CITY SERVEYOR'S REPORT ON WATER EXTENSION.

Nelson Evening Mail, Volume XI, Issue 8, 10 January 1876, Page 4

CITY SERVEYOR'S REPORT ON WATER EXTENSION.

■ The following report was submitted to thai members of the City Council on Friday evening last :— :r To His Worship the Mayob , ; "and Gittj Council. Sir and, : Gentlemen— l have the honor to forward the: following report on proposed; Waterworks extensions, with estimates of the various costs thereto attached. 1 ' Aa it is highly necessary for an increased and more regular supply of water^ throughou t the whole of the town, I have considered several methodß ; for affording such supply, at a cost within , the limited, amount at the disposal pi the Council for that purpose. The first proposal which I made to the .Council some time ago as an expedient for a more regular supply, was to carry from the prpsent main water-pipe in Brook-street Valley, a seven-inch main ,acroßS the head of the town, to connect 'with the present main on the Waimearoad ■: also connecting it .with the present* mains in Collingwobd-Btreet, Tra-falgar-street, and Waimea-stseet. By such a plan a more regular supply of ."-water would be obtained by the residents throughout the higher parts of the town, and along the line of streets with which it would be connected, as it would pass over the highest point in Trafalgar-street, and would act as an additional reservoir at that height, but would not make much difference to the present irregular pressure throughout the lower parts of the town, which at present varies during the day from 601 be. . to 100 lbß. to the square inch, whereas the preEsure that could be obtained according to the height of the reservoir, is 13Q lbs. The cauie of sue!) variation in pressure is owing to the size of the mains becoming too small for thr number of house and other services at present Bnpplied from them.. Aa an example I of this,, l may state that the present i main pipe in Trafalgar-street is three inches in diameter, and there are between Bridge-atreet and Hardy-street fully forty house and other services supplied from it, the whole being equal to a five-inch pipe, supplied from the '. three-inch, main. It is therefore clear that in such a; street' the pressure must be very irregular, although not so much noticed where uaed for domestic purpoßes, as where it is used for motive 'power and for the extinction of fire. ■■ The main pipe in Bridge-street, although four inches in diameter, is even less equal to supply the demand with < regularity than the main in Trafalgarstreet, as it comes from the four-inch . main in Tasman-street, which also suplies the whole of the Wood. It must therefore be expected that with the present sizes of main-pipes, and the daily increasing supply, the pressure ; for motive power during the day must be very small, and a serviceable supply for the extinction of fires must be limited. There are at present several applications for the further extension of mains, which, if carried out without an increased size of maiu from the reservoir, will further reduce the pres- : iure, and almost entirely stop the eup:|)ly during summer to services at the i^leigbt even of the Hospital. I would Vecommend such extensions will afford no abundant ami regular

supply of water to all parts of the town, also an increased and regular pressure for motive power, from whioh a much greater revenue would be gained than at present, and also afford an abundant, supply for flushing drains and sewers^ which I consider ought frequently to be done as a sanitary measure, to remove all offensive matter that is at present allowed to accumulate. I would therefore propose the following extensions, which proposal I have already' submitted to his Worship the Mayor, who has expressed his opinion in favor of an extension, of which he has seen fcbe necessity for some time paßt. The extension that I propose would more than double the present supply, and give an abundance of water to all parts of the town for every purpose for which it may be required. First, I would recommend that an additional dam be constructed across the stream 5£ chains above the present, and 10 feet above its level, with a 10-incb supply pipe therefrom to the reservoir, in addition to the 7-inch supply pipe, which is too small to keep up a sufficient quantity of water during: the day to supply the present consumption. The additional dam and main 1 would give more than three times the present Bupply to the reservoir, which would at all times insure a rapid .stipply, the want of which has for some time been felt, more particularly during the late wet season, when it was impossible to store sufficient water in the! reservoir to keep up the supply without allowing discoloured water to run direct from the dam. The reason why such cannot be avoided at present is as follows : — That the; present pipe; as I have before stated, will not supply the reservoir during the day as fast as the reservoir has to supply; the town, in consequence ; of which at eight o'clock in the Evening it ia not more than twothirds full; therefore, should it commence to rain at that time sufficiently heavily to discolor the water at the dam it is at once' shut" off until it is again clear, before which the whole of the/water in the reservoir has been used, when the necessity arises for using the discolored water from the dam, which would -be avoided if the reservoir 'could be more rapidly filled, or it might be avoided by supplying the town direct from the dam, and keeping the reservoir (at all times full) for such an emergency. But this course is highly objectionable during the beat of summer. The want of a larger supply pipe from the dam has been felt for several years, but never so much as at present, there being fully double the quantity of water used during the present summer than during the summer of 1873 The want of increased facilities for collecting the water has also during the last two or three years given rise to fears of a failing in the supply during summer, which I may state are without the slightest . foundation, as there is at present water in the stream to supply more than five times the present consumption j the cause of auch alarm has been the want of additional means for collecting it. Second, I would recommend that a larger, or 10-inch main be laid from the reservoir down Brookstreet Valley to the line of Brougham-street, the area of which would be more than twice that of the present main, and the distance of such extension, 178 chains. I would also recommend that the present 7-inch main be taken up and relaid as follows — that a portion be taken from a junction at the termination of the 10-inch main in a direct line through ; . the Hon. N. Edwards' property to Brougham-street, thence in a direct line along Brougham-street to Trafalgar-street South, to its , termination; tbence down-Van Dieman's street direct to the Waimea 'Road, the distance of which is 75 chains. I would also recommend that the present 7-inch main. which terminates in Tasman-atreet at its junction with Nile-street be continued from thence as far as Bridge-street, thence down Bridge-street to Waimea-street, and from .'Bridge-street up Trafalgar-street to the Selwyn-street main. The present 3 and 4-inch main pipep which would be removed, I would, recommend should be used as future extension as follows:— To continue the' present main 6 chains higher up Washington Valley; to carry a. main up the Haven road to the new line of road on the face of the Hill at the back of the pilot station for a distance of 17 chains; to carry a main through New street from Trafalgar street to Collingwood street; to continue the present main in Trafalgar street as far as Halifax street; to continue the present main from the Waimea road up Hampden street to Kawai street, thence along Kawai street to Franklin street, thence down Franklin -street to Vanguard street. The various extensions I have therefore proposed, and the method of such extensions, will afford an abundant and regular supply to all parts of the town, including The Wood, whioh would take its supply from the 7-inch main in Tasmnn street. Such extensions will give an increased supply and pressure for the extinction of fire, and as it is now the only available source of supply for that purpose, it is a question that ought to be considered of some importance in the consideration of the proposed extensions. The estimate of cost for the proposed dam and 10 inch main from dam to reservoir, and from the reservoir to tbe proposed termination at the line of Brougham-street, including inlets and outlets to reservoir, all necessary sluice val?eß and fire-plugs, trench cutting

audl pige , layin* , complete, fa. £5,780 j the' coat of a 12-inch main in i'plaoe of 10 inch will bo £7,popj: t^jrofore; tli^ cost of a 10-inch maiu, added to the coat of present , gas-works extensions, will be £8,280, leaving a balance of about £1000. from theramounfc available^ for gas and water works extensions, for removing and relaying present mains as proposed. With- respect" tor the amount of revenue that 'would be derived from the proposed' 'expenditure on extensions they canopt; of coarse be expected to be reproductive for aomei considerable time, neither wba ld such extension^ at any future time, be so ,»4. once, a« it ■ cannot be expected that a sufficient number of oonsumerswOuld be waiting for water-service ori «omp!e» tion of the extensions to yield a sufficient revenue the 1 flret year. Ido not' expect that the revenue wising from, the extensions will be sufficient to meet the full interest on the cost for several years, which will be about £410' per annum, and the amount of revenue for the first year I estimate to be £100, the' revenue for the second £150,' and in- t creasing year by year. There would therefore be a loss on the expenditure for some years, but there would; at any time be a sufficient supply in readiness to meet more than three times the present consumption. The extension! would also afford other advantages already mentioned; which I think would fdlly compensate for 'the small amount of loss for a few years. I have the bopor to be, Sir and Gentlemen, Tour 'obedient servant, Wi LIGHTFOQT, City Surveyor & General Manager. of Public Worka. City Surveyor's Offlcej NeI«0B, January- 4 , ; 1876. ..