'Symbolic' re-entry of Pike River Mine set to go ahead today

Today, families of the men who were killed underground the Pike River coal mine will witness the "symbolic" re-entry after more than eight years of waiting.

The official re-entry is due to take place this morning, two and a half weeks after it was postponed because of problems with gas-monitoring equipment.

Newstalk ZB's Rachel Das is at the Pike River Memorial Garden, down the road from the mine, where she can hear the river rushing behind.

She said there is a rock for each of the 29 men who died eight and a half years ago.

Das said you could see blue sky behind the mountain, beneath which their bodies lie.

She said cloud is drifting and lifting, and families are hoping today might be the day they finally re-enter.

Three experienced miners, headed by Dinghy Pattinson, will go into the mine.

The plan is to go to the initial concrete seal where no one has been since it was closed up years ago.

The miners will open it up, go beyond it, and see what they can find, begin the investigation and see if there's any evidence.

The Pike River families are meeting at the mine gate at 10am.

Pike River Recovery Agency chief executive Dave Gawn said yesterday his team had cut through the concrete seal which provided a means to ventilate the mine drift.

Assuming favourable weather conditions and no other last-minute issues arising, the agency will re-enter the Pike River Mine drift today, Gawn said.

Gawn said at the request of the families it will be low-key and private for the families to watch the opening of the double airlock doors and re-entry team stepping through.

The re-entry is a long-awaited goal for the families of the 29 men who died following the 2010 explosions in the West Coast mine.

Sonya Rockhouse, whose 21-year-old son Ben was killed, said the families had thought it would be nice if the event was for them only given how long they had been in the media spotlight, she said.

A well-publicised re-entry attempt was planned for May 3 but called off by the Pike River Recovery Agency the day before for safety reasons.

Prime Minister Jacinda Ardern, who visited the families ahead of the May 3 attempt, said the decision was made then that any future attempt should be left to them.

"It is really a symbolic moment. Re-entry to the drift is going to take a number of weeks and months," she said yesterday.

Families were disappointed by the delay but accepted safety must come first.

The agency had been working for months to purge methane and oxygen from the mine by pumping in nitrogen before they were to head underground.

But the day before they were due to go in, they got an "unknown reading of oxygen" from a borehole 2.3km into the mine's drift, where the roof collapsed in the 2010 explosions. The oxygen had the potential for a "spontaneous combustion event".

A leaky sampling tube was to blame for the oxygen spike and was replaced before work on cutting into the concrete seal resumed.