MANGAHAO HYDRO PROGRESS.

Shannon News, 13 June 1924, Page 3

MANGAHAO HYDRO PROGRESS.

YAM 1 bUUiE (JHAMBER DESCRIBED POWLIi HOLfeL APPROACHES COMPEL! lON. ONE GLNLRAIOR IN PObITIO.N. Mucn iids seen wntten in the newspapers about tue stupendous work mat is ocrng carried put m connection with Uie construction of the tMaUgafiao hydro works, the main points oi public Interest being the huge Power'House.

anu" the massive Arapeti and Mangahao Dams. Little.is .hoard 01 the con- ■ jjtruetion oi the Surge Cliamber, no doubt owing to this, work being off the beaten track and from the vj/itois point of -view most difficult to reach. Access necessitates a 900-foot climb from, the Power House, that is unless a person is fortunate enough to secure a -Uft up in the truck which is used ior conveying material to tiie work. On Wednesday a representative of the "Shannon News" paid a- visit, to trie: Chamber, being s hown over by .VI i .J T. .Stevenson, who is' construction foreman* of the work and Mr Gagli- , ardi. The pressman saw something unexpected and was deeply impressed by the engineering difficulties that have been overcome in the construe-1 tion of the chamber, especially so when it has to be remembered that, 10 -enable the work to-be carried b'u't! n'.il the material had to ■ be/ named 'JOO .feet up the steep incline, Bv west means 8000 tons of material have been iKjuveyt'd to the, work to date - THE CHAMBER'S FUNCTION.

Thu huge chamber, Avhich is of *i funnel shape, is practically completed so far as the concreting is concerned, Urn llnishing touches now ueing put .on. When completed it wUI have a. railing erected around the tap. A spill-way has been constructed to early any surplus water to a.'gully nearby. The chamber is the connecting link between the tunnel from Arapeu and the pipe-iiire wh-ich..' goes down the face oi the hill to the powei house. Its particular function corner into -operation when, at any time, u becomes n'ecessary to shut off the water at the power house. This would cause the head of water to surge back into the Chamber momentarily ami at this moment tiie chamber will'carry its normal quantity of water, which will be about 10ft from the top THE CONSTRUCTION WORK

' In the ■construction" of the Chamber approximately 7000 yards of metal 'had to be removed during the excavating, while 1500 yards of,concrete was used together with 90 tons of steel reinforcements. In the centre of the chamber is a, 100-foot IrHsley hoist which is used for hauling purposes in connection with, the work, while there is also a cantilever for the -winches for lowering the screens adjoining, which are two shafts leading to the base of the chamber. At 'tie end, of each there will be two gates each, weighing two tons 12tewt., which are prima rilv used -in/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 lectin length, in sft sections and 4ft 7in in width are to be put in to prevent debris coming through'to the powerhouse, and tbev will be so arranged that should one get Mocked the water -will flow over the tap. IMPRESSIVE DIMENSIONS.

The Chamber, which is built at an angle or 29 .degrees, is TBfi in diameter at the bottom extending out to 85 feet, in diameter at the top with a depth of 76 feet. To the layman it gives the impression' of befing a very

fine pielce of work, reflecting* great \ credit, on those responsible for its con- ' struction. All the material for the work had to bo conveyed up the incline to the site by a truck which takes 20 minutes t,o 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' ikg concrete undertaking was convoyed up in two 36 gallon barrels. A visit was also m'ade in the electriic 'motor, in company with u\lr Gagliardi to No. 1 iadit about 20 chains along the Arapeti tunnel, where there is a. big dump of metal that was removed from the tunuel during its construction. This is now being trucked to the icrusher outside the surge chamber and alter ibeing crushed ,is taken/ through the tunnel to, Arapeti to be used in the daim. Quite a big traflic, in .cement, is being carried on from the surge chamber right-through to (Mangahao. it is much cheaper u. convey 'material from Shannon by this route to Mangahao, the cost working out at approximately .las per ton us against 3-is M per ton by road. THE-Pllli Urn-..

, The contractors lor.laying the pipe line are well forward with their work und there is only the connecting up to be finished and aproximately three diaius of pipes to he lu;id where at the present moment .tlie hiauliiig ma, chinery 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 first of huge generators, which weighs Zb tons, was placed into working position. A travelling crane which is erected hi the Power House was used for handling it, which made easy work of it. The placing of the huge.piece of machinery into working pwsi'tion was carried out under the supervision of Mr Broad, representative of the contractors, Messrs Vickers, Ltd. Aerials on the Poavit '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'polishing up the large number of windows.