BIG POWER SCHEME

Southland Times, Issue 19294, 12 July 1924, Page 5

BIG POWER SCHEME

ARAPUNI CONTRACT LET

OVER ONE MILLION INVOLVED

A GREAT UNDERTAKING

HYDRO-ELECTRIC SCHEME. STATEMENT BY THE MINISTER. (Per United Press Association.) WELLINGTON, July 11. In a statement to the House of Representatives on the Arapuni power scheme, the Minister of Public Works said that after the examination of the tenders it was found that the cheapest alternative one, which at the same time was absolutely satisfactory from a technical point of view, was of Sir W. G. Armstrong, Whitworth and Company, at £1,175,652, their price being within less than one per cent, of the Departmental estimate. The Minister explained that tenders were called for the work in two contracts, one the dam spillway and part of the headworks, and the other for the erection of the powerhouse and installation of the requisite plant for a capacity of 60,000 horsepower; but the conditions said that preference would be given to the firm tendering for both contracts. THE WORKS DESCRIBED. VAST STOREHOUSE OF ENERGY. THE CONTRACTOR’S PLANS. (Special to the Times.) WELLINGTON, Juiy fl. In the course of an interesting interview Colonel Greenbrough, D. 5.0., R.E., of Sir W. G. Armstrong, Whitworth and Co., furnished details of his plans in regard to the contract, which is to be concluded in three years. PRELIMINARY WORK. “The first work to be undertaken will be the construction of a diversion tunnel, 25 feet in internal diameter, which is intended .to take the entire flow of the Waikato River,” said Colonel Greenbrough. Simultaneously the excavation of the power house site and the head race channel, also the dam foundations above water level can be proceeded with. Before the actual construction of the concrete dam can be begun, the quarry site at Muku Creek, 12 miles up stream of the dam site, is to be opened up, and means of transport for the stone for the dam between the quarry and the dam have to be provided. This will be one of the novel features of the contractors’ scheme, as it is intended to provide a ropeway between the two points, capable of delivering stone from the quarry direct into the storage bins at the dam, at the rate of 50 tons per hour. It is anticipated that it will be quite twelve months from now before this arrangement is completed, after which the concrete in the main dam will be placed at the rate of about 300 yards per day. The plant for this work will consist of a large number of air compressors, rock drilling plant, concrete mixers, steam navvies, cranes, locomotives, etc.

During the first year of the contract two villages, one temporary, for the workmen, and the other permanent for the operating staff of the completed works, will have to be built. The permanent village, which is to be put on the opposite side of the river to the power house, will be connected with the latter by a suspension bridge across the Arapuni Gorge. The lake which will be formed by the construction of the Arapuni dam will be about 18 miles in length, and the regulation of the flew at different hours of the day Which this lake will permit, will ultimately form one of the most important features of the power scheme, since it will enable the water to be stored at night to meet the next day’s peak loads. The lake will include one particularly straight and regular section 4 miles long, 30 chains wide and about 100 feet deep. Since the speed of the current in this portion of the lake will be quite inappreciable, it will form one of the finest pieces of water for boat racing in New Zealand. TREMENDOUS VOLUME OF WATER. The flow of the river is so ample and steady that more power could be generated at Arapuni than is yet required for the whole of the population of New Zealand for some time to come, and therefore there will be a considerable amount of water to spare. This will be discharged over a spillway weir and thence to a waterfall which will occur in the overflow channel. This fall will be 70 feet in height and at times of light loads or during a flood will have passing over it the greater part of the flow of the Waikato. To some extent this fall will resemble the Huka Fails, but being greater in both volume and height, it will form one of the most specular sights in the whole course of the Waikato.

POWER HOUSE PLANT. The power house will contain by far the largest turbines and generators in New Zealand. The size of these units are such that it is not easy to realise in advance just what they will be like. Each 25,000 horsepower turbine will be supplied with water from a pipe line 12 feet in diameter, reducing to 9 feet at the entrance of the turbine casing. Thence the water passes between guide vanes to the runner, which will be nearly 9 feet in diameter and about 4 feet in depth. The runner is the most important part of the turbine, and it is largely the careful design and manufacture of the runners that secures the high efficiency of the best modern turbines. Each turbine will weight over 100 tons, and above it will be placed a 15,000 k.w. generator weighing 250 tons. This generator will be 20 feet in diameter and the height from the base of the turbine to the base of the generator will be about 20 feet. The vertical shaft of each unit will be 20 inches in diameter, and besides transmitting the power of the turbine, will carry the whole weight of the rotation parks, and a hydraulic thrust estimated at 150 tons in all on to a thrust bearing of special type. Without the invention of this type of thrust bearing, the satisfactory operating of such large machines would be almost impossible. ASSET OF INCALCULABLE VALUE. The transformer will step up the electrical pressure to 110,000 volts for the transmission of power to Auckland and elsewhere. These transformers will be located in an outdoor transformer station on the top of the hill above the power house. They will be of the most modern type, and give an extremely high efficiency. The asset produced in New Zealand in the Waikato river is one of which the ultimate value is more than is generally realised. The huge machines which are now to be installed at Arapuni will generate only a fraction of the power which the dam will make available and the remainder of the power at Arapuni can readily be brought into operation as soon as the demand justifies the purchase of the additional plant and equipment, but Arapuni itself, though sufficient to meet, all that can be foreseen of our needs for many years o come, represents the utilisation of only 175 feet of fall out of a total of 1200 feet which the Waikato drops in its course from Lake Taupo to the sea. The final development, with a series of power stations developing in all over 1,000,000 horse power, represents a potential asset quite comparative for power purposes to the Niagara Falla.

FINANCING THE SCHEME. Although no definite statement was made by the Minister to that effect, he indicated to-night that it was probable that special finance provision to meet the expenditure involved in the construction of the Arapuni dam, headworks and power house, will be made from the Empire development proposals of the Imperial Economic Conference, which were subsequently accepted by the new British Government. New Zealand has already applied for £4,000,000 from the British. Government under this scheme, which makes it a condition that the money should be expended on public undertakings ahead of the ordinary development programme, provided the materials required for such works were secured in Britain. The J rime Minister, in making his application, indicated that the money was needed for hydro-electric works and railways. AT THE VILLAGE. Provision is being made for married quarters in the village, and it is intended to erect a large recreation hall for the workmen. It is expected that at least 600 skilled and unskilled men will be employed on the works throughout the contract. Nearly all of these will be New Zealanders, as it is intended to bring out from England only such few skilled men as are necessary for the erection of the electrical equipment. TRANSPORT OF MACHINERY. For the transport of the large quantities of machinery, cement, etc., which will have to be brought from the nearest railway station at Putaruru, ten miles away, large numbers of motor lorries and tractors will be required. For this a well-metalled road will be constructed. This will also be one of the first works to be undertaken. The enormous electrical units will be brought to this country in pieces, ranging up to .30 tons in weight and of dimensions which are too large to pass through the railway tunnels between Auckland and Putaruru. They will, therefore, have to be taken from the freight steamers in Auckland to Paeroa, where special equipment will be erected to handle the pieces. The erection of the powerhouse plant, which shall mark the completion of the contract, will be carried out during the last year, the time of the contract being three years.

ABOUT THE CONTRACTORS. The contractors, Sir W. G. Armstrong, Whitworth & Co., Ltd., have a world-wide name as builders of battleships and heavy armament. It is only within recent years that the firm has commenced undertaking large civil engineering contracts. At the present time they have under construction large harbour works at Lagon (Nigeria, West Africa) costing £1,000,000, a big concrete dam at Jamaica, a hydro-electric scheme at Humber Arm (Newfoundland) costing over £4,000,000 intended to provide power for wood-pulping mills, and several smaller contracts in Great Britain and overseas, inelpding the Waihi-Tauranga section of the East Coast Main Trunk railway costing £500,000. Among recent undertakings also is the building of locomotives for the South Australian Government. Sir Glynn West, who presided at the annual meeting of the Company held at Newcastle, England, on May 23, said that these locomotives would be the largest yet constructed in England. Last March an issue was made of £2,000,000 54 per cent, notes so as to increase cash reserves and enable the Company to carry out the Newfoundland contract. Fixed assets and investments of the Armstrong Whitworth firm at December 31 last were valued at £15,590,596 and stocks at £3,172,022. The share capital at the date of the balance-sheet was £10,012,500 in various denominations. THE TURBINES.

The large turbines of 25,000 horse-power each of the Arapuni scheme will be built at the Elswick works of the firm. The whole of the electrical equipment for the Arapuni scheme will be manufactured by the Swedish General Electric Co., one of the few firms in the world that have had previous experience of such high-powered electric plant as is to be installed at Arapuni. PERSONAL. Mr S. H. Bush, the managing director of this great firm, has been in Wellington throughout the negotiations in connection with Messrs Armstrong Whitworth’s tender for the contract. Colonel Greenbrough’s experiences in such an undertaking since the war have already been written up in this journal on the occasion of the firm securing the East Coast railway contract. During the war, he designed, constructed and equipped a number of inland ports, each capable of handling 3000 tons a day, on the French canals, including dry docks and workshops. The works in connection with the control of the defence of inundations behind the channel ports were also carried out by him.