A former Pike River Coal mine manager was working up to 110 hours a week, often on crisis management, before leaving just weeks before the mine exploded, killing 29 men, a hearing has been told.

The Royal Commission of Inquiry into the Pike River mining tragedy has been told there was a "revolving door" of managers at the West Coast mine.

Former technical services manager Pieter (Petrus) van Rooyen moved to the West Coast from Namibia in February 2009, and left 16 days before the explosion.

The very day he started, the main ventilation shaft collapsed.


He worked 70-90 hours a week, even logging 110 hours at times, due to continual changes in the mine design and increased reporting to the board and bank as the newly developed mine under-performed.

He came to New Zealand for a better lifestyle so after Pike River took a position in Reefton at the Oceana Gold mine, where he seldom worked nights.

While at Pike River he was determined to maintain professional standards and make good decisions.

"That's why I worked such long hours," he told the hearing.

He said too much of his time, and consultants, was spent on crisis management. By the time he left, a viable medium term plan had been developed.

Mr van Rooyen said he did not suggest a second escapeway should be built before hydro mining began because he "knew what the answer would be". The Department of Labour has implicated hydro mining in the disaster.

"The company focus, as conveyed to me by Gordon Ward and Peter Whittall, was on the need to produce coal as soon as possible.

"There was no way that the company would delay coal production."


He disagreed with the location of the fresh air base, which was too close to methane drainage lines.

But there was a lack of co-ordinated design and development.

"In many ways I felt that mine design was being effected on the run, with little in the way of co-ordinated overall planning."

Pike River is believed to have been the only mine in the world with its main fan underground.

A consultant suggested to the inquiry that it should have been placed above ground, by the portal.

On October 5, 2010, the mine was gassed out after the fan was damaged. A subsequent internal report raised significant issues, from lack of communication underground, to gas monitoring.

Then the roof in the 'goaf' collapsed, damaging a 'stopping' (airflow barrier).

When asked if hydro mining should have continued, given those problems, Mr van Rooyen declined to answer on his lawyer's advice, to avoid self-incrimination.

However, he did say he was concerned hydro mining began before the main fan had been commissioned.

"I don't know who made the final decision."

He firmly rejected claims by Japanese hydro mining expert Oki Nishioka that he was scared to go underground.

The hearing continues.