ELECTRIC POWER

Timaru Herald, Volume CLVI, Issue 22935, 4 July 1944, Page 4

ELECTRIC POWER

Tekapo Inspected By Minister Resumption Of Work Soon jaU'— -... The Hon. R. Semple, Minister of Public Works, in company with two engineers of the Public'Works Department, yesterday inspected the preliminary work being done at Lake Tekapo in preparation for the resumption of the construction of the hydro-electric scheme there. According to the Minister's secretary, Mr J. W. Nissen, Mr Semple expressed satisfaction with the progress made in the building accommodation for the men who will start work there in the near future. Highbank Scheme The Highbank hydro-electric scheme was nearing completion, said Mr Nissen. A machine or part of a machine which had been lost in transit by enemy action had now been replaced, and it should not take more than six months to install it. By that time it was expected that the race would be ready and water from the Rangitata and Rakaia Rivers would be available for the driving of the single turbine which would develop 25,000 k.v.a. When this was completed labour and material would be available for the resumption of work at Tekapo. The scheme there had been discontinued a few years ago because of the Army’s need for huts and manpower. Method of Tunnelling The method by which the tunnel is to be constructed is described as new to New Zealand. Although it has been followed in Europe and in the United States for a number of years. The method was suggested by the geological nature of the country which is of morainic shingle. The tunnellers will work inside a giant steel cylinder, which is nearing completion at the P.W.D. workshops at Temuka. The shields are fundamentally steel cylinders containing platforms on which the miners will work. As the faces are excavated the shield will be forced forward by means of hydraulic jacks. Twenty-five jacks, with a total thrust of 2500 tons, will be used. Pre-cast reinforced concrete blocks, as the shield moves forward, will be carried into the chamber on railway trucks, swung into position by machinery and bolted together to make a circular compression lining for the tunnel. Thirteen blocks, each 3ft long and 14in thick and weighing 10001 b, will go to the circumference of the tunnel, which will be 20ft 4in internal diameter.