'Crucial' evidence recovered from Pike River mine drift

Tuesday, 1 December 2020

Families gather for the 10th anniversary of the Pike River mine disaster at the Atarau memorial near Greymouth. (Video first published November 19, 2020)

A vital clue into what might have caused the Pike River mine explosion has been unearthed from inside the mine.

The recovery team at Pike River has recovered a large chunk of metal understood to be a piece of the main ventilation fan. It weighs about a tonne and is about 3 metres long.

The Pike River Recovery Agency is recovering the drift – the 2.3-kilometre mine access tunnel – in a $51 million Government-funded project aimed at looking for bodies and evidence of the cause of the disaster to help a police criminal investigation.

Twenty-nine men remain entombed in the mine after the first of a series of methane explosions on November 19, 2010.

A large piece of debris recovered from the Pike River mine drift.

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The recovery team first entered the drift last year and is now in a previously unexplored end of the drift leading up to a rockfall which blocks entry to the mine workings.

Electrical engineer Richard Healey has spent 18 months on a private investigation into what happened at the West Coast mine.

He said when he saw the photograph of the debris he recognised it as a section of fan casing.

It would have been blown 46m from the main ventilation fan and hit the wall of the drift “like a cannonball” at the point where the roof collapsed.

“To make it through the twin, steel, rated ventilation doors it had to have been carrying considerable kinetic energy,” said Healey, who has the support of some Pike River families.

Map of Pike River mine from the royal commission which shows the area around the slimline shaft that was filled with concrete in 2011.

A logical conclusion was that it was not only the cause of the roof collapse, but the force needed could also mean that the fan was the location of the first explosion, he said.

The fan was a “critical” piece of evidence into what might have caused the first explosion.

According to the royal commission into the disaster, the main ventilation fan being located underground was a world first and had not been properly risk assessed.

A ventilation consultant and staff had been against its installation at the time.

Electrical engineer Richard Healey has spent two years investigating the Pike River disaster.

The royal commission also found that at the time of the first explosion, the main ventilation fan failed and was not explosion-protected. The back‐up fan at the top of the ventilation shaft was also damaged.

It said a possible ignition source for the first methane explosion was arcing in the mine’s electrical system.

Healey hoped the agency would put a camera down a pipeline which runs from the drift into the mine workings.

Pike River Recovery Agency workers are re-entering the 2.3km mine access tunnel.

The 30cm-wide pipeline installed to pump water into mine was contained in a report written for WorkSafe in 2012, which said it was possibly missing a section near the mine’s main ventilation shaft.

The main ventilation fan sits at the bottom of the ventilation shaft.

“We need to know what’s at the far end of that pipe. It wouldn’t cost the Government much money to put a camera down and have a look.

“The investigation is just beginning. We have found out what questions we need to be asking and the answers lie behind that rockfall,” Healey said.

The journey down the Pike River mine drift.

An electrical switch cabinet from the fan blew out of the ventilation shaft during the first explosion – and has been misplaced, along with 52 pieces of evidence that were destroyed by police.

A police spokeswoman said police first became aware of “speculation” on the switch cabinet in February 2019.

“While we have seen photos of the item we have never had possession of it. The location of the switch cabinet remains unknown,” she said.

“To maintain the integrity of the operation we are not in a position to speak to the specifics of the activities being undertaken at the mine site or what may or may not have been located or what activity we will be carrying out.”

When approached for comment the agency referred Stuff to police.

Pike River Recovery Minister Andrew Little said the agency was taking a methodical, fact-based and safe approach to recovery of the drift.

“It is not engaging in speculation about what may or may not be possible.”

He has previously ruled out asking Cabinet for more money for the agency to recover the mine workings.

* Correction: An earlier caption on a photo in this story incorrectly stated a methane leak was found in a pipeline. The Agency confirmed the pipeline readings showed nitrogen, not methane.