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Fire and Emergency New Zealand (Fenz) teams are this morning heading to the Mataura paper mill to assess whether the town remains at risk from an ammonia gas reaction.
Thousands of tonnes of a potentially dangerous chemical — known as ouvea premix — is stored in the former Carter Holt Harvey paper mill, next to the flooded Mataura River.
The dross from the New Zealand Aluminium Smelters (NZAS) Tiwai Point smelter is classified as a class 6 hazardous substance, which can generate poisonous ammonia gas if it comes into contact with water.
Emergency Management Southland this morning said Fenz teams were heading to the plant to assess the ouvea premix before any decision is made to allow any residents to return to Mataura.
"This will take the morning to be complete, and following that the town will be assessed for any issues and a further update will be provided then."
Southland Civil Defence Emergency Management group controller Angus McKay confirmed yesterday some water had ‘‘definitely’’ got into the paper mill.
However, he said there was no evidence of ammonia discharge.
‘‘The level [of water ] is right at the base of it but certainly the amount of water flowing down from Mataura at the moment — there will be some water going through there.’’
Mr McKay believed they had done the ‘‘best’’ they could given the situation.
He told the Otago Daily Times extra sandbags had been placed around the building to protect it, but by late yesterday floodwaters were threatening to inundate it.
However, even if a gas reaction occurred, he was confident the cordon already in place in the area would keep people safe from any gas released into the air.
The river itself was also running so high that anything entering the water would be diluted to the point it was unlikely to pose a threat to wildlife, he said.
It was still too early to understand what exactly had happened or if there was any reason to worry about it.
The situation would be assessed as soon as possible, he said.
About 10,000 tonnes of ouvea premix was stored in sacks on stacked pallets inside the old plant.
Australian company Inalco Processing Ltd was last year awarded a contract to remove about 22,000 tonnes of the substance from the paper mill and other sites in Invercargill, but the work was expected to take six years.
In 2018, Gore District Council chief executive Steve Parry said Mataura had come close to environmental disaster during a flash flood earlier that year.
The dross was previously owned by Taha Asia Pacific, which went into liquidation in 2016 and in March 2018 a $4million package to remove the substance was brokered by NZAS, the Government and Southland councils.
The contract ensured the 10,000 tonnes of premix stored near Mataura would be moved first, due to the ‘‘significant risks posed to both the environment and people by having the premix stored next to the Mataura River’’, Mr Parry said at the time.
The reassurances did not wash for some residents, including Sharon Argyle, who has lived in Mataura for 64 years.
She was not happy the council had ‘‘left all that toxic stuff’’ at the paper mill and that the issue had been allowed to rumble on for so long.
‘‘They were pretty slow and now it’s too late.”
Doctors Rd resident David Keaton said even though council staff had advised people to go to higher ground, he did not feel comfortable staying in Mataura due to the toxicity risk.
“We have known about this for so long — and [the] council is not doing anything about it. It’s a time bomb.
“We had everybody at our house since yesterday because it is in a higher area — but we decided to come to Edendale to avoid the toxicity.
‘‘Edendale people have been very kind and offering their support.’’