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Pike River re-entry team review potential risks

World Coal,


Solid Energy’s work to review the potentially fatal risks in re-entering the main drift at Pike River has highlighted a number of interconnected issues, according to CEO Dan Clifford.

Risk assessment

Clifford explained: “Public discussion about this project seems to be looking for a single issue, something which might explain why Solid Energy has taken this time to decide if the remaining work can be done safely.

“In fact, there are a number of elements which, together, make undertaking the job safely much more complex, and it is well known that complex projects – where you need everything to work as planned – are inherently more risky than straightforward ones.”

The “single entry issue”, having no alternative way out if the drift becomes blocked, is one such factor.

Rescue plan?

“A basic tenet of risk assessment is that you plan and be ready before something is needed. The single entry is a factor which increases risk to life because if something does go wrong and people become trapped, we have to consider how we would keep them alive until they could be rescued, what we would do if someone in the team was badly injured and things like the type of equipment we would need on hand to effect such a rescue.

“I’ve heard people say that this is just a big tunnel built in strong rock so there’s little chance of anything going wrong there. That is simply not correct. We know that the roof has already fallen at the top end and we suspect there has been a more recent fall further out. We know that it has been subject to enormous stress, with four explosions. We know that in the last 300 m it is not strong rock. It passes through a major geological fault where all the surrounding material is fractured. We know that the type of rock changes to sandstone in places and the drift passes through a coal seam. You look at all that, and it would be just foolhardy to say this is a simple rock tunnel.

Gas dangers

“Another complexity which adds risk is the reality of a gassy coal mine at the far end. Again, people look at the conceptual plan and say, well you just block that off with your temporary seal and it’s not an issue any more, but again that’s not correct. That seal, even with a perfect placement, will still leak. Making sure no methane leaks into the area where people would be working and no oxygen leaks back through into the old mine workings will be incredibly complex. We will need to continually balance the pressure on both sides of that seal for many days or weeks and use an inert gas to create a barrier between the oxygen and methane and that will rely on several things and people all working exactly as planned.

“There are many things which might go wrong with this, including not being able to get people up onto the mountain because of bad weather, or the generators failing and losing electricity up there, or losing electricity to the fans at the bottom. All these things have happened in the past, so we need to plan for them. Obviously, if the drift was open and clear we would have time to safely pull the team out if one of those things went wrong but, again, what about if they were trapped and we no longer had sufficient control of these elements and started to get toward an explosive mixture again in the mine? It’s another complication that needs to be considered because it is possible this would happen and if it happened, people could be killed.”

Addressing the challenges

Clifford said the company has been drilling down into each potential issue over the past few months.

“So far we are looking at more than 600 controls being in place and all of them working correctly even before anyone starts into that drift. You can’t just say, ‘she’ll be right, we’ll deal with it when we get there’. We’ve looked hard at all these potential complications and challenges and worked out how to avoid them happening, or reduce the chance of them happening, and what we might do if they did happen.

“The question is not whether the job can be done. It is whether, when you look at all the remaining risks even after all your controls are in place, you are prepared to accept that risk to your people and that is the call only Solid Energy can make,” he concluded.


Adapted from press release by Katie Woodward

Read the article online at: https://www.worldcoal.com/coal/25092014/piker-river-team-consider-re-entry-risks-1356/


 

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