Problems of Arapuni

Sun (Auckland), Volume I, Issue 257, 20 January 1928, Page 8

Problems of Arapuni

DEPARTMENT’S TASK

Difficulties Not Yet Over

SIX weeks ago tke New Zealand Public Works Department announced its ability to accomplish what ArmstrongWhitworth, Ltd., would not attempt—the construction of the Arapuni powerhouse according to the original plans ol the scheme. _ Further, it undertook to complete the task in eighteen months, of which period one-twelfth has already eiapsed, without revealing any appreciable advance since the department took over.

TT'NGINEERS in all part* of the Effl--l-i pire will watch with Interest this effort of the New Zealand Government and their interest will be paralleled by the attention the taxpayers of the Dominion will direct upon further Happenings at Arapuni. Any confidence the taxpayers feel will hardly be strengthened by recent developments, which deprived whole communities of power and water for days at a time, nor by the situation at Mangahao, a public works project, where the original dams failed so signally to retain an adequate summer

supply that a third costly structure had to he built, while in the meantime private steam plants from Wellington to Wanganui were called on to eke out the power supply in what still threatens to be a desperate industrial emergency. At Arapuni the predictions that the river, after the first mad week of its plunge over the spillway, would settle down to a life of sober respectability, have not been fully realised. Erosion is still occurring, and on a scale so extensive that at Mercer,

many leagues away on the lover river, a plank immersed under the cloudy water is quickly whitened by a chalky deposit from the burdened currents. Only a bold man would now assert that the pranks the river may play below the spillway will be subject to a time-limit, and there >.s still a chance that doleful pjognostications may be fulfilled. When the river glides majestically over the crest of the spillway it begins a descent without parallel elsewhere along its course, and the wayward currents, eating back, may yet menace the vicinity of the spillway, or cut a fresh channel to a junction embarrassingly close to the powerhouse site. Arapuni as it stands, with the dam completed and the powerhouse in existence on paper only, is a huge missfire. The dam is an impressive structure, a tribute to engineering skill and daring, but much that has happened elsewhere simply points the earlier utterances of critics of the scheme, and allows them to say, "1 told you so,” without fear of defeat in debate. WATER AT POWERHOUSE A complicating factor is the extent to which deposits at the junction of the old and new channels have caused water to back up toward the powerhouse site. Consequently, the riverbed, instead of being perfectly dry, is still flooded, and this is an almost rainless summer, so that those on tbe spot, far from being reassured by statements that the water is falling, are asking what will happen, both in the riverbed and below the spillway, when floods come along. The deposits at the confluence can always be cleared by the opening cf the diversion-tunnel gates, but this action would again have an adverse effect at Horahora. Some form of sluicing, nevertheless, may be periodically required, or else lie department may have to undertake expensive coffer-damming before it can start on the perwerhonse. foundations. Meanwhile, the contractors are applying the finishing touches to No. 1 contract, consisting of the dam and headrace, before presenting the linal certificates and handing their work over to the Government. Before the settling-up is completed, an immense amount in extra claims will have to be considered. Everyone who has built a home knows how the extras, what with a switch here and a panel there, mount up jn even a small job, so it is apparent that there will be some substantial claims to be adjusted on a contract of such magnitude as Arapuni.