Oxygen in Pike River tunnel didn't get in through mine entrance
Friday, 3 May 2019
The Pike River mine recovery team has ruled out one possible source of the oxygen that has delayed plans to en-enter the mine.
It had been intended to go back in on Friday but the re-entry was temporarily suspended earlier in the week after oxygen levels were detected in the mine during testing.
A 3 per cent oxygen level was detected on Wednesday at a borehole directly above a roof fall 2.3km up the tunnel entrance to the mine.
Twenty-nine men died in the West Coast mine during a series of explosion on November 19, 2010. It is hoped re-entry could provide clues as to what caused the explosion.
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On Friday, Pike River Recovery Agency chief operating officer Dinghy Pattinson told Breakfast the team working on re-entry would be going through a process of elimination during the next few days, to determine where the oxygen cames from and what could be done about it.
'It might be something quite simple, but we just have to go through that process to determine that,' he said.
'We've eliminated one thing already, and that is that the oxygen hasn't come from the entrance of the mine and worked its way up to the end of the tunnel.
'And we know that because we put a new drill hole down just after Christmas halfway down the tunnel, and that has remained in nitrogen. So there's no oxygen coming through there,' Pattinson said.
'So the next thing is we are checking the sampling lines.'
The gas monitoring tubes run 4.5km through the bush and down a borehole, On Thursday Pattinson said that a wee nick in a tube would draw oxygen into the tube. 'It could be simple as that but we don't know,' he said.
If there was a nick it could have been caused by a wild animal gnawing on the line.
On Breakfast, Pattinson would not put a date on when the mine might be re-entered.
'You start putting dates on things this early in the piece, and all that does is put everybody under pressure,' he said.
'We're just going to work through the process, and when it is, it will be when it is.'
On Thursday, Pattinson had said resuming the re-entry 'may be as early as next week', depending on the cause of the oxygen reading.
The recovery agency was consulting overseas experts and they hoped to have a better idea in the next week about when they would resume the re-entry. He called the delay a 'hiccup'.
Whether it would be days or weeks away was, at this stage, 'pure speculation'.