KAIMAI INQUIRY ‘Too Much Left To Tunnel Manager’

Press, Volume CX, Issue 32321, 12 June 1970, Page 24

KAIMAI INQUIRY ‘Too Much Left To Tunnel Manager’

(New Zealand Press Association)

HAMILTON, June 11.

The resident engineer on the Kaimai Tunnel, Mr J. D. Benn ion, said today he now believed he had left too much of the construction adjustments to his tunnel manager to work out.

Mr Bennion was giving evidence in Hamilton before the Commission of Inquiry- into the disaster of February 24. The commission comprises Messrs A. W. Yortt (chairman), K. E. Andrews and F. J. Hancock.

Mr Bennion. called for re-examination, spent more than three hours in the witness box this afternoon.

He was asked by Mr Andrews whether he now thought he had left too much to his tunnel manager, “and very well experienced practical people of his type.” Mr Bennion: I am aware that in retrospect the Austrian system of timbering (which in early December re placed the Hallewell construe tion method) was not sufficiently detailed by engineers. The evolvement of a system like that is between engineering and field staff. In that re spect I think I left too much to the tunnel manager (Mr A. I. Wotherspoon) to work out

Mr Bennion said that if he had his time over again he would still not continue with the original Hallewell method any longer than he had (from early November to early December). “In mv opinion it would require ver’v substantial modifications.” he said.

For the Hallewell scheme to work effectively two things were necessary which could not be applied, he said. “It was essential that it should be possible to excavate safely a face of 150 degrees and from the material encountered from the time we went underground this was just not possible,” Mr Bennion said. “It was also essential that adequate footing be found in the bench so footblocks could be placed, and under the circumstances this proved to be impracticable.”

A Compromise? Mr Yortt: Do you think that In retrospect if you had had more men and better equipment you might have been able to make the Hallewell system go? Was what you did a compromise of the men and equipment you had? Mr Bennion said he had mentioned extensive modifications to the system. Had he had more resources it might have been possible to make those modifications on the site. To Mr Andrews he said that after hearing evidence during the inquiry he had changed his opinion of where he thought the original run of material, before the main fall, had started. He agreed with Mr Gilheany, a tunneller who had been working in the collapse area, that it had probably started between the fourteenth steel set and the first timber set—just ahead of the

(face where he had first be- ; lieved it originated. ; Mr Bennion said he was troubled by criticism of communications. There had been some difficulties in com- ■ munications with the district office in Hamilton because of delays in replies to correspondence. However, he had kept the office in the picture by telephone on a regular basis and believed communications from his end had been adequate. This morning Messrs Andrews and Hancock questioned the construction superintendent on the project, Mr L. I. Wills, on methods employed in building the tunnel.

Tunnel Machine

The District Commissioner of Works in Hamilton (Mr R. E Hermans) said it was likely that even more practical difficulties could be expected in the tunnel when the tunnelling machine was brought on to the project. Mr Hermans, answering questions under re-examina-tion, said the Ministry of Works had no practical experience with tunnelling machines. “However. I don’t think we would be any less capable than private contractors from this country or overseas,” he

said. “Geological conditions in New Zealand are quite different. I would say without a doubt that tunnel-bpring contractors would be less competent than we would be ourselves.” Mr Hermans said he and a retired Commissioner of Works, Mr Lang, had inspected machines in use overseas, and on their recommendation the Government had since ordered one for the Kaimai project.

He told Mr Andrews: “1 certainly don’t think the wrong decision was made in tackling the job with our own forces.” He had been asked if the ministry would have been in as good a position to tackle the job as private contractors who had employed some of the ministry’s best men. He was asked by Mr Andrews whether he thought it had been fair of the Ministry of Works to saddle Mr Bennion, with his tunnel experience, with a job that was going to be a difficult one.

Shortage Mr Hermans: 1 don’t think the responsibility of carrying out the necessary work was beyond the capabilities of Mr Bennion.

He agreed with a suggestion from Mr Andrews that not only in the ministry but throughout New Zealand there was a shortage of engineers sufficiently experienced in tunnelling to take on a residency such at Kaimai. The inquiry is expected to enter its fourth week on Monday, according to the secretary of the commission (Mr J. Smith). Since the inquiry opened on May 25, 26 witnesses have given evidence. At least six more—four for the Ministry of Works and two for the Department of Mines—are expected to be called.