WATER, SUPPLY.

Wellington Independent, Volume XXVI, Issue 3160, 29 March 1871, Page 2

WATER, SUPPLY.

A. BPEOiit meetirig for tho consideration of this matter was held kit evenihg, at the chambers of the City Council. Present— Hia Worship the i Mayor, Messrs Mill*, Carpenter, Quin, and Plimmer. The' business of the meeting was opened by the Engineer being called npon to read his report, aa follow* :**^ , Rbpobt ok Pboposbd Watbb Supplt bob WEMIKaTON. -,- To : the Mayor ani> Cits Ooukoixiobbi,— . Gentlemen, — I hare the 'honor to submit for your consideration the fallowing report on a Water supply for this city :— I propose to tako the water from the Kai Warra Watra river, tapping it at a point near Baker's Hill, 410 feet above the sea level, and convey it into the distributing basin by a tunnel out for this purpose through the ridge that separates the stream from the Polhill gully. . '•'- Former schemes alluded fed in' my report of the 10th of October, 1870,. were, based on taking the'Bupply from this source; ■ 'With them, to far I agree, being of opinfoß; s after- oonsidera* tion and paying a due jregard to the funds likely to be procurable, that it is the only source worthy your present attention. - On reference to the plan accompanying this report, it will be seen that, irrespective of details, it differs from former suggestions in tho route of the- pipo ' track into the town ; .tho surrey showing clearly that rio difficulty exiits in selecting the shortest; line j its advantages I shall take further opportunity of alluding to. For the purpose of estimating the limit of any water supply tjtfcen from the point pro* poaed, the ridge line of the watershed haß been surveyed and found to enclose an available catchment area of about a square, mile in extent ; by no means oan thisbe considered large, though calculations, prove it to be ample and sufficient to meet the requirements of this city for many years. The course of the stream lies for the most part between precipitous bills of metamorphosed 'sandstone' formation, ranging from 700 feet to about 1600 feet above fcho sea level. The site presents favorable features for storing water, both as regards quantity and affecting quality, and at the point selected for the d»m the full width at top but little exceeds two chains in width, with, a vertioal depth to bed of stream of about 60 feet. This is not only favorable to economical construction, considered in connection with the quantity of water: impounded, but also favorable as. affecting tho stability of tho] dam. I may note here that rook crops up throughout the whole line of the oross section. In providing the supply for the town I pro* poeo to impound rainfall only, or, rather, nay rainfall on catchment and springs' yield, allow* ing a quantity equal to the. average summer How to pass on down the stream. By a series of observations, made with a three-feet weir to determine the average discharge of the stream due to springs, I find it to equal 310,000 gallons per diom, and of itself would suffice for a population of upwards of. ten thousand, with the large allowance of 30 gallons per head per diem. This could onlybe impounded by consent of the riparian proprietors heading to the reservoir, who probably would require compensation if the etreum were diverted. It ia this question of compensation, I consider, that will compel the Council, if it adopts any plan at all, to decide on forming a large storage reservoir with capacity equal to at least four months' demand, or to hold say 35,000,000 gallons as proposed. In estimating available rainfall it is usual for town supplies to baße calculations on the minimum fall in any one year. The absolute necessity of this is readily understood when it is considered that the nfexinmm demand and minimum supply ocour simultaneously, vis*, during the hottest and driest season. The following information regarding th# local rainfall has been taken from the valuable meteorological reports issued annually under authority of the General Government by Dr Heotor ; for the purposes under report it is indispensable. The observations were made at the Wellington Meteorological Observatory. . Minimum fall in inches per annum (lowest published statement) 41*95 during 1867 Mean fall in inohes per annum for previous four years 4463 Fall in inches per annum for 1868. ... 55*528 Mban bainfall in inches, and number of days on whioh rain fell for oaoh mouth, from 1864 to 1867 inoluiive (tabled in order of rainfall).

The foregoing figure* t show the rainfall of 1867 as being very low, and when compared with the average rainfall for previous four years, computed in 1868, and also. with that for the year 1868 we may safeij assume that the tniniraum rainfall stands at say 42 inches. The rainfall tabled in the monthly comparative statement is valuable information ; by it X am enabled to deteimine approximately capacity required for the impounding reservoir. In dealing with these figures- one thing to be considered is that the Wellington Observatory and the stream from which I propose to takftthesupply are several milea apart. No data in respeot to rainfall can be so acourato as the result of observations made on the site . of its intended application^ yet it is » unneeeasaryto alter the figures laid down as ;ths minimum rainfall, for the reason that ,th? quantity of rainfall on hilly duibpioM; syoh a§ the proposed oatohment ftl'most mr ambly •!• ceods the average fall.

o>BrgfarwrtTM-r-r ! - * .~n ' "ir mv •mm] - ...I ■niliTi .....a^f^J. tTfae quantity of water that can be collected and stored under conditions similar to those tinder report may be safely assumed to be j two-thirds of the annual rainfall, and in this instance would equal 28 inches. This in 640 aoroß would give an annual supply of 404,944,870 gallons, or per diem 1,109,438 gallons; whilst the demand, assuming a population of 5000, and an allowance of 30 gallons per head per diem, would bo daily 150,000 gallons, or annually 54,750,000. The proposed supply, therefore, taken in connection with the large daily allowance of 30 gallons per head, will suffice for a population of say 87,000. Thi3 amount is irrespective of the summer flow from springs, which, as before statod, equals 310,000 gallons per diem, and •would, if arrangements were mado to divert it with the riparian proprietors, supply an additional 10,000 inhabitants, malting in all a population of 47,000. Respecting quantity, therefore, no fear need be expressed. Before detailing the proposed works, I will enumerate a few particulars regarding the quality of the water. In the sumuier of 1870 samples were collected during a run of fine j weather, and were analysed at the Colonial Laboratory. Dr Hector's report runs thus : — " Both samples are of wholesome pure water, containing only a small proportion of organic matter. The fixed flalts were examined, and proved to be those usually present in spring and river waters. The following is tho quantity of ox'ganic and saline matters contained iv . a gallon of each : — A. B. Organic matter, with traceß of ammoniacal ealta ... 183 2*03 Fixed salts 989 9-13 11-22 11-16 Sample A I procured after a run of fine dry weather in tho neighborhood of nearly six ■weeks, nnd shows tho quality of the spring yield. Sample B was taken from the stream about seventy-two houra after a rainfall (continous and steady) of about one inch. Although tho totals in each case present but. slight difference, it will readily be noted that tho rainfall affected the sample marked B, ' by increasing the quantity of organic matter and ammoniacul salts, and on the other hand decreasing the fixed salts. The wacer when tested with soap makes lather freely. I tested it in this manner, and consider it but little inferior to rain water whitot for drinking purposes it ia superior. Begarding the proposed works, two wa;» present themselves j ono I would propose to follow in the event of satisfactory arrangements being made for diverting the stream, and the other if such course bo found pecuniarily impracticable. I base my report on the more expensive method, the former being simply a modification of the latter, and suitable only for the requirements of a few years. propose, then, to construct a dam, the central line of which on the crocs section of the stream would be about three chains up tho stream from the peg marked A on the plan. This'sito is exceedingly narrow', with rock as before stated cronping out on the whole lino of cross section. From this point upwards the stream, the ground widens out considerably, presenting favorable configuration for impounding a largo supply of water. Tho dam to be provided with conduit for pipes (supply mains and scouring pipe) and valve pit. A flood channel to be formed for" storm waters leaving the reservoir on the east Bide of the stream slightly in advanco of the dam conveying the storm water along the hill side and discharging it into the otream *bout two chains below peg at A. Below the point A, and a few feet above the bed of the stream, if; is proposed to drive a tunnel for conveying tho water through the range to a point near Bon the plan. This peg B is situated at tho head of a branch of Folhill's Gully and in close proximity to tho town. Tho length of proposed tunnel is under 1200 feet, aud presents no difficulties respecting cutting. In thi3 branch gully I propose to make a service reservoir, with capacity equal to say 600,000 gallons. Having examined the stream during floods, and found it much discolored, I intend this basin shall obviate t»ny annoyance by such discoloration, by supplying the town from it until the water ia the storage reservoir has had time to settle. I also propose with it to break the head of water considerably. In explanation of this I may state that the head of water if laid on from the storage reservoir would ba about; 450 feet above the level of Lambton quay, or equivalent to a pressure of 1951bs ppr square inch. This iv my opinion would tend to strain the mains unnecessarily, also tending to increased waste of water. The service basin would admit of tho head being reduced to about 300 feet above Lambton quay, giving a pressure on tho mains at this point of 130lbs per square inch. A junction could be made between the supply main and tbe storage reservoir to bo used only in case of urgent necessity, say fires in two or more parts of the city simultaneously, when possibly the extra pressure xnay be advantageously employed. From the service reservoir it is proposed to lead a twelve inch main down the gully, along the course of the Polhill stream, through the Town Bolt, To Arj street, Wordsworth street, into Willis street, along' which it runs as far as the junction with Ingestre street. At this point two eight-inch mains divergo, one continuing the line of Willis street and Lambton quay as far as Charlotte street ; the other down Ingestre street and Vivian street to Cambridge terrace, for the purpose of extending the supply southwards along tho Adelaide roud as circumstances demand. Six-inch mains are proposed for Charlotte otreeb and ftfolosworth street to the Tinakori road ; all other streets and terrace 3 North of Webb street t»nd West of Kent terrace to have six-inoh, five-inch, and three-inch as laid down on tho accompanying plan. | %By computation, tho eight-inch main would doliver on Lambton quay (all services closed), in six houra, about 320,000 gallons. I consider this ample, having before shown that 150,000 gallons represents the anticipated daily demand for several years. Sluice valves will be placed near street junctions to admit of tho water being cut off from any one etreeb during repairs or attach" ing services. Fire plugs will also be affixed on all mains at distances not exceeding in any case 100 yards. The following estimate has been prepared to show the probable cost of tho works as proposed. The cost of piping, respecting supply in Wellington, also trenching and laying, has been computed from prices paid by the Gas Company for such materials and work. It however, can only be considered as approximate until the details are more fully worked 1 out, though I believe the total amount as estimated will be found sufficient to meot all requirements. ESTIMATE. £ 8. d. Dam of Stone Reservoir, inclusive of Culvert Valve Pit, &<t 2162 0 0 Clearing site of Eeservoir ... 100 0 0 Storm Water Channel and Appendages ... ... ••• 1206 0 0 Tunnel ' ... 1150 0 0 Service Keservoir 1250 0 0 730 Tons of Piping, 200 Tiro Plugs, 54. valves (various) ; inclusive of trenching, laying and setting up' complete ... 8446 0 0 Cartage of Pipes and Sundries... 150 0 0 2 Street Hydrants and Hose, 2 setsofUpward's Patent Drills, complete 130 0 0 Land 500 0 0 Supervision, Contingencies, Sundries, &o 2264 0 0 £17,358 0 0 jfote; — Length of piping laid about 13$ miles — en ds turned and bored and prepared by Dr Angus Smith's process. Off this amount, upwards of £3000 may be deducted, and expenses to that amount deferred for several yeara if arrangements be effected for impounding and diverting the flow from * gprings.

Probably £12,000 would be expended the first twelvemonths, tho remainder during tho year following. The works as at present laid down to be i'ully completed within eighteen months, other extensions to be made as neceßeity demands. For the purpose of providing funda to carry out the proposed "work," I would advise that a Bill bo introduced into the General Assembly during the ensuing session. Such Bill, in addition to granting powers usually sought for in such Acts, to give authority to the Council for raising the sum of Twenty Thousand Poundß on the Becurity of the worka and rates chargeable for water supply nrder authority of the Act. It is for tho Council to decide whether power shall be sought for also to deoide such matters as amount of proposed loan, ratos to bo charged for water supply, &c. For its information I have collected the following : — Ander an Act granted by tho General Assembly of Victoria to the Municipal Council of Beech worth, the following rates are charged for water supply : — Load or part of o load of water taken from stundpipe, not exceeding 100 gallons, 1b 6d ; not exceeding 1000 gallons, lb per 100. Property rates for supply. Annual value not exceeding £50, 7 per cent ; 1 per cent additional for one W. C. or one bath. Annual value exceeding £50, but not £300, 6 per cent ; 1 per cent additional for one W. C. or one bath. Annual value exceeding £300, 5 per cent j 1 per cent additional for one W. C. or one bath. Power to rate hy Agreement. Domestic water supply not to include water olo«ets and baths, or for cattle, horeeg, steam, or water-power engines, washing carriages, or for hotel, tavern, trade, manufacture, bußinesa, or for watering gardens, or for fountains. With the siogle exception of an additional 6d per 100 gallons on the charges from standpipes, the same rates aro charged by the Bendigo Water Company, also under authority of an Act of the Generul Assembly of Victoria. The Melbourne rates aro as follows (taken from appendix B, bye- Jaws relating to sewerage and water supply, made 10th day of M B y, 1866) :— £10 anuual value and under 10s Aboye£lO do do do ... £100—5 per cent. ' Do. £100 do do do ... £300—4* do. Do. £300 do do do ... £500—4 do. Do. £500 do do do ... 3 do. and stores not being domiciles, 60s per contum on the valuation. Charges by measure unless by special agreement. Exceeding Not exceeding per quarter. 600,000 galls, Is per 1000 galls. 500,000 1,000,000 galls Is. per Ist 500,000 6d per excess. 1,000,000 9d per Ist 1,000,000 4£d per excess. In Dunedin, under authority of an act of the General Assembly of 1864,, th0 charges made are as follows : — On houses of £50 annual value, and under, a rate not exceeding on the valuation 7 per cent. Above £50, and under £300 6 per cent. On £300 and upwards ... &h per cent. Persons not applying for water to pay two. thirds of above ratoß. Power also is given to charge not exceeding £8 per annum for every water-cloßet or bath. In dealing with the question of water supply, tho Council must not overlook the fact that if ib be nob prepared or desirous of bringing wator into this city, it will be absolutely impossible to prevent some private company from so doing. Under suoh circumstances, tho logs to the city and ratepayers will be incalculable, as in a few years it would become inoro than self-supporting, and if economically carried out and administered, proride an annually increasing revenue to the oity. In the commencement of this report I alluded to the proposed route of the pipe track. The advantages of the track as laid down are as follows: — Ist. It leaves the line of the stream at tho foot of the dam, avoiding all ita sinuosities. 2ndly. The track is shorter than the Tinakori Road line by about three-quarters of a mile, no inconsiderable item as regards either first cost or maintenance. Srdly. It leads into tho heart ol the city by an almost direot line, allowing tho mains within the town to diverge both north and south, and diminish equally. 4thly. Fewer land-boldcra or agents to treat with. And, finally, if the track wore to lie along the Tinakori Road for the supply of the south end of the city, it would be necessary to do one of two things — either increase the size of the mains, or lay two, one to be used principally for this purpose. The latter course would be the best but probably more expensive. However, my endeavor has been to avoid either of these alternatives, by allowing an increased length of tunnel of about 300 feet. In October )&ab, by desire of His Worship the Mayor, I collected and forwarded to the Colonial Laboratory eighteen samples of water, with one or two exceptions taken from domestic supplies. By permission of the Hon. the Colonial Socretury careful analyses have been made, and the results tabled in an elabo rate report by Dr. Hector. This report, with its mass of information, will well repay peiusal. Having annexed it hereto, it completely relieves me from the necessity of bringing beforo the Council tho urgent need that exists for a pure water Bupply for domestic purposes. So much has been said and written regarding the want of water for Municipal sanitary purposes and fires, and also detailing tho benefits that would accrue from itß introduction, that I need nofc repeut or add to it ; it is to generally recognised that I opine few will be found, after the experiences of recent fireß, and the past summer, to put any obstacle (even bo little aa argument) in the way of Ita introduction. — I have, Sec, Nicholas Mabchant, City Surveyor. City Surveyor's Office, Council Chambers, Wellington, 27th March,. 1871. After reading his own report, Mr Marchant then read a report by Dr Hector on the same question. [We shall publish the report in our next.] The following resolution was put and carried unanimously by the Council : — "That the Council begs to return its thanks to Dr Hector for the very valuable report he has been kind enough to supply to tho Council on the question of ft water supply for this city." Councillor Mins could not think that Councillor Carpenter's assertion regarding public opinion on this question waa correct. Ho knew from peroonal experience of a great amount of sickness among, children owing simply to tho bad water in use in the city. He begged to move, — " That tho Council having heard the Engineer's report embodying a schema for the supplying of the city, with water expresses its approval of the suggestions contained therein, and that the assistance of a solicitor being required to prepare ft bill to be submitted to Parliament, resolves that Messrs Travers and Ollivier prepare and draft a bill for approval by the Council." This was agreed to. A resolution embodying a voto of thanks to Mr Marohant for his very able report on the subject was then proposed and cordially supported by the whole Council. Tho resolution was moved by Councillor Carpenter and aeconed by Councillor Quin. Counoillor Mitr.9 thon moved that the reporta of the Surveyor and Dr Hector be printed. This was agreed to. Councillor Plimmeb thon moved thafc tho Engineer be instructed to prepare the necessary plana^and data in order to onable the solicitors to prepare the bill for the water supply of the City. Agreed to. After some further discussion, it was agreed that his Worship should immediately aot upon Mr. Mill's motion. The Council then rose.

Month. Rainfall. No. of days. April ... 2*132 ... 6 March ... 2850 ... 6 :Ootober ... SI3O ... 11 February 3-280 ... 8 December 3-470 ... 11 'September 3*587 ... 18 November 3760 ... 12 Juno ... 4007 ... 13 August ... 4-022 ... 14 May ... 4-040 ... 11 January... 4*490 ... 10 -. (July ... 6*805 ... 14