MIGHTY RIVER HARNESSED TO THE SERVICES OF MANKIND

Timaru Herald, Volume CXXXVIII, Issue 19941, 27 October 1934, Page 5

MIGHTY RIVER HARNESSED TO THE SERVICES OF MANKIND

HAVING its source in the eternal snows on the towering peaks in. the Mount Cook region of the Southern Alps, something like 135 miles from the sea, the mighty hitherto untamed Waitaki River, confronted the engineers of the Public Works Department with a scheme full of difficult problems and yet invested in the immense potentialities as a source of hydro-electrical energy. The Source of the Waitaki

A chain of three lakes, which drain the ice-armoured slopes of the mighty mountains of the Southern Alps, pour their glacial waters into the turbulent Waitaki. Lake Tekapo, the largest of the three lakes, has an area of 580 square miles. Its deepest depth is 620 ft. and its height above sea level, 2323 ft. Tekapo has an approximate volume of discharge of 5000 cubic feet per second. Lake Pukaki is 31 square miles in area and has a discharge of 6000 cubic feet per second, and drains an area of 515 square miles, while Lake Ohau, which pours 5000 square feet of water per second into one of the principal tributories of the Waitaki, and drains an area of 444 square miles, has an area of 24 square miles. This chain of lakes is Gd from an unfailing source in the Alpine region, and this torrent of water, grown into a great stream to become the mighty Waitaki, moves majestically seaward, with at times a lordly dignity, and anon an almost overwhelming violence, to become one of the head rivers in the Dominion. Suddenly the river is forced into half its usual width by the imposing walls of concrete. Restless under man’s attempt to control this elemental force of nature, the waters of the Waitaki, with the urge of the eternal snows behind them, seek to escape the harness man attempts to

place upon their energy, and roaring wildly, and yet under control through the cramping walls, generate tremendous power, only to force their Way through the whirling turbines which exact from the waters enormous energy, and then foams it way to freedom once again.

The Giant Dam

But how has man contrived to curb this giant? A dam, which from abutment to abutment equals the distance from Ballantynes to the Bank of New Zealand corner ... a width of abutment wider than Stafford Street ... a height from top to toe nearly twice as high as Timaru’s new clock tower. A dam capable of producing sufficient power to carry the population of Timaru to the top of St. Mary’s tower every hour ... an amount of earthwork excavated, which, if loaded into single drays and placed end to end would reach from Timaru to Sydney . . an amount of concrete sufficient to construct an eighteen-foot main highway from Timaru to Christchurch

... a lake covering an area the size of the Borough of Timaru . . . turbines generating power equal to that of 150 express lomomotives. This is Waitaki —a modern miracle! Wataki dam is a gravity type, one of monolithic construction and has a crest height of 753 ft. above sea level. At the deepest section the total height from the end of the circle to the crest is 140 ft. and from this section the base width is 144 ft. The approximate water pressure per lineal foot on the upstream face of the dam at this highest section is 220 tons. The spillway length is 1160 ft. Beyond the abutment on the Canterbury side, a weir dam of 118 ft in length has been constructed, this being carried into the ( solid rock for a depth of 60ft feet. Fight Against Nature From the very conception of the undertaking, Nature has set dead against the engineers. The elemental forces of Nature have shown him little mercy. Long years have been occupied in the struggle, but the eni gineers have never trusted the roaring giant in its varying moods. The men | under the direction of the engineers ! have had to blast out, fill and bridge : every inch of the way. Hour after hour, night and day, there has been a continuous warfare in the battle with the hitherto untamable Waitaki. With science and inventive genius as his allies, man has set his puny strength against the elemental powers of Nature —flood waters, shifting shingle, adamant rock and the possibilities of the I appearance of man’s most dreaded I enemy, disease. Nevertheless,'in spite of all resistance; the engineer and the rank and file of his headline army of conquest, have built them citadels of concrete in the midst of foamy waters. Man’s dreams have materialised, and the great dam now spans the mighty Waitaki and the turbulent waters now move under majestic control in the channels where they are harnessed to the wheels of industry. The Giant’s Toll In this hour of triumph, it should not be forgotten that the river has taken toll of the lives of some who belonged to the great host of workers who were engaged in the task of curbing its freedom. The brain and blood, thew and muscle, nerve and soul which have been concentrated and sometimes sacrificed in this conquest, should not be forgotten. The men working on the gigantic undertaking toiled long and hard, tolerating rigorous climatic conditions, and suffering isolation ungrudgingly in the

battle to harness one of j the most difficult rivers in j the Dominion. They are [ the unconquered warriors i in one of the most glorious | victories New Zealand has j written in the pages of peaceful progress.

The Capacity of Waitaki The interior of the power house is surprisingly beau- ■ tiful, its walls rising. ! cathedral like, to a height I of 130 feet. Three windows | from the floor to the ceil- | ing occupy almost all the wall space of the northern

and southern ends. A maze of delicately tuned machinery is installed here. At present only two turbines are working, but as soon as the increased demand for electric power warrants it, others will be installed. These are of the vertical type and develop a maximum of 23.000 horse power, at a peripheral speed of 61 miles per hour. There is provision for five units, but at present only two are installed.

From the screened intakes. three penstocks, each twenty feet by twenty feet, supply a million gallons of water per minute to each turbine, with a head of 70 feet. In front of the power house and connected direct to the generators, are two transformer banks of three single-phase units provided in order to step up the current from 11,000 volts to 110,000 volts.

The switching station consists of two bays, each of steel latticed towers and cross girders 50 feet high. The leads from the power house are carried overhead to the station, w r here the disconnecting switches are located. On the same platform, which carries the transformers, are the in:ransformers. From here,

188 great latticed steel towers carry power across waters and shingle beds, to the Glenavy sub-station, a distance of 38 miles. The strain towers are from 50 feet in height, the suspension ones, about 60 feet high, while the average span between each tower is 16 chains.

When Waitaki Roars

And now that man has brought the giant under some measure of control, the biggest problem of all that has to be faced by the engineers who accepted the task of taming this giant of Nature, which draws it strength from the eternal snows in the lofty Alps is the dispersal of the energy of the enormous cataract of water that passes over the spillway, when the river rises above normal. When the Waitaki is in flood, the mighty waters of the river will surge over the dam in an almost terrifying torrent twelve feet high. Like a miniature Niagara, the Waitaki will at times, hurl itself at the dam in a torrent flowing at the rate of 70 feet per second. How could engineering hope to dissipate this energy and defeat the frantic effort of the giant in its fury to destroy man’s attempt to curb its mighty swoop towards the sea. V-shaped ventilators set at short intervals across the full width of the

dam act as disruptors. The object of disruptors is to reduce the momentum of the rushing falling waters and the effect of air coming through these small vents is most extraordinary. To dissipate most of the energy the engineers found it necessary to take the foundation of the dam to such a deep level that a cushion of water would be created. Water falling on water cannot do a great deal of harm, but it will have the spectacular effect of churning the torrent into a foaming roaring chaos, with whirling columns of vapour-like spray, a spectacle that will be one of the sights of the great undertaking. From below the dam, the liberated

waters start anew on their adventure to the sea. The base of the dam extends to the form of a curve and at the finish it has an upward slope. The tendency of the rushing water of the river, as it hurls itself over the spillway, will be to follow the curve to fight against itself and prevent the flooded river destroying man’s effort by undermining the foundation of the great dam. Looking Into The Future. To-day the great undertaking will be officially put into operation by the Governor-General. To South Canterbury, the harnessing of the Waitaki means that no risk of shortage of hydro-electric supplies will haunt the rural and town interests. A mighty motive power has been made available to meet the lighting, heating end power needs of the province. To many the harnessing of Waitaki is full of symbolism. The sue- *

cess of the engineers associated with the Hydro-Electric Division of the Public Works Department in conceiving so bold and comprehensive a hydro-electric undertaking for the generation of tens of thousands of horse power of energy and then translating the vision into reality may be regarded as an inspiration to the public of South Canterbury, to go forward into the future with strong faith in themselves and implicit confidence in the wonder- j ful potentialities of this / fertile and beautiful / district. J