SUBSIM Radio Room Forums - 29 miners trapped in NZ

They are most likely dead.:nope: Here's hoping the experts are wrong.

Rescue team can't go in till the methane gas clears otherwise they could all die from another explosion. There are gas pockets throughout the 2.5 km tunnel.

Quote:

A West Coast geologist warned about the threat of explosions from gas in the Pike River mine more than three years ago. And a second mining expert says initial investigations of the mine were inhibited because of its location in Paparoa National Park.

Meanwhile, Canterbury University geologist David Bell has admitted his fears for the 29 trapped men, saying: "I don't believe the guys down there have got a hope."

Western Exploration director Murray Cave said in 2007 that the geological risks at the underground site included a pit bottom with deep, highly gassy coals and the associated risk of "outburst", or gas explosions.
He warned of the presence of an underground fault that had to be crossed at the mine site and pointed to Solid Energy's short-lived Mt Davy mine, which was shut in 1998 after three miners were killed in two accidents.
Yesterday, Mr Cave said the Pike River coal was at the "higher end of the scale" for gaseousness, and each tonne contained about 10 cubic metres of gas.

The head of New South Wales' mining engineering school Professor Bruce Hebblewhite said extensive work was done before mines started operating to determine methane quantities.
Levels varied depending on the depth of the coal seam and how permeable it was – which affected how easy it was for the gas to escape.
Sometimes methane could be drained before mining started, but it was more usual for ventilation systems to be used. "Every mine is dealing with it all the time."

As methane was highly explosive, electricity supplies were tripped so power was turned off if concentrations of the gas rose.
"You need it to be 1 per cent and below to be really safe. Then you enter the explosive range."
He added that the presence of the Hawera fault zone running through the mine could be an additional source of methane.
However, measuring and predicting the methane content in advance of mining would have been incredibly difficult.
"If it's localized pockets it's like looking for a needle in a haystack to drill in."
Canterbury University engineering and mining geologist David Bell also said the fault running through the mineshaft allowed pockets of methane to build up.
"It seems to me that there's been a significant methane explosion underground. I don't believe the guys down there have got a hope – I've got to be perfectly honest, it's most unlikely somebody has managed to survive that, but I hope like hell they all survived.
"You have got to remember they are 2.5 kilometers in from the portal. They don't have a lot of exits. Once you have a fire you starve that place of oxygen."

The Hawera Fault had traps and pockets where methane could collect in splintered coal seams, Mr Bell said. "The early work on Pike suggested it was a very simple situation where basement rocks were thrust up over the coal seam, but the reality they found was there were splinters that had not been picked [up].
"They didn't do a whole lot of [investigative] drilling earlier on because it was inside a national park, so you have very tight restrictions on where you can go and what you can do."