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Parker's tough words follow claims the company reneged on a verbal agreement given last week to remove the waste that has been stored in the Southland town of Mataura for the past six years.
The the 10,000 tonnes of ouvea premix in a disused paper mill came close to being inundated by flood waters last week which could have set off a highly dangerous cloud of ammonia gas.
Rio Tinto's website states it is committed to mitigating its operations' impact and has stories about its efforts to help look after the environment, from bears in Canada to native trees in Australia.
Parker said Rio Tinto needed to clean up its "mess" in Southland.
"For them to try and escape some responsibility for cleaning up the mess that comes from their own smelter. It's outrageous. I can't reconcile it with their statements of corporate responsibility that they put on their own website.
"You know, they talk about preserving grizzly bears in Canada and migrating birds in Australia. Well perhaps they could take the same stance when it comes to the people and the environment of Southland."
Rio Tinto thought it had dealt with the problem when it paid Bahrain's Taha Industries to take the dross off its hands in 2014.
Fast forward to last week, and Gore District Council chief executive Steve Parry said it had a verbal agreement with the chief executive of the smelter, Stewart Hamilton, to speed up the removal of the dross, and and store it at the smelter.
But days later, Parry said, the head of the smelter had reneged on that deal.
Parker said that was disgraceful.
"Central government agreed to kick in a million dollars, the smelter a bit more than a million dollars and the councils some hundreds of thousands of dollars to get the clean-up started in a major way.
"You know, we didn't bring to bear those underlying legal liability issues but, you know, maybe we the Government should be looking at suing them now. I've had enough."
Parry said he was told that Rio Tinto did not want to import any extra liability on the site until its strategic review on the future of the Tiwai Point smelter was completed at the end of March.
The contract in place provides for moving the dross from the factory in up to two-and-a-half years. "Given the floods we've just had that was considered to be just too long." The high-level agreement in principle was for a three-month removal period starting at the end of March, Parry said.
Parry said as a small council, Gore would be reluctant to take legal action on its own.
"What we don't want to see is a process bogged down in legal action which could take a long time and cost a lot of money.
"We need to remember there is a contract in place, it is still running, it's performing to expectations and in two, two-and-a-half years that warehouse in Mataura will be cleared out."
"It's got a history of crying wolf over their financial situation to try to wring out concessions from successive New Zealand Governments," he said.
"They're trying to hide behind a contract they had that went wrong. They paid a company to take this dross from this site and in the end that dross was just dumped at various sites around Southland. It wasn't processed. Rio Tinto say it's not their problem that their contractor didn't do it."
The minister said any court action would not take place quickly, and he didn't want to overstate the risk given the highest flood on record did not get into the warehouse. But there was a contrast between Rio Tinto's statements on the environment and its conduct in New Zealand.
Smelter chief executive Stewart Hamilton did not return RNZ's calls asking for comment. He released a statement which did not address whether the company had given a verbal undertaking.
"We remain committed to a solution that removes the material," the statement reads. "NZAS has committed to contributing $1.75 million to the costs of safely removing and processing the material."
Sort Out The Dross action group spokesperson Cherie Chapman said Rio Tinto should take care of its waste instead of palming off the problem on to the people of Southland.
"The community is very angry, very concerned, very bewildered about why this stuff has not been picked up at speed and taken out of the end of the Mataura paper mill."
Chapman said it was important to remember that nobody in Mataura had a say about the dross being stored in the middle of their town.
"It was snuck in to those buildings without any consents whatsoever, and the resource consent was then retrospective. Shortly after the company went into liquidation. The council has no recourse really when a company goes into liquidation, this is why I think Rio Tinto needs to pick up its act."
Chapman was sending out an open invitation to the smelter to attend a public meeting in Mataura tomorrow night to discuss the problem and what should be done about it.