Masaoki Nishioka, who has 40 years’ experience in underground mining, resumed giving evidence at the Royal Commission Inquiry into the Pike River mine tragedy yesterday, where he described the situation at the mine as “really scary”

He had concerns over the mine’s inadequate ventilation system, high methane levels and he believed the goaf of the mine would become a methane pocket.

Nishioka said the safety issues at the mine were advanced and felt it had to go back to fundamentals, which would include replacing the mine’s fan and putting it outside the portal.

He said it would require the operation to shut down for at least six months to a year.

The inquiry heard Nishioka was happy to leave the mine when his contract ended on October 20, 2010, despite only starting three months earlier.

"From the beginning to the end I didn't feel comfortable staying at the mine at all, that was why I was pleased to go,” he said.

"It was really risky to go underground … the operation wasn’t organised.”

In the lead-up to his departure, Nishioka’s concerns surrounding the mine’s soaring methane levels continued to grow and by the time he left, he was too scared to go underground.

The commission heard that on his last day at Pike River, Nishioka had predicted a tragedy at the mine was on the horizon.

He told Pike River’s hydromining coordinator George Mason “this mine could explode”

Nishioka said he “couldn’t guarantee” whether an explosion would occur but the situation was as bad as he indicated.

He said he didn’t expect staff to talk to management but Mason reassured him he would be careful.

Nishioka revealed everyone at the mine feared the “worst-case” situation, apart from the miners who didn’t have experience in underground mining.

“The situation was really, you know, scary, that was my feeling,” he said.

Nishioka also raised his safety concerns with another fellow colleague, Lance McKenzie.

“He was a good friend of mine and I told him frankly, you know, this mine could go anytime so please be careful here,” Nishioka said.

During evidence, he said his methane concerns for the mine could be managed by putting in a bleeder, which would minimise the volume of methane accumulated in the goaf.

Nishioka said the suggestion wasn’t carried out by the mine’s management and to his knowledge, Pike River Coal had no plan to manage the mine’s methane levels.

“I don’t think, you know, anybody had any idea how to handle methane readings in the goaf,” he said.

Nishioka said he told PRC chief executive officer Peter Whittall about his concern with the mine’s methane levels and confided in him his worst-case fears for the mine.

“Everybody knew the worst thing could happen … that’s why I gave strong words to Peter Whittall when I met him [the] last time in my office,” Nishioka said.

He said when Whittall stepped into his office and asked him how things were going, Nishioka sternly told him everything at the mine was wrong.

However, the conservation between Nishioka and Whittall was later disputed in the inquiry by lawyer Paul Radich.

“Mr Whittall will deny very strongly indeed that you made any comment to him at any time about safety concerns in the mine or safety of the men in the mine,” Radich said.

Radich said Whittall would claim the issues raised by Nishioka were merely “general operational issues”