The ventilation shaft at the Pike River mine has been successfully capped.
A helicopter operation at the mine today saw two 770-kg semi-circular steel plates fitted into place over the ventilation shaft, secured with sandbags.
The operation was completed shortly after 2pm.
Police Superintendent Dave Cliff said weather conditions had improved sufficiently to allow the capping to go ahead.
He said it was good news for the ongoing operation.
"We're hopeful the cap will help to improve the effectiveness of the GAG engine, and stabilise conditions inside the mine."
Superintendent Cliff said gas levels would be closely monitored for several hours.
If the environment stabilises, the GAG engine will be shut down
temporarily for maintenance, and more concrete will be added to the sealing of the portal.
Monitoring of oxygen levels will continue and the GAG will only be
reactivated as required.
A Floxal nitrogen-generation unit is now on standby in Brisbane, and
arrangements are being made to bring the unit to New Zealand later in the week.
This would pump nitrogen into the mine to reduce the temperature, Superintendent Cliff said.
Meanwhile, police have reassured the families of the 29 men that although the current operation is being scaled back, they will continue to provide welfare support and coordination.
"Police will also retain a longer-term presence in Greymouth, with our
investigation team leasing premises in the town for at least the next 12 months."
- NZHERALD STAFF