NELSON WATER SUPPLY

Nelson Evening Mail, Volume LXXII, 19 April 1939, Page 9

NELSON WATER SUPPLY

To Thp Editor •Sir.—All will bo grateful to thp Mayor for the information supplied in your issue of the 14th instant. According to recent stream gauging?, as carried out by the F.W.D.. everything appears to be planning out exactly as anticipated with regard to the throw ofT from the Roding and the Brook street streams: that is to say. we are told we can absolutely depend upon obtaining a minimum of something like .40 eusecs per square mile of drainage area, or say million gallons per day in the case of the Roding. This assumes of course that we are through hthe worst as regards the drought When money is being spent like water all over the country on large engineering schemes, it is well to take every possible precaution that our premises are correct. As a specialist by training in this particular branch of engineering. I have, during the last few vears, been urging caution: in other words, that we should look carefully before we leap. Water gaugings on an irregular stream channel, with current meter, tape, and foot-rule, are a rough and ready method, but unscientific, if accuracy is, aimed at. That two different observers, using the same instrument. on the same cross section of stream, should agree, as they apparently did. without about 9 per cent., proves only that their work was more or less correct, but not necessarily that their results were accurate. They know perfectly well that only an approximation was obtained, and would reply if questioned on the subject, that 'f more is required, let those that want it do the work and provide the necessary apparatus. Now I took the trouble, on 15th April to visit the Roding. and viewed the channel section where these gaugings were taken. There was a good discharge which has undoubtedly been well maintained during the last month or six weeks, showing that the water thrown off is now mainly deep seated. It appeared excellent water, and l brought back a sample When compared with my tap water it appeared slightly ’>arder when tested for soap U tr.fr. and it had a slight weedy taste and smell, only to be looked for in a dry weather stream channel full of sv’i rr pr growh and slime. I should t.ot say, at a guess, that there was more tl an 21 million gallons per day passing, out 1 may easily have underestimated the ; mount. For a few pounds, on this most excellent site, a notch gauge could be fixed that would settle this matter once and for all. It should have been done years ago. The proper way would be to make it permanent, but a temporary gauge plate, fixed with sand bags, a few bags of clay, and tightened up with bouldert- and sods of turf, could easily be made practically water tight. U is the only accurate way of making the test. A piece of iron plate, one-six-teenth :rch thick, is all that is required. mounted on boards to approximate to the rock surface. If this was sent out. the contractors, employing two men, could fix it up temporarily in two days, or permanently within 3 or 4 ac- \ MATTER OF HOURS ONLY . . ”1 had an important engagement on the Sunday night for which it was essential that my voice be in speaking trim and on the Friday I developed a cold. "By Saturday morning my voice was entirely gone. In resperaiion I purchased a bottle of Baxter's’ at 11.30 a.m. By 4 o'clock that afternoon, after frequent doses of your ’Baxter’s’ all huskiness, and tightnescs in the throat had disappeared, and my voice was back to normal. . . . Baxter’s Lung Preserver is certainly out on its own for colds and sore throats. . . .” Every day people testify to the efficacy of Baxter's Lung Preserver. Always take “Baxter’s” for coughs, colds, and sore throats. A few doses of "Baxter's” bring speedy relief, while the tonic action of New Zealand’s most famous cough remedy helps restore health and strength. "Baxter's” is pleasant to take —is ideal for children adults, and old people. Be sure it’s "Baxter’s”—l 6. 2/6. and 4 6. all chemists and stores.

cording to the number employed. Men living on the spot would keep a daily record of the depth over the cill, which is all that is required. The cost including cartage, should not exceed a few pounds. It would be an absolute picnic for a few school boys working under direction. I have put up many I such, temporary and permanent, revelling in the fun ' f it. I should love to |do it again if my legs were less stiff. 1 Haphazard methods should be avoided j where possible, especially when one is spending other people's money Let me give a few further examples. On 7th December 193.3 our conditions of water supply were apparently so i bad that our City Engineer reported that vve might only expect 300.000 to ; 400.000 gallons per day from Brook | street, or say .20 cusecs per square mile of drainage area Now, during a much worse drought, we are assured by the P.W.D. engineers, that more than ! 700.000 gallons per day are passing from this source, or .43 cusecs per squjire ! mile. j It was mainiy on these figures of the : City Engineer that I based my calculations for the Roding discharge I assumed a minimum of 350.000 gallons and increased it by the ratio of the size of the two drainage areas, obtaining roughly 2.000.000 gallons per day, or 20 cusecs minimum per square mile of drainage area. I had nothing else

to go on except general knowledge of conditions in other countries. Apparently the City is now taking about 900.000 gallons per day. Of this we are told that Brook street supplies 400.000 (as tested by meter) to the upper levels, and the balance of 500.000 is pumped from the Maitai for the lower the big dam being cut out altogether owing to the bad state of the water. Now the City Engineer told us recently that the Hanbv Park pumps were only capable of discharging 12.000 gallons per hour, or 288.000 gallons per day. The balance of 212.000 must therefore coming from Normanby Bridge. The truth is that with these centrifugal pumps, working against a varying head —dependent upon the draw off in the reticulation —nobody can tell what they are doing, or even if any water is passing through them at all. They should of course be pumping into a service reservoir when the discharge would be constant and easily measured. A meter fixed on the outlet side would give the necessary information but would not be then necessary. It is all so extremely rudimentary especially under the simple and ideal conditions we have in Nelson. VVc have been so penalised by 50 years of restrictions, that we have grown to think them the natural order of things.

I have been manager and engineer of. two waterworks companies besides engineer t"o the Brisbane Board of Waterworks during one of the most severe droughts on record. I would not like to say that in no case were hosing restrictions ever imposed but I certainly never remember them being necessary. T suspect the same thing applies at present in most towns and cities in New Zealand—the drought notwithstanding. What we did was to re-washer leaky taps free of charge, and concentrate upon stopping all unnecessary waste in mains, services and fittings. It paid us handsomely to do so. Here fully half cur supply is probably going to waste, and the people are dragooned through the Law Courts if they are caught trying to save their cherished garden plots. We are told to provide our own service cisterns at our own cost, when one service reservoir, which would have equalised both pressure and supply, would have answered much the same purpose at infinitely less cost to the community.

Our City rates are going to soar, and the City Council appear to me to be emulating the Government in making a business of their trust, thereby strangling private enterprise, destroying initiative, and the development of character and self dependence among the people. At present during the worst drought on record, the Maitai gravel water, by far the purest and best obtainable. has saved us, but the lay out is so bad that although all our gardens are perishing or perished, there is actually some 300.000 gallons daily, or one third of our piesent total supply, accumulating daily in the reservoir from the upper weir which we can’t make use of. Curiously enough the Mayor told us that complete hosing restrictions have resulted in a saving of 300.000 gallons per day. I should like to know at what sacrifice in comfort, health, and money? Apparently the order would have been quite unnecessary had we been in a position to use the water, but in our need we have rushed to the Maitai gravels, even the doubtful water at Normanby Bridge, regardless of the extra cost in pumping. It is all brought about by an attempt to try and supply the City direct through trunk mains from storage reservoir and pumps, instead of indirectly through service reservoirs. Yet I fear we are going to do much the same thing in the case of *he Roding. The small tank on Britannia Heights contains less than 200.000 gallons, and can hardly be called a service reservoir, though it will undoubtedly serve the purpose of breaking down excessive head pressure. Isn’t there going to be a branch main serving direct through Bishopdale? Is it too late to save the situation? The Roding tunnel is now about one quarter through. If we complete it and turn it into a power proposition could we cut ourselves free from the Cobb.

I see that the City Council is taking up the matter of the delay in the Cobb scheme seriously. In that they are to be congratulated. Suppose we could average 800 horsepower daily from the Roding. would it pay interest on the capital expenditure in generating power and light? These are questions I should like answered.— I am, etc..

H. G. FOSTER-BARHAM. Nelson. 17th April.