STEAM BORES OF WAIRAKEI

Taupo Times, Volume II, Issue 69, 13 May 1953, Page 1

STEAM BORES OF WAIRAKEI

EPIC OF ENGINEERING Everyone who sees the steam bores that have been drilled in the eourse of the Geothermal Steam Project at Wairakei is impressed with a sense of the mighty foree that is being investigated. Those who have seen some of the bores "blown off" have found the sudden quicklymountifig roar of unleashed steam a startling experience. To stand for a moment or two within say, twenty yards, of an unsilenced bore has been found an uneomfortable experience by more than oue visitor. What is it iike to have to work right alongside these roaring steam jets? A Times reppresetitative who spent half an hour on Saturday morning last, watching work in progress on the biggest and deepest yet drilled, gained a little insight into thaproblem. Noise and Vibration. At eighty to a hundred yards from this 2,020 feet bore, which is ten inches in diameter at the top, the noise makes it neeessary to shout into a companion's ear to enable him to hear. As one approaches the bore y it is neeessary to hold one's hands firmly over the ears. Engineers and staff who have to work from time to time at the bores, to open or shut them, or to fit or observe testing apparatus, use ear plugs, and in addition find it adviseable to pad behind the ears, and then cover the whole ear and pad either with eloth bound tightly over the head, or with ear-pieces. With out such eomplete eovering the noise and vibration, conveyed through the bony structure behind the ear, even though the ears may be plugged, especially when men are working in the dug-out straight -below the opening of the bore, have been found to cause workers to lose their balance. The intense air vibration close to the bore can be felt both on one's clothes, and also in its effeet on the body, produeing a kind of vibratory feeling in the chest, _Jn the bottom of the concrete-lined dug-out, through the floor of which the bore-pipe comes up, and where the great valve is by which the steam can be turned on and off, the vibration and! noise is quite different from that experienced at ground level, where one's head is close to the level of the openjng of the bore. Men working on ihe valve find they must keep their | mouths elosed to avoid an unpleasant sensation and involuntary moving- of the jaw. Nerve Wracking Work. rfo the writer, standing alongside the extension wheel of the control valve, the shaft of which slopes down to the actual valve by way of the dhg-out -stanway, it seemed that the ■engincfcr m charge of drilling, Mr R. MeMillan, and the six or seven men with him, had a nerve-wracking job. 1 Tlieir alm was to shut off the great steam jet by closing the valve, so tnat preparations could be made for carryiug out various tests, the fitfcing of a separator to aeparate water from the steam. and so on. Severai men manned the wheel at the top of the dug-out steps, while a couple of others, with Mr MeMillan, assisted by manning the second wheel in the dug-out fitted on the valve itselfr It was an utter impossibility to hear a word, but the alert and experienced men on the job easily followed signals given them. As the wheels were turned the roar of ihe steam jet began to lessen a little, but soon the turning became harder, until the valve would close no fivrther. Such difficuties are not unexpected, of

cour.se. The valve was re-opened5 and then closed again, and, although the bore was still far from shut off, the needle of the gauge at the top of the dug-out steps crept round to show a pressure of more than 400 Ibs. to the square inch, equivalent to a weight of eleven tons on the under side of the valve. The roar of stearii decreased, a little more this time. it seemed, but again the valve would not close. Routine Work. AU this was routine, just part oi the job, to engineer and men. To the layman standing beside them, there came a feeling that seemed a mixture of nervousness and weariness. The noise, vibration, and sense of tremendous concentrated power, probably great er than that of a jet engine, seemed too much to endure for long. And five miles away over the hills, in Taupo, people paused to listen as they heard the deep-toned | roar of the bore wax and wane as the valve was turned on and off. After severai attempts, the job was left, for it has been found that not much more than half an hour can wisely be worked at a stretch in close proximity to the orifiee of the bores. On each attempt the valve opened a little more, and another attempt or two will probably close it. The enormous pressure of the steam can perhaps only be realiseo by a layman if he has stood, like the writer, for half an hour or so close to the open bore. To him, the scene seemed somebow to recall memories of warfare. Throughout the job, not a word was spoken. Nods and signs indicatejd what was required, occasionally a word or two was spelt out with finger tip on the

ground or eoncrete wall. As he watched the men go down into the dug-out, heated by the roaring steam in the massive pipe, he felt that this, like war, was a job where men wanted mates they relied on and leaders who gave them confidence.