Cracks around the slimline hole are undermining efforts to control the atmosphere underground but work to seal them cannot begin as gas levels are too unstable, according to a New Zealand Police spokesperson.

She told ILN that the GAG unit was being rested and would be turned on again “at some stage”

While it was started up again early Sunday morning after receiving maintenance, the intertisation unit has been running “periodically to extend its life span as long as possible”

The spokesperson believes it ran for around 12 hours on Sunday.

Queensland Mines Rescue Service state manager Wayne Hartley previously told ILN the GAG was running for an average of 20 hours per day.

He was particularly concerned about how the turbine was coping with the extended period of deployment.

Hartley said there were natural concerns about the life of the jet engine as it had been going for more than 600 hours.

“Jet engines run far in excess of that but there are safety margins,” he said last week.

Sealing the mine from the surface

Xstrata Coal quickly extinguished the recent fire at its Blakefield South operation after it sealed up the mine and started pumping nitrogen underground.

Yet a decision to seal the Pike River mine from the surface will not be made by teams at the minesite.

The NZ Police spokesperson told ILN that sealing the mine was certainly discussed, “right from the start”

“But the decision-makers around that sort of thing aren’t here in Greymouth,” she said.

“That [decision] would be made at a much higher level.”

The GAG unit first fired up at the site on December 1 and crews have worked throughout the Christmas and New Year’s Day holidays.