Pike River: bags covered up gas sensors

Flames coming out of a ventilation shaft at the Pike River Mine. Photo / APN

Plastic bags were placed over gas sensors and explosives were used in an unsafe manner inside the Pike River mine, its "gutted" former safety manager says.

Neville Rockhouse is giving evidence to the Royal Commission of Inquiry into the Pike River mine disaster that killed his son Ben and 28 other men.

Another of his sons, Daniel Rockhouse, was hailed as a hero after surviving the first mine blast and helping another man to escape the mine.

Mr Rockhouse said Daniel had since told him safety breaches were common inside Pike River.

Those included placing plastic bags over gas sensors, impairing the ability to pick up spiking levels of potentially explosive methane, he said.

He claimed explosives were used to help spread bags of stone dust against the walls of the mine - a process aimed at preventing coal dust explosions.

"I was absolutely gutted. I couldn't believe it. We'd put so much work into that place....It's beyond comprehension... The rules of mining are written in blood."

Mr Rockhouse also spoke about falling out "big time" with former Pike River chief executive Peter Whittall.

"He'd give me a hard time but he'd also give a lot of the other managers a hard time.

"He could be a very intimidating man and a lot of the people on site were intimidated by him, that's fair to say."

Mr Rockhouse said his relationship with other managers disintegrated until the point he could not handle it.

At one point, a fellow manager told him to "keep your bloody nose out of it" when he had offered advice on a report.

He resigned twice and was talked out of his decision each time.