IMPORTANT STAGE

Gisborne Herald, Volume LXVI, Issue 20086, 4 November 1939, Page 4

IMPORTANT STAGE

TUAI POWER SCHEME

LOWER DEVELOPMENT

CONSTRUCTION 1N PROGRESS

PRELIMINARY WORK DONE

(Special to tie Heralil.) WAIROA, this dav

After almost 1C months the preliminary work on the lower development hydro-electric scheme at Waikaremoana, estimated originally to cost in the vicinity of £1,000,000, is merging into construction and the area about Tuai at present is the scene of great activity.

The scheme was first mooted in July, 1937. and a year later, after a most exhaustive survey, during which hundreds of bores were sunk to test the foundations at various points, a start was made on the work. During the past l(j months the work has been mainly of a preliminary nature, one immediate concern being the establishment of the camps in which the large number of men who are engaged on the scheme are accommodated. A total of 120 married men’s quarters and 220 huts have been erected on the new scheme, together with offices and complete workshops.

Before the actual construction work could commence five and a half miles of reading had to be built, on which was deposited 12.000 cub. yds. ol metal, and in one section a huge cliff had to be blasted and a road carried round the face of the slope. A further example of the nature of the preliminary work is the fact that the bed of a creek had to be lowered so as to allow the water to flow through a 10ft. concrete-lined tunnel, 9800 ft. in length, to the surge chamber. Further Facilities Provided At present there are 280 men engaged on the lower development scheme, and with the arrival of the men it was found necessary to provide greater facilities at Tuai. A new hall and theatre to replace the corrugated iron building which lias served this purpose until now has been erected. The ball is approximately 113 ft. in length and the cost was in the vicinity of £3OOO. Work on the new two-roomed school, to provide accommodation for 70 children, is almost completed. An indication of the growth of Tuai as a result of the institution of the new scheme can be gained from the fact that 80 children are attending school at the township itself and 68 at Firipaua camp.

Further preliminary work was the erection of an additional six garages tor the Public Works Department. The construction of the complete new generating scheme below the existing power station entails the creation of an artificial lake formed from the water from the present station, augmented from the Waikaretaheke River, which will be brought through a canal. The lake will be about 80 acres In extent and its formation will require the shifting of recreational grounds and buildings now situated on the lake site. Huge Tunnel

From the intake at the extreme end of the lake, the water is to be conveyed through the huge tunnel which will be 9800 ft. in length. To pass under a swamp at the intake end of the tunnel it will be necessary to construct an inverted syphon which at the lowest point will be 150 ft. below the tunnel levels at either side. The fabrication of the inverted syphon is one of the most difficult tasks to be faced on the scheme, and when completed this work will be one of the largest of Its type in the world. At present work has reached almost a half-way stage on the construction of an 11,000 ft. long drainage adit which will be used to drain the syphon. One of the most difficult and important jobs in connection with' the scheme is the construction of the concrete-lined tunnel which is to convey the water from the intake at the extreme end of the artificial lake to the surge chamber. Huge movable steel frame-works, 16ft. in diameter and weighing 20 tons, have arrived at Tuai from Wellington for use on the tunnelling operations. These frame-works act as a mould and fit round the tunnel, concrete then being poured on them. By an ingenious method a catch is then released and the frame-work falls apart ready to be shifted along to the next section. Three Shifts of Tunnellers There arc at present 90 men engaged in tunnelling operations and they are working in three shifts on two tunnel faces, but during the next fortnight, however, it is anticipated that work will be in progress on four tunnel faces.

Recently an important stage in the construction of the scheme was reached when the waters of the Waikaretaheke River were diverted into an artificial channel, thus making it possible for the carrying out of the excavation for the new power-house. Excellent progress has been made with this work, which has reached a stage where it will be necessary soon to blast the papa rock out in preparation for the erection of the new modern power-house. When the power-house is completed and the scheme is ready to be put into operation, the old river bed will be used as a tail race to carry water from the power-house back into the stream. Several permanent houses already have been erected for the engineering staff on a small rise overlooking the lower development scheme, and it is anticipated that the number of houses will be increased to 12, together with tiio erection of a modern hostel.