WATER SUPPLY

Otago Daily Times, Issue 23055, 4 December 1936, Page 9

WATER SUPPLY

THE CITY'S • REQUIREMENTS DEEP CREEK SCHEME COMPLETED LIBERAL FLOW MADE AVAILABLE NEW PIPE LINE IN USE Assurances that Dunedin now possessed a supply of water that would fully meet its requirements were given yesterday at a ">remony at which the Deep Creek scheme was brought into operation by the turning on of a supply carried through 36 miles of pipes The proceedings took place at the new control room at the Ross Creek reservoir. The Mayor (the Rev. E. T. Cox) presided, and those present included the chairman of the Water Committee 'Cr Begg), the Postmaster-general (Mr F. Jones), members of the City Council, local members of Parliament, the city engineer (Mr J. G. Alexander), the town clerk (Mr G. A. Lewin), representatives of local bodies, and a number of prominent citizens. It was stated that the scheme, which was approved by the ratepayers in 1933, would make available an immediate supply of 2,500,000 gallons of water daily, and was constructed in such a way that it could be readily extended if the need arose in future years. Not only had fears of a shortage of water in drought periods been dispelled, but the augmented supply also afforded means of protecting the health of the people. FEARS REMOVED The Mayor said that when he asked Cr Begg, under whose administration the scheme was conceived, designed and executed, to turn on the tap releasing into the city reservoir and thus into the city reticulation system the water from Deep Creek, Dunedin citizens would for many years to come be able to sleep in their beds, fearing neither famine nor pestilence, two of the great scourges which from time immemorial had afflicted the human race. Cr Begg and the Water Committee, with the staff, deserved the heartfelt thanks of the community for carrying out the project. It seemed a strange thing that in almost every large centre in the Dominion there should be uncertainty about water. He had lived in five cities, and in four of them the people always feared the sunshine and welcomed the. cloud. Incidentally, he might point out to those who are in the habit of decrying Dunedin's low temperatures that had it not been for that very fact the city might have had in the past some very serious outbreak of fever. These fears were now at an end. The inflow of 2,500,000 gallons daily through the scheme, said the Mayor, meant an increase of 60 per cent, in the water supply in drought periods, besides which the amount of the intake above the normal needs of the city in ordinary times would permit of the reservoirs always being full. This scheme not only provided against a water shortage to-day, but was the first step towards a future supply as the growth of the city demanded further increases. It was possible not only to duplicate the line to bring water from the same intake, but the large area from which the supply came would enable provision on a much larger scale to be made to meet the growth of the city in days to come. GOVERNMENT'S CONGRATULATIONS Mr Jones extended the congratulations of the Government upon the completion of the work. Dunedin had waited a long time for its increased water supply, he said, but the scheme had been completed in the specified time, and would be ready for the summer demand. Credit was due to the Mayor, also to Cr Begg for the persistent way in which he had furthered the scheme; and Mr Alexander and his staff were to be congratulated on the manner in which the work had been accomplished. The scheme had been of great benefit during the depression in respect of the amount of employment which it had provided, and he was pleased to be able to say that not a penny of the unemployment

funds had been used upon it. Thus a greater amount had remained available for others in need of work. It was essential, the Minister added, that a city should have a plentiful supply of water, and it was surprising that so many years should have passed before the value of utilising the available sources of water was realised. The city had done a great deal for the unemployed by the introduction of "standard" works. In fact, he did not think that any city had done more for the workers than Dunedin. He hoped that the City Council would inaugurate other works for the benefit of the city. If it did so, the Government would be only too pleased to cooperate. GROWTH OF SUPI-LY Cr Begg said that the function marked an epoch in the development of the citv's water supply. A similar gathering had taken place on December 15,1881—55 years ago—the occasion being the turning on of the Silverstream supply—in itself a scheme ot considerable magnitude at that time The race capacity, with careful maintenance, had never been greater than a little over 3,000,000 gallons per day. Since then, the whole water system had from time to time been greatly augmented by the purchase of land in various areas, with a view to conserving and purifying the supply, by the bringing in of the Waitati-Leith supply, the linking up of Powder Creek, the construction for storage of Sullivan dam (the latter system having been originally designed for supply to all high-level districts), and the enlargement of the southern reservoir. The whole of the supply in the past, Cr Begg continued, had been taken from the same restricted area—Flagstaff, Swampy Hill, and Silver Peaks, all were subject, more or less, to the same meteorological conditions and influence, the catchment totalling 13,200 acres. With the natural growth and development of the city the existing supply, which originally had been sufficient for the requirements o± its time, had become insufficient for the needs of the district. Hence it became necessary to investigate further supply from outside districts, and, in 1920, a scheme to bring in Lee Stream had been submitted to the ratepayers, but had been rejected by a large majority. After this proposal had been declined the enlargement of the southern reservoir had been undertaken. It had been increased from 25,000,000 gallons to approximately 65,000,000 gallons, sanction having been obtained from the Public Works Department, whose officers had intimated that any further storage in the vicinity of population would not be looked upon with favour. FULL INVESTIGATION In 1924, Mr J. G. Alexander, shortly after his appointment as city engineer, had been given the task of reporting on the whole water system. Meanwhile, pending receipt of this report, many and varied proposals had been propounded by the public in general, a number of them being of an extremely novel nature. During this period the city engineer had had records taken of the rainfall and flows of various streams in the respective areas, and, finally, in 1929, Mr Alexander had submitted a very exhaustive and comprehensive report, covering all likely catchments, from the upper reaches of the Waikouaiti River in the north to the Waipori River in the south, and had recommended that the bringing in of 5,000,000 gallons per day from Deep Stream at an approximate cost of £380,000 be investigated in detail. The lowest stream flow record of this stream, from an area of 40,600 acres, taken over a dry period, had been 13,000,000 gallons per day. The council had carefully considered this proposal from a financial aspect, and had come to an opinion that it was somewhat in excess of the citys resources, and asked Mr Alexander to reconsider and modify the scheme. Meanwhile legislative authority had been granted for the right to take the water from the stream as a domestic supply for the city. The revised proposition from Deep Creek had been approved by the council and recommended to the ratepayers for adoption, and submitted to a poll and carried by an overwhelming majority on August 15, 1933. THE SCHEME DESCRIBED Giving an outline of the scheme, Cr Begg stated that Deep Creek, a branch of Deep Stream, with a catchment of 13 400 acres, had been tapped at an altitude of 2213 feet above sea level, and delivered by a pipe line generally 15 inches in diameter to Stoney Knowe at a height of 1146 feet above sea level. This was sufficiently high to command all three storage reservoirs and the whole of the residential areas in the city. Tenders had been called for the various works, including pipes, fittings, etc., the tender of Messrs Hume Steel Company, Ltd., being accepted for 36 miles of pipes down to Stoney Knowe. The whole of the pipe making bad been carried out in the city, and, as soon as pipes had been available, contracts had been let for excavating, pipe laying, the construction and erection of a steel bridge across the Taieri River, and other incidental works. The two miles and ahalf of pipes from Stoney Knowe to the Ross Creek control station are lapwelded steel pipes, manufactured in England. „ ~ _ "We have now before us, said Cr Begg, "a system that can be considerably developed. At the present we estimate to take 2,500,000 gallons per day from a catchment area of 13.400 acres, and we have at the back of it all 13,000,000 gallons to draw from a total catchment area of 40,600 acres, in addition to which there is ample room and facilities for future storage so that those who may follow after us need have no difficulty in duplicating or increasing the supply, as circumstances arise. Their problem should be less arduous than it has been to those of the present generation." ALMOST IDEAL Mr Alexander said that for many years the growing needs of the city had called for an augmentation of the water supply. By bringing in for the use of the citizens a supply from a source described by a competent authority as approaching the ideal, thp city entered on a new phase of improvement and progress. The old sources of supply from the catchments near the city would continue to be used, but their yield would be supplemented now by the water brought in as required by the new pipe line and later on by other pipe lines from Deep Creek or Deep Stream. Referring, to some ot the special features of the scheme, Mr Alexander stated that by the adoption of a high level intak in the Deep Creek, it had been made possible to carry the pipe line over a route which, while throughout its. greater part of comparatively easy access, was also at a fairly high altitude except for the crossings of the creeks and rivers en route It had been possible therefore to design the pipe line with comparatively thin walled and consequently low-cost pipes throughout a considerable part of the 36 miles between the intake and Stoney Knowe. The design incorporated provision for limiting the pressure to which the Dipes would be subjected This had been done by providing overflows, six in number, at suitable elevated points on the route. The effect of these overflows was that the pressure on the pipes above the overflows could not exceed the static pressure fixed by the overflow level. This arrangement had been an important factor in keeping the cost of the pipes down to a minimum.

The most important individual work subsidiary to the pipe line had been the Taieri River crossing. It had been originally intended to lay the pipes in a tunnel through the rock under the river but geological and geophysical investigations had proved that solid rock lay at a very great depth and was overlaid by massive detached blocks of schist and considerable depths of gravel. It had been accordingly decided to carry the 12in pipe across the river on a bridge designed to carry two such pipes so as to provide for future increase in the supply. The bridge was a steel arch, resting on massive concrete abutments. The pipe line entered the city boundary at a point bPlow Ashburn Hall. From this point the water was conveyed in a 12in lapwelded steel pipe line along Wakari road to the control station at Ross Creek reservoir. This lap-welded steel pipe is of different construction from that used on the other part of the line from Deep Creek. It had been manufactured in England, and was lined with a bitumen lining spun in by special process. The laying of this pipe had been carried out by departmental labour.

METHOD OF DISTRIBUTION The system of piping ana control valves incorporated the control and distribution of the water from Deep Creek and from Sullivan Dam. The arrangement of valves and by-passes was such that water from Sullivan Dam or from Deep Creek might be sent either into Ross Creek reservoir or up to Beta street reservoir in Roslvn - , .„ The by-passes are arranged, Mr Alexander explained, to connect the mains in such a way that any pipe might be used to discharge into any other pipe in the system, giving full command over distribution of the water. It would even be possible, if need arose, to send the Deep Creel', water back up the 14in mairt to Sullivan Dam. In addition to the discharge into the Ross Creek reservoir from the Deep Creek pipe, it was possible at Flagstaff Creek to divert the Deep Creek water into the Silverstream race leading to the southern reservoir It would be seen, therefore, that everv part of the existing system of storage and service reservoirs could be fed with Deep Creek water. The valve enabling the water from the pipe line to be discharged into the Ross Creek reservoir was then turned on by Cr Begg. assisted by Mrs Begg.

CONGRATULATIONS EXTENDED, Those present at the ceremony were conveyed to the Town Hall, where, after refreshments had been provided, congratulations on the completion of the scheme were extended to the City Council by the following:—-Messrs Newman R. Wilson (president of the Chamber of Commerce), J. W. Dove (chairman of the Otago Hospital Board), J. J. Marlow (Mayor of St. Kilda). T. Scollay (Mayor of Port Chalmers). C. Findlay (representing the Taieri County Council). A. Smith (Mayor of West Harbour), A. F. Quelch (Mayor of Mosgiel). T. M'Ahan (Mayor of Green Island), E. A. Ockenden (representing Hume Steel, Ltd.), J. Wilson (chairman of the Dunedin Fire Board) A. Campbell, M.P. 'Otago Harbour Board), and W. H. Shepherd (Otago Aero Club).