ARAPUNI TROUBLE

Auckland Star, Volume LXIII, Issue 182, 3 August 1932, Page 8

ARAPUNI TROUBLE

SEEPAGE IN HEADRACE.

NO STOPPAGE OF WORKS.

STATEMENT BY MR. F. W.

FURKERT,

SPECIAL SHAFT SUNK,

To ascertain the origin of the leakage Trhich. has occurred in the headrace of the Arapuni hydro-electric works divers are now at work and a special ehaft has been sunk on the assumed line of infiltration. The lowering of the water in the headrace is continuing, and at midday the level was down by over four feet. The actual seepage, which is appearing in waterfall form in the gorge wall in the viehrity of the powerhouse, is reported to hare decreased in volume last night. At present there is no intention of closing the works, and the official iiew is that the trouble is not iniinedittely eerious. ■ • An outline of the position to date was given this morning bj' Mr. F. W. Furkert, Enginecr-in-Chief of the Public Works Department, who acturned to Wellington yesterday after visiting the works. Although he does not regard the seepage as serious, he said that if the quantity of water percolating through materially . increased it might &ave a. serious effect on the works. The water .running away was fairly considerable; but the actual leakage, according to - the , latest reports,- was found tthis ■ morning to be smaller than last »ight. . . . '. ■

Not Through Impervious Layer. In pursuance of the recommendations «f Professor P. G. Hornell, a drainage h.yer had been provided under the imjervious layer;in the headrace to enable abater which got through to be drained «ff.- The present seepage was not occurring through the impervious layer, but vaa escaping, out of. the headrace above *e lining- into the surrounding country Ind working round into the drainage iiyer, which, however, was quite sucteesfully coping with it. Of course, if -;he seepage increased, the tapacity of the drainage layer might lot be adequate. As far as could be ascertained, the <auee of the trouble, said Mr. Furkert, vae a leakage tihat had developed within i few yards of the eastern side of the mt-off wall, between the head of the Cornell lining and the traffic bridge.

The main problem facing the engineers vas to locate the actual spot, with the 'olume of water in the headrace. Naturtlly, with an undertaking that was •arning about £500 a day there was no tesire to. stop the machinery. If the icadrace were de-watered the defect •ould be found easily, but the emptying if the headrace was not contemplated. So far the surplus water in the head.'ace had been lowered by approximately "our feet, and this .process would continue in fiie 'meantime. Mr.. Furkert ■ntimated that; it would be possible to Jower the level of water .by. 15 feet vithotit' stopping the electric generators, is. sufficient water would still be flowing Ihrough the penstock- intakes.

"Outlook Quite Satisfactory." "We have a fair, idea as to where the frouble lies," continued the engineer. 'We have had a water diviner on; the ;bb, in. addition to divers, and the indications we :haye received have enabled ue 'o sink ashaft onthe upper side of the •ut-off wall on. the assumed line of lnfil-',ration.-When wehave. tapped the. origin if the leakage, it will, txs plugged. Al;hough."the taek is a difficult one, the ictual plugging,'once the'faiilt is located, ■an :be done without de-watering the headrace. The outlook is quite satisfactory. The ..drainage system has worked almost perfectly and has exceeded expectations."

The •attention of Mr. .Furkert was Irawn to a rumour that the eecond tur■iine at the powerhouse had given cause ior concern, on account of the development of' vibration. Mr. Furkert said there was nothing in the suggestion. He lad heard nothing of any such happening.