Harnessing The Waitaki

Sun (Auckland), Volume II, Issue 484, 13 October 1928, Page 28

Harnessing The Waitaki

Work Begins On Big Hydro-Elect iHc Scheme. Dam 100 Feet High: Lake Five Miles Long.

(Written for THE SUN by (H. E. WEDDE.) «-pvHE SERENE quietude of the back A country stations along the banks of the upper Waitaki River beyond Kurow, emphasised by the bleat of sheep and the scurry of rabbits, has been rudely disturbed by a small army of workers engaged in the stupendous task of harnessing the latent Power of a mighty river for the benefit of mankind and industry. Hera in the solitude of the tussock and matagouri, a mushroom township, Awakino, has spiking up overnight, and the air is full of bustle and activity as man pits his brain and muscle to control the mighty forces of Nature and turn them to his own account. The tooting and rumble of motor-lor-ries and cars, the ring of pick and shovel on rock and gravel, and the clang of hammer on steel and anvil reverberate in echo from the; fastnesses of the snow-clad mountains be-

yond , creating a man-made din above the music of the swiftly-flowing waters. Transport Facilities. The visitor to the locality first meets with unwonted activity at Kurow, where a temporary full-gauge branch line is being connected with the existing railway at the point where it turns towards the Hakataramea Bridge over the Waitaki. Most of the construction is over level, open country, and sleepers and rails are now ready for two miles, or half the distance from Kurow to the dam site. Where sharp faces abutting on to the river are encountered a narrow bench is cut out of the rock, allowing only sufficient clearance for trains, thus keeping the cost of construction down *o a minimum consistent with safety. In these days of the proved utility of motor transport, the advisability of laying down a temporary railway will probably be questioned by some, but when the huge amount of material required for the dam is taken into consideration, all doubts of the superiorly of the railway over the motor for hat class of work are removed. The total quantity of concrete required for the dam will be 170,000, •’ubic yards, for which nearly 40.000 tons of cement will be required, while 1000 tons of steel sheeting will be required for coffer-dams. Public Works locomotives will be used with the usual railway rolling stock, so that by the rails to the works the cost of transhipment is obviated. Awakino Township. Facing downstream at the dam site two large terraces extend on the right from the river to the foothills. On the *ower of these is the newly-created :ownship of Awakino, comprised of tents and huts, the latter being mov-

able because during construction the flat will become submerged. Here is accommodation for about 160 men—mostly married with wives and families —who are chiefly engaged in railway construction, erection of camp accommodation and housing. water supply, and electric transmission line. Comfortable quarters are provided, and in a community dining-room are served appetising meals for 120 men, with further provision to be made when the full complement of workers is engaged. On the upper terrace a large Y.M.C.A. building is nearing completion, which is to accommodate a billiard room, camp library, post office, and a picture theatre. On the fhrther side of the river the only sign of habitation is a tent, pitched at the foot of high hills by a worker, who apparently prefers his own company to that of the crowd. The camp has not been allowed to grow up at random, with huts and tents higgledy piggledy over the landscape, but has been laid out on a carefully conceived plan in order to facilitate the construction work when in full swing. Railway sidings and loops for the economical handling and haulage of gravel and material are allowed for, and hutment allotments are pegged out in available vacant spaces. An area has been reserved on the upper terrace for the permanent power-house staff, and foresieht has

been shown in the planting of a shelter belt of trees around the reserve, these growing into utility while the work on the dam is proceeding. Electric power, for which the transmission line is nearing completion, will be supplied from Coleridge through the Waitaki Electric Power Board, 300 h.p. being available. The use of electricity opens up the question of labour required, and though, as the work progresses, there will be room for many more men to be engaged, the unskilled labourer will find little scope for his services, as the electrically-driven machinery, compressed air drills, etc., need to be attended by skilled workers and electrical experts. The Dam Site. The source of the Waitaki lies in the snow-clad mountains of the Alps, where the snows of glaciers find their way as they melt into the lakes of Tekapo, Pukaki and, Ohau. From these lakes there flow streams which join at a common point, later meeting the branch of the river which flows past Omarama, some miles above the chosen site. Here, Greywache rock, stretching across the valley from hillside to hillside, provides a very reliable and excellent foundation for the dam. In the river itself, a boringplant pontoon is taking soundings of the solid rock for the foundations, while on either bank the soil is being removed, laying bare the rock surface. In passing, it may be mentioned that on the right bank the operations are making available a supply of gravel to be utilised for ballasting the railway, the excavations thus serving a dual purpose. . Over all the dam will be rather more than a third of a mile in length, the abutments at either end being 12 feet

Provision Made For Generating A Hundred Thousand Horse-Poioer: N.Z. s Biggest Scheme

l higher than the spillway section, ; which extends tor 1200 feet. The I height of the spillway section will be 105 feet from rock bot- ; tom, or on an average 70 feet above the present water level and 35 feet be- ! low. The depth of gravel varies from ils to 30 feet. The base of the dam will be 100 feet wide, and the down. | stream face of the spillway will be j curved to discharge the flood waters. I Compared with the Arapuni dam, which is high and narrow, and curved against the tremendous weight of ; water In the lake above, the Waitaki dam is not so high, but much longer. The dam, however, has been curved and lengthened purposely to get the length of spillway to discharge flood water, and also to lead the water to the power-house on the right-hand side. At Arapuni the Waikato River was diverted off its course, thus laying bare the river-bed, but such a method cannot be utilised in the construction of the Waitaki dam. In this case the

first stage will be the construction of a huge coffer-dam for about a third at the width of the river. Long steel sheets, with tongue and groove fastenings, will be driven on the four sides to rock bottom, and when this is pumped dry, the foundations are exposed for construction work, in this section will be provided a number at sluiceways, sufficient to discharge the normal flow of the river. When completed the current will be diverted towards these.sluicewavs, and the other river sections and shore length will be proceeded with. On completion of the whole length of the dam, the sluiceways in the first portion will be closed, and with the lake filled to the level of the spillway crest the water will flow over the spillway. The lake thus formed will be about SO feet in depth, extending up the valley for a distance of five miles. Incidentally, one station homestead and the valley road will be completely submerged, necessitating the deviation of the road on to the upper terrace, and the erection of a bridge at the upper end of the lake to afford access to stations on the left side of the river. The Power-House. The hydro-electric plant capacity In New Zealand Is 176,000 horse-power, Arapuni being the largest with 60,00# h.p. The Waitaki power-house, to be built at the right-hand end of the dam, will be between 400 and 500 feet long, with a height of about 140 feet from its bottom draft tubes to the top of the building. Two turbines of 20.000 h.p. capacity will be installed at the commencement, developing 40.000 h.p., but provision is made for three additional turbines of similar capacity to be added as required, bringing the total h.p., when at full canacltv, to 100,000.