WAITAKI DAM.

Press, Volume LXVI, Issue 19928, 15 May 1930, Page 16

WAITAKI DAM.

CITY COUNCILLORS* VISIT. RAPID PROGRESS WITH WORK. (CiICIAL TO ".HE r-BESS OAMAEU, May 14. Owing to the steady increase in the consumption of electricity in Christchurch and the fact . that tho Lake Coleridge station is now up to the limit of it 3 capacity, the progress of the work at the Waitaki dam is of great moment to Christchurch. With a view to securing lirst-hand information on the propress being made at the Waitaki dam a party of Christchurch City Councillors, comprising Crs. H. T. J. Thacker (chairman of the Electricity Committee), Annie I. Fraer, and J. W. Beanland, together with Mr J. S. Neville (Town Clerk), Mr A. E. Galbraitk (City Engineer), Mr E. Hitcheoek (General Manager, Electricity Department), and Mr J. C, Forsyth (City Electrical Engineer), made a visit of inspection to the Waitaki works to-day. They arrived late this afternoon, and were met on arrival by the engineer-ih-chargc, Mr K, H. Packwood. The party was taken by Mr Packwood over 'die various places of interest at the works. Mr Packwood outlined the salient features of the dam to the visitors pointing out that at present 800 men were engaged on the work, which was going on night and day with three shifts, but as the work further progressed, the way would bo open for engaging further labour >vith a maximum of 900 men. He gave the visitors the reassuring news that the work was right up to date, and, barring unforeseen tremendous Hoods, power would be delivered in 22 months. j Mr Packwood first pointed out the excavations for the power house, which would contain 40,000 cubic yards of concrete, or two and a' half times the amount in the biggest power house built in New Zealand. Provision is being made for the installation of five 23,000 h.p. turbines. The dam would contain 150,000 cubic yards of concrete, of which 110,000 would be below the water level of the river. Oho great advantage of the Waitaki compared with the Waimakariri was that the lakes feeding, the river, Lakes Ohau, Tckapo, and Pukaki, acted as storage, and regulated the iiow .of the river, maintaining an even flow. It was explained that at present the river was confined to half its width, and the coffer-dam was now being excavated for a• section of tho dam on the Canterbury side, in which eleven or twelve sluices would be made, with a capacity to take tho river's winter flow. Next winter the Otago half of the river would bo shut off by.a coffer-dam, and the river directed through the sluices. No system could be devised to enable them to do the work in less than three clear winters. If excessive floods occurred, water would rise over the top of the coffer-dam and send the lot down the river. . That would be an extraordinary circumstance, but nothing else could be doae" to cope with it. Mr Packwood pointed out that though sites narrower in width might have been found, it was necessary to have a site with three features: — (1) To "give a spillway 1200 feet in length. (2) To,give, space 360 feet in length for power-house. (3) A site for excavations to return the water to the river at a satisfactory level. The rock for the foundations is not particularly hard, but it is satisfactory for the purpose, and hard enough to take the weight of the dam bearing on it. In reply to Cr. Thacker, Professor Packwood stated that when tho rock bottom in the first coffer-dam was reached, no trace of gold or minerals was found, but in the excavations in the hillside on the Canterbury side of the .river moa bones had been found. [ Since the completion of the driving of the. steel sheeting of the coffer-dam, the water., had been lowered 12 feet below the river level, 'and work was proceeding; apace in an attempt to reach rockbottom by the end of Jiine. Dressing roek for the foundations would occupy a month, and it would be necessary to have the concrete for the dam in place before summer. The dam would rise to a height of 110 feet from the rock bottom, and would be 105 feet through at the base, which would. vary according to the depth of rock. The reason for tackling the central portion of the dam first, which was now completed, was to make possible tho installation of plant- to deal with the large coffer-dam on each side in turn. Dealing with the formation of a iako by' tho dam, Mr Packwood explained that there was no possibility of the lake level falling too low, as the river was fed by three lakes, which in turn were fed by snow waters from the mountains. The possibility of a flood sufficiently high to endanger the works was very Temote, as observations of the river levels precluded the possibility ,of any such flood. After the inspection, had been completed, Cr.. Thacker expressed the opinion that it was very doubtful if power could be delivered in 1932. Ho thought it would take till 1936 to complete the work. Ho said that a tremendous amount of work had been done, since his yisit three months ago. Further, Cr. Thacker expressed uneasiness on the question of floods, and ventured the. opinion that landslides on the steep hills on the Canterbury side, that would block the sluices in the dam, might not bo a remote possibility. Cr. Beanland said it was a wonder ful scheme, and the possibilities were that when it was completed the power available would make a vast difference, , not only to Otago, but also ■ tc Canterbury, and would link up the whole country from Dunedin to North Canterbury. The methods adopted by the engineer were very thorough, and the whole works were so interesting that he would like to spend days there. He was sure that every effort was being made, to expedite the work. It. seemed to him improbable that the dam would be completed in 1932. If they were going to have luck for everything to. go right, then it • would be nothing short of marvellous. They in Christchurch. were particularly interested, much more so than the.residents of Otago, because Lake Coleridge was getting Up to its limit and they must have more power in Christchurch by 1933. That was definite, and if they did not -get more power by then they would bo up against it. That was one of the chief reasons for the visit that day, so that. they could impress the Government with the urgent need for augmenting the Lake Coleridge supply, which now served. South Canterbury and North Otago. • The party remained overnight at Kurow, the intention being to pay another visit in the morning before returning north.