THE WAITAKI DAM

Press, Volume LXX, Issue 21256, 30 August 1934, Page 4 (Supplement)

THE WAITAKI DAM

A Great Engineering Work

Imagine a wail of solid concrete as high as the roof of the Cathedral, starting at the corner of Gloucester street and Colombo street, running along Colombo street, across the Square and down almost to Cashel street, and you will have some idea of the size of the Waitaki Dam, which in a few weeks will be storing millions of gallons of water in the Waitaki river to generate electricity for Canterbury and Otago. This enormous dam, which has taken five years to build, runs from side to side of the Waitaki river in a narrow gorge among the hills. One end of it is in Canterbury and the other in Otago, since the river is the dividing line between the two provinces. When it is finished, the water piled up behind it will form a lake of 2200 acres, or more than

penstocks, rush down steep tunnels and flow into the turbines, which are built right at the bottom of the dam. So great will be the force of the flow of water that eventually it will be able to generate nearly three times as much power as the Lake Coleridge power station. To begin with only two turbines and generators are being put in, and these alone will generate more electricity than Lake Coleridge, and three more turbines and generators will be added later as they become necessary. If you were to cut a section downwards through the dam and look at it sideways, you would see that it was shaped like a triangle, being very wide at the bottom and quite narrow at the top. The dam is made in this shape for two reasons. First of all, if it were only an ordinary

five times the size of Hagley Park, and the surface of this lake will be nearly 100 feet above the level of the river. . When water falls from a height it gains immense force, and if it can be directed into the blades of a turbine connected to an electric generator, it can be made to produce a huge quantity of electric power to light houses and cook meals, and do all the other wonderful things that electricity does for us. The purpose of the dam in the Waitaki is to raise the level of the water flowing in the river, store it in the lake and provide a means of guiding it into the turbines so that it can perfofm useful work for the people of more than half the South Island. The finishing touches are now being put to this great engineering work, and in a few weeks it will be in operation. From the ; top of the lake the water will pour through huge openings cut In the side of the dam, calleai

wall the same thickness all the way down there would be a danger of its toppling over because of the pressure of the waters of the lake above it. Secondly, when the lake is full, all the water that is not used in the turbines will flow over the top of the dam back into the soft, shingly riverbed. If it were allowed to fall straight down it would dig away the bottom of the river and end by undermining the whole dam, but with the triangle-shaped dam the water will flow out along the sloping side and so be guided comparatively gently back into the riverbed. When the dam is finished and all the work of testing the electrical gear completed, the Waitaki power station will be linked up with Lake Coleridge and with the station which supplies power to Dunedin. All three stations will then work together and when you switch on the light

it is just as likely that you will be using electricity made at Waitaki as at Lake Coleridge, whence Christchurch gets its power at present. When that day comes one of the greatest engineering feats ever attempted in New Zealand will have been completed, and the South Island will be assured of an adequate supply of power for many years to come, —L.W.P.R,