Wheao power scheme savable—-inquiry

Press, 5 July 1983, Page 1

Wheao power scheme savable—-inquiry

PA Rotorua The Rotorua Area Electricity Authority believes it will have the Wheao power scheme working by the end of summer, after the release of what it sees as a favourable Government inquiry report yesterday. The Committee of Inquiry has said that it would be viable to rebuild the power scheme, partly destroyed last December. A canal bank on the nearly completed $35 million project in the Bay of Plenty broke after water leaked into its foundations, sending more than 200,000 tonnes of water and a mass of boulders and debris tumbling down a steep gully and into the powerhouse. No-one was at the site at the time.

The report of the inquiry made no definite conclusion regarding what caused it, but found “in broad terms” that water had leaked into “tricky” geological formations in the foundations.

But in spite of this, the committee said that it felt the cost of restoring and commissioning the scheme would not be so high that the project should be abandoned altogether. The chairman of the Rotorua authority, Mr Alan Mills, said the report was pleasing in that it drew the same conclusions that the authority had reached using independent consultants. This meant that costing and planning for reinstatement along lines recommended by the committee was already under way, he

said. Mr Mills said a special meeting of the authority would probably be called next week to draw up final estimates of costs and then an approch would be made to the Government for “several million dollars” extra loan finance to rebuild the Wheao scheme. The merits of such an application for finance would have to be evaluated by the Committee on Local Authority Hydro Development before the Government responded to the proposal. The inquiry report said the future costs of restoring and commissioning the project could not be given with any reasonable degree of accuracy until various site investigations and redesign

studies had progressed further.

The Minister of Works, Mr Friedlander, in releasing the report said that the committee had concluded that the engineers who carried out the site investigation and designed the scheme had done so “in accordance with acceptable practice.”

But he said some aspects deserved more consideration.

In particular, the involvement of engineering geological* expertise should have been continued throughout the scheme’s construction and a better-detailed connection should have been made between the canal’s

earth lining and butting concrete structures.

Also, in critical areas, the committee indicated that a more sophisticated lining system, preferably concrete, should be provided to cope with geological conditions. But the inquiry found no significant criticism of the construction work on the project and concluded that there were no reports made before the accident which, if heeded, could have prevented it.

The committee suggested that an independent technical review panel should be engaged to advise on the adequacy of any work on the scheme’s reconstruction.

Mr Brian Underwood, a director of Murray North Partners, Ltd, the firm

which acted as consultants to the Rotorua authority for the scheme, said the committee’s report was “fair and reasonable,” and made constructive recommendations concerning the completion of the project. With the benefit of hindsight the company agreed with them, Mr Underwood said.

Mr Underwood who was consulting engineer for the project, said there had been extensive publicity regarding the use of brown ash as a canal lining.

He pointed out the committee’s finding “that Murray North took careful heed of the cautionary warnings made by the Ministry of Works and Development

and Department of Scientific and Industrial Research concerning the use of brown ash as a canal lining.”

The president of the Contractors’ Federation, Mr Bill Auld, said the inquiry report justified the federation’s confidence in the ability of its members to handle large power construction projects.

The inquiry did not question the quality or performance of the construction, he said.

Mr Auld said that there were important economic consequence when failures such as the Wheao collapse occurred, and contractors would support any moves to

ensure they were not repeated.

The Government review of planning and building procedures for small power schemes should be finished in the next week or two, said Mr Friedlander yesterday.

The review was ordered after the Wheao canal collapse and after an earlier failure on the Ruahihi scheme.

The investigation into the safety of such structures is being carried out by the Ministry of Works.

Once it was finished, Mr Friedlander said, the Government would consider whether any changes were needed to make local authority hydro schemes safer.