WATER SUPPLY.

Auckland Star, Volume LVII, Issue 18, 22 January 1926, Page 9

WATER SUPPLY.

TAUPO AND WAITAKERE. REPLY TO CITY ENGINEER. TAUPO ENGINEER'S CRITICISM. At a mooting yesterday of the commiitee of the Provisional Auckland Provincial Water Board, Messrs. J. Rogers and W. A. Gray, the board's engineers, submitted a report in reply to recent criticism by the City Engineer. ••Iα view of the criticism which Mr. Bush has made of the estimates embodied in our report of March 2:3, 1925," say the engineers, "viz.: £2,482,000, of which amount £225,000 was provided to cover contingencies, and also the estimate of £325,000 for the purpose of installing a pumping and filtration plant for \he temporary supply of water where required immediately, we beg to make the following report: The whole of the pipes, fittings, etc., of the temporary Mipply constitute an integral part of the main Taupo scheme. During the period we were engaged upon the Taupo water supply scheme w e were in close touch with manufacturers, merchants and contractors respecting cost of the requisite material and labour, and upon our combined experience, coupled with the information \v e had gathered, the estimated expenditure embodied in our report was compiled, and we are confident will be found correct. "We have quotations from manufacturers' agents for the necessary plant to equip the North Shore emergency scheme, which can be ratilled at any time, and we have already suggested that ■ some eminent English engineer be invited to report upon the scheme, and on the estimates therein, and we now beg to repeat the suggestion."

The engineers refer to the discrepancy betwen Mr. Bush's criticism and thnir estimates. "At the early part of 1021 the City Council allowed two weeks' time for receipt of alternative tenders for steel and cast iron pipes, for which one tender for each class of pipe was received. Tho tender submitted by the RVanganui Pipe Co., Ltd., for 33-inch diameter steel pipes was accepted at £96,483, including valves (£7200), leaving £80,283 for the steel main. Mr. Bu~h makes a comparison between our estimates and the tender received by tho City Council. Our estimate is based on cement lined steel pipes. On the basis of quotations obtained it would be possible to provide 33-inch cement lined sted pipes at 29/ per foot. The price for the pipes to Titirangi works out at 39/6 per foot, and these are not cementlined, but bitumen-lined, with shorter life and smaller carrying , capacity, Mr. Bush assumes as a matter of course that everyone must pay the same price as he did, but in this hn is quite mistaken." At least four months would lie allowed for receipt of tenders for the Taupo water scheme, material and labour, and the engineers are assured that the kee? competition anticipated would ensure their estimates being upheld. Policy in the Waitakeres. In an address to the ratepayers by the Mayor of Auckland on November 20, 1023, continue the engineers, lie stated that £300,000 was needed to develop the resources of the Huia Valley, and this amount was allocated. It appears that the expenditure has exceeded allocations to such an extent that it is now proposed by the City Engineer to vary the scheme and raise the Waitakere dam, and erect a subsidiary dam across this saddle on the western side of the Teservoir. These works are estimated to cost approximately £SO,OOO. The Waterworks Committee had recommended that the "work of raising the dam be carried out from the balance of the loan money already authorised, and this recommendation was adopted by the Council, i'rom this statement it would appear that the Huia Valley gravitation scheme Las been abandoned in favour of raising the "Waitakere reservoir dam, which scarcely corresponded to the details given when the loan was proposed. It >vould be interesting to learn the facts which had made such a drastic change in policy necessary, unless it was for the special object of supplying water to the North Shore boroughs, which would provide their own independent pipe line; otherwise. no doubt, the ratepayers would be approached at a subsequent, date to authorise a loan for duplicating the pipe line from Waitakere to Khyber Pass or PonBonbv reservoirs.

The City and North Shore.

It might be interesting to note that in an address given by the Mayor of Auckland on "September 22, 1921, he stated: "In consideration of this matter it has not been felt incumbent upon the Council to consider the position of the North Auckland district; this latter obligation should be watched and dealt with by those immediately responsible." Furthermore, the City Engineer in a comprehensive report to the City Council, dated September 21, 1921, stated that he had purposely not included the North Shore boroughs, and that if the Northern boroughs could work out their own salvation in the matter of water gupply. it was much better so. Notwithstanding the expre:/sed views of the then Mayor and the City Engineer, continues the report, the City Council has changed its policy by adopting the Waitakere storage for soma ulterior object, and on this change the city ratepayers have not been consulted. Furthermore, the scheme of augmenting the capacity of the Waitakere reservoir ■was never seriously considered by the City Engineer until quite recently.

Cost of Waitakere Work. The engineers direct attention to the drainage area of (the ten watersheds comprised within the southern portion of the Waitakere Ranges, given by Mr. Bush. The area extended from the lower Nihotupu to Kare Kare, Tiha and Marowhara. Mr. Bush wisely refrained from expressing any opinion on the cost of constructing impounding reservoirs, tunnellin" conduits, etc., but, judging from the nature of the country, and the cost of works recently constructed, and now in progress, the total expenditure •would exceed the estimated cost of the Taupo scheme. Ten or twelve reservoirs ■would he required to intercept and impound the water over the area alluded to above, while on the other hand, Lake Taupo was. in itself, a natural reservoir. Taupo water was free from contamination, and absolutely pure, but water from the Waitakere Ranges was, as everyone knew, of very dubious quality and required some considerable expenditure on filtration to make it fit for domestic use.

Available Waitakere Supply. '•The daily yield and available supply of water from the Waitakere Ranges i=. a very serious matter," say (the engineers, "which fact is no doubt recognised by the city council, as pumping operations have 'been in progress from the Western Springs for some weeKS, from which Mr. Bush estimates the yield at 1,400,000 gallons daily. We do not

agree with (the city engineers present conclusions respecting rainfall and daily yield."

The Teport gives some figure? of rainfall and yield, and proceeds:—"We are of opinion "that the city engineer's calculations of the available rainfall, based on a yearly average, are fundamentally erroneous, "and the conclusion arrived at of lOSOgal per day per acre would not nearly be approached throughout (the year of drought; and the drought of IS'l4, or a worse one, may occur again any time, with a larger population to supply.' .

In conclusion, the report says: "He (Mr. Bush) has recommended different 1 things at different itimes. He has paid more than was necessary for pipes: the time for laying same has been greatly exceeded. He is now engaged in decrying the Taupo water scheme, although the scheme he offers as an alternative, depends on artificial storage: ijts cost will be about that for the Taupo scheme. A dry summer would plunge the whole area into dire trouble. Its life was not quoted two years ago as more [than 15 to 20 years, and it is quite incapable of providing for the areas outside the city. which are already large and are rapidly growing. Vet lie' jnvtites people to accept his scheme in preference to (the Taupo scheme, and strains figures in order to damage the latter."