MANGAHAO HYDRO PROGRESS.

Manawatu Herald, Volume XLVI, Issue 2745, 14 June 1924, Page 2

MANGAHAO HYDRO PROGRESS.

VAST SURGE CHAMBER DESCRIBED.

POWER HOUSE APPROACHES COMPLETION. ONE GENERATOR IN POSITION. Much has been written in the newspapers about the stupendous work that is being earned out in connection with the construction of the Mangahao hydro works, the main points of public interest being the huge Power House and the massive Arapeti and Mangahao dams. Little is heard of the construction of the surge chamber, no doubt owing to this work being oil the beaten track and from the visitors point of view most diflieult to reach. Access necessitates a 900 foot climb from the power house, that is unless a person is fortunate enough to secure a lift nl? in the truck which is used for conveying material to the work.

On Wednesday a representative of the “Shannon News” paid a visit to the chamber, being shown over by Mr J. T. Stevenson, who is construction foreman of the work and Mr Gagliardi. The pressman saw something unexpected and was deeply impressed by the engineering difficulties that have been overcome in the construction of the chamber, especially so when it lias to be remembered that to enable the work to he carried out, all the material had to he hauled 900 feet up the steep incline. By these means 8,000 tons of material have been conveyed to the work to date. THE CHAMBER’S FUNCTION. The huge chamber, which is of a funnel shape, is practically completed so far as,the concreting is concerned, the finishing touches mow being put on. When completed it will have a railing erected around (lie top. A spill-way has been constructed to carry any surplus water ti> a gully nearby. The chamber is the connecting link between the tunnel from Arapeti and the pipe-line which goes down the lace of the hill to the power hoiise. Its particular function comes into operation when at any time, it becomes necessary to shut off the water at the power house. This would cause the head of water to surge back into the chamber momentarily and •it this moment the chamber will carry its normal quantity of water, which will he about .10 feet from the top.

IHE CONSTRUCTION WORK,

In the construction of the chaintier approximately 7,000 yards of metal'had to he removed during the excavating while 1,500 yards of e(iiierete was used together with 90 tens of steel reinforcements. In the centre of the chamber is ft 100 foot Tmslev hoist which is used for hauling purposes in connection with the work, while there is also a (antilever for the winches for toweling the screens adjoining, which

are two shafts leading to the base of the chamber. At the end of each there will be two gates each weighing two tons 12 cwts. which are primarily used is shutting off the water for cleaning out purposes or in the case of a break in the pipes, the work thereby being proceeded with without interfering with the flow. Two screens each 35 feet in length in 5 foot sections and 4 foot 7 inches in width are to be put in to prevent debris - coming through to tin- powerhouse, and they will be so arranged that should one get blocked the water will flow over the top. IMPRESSIVE DIMENSIONS. The chamber which is built at an angle of 29 degrees, is 18 feet in diameter at the bottom extending out to 85 feet in diameter at the top with a depth of 70 feet. To the layman it gives the impression of being a very line piece of work, rellecting great credit on those responsible for its construction. All the material for the work had to be conveyed up the incline to the site by a truck which takes 20 minutes to go up and 10 minutes to come down and could only take one ton of cement a .trip or one pipe. Everything from the smallest detail to the machinery for the crusher had to be taken by the truck. Even the water for the big concrete undertaking was conveyed up in two 30 gallon barrels. A visit was also made in the electric motor in company with Mr Gugliardi to No. 1 adit about. 20 chains along the Arapeti tunnel, where there is a big dump of metal (hat was removed from the tunnel during its construction. This is now being trucked to the crusher outside the surge elyuuber and after being crushed is taken through the tunnel to Arapeti to be used in the dam. Quite a big tratlio iu cement is being carried on from the .-urge chamber right through to Mangahao. It is much cheaper to convey material from Shannon by this route to Mangahao , the cost working out at approximately 15/per ton as against 32/ti per ton by road. THE LMI'E LINE. The contractors for laying the pipe line are well forward with their work and there is only the connecting up to be tmislied and aproximatel.v three chains of pipes to be laid where machinery is in operation for handling the material from No. 1 adit.

An important step towards the installation of the machinery at the Power House took place on Wednesday when lirst of huge generators which weighs 25 tons was placed into working position. A travelling crane which is erected in the Power House was used for hand-

ling it, which made easy work of it. The placing of the huge piece of machinery into working position was carried out under the supervision of Mr Broad, representative of the contractors, Messrs Vickers Ltd. Aerials on the Power House roof are now well in hand for connecting the power to main transmission line and the Power House, which is a very impressive structure, is now practically completed. Men are now engaged in polishing up the large number of windows.