GREATER TUAI

Gisborne Herald, Volume LXVI, Issue 19999, 26 July 1939, Page 4

GREATER TUAI

LOWER DEVELOPMENT HYDRO-POWER SCHEME TUN X E Ll/IX'G <>L E RATIO X' tt A<V<VMMODATION FILLING (Special to the Herald.) WAIROA, this day. Good progress is being made with the preliminary work in connection with the Waikaremoana hydro-electric development scheme and the area about Tuai at present is the scene of great activity. With every week more and more men are arriving and as fast as accommodation can be provided it is being taken up.

With the arrival of more men it has been found necessary to provide greater facilities at Tuai and one of the improvements at present being carried out takes the form of a new hall and theatre to replace the corrugated iron building which has served this purpose until now. Already good progress has been made with the erection oC the building by the contractor. Mr. W. Iledley, Wairoa. The hall Will be approximately *l3 ft. in length and the cost is in the vicinity of .£3OOO. In addition, extensive alterations aie to be made to the school to provide accommodation for the anticipated large increase in the roll numbers, while other work at the settlement provides for the erection of an add : - tional six garages for the Public Works Department. £1,000,000 Extension Plan

Costing in the vicinity of £1.000,000, the lower development scheme is one which offers many engineering problems. The work so far, of course, has been more or less of a preliminary nature, the immediate concern being the establishment of the camps in which the large number of men who will be engaged on the scheme will be accommodated.

Present indications are that once the scheme proper has been got under way no great difficulties will be experienced. Tunnelling operations have not yet commenced, but everything is just about ready to make a start on this task. A large gang of tunnellers is expected to arrive on the job Within a short time. The new power-house, which will be nearly two miles down the valley from Tuai, will be operated by water which flows through the penstocks at the present plant, and it is stated that conditions generally are probably unsurpassed in the Dominion for the generation of electric power from natural sources. Exhaustive Preliminary Plan The additional plant is required to cope with anticipated power shortages' in the future, and it was after a most exhaustive survey, during which hundreds of bores were sunk to test the foundations at various points, that the lower development scheme was instituted.

At present the capacity of the Tuai plant is 40.000 kilowatts, and the new turbine which is now being installed will produce an emergency power ration of 20,000' kilowatts at the existing station. The new power-house at the lower development site will provide a further 40,000 kilowatts. The construction of the complete new generating scheme below the existing power station entails the creation of an artificial lake lormed from the water from the present station, augmented from the Waikarotaheke 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.

From the intake at the extreme end of the lake, the water is to be conveyed through a 16-ft. concrete-lined tunnel to the surge chamber, which will be about 9600 ft. away. 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 surge chamber will be situated on a spur overlooking the powerhouse and from it the water will spill down twin 7ift. 6in. pipes to the powerhouse, a drop of 360 ft. The two 280' h.p. vertical turbines will provide the generating power.