NELSON'S WATER SUPPLY.

Nelson Evening Mail, Volume XLII, Issue XLII, 12 February 1908, Page 2

NELSON'S WATER SUPPLY.

THE NEW RESERVOIR AND THE OLD. THE LEAK IN THE DAM. THE NEEDS OF THE FUTURE. A NEVER-FAILING SOURCE AVAILABLE. Yesterday afternoon representatives of the "Mail" visited the waterworks to ascertain the exact position jn regard to the city's water supply. The visit was undertaken in consequence of the reports as to the leakage through the wall of the dam, and of the deterioration in the quality of the water m the basin. It was found that half-a-dozen men had been put on to patch up the holes observed by the Mayor and Councillors on tho previous day. These holes are on the eastern side of the wall. The men were aLso engaged in digging a trench along the western side of the wall to ascertain if there were any cracks or holes there. Up to 1 o'clock only one slight crack had been exposed on this side, and from this there was only a drip. On the east side a facing of cement had covered some of the 13 holes seen by the Mayor and Councillors. But the water was pouring out of five or six holes in the wall, and the total quantity of water running out of the pipes fitted into the holes would fill probably a 3 or 4-inch pipe. This water was going absolutely to waste — down the Brook stream. One of the holes was large enough to admit the caretaker's arm up to the shoulder, and what the interior of the wall is like may be gathered from a little incident which occurred. While Mr Stone had his arm in the hole a piece of loose metal fell and cut his hand. Whether the water running out of the wall comes right through the wall or along it from the hillside on' the east remains to be proved. There has always been a leak from the hill, but it is hard to believe that such a volume of water as is running out of the holes could find its way along the middle of the wall. If the assumption be correct that the water is from the hill-side, then there must be a regular water-course in the wall, and for a third of its length. The cracks and holes being on the outside of the wall, the work of repairing will be difficult, for with the water constantly running the concrete will not have a chance to set, but will probably be ' washed away by the pressure of the water. A further perusal of this article may demonstrate that, expensive repairs at the dam need not be considered, in view of the never-failing supply that might be obtained higher up at a small expenditure — from a localtiy probably never yet visited by the City Council or City Councillors. At the time of- the visit the water was 4ft, 11 in below the overflow, there having b?en a drop of l_in in the preceding 24 hours. At the "wall the dam is 30f c deep, so that there was still about 26ft of water in the dam. Having expressed a desire to see the upper dam, the party were requested to jump into the caretaker's boat. The feat of getting into the boat is one calling for not a little athletic ability — and agility;, and when it is attempted by "the Mayor" and some of the Councillors who are in the mind's eye while writing, it is to be hoped that a cinematograph man will he handy. Safely seated in the boat one of the party appropriated the two cars, and the craft went skimming across the dirty, slimy expanse of water. At the upper dam the water was in striking contrast with that in the lower dam. A pin dropped into the water could b? plainly seen on the bottom, whereas in the big dam it was not possibly to see beneath the surface. Very little water could be seen running into the upper dam, but the part}' were assured that jx good flow could be seen hiirher up the gorge, so the journey, was icn'inued. Very soon a good body of water was observed, and about 1000 yards above the lower dam there was a flow of water sufficient to fill a 15-in 1 pipe. Tile whole of this water finds its way into the upper and lower dams, and if it were not for the holes in the wall i of the latter, there would doubtless be i an overflow. As it is, at least a 15-in pipe supply is running in, but the drain of a 12-in pipe is gradually lowering the depth of the water in the dam. This gives roughly a 3-in pipe leakage. , It is at this spot, a few hundred yards above the upper dam, that one realises the folly of the city having incurred the expenditure on the new dam, a huge "white elephant." Had the Councillors of the day journeyed a shoit diftance up the gorge il cannot 1 bo conceived that they would ever have sanctioned the scheme embodying the new dam Mr Jickell, then City Engineer, submitt?d alternative schemes for an improved water service, and one of them provided for small dams above the, upper dam. Beyond doubt this was the scheme that should have been adopted. Less than half a mile above the upper dam, the water .could b? impounded at small cost. There is solid rock on each side of the goi'irc rising to a height of between 50 and 60 feet, and all that would be required would be a wa'l across the gorge. From here there would be a fall of over 500 feet to sea level — a fall twice as great as that from the new dam. Here comes in the question of whether another dam is needed at all. Seven or eight springs give the city its w.iter supply, and these havo never be?n known to give out. Speaking from 40 years' experience, Mr Stone, the caretaker, states emphatically that the quantity of water coming from the springs has naver been less than it now is. Therefore, if the minimum flow for 40 years has been sufficient to fill a 15---mch pipe — and it must be remembered lb-it the present is one of the longest p-iiods of drought experienced — the question may well arise : Is a - dam higher up the gorge necessary? It appears to us as h.ymen that the laying of ibout half a mije of 12-inch pipes is all ihat is requited, a dam at the sQoft level h ing UKn.ciTSS..ry. If i(, was thought desirable U' have storage, the present upoer dam cou'd be retained, There is no desire lo create a scaro, but a visit to the dam convinced one that the water now being drawn for household purposes should be used with the greatest care, aud for drinking should first be builecl. The walls of the dam are covered with thick green slime, and the same stuff is floating over the surface of the dam. Further up the gi rge the trouble would not be met, and an ample supply of clear sparkling water could be obtained throughout the year. As the Council is holding a special meeting to consider the water question, it would be a good thing if the Councillors again visited the reservoir and journeyed half a mile up the gorge, Thpy would then see for themselves the easp with which a vastly improved water supply could be secured, and for a small expenditure. From this new. source, too, the water would be of excellent quality — totally different from that in the present big dam, and which the sun strikes all day, causing, from the large area exposed, considerable evaporation, and rendering the water sluggish. There can be but little aeration, the intake being to such a basin insufficient to give thorough aeration. Thes.e art? all troubles that would disappear further up the gorge, — where there is no green slime, where the sun strikes for only an hour or 'wo daily, and where there would be complete aeration. Before returning to favin the party inspected the water meter — "that' water meter which has been fbe cause of no end of criticism and abuse, and which has been widely credited with having caused a decrease in the pressure of water in the mains. Of late, however, not nearly so much has been heard of this supposed decrease, there being a better understanding of the Venturi system by whirih the meter is operated. Anyone inspecting the meter and having the principle' explained to him cannot but conclude that- Jjhe pressure is not ii> the Jpast interfered with. But the meter is a perfect little tell-tale. A chart is placed on a oylinder each day, and on the chart is recorded the quantity of water which passes through the meter and into the mains. And some queer disclosures the chart makes ! For instance, it came as a great surprise to learn that I approximately 22,0QQ gallons of water an hour are drawn from the mains from, roughly, 9 p.m. to 6 a.m. Totalled up this comes to close on 200,000 gallons of water used while the populace is in the land of dreams, and it makes •tig hole in the average daily record ■ *f between 600,000 and 700,000 gallons. „This is proof positive that there is an enormous use 'of water in prohibited t hours. The filling of the tanks on the. . higher levels, or the reservoir at the j Mental Hospital, or the household sup- j i

ply needed in the night, would account ' for only a fraction of this great quantity of water. Where, then, does it go Tho only conclusion that can be come to is that a number of people are smart enough to escape the vigilance of the water inspection, and allow their taps to run the night through irrigating gardens and lawns — stealing the water, in fact, just as common thieves steal other things. During the day and up to 7 p.m. there is a consumption of about 33,000 gallons of water an hour. At 7 o'clock, when hosing time has arrived, the chart indicates that there is a very free use of tile privilege, for during the hour that the hose may be used, the chart jumps up to the 50,000 gallon mark. The meter has been called a telltale. It tattled on Monday nigbt. A Jew minutes after 11 o'clock there was a sudden abnormal increase in the consumption, and judging' from the record on the chart a big supply was drawn, not from an ordinary service pipe, but from something much larger. The record popped up to a degree indicating that a 3-inch supply was being drawn. What a find for the water inspector if he managed to locate the spot ! Then, too, every filling of the water-cart can be followed. There is a sharp rise of the needle, and the red mark left on the chart shows that there has been an extraordinary draw on the mains. The hours for watering may be dodged — the water inspector may be dodged — but the water meter? You can't dodge it ! The conclusion arrived at by the "Mail" representatives, may bo summarised as follows: — 1. That an abundant and never-fail-ing supply of pure water is available for the city even without restriction of the reasonable use of the water for irrigation purposes, provided the sources higher than the present dam and old 1 reservoir be utilised. 2. That the expenditure of a relatively small sum will give the city a supply of the purest water, all that is required, temporarily, being the extension ' of the 12-inch pipes for a few hundred yards abova the upper dam. No fresh damming, or very" little, appears necessary. 3. That it is utterly useless, and a wast* of money, to tinker with the present big dam, except by way of precautions. Obviously tne present dam will be a constant source of expense now it has given signs of seepage, and it is a failure so far as giving an improved service is concerned. Therefore, the members of 'the City Council are urged, in the public interests, to visit the Gorge, and we feel sure that they will return from the visit with but only one opinion as to the best course to be adopted.