Wheao inquiry told of previous leakages

Press, 4 March 1983, Page 3

Wheao inquiry told of previous leakages

PA Wellington The inquiry into the collapse of the Wheao canal late last year heard yesterday that during the disaster water had gushed from an area where leaks had occurred before.

The deputy chairman of the Rotorua Area Electricity Authority which was building the $25 million scheme, Mr D. C. A. List, one of the first persons on the scene after the collapse on December 30, told the inquiry he had seen water coming from the same place where leaks had been found earlier, on November 23.

The inquiry also heard that the penstocks in the area

where water breached the canal wall had been shifted 70 metres from where it was planned to build them when the scheme was first devised by the consulting engineers, Murray North and Partners. Ltd.

In answer to questions by the committee as to whether the canal failure had been caused because advice from the Commission for the Environment about the use of brown ash for canal lining had been ignored, Mr K. J. Miller, a recently retired secretary of the Rotorua Area Electricity Authority, said that it had been warned that brown ash was a difficult material to work with. He said that this had been taken into account during construction.

The authority’s engineer, Mr L. Riley, said he believed Murray North and Partners had done substantial tests including construction of a test canal to ensure that brown ash was a suitable lining before it was used. In another submission yesterday,, a Titirangi resident, Mr Donald Watson, called on the committee not to over-

look the possibility of sabotage. He said he was unable to offer any direct evidence, and that it might be that no evidence existed, but he said it was prudent to consider the possibility of sabotage.

“As you will be aware, over the last few years there have been many disasters in this country which can be traced to some act or omission of man, as distinct from an obvious act of Nature. You must also be aware that there are many disaffected elements here, one or more of which may be willing and have the means available to perform acts of destruction as opportunity offers.”

Mr Watson said that he had no evidence of sabotage, but he put the point forward as a theoretical possibility. After submissions by the electricity authority and Murray North and Partners — which submissions will be released to the news media today — the committee inquired whether they considered sabotage was likely. Both parties discounted the possibility. Earlier, Mr K. M. Allen, of Teal Electrical, Ltd, Rotorua.

who was the first person to arrive on the site during the collapse, said that he crossed the Wheao Canal (upstream from the powerhouse) about 7.30 a.m. and did not notice any difference in the canal.

He then drove down the canal, and noticed that a bypass valve at the Flaxy powerhouse (above the Wheao powerhouse) which had caused problems in the past was leaking. He stopped and inspected it, but still noticed no difference in the canal water level.

About noon the powerhouse area was inspected and it was found that the whole of the generator-turbine pit and most of the powerhouse were filled with boulders, mud, and silt. The confluence of the Rangitaiki and Wheao rivers (downstream of the powerhouse) and the bank of the Wheao River were inspected to see if any damage had been done to the riverbanks in the area where river training works had been done. The river at the time (1.45 p.m.) was still very discoloured, but appeared to be about normal level.