No clean up deal in place between Rio Tinto and the Government

Friday, 26 March 2021

What waste is being stored at Tiwai Point?

The reason Environment Minister David Parker is hot under the collar over the clean-up of the smelter site at Tiwai Point is because he’s confirmed there are no agreements are in place between the aluminium producer and the Government.

Parker has been outspoken in the past six months of wanting to know what the state of Rio Tinto’s Tiwai Point site, and what it will take to clean it up.

The issue of how environmentally “toxic” the Tiwai site is was raised when Rio Tinto first said it would close the Southland smelter in August 2021, and the Government took an interest in how the site would be remediated.

In January, Rio Tinto announced it would stay open until December 2024, and then it intends to exit Southland.

* NZAS looks to export toxic waste stockpiled at Tiwai Point

* Environment Minister wants answers about Tiwai site

* Tiwai aluminium smelter to stay open until end of 2024

This week, Stuff asked Parker what agreements were in place for the remediation of the Tiwai Point site, and he replied: None.

New Zealand Aluminium Smelter (NZAS) Tiwai Point Smelter chief executive Stewart Hamilton

“Until the Government is provided with the information it needs, including physical sampling and testing of soils and groundwater, we do not have an objective and evidence-based understanding of the actual state of the site at Tiwai Point,” Parker said.

The Government is now waiting on Rio Tinto to provide a preliminary closure study but that is not expected to be completed until 2023.

In February Ministry for the Environment chief executive and Secretary for the Environment Vicky Robertson told the Environment Select Committee that the legal liability for Rio Tinto to remediate the site once the smelter closed had been ‘’difficult to pin down”.

Parker said the Government needed to know the level of any contamination in order to understand what remediation was required.

“…that includes any pollution to the land under the potlines and to the groundwater. We don’t have that information. That is why the Government has provided funding of $300,000 to Environment Southland to undertake an investigation,” Parker said.

It turns out that Rio Tinto also has no idea of what’s under the potline buildings.

New Zealand Aluminium Smelter chief executive Stewart Hamilton said it remained committed to closing the site in a responsible manner.

“We are absolutely committed to responsible closure leaving a positive legacy for the community of Southland,'’ he said.

”We will continue working collaboratively with the New Zealand Government, our local community and Ngāi Tahu as mana whenua as we go through our closure study process and continue running a safe and stable operation producing some of the lowest carbon aluminium in the world.”

The closure study would take the issues of the potline and groundwater into account, Hamilton said.

“Is there contamination under the potlines? We don’t believe so, but we don’t know for sure so that will be taken into account as part of the closure study,” Hamilton said.

NZAS had employed external independent experts to assist with the closure study, and in the last two months 238 bores had been drilled and samples taken, which were being analysed.

NZAS says it has not dumped asbestos in its landfill since the 2000's. There is also cleanfill concrete and refactory bricks in the landfill.

The closure study would also take into account that another industry, such as green hydrogen, may want to use the site, and the socio-economic impacts of the closure on the community, he said.

NZAS has set aside $298m as a provision in its accounts for the closure and rehabilitation of its Tiwai site.

What is the environmental impact?

NZAS operates under eight consents issued by Environment Southland that allow it to discharge water into the coastal marine area of Bluff Harbour, discharge treated effluent to Foveaux Strait, discharge contaminants to the NZAS landfill, to discharge storm water and process water to land in circumstances where it may enter water, take and use groundwater for industrial supply, to occupy the foreshore and seabed with an untreated effluent discharge pipe and diffuser, and to discharge treated sewerage to land.

Environment Southland visits four times a year to audit and monitor the sampling that NZAS has completed.

Spent cell liner (SCL) material is stored on a purpose built concrete pad, which has a special drainage system to capture and treat any run-off. It is about 100m from a beach.

In a 2019/20 compliance report, there was one breach of the smelter’s consents, when the cyanide limit for the effluent discharge to Foveaux Strait was exceeded on one occasion by a margin of 10 per cent.

The breach occurred due to a change in process by the smelter and was judged to have a low level of environmental impact.

In the past five years only one infringement notice has been issued. In April 2020 there was a small discharge of cathode lining leachate to ground. This was due to human error and NZAS self-reported the incident.

What waste is at the site?

This week, Stuff went to Tiwai Point to see the site – including the areas of concern highlighted in the Treasury commission Aurecon report that was done to assist the Government in its negotiations with the company.

That report provided a high level overview of the likely hazards and risks at the site and potential for contamination.

Spent cell liner (SCL) material is kept in a large shed onsite. The shed is monitored for any leaks into the groundwater.

The biggest issues relate to where spent cell liner (SCL) is stored, and what's in the smelter's own landfill.

SCL is made up of carbon refactory bricks, which are used in the aluminum-making process for five to six years. They contain flourides, cyanides and nitrides.

Every year the smelter produces about 6000 tonnes of SCL, and at the moment it exports about the same amount. Around 58,000 tonnes has been exported during the past decade.

There is 181,000 tonnes of SCL stockpiled at Tiwai, and the smelter says it is actively looking for a way to export it.

Between 1971 and 1992 the smelter stored all SCL on a purpose-built concrete pad, which has a special drainage system to capture and treat any run-off.

The pad, which looks like a large mound, holds 106,000 tonnes of SCL and is covered with pebbles and vegetation. It is located in sand dunes about one kilometre from the production site, and about 100m from the beach.

Run-off is held in storage tanks and exposed to the sun, which reduces the cyanide content of the runoff to the level specified in a consent.

It is then pumped out a 200m outfall pipe off the beach and dispersed with the tide, when it is flowing away from Bluff, and the outfall is inspected annually.

The cyanide content is set at 20g/m3 to ensure that during the course of a year there is no adverse effect on the coastal marine area.

Groundwater monitors at the building where spent cell liner is stored at Tiwai Point.

Groundwater is monitored by 16 bores around the site to ensure there is no leaching into the soil.

Erosion at the beach was monitored and, like any other beach, it eroded and then replenished, Hamilton said.

To the best of Hamilton’s knowledge, there had been no issues with contaminated groundwater at the pad site.

Carbon that is unable to be used in the production of new anodes in the NZAS landfill at Tiwai Point.

After 1992 the company started storing SCL, which looks like dusty grey rubble, in large, purpose-built sheds on-site.

“It’s far easier to store it in a building, we’re able to move it around and manage it easier,’’ Hamilton said.

In 1995 a storage building floor cracked in and contaminants including cyanide, fluoride and ammonia had had to be pumped out.

A NZAS spokesperson told Stuff that the cathode storage building was purpose built with layers of sand and impermeable membranes beneath a concrete floor.

Cyanide and fluoride levels were contained within the building foundations.

“In short the building did exactly what it was designed to do,'’ the spokesperson said.

NZAS is also consented to operate a 12 hectare landfill, that is also close to a beach, although at the time Stuff visited the site being used was much smaller.

It contains stockpiles of carbon, which is unable to be used in the production of new anodes, man-made mineral fibres such as glass wool which is double bagged, asbestos, clean fill of concrete and construction and refactory bricks.

NZAS says it has not dumped asbestos in the landfill since the 2000s.

The landfill also contains one “cell” of historic dross that is due to be removed this year, and a cell of Haysom's dross.

There are 19 groundwater bores around the landfill which are used for monitoring groundwater for a range of substances at various frequencies and depths.

The samples are routinely analysed and some, but not all, results are reviewed by ES.

About 620,000 cubic metres of waste had been buried at the landfill since the smelter started in 1971, and part of the exit plan is to decide what to do with that material.

Why won’t Parker visit the Tiwai site?

Hamilton said NZAS has invited Parker to the site several times since the closure was announced.

“We were unable to accommodate an initial request for officials to visit site in December 2020, however since then we have hosted Environment Southland, Worksafe, Invercargill City Council and sent individual invitations to officials at the Ministry for the Environment, Ministry of Business, Innovation and Employment and Treasury.

“We have also asked officials to please pass those invitations to their ministers. We certainly understand and respect the interest our stakeholders have in how we operate, and how we will close responsibly. Visiting and understanding our operation is an important part of that.”

Parker said officials involved in negotiations have consistently asked Rio Tinto to have access to the site to have a better understanding of its condition and remediation requirements.

“These requests have been consistently denied by Rio Tinto for a range of stated reasons; firstly to not impact staff morale prior to the deal with Meridian being secured and subsequently for health and safety reasons.

“I have been on the smelter site quite a few times. We know there are landfills and potlines there. Another visit will not reveal the level of pollution to the land and water mentioned above.'’