New Zealand Aluminium Smelters
The remediation of the New Zealand Aluminium Smelters (NZAS) Tiwai site is a high priority for Southland.
In December 2020, David Parker, Minister for the Environment, asked Environment Southland to investigate NZAS’ Tiwai site, amid the Government’s concerns about remediation of the site.
Due to the Minister’s request and following the announcement of the smelter’s closure, Environment Southland increased the monitoring of NZAS' existing consent conditions, which include discharges to air, land, groundwater and coastal waters, and engaged external consultants to provide advice on further investigations.
Environment Southland is implementing a monitoring plan for the NZAS smelter to help the Government understand what is required for remediation of the site. This builds on our existing compliance monitoring programme, which has been in place for many years. The compliance programme is to ensure NZAS is meeting its consent conditions, and requires the company to take its own samples and supply the results to us quarterly and annually. Environment Southland audits NZAS’ results annually.
The Government has made $300,000 available to Environment Southland to support the monitoring programme. The funding has enabled the council to engage Aurecon, an engineering design and advisory company, to provide technical advice on the monitoring programme. This includes recommendations for further monitoring, as required, and also the management of land contamination at aluminium smelters. The work by Aurecon is expected to be complete by the end of April.
The information provided by Aurecon will give the council a clearer view of ongoing investigations required to get a deeper and broader understanding of the site, to help inform the Government about what is required for remediation. The council will be reporting to the Government regularly.
Environment Southland is not responsible for the transport or storage of hazardous substances. However, the council has been in discussions with Invercargill City (who does have responsibilities in these areas) about how best they can be managed. This is in recognition of Environment Southland’s expertise in monitoring hazardous materials.
The following information is an overview of the management of the smelter.
Environment Southland will share as much information as possible with the public, providing it does not affect our regulatory role as a regional council. The scope for monitoring and investigating contamination on the site was within regulatory requirements.
The council must be able to gather data through acceptable best practice to provide assurance that it is technically robust and accurate. The council is maintaining a strong regulatory oversight, which means everything must be done correctly and under the right legal framework.
How does Environment Southland monitor consents?
Currently, Environment Southland investigates complaints and self-reported incidents, and assesses compliance against the conditions listed in six of NZAS’ discharge consents that require inspecting. Each of the consents have different conditions that need to be adhered to – this includes providing sampling results for different contaminants at varying frequencies. We visit the site four times a year to audit the sampling and monitoring that NZAS has completed.
Environment Southland will also be carrying out air, land, coastal water and groundwater sampling at the site. We are monitoring for NZAS’ consent conditions and also the effects of permitted activities under the proposed Southland Water and Land Plan. We’ll also be assessing contamination across the site.
New Zealand Aluminium Smelters Limited (NZAS) holds six discharge and water take consents that require inspecting. The consents are:
- the discharge of contaminants to land where they may enter coastal water;
- the discharge of treated sewage to land;
- the discharge of treated effluent to the Coastal Marine Area (CMA);
- the discharge of water including contaminants to the CMA;
- the discharge of contaminants to air from the aluminium smelter and related activities;
- to take and use groundwater for industrial supply.
Environment Southland monitors, investigates complaints, self-reported incidents and assesses compliance against the conditions listed in NZAS’ discharge consents that require inspecting.
Monitoring is conducted by the following methods:
- Site visits – to assess compliance at a moment in time against consent conditions and rules.
- Desk top audit – based on data provided by the consent holder.
- Reactive – incident response.
Environment Southland’s role as a regional council is to manage the discharge of contaminants to air, land, coast and water. We do not control the transportation or storage of hazardous substances.
The monitoring is expected to be expanded beyond consent requirements so that we can have a clear understanding the condition of the site and advise the Government.
When the landfill current consent application was granted in 2003, it was in accordance with the rules and regulations at the time, using the information available.
Environment Southland is working with Aurecon at present to better understand the potential impact of the smelter’s activities on the site, and to develop a plan of action. This includes the landfill site. Considering the impacts of climate change is also part of the overall monitoring strategy.
The landfill pre-dates the RMA. It existed before the consent was granted in 2003, and before the previous consent was granted in 1995. The current landfill consent is due for renewal in 2023 and will be subject to landfill rules under the proposed Southland Water and Land Plan and the RMA.
Environment Southland regularly visits the NZAS site and conversations about the risk of coastal erosion on the site have been had with NZAS’ environmental team.
Environment Southland will continue to assess monitoring reports provided by NZAS, which includes biannual groundwater sampling and reporting of additions to the landfill. Since the announcement of the closure, we have also:
- Undertaken an inspection of the landfill
- Investigated other bores that could be sampled in close proximity to the landfill
- We will undertake our own sampling from these bores or request the monitoring results from NZAS
Our further investigation work will be based on latest information available to us.
Spent cathode liners
Spent cathode liners, also known as Spent Cell Liners or SCL, is a solid waste produced during the manufacture of aluminium metal.
NZAS has a consent (203379) to ensure that leachate, rainwater and storm water is captured from the area of the stockpile and is treated. Once the treatment process is completed it is discharged to Foveaux Strait.
Monitoring in 1991 showed that contaminants into receiving water exceeded the consent limits in the consent conditions.
Groundwater was monitored at the site from 1992 onwards, and independent consultants employed by both Southland Regional Council and NZAS provided recommendations on remediation actions.
In 1995, Southland Regional Council advised NZAS that the “cathode pad contaminant plume be allowed to continue to recover by natural dispersion alone”.
Groundwater monitoring continued for the next 10 years, and showed signs of declining levels of contaminants. In 2006, Southland Regional Council wrote to NZAS: “… contaminants below the SCL site are declining due to both dilution and transport to the CMA. There is no evidence that transport and discharge to the CMA through groundwater is having any immeasurable impact on the environment.
“As a consequence of the report, Council have concluded that there is no further requirement to undertake monitoring of the SCL groundwater contamination, unless the SCL storage areas is unsealed and opened to the public.”
The consent conditions require the consent holder to take water samples every time there is a discharge. The results of these are reported to Environment Southland quarterly. Annual samples are taken of the receiving water, and the results are reported annually.