The mission to get back into the Pike River mine is now so advanced a senior police officer has officially joined to examine any evidence they find.
Detective Senior Sergeant Grant Collins is now part of the Pike River Recovery Agency (PRRA) and his appointment is a sign the recovery mission is moving ahead well.
Chief operating officer Dinghy Pattinson described the mine as a "crime scene", and said there was a plan on how it would remove evidence such as machinery from the mine.
- Exclusive: The forgotten note inside Pike River to the deceased
- Bernie Monk and Patrick Gower's emotional journey into Pike River
- Pike River boss: Chance of successful recovery 'higher than 90 pct'
There is also a plan to take the methane out, then put nitrogen in - and then fresh air is underway.
The top of the Pike River Mine is covered in ice. The temperature is freezing, but it hasn't always been that way.
The Pike River vent shaft is a real symbol of the explosion known to all New Zealanders, because of the absolute inferno that erupted out of there and into the sky.
It is a reminder that under this cap, and beyond this wall at the bottom of the mine, is full of methane.
Dinghy Pattinson will lead the mission into the mine - but first he has to stabilise it.
"You've got 95 to 96 percent methane in the underground environment," Mr Pattinson says.
"Everyone is confident it will work - we just have to put it through the risk assessment process."
The recovery operation aims to reclaim the 2.3km access tunnel or drift, where there could be evidence or bodies. The first 30m of the portal is fresh air; beyond its wall is the methane.
With no oxygen, the mine is inert, meaning you can't have a flame. To get rid of that methane, nitrogen will be pumped in at the bottom and the methane forced out the top.
The mine will then be full of nitrogen, which is when it is safe to start pushing fresh air in.
But they are not done with the nitrogen yet; it'll also be pumped back in to keep part of the mine back from what is called the rockfall - inert, so there can't be a fire.
It is a precarious operation, and the wrong mixture of gases could be disastrous
"We don't want fresh air and oxygen getting to the rockfall, because that could cause the previous spontaneous combustion, the previous fire, to reignite," Mr Pattinson says.
Progress is well underway - the equipment has just been purchased.
The terrain is more than rugged. Its vicious country, its West Coast bush. When you look over it, it's absolutely stunning, but at the same time it is vicious, difficult country.
It's hard to believe there's a mine here, let alone a mine rescue here.
The rescue is a $22 million budget job. The PRRA is about to go for final sign-off from the Government.
One of the options is to build a new entry and exit, with a tunnel of up to 500m drilled in the side of the mountain, which would give an emergency exit.
Miners will have to camp there and everything dug out will have to be taken out - a massive job.
This is why the PRRA has asked the Government for more money - understood to be well into the millions as it pushes ahead.
"It's not a walk in the park. Even though it is a National Park, I call it Jurassic Park," Mr Pattinson says.
He explains it could be undertaken by the end of the year, a symbol the Pike River mission is making real progress.
Newshub.
