FORMER SCHEME RECALLED

Press, Volume LXXIV, Issue 22430, 17 June 1938, Page 15

FORMER SCHEME RECALLED

Tunnel From Lake * To Opihi River \ RECENT INVESTIGATION BY DEPARTMENT [From Our Own Reporter.] KUROW, June 16. Unlimited electric power is being, dissipated through the exceptional summer flows of Lakes Tekapo, Ohau, and Pukaki being unharnessed. Although schemes for their develops ment have been advanced at various times, Tekapo has been considered to afford the simplest construction, and two plans for works obtaining their water from this lake have been investigated recently by the electrical branch of the Public Works Department, and the water storage now proposed for Waitaki could, in the opinion of the department, be equally appropriate for the development of a big scheme on the Opihi river. However, the cost of such a large undertaking is not considered to be warranted, unless a ready demand for power were available. . , t Surveys have been made in the iasi two yeafs for the taking of water by a tunnel through the Two Thumb range to the Opihi river, and another tunnel project investigated was to through the hill o*l T i Pukaki side of Tekapo House locate the power-house m the gorge at the Vst bend in the river below its outlet e, s «fo^ly of these schemes is being considered just now; but it is pos> sible that a smaller power scheme might be embodied in. the dam to raise the lake level to s tore water for use at Kurow. One scheme d WnedJ>y Mr Bovine, a celebrated hydro-electric engineer, was to make an open cut instead of a tunnel through to the river gorge, and allowed at initial stages for 12.000 kilowatts from alow head, and the ultimate development of 20,000 kilowatts. This proposal was adopted for a determined effort to develop power from Lake Tekapo, ind_pendently of the Government, which was made in 1920 by South Canterbury. A licence was virtually granted on condition that the district formed itself into a power board • area. The board was formed; but the succeeding Public Works administration threw cold water on the project ofdistrict development, as apart from State envelopment. Public opinion changed, and with the promise by the Government of an early start on the power scheme near Kurow, which would supply all power required by South canterbury. the Tekapo scheme was dropped, The argument which probably carried greatest weight in causing the Tekapo project to be dropped was the advancement of fear for the safety mid stability of the supply: because a big transmission line would have to traverse nearly 25 miles of country subject to heavy snowfalls. The Opihi Scheme The Opihi scheme recently -investigated by the department has been only vaguely mentioned in official reports, yet its outline bears close resemblance to the proposal made by Mr P. S. Hay, Chief Engineer of the Public Works Department in 1906, when reporting on possible hydro-electric development throughout the colony. “The best scheme for utilising all the flow, from Tekapo. if ever it is desired to do , so, would be to drive one or more tunnels from the lake towards Silverstream, and from the end of the tunnel take water in pipes to the level of the Opihi,” he reported. “About nine and a half miles of tunnel would be required, and the length of continuous tunnel would be about seven and a quarter miles. The pipe line would apparently be from one and three-quarter miles to two miles long. The fall obtainable would be from 850 feet to 900 feet, and the power would be 400,000 horse-power for continuous work, say 800,000 horse-power for 12 hours a day. The lake would be dammed to store water to the maximum possible height, perhaps 50 feet.” A feature of such a scheme in the Opihi as propounded by Mr Hay, and more recently studied by the department. is that after use at the station, and discharge into the Opihi, the water could be used again further down if further power supplies were needed. Mr Hay scouted any objections to the Silverstream scheme from the largely increased flow in the Opihi. maintaining that the objections would not hold in view of the advantages to be gained.