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In order to demolish the old head-race wall built by the Waihi Company the station was shut down during the Easter holidays. Pneumatic drills were operated over the whole face of the wall, which was then blasted in layers, the disposal of the spoil being effected by the use of power-driven excavators and trucks, together with a barge ; 450 cubic; yards of concrete were removed in this manner. Another portion of the work which requires careful handling is the deepening of the old tail-race. The bottom of this tail-race, which consists of volcanic tuffs, requires to be broken up before it can be handled by dredging. Tho method adopted is to drill holes by pneumatic drills, operating through stand-pipes, at an average depth of 12 ft. below water-level ; the holes are then loaded through these stand-pipes and fired electrically. So far an area of 650 square yards has been dealt with. In order to handle tho blasted material from this excavation, a eableway drag-line excavator is to be used for dredging the 8.500 cubic yards of spoil. This drag-line has a maximum range of 700 ft. The erection of the machine is practically complete, and a start with the actual excavation will be made almost immediately. The new bay of the transformer-house has been started, and irrinor alterations to the workshop carried out. A considerable amount of investigation work has been carried out to enable a suitable site for the permanent weir to be located. An examination discloses unsuitable foundations at some of tho earlior-selectod sites, but the fine of the weir has now been definitely fixed, and a comprehensive plan of the layout has been prepared. Two permanent-stall' cottages have been built, and various temporary and maintenance, works have been attended to. Mangahao. Very substantial progress has been made with the construction of these works during the past year. The most difficult portion was the construction of the lower Mangahao dam. In order to enable the foundations of this dam to be put in, two separate methods of construction had to be followed. One half of the dam is an earthen dam with a concrete core wall. This core wall had to be carried down some 70 ft., and the excavation required very substantial and carefully placed timbering in order that the material in place, which was to act as tho major part of the dam, might not be in any way disturbed, and more particularly in order that the large number of men working in the confined spaces below might not bo injured by falling stones or other substances. This work, though tedious and extensive, presented no unusual difficulties. The other half of the dam, however, Irad to be built of solid concrete, and founded in a narrow gorge in which the water was from 12 ft. to 14 ft. deep at normal times, and might be twice that in less than half an hour if heavy rain fell in the hills. The first operation was to divert the liver by means of a by-pass tunnel, and construct elaborate coffer-dams to lay bare the site of the foundation. A heavy crib log pile and concrete dam was first required to divert the river through the by-pass tunnel; secondly, two double rows of steel sheet piling, filled with stones, clay, and concrete, were built, one above and one below, and heavy pumps were installed in duplicate to prevent interruption ; and finally, when the site had been punned dry and excavation had progressed considerably, a watertight reinforced-concrete temporary dam, both above and. below the permanent work inside the main coffer-dam, had to be built. The work was inundated by floods repeatedly, often with hardly any warning, so that men sometimes barely escaped with their lives ; but, although these floods caused considerable delay, the detail arrangements for removal and securing of men and material were so successful that practically no plant or temporary work was lost. Every opportunity was taken when circumstances were favourable, and work was carried out night and day by means of three shifts. In order to prevent an undue rise of the flood-waters as tho work progressed, which would have resulted in flooding the No. I tunnel, and also to enable aggregate for concrete to be obtained from the river-bed, a gap 40 ft. wide was left in the main portion of the dam as soon as the foundations were brought up to ordinary water-level. This gap will be filled in after the gates have been placed in position. The gates for the by-pass tunnel and for inlet No. 1 tunnel are now being placed in position. Great trouble has arisen from the non-arrival of these gates, the contract for which was let long before the excavation started. The total quantity of concrete in this dam will be 21,827 cubic yards, and of this amount 16,019 cubic yards had been placed at the end of the period. The last 3,000 yards will be complicated icinforced-concrete work in connection with the automatic regulating-gates ; but, quite apart from the construction of this portion of the regulating-gates, water can be diverted to the power-house and the same put into commission. The Tokomaru dam is nearing completion. The excavations of the foundations were carried out in the early part of the year, and since then 18,698 cubic yards have been placed out of a total quantity of 21,800. As there were no deposits of shingle or stone adjacent to the work, all the stone for the concrete had to be quarried and crushed, and the sand made by pulverizing the quarried rock with special machines. The tunnels connecting the two dams, carrying on from the Tokomaru dam to the surge-chamber, which were driven last year, have been lined throughout, and only the closingup of adits, fitting of gates, and grouting of packing requires to be done. There will be no difficulty in diverting water to the power-house as soon as works there and beyond are ready. The surgechamber is practically complete, and only requires the erection of gates and screens, which are on the ground. The pipe-lines have been practically completed, with the exception of the 72-in.-diameter pipes between No. 1 anchor block and the entrance to the tunnels leading to the surge-chamber. The pipes themselves are all on the site, and have been riveted up in long lengths in order to facilitate their final placing, which will be proceeded with as soon as the crushing and concrete-mixing plant, which is located at this spot, is finished with and removed.

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