014
NZAS IDC Report - 2002 NZAS IDC Report - 2015
NZAS IDC Report - 2003 NZAS IDC Report - 2016
NZAS IDC Report - 2004 NZAS IDC Report - 2017
NZAS IDC Report - 2005 NZAS IDC Report - 2018
NZAS IDC Report - 2006 NZAS IDC Report - 2019
NZAS IDC Report - 2007 NZAS IDC Report - 2020
NZAS IDC Report - 2008  


Monitoring of Coastal Erosion

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


Spills to the Environment

One significant environmental spill occurred in April 2020 during Covid-19 lockdown when pipes burst at the Treated Effluent Plant resulted in a spill to ground.  The incident was investigated and reported to Environment Southland.  An infringement notice was issued for this environmental incident.


Waste Management

NZAS continued its extensive waste recycling programme during 2020 to manage its waste in a manner that avoids, where possible, disposal in landfill.  This strategy aims to reduce generation and take advantage of reuse, recycling and energy recovery opportunities.

All waste metal, paper, plastics, and cardboard are sorted separately and sent off-site to approved organisations for recycling.  During 2020 approximately 2,500 tonnes of these materials were sent for reprocessing.

During 2020 general waste, carbon material, and clean fill was deposited in separate storage cells at the NZAS landfill.  Cells at the landfill are managed to minimise exposed open faces and are progressively covered with gravel and/or wood chips to minimise dust.

This material deposited at the NZAS Landfill in 2020 comprised:

  • General Waste - 821m3
  • Clean Waste - 537m3
  • Carbon Material - 3,513m3

Waste timber is stockpiled in the landfill for annual chipping to be used as ground cover material on the carbon pile.   An additional 100 tonnes of non-hazardous waste was deposited at the Invercargill City municipal landfill.  During 2020 independent company Inalco processed all dross as it was produced and commenced 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.  During 2020 Spent Cell Lining (SCL) generated and some stored within existing dedicated buildings was shipped overseas for processing.



NZAS is committed to preserving the biodiversity on Tiwai Peninsula.  NZAS continued to work with the New Zealand Department of Conservation for ongoing management of the Tiwai Peninsula.

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

  • Asaphodes frivola moth
  • NZ iris
  • Euphorbia glauca (by Tiwai Wharf)
  • Black fronted tern
  • Southern NZ dotterel
  • Australasian bitten.

During 2020 NZAS took no specific actions for biodiversity sustainability programmes apart from general pest control on the Tiwai Peninsula.  The New Zealand Department of Conservation continued monthly checking of traps for stoats, weasels, ferrets and other pests on Tiwai Peninsula.