Pike mine entry delayed
The Pike River mine has been purged of methane and oxygen in preliminary tests but plans to reenter the mine have been delayed.
The Government previously said re-entry of the mine would be completed by March but authorities now say it may not begin until then.
Twenty-nine men died in a series of explosions at the West Coast mine in November 2010.
Pike River Recovery Agency chief executive Dave Gawn said re-entry would begin no earlier than the end of February.
Meanwhile, purging tests carried out before Christmas reduced methane levels in the first
180 metres of the mine drift (or access tunnel) from 96 per cent to about 2 per cent, and oxygen levels dropped to less than 1 per cent, agency chief operating officer Dinghy Pattinson said.
‘‘It happened quicker than we thought, so it was great to have these early tests,’’ he said.
‘‘We’re restarting purging tests [yesterday] – the more information we have on the speed the nitrogen pushes up the mine to displace the methane and maintain a stable environment, the better it is for our planning towards re-entry.’’
Agency mining staff have been trained in using a new
950-kilogram venturi destined for a Pike River Mine borehole.
The venturi was fabricated at Gray Brothers Engineering in Greymouth and, once installed, will extract nitrogen and methane from the mine drift.
In late February, the venturi will be flown by helicopter to the borehole site in three main parts and reassembled on site.
Pattinson said purging would continue for 12 hours a day, seven days a week, while data was gathered about gas levels in the mine.
The installation of the portal emergency doors is continuing.
The doors are now in place and the winching system has been attached to the outside of the portal. Work to seal the area around the doors will continue over the next few weeks.
Miners are also continuing to lay 9 kilometres of pipelines above the portal, which will take nitrogen up to boreholes in the mine workings and drift.
‘‘They’re more than a third of the way through, but ahead of schedule because the weather has been great.
‘‘Some of the more difficult terrain is to come though,’’ Pattinson said.
The drilling programme started this week, with the first of three new boreholes for gas monitoring drilled into the drift access tunnel, about 1400m from the portal, on Wednesday.