Gigantic Missfire

Sun (Auckland), Volume I, Issue 203, 16 November 1927, Page 8

Gigantic Missfire

ARAPUNI IN INSTALMENTS Difficulties at Powerhouse Site AFTER the lowering of the river on Sunday the ArmstrougWhitworth engineers at Arapuni are more convinced than ever that they were right in declining to build the powerhouse according to the specifications in their contract. They say that the condition of the river-bed confirms their estimate of the composition of the foundation. Accordingly the powerhouse site will remain empty unwil an agreement is reached with the Government.

POR eighteen months no construex tive advance has been made with the powerhouse. Its history in that period has been a history of tests and experiments that, according to the contractors, failed to reveal a foundation sound enough to justify a start on construction work. Every development since the site was excavated has strengthened their conviction that to proceed as directed would have been fatal. The right and wrong of Armstrong, Whitworth, Ltd.’s attitude may have to be determined by arbitration or in the law courts, and in the meantime

the taxpayer can only conclude that a grievous blunder was committed by. those responsible for the delay in reaching an arrangement. For at least’ a year the powerhouse deadlock appears to have been an endurance test, with the contractors at one end and the Government at the other. Each side had its colours nailed to the mast, and the result is the present tragic situation, a giant hydro-electric scheme brought in one section to an apparently successful climax, and in the other not even begun. The taxpaying layman can judge things only as he sees them. In this case the faculties of observation return a sufficiently startling verdict. To the dam, outdoor transmitting station, headrace and spillway the final touches are being applied. But for a few yards of concrete in one corner of the dam, and the fixing of “muck-screens” in front of the penstock entrances, the Waikato could be sent rolling down the headrace, and so into the penstock tunnels, sloping to the powerhouse. But at the powerhouse site there is nothing. A great segment has been bitten from the cliff, at the foot of which yawn the mouths of penstock tunnels. Were development up to time, the process of linking the tunnels to the turbines would now be under way. But the turbines are a mile away, still dis-

jointed, beside the road to the township, and at least eighteen months must elapse, with idleness dwelling upon the works already completed, before they can churn out power. Thus Arapuni, to date, is just a gigantic missfire.

Of the composition of the country at the powerhouse, the engineers on the job are positive. Since doubts first arose they have put down 40 or 50 test bores to various depths, and the results suggest no firm foundation, hut only massive boulders that have fallen from the cliffs in the course of centuries. Some of these huge rock masses were seen on Sunday in the exposed river bed. Others were encountered during excavation, and the rounded top of one is plainly visible on the outer edge of the site. In another place a wide rift, claimed to be characteristic, is plain for all to see. It was such a fault that caused a slab to topple, killing a workman, in the early stages of the job.

While they regard the bottom as unstable, the contractors consider the tuff wall at the back of the excavation to be sufficiently firm. Hence they have developed the proposal to separate the control station and powerhouse—one building in the original plan—shifting the control station some distance up the hillside, and moving the powerhouse back into the cliff. This, they consider, would solve the difficulty. PLANS OF POWERHOUSE

Briefly, the powerhouse plans provide for a building 200 feet long, 90 feet high and 90 feet wide. The control station, attached on the plan, is 28 feet wide, wedged between the powerhouse and the-cliffs.

Power will be produced by huge turbines lying flat, each of which will drive great motors mounted above on the same axle. Immense Johnston valves at the foot of each pipeline will govern the flow through the penstock tunnels, and the load on the turbines will be automatically adjusted by an ingenious vane arrangement admitting or excluding water, as required by the demand for power. When the water has helped to keep the wheels spinning it will be drained off in scientifically - constructed draught-tubes, perfectly streamlined so that no air will work back to the turbines, causing what the motorist knows as “knocking.” Other interesting features ara the petometer chambers, eerie vaults concealed in the cliff face. In these the velocity of the flow through the pipelines will be measured in long pressure tubes. Like the penstock tunnels and cabletunnel, which rise from the powerhouse site at a fearsome angle, the petometer chambers are already completed. Similarly the Swedish engineers of the A.S.E.A.. which is installing the switch-gear, have done most oi their work at the transmitting station, and will soon be waiting for the powerhouse and control station to be started.

No work whatever is at present being attempted on the powerhouse site, though pumps are controlling the water which seeps incessantly through the coffer dam on the river edge. Excavation for the turbine beds has to go 19ft below the present level, so there is a lot of water to be pumped yet before the Arapuni wheels start to turn.