Arapuni Comes Through!

Sun (Auckland), Volume III, Issue 678, 1 June 1929, Page 15 (Supplement)

Arapuni Comes Through!

Arapuni power—a dream and its realisation. Almost a generation has been added to the long span of time since the dream of power from the foaming Waikato first took vague and shadowy shape in the minds of men who were at first derided gently as visionaries. Some of the men whom the dream inspired have gone different ways. Some are overseas, some are in retirement, some are dead. But east of Mount Maungatautari there is a proud monument to their farsightedness. And the dream stands, frozen into the solid substance of steelwork and masonry, a triumph prodigal of electricity, the potent spirit of the age. Let the processes that have gone to this achievement be divested of their material associations, separated from the complex details of contracts, plans, man-power, and quantities, and the response of a distant river to the need of a throbbing city has about it all the romance of fabled mysticism. Power from the great central reservoir of Taupo and the snowy spurs of majestic mountains, applied through a finger-switch to a bedroom light in Auckland—that surpasses the legend of the magic carpet. No more wonderful was Aladdin’s lamp than this strange harvest from the Waikato that sends its power across leagues of varied country to be transmuted in far-distant factories into the wealth that is more than gold. Not without many trials has this wonder been encompassed. So severe have been the difficulties that perhaps some of the glamous has departed. Yet its fine lustre is there. The dream of Arapuni has about it all the quality of an epic achievement in New Zealand’s national history.

* lake’s broad surface used to tie jnp, there is little to suggest that it is a source of infinite power. At this spot there is none of the turbulence into which the stream begins to break lower down. It is clear and placid, and in summer the grinning young Maori boys, perhaps clad in Mature's vestments only, wait upon the wharf for tourists to come along and toss pennies into the crystal [water. But only a few chains below the butlet the current starts to accelerate its pace. There is an ominous Swirl or two, and perhaps the chalky crest of a rock breaking the surface. Jn coquettish fashion the Waikato changes from a tranquil waterway to a river of whirlpools, cataracts and rapids, breaking its course every mile or two down the long stairway to Cambridge, where it once more becomes placid and sluggish. Riding seaward in sharp waterbreaks or billowing curves, the Waikato stages its first grand spectacle at the Huka Falls, where it loses its lade-green tints in a smother of foam, compressed between walls of rock in a narrow gut that ends abruptly where the river drops 30ft into a seething cauldron. A few miles further down the river drops another 100 ft at Aratiatia Rapids, a little over half a mile long, and perhaps the grandest spectacle in New Zealand. By building a dam at the head of the Aratiatia Rapids, engineers estimated that they could develop 135,000 h.p. over a head of 175 ft. The scheme would have meant the obliteration of the Huka Falls, and was rejected in favour of Arapuni. The long sequence of rapids is Maintained at intervals past Orakeihorako and Atiamuri. The bed opens put a little above Arapuni, and then, m days gone by, it narrowed again •o begin its spectacular passage of the Arapuni Gorge, which before the hydro works began was a place of sheer loveliness, with immense buttresses of weathered rock breaking through curtains of dense forest that almost hid the foaming river from view WASTED HORSE POWER Mew Zealanders were long con«aouß 0 f the j mmense power that was running to waste at these beauty “Pots, but not until just before the . ar was any definite plan formuated. Ultimately Mangahao, Waiaaremoana and Arapuni were tentatively adopted as the principal power ources for the North Island. In the oouth. Lake Coleridge was developed tter the passage of the Aids to water-power Act in 1910. The war eid up progress With the major :' orth Island plan, but after the war J? 8 requisite appropriations were ade, and after considerable contro-

versy Arapuni was definitely adopted, and tenders invited. Before specifications for the job could be drawn up the country had to be tested, and considerable drilling was undertaken at the present site of the dam, tunnels being driven far below the riverbed. For such a big contract the specifications were of a most elaborate nature. The contract w.- ’ivided into two. No. 1 section covering the dam and headrace, and No. 2 the powerhouse and plant. The departmental estimate of the cost was £1,168,277. The following tenders were received:- £ Sir W. G. Armstrong, Whitworth and Co 1,175,157 J. G. White and Co 1,534,483 Hansford and Mills .. .. 1,695,157 By adjustments between the Public Works Department and the lowest

tenderers the contract price finally got down as low as £1,170,991 13 Bd. No. 1 section was to cost £610,375 and No. 2 section £565,082. The work was to be completed in three years, that is, by August, 1927, and the department on the strength of this arrangement agreed to supply power from Arapuni to the Auckland Power Board by April 1, 1928. In the light of subsequent knowledge it was seen that the estimates of the cost of the job were too low. The contractors had agreed to make provision against floods in which the volume of the river ran as high as 14,000 cusecs, but in October, 1926, a flood which played havoc on the job ran as high as 24,000 cusecs, the biggest volume the river had carried since 1907. This flood submerged the powerhouse working? and led to

the long idleness in that part of the job. Delay was seen to be inevitable, and after a lapse of further time the Government was compelled to spend something like £60,000 on German submarine engines, which were installed at the Penrose sub-station, and helped to carry Auckland’s load last winter. The man in charge at Arapuni when Armstrong, Whitworth’s were in charge was Mr. P. W. A. Handman, who formerly had executed a big power scheme for the Brazilian Gi vernment on the Rio Grande del Norte. When the Public Work Department took over, the man in charge, at first, was Mr. D. Dinnie, now Public Works engineer at Napier. With him was Mr. T. Rabone, who carried out the final part of the work.

FOURTH UNIT IN HAND A major attribute of the Arapuni scheme was its capacity for great extension. The original tender provided for three units, and accordingly three penstock tunnels were driven, and three sets of turbine gear ordered. Lately it has been decided that the growing demand for power warrants installation of a fourth unit, and tenders for the supply of the necessary gear have been let to A. S. Paterson and Co., by whom the earlier plant was supplied. Much of this was of Swedish make and a number of Swedish engineers, headed by Mr. H. Y. Overgaard, came out to supervise its installation. For the fourth unit another penstock tunnel will have to be driven, but this does not represent a very difficult piece of work. The penstock screens and other equipment at the intake are already in position. While Arapuni was in the making, nearly a qurater-of-a-million was spent on transmission lines to carry the power to centres of demand, chief of which was Auckland. For a number of years the only big cross-country transmission line in the province was that from Hora Hora, built by the Waihi Goldmining Company in 1911, to its stamping battery at Waikino. Then came the big line from Arapuni to Penrose, close on 100 miles of wire traversing the country in almost a dead straight line, and built to carry current at the terrific pressure of 110,000 volts. Except in a few places in the United States, current is not habitually delivered at a higher voltage, with its implications of danger in case of accident or carelessness. Between Mangahao and Wellington, however, the same voltage is employed. Automatic trip-out switches coming into operation at once in the event of a break in the line, help to minimise the danger. At Penrose the current is “stepped down,” and is delivered underground to the King's Wharf at 22,000 volts. So comes Arapuni to Auckland. Away back in the ’sixties, when Sir George Grey first systematically exploited the Waikato by placing on it the gunboats Pioneer, Avon and Koheroa for use in the Maori War, he could not foresee that in the future, not half a century after his time, the great possibilities of the Waikato as a waterway of commerce would become subordinate to its importance as a source of electric power to light distant cities and drive distant mills. But today that miracle has come to pass, and although Arapuni may already be an accepted fact in our midst, it behoves us to be not unmindful of the advantages its development has brought.