WAIPORI HEADWORKS.

Otago Daily Times, Issue 21147, 3 October 1930, Page 10

WAIPORI HEADWORKS.

POSSIBLE FATE OF NEW DAM. VISIT BY CITY COUNCIL. The Mayor (Mr R. S. Black) and Crs Shacklock, Scott, Wilkinson, Wilson, Bcgg, Campbell, Tapley, Mitchell, Marlow, and Lawrence, the town clerk (Mr Lewin), the city engineer (Mr Alexander), and the city electrical engineer (Mr Henderson) paid a visit to Waipori yesterday to have a look over the electric power works. As has been already published, the council has received an offer from the Government of power supply from Waitaki, and it is now considering whether it would be advisable, under the circumstances, to postpone the completion of the construction of the new HOft dam at Waipori. It was very satisfactory to see the effect of the recent increase in the height of the old dam from 43ft to 60ft. The wafer at the face of the dam was up to 54ft 9in, and there has never previously been such'a large quantity stored in Lake Mahinerangi. One inch of rain fell in the locality last week. Of course, if it is decided to continue the construction of the new 110 ft dam—which is 300 yards lower down the Waipori Gorge—the 60ft dam will be entirely submerged when the water rises above that height at the 110 ft dam. Naturally, the greatest interest was exhibited in the progress of the works at the 110 ft dam, and councillors will have the assistance of what they saw in helping them to come to a decision on the question of deferring or continuing the work of construction. It has alrpady been reported that the expenditure on the work is in the vicinity of £IOO,OOO, but this estimate must be considered as a conservative one. One small section of the dam is already completed up to its full height of 110 ft, and a very massive central section is built up to 60ft. The former section is what is termed a “gravity” construction. It abuts on the bank, and is built in a straight line. The latter section—in the centre of the river—is of “arch” construction. The position, therefore, is that the dam is to have a “gravity” 'section—a straight wall—-on to one bank, then the arch in the centre, and then a gravity section on to the other bank. There are at present 172 men engaged on the construction of the 110 ft dam, and they are working two shifts. The Mayor and councillors realise that they are faced with a very serious responsibility in being asked to defer the. construction of a dam which has already cost the city over £IOO,OOO of the estimated total cost of £220,000. Moreover, it may be found that at the end of the period of the contract for supply of power from Waitaki —assuming, of course, that the council finalises the tentative arrangement with the Government —the council may decide to enter into another agreement for power supply for a further period. If this position is arrived at it may with some confidence be stated that the “deferring” of the construction may become the “abandoning” of the work. At any rate, those councillors who were asked by our reporter to give an opinion on this aspect would not commit themselves to saying that the work would go on again at a future date. They even went so far as to admit that if the work were stopped and Waitaki power was always available it *was possible—one or two admitted more than possible—that the dam would remain unfinished. It should he explained that if Waitaki had not come into the picture there would have been no word against .the original intention to build the now dam to 110 ft, It should be further explained that it was only in May, 1928, that it was decided to start work at Waitaki. Had Waitaki power not been coming on the market, the City Council, in the face of the yearly growing demand for power, would have been forced to provide greater water storage at Waipori, and the construction of the 110 ft dam would have gone on without the slightest protest. The advent of Waitaki has completely changed the outlook. If the 110 ft dam is not completed then, of course, areas of land which would have been flooded under the original . proposals, and which were purchased by the council at compensation prices, will not be required. This particular land can, however, be used for the purposes for which it was previously utilised. Councillors say that the whole position must be viewed from the economic standpoint. The cost, of power from Waitaki, with the very great additional value of an insurance in the event of any breakdown at Waipori, on the one hand, aud the coat of the 110 ft dam, on the other hand, are the two ' material points to be considered. Possible revenue, future demands on power, water storage, capital expenditure, etc., are bound up with the calculations.- The executive officers of the council have been instructed to draw up reports on these vital questions, and then the City Council will come to its decision. No one will envy it its task. It may be added that there is a consensus of opinion amongst councillors that whatever happens the city will have to be linked up in some way with Waitaki as a stand by.