Re-entry into the Pike River coal mine moved a step closer with the crucial installation of a nitrogen-producing plant to remove the dangerous levels of methane from the closed-off mine drift.
Pike River Recovery Agency re-entry chief operating officer Dinghy Pattinson said the hired plant was briefly run this week to pump nitrogen through pipes at the mine portal, before bad weather prompted its shutdown.
“We'll be running the plant every week day through to our Christmas closedown,'' he said.
The plant is important to re-entry as the Pike River mine workings and main access drift tunnel are at present currently full of methane, which is dangerous when mixed with fresh air, and the nitrogen will displace it.
Pattison said the plan is to conduct a safe manned re-entry based on filling the tunnel with fresh air, so people going into the drift can breathe normally without breathing apparatus.
To purge the methane gas, two 4.5 kilometre polythene pipelines are being laid up the hill above the portal, so nitrogen will be able to be pumped into boreholes at the top end of the mine.
Three new boreholes will be drilled in the New Year, two to assist getting the nitrogen in and the third to monitor gases in the mine.
The intention is to flush the methane from the mine using nitrogen injection from the portal seal, with the methane discharged from the mine through boreholes.
*Simon Hartley is senior business reporter and assistant chief reporter for the Otago Daily Times.