I would suspect the decision on the type of mining would depend on the economics of overburden stripping?

Given the section of coal they have,and the estimated tonnage,it would be feasable to clear the overburden,

But the fact that it underlies Maori Tribal lands,was the reason that they had to drive a cross-measure level to intersect the seam as it rose on the back of the fault,not to cause disturbance to these lands.

With the potential problems associated with methane, was there a system of methane drainage in place? Or was it simply allowed to "dilute" into the general body?

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But the fact that it underlies Maori Tribal lands,was the reason that they had to drive a cross-measure level to intersect the seam as it rose on the back of the fault,not to cause disturbance to these lands.

Ahh, not just economics then.

The fact its 250 metres deep is likely to be the main reason for not strip mining. Thats a colossal amount of overburden, the environmental impact would be huge, forgetting the cost. The means of removing the methane was the main main vent fans, which is why the blast was triggered following their failure and why the methane levels built up again leading to the second blast. The main thrust of the investigation is likely to be: -

1. Did the management rules follow best practice for removing methane.
2. What actually led to the ignition of the methane, bearing in mind everything should have been intrinsically safe.

The fact there was methane there is of no real relevance as its par for the course in coal mining.

But the fact that it underlies Maori Tribal lands,was the reason that they had to drive a cross-measure level to intersect the seam as it rose on the back of the fault,not to cause disturbance to these lands.

Ahh, not just economics then.

The curse of a PC, apologetic government.

I was sat on a bus with a load of miners going up the West Coast of Aus and we were yapping about "the friggin abbos" and how they were incompatible with modern life and the government were bending over backwards to every whim. I gathered that a Uranium mine was closed due to it being sacred (some elder had his first whank there).

The chap also said "If ya take a pictya of an Abbo, you'll steal his soul, they don't like having their pictures taken"

Needless to say, on the trip, my camera took a fair load of souls! :lol:

Back to NZ, I really don't know how they talked of any survivors after the vent fan was blown off.

With such a rich sorce of methane comming from the Hawera fault why was this not tapped as a resource ?
after all the coal mined here was coking coal

Kellingley Colliery evacuated 200+ miners last night after a series of methane explosions undergound. HMI & MRSL called out - full emergency procedure invoked. Surprised its not already on this forum or that it hasn't made more than local papers' websites given the potential seriousness (and topicality following the Pike River story) Even BBC news North Yorkshire hasn't bothered to put it online!

Even Tower Colliery had a Methane drainage system,that powered thier surface,that being Steam coal.

Even Tower Colliery had a Methane drainage system,that powered thier surface,that being Steam coal.

Looking at the Tower pics they supplied the National Grid with surplus power.

Yes,thats correct,the same was done in Cefn Coed years earlier,but believe that was Gas that was supplied.

As was mentioned,strange the Methane was`nt tapped as an energy source for this Colliery,to reduce its running costs.

What may have gone wrong.

By Andrew Watson Operations manager of Mines Rescue safety training service


Pike River mine Rescue teams had been unable to go into the mine after the first blast because of toxic gases.

Following the very, very tragic accident in New Zealand, there will be the obvious comparisons between the events in Chile and New Zealand. But really, there is no comparison.

Chile was a hard-rock mine where the hazards are man-made. These can be controlled by ensuring high standards are adhered to and good planning.

With coal mining, there are additional hazards that occur naturally, such as methane, spontaneous combustion (fire), carbon monoxide and hydrogen sulphide and, because it is a soft-rock mine, the strata around the coal needs to be supported.

All of these are controllable by high standards, regulation and good management. But what could have gone wrong?

The initial explosion last Friday was a methane gas explosion, but the ventilation shaft should have ensured that methane did not build up to dangerous levels.
After explosion

Methane gas is explosive in atmospheric ratios between 5% and 15%. In coal mines in the UK, we aim for less than 1% methane. At 1.25%, the power automatically cuts off, and at 2%, all miners are evacuated.

At Pike River, the fact that there was an explosion suggests the methane reached 5% or more. So, either the warning system was inadequate, or it was not sufficiently monitored.

Once the initial explosion occurred, the following would have been lost:

* Communication
* Monitoring of the mine atmosphere
* Ventilation

In such cases, it means that rescuers don't have much information to work with.
Candles lit for the miners The second blast came hours after the first progress in days for the rescue attempt

In the case of Pike River, what they would have done immediately is gone to the return ventilation side of the mine and taken samples.

That would have told them how much methane, carbon monoxide and hydrogen was in the atmosphere at that point. What it would not have told them was what the conditions deep inside the mine were - which parts were safe and which weren't.

The explosion might have damaged ventilation equipment such as fans, ventilation doors and seals. It might also have caused rock falls.

The miners would have been trained in these situations to travel towards a safe haven. If this couldn't be reached, the hope is that they would have barricaded themselves in somewhere away from this toxic and noxious environment.
Rescue decision

At this point, the rescuers would have had to decide whether it was safe enough to deploy a rescue team into the mine to gain the information they desperately needed.

This did not happen at Pike River, so clearly the information obtained from the return side samples indicated that it was too dangerous to enter the mine.

Some people have accused rescuers of being too cautious, questioning whether a window of opportunity had been missed. They insist that emergency teams should have been sent into the Pike River mine soon after the initial explosion.
CEO of Pike River Coal Mine Peter Whittall Some members of the miners' families have criticised officials for not sending rescuers in sooner

The team would have had access to breathing apparatus - what we call long duration sets. These weigh 17kg (37lb) and last up to four hours.

But when you consider the distance that rescue team would have to travel, it is clear that the apparatus would have been right on the limit.

It was almost 1,200m (3,940ft) to the first cross cut, and 2,300m (7,545ft) to the end of the tunnel.

Double that distance - to get in and back out - and you are taking things to the extreme.

Now consider the conditions in the tunnel. It would be very, very hot - because the ventilation may well have gone. And, because of the rock fall, the terrain would be rough.
Too dangerous

This could have been challenging even for a fit team of rescuers.

So, instead of going into the mine to get this information, they drilled a borehole from the surface, which obviously took time. Once completed, it verified that the atmosphere inside the mine was too dangerous too enter and that the worst scenario for the miners had been realised.

From a rescuer's point of view, this is as frustrating and distressing as it can be. These men would have been trained to help and rescue their colleagues. It is in the nature of miners to work as a team and to help each other in this extreme environment, and that is what the rescuers would have wanted to do.

There is absolutely no doubt that, if it had been possible for them to enter the mine at any time, they would have done so.

These men would have been aware that the environmental readings were preventing this.

No doubt, in the days and weeks to come there will be much discussion about what lessons can be learned from this disaster.

Of fundamental importance is the need to maintain high standards.

Mining safety standards in New Zealand are very similar to those in the UK.

But, at Pike River, something went badly wrong leaving many questions unanswered.

http://www.bbc.co.uk/news/world-asia-pacific-11833033 

Two quotes from The Telegraph.

"While samples from the mine were still showing high levels of methane, indicating that there was still a sizable reservoir of dangerous gas underground and the risk of another blast, Mr Whittall said plans for entering the mine were being laid.
There were three options for making the mine safe, which involved using nitrogen or water vapour to disperse the dangerous methane, he said."

"All involved pumping new gases into the mine and removing the oxygen. Rescue teams using breathing equipment could then enter the mine."

It is a very sad outcome to the events at Pike River.
It makes me mad when people with no experience of Coal Mining rescue make prolonged statements as to why the rescue teams have been kept out of the mine.
Another thing that has been stated is that the safety regime is the same as in GB. The NZ government did away with there mines inspectorate and workmens inspectors and replaced it with a system of basic inspections by the mines own staff, not at all like our system here. With there being no mines inspectors therefore they have given emergency control to the police who are not mining engineers or experienced in mines rescue. 😞

A Scottish miner who works at Pike River has put some info on the Welsh Coalminers Web site.
He stated on it that the Police stopped the rescue teams that wanted to go underground to attempt a rescue from doing so.

The fact there was methane there is of no real relevance as its par for the course in coal mining.

I would suggest that methane was a major contributory factor in this terrible event, and whilst being "par for the course in coal mining" how it is dealt with is extremely relevant.

After the initial explosion, with subsequent loss of ventilation, methane, along with other harmful gases, would have built up in such concentrations to be well outside its explosive range, but would of course be detrimental to life. Whilst I appreciate the thinking behind the of drilling of a borehole into the mine (to monitor gases, etc) perhaps this "re-instatment" of ventilation, has in fact diluted the methane to a percentage that has become explosive again. However, there is still the question of the source of ignition?

The inquiry into this affair will no doubt highlight factors, but ultimately it can't change what has happened.

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This explains very well why the methane built up so quick after the first blast: -

http://tvnz.co.nz/national-news/mine-expert-first-explosion-ruptured-gas-line-spewed-methane-3916367 

There has been a third explosion at the mine. http://tvnz.co.nz/national-news/third-explosion-mine-site-3919278 

They are considering using GAG Unit (Gorniczy Agregat Gasniczy engine) to exlude all oxygen from the mine. It has been used successfully elsewhere in the world.
http://tvnz.co.nz/national-news/recovery-efforts-could-begin-monday-3916897 

The third (Australian) robot has reached 1.5km into the mine. The other two robots being damaged in the second explosion.

i've noticed that on all forums re pike river mine disaster cannot get information re whether CH4 drainage via directional drilling was undertaken. Has to be viewed as mandatory in a gaseous pit. i worked as a team member on CH4 drainage team for 10 years in underground mines and know first hand the deadly consequences of inadequate gas drainage.
It took a gas explosion and death in my pit with ensuing improved drilling techniques/practices recommended by the coroner to safeguard against further blowouts/explosions.
Also monitoring of gas levels at each drill site. ie a more concerted effort by management to balance desire for production with as safe working conditions as humanely possible.

It appears looking at one of the New Zealand TV links, there was a gas drainage system, as the main discharge pipe was damaged in the first explosion which led to the rapidly increasing methane levels following.