ARAPUNI

Rotorua Morning Post, Volume 2, Issue 363, 26 October 1932, Page 6

ARAPUNI

what experts say THE FULLEST AND MOST COMPLETE TESTS MADE. FIVE YEARS' INYESTIGATIONThe safety of Arapuni was recently disc-ussed before the Wellington I'lnlosophical Society by Dr. J. Henderson, Mr. F. W. Furlcett and Mr. F. T. M. Kissel. Dr. Henderson introduced the subject by outlining the geological feattures of the North Island and of the Arapuni area in particular, dealing first with the period when the North Island was th'e plaything of stupendous volcanic forces. Having described the geological features of the various alternative sites, he said that one advantage of the Arapuni site was that it lay thirty miles from the western edge of the unstable volcanic belt, whereas Aratiatia and Kaituna were within that area. The site of the dam at Arapuni had, before any decision to build it had been arrived at, been very thoroughly investigated. Rock at the dam site had been rigidly examined and thoroughly tested for porosity, for permeability, for strength to resist erosion by water under pressure, and for other properties. The strata at the dam site had been proved to be strong enough and resistant enough to bear the weight of a dam of such a size as hau been built, and to sustain the thrust of the water when it was filled. At Aratiatia, on the other hand, the rock was weak and poorly compacted, and in a general way no stronger ■ than the weakest rock at Arapuni. Many Tests Made. Mr. Kissel said that his survey would not go back millions of years lilce Dr. Henderson 's, but for only sixteen. Ha then detailed the various surveys that had been made of the possible alternative schemes (Kaituna, Huka Falls, and Aratiatia). After the consideration of details over a period from 1916 to 1923, the choice was narrowed down to three possible schemes, the case for Arapuni seeming the best of all the alternatives. Mr. Kissel then gave full details of all the exploratory shafts that had bem sunk at Arapuni, and of the elaborate tests made on the rocks. All the rock shown by tests to be weak had been cut out when the dam site was excavated. There was no evidence, he said, of the presence of earthquake faults or cracks. Conditions at the power house site had been found to be similar to those at the site of the dam. Oi e great advantage which the Arapuni sch >me had over any of the alternatives was that it saved a consideraole sum in transmission costs, and iigures were quoted to show how very much cheaper electric power generul d by the North Tsland schemes was than that generated by steam plants. No Rushing In. An emphatic denial was given by Mr. Furkert that they had blindly rushed into the Arapuni scheme. It had been said that if the Government had listened to its engineers it would not have gone on with the scheme, and it had also been said that there was no proper inVestiga&oft, "But you have heard enough this evening to prove that it was given a little thought," he said, more attenion being paid to the foundations than to any other part. There were no preconceived ideas on he subject, and nothing was done in a hurry. "Of course we all knew there was a risk: there always is when you head up water. But the point was, whether there was undue risk." Full investigation had shown that Arapuni had advantages over alternative schemes, and, even when the stability of the country had been proved, there was no hurry. "Our object to-night is not to prove that we were right or wrong in building Arapuni," Mr. Furkert went on to say, "but to show that we did not go into the scheme without the fullest and most complete investigations, and that we have done. For five years the scheme was under expert consideration, with tests and bores being made all the time. To say that we rushed bull-headed into thi sthing is ridiculous and when people say it it makes me loss my temper. "The investigating committee who finally recommended the adoption of the scheme consisted of the late Mr. W. H. M orton, the Wellington city er.gineer, who was notorious for his caution; Mr. J. Marchbanks, the Wellington Harbour Board engineer, who has a reputation unsurpassed in this country, and who did not care two hoots for the Government's views on Arapuni; Dr. Henderson, and myself, neither of whom is altogether a fool."