A HIGH PRESSURE WATER SUPPLY.

Press, Volume LXIII, Issue 12824, 7 June 1907, Page 8

A HIGH PRESSURE WATER SUPPLY.

» — CHRISTCHURCH ARTESIANWELLS. (By Da. Chas. Chilton.) The eitizons of Christchurch are shortly to be asked to authorise a loan for the purpose of providing tho city with a high pi.t.-.uro water supply. Tho a mount required for this purpose—for Ihe various wards, Central, Linnvood, Si.. Albans and Sydenham—is abmit £125,000. Beforo any .such sum a.* this i.s i;x_M.*ink"il, it is d«isira.ble thai, very careful consiUtration should bo giv«:-n to tho C:ty Council's proposals. That the high iii-lis.sure water supply is highly elc..irablo tor domestic purposes, for i-aniiary n*.i_ons. and for the prevent ion of lires ks undoubted, and the only wonder us that Midi, a system has not been installed lonig ago. The very eat-- willi which tho t-ystuni could have been established appears to be really the reason why wo are still without it. lt may wem absurd for v layman to say anything on what ifi, a.lter all, a technical subject, but thore are bomo primary principles involved which appear to me* to lar to have boon overlooked, and 1 venture to endeavour to place them before t'.o citizens. for a water supply tho primary requioites aro:— 1. A esufiieieiit supply of wator. 2. Purification of tho water, if .uecostsary. 3. Conveyance of tho water from its source to tho con.Minners. ■1. Siihicieut pr..._ii_o of the water for tiro prevention purposes. Now, I vcmturo to sa_/ that our Chrk--tcliurc.il artiwian wator supply fulfil,, all tiie_o requirements except the bust, ami _iiueo ttw whew of Christchurch is utmo.t. on a level, no part boiaiig, 1 (suppose, more thau twentylive or thirty ieet. above any other, Uio t.-u-'k of ra'-.„ig tho prt_.-.u.*o of tho water to tho amount required should bo an excexx.iii___..y ea_y uue. Let u_ 1i.1.0 tliLoo pom it* in eider and _co how tJio hi'Cts btaiid. First as regards the supply of water, it will probably bo Deserted that the artesian supply is insuibcieut and uu-c.i-taiu. Sow our arte_ian supply come, iioni an underground stream of water, or racier from several underground streams at different depths which aro flowing from higher to low or levels between impervious or water-tight strata. These streams, in all piobabiiity, flow out under tho sea, bub their free escape at tho lower outlet is hindered by tho friction of,tho water in tho porous stratum, - and tho result is that the spaco between tho impervious strata 'becomes filled with water, and as mo know, the pressure of that water is sufficient to force it to the surfaco as soon as an artificial outlet is afforded by means of an artesian pipo. Theso underground streams, therefore, depend on the arrangements of the strata undornoath tho (Aty of Christchurch, and tho wator supplied to them depends, directly or indirectly, on the rainfall on the surrounding parts of the Canterbury Plains. These, fortunately, are things that can bo altered neither by City Council nor by engineer. They wore there long beforo Captain Cook ever sot his foot in Now Zealand, and they will remain there so long as tho plains and tho rainfall contmuo as they are. Thero is no doubt, therefore, as to the permanency of the supply, and that supply is thero waiting to be drawn upon constantly, summer and winter; whereas, in most cases, towns have to deI>end on a supply that is intermittent and great expenditure for storage is the* necessary. Bat is the supply sufficient? Let us take a few facts. I havo not myself been able to get particulars of all tho artesian wells in Christchurch, but fortunately in a report drawn up about four years ngo by tho Hon. H. F. Wigrara, then Mayor of Christchurch, I,havo sufficient for tho purpose. He tolls us that during tho year 1903 Mr J. Osborne, tho principal contractor for sinking theso wells, sank somo sixtysix wells, most of these to a depth of more than 200 ft. Particulars of tho flow from these wells were supplied to Mr Wigram, and he tells us that tho total flow from these sixty-six wells per minute was 2315 gallons. Now, I bolievo that tho proposals of tho City Council provide for a supply of only 20 gallons per head per day. This is manifestly insufficient; 50 gallons would probably bo an ample supply, but let us allow 100 gallons per head per day. Then these sixty-six wells are every minute supplying sufficient water for tho daily consumption of twentythroe persons. Multiply that by the nuniiier of minutes per hour, and the number of hours in tho day, and we find that thoso sixty-six wells, durinig the twenty-four hours supply sufficient water for tho consumption of about 33,000 people. Now, thoso are only the wells sunk during one year; probably during 1904 a similar number would bo sunk. In any caso, twice that number of wells would supply sufficient water for a population of over 00.000, which is more than the present population of Grenter Christchurch. If. then, we think of the whole number of wells that havo been sunk in f hristchiireh in tho last forty years, from all of which water is constantly flowing, is thero any doubt that we have there a supply abundantly sufficient for a town many times larger than its present size? During all these years wo havo been allowing privato individuals to sink well*, without restriction, to use the small amount they reqniro for their own purposes, probably far lc.s than one-tenth of tho wholo water from tbe well, and to waste all the remainder, yet even with this enormous- waste go int. on year after year, we have not.yet .suecoeelex. in very appreciably diminishing tho snpply fi-om our underground streams, though we have (-c-riounly dim in is lied the pressure of that supply. Further facts n-t to tho quantify aviilaWe should surely bo unnecc.-t-ary. but let us take another example. About two years a,g\ a certain well was sunk in Cliristchurch for the supply of a swimming bath. That well at first gave a flow of 170 gallons per minute, that is, 211,800 gallons per day. On the same basis of l(XI gallons per head per day. that pingle well, if tho flow remained undiminished, would Iy> sufficient for nearly 2500 potions, and a comparatively small number of such wells distributed over the area of Greater Cliristchurch woukl ho amply sufficient for the whole supply. Now I shall probably bo told that figures can be mado to prove anything. Lot mc, therefore, give some figures that have been put to the test, for which I am indebted to the courtesy of Mr William Go-a*. At his Canterbury Steam Sawmills, in Durham street, he has a well with a 3in bora to the 400 ft st return. Thidrives a Blake ram, delivering 784 gallons per hour, and from .*> p.m. until 8 a.m., this supply is distributed to the wholo of the block bounded by Durham, Colombo, Salisbury, and "Peterborough streets, containing about thir-ty-six tenements, and proves ample for tho persons supplied. If we allow, nay, four persons for each tenement, probably a low estimate, we hare that

one well, during only part of the twen-ty-lour houis, proviuing for tho requirements of about 150 persons, but that is only the amount pumped up by tho ram, probably only about one-fifth of the total supply trom the artesian. Consequently the well itself would probably c'.ipply some 750 persons, and if tho supply was continued during tho daytime, instead of being used _>_it i*> at present tor Mr Gosas uiillis, thero would bo -sufficient for, say, IUOU persons, and consequently only sixty biich wells would be required lor the whole of Gi eater Chris .church. Other tacts supplied ireiia other weba could Cii.sijy bo given, a.r.d uiey wul ai'i t.li tiie sa.rno tale. But if a.iyoi:_ .still thinks th-at aru_.i_u_> are n.-c supplying buiiicieiit water lor the ie(juaeiuente. of Unr_>.cuurch, k-D Imu i'.;..k at the condition of _ur street eh annuls. Thero ho will see n.il'i'.ons of galiuia. of water al***olir.e.ly mini in... t-j waste hour by hour and day by day. On the north side ot Worcester stivet w<Ast, from tho Museum to Cambridge terrace, tho channel is con&taai'tiy lull of water running at a rap.-d rate, k> rapidly that if tho grating at tho coiner oi" Worcester street- amd Cambridge terrace becoma. blocked with le.*„ vc_ there is in a very short timo . a perfect flood acro__ tho i_tiw.-t. Ihe tia.w thing is true evf tho part of Weircevsior street from Cathedral _t_uaro to the. Worcester street bridge. Iheie there is Mich a quantity cf water that tho original cliuuirl \v:i.s mot •sutncie-.it te> ceiutain it, anel the water was const.uuly flowing over Ln.to tho street, and tor very .slutinc about two yearn ago tho authorities had to form a deeper cliai_ul, and cover oveir tho top tvo that this watte of water might bo hidden, on tho principle that "out of sight is out of mind." But though unseen, that 6tream of water is still there, flowing _ silently and swiftly into tho river on ono side oi the bridge, whilo tho Tramway Board patiently pumps it up again into ita watering tanks on tho other side. The same thing is true, to a somewhat less degreo porhaps, of Hereford street and Gloucester street. These I mention because I am fa.m_.iar with them, but we have the sarnie waste going on in every street in Christchurch; everywhere the channels contain a copious stream of water—a glorious and refreshing sight in the heat of tho s-iitntner day wero it not for the fact that our eyies are blinded by the cloud's of dust which oaninot bo laid because, forsootih, our city authorities have not suffioionit water to water the streets. So much, then, for tho quantity of tho water supplied by our artesians. As to tlie purity, wo need say nothing. We only require to go to some other town in New Zealand, and try tho water supplied to theni, to appreciate the purity of our artesian water. Most towns, when they have got a supply d. water, havo to go to a grc.nt expense to purify it by various systems of filtering. We ore saved all that. Then, again, instead of having to convey our water for many miles, wo havo it right at our doors under our feet, positively asking us to consorve it, and make uso of it. But. even granting the truth of all this, I shall probably bo asked, how aro we going to stop this waste of water? How can wo interfere with any person's right to 6ink a well in his own ground, and mako what use ho pleases of tho water from it? That is a question for lawyers and legislators, and if the authorities havo at present no power to do it, it is high timo they got it. If the stream were one flowing on tho surface of the land, no ono would be allowed to uso the water to tho injury of his neighbour; strict regulations would doubtless bo made that anyone using tho water should return it to tho stream again. Is there any difference in principle between such a surface stream and an underground stream? The authorities already have power in many directions to prevent any one person performing acts that are likely to injure his neighbours. They can even prevent a person putting up advertisements that are likely to shock the .esthetic tastes of others. If they can do this, surely they can as readily get power to prevent this sinful wasto of water that should be the common property of all. In any case, whatever may bo done with tho present wells, immediate steps should bo taken to prevent any further wasto by the sinking of additional wells by private individuals. One waterbearing stratum, suy the one 400 feet below the surface, should bo absolutely taken over for municipal purposes. As tho water-bearing strata aro quito independent, tho shallower wells would not be affected, and could, if thought desirable, he left for privato uso aa at present. If this wero done, and a number of wells sunk at reasonable distances from one another, there would probably be still enough water supplied from theso wells for our whole requirements. It is important that theso wells should be scattered. If wo attempt to draw the whole supply from ono single large well, too great a drain is mado on the district immediately suri rounding tho well, and both the pressure and the quantify of water may be seriously lessened. With a number of wells at sufficient distances, the risk of this is very materially lessened, and the supply is proportionately greater. So far ii 3 the supply for purely domestic and sanitary purposes is concerned, there would, of course, bo no necessity for sinking fresh wells whatever, if we could only securo control of one well in each block, and supply the water from it to tho whole block as is now being done by Mr Goss to the block mentioned above. For fire prevention purposes, preater pressure is necessary. How that pressure is to bo obtained is, of course, a question for eiigifeors, but surely for a place lilo* Christchurch, where we hr>ve no high levels to bo supplied, the problem should he a very easy one. It may bo done by ererting water towers, as his already been done nt .Sydenham with. I understand, very satisfactory result., or, again, I am told, that it would be exceedingly easy by means of suitable pumps tti pump directly into the mains. a .ml obtain sufficient pressure in this way and if, as I havo sitgge.-.ted above, we could provide for the* domestic, requirements from existing wells, the supply for firo prevention purpose;- could bo kept separate, onel tho quantity required for it would reft be great. All that would ho nece«.--ary would be by means of pumping to keep that supply under sufficient pressure. Whatever is done, I tnut that there will bo no attempt made to build a rec-erroir in which to store the water. I understaml a proposal has been made to establish a reservoir on tho Port Hil'e*. That would in tho fiit-t place tv an alsclutely uiinecessary and u.se*l._ss expenditure, because it would .mean pumping the water away from the consumers, whore it is required, for tho purpose of letting it flow back again. But more? than this, in an open reservoir, our artesian water, at present unequalled in its purity, would be exposed to all the germs that blow atout in tho dust storms, of which we have so many, and we should i«ooii have growing in the water all sort, of obnoxious plants and animals, and the purity of our wator would bo lost. I am not speaking at random on this matter: I conld give examples of artesian water that has boon pxtkishxl in reservoirs until it has becoire fo cotitaminated with living organisms as to be positively undrinkable. In summing up this plea for tho con-w»rvat-ion and utilisation of cur artesian water supply, let mo give* an ana-«-'_y. Suppose we wanted to supply pas to all tlie inhabitants of Christchurch, and that we had in every person's -back yard a never-failing suppiy of natural gas, _, it likely that under those circumstanex*s we would go to the Malvern Hills for coal to make gas from, or even talk about estaWishin.;

a coal depot on the Port Hills. And yet proposals, exactly similar, are mado with regard to the water. We have the water at our doors, and people proposo to go to tho Waimakariri for it. or establish a reservoir On tho Port Hilt**. If there weie such a supply of ga<=, we woiihl not be lonj* in giving that gas the pressure required. Why cannot we do the same thing with the wator? There may be difficulties unknown to mc iv securing control of the water at prevent allowe-d to run to waste, or in giving that water sufficient pressure for lire prevention purposes, but until every effort has lx*-en made to ovoie.oiuo these difficulties if they exist, it seems alwuird to propose to spend £125,000 on a scheme that ignores the exceptional alvantages offered by tho water lying beneath our feet. _l>_ Hereford street, sth June, 1907.