WAITAKI SCHEME FORGING AHEAD.

Star (Christchurch), Issue 19070, 15 May 1930, Page 14

WAITAKI SCHEME FORGING AHEAD.

CITY COUNCIL PARTY ARRIVES AT AWAKING.

(Special to the “ Star.”) OAMARU, May* 14

In view of the possibility of the demands of the Lake Coleridge hydroelectric power station overtaxing its capacity* before the Waitaki scheme is completed, much interest is being evinced in the latter undertaking, particularly in Canterbury, which depends on Lake Coleridge for its sxipply. To-day, an official party from the Christchurch City Council paid a visit of inspection to Awakino for the purpose of gaining a first-hand knowledge of the undertaking and its possibilities. The party comprised Dr H. T. J. Thacker (chairman of the Electricity* Committee), Councillors Annie I. Fraer and J. W. Beanland, the Town Clerk (Mr J. S. Neville), the City Engineer (Mr A. R. Galbraith), the General Manager of the M.E.D. (Mr R. Hitchcock), and Mr J. C- Forsyth (City Electrical Engineer)- The trip, as far as Timaru, was made by train, from which place the journey Vv-as continued by motor. A halt wgs made at Waimate for lunch.

The inspection of works was reassuring, because it indicated that the work was going ahead throughout the twentyfour hours with the utmost number of men possible. Mr R. H. Packwood (Engineer in Charge) in the course of an exhaustive explanation of the work and its progress, stated that barring absolutely* unforeseen sunjmer or winter floods, power would be delivered in twenty-two months. The number of men employed totalled 800, but as expert work was proceeding, it would open the way for further labour, and a maximum of 900 men would be engaged. The visitors were greatly interested in the work on the coffer dam, which shuts off half the main stream on the Canterbury* side of the river. It was explained that there was a splendid rock bottom on which a permanent dam would be constructed. Both mechanical excavators and men were engaged throughout the twenty-four hours tearing out shingle which was of extraordinarily* fine quality, and highly suitable for making concrete. Mountains of screened shingle were piled up on the Otago bank in readiness to go through the mixers for return to the river-bed as concrete for the permanent dam. Mr Packwood said he expected to have half of the section finished by* the, end of June, when it would occupy a month cleaning out and squaring up the rock in the coffer dam. Sluiceways with gates would be constructed to allow the river a free passage, while the work proceeded on other sections of the dam. Work in the coffer dam at present is restricted to pumping out water and removing shingle. Engaged night and day* on this work is a Saurin excavator which occupies the attention of seven men. This machine, stated the engineer, is capable of doing the same amount of work as 50 men. However, the final work of cleaning out the coffer dam would be mainly by hand, owing to the exacting nature of the rock formation.

The excavations for the power house site on the Otago bank were inspected This work entails removing rock to a depth of 60 feet. The power house will then rise seventy* feet above the present ground level. Questioned by Dr Thacker, Mr Packwood said there was no possibility of the lake level falling too low as it would draw upon the Ohau, Tekapo and Pukaki lakes, which were fed from snow country round Mount Cook. The works would have 80 to 90 square miles of lake country to feed the dam. Mr Packwood explained that though there were many other places where the river could be spanned by a shorter dam the site chosen was favourable for three reasons—(l) It gave a spillway of 1200 feet; (2) There was room for a power house of not less than 360 ft, and (3) it was favourable to the return of the water to the river.

In reply to a further question the engineer replied that there was only* a remote possibility of the present work being carried away, which would be in the event of a tremendous flood or huge fault occurring in the rock strata. The prospects, however, had eliminated the latter possibility, and observations of the rise and fall of the river precluded any* flood sufficient to endanger the works. The rock being excavated, while not particularly hard, was satisfactory and would withstand any pressure required of it. The dam would contain 150,000 cubic y’ards of concrete, of which 110.000 would be below the water level. The river at present was discharging 45,000 gallons of water per minute. In flood time the water would reach a height of twelve feet above the spillway, being capable of discharging a million gallons per second. The party* is staying the night at Kurow, and last evening paid another visit to Awakino to view the works by r night. The camp is lit by* electricity* and from a distance has the appearance of a well lighted town. Huge floodlights enable the men on night shift to proceed with the work. Small engines puff about with loads of shingle and rock, the whole scene presenting an animated appearance which greatly interested the Christchurch visitors.