CHRISTCHURCH WATER SUPPLY.

Star (Christchurch), Issue 3639, 9 December 1879, Page 3

CHRISTCHURCH WATER SUPPLY.

' The following report was read at" the 1 vity Council meeting last evening :— „ MR HUBBARD'S REPORT^X ':■'; " Hereford street Chambers, Hereford street, " Christchuroh, Dec. 1, 1879. - " Hia Worship the Mayor and -Membew City ■Council, Christohurch. >. :. .V; " Gentlemen,— ln accordance with instructions received to examine the proposed Source of supply at the Waimakariri, distant ; ;!lß miles from Christchuroh, at an elevation of •400 ft above Cathedral square,- and to furnish you with my opinion upon the same ; also, a reliable estimato of the cost of providing an effectual water supply for Chmtchurch therefrom, presuming the city to contain 50,000 inhabitants, I have now the honour to lay before you my report. Before entering upon matters connected with the source of supply in question, I wish to call your attention to certain acknowledged conditions which should be considered when adopting a source of supply for a city or town, and then to apply each of those conditions to the scheme under consideration. The conditions which influenco the selection of a source of water for the supply of a city or town are— "1. The quantity to be provided. "2. The quality of the water. , "3. The greater or less facilities for the economical extension of the works as a matter of construction. .(;'.! "4. Too avoiding, if possible, of mill streams, as tho compensation to be paid to mill owners may involve a large expenditure, particularly where a millowner. has power to impound tho water. "6. Whether the supply should bo con* stant or intermittent. "6. The relation between tho immediate and tho prospective financial conditions of the undertaking. "Application of Ist Condition to Paor posed Scheme fob Christchubcii. (" Quantity to be provided.) "Of tho gross population, it ia not always that the whole will tako water, the proportion of non-consumers to consumers will depend upon many circumstances— facilities for independent private supplies and the position of tho promoters of a scheme with regard to the town, that is — whether they are a simple trading company or the local authority itself legal competent to make bylaws concerning the use of water, and to levy general rates for the same. With regard to the former ciroumstance, Christohurch is at present, but with few exceptions in the north and northwest quarters, adequately supplied with water for domestic consumption by artesian tube wells, generally l£in diameter, driven to depths of from 80ft to 90ft, down to what is popularly known as tho first stratum of water, when it rise) to a few feet above the surface ; it has, however, to be pumped or carried to upper floors of buildings for use, for extinguishing fires, and all other purposes where pressure is required. Each individual householder can obtain a supply at a cost of from £4 to £8, according to circumstances. It is now also an established fact that a second stratum of water exists at a depth of nearly 200 ft, but the great cost incurred in dririDg pipes to this depth renders it prohibitive to the generality of private individuals. .. Notwithstanding the above facts, it is very evident to me. at least, from extensive observations made during the past five years,- that the wells are rapidly and signally failing, and that to a very serious extent, the flows obtained from well 1 ? B'ink now beiDg very indifferent to those of five years since. If tho City Council possessed tho power to control the great waste now taking place, I have no doubt that, in timo, the pressure would materially improve, but, as this power can scarcely be hoped for, and as the number of wells increase, and tho great waste continues, I fear it will not be many years before tho water will fail to rise to tho surface, and that for some considerable timo (until the pressure bo restored) the inhabitants will then be at serious inconvenience, if no other source of supply be obtainable. With regard to the position of the promoters of a scheme. — The proposed supply being in tho hands of the local authorities, competent to levy a general rate, it is reasonable to expect that at leaßt all new houses will take the supply offered by the proposed scheme,' with, tho advantages of high pressure. Therefore, under the circumstances, I am of opinion that it could not bo deemed wise to lay out a system of waterworks for Christchuroh without a view to tho whole population being ultimately included amongst the consumers. The natural base of an estimate of the required quantity is the population of tho district which wo will suppose is known with sufficient accuracy for the purpose. Guided by carefully assumed or observed rates of increase, it will be necessary in most cases to caloulato upon the probable population of some years honoo. I proposo in this oaeo, however, to simply support tho views of tho Council in fixing the extent of tho proposed scheme to a supply for Ohristchnrch as being likely to contain 50,000 inhabitants, based upon the following calculation, that the City of Christchurch contains an area of 1079 acres .within the portion cast of the Domain at coloured on the accompanying plan. It is usual to allow 47 people por acre in towns, therefore 1079 acres multiplied by 47 gives a population of 50,713. It will bo seen that the Council lia9 not over-estimated the future, possible and probable population upon tho area proposed to be suppliod, and upon which all my calculations are based. I am also of opinion that it would be very unwise to provido a scheme for any less number of people, especially from the source of supply under consideration, owing to its distance from Christchurch in necessitating an expensive conduit which can be laid at first, to meet the demands of the future population at a far less cost than two separate conduits of small dimensions, tho socond of whioh to bo laid whon required for extension. In calculating the quantity to bo provided for. domestic consumption and trade purposes, &c, I have estimated at 20 gallons per head por day for 50,000 people, which to some may appear a low estimate, put which I can front, experience provo is sufficient for all purposes, provided proper steps be taken for tho prevention of waste. The consumption at the present tim,e in Liverpool, a watercloset town containing 672,000 people, on the constant system, where the same measures are taken to prevent waste as I recommend to be adopted for Christchurch, is now only 14 gallons por hood por day for domestio purposes, including all waste, and seven gallons por head per day for trade purposes, making a total of 21 gallons per head ; it must be remembered, also, that Liverpool is a largo manufacturing town, which requires as much as seven gallons por hoad per day for this purpose. Carlisle, another watercloset city, requires only 20 gallons per head per day. Canterbury, also a wator-closet city, requires only 18 gallons per head, and many others are known to m,e where tho consumption for all purposes does not execod 20 gallons por head per day. In addition to tho above I recommend an independent fire-extinction service at all times in reserve, capable of throwing -jets varying in height from 60 to 80ft during any time, day or night, whether domestic consumption or for trade purposes is taking place or not, sufficient in quantity for ton jdts of 150 gallons each per minute, or a,, total, quantity of 1500 gallons por minute, jriakini r a total quantity as follows :— ' " ', Gallpna " For domestic consumption, trada and public purposes for 50,000/," w . ■ inhabitants at 20 gallons per ; .-.■ head per day ... .... „,..;..■ 1,000,000 "As it has been proved upon aovoraloocaBions that the greater portion of the, water is, consumed during the first fivo hotirs of tho day, between 6 and 11 a.m., it is usual to estimate that one-half tho quantity ito bo provided must,b.e.capable.of deliver/ during the aboyo five hours\as follows Y-T7 |'| / ' 1,000,000 gallons in tours "" "" , 500,b00; : „ 5 „ - 100,000 „ 1 „ . i, 1,666 \ !».y ; per minute. "Thoreforo the totall. quantity to be delivered per minute will; bo— Gallons • .. '. '■ .'■;::'■: ■■■.!'. pormin. " For domestic consumption, trade, and publio purposes •., 1G66 " For fire prevention 1500 "Total „. 3166 Condition No. 2. •f- ■ (Quality pf the water.) -, i " The water propose^ to\ jjfo supplied^'to OhristohurcKfrom the sourco selectedVull that^c(>uld, be desired, for a, po^ablo watori it ne^as up; arUfipiallpurification, it being

naturally- filtered m passing c through tho clea^eiog media of sand and. gravel stone. A samrile of the water has undergone a chemical analysis at the hands of Professor Bickerton, ana iprovea to bo an?exce]\entVaterfoV6U purppseg. I would, howeVer, recomuiend.'if tms scheme be carried, out, that the actionof ■W« water upon lead and galvanised iron be' ascertained, and that experiments, be made »V early as possiblo ao as to subject each material to . a crucial test, in order to determine, •waioh will be the better material ■ to adopt for the house services. Tho temperature.of «" water iss3deg, and ..would be delivered 11, temperature ; winter and summer alike,, as it would enter' the main and distributing pipes direct from the underground source, and so roach the consumers without being exposed to the influences of the atraoaphere for one moment, which is a priceless" boon, and one which in most other sources of supply can. .only be obtained by very expensive arrangements. The water having passed through tho oleansing media by percolation has been rondered pure and bright and well aerated, and attained the mean temperature of tho atmosphero for the year, and becom» of admirable quality, characterised— Ist. By being at all times tho normal and useful temperature of 53deg Foh , or 16 degrees colder in the summer and 16 degrees warmer in the winter than ordinary river water. 2nd. By being clear, colourless, and bright, and not affected by the heaviest rains or the longesfdrought. 3rd. By being freo from living or dead organisms of any kind, and from all organic mattor, animal or vegetable. 4. By being well aerated and fresh, and by holding a large proportion of air and oxygen gas in solution, and by being pleasant and refreshing to the taste. The normal temperature of tho water being thus maintained, at least in a great degree, when delivered into the houses of the consumers, the distributing pipes are not liable (a* with river water) to freeze and to burst in the winter, and the water is at all times pleasant to" drink. Condition No. 3. (The greater or less facilities for tho economical extension of the works as a matter of construction.) " Of all the conditions named, perhaps the most important is that relating to the facilities for extension for parts of some works, such as wel!s, reservoirs, filters, pumping i machinery, &c, additions may be made with great facility, while others, long conduits for instance, may offer serious or at least considerable difficulties if useless expenditure is to be avoided. So much is this the case that but very rarely are the several parts of a carefully studied system of waterworks porfectly harmonious at tho outset. In this oase when tho time arrives for a larger supply than 1666 gallons per minute for domestic consumption, the fire prevention quantity remaining constant, there will be no alternative but to lay down another main, for although a much larger quantity of water could be delivered by the main I re;ommend to be provided, it could not be delivered without destroying the pressure in reserve for fire extinction purposes. Ido not deem it necessary to provide a main at firat of greater capacity than one capable of delivering tho above quautity, as I am of opinion that it will be sufficient to meet the requirements of tho city and immediate suburbs, if needed, for the next 20 years. Condition No. 4. " (Relating to compensation to mill owners, . does not apply in this case.) Conditon No. 5. " (Should the supply bo upon the constant or intermittent system.) " Experience proves that undoubtedly the best system of supply is the constant, and should bo adopted wherever possible in the tru3 cense of the word, not by storing the water in cisterns large enough to hold all that the consumer may require in the 24 hours, and then to be resumed, for although this is in one senso a constant supply to the consumer, it is not constant Bervico by the water works, and U open to many serious objections, such as contamination by exposure, and failure to clear tho cisterns, loss or freshness, and temperature, &c. A constant supply is one in which the mnins and all other pipes of tho water works are constantly charged, and the consumer is at all times day and night able and at liberty to draw from them water for his legitimate use. It is not here necessary to enlarge further upon the desirability of a constant supply, or a Becond thought necessary to establish tho superiority of a continuous supply over the house storage system. Many objections worn formerly raised against the constant system owing to the great waste of water taking place, but valuablo improvements have of late years been mado with regard to tho fittings and method of checking waste, which will be described anon when dealing with tho question of distribution of the water, and which I recommend to be adoptod. Condition No. 6. (The relation between the immediate and tho prospective financial conditions of the undertaking.) " In this case, where the local authorities will have power to levy a general rate, it will simply resolve itself into what amount will be sufficient to provide for interest and sinking fund on loan. In calculating this, allowance must be made for revenue derivable from water power for machinery lam of opinion that, taking into consideration the present population of tho city, amounting to 13,000 possessing a very fair domestic consumption supply already, it would be porfectly mfc to recommend that, for the next 15 years a» least (notwithstanding all new housos may take proposed high-pressure supplj), that ft proportion of thodomestio supply amounting to one-half of the quantity provided by this scheme, or as much say as 1000 gallons per minute, might bo sold for the purpose of driving machinery, which, at a very low estimate per horse-power obtained, would produce an income of at least £1500 per annum. At the same time full provision should be made for all interest whatever that may becomo duo until revenue is derivable from the works, say fifteen months after they are commenced. Having applied each of the forogoing conditions to tho scheme under consideration, I will now proceed to give my opinion upon tho source of supply selected by the Council, afterwards as to tho method I should recommoud for conveying and distributing tho water in : the . city, ana finally as to the total coit of tho undertaking. ' Ist. — SomioE of Suppiv. "The source of supply is situate 18 miles, in a north-westerly direction from Christ-, dhurch, at an elovation of 400 ft above tho dity, on the south bank of the river Waimakariri, where a trial cylinder, 3ft in diameter, has been sunk to, a depth of 25ft into the shinglo and water-bearing stratum. As you aro aware, on Oct. 21 last, tho yield of tho cylinder was tested, and 400 gallons pumped therefrom in 52secs, which oquals 661,600 gallons in 24 hours, or 461 gallons per minute. Boforp pumping, the level of the water stood at sft 3in from tho top of the cylinder, and when tho pump was throwing tho above quantity of 461 gallons per minute, the water level was lowered 4ft in lmin lOaee, or a depth of Oft 3in from top of cylinder, at which lovel it remained whilst tho discharge kept constant. Immediately tho pump was tho wator again rose almost instantly to its normal level pf sfl 3in from the top of tiio cylindor. It will be remembered that on (ho previous occasion of testing the yield; of the cylinder, the river wus running within ft' chain or so of it, at which timn the water itood at 3ft 3m from the top. On Oct. 21, upon tho second occasion of testing the yiold, the river was found to have shifted its bed to a distanco of 15 chains from the cylinder, and the, water level was 2fb lower . in it, clearly indicating that tho level of the water in the, cylinder was influenced by the position of tho flow of water in tho river bed adjoining, the pressure, of the water when running netrer tho cylinder would cause the water to riso to p. higher, level in, it than when remove^, to some distance off, when the lino of saturation Equally falling. whore the ijiver.is flowing, pressure : w.oulti be considerably less, thuß unting for* thfllower level , vp°n . the pecond;,;,;QCca9ion._ ..On, -.Oct.. 28 last I again yjsited ; tho. j proposed ,ai to for. the intake works,*- ftjeo, tti? ■Burrounding : country. <I( l e.xamjn<!dj tjiflnloyel ( of, >$# wafar in fctie. joyjinder, and. found it.to .bo.tnesamo as .upon Pet, $lj and ; »)opoBition pit the flowing river) ,» he, [ same,. , r J,-als.o J ispok;;tho jd'iffeije.npe ,ot, [ ,tbe lovol between the top, water in.. cylipdor and; jtho.'i^tiep /flowing : : in .JhpMiaYpr^lS, eba.hiß ,di :i taflt, i I found, ffeo.wofserin.libo fljjtkderjtp, bo 4.ooft* loMrMvp '&&:,<>& .$l)6 riyor, whjclj), together with tho reaßonßjlJbaiY.o given .for ,|h/j difference of -level ,-in $ho, ■. oy Under occ^.rdjng jto tho pVsiliohpj&^the tiyorj'clepl^indlojßtoß ( that tho source 0$ $upply, \* no ofclier thari'tho wa ]°i' jM^V^t-uroteßj'jt^rougb ,$p ..shinglotbed from the flowing river atyng its courso, jWliicK is ■' cohtinuitfly ifowiMg 1 Mcfcrground'in jthtf direction' followo'd' By tho wattfr flowing on; [top, or at right angles to tho level contours 1 of th9'BUrfac»i spreading onf/uride ! r{»round utori 'each .baftlfjtfwitig tbtHo'toki'natai'ooftho

eningle. There can be no doubt that the quantity, r^uired can be obtained, or even a much larger^quantity, when necessary, but before I could offer any opinion as to the pre.cise number of oylhtdors, or whether one large cylinder sunk to a greater depth would be sufficient, I .should require to make some "further 'experiments before preparing any detail for. the intake works, to ensure the water remaining at a permanent level in the cylinder, when not only.the quantity required would be passing down the main, but to provide also for a ; : inu'oh larger quantity than required, for future. extension, the, extraction of which larger' quantity,. would have some considerable influence upon Iho permanent level of the water in the cjlinder. which is a matter, for very serious consideration, as the main, .when, fixed, cannot adapt itself to any alteration in the level of the water in the cylinder, or other intakes works lhat might J?e_._ designed. I hare, however, allowed a liberal sum in the estimated cost of the works, which, in my opinion, will cover the expense of the necessary work 9. With regard to the surroundings of the site selected, and the probable shifting of the river, which no doubt it will do every fresh tbab takes place, I am of opinion that it cannot materially alter its course, between the gorge and the site of. intake' works, as the, geological formation remains the same throughout its course, and the topographical features of the district from the gorge up to the site selected are favourable to my opinion. PROPO3BD KETnOD OF CONVBIINO AND DIS-' TBIBUTING THE "WATEB IN CHBIBTCHCBCII. " I would recommend the laying of a main pipe from the intake works, past the Miners' Arms, through Courtenayand Riccarton, to* the city, a distance of 18 miles, of cast-iron socket pipes, 24 internal' diameter, of different thicknesses, to withstand the various pressures due to an average fall, as follows : — From 18 miles to li\ miles, equal to 3J _ miles, averaging 28ft per milo, or 75ft From 14i miles' to 9| milos, equal to 4J milos. averaging 29ffc per milo, or 120 ft From 9J miles to 3i miles, equal to 6J miles, averaging 27ft per mile, or 167 ft From 3J miles to 0 miles, equal to 3J miles, averaging 12-Bffc per mile, or 38ffc i«T fl T j tfll ~ lBa V les ' 1 find on reference to Doyne's contour map, that the height at the site selected would be 420 ft above Cathedral square, and the barometrical levels taken by myself show 412 ft. Tne former, of course, would be the more correct ; therefore my calculations, based upon an available head of 400 ft, would ensure satisfactory results in practice. I would recommend pipes with turned and bored joints. They can be laid with greater rapidity and at less cost than can pipes with lead joints. Turned and bored joints require no lead, but joints are simply coated with a thin coat of Portland ocinent, and one pipe fitted into the other, every second pipe of the larger sizes being used to drive the preceding one close home into the socket, the smaller sizes being driven home, with a mall, tho special castings and bends to be jointed with lead only. A meter should be fixed at the mouth of tho intake with a sluice cook, in order to regulate the quantity to the requirements of the city as the demand increases. DISTBIBUTING PIPB3, H7.DBANT3, EIO., IN THE OITT. " I have calculated the necessary diameters of pipes to be laid in each street, so as to secure the number of fire jets at various places as indicated upon the accompanying plan, which shows tho boundary lino up to which 10-80 ft jets could be obtainable ; all within tho part coloured purple could bo commanded by ,that number of jets, tho boundary line being the river on the west and north sides, on the east by Madras street, on tho south by midway betwoen Tuam and St. Asaph streets. The part oolourcd light brown represents that part of the city which could be commanded by 8-6 Oft jet?, tho boundaries being on tho north by Salisbury street, on the east by Barbadoeß street, on the west by Antigua street and Park terraco, and on the south by South town belt. Tho part coloured green represents that part of the city which can be commanded at the extremity of the boundary by 5-6 Oft jets, tho boundary line on the north being the North belt, and on the east by the East belt. In addition to tho above it will bo observed I have provided imams of sufficient capacity to be ultimately extended to all the populous districts, including Papaniu, St. Albans, Bingsland on to New Brighton, Linwood, Ferry road, on to Sumner, Opawa, Sydonham and Addington, along which and at tho extremities of which mains it will bo seen eight 80ft jets can be obtained. I havo also provided for eight 80ft jets all along the South bolt by the railway, where largd warehouses aro being orected. Hydrants aro placed three chains or 198 ft apart in every direction, as represented by pink circles on the plan, where by the aid of a stand pipe having four way outlets, that number of lengths of Fire Brigade hose, each 200 ft in length, can be attached at any of tho hydrants, bo that if ton jets aro necessary to bo brought into play three stand pipes and ten lengths of hose will be required, four lengths being attached to one hydrant, four lengths to the adjoining hydrant on tho one eide of this, and two lengths on the adjoining hydrant upon the other sido of it j thus tho ten lengths of hose could be brought to play upon any house or building in the very interior of any of the blocks. The description o£ hydrant 1 should recommend to bo used is that known as Patterson's 4-inch hydrant, at a cost of about £4 each in London. They are tho cheapest and most efficacious. They aro opened by means of a horizontal slide ; tho process of opening is quick, and tho waterway is clear. PBESSTTBB EKDUOBR. " I should also rocommond a Deacon's Automatic Eeducing Valvo to be fixed upon the main in Cathedral square, so as to command tho whole city, and reduce ihe high pressure at such limes as it is not absolutely needed, a great saving, both "in consumption of water and in wear and tear of fittings would bo effected. ■-' > -■- WASTB PBBVKNTBBS . " I rocommond the oity to be divided into 20 districts.^ each one to comprise an equal area as possible; bo iU 'to contain whbn fully populated, 2500 persons to eaoh district/ each of which to ho suppliod through Differentiating Waste Water Meter, by which means .waste is readily detected, diagrams of tho quantity wasted being automatically drawn. Tho sating from the cause, oror and abovo that produced by ordinary inspection without the motors, is seldom less than 25, and is often 100 per cent. In Livorpbol the whole of the books aro kept, and the necessary oaloulations mado in connection with tbo waste water motor system, for a population of 672,000 persons, by mio clerk, whoso timo iB about half occupied in tho work. Tho distribution of the water, if carried out in accordance with my recommendations, would bo as pcrfoct as it" is possible to design it> and Christchurch would bo in possession of a fire prevention service superior to any city I know of, tho remotest part of which would bo , commanded by 5-60 ft jets, each playing 150 gallons per minute, or a total of 750 gallons por minute, whilst the moro 'important and closely built parts with high buildings would be commanded by 10 80ft jets of 150 gallons each, or a total of 1500 gallons, or. if two fires occurred at tho sumo tinle, 750 gallons per minute could bo thrown , upon each. With such a Bjatom of fire prevention ai this, insurances should bo granted at very low rates, which would make a very considerable reduction to the ratepayer's ,-. annual expense, jmd would jmak'o' the water rate scarcely worth mentioning ; moreover, with such protection, merchants and others would not doom it necessary to insuvo to tho extent they do at present. _ .... .... .... . .■ : j "ttOtfBE'BPRTIORS,y i " I have not inpjudod thp'co^tof laying any houso services, 48'itis^iifflcultr to pay what number woujd bo 'required for domestic purposes'for sonle' tmii to come. : * " " "COST." "I have gono veYy; catfetully into this matter/, ;and -, ; -Jry t ;amj of : /opinion; ■ that tho complete scheme, including engineering expensefltand .capitalising working oipensci, would pppt4U35,QQO. This, is by no moan| an extravagant amount -for a gravitation supply, wben.OB.tima.tod at per head of population; provided for,. viz., ( '50,00p v being. only £2 14s por,. head fur a supply of 20 gallons, perhead,,,. ; .; :j; i..,_ . „' ■:■_.. : .,.,,. i ',■■. „ ,V \, ! : ;[{ spveral 'gravitation supplies "in Ehglanci with! whiojijl ; ain,: acquainted, of, (^milar.^o,portions to thiqy-yizi, one million gallons -.per day for, domoßtic, consumption, for instance;

being from £2.t0 £2 }0i per head of popnlft. tion, so that tho proposed scheme catinot' be considered an expensive one by any means, more especially as the quantity provided to be delivered, including the reserve for fire! amounts to 4,459,000 gallons per day. I have only to say that it would occupj as least 15 months to complete the works from the time of ordering the pipes. "I have, &c., "W. F. HDBBARD, "Of Hubbard and Brown, • " Civil Engineers, .Sec, : "'■; ' "Ohristchurch."

, I ..,.,' ..,-.. ,-,,'J — r; — : ',''■.-' ' . '' .\'. ' ' x iffnxira'm* ■'• ' Cost 3 .<c Ai i. Popula. Constant Total .or Z6: tion. Daily Coat. <als pejfj ! .*■,,,■■)■■<■■') I -ir,.**. Sl »IW* . „ '. ■• hoad. I Atbtdn.'nndor : * ••■'•' > gallfrnn;^ • ■"•>.'• - i' , -.■Jtfna... ..,*« 70,673 1.00 D.000 _C 140,000 £3: IB 0 ? Blaokburn „/ C.1,000 1,490,000. 170.713 2 80* {■■ Jty&VtiC , ».< MW9 Uly%#x>. 100.000 '.g'.'ii <y ) ! ')«!The*Tertg6 Wit' of j^viMkm soheines ,'M'Wii •■.. Y.i'-jifU .-iUiV-.* '.'■'-■ '*'._ ".*'. ._..*'*>.': l