LAST LENGTH PLACED

Evening Post, Volume XCII, Issue 108, 3 November 1926, Page 7

LAST LENGTH PLACED

THE BIG MAIN COMPLETED

ORONGORONGO TO KARORI

WHAT THE NEW SUPPLY MEANS.

In tho presence of the Mayor and a number of the councillors, Mr. J. M. Morice (Engineer in Charge of Waterworks and Drainago) and other officers of the Engineer's and Town Clerk's Departments, the last length of the Oron-gorongo-Karori main was placed in position at half-past two yesterday afternoon, the Mayor being in charge of the sheerlogs and block and tackle department, which lowered tho ton or so of steel main into place. It was impossible to estimate in & s d tho value of a good water service to a city, said Mr. Norwood; a , city could not bo a city without that supply. Wellington had had to go far for its water, but had now a supply equal to anything anywhere. In many other parts of the world great expenditure was necessary to render water suitable? f6r human consumption, but New Zealand towns generally, and Wellington in particular, were fortunate in that they obtained direct from the stream water of excellent quality. SOME FIGURES. The new main from the Orongorongo stream to the Karori storage dam, said Mr. Norwood, was 104,G93ft, or just under twenty miles, , long, and was made up of 21-inch (interval diameter) lock-bar steel pipes, with walls of up to 7-16 in thick. Each length'was tested at the maker's works to a pressure of 7001b to tho square inch, and in position (to test tho joints) of 4701b, the estimated maximum working pressure being 4001b to the square inch. - The intake at Orongorongo was 800 ft above sea level, said the Mayor, and the discharge at the old Karori reservoir 463 ft high. The calculated carrying capacity of the main when new was four and a half million gallons per day. Twelve-inch branch mains led to 400,000-gallon reservoirs to servo Ngaio and Khandallah, and at Messiues road to serve the Karori township. The water would be delivered by gravitation' in each instance, and thus pumping charges would be saved. About two and a half miles of the main laid through the Orongorongo tunnel was carrying water in March, 1924, and tho first lot of the remaining seventeen miles of main was delivered by the Spiral and Lock-bar Steel Pipe Company in May, 1925, and tho last lot in March, 1926. The expenditure to date was about £180,000, and there was still to pay approximately £14,000, a total of £194,000. Mr. Barrance, the resident engineer at Orongorongo, was in charge of the laying of the nino miles of main from Orongorongo, and Mr. Tinney, waterworks ovorseer, had' charge of tho work from that point to Karori reservoir, a distance of nearly eleven miles. Mr. Swinburne (assistant-waterworks and drainage engineer) directed the survey and preparation of plans, and carried through that work with the fullest success. Each of those officers and those under them carried through their work in very able manner. THE TWO-MILE TUNNEL. ' _,n essential part of the scheme of supply, continued Mr. Norwood, was the driving of the Orongorongo tunnel through two miles of solid rock by Mr. (now Councillor) R. Semplo and his party. The road to the tunnel was started in March, 1920, by day labour, and the first co-operative contract for a tramway to tho top was lot to Messrs. Matthew and party in May, 1920. Other contracts were let for the erection of huts, approach roads, pack track, etc., in 1920 and 1921. Power houses were erected at Wainui and Orongorongo in 1921 and 1922, and drilling at the Wainui end was started by hand in December, 1920, and by machine on 6th October, 1921, and at tho Orongorongo end by hand in March, 1922, a dby machine on Ist October, 1922. The two drives met on 23rd February, 1924, 6057 feet from the Wainui end and 4466 feet from Orongorongo. The concrete lining of the tunnel was begun in November, 1924, and was completed in April last. The total cost of the tunnel and all connected works, bridges, weirs, power houses, camps, roads, pack track, etc., was £,160,000. So admirably was the work of tunnelling carried out that the error in alignment when the two drives met was scarcely noticeable. So also, excellent work was done in the construction of the weirs, bridges, power houses, and' other works. These works were a part only of a scheme recommended by the late Mr. W. H. Morton, for his scheme included also a great storage; reservoir at Wainui. In the meantime that was not gone on with, but the new main would give an ample supply to Wellington for some years to come. BENEFITS THAT WILL ACCRUE. Owing to the configuration of Wellington, an enormous amount of pumping has to be dono to lift the water to the higher levels, but the new main, with its higher pressure would make it possiblo to supply daily half a million gallons of water to the higher levels at present pumped, the Mayor continued. This would bo a direct economy, and there would al3o be a general improvement in pressure on levels at present not always satisfactorily served. The pipes for the main were constructed in New Zealand, in Wellington itself, and he wished to pay a tribute to the contractors for the excellent way in which the work had been carried out. Questions had been asked, continued Mr. Norwood, in regard to tho council's intentions as to applying the penal clauses of the contract on account of le.to delivery by the contractors. That had yet to be decided, but tho council would, ho felt sure, deal with the. matter reasonably and impartially, having regard to all aspects Of the work. Wellington, concluded Mr. Norwood, was to be congratulated upon having a water supply which guaranteed the health of her citizens for many years to com?. Councillor H. D. Bennett, chairman of the Works Committee, also congratulated those responsible for tho work, and spoke of the benefits of improved steadiness of pressure and more ample supply. SIX YEARS* WORK. Mr. Morice thanked the Mayor for his remarks upon the work of the staff.; The Orongorongo-Karori main, he said, would carry a higher pressure than any other water supply main in New Zealand, though the Mangahao power mains were under a rather higher pressure. The council's staff had had a great deal of experience in laying enstiron mains, but steel mains, they found, offered many difficulties. Still, steel it had to be, on account of the great pressure. He hoped that it would be possible to test the whole main next week, and remarked in that regard that although test pressures could be applied to the pipes themselves before they were laid, it was not possiblo to test the joints till they were in position. "I have thought this main, worked at this main, and dreamed of this main

for the past six years," concluded Mr. Morice, '' and to-day tho. last length has been laid." Mr. Morice, said tho Mayor, was now drawing near his retirement from the service of tho Corporation, and it was very fitting that he should complete his career of service to the community with a work that was unique as far as New, Zealand was concerned.