TROUBLE AT ARAPUNI

Sun (Auckland), Volume IV, Issue 994, 10 June 1930, Page 1

TROUBLE AT ARAPUNI

Spillway Weir Now Silent

LEAKS CAUSE MUCH CONCERN River Diverted to Old Course WHERE a few days ago swift waters curved gracefully over the spillway weir to foam at its foot as if in anger at the trick played by man upon them, now all is still. Below the weir lies a stretch of slimy pools in which fat trout stir furtively, trapped by the sudden diversion of the river into its old channel down the Arapuni Gorge. Arapuni presents startling contrasts. The overflow from the spillway weir which surged down in a series of tumbling rapids to crash and dissolve into misty spray over the Falls has ceased. But the gorge, which, except for brief intervals, has remained silent since eairly in 1928, is once again a roaring torrent.

At Arapuni township itself there was Considerable bustle. A Minister of the Crown had arrived post haste from Wellington. The chief of the Public Works Department, with his subsidiary officials, was on the joh. At Public Works headquarters motor-cars and messengers came and left at frequent intervals, Pressmen from as far afield as Wellington and Auckland were prominently in the foreground. Much oil was burned, and the wire fiom Arapuni was busy. The discovery of a two-inch crack in the concrete at the junction of the penstock intake and the spillway weir and cracks in the intake decking simultaneous with the discovery of leaks in the face of the gorge on the lower level, was the cause of concern. INVESTIGATION NECESSARY “It is almost certain that the headrace will have to be dewatered anrl Arapuni closed down for a while,” said Mr. F. W. Furkert, engineer in chief to the Public Works Department, late last evening. This is expected to take place on Wednesday. Late in the afternoon the Hon. W. B. Taverner. Minister of Public Works, accompanied by Mr. Furkert, Mr. C. J. McKenzie, assistant-chief engineer, Mr. I'. T. M. Kissell, chief electrical engineer, Dr. J. Henderson, Government geologist, Mr. T. MacLennan, district electrical engineer, and Mr. A. D. Dinnie, district engineer, Hawke’s Bay, who formerly was chief at Arapuni, returned from another inspection of the works. Shortly afterward the Minister and his staff left by motor to connect with the LinSted at Frankton. We are quite satisfied that the spillway weir itself is not In any danger, said Mr. Furkert. He referred to the fact that the comparatively thin, concrete apron beneath the spillway weir showed no effect of the earth subsidence that had occurred on the eastern side of the weir. He considered that this apron would have reflected any earth disturbance immediately connected with it. Questioned regarding the seepage, Mr. Furkert said it was sufficient to cause concern. The bottom of the headrace was a rock formation and he did not think that there would be any leakage there. It was possible that the water coming through might be from the two-inch crack at the end of the spillway weir, but that point could not be cleared up until the head-race was dewatered and a thorough examination made. Preventive measures were also discussed by Mr. Ferkert, who said that the cracks could either be filled up or the headrace lined with concrete. The dewatering of the headrace would provide the staff with an opportunity of proceeding with the work of concreting the bed of the river below the spillway weir from the falls up where considerable erosion which took place last August caused considerable concern at the time. Survey gangs were already carrying out preparation work in this connection yesterday afternoon. Asked about the hill under the outstation, through which the seepage is occurring, Mr. Furkert said it was of a sandy nature. WILL TUNNEL STAND? The measures at present being carried out at Arapuni depend a great deal on the ability of the diversion tunnel to carry out its task. When the erosion occurred below the spillway last year it was found necessary to divert the water in order to enable an examination of the bed to be made. Tile gates at the diversion tunnel were raised and in the short time that the tunnel was tried out it was found that to of the 900 one-inch bolts that fastened the steel lining to the concrete walls near the gates had been loosened in their sockets by the mighty force of the pent-up waters. Profiting by the recent trial the engineers welded the bolts to the steel casing and steel armour plates were also applied to the walls immediately below the big twin gates. It is here, it is thought, that the maximum stress occurs when the tunnel is used. Armstrong, Whitworth and Company realised that if the diversion tunnell was to be used as a by-pass in case of urgency, protection was needed and actually secured quotations of cost and submitted them to the department, but the recommendations A-ere ignored. The department, after realising the necessity of having the tunnel ia constant readiness for any emergency such as has arisen, had this suggestion carried into effet. In this connection it can now be said that the erosion scare of last year has served A useful purpose. “Of course, no one knows what is going on inside the tunnel,” said the Hon. V/. B. Taverner, when questioned regarding the ability of the tunnel to stand for any length of time against the extremely heavy pressure from the immense head of water behind the gates. Questioned on the same point, Mr. Pyrkert said that the tunnel had been strengthened. From the

experience of the recent trial run he thought it would well stand the strain. IN MILD FLOOD The gates were opened to two feet on Sunday afternoon and are being gradually opened as the level recedes. Yesterday the gates were raised to four feet and with that aperture 6,800 cubic feet of water a second was hurling Into the gorge. Late yesterday afternoon the engineers concluded their inspection with another visit to the dam, when they raised the gates another two feet, the six-foot opening releasing 10,000 cubic feet a second, this quantity giving the river the appearance of being in mild flood. Yesterday again saw a fair number of visitors at the works, but they were . not allowed to proceed any further than a little way beyond the dam at the south end, or past the bridge at the northern end. Prom these points nothing is to be seen except the fact that the gorge, whic-kr, except for the water coming through the turbines at the power-house, is usually empty, is once again a roaring torrent. For the time being the Taniwha of the gorge has come back into its own. Today the river swirls menacingly around the bulwarks of the power-house as if it would remove for ever this concrete reminder of man's mastery over nature. Today old Maori prophecies and dire warnings are being recalled, but the engineers of the Public Works Department go calmly on their way and with cheerful faith in the strength of their handiwork. SUPPLIES CURTAILED ENGINEER URGES ECONOMY ALLOCATIONS TO BOARDS J Trorn Our Own Correspondent HAMILTON, Monday. Owing to the closing down of the Arapuni power station, power supply boards will have to exercise strict economy. In a statement issued this evening, Mr. T. McLennan, district electrical engineer, Hamilton, said that a reduction of 15 per cent, would be made on Wednesday or Thursday in the amount of current available. The different sub-stations of the Public Works Department would inform the power boards as soon as the lime at which the reductions were required to be made was macfe known. He added that unless the load was reduced to the amount of power available the department would be compelled to reduce it either by lowering voltage or by cutting off power. The following are the allocations to which power authorities are required to reduce their supplies:—Hamilton lorough Council, 960 kw: Central Power Board, at Hamilton 700 kw, at Huntly 550 kw; Te Awamutu Board, f4okw; Cambridge Board, 570 kw; Waii:omo Board, 540 kw; Franklin Board, -i 280 kw; Waitemata Board, at Takapuna 1,170 kw, at Henderson 710 kw; 3ay of Plenty Board, at Edgecumbe 490 kw, at Waiotahi 520 kw; Thames Valley Board, at Matamata 1,170 kw, Waihou l.lOOkw, Waikino 500 kw, Herepeehi 700 kw. LOAD EXPECTATIONS KINGS WHARF STATION PREPARED BOARD'S WATCHFULNESS King's Wharf pcvwer station will probably take over Arapuni’s load in the City tomorrow morning. The Auckland Electric-Power Board has made full preparations to effect the change-over when Arapuni closes, but it is fully cognisant of the strain which will be put on power resources. The general manager of the board, Mr. K. H. Bartley, expects the King’s Wharf station to carry the demand by straining to the utmost. The great difficulty is in running the plant under overload, for the slightest fault will mean a failure, in all probability. Coal supplies are already being built up to run the lvingr’s Wharf plant. There are sufficient supplies at the moment to run the plant for three or four weeks, although contracts had been allowed to expire because the plant was no longer in use. Until one of the three generators was closed on May 22, the Auckland Board was being supplied with 2t>,000 kilowatts. Since the generator was shut down the supply has been 2&.000 kilowatts. King’s Wharf will maximum of 29,000 kilowatts. The total power available from the inssources is estimated by Mr. Bartley to be 46.200 kilowatts, assuming that ITorahora will yield 12,00 kilowatts. It had now been learned that 10,500 kilowatts, and only 8,000 at first, would come from Horahora. CContinued on page 10#) .