Weakness at Arapuni

Sun (Auckland), Volume IV, Issue 1009, 27 June 1930, Page 12

Weakness at Arapuni

MINISTER’S REPORT TO HOUSE

Geological Position

Press Association WELLINGTON. Today. NO time tvas -wasted by tlie House of Representatives yesterday in opening a discussion on the problem of Arapuni. Almost as soon as the formal business of the House had been compdeted the Minister of Public Works, the Hon. W. B. Taverner, rvas hearing questions from all quarters and. though he had not intended to make his first comprehensive statement until today, he %vas compelled to produce it at once to ward off persistent inquiries.

\ In his statement concerning tlie pesl- | tion at Arapuni, made in the House of Representatives today, the Hon. W. B. Taverner, Minister of Public Works, traced the history of the trouble from the time the cracks first developed. It was apparent almost from the first, he said, that extensive work would be necessary to make good the position and that the plant would of necessity have to be shut down for a consider- j able period. The entire emptying of the lake was therefore decided upon. As soon as it became evident that it would be necessary for the plant to shut down Auckland was communicated with and arrangements were made with the Auckland Power Board for it to take up its own load at its King’s Wharf steam plant. Arrangements were also made to get steam on the department’s steam set at the Grand Junction mine and ateo to ensure that the department’s Diesel plant at Penrose was ready for immediate service. It was also arranged that all power available from the McLaren's Falls plant, which belongs to the Tauranga Borough Council and from which the ‘ department has in the past taken power over a considerable period, should be drawn upon. Further, the Government’s plant at Rotorua, which . has been shut down for some time, was also got ready for immediate action. As a result when the water fell too low for the machines at Arapuni to operate the load was taken up by the : plants indicated, in addition to the department’s station at Horahora. and . has been carried in this way ever since. POWER SURPLUS AVAILABLE The total estimated power amount available is 19,150 kw., and the amount of the present load is 18.000 kw. Thus there is at present an estimated surplus of approximately 1,150 kw. The director of the Geological Survey branch of the Scientific and Industrial Research Department proceeded, to Arapuni immediately after the trouble occurred, and after further examination when the headrace was laid bare he consulted with the head: of his department. The Minister in j charge of that department agreed that; a technical committee, consisting of the head of the department, Dr. Marsden. Dr. Henderson (director of the Geological Survey branch), Dr. P. Marshall (member of the staff and at one time professor of geology at Otago University), and Professor J. A. Bartrum (professor of geology at the Auckland University College), should further examine the position and make a joint report. This they have done. A summary of the report is as follow: EXPERTS’ REPORT “A block of country near the penstock tunnels, between the spillway and the power-house, broke away at 1.30 a.m. on June 7, developing a crack extending along the front of the penstock tunnels and spillway. Water poured into this crack. developing hydrostatic pressure, which bent the block, including the power-house, progressively over toward the river. This bending extended over two days while the base of the cracks filled up with grit, allowing fuller development of the pressure. It is evident that the block moved about a base well below tlie river level, that is, some 300 feet below the penstock head. “After the diversion tunnel at the dam was opened and the level of the water in the penstock head began to recede, the block moved slowly back by about three-quarters of its original displacement and the leaks were reduced in greater proportion. It appears evident that the movement of the crack after its original formation can be accounted for by the hydrostatic pressure of water entering the cracks, and the question naturally arises as to the origin of the original crack and whether or not further disturbances are likely to occur. “Several alternative explanations may be advanced to account for the original rupture:—The whole block of country may have been in tension from natural causes and the extra excavation for the new power-house, together with hydrostatic thrusts in the penstock head, may have just caused the limit of resistance to be overcome. This seems the more likely explanation. “Alternatively, it is possible that water leaked into deep vertical joints below the penstock head, developing I sufficient pressure to cause a rupture. No evidence, however, can be found of j such joints in the absence of deep bor- ; ings. A third possible explanation is J that the stress was caused by a pos- j sible earthquake wave which, owing to : { the fact that the power-house and pen- ; stock head were rigidly tied, might j I possibly cause such a, rupture. Against j i this is ‘lack of observation of any such j tremor. It is true that the initial j J movement of the block caused tremors j and vibrations of the block which were observed by a man living in a hut near the penstock head. The cracks in the power-house, however, do not necessarily indicate a disturbance of the power-house foundations, since they consist of a transverse crack of the whole building at the point where its width changes suddenly and cracks round the supports of the heavy generators and turbines (350 tons). NO ROCK MOVEMENTS “The rock surfaces visible indicate no movement of rock masses relative to one another. The whole occurrence might well be unforeseen and due io an unexpected weakness of the support of the whole block which has I moved. This supporting material is only just strong enough to withstand the weight of the overlying rock without failure. Further buttressing of the whole block would appear necessary • to prevent a recurrence of the move- | ment and leakages of water from tlio ; forebay. . . | “The geologists are of the opinion f there was no undue water percolation | from the spillway into the block of I rock between the spillway and the 1 gorge and power-house previous to the | formation of the crack. Thus the initial movement is unlikely to be due to this cause.” The Minister added that realising the magnitude of the issues at stake and also the uneasiness which had arisen in the public mind, the Government had decided to obtain the very best engineering advice that could be obtained and with that object in view had been in communication with the High Commissioner for New Zealand in London, the president of the Institute of Civil Engineers and organisations elsewhere in order to select . the most suitable man. WORK TO DISCONTINUE “Until such time as the report to be made by this engineer has been received 1 have felt it my duty to advise the Cabinet to discontinue any further works at Arapuni,” he said. : “Further investigations will include a survey of the financial position of the ; scheme and will deal with the ecoj nomie aspect. In the meantime I wish to make the following observations: "The amount already invested in the

Arapuni scheme, including substations j and transmission lines and works in ; progress, is £2,500,000. In the year j before the Arapuni scheme came into j operation the working charges for the j Waikato system amounted to £76,231 • and the standing charges for interest j and depreciation and renewals were ! £74,571, or a total of £150,802. For the year ended March 31 last the re- ; spective figures were £62,702 and ; £195,752, altogether £258,454. so that ! the difference amounting to £107,652 j represented the additional total op- 1 eration costs of Arapuni for the year. The units sold for the year from the ! whole Waikato system were 191 millions, and the net revenue after paying working expenses of £72,702 was ; £162,981. “The average operating capital for : the year was £2,649.000, so that the i net revenue over and above working i expenses was 6.15 per cent, on operat- j ing capital, notwithstanding that the plant installed was insufficient to take j the whole of the available load during i the earlier months of the year. The j present installed capacity of the Ara- | puni station is 45,000 k.w. and consists j of three units. A fourth unit is now j in process of shipment from England ■ and had the course of events not been I interrupted would have been installed I on arrival, thus bringing the total capacity of the Arapuni plant to 60,000 kilowatts. “In a subsequent statement details will be given showing the cost involved in calling into operation the standby plants and other stations which were required to take the load when the supply ceased from Arapuni, but it may be remarked that the estimate at present for the generating costs at those stations is at the rate of £85,000 per annum as against £12,000 for generating costs had Arapuni continued in commission.” DUNEDIN STATEMENTS REASON FOR CONTRACTORS’ WITHDRAWAL DEPARTMENT’S REPLY THE SUN’S Parliamentary Reporter j WELLINGTON, Today. j The Public Works Department has replied a.s follows to the statements made by a Dunedin engineer regarding the abandonment by Armstrong. Whitworth and Company of the Arapuni ■ contract, allegedly because the com- j pany realised that the formation of the country round the dam made it impossible to carry on: “The absurdity of the statements should be apparent to anyone who knows the first thing about the Arapuni scheme, but as there are many people who are not familiar with the details, it is perhaps as ■well to point out that at no time did Armstrong, Whitworth and Company express any fears concerning the foundation of the j dam; at no time did they ask for varia- I tions, but as a matter ol’ fact they pro- j ceeded without interruption and fin- i ished the contract. “The statement that the company only proceeded after receiving the Public Works Department’s engineers’ guarantee is incorrect. No guarantee was given with either contract. A great deal of investigation was done in con- ; nection with the dam, but in connec- I tion with the power-house the con- | tractors were required by the specifica- 1 tions to make their own investigations and design a power-house which suited the conditions as found. “The argument between the Government and Armstrong, Whitworth and Company referred not to the dam, but to the under-water portion of the power-house. Armstrong-Whitworth and Company contended that this could not be unwatered. “At no time did they express any un- j certainty with regard to the portion of j the works where the present difficulty j has occurred.” PROBLEM OF SUPPLIES GOVERNMENT TO CONFER WITH BOARDS WILL EXPLAIN POSITION THE SUN'S Parliamentary Reporter | WELLINGTON, Today. j j The power boards in the Auckland j • district which have been receiving | supplies from the Government will j confer with the Minister of Public { Works, the Hon. W. B. Taverner, in \ Wellington on Monday. The Minister expects then to be in a position to explain the provisions the Government proposes to make for the future supply of power. Members of Parliament for the areas affected by the closing down of Arapuni will be invited to attend the conference. This announcement was made by the Minister late last evening, following a conference with Mr. W. J. Holdsworth, chairman of the Auckland Electric-Power Board, and Mr. R. H. Bartley, general manager of the board. “The conference is for the purpose of explaining the department’s proposals,” said Mr. Taverner. “Doubtful points can also be cleared up. The proposals I will then be in a position to make will give the necessary assurance in regard to future supplies. I am unable to indicate the nature of ! those proposals until they have been ! further considered by Cabinet.” j “As the conference was a private one i there is nothing I can say except that ] from our standpoint the discussion was j very satisfactory,” said Mr. Holds- | worth when interviewed later. “It ; will not be necessary for me to return | for Monday’s conference as the Min- ! ister will simply be explaining the I arrangements he has made with the Auckland Board.” Mr. Holds worth and Mr. Bartley left for Auckland today. INFORMATION DEMANDED HOUSE WANTS ALL DETAILS COMMITTEE OR COMMISSION? THE SUN’S Parliamentary Reporter PARLIAMENT BLDGS., Today. : Before the Minister of Public Works i made his statement on Arapuni yesterj day.( Mr. R. Semple (Wellington East! asked if a committee representative of j all parties of the House could be ap- . pointed to inquire into the causes of

the earth movements, the committee to have power to appoint outside experts if necessary to assist in its inquiries. The Leader of the Opposition, the i Right Hon. J. G. Coates, asked if the j Minister would make available all the results of his investigations and the j reports on the scheme since its initia- j tion, construction and development. He j asked that a Royal Commission be set ■ up with a judge presiding, so that the whole question would be lifted beyond the bounds of political controversy. The Prime Minister, the Hon. G. W. Forbes House wou taken into the full confidence of the Government on the subject. The question of whether there should be a committee of the House or a Royal Commission was one for future decision. In the meantime the position was being dealt with. Mr. Semple here laughed scornfully. POWER FOR COUNTRY ATTITUDE OF AUCKLAND BOARD I WILL DO BEST FOR FARMERS J'rom Our Oxen Corresponds lit TE AWAMUTU, Today. The reported attitude of the Auck- i land Power Hoard regarding conserv- ! ing all available output from its' auxiliary electric plants while the Arapuni power is cu' off, was explained to Mr. D. McArthur, secretary-manager of the The Awamutu Electric-Power Board, white he was in Auckland recently. In an interview with Mr. R. 11. Bartley, manager of the Auckland Board, the latter said the position was misunderstood. His board had fully considered the possibility of supplies being insufficient for the dairying industry, especially when the milking season . was at its height. As a matter of fact, by carefully husbanding all the available power in the city and neighbourhood, his board computed that there would be available for the farmers several thousand kilowatts, and this would be distributed in conjunction with the supplies from Hora \ Hora and other subsidiary plants. The farmers, said Mr. Bartley, could disabuse their minds of the impression that the Auckland Board was adopting a “grab all” policy. On the contrary, it realised that the continuance of the dairying industry, with as few restrictions as possible, was of very great importance to the City and its industries. He would positively give the assurance that everything possible would be done for power consumers in the country districts. Mr. McArthur thanked Mr. Bartley for his assurance, and said the farmers themselves would be greatly relieved to hear of his clear statement of the position.