An investigation report reveals why police dismissed a possible cause of the second Pike River mine explosion, but some victims’ families are unconvinced.

It was the explosion that ended hope for the families of the 29 Pike River men.

At 2.37pm on November 24, 2010, a second explosion rocked the West Coast coal mine, turning what had been a rescue operation into a recovery. (That recovery is ongoing, with confirmation from the Pike River Recovery Agency this week that its workers have reached the 170-metre barrier, which is to be re-sealed.)

Last September, a Newshub report said police were investigating whether the cause of the second explosion was someone starting a conveyor belt in the mine tunnel, known as the drift. Dean Dunbar, whose son Joseph was killed at Pike River, had spent the last two years investigating the theory. The TV news story centred on “rarely seen footage” of the second explosion from the mine portal and a “clunk” sound.

The mine re-entry was meant to start on May 3, but was delayed because of unexplained gas readings. A ceremony at the mine involving families and politicians, including Prime Minister Jacinda Ardern, still went ahead.

The day after, on a Saturday, police issued a press statement saying its “thorough and detailed” investigation had concluded. “Police have found no evidence to suggest that the conveyor belt was operated or started at any time after the first explosion.”

A 19-page report, released to Newsroom under the Official Information Act, summarises the police investigation. However, Bernie Monk, who lost son Michael in the disaster, says he and Dunbar are convinced there are problems with police conclusions.

Police point to ‘substantial evidence’

The police report says not only is there “no evidence” the belt was started, there’s “substantial evidence” to suggest it wasn’t.

The passworded, touch-screen controls to the belt were in an unlocked shed at the right-hand side of the mine entrance. The summary document states it has been “established beyond doubt” the belt couldn’t be started from the control room.

In particular, the report addresses allegations that “some rogue employee” started the belt. To do so, the report says, they’d have to: get to the portal, a restricted area, open the laptop, bypass and turn off alarm systems, have knowledge of the start-up sequence, and turn the belt on.

Witness statements and video evidence suggest no one was at the mine portal for 50 minutes before the second explosion. Electrical contractor Electronet confirmed power was on to the conveyor belt on November 25. But the data show no power surge between the first explosion, on November 19, and when the circuit breaker was opened on November 30.

The police investigation has its shortcomings, however. Officers were unable to interview “several of the key witnesses”, many of whom left New Zealand after the explosion and remain overseas.

In particular, police couldn’t track down Peter Whittall, Pike River’s former chief executive. His evidence at the Royal Commission was that it was his idea to start the conveyor belt. “The action was never taken. It was deemed that it wasn’t necessary.”

Police report summarising t… by on Scribd

Monk, whose family owns Greymouth’s Paroa pub and hotel, says some families of the victims are not convinced by the outcome of police investigation into the conveyor belt issue, which has been reviewed by their own experts. They’ve asked to meet with the police experts but have been stonewalled, he says.

In its conveyor belt investigation, police spoke to two unnamed witnesses – one of them almost certainly Dunbar – who said they were told by a third party who said the conveyor belt had been turned on. One even said the source was a “member of the NZ Police” but they refused to provide a name.

Families of the Pike River disaster victims have been dogged in their quest for justice, and haven’t been shy about airing their concerns in the media.

In 2017, there was controversy over footage – supposedly suppressed – taken within four months of the last explosion that might have shown intact bodies. After WorkSafe dropped charges against Pike River Coal boss Peter Whittall in exchange for a $3.4 million payment, two of the victims families fought that deal all the way to the Supreme Court, and won.

Re-entry became an election issue in 2017, with Labour promising to establish a Pike River Recovery Agency. Ten days before election day, Labour leader Jacinda Ardern visited the Pike River Memorial. (New Zealand First leader Winston Peters famously pledged in 2016 to be the first to re-enter the mine.)

“The proposal to turn it on was not supported by police … due to the possibility of it acting as an ignition source.” – police response coordinator

The police summary report confirms a “proposal” to start the mine’s conveyor belt was made by Pike River Coal Ltd representatives.

Confirmation came from police’s response coordinator, whose name is redacted in the report but is named by the Royal Commission as Assistant Commissioner Grant Nicholls. Nicholls says in the conveyor belt report: “The proposal to turn it on was not supported by police … due to the possibility of it acting as an ignition source.”

A risk assessment was written by staff from the “Pike River Coal Mining Company”, Nicholls said, using an incorrect company name, and forwarded to Police National Headquarters for consideration on the evening of November 21, 2010. The assessment “doesn’t adequately address the risk of a further explosion”, Nicholls says, and no one from police signed it, suggesting it “was not finalised or approved”.

An unnamed police witness didn’t recall signing the risk assessment. Another said the belt turn-on wasn’t actively pursued “to my knowledge”, and the emphasis of the rescue operation leading up to the second explosion was on gas testing, deployment of Defence Force robots, and drilling a new bore hole.

Pike River’s engineering manager – named by the Royal Commission as Robb Ridl – told police no standard operating procedure document was completed for the conveyor belt turn-on before the second explosion. “I do not believe that any person would have attempted to start the conveyor belt without a standard operating procedure being produced and without all the controls in place identified in the risk assessment.”

Pressure wave moved belt: expert

Police commissioned an independent review of the explosion’s video footage. That expert found it was “very unlikely” the movement of the belt was “initiated by people”. “It was more likely caused by the pressure wave of the second explosion.” The short lag time between the movement of the belt and the pressure wave arriving was noted, and the belt moved in the opposite direction to its normal operation.

A gas expert said for the explosion to be initiated by a belt start-up there would need to be an explosive atmosphere of gas around the conveyor belt system or associated electrical circuits. But the belt only went as far as the “grizzly” – the feeder and sizer machine for the conveyor, about 2.1km from the portal entrance.

“There is no evidence that the atmosphere at the grizzly was anything other than fresh air,” the expert says. (In saying that, a solid energy monitor at the grizzly wasn’t working on November 24.)

A police photographic analysis indicated airflow from the mine caused the explosion was “possibly” the cause of the belt movement.

Copping criticism

Police haven’t been blameless through the Pike River saga.

The Royal Commission highlighted problems with the initial operation, including “the transfer of key decisions away from experts at the mine site, the lack of early planning on survivability and the slow risk assessment process”. In a 2012 debrief, police admitted crucial parts of its evidence-gathering during the disaster were “disorganised” and “diabolical”.

But the police role in the $36 million mine re-entry will be crucial to the victims’ families hopes of charges being laid against the Pike River Coal Ltd executives. Police Commissioner Mike Bush spoke at the Government announcement last November that the mine would be re-entered. He said: “Our case is open and everything will be based on evidence.”

In February, police said they would have an “agile” approach to the re-entry, and the safest option was for police staff to wait until the entire 2.3km “drift” tunnel to be recovered before entering. However, that approach might change in the case of a “critical find”.

David Williams is Newsroom's environment editor, South Island correspondent and investigative writer.

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