New Scheme to Give Summer Water Supply

Sun (Auckland), Volume II, Issue 607, 8 March 1929, Page 1

New Scheme to Give Summer Water Supply

LOWER NIHOTUPU PROJECT POSTPONED BY COUNCIL Th« lower Nihotupu pumping scheme. which has been before the City Council for some time, is suggested as the next water development in Auckland. The project, which will cost the city £362.000, is to be considered at a special meeting a fortnight hence. The Auckland City Council, at its jneeting last evening-, had before it the recommendations of Mr. H. 11. ; Dare, civil engineer of Sydney, who | agreed largely with the findings of the Auckland Water Commission and also I with the views of the city engineer. I Mr. W. E. Bush, upon the desirability c£ this scheme. COSTS EXAMINED In a separate report, Mr. Bush out- ! lined the salient features of the Lower I Nihotupu pumping scheme, the main I purpose of which would be to provide for the summer demand. The load factor, he said, would not be an ideal one, but by careful arrangement of the draw-off from the gravitation dams and the utilisation of steady pumping of the quantity required from the lower Nihotupu supply, the actual coat of power could be kept at a reasonable figure, and would increase from £lO a day for one million gallons to £3O for six millions. The proposal. Mr. Bush explained, was to utilise the waters of the Nihotupu Stream below the main gravitation dam and reservoir, by the construction of a reinforced concrete dam of the slab and buttress type on a site Immediately above the bridge on the Brooklyn-Huia Road, having a spillway height above stream level of 70ft, and impounding 1,350 million gallons of water at that level, of which 3.300 million gallons would be available for draw-off at the lowest intake. This, with the catchment area of 3.100 below and any surplus water flowing over the weir of the gravitation dam, should provide a supply of 6.000.000 gallons daily, the whole of which would require to be pumped and delivered by a 27-inch rising main to the western end of the conduit section of the aqueduct at Mackie’s Rest. The estimated cost of carrying out the work on the data now available as to depth of bed rock on the site, which had been ascertained by trial ! holes, would total £362,000, made up as follows Dam and reservoir £250,000 j Pumping machinery (electrically driven), and buildings 18,000 i Rising mains and specials .. .. 12,000 Additional filters at Titirangi . 20,000 I Engineering and contingencies 45,000 i Cost of raising loan 17,000

STAND-BY PLANT Mr. Bush also dealt with the desirability of a stand-by plant. "I have discussed the question of power supply with Mr. F. J. H. Wilson. engineer to the Waitemata Elec-tric-Power Board,” he said, ‘‘and I anticipate no difficulty in obtaining an adequate supply at reasonable rates, and therefore I would recommend the installation of electrically-driven series centrifugal pumps, similar to those already installed at the Symonds Street (Khyber) pumping station, and in order to provide both for the pumping of minimum and maximum quantities of water, it would be advisable to instal the pumping machinery in the following units:

1 of 3 million gallons capacity daily. - of 2 million gallons capacity daily. of l million gallons capacity daily. 1 of i million gallons capacity daily. While the whole capacity of the plant would not necessarily be required immediately, its installation ■*'ould prove a valuable stand-by in case of a break in the Upper Nihotfipu or Waitakere pipe lines.” The council will discuss this report ;, t a special meeting on Thursday, March 21.