Tears were shed in March 2012 when state-owned coal miner Solid Energy bought Pike River Coal, the company that failed after an explosion ripped through the West Coast mine the previous November, killing 29 men.

“I don’t mind admitting I cried with some of the other family members,” Pike River families spokesman Bernie Monk told Stuff at the time. “To me, we have people in place we can trust and that we can have a dialogue with.”

Events over the intervening years have turned optimism to bitterness for Monk, whose son Michael died in the disaster. The relationship became so acrimonious, the families eventually refused to meet Solid Energy officials.

Earlier this year, Solid Energy was forced to put out public statements about previously unreleased video footage of mines rescue workers tending to a smoking robot three months after the explosion. The company directors denied they were part of a cover-up and said the footage didn’t mean the mine was safe for re-entry.

Monk tells Newsroom that Solid Energy never wanted a manned re-entry to the mine and refused to meet the families’ experts, who thought it was possible. Taking the re-entry plan out of Solid Energy’s hands is “the best thing that ever happened to the families”, he says.

For its part, Solid Energy chief executive Tony King says his company is disappointed plans for an unmanned re-entry have been terminated by the new Government. The company had decided on a suitable robot to do the job and selected a borehole site. It had also applied to WorkSafe New Zealand for exemptions from mine regulations, over operating in a mine ‘chock-full of methane’.

King: “Solid Energy’s involvement at Pike River has been fraught at times and it would have been nice to finish our involvement there on a positive note, of having successfully finished that re-entry project and having found whatever we found. We’ve got no stake in whether bodies were found or whether evidence was found or not, but it would have been nice to be able to accomplish something rather than just have it end halfway through, as it did.”

King is confident the robot – which hasn’t been built, but designs are finalised – was suitable for the job and could operate in the mine.

“I guess the one big question mark, that is an unknown until you try, is what you encounter once you’re down there and, in particular, how much debris is there. Because while the machine is a pretty capable little machine, and they’re quite widely used around the world, if it turns out there’s a lot of debris on the floor – there’s pipes and conveyor belts and that sort of thing – it may simply be unable to progress as far as we might want. But without actually going in and seeing, we can’t know.”

400m left unexplored

All but 400m of Pike River’s 2.3km access tunnel, known as the drift, has already been explored by remote robots. There are about 5.5km of tunnels in the mine “workings”, where coal was being extracted. The workings are blocked by a large rockfall.

In November 2014, three years after the Pike River disaster, Solid Energy ruled out re-entry to the mine as too risky. But the previous Government asked Solid Energy to come up with an unmanned re-entry, to determine if any human remains could be found in the unexplored 400m of the drift and possible discover the cause of the initial explosion, which a Royal Commission into the tragedy could not definitively determine.

Under the Official Information Act, Solid Energy has released to Newsroom its spending on the project. It has spent $177,000 on consultants and contractors, including Garden City Helicopters, specialist drilling firm Ecodrilling Ltd and Nexxis, an Australian company which makes robotic crawlers. And about another $173,000 on internal salaries and operating costs to manage the site.

(An October 26 briefing from the Ministry of Business, Innovation & Employment said the overall budget for Solid Energy’s unmanned exploration was $2 million, with a further $1 million earmarked for an unmanned probe into the mine workings. The briefing said the robot would take up to four months to be built and delivered.)

Solid Energy also released to Newsroom two reports written since April – when the terms of reference for the project were confirmed.

The report contains discussions between various unnamed experts about the difficulties of drilling a borehole above the mine site, through which a robot would enter the mine.

One person calls one possible drill site “pretty steep” and suggested workers “level the pad site with explosives”. A 15m-20m-high bluff directly below the drill site showed “recent drop-outs, overhangs and blocky joints”. A geotechnical report into stability was recommended.

Another unnamed expert said possible borehole sites were “very approximate” because the GPS signal was “very, very poor”.

There were also warnings about the hardness of the ground, which was thought to be granite from the surface to the mine’s drift. An expert said a colleague had to get special core bits from Australia to drill test holes “and progress was very slow”. That person said his preference was to drill an angled hole through the coal seam – something Solid Energy ruled out because of potential difficulties with retrieving the robot.

The other Solid Energy report is a 33-page design study into the possibility of drilling a 150mm-wide borehole to put in what’s called the “drift exploration crawler”. The report was finished on September 29 – the Friday after the general election.

Robotics company Inuktun Services, which is headquartered in Canada and has Nexxis as its Australian agent, wrote that it “foresees no significant problems in addressing the challenges” of re-entering the mine. The report outlined an expected 140-metre borehole to be drilled to the top of the drift. The robot, attached to an electrical tether up to 300m-long, would weigh between 54kg and 64kg and be lowered at about 10m per minute.

Design elements to control static electricity build-up included making all linking and chassis parts from un-anodised aluminium, which are electrically insulating, and using grounded metal wheels and rollers on the robot’s track belt.

To stop sparks possibly igniting methane in the mine, through the robot or tether hitting things, Inuktun suggested using anti-static skid plates on the outside of the robot. A nitrogen compressor could have been used to avoid introducing oxygen to the mine.

The robot would have automatically powered down if its internal temperature reached 80 degrees. Camera lights would also be dimmed. Recovery of the tether past the “bore breakthrough” in the ceiling “may be the most significant problem”, the report said.

Sunk by multiple problems

Solid Energy went into voluntary administration in August 2015, brought down by a mixture of problems, including its aggressive pursuit of alternative energy projects, hundreds of millions of dollars in debt, and plunging coal prices.

In March next year, six years after Solid Energy’s purchase of Pike River Coal, the state coal miner will be wound up. Before that its Pike River Coal assets – including information for an unmanned re-entry – will be transferred to a new Pike River recovery agency. The Pike River site and all associated assets and information will be transferred to the agency before Solid Energy is wound up.

The Minister Responsible for Pike River Re-entry, Andrew Little, says he’s in possession of quite a few “helpful” Solid Energy reports, monitoring information from the mine and images from previous robotic devices. What they point to, he says, is the feasibility of a manned re-entry to the drift. He notes Solid Energy’s prototype robot hasn’t been developed and there are up to five robotic devices already stranded in the drift.

“I’m not sure sending yet another device in – which would probably have to be dropped in through a yet-to-be drilled borehole at the mine workings end of the drift – is going to be very helpful.”

Monk, whose family owns Greymouth’s Paroa Hotel, is dark about Solid Energy’s pursuit of an unmanned re-entry, saying: “In my eyes, they’ve wasted a huge amount of money doing this job.”

As soon as the new agency is set up, new plans for a re-entry will move “very, very quickly”, he says.

“Put it this way, our experts are ready to go now.”

Last month, the Supreme Court ruled WorkSafe unlawfully withdrew charges laid against Pike River Coal chief executive Peter Whittall, after he agreed the company’s insurers would pay $3.41 million to the victims’ families.

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

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