THE SEWAGE QUESTION.

Otago Daily Times, Issue 4741, 28 April 1877, Page 1 (Supplement)

THE SEWAGE QUESTION.

THE CITY COEPOEATION. AND THE HABBOTJE .._■.■■-: .. ..,- : EOAED. . . -. ■■ At a recent meeting of the Harbour Board the Secretary and ■ Engineer were instructed to prepare a jfiemorandnm tc the Corporation of Dunedin on the subject of the Rattray street sewer, arid the Chairman of the Board was authorised to approve of it if he thought fit. . , . : - ■'" ■ ■ . . , ■ , ;.

The Chairman, although approving of the memorandum, thought it advisable to submit it to the meeting of the Board held on Thursday afternoon. "':".'■

The following is a copy of tho memorandum, which was ordered, to lie upon the table until ;bhe next meeting of the Baard,':— ; The' Otago Harbour Board, in view,of thei important questions arising out, of the discharge, of the.Eattray street sewer into, the.Steamers' basin, and of ,the proposals of the City Corporation te make the harbour the1 general receptacle for the.city sewage, is^ desirous that the subject should be well considered on a broad, basis, viz., as afftcting the best interests of. the public,; for whom both the .Corporation and the Board stand" equally in the position of trustees, amd: not. from the narrow one of how. ths decision thai may be arrived at may effect either the one body or the other in ita irsdividual interest 3- > The Board desires it to be, kept in reni<imbrance that whether moneys be expended by it or by the Corporation, it is tha. taxpayer who has to provide the sinews of war in both cases., Taking this view, it should be .the object of both-bodies to aid one another in conserving the public funds- and interests, and not to act so as to necessitate expenditure which might; te avoided did wiser! counsels prevail. The Board claims that! hitherto, it has acted' in accordance with these'views when dealing with any proposals, submitted to it by the Corporation. Refer-.' ence might be made to the application for occupying a.portion of the Board's endowment with a siding from the railway to the Gas Workß, whereby a large savirsg to the ratepayers was effected. The application to be allowed to remove, gravel and sand-from the beach at Pelichet Bay, near the mouth of the Water of Leith, to make footpaths for the citizens at a cheaper fate than could'be done otherwise, was at once granted, although the Board was aware that some thousands of cubic yards would be removed, which it would nave to replace,' in case of reclaiming its endowment, at a cost of 3s per.cubic yard. Sites have alsobeen granted, wiShin the Board's endowment, for depositing the city refuse and for public baths. In all these-cases the question of a. quid pro quo I: —to'use a familiar term—was; never raised, flimply because the Board felt. that the public ■ interest was really to be served by the ap plications being granted,';and therefore that in doing so it was fulfilling its. trust by not sticking for what, might have been fairly, claimed if only, looking to its individual interests from a mere monetary point of .view. Reference is ma'dfe, to these caaes for the purpose of illagtratm:,' tL'e principles on which • the Board has acted towards the Corporation, and of disabusing the minds oif those who. might otherwise have rashly,come to the conclusion that the Board, in opposing the discharge of the city sewage into tho har? bour, is, doing so from any narrow or merely peenniary motive.; It believed that in doing Bo.it is acting in the best interests of ;the publio.. .The grounds on which', the; Board has.based its conclusions are mainly two fold. —sanitary and pecuniary.'.-.- Jjirat,, and" of more importance to the oitizens andresidenta in the neighbourhood of !the beaches of the harbour, is the Banitary'aspect 'of the question, and in dealing with it the Board would ask the Corporation not to look at it merely in the light of the esJsting population of the city of Dunedin, but affectiiig future tioris,.when th^ : whole sides of., the,harbour will be thickly; populated.. Mr Simpson, the Board'sT'erigineer,;in Ms published report,, dated 16th. .Sugust,'lß7s, gave, his professional opinion^ which,, by-the way, has never been,.doubted on this point), as follows :—■ " The'sewage question, naturally "arises in treating upon harbour improvements, and I will here state that my opinion ia," a verse to permitting sewage "deposits to enter the bay.r My reasons are as follows:—The1 average duration of the ebb tide is about six hours, andthfl average surface velocity lginile per hour. The distance from Dunedin to the Heads is about; 13| miles^ Material from the sewers, if deposited in the harbour at .Dunedin at the commencement of the ebb, can only thus reach a distance of 10J miles— that is, three miles shbrt of the Headß. The sewerage must eventually be deposited .on the banks, after being carried backwards and forwards by the ebb and flood tides for probably a considerable period, and the greater portion of it on the sandbanks and beaches of the Upper Harbour, if the discharge ia incessant. The quantity of matter that would be discharged into the bay by the sewers cannot but bo considerable, although the' quantity need not so much be taken exception to as the effluvia that must be emitted from the deposits at low water, and it will not be readily admitted that the deodorant power of sea water is such as toT prevent the banks aud beaches from becoming unhealthy, and iosufferable nuisances hereafter.".:

There cannot be a doubt, then, as to the resnlt,,although it may take some time to make itself felt.- If sewage 13 permitted to be discharged into the harbour, the foundation and food for future nurseries of disease and pestilence will be well aad truly laid. Again, of what use will be the construction of bathß ? Are our citizens to find health in wallowing in water impregnated with all the filth and excrement of the city ? It is well known that it is now costing enormous sums to get rid of. the evils that have resulted from permitting sewage to flow into harbours far more open to the action of the ocean than Dunedin harbour is, in the older Hcme countries; and the Board believe it is correct in 3ta'icg that leading scientific men of late years have condemned the theory that salt aefs as a chemical deodoriser, holding that its action can only be regarded as a diffaser, the strength of the mixture depending entirely upon the proportions of its constituent parts. As early as 1861, before the beach immediately in front of the Government Offices was reclaimed, the effect of the deposit of Sftwage was acutely felt, and the late. Dr Hulme (see Appendix to session XIV., Votes and Proceedings of the Provincial Council) reported oil the subject by rf quest of his Honour the Superintendent. The following is an.ex|r_a3tfr>m his report;—,: ■

"Having, at yonr Honour's request, examined the cauae of the offensive effluvia' pervading the Government Offices, and emanating from the harbour beach, I have the honour to certify to the existence of a great alteration in the direction of the harbour sedimeut, which is caused by the extension of the jetty outwards, additions to its base,' and the interruption to the tidal way by numerous vessels moored alongside; whereby | sewerage matter, animal and vegetable subt starces from the town, arid refuse from the | vessels lying in the harbour, are deposited i nn the shore, principally ia front of the Go Vfcvnment Offices, there to be acted en at low water by the sun and air, and their decomposition accelerated by being worked up by carts going to and fro on the beach. This also greatly facilitates the escape of noxious gasea and volatile deleterious compounds, formed by the union of the elements.of decomposed sewerage rnatttr with which the muddy beach is saturated. The most notable of these compounds which I will mention are ' sulphuretted hydrogen gas' and ' hydro-sulphuret of ammonia,' which occasiou the nauseous smell, and are highly injurious to animal life and the well-being of the inhabitants of the city. Moreover, there are other elementary gases as well as compounds formed, which may not prove poisonous when much diluted with atmospheric air, yet are sufficiently irritating to the mucous membrane of tha eyes, nose, and re- ! spiratory organs, to become causes of disease."

The Board would further remind the Corporation that o important was this question deemed by c Provincial .Council, that a commission was appointed, which reported in 1865 on it. From the evidence attached to the report, the following extracts are given :—

'•'. Dr T. M. Hockeh's evidence

" Q. 17. —Do you think it would bs safe to carry the sewage of the town into the Bay immediately in front of the town ?

A.—la my opinion it .would be extremely unsafe,;, inasmuoh as I believe the ebb tide .would. merely carry it, two or. three miles down the Bay, and hot into the sea, and it wonld, if such were the case^ pattly.be returned with the flood tide.

"Q. 18.—-,Cau you give any : instances of towns becoming unhealthy, from :such a. cause? .... ' ■ • ~. ■■.. • ; ; ;

" A.—:lnstances of the kind are extremely numerous." . ~.,' . ' •. . ... ..-■.'

. Millar, P.S.A., an undoubtedly able though somewhat expensive engineer, characteristically gave the following as his opinion:— >: i-.v-. ■.■■:■ ■.'..■■ . ■-■' : "It may not be considered,out of place to animadvert upon the engineering sewerage errors of the ,-past and '.present, ages.. The ancients,'in the selection of a locality, for the outfall for the sewerage of Imperial Rome— the • Cloaca Maxima '—caused' it to .. discharge into1 the Tiber ; iv consequence of which engineering error this magnificent work has • become totally useless,: although, having an emissaiium .14: feet wide byi.32 feet high^-fiom the fact that the;bed of. the river ' has . become elevated by the accumulated sewage of centuries j »whereas, if it had its termination on the shores of' • the Mediterranean , Sea, >as it might, it would have kept open to this day, and.for all time. Precisely similar.. re«, marks are applicable to the modern arterial jsewage circulation. throughout Paris/ in which, although a "model work; of its kind, the same, engineering error has been com: mifcfced, in having its outfall into the Seine, .causing- a further shoaling of that already shallow river, besides creating an ebb and flow of foetid waters upon a large scale. The modern engineering error of 1862-3-4, which I more; particularly allude to,.is the location, of the outlet for the 'Great London Sewerage,' which- will; discharge itself into the; Thames at such a distance from London as is supposed will prevent its return by the flood, tide—a supposition I without ; hesitation characterise as an engineering fallacy, quite as great, as was commit bed in Rome 2000 years before—-whereas, if it had been carried to the shores of the German Ocean, it would keep clear for ages. .Such a|-fate. as. has befallen Roman sewerage ,1 for'the Lbndonone, and awaits that of the City of Duriedin,.,if by any misdirected counsel the sewe^ be discharged; into the.karbour'permanently, instead of the. sea at .the O;ean Beach.";;. . ■•-■ -:':; ■ .-■ ..-. '■■■.. ■■' -: ■'■■■.-.' \ .'.■

0. R. Swyer, Trovincial Engineer, gave it "as his opinion that— ;. .• :.... - : .. . ; ' "The third condition is ope of the greatest importance in.a sanitary point of view. In, towns which discharge the contents of their sewers into tidal rivers or harbours,- the in ■", habited low portion of the .town; is liable to' injuiy from the. refuse being pent up in the sewers daring high, water,..and more, especially from the accumulation, of filth at the outlets, and along the high-water mark. If sewers must .discharge into the streams, rivers,/.or harbours, the, outlets should be at such a distance below the town as would render, the. refuse iinnoxious— that, is, > the outlet from the sewers should be placed at. such a point that the contents of the .would certainly be carried; -beyond injurious tidal, Lnflueuce; . or, , in' other words, .that there would be no probability of refuse once discharged into:the-river:,or harbour, being re-delivered into the,sewerß at, tho ;return,of thetide^ :.'./....'%;' : ,.'w /• '.■■'..':'.=' ■. ~:; ; -,

|"The positjon of Dunedin,with respp'ct^to,. its Jbarbouf and th? tidal influence r -is one. which will-.require the most-.careful', con?. siderationr-. with, respect tjo, this : view of the question.., Thedistance from^oneextremity | of Otago Harbour, to the,other is,about 13 j miles, and the... flow,, of the tide,, as taken.! from Admiralty charts, is, on an average,.one;and a-half mile per hour; therefore,any refuse di6c,harged;' into the Harbour -at Danedinathign w.a,ter-wouidi tinder javour\able circumstances, /have travelled nine, miles before;the turn of the tide,-or four miles less than would be required, to discharge it.into, the. Ocean. : , The.consequence would be. that all the solid:portions pfthersewage would be depoaitad on the numerous banks ■within the: harbour, or along- the jtiigli- water mark, the sowage in solution;;being; retained in,.,the waters of • the harbour, which, ;in -.{the, course of time, would be reduced to a gigantici cesspool, and would; become fouler, and fouler every year." ~..,.,.,., ~.,,.... ...... r ■ James ;M. Balfour, marine engineer, in his, ;rep'ort f stafed'.:-^- >;"; "\ *'""'Y:". .:"''''.'-'.' ::'"~ ] \ "I conaider it'only rigbt;to;express 'my1 conviction .that ;the Ocean. Breach' is'ijbbe: proper place for'the .drainage outfall, for at least a very large^portion.pf: the Cityof Diinedin;:'"; "■■', ' !i;:.'p ':' !'''.'' i!.\;; l '■'."',■*:'-''■; !'"('

■ ";At [a distanceJfrom the city, and'Bufficiently removed' from all'^habitations;r an outfall, .could; be' constructed therej dis- - charging:' directly' 'into n :the'. K' ever-resil^as' ocean, .which,; -by; its .constant' agitaticn, would effectually: prevent .any acbumulaitibii of deleterious matter; while, on'the other hand, when the utilisation of sewage cornea to be better understood, and capable of-being: carried "out-with, economic success,/there,is ample space on the beach itaelf for the coirstruction of all necessary,works... : i- . ...- . :

. ■ "That the removal of the sewage outfall to a distance from Danedin /would be; most beneficial tc its, sanatory condition must.be self-obvious. iOne has only to approach the shores of the Bay, or^toetand en any of the jetties at low water, even now, to be satistied that even the. present .very ; moderate discharge, of sewageVinto the., harbour is fraught •with,, Berious evils to the community. ",'' "■';. •'■"•'•.'•l'!;. ''■''■". ' ;:': '^ .'■■'■'• /' ■ " the whole'sewage of 'the city at' once hurried ; into the Bay by a complete system'of drains, the effect would certainly be to render the tidal, beaches: pestilential in' the extreme— dangerous .enough to,;those only who hud occasion at times to approach them,, but fraught with deadly, poison, to those who vere constrained to dwell in tlieir vicimty v .': ...^';;:.'"./'.' '/,., ' '..""';'.' j "1 assume then, da. of course;', that if .the. sewage Gf Dunedm is to be discharged into the Bay, certain works must be undertaken to protect the city from, its injurious effects j j anci It becomes .a question whether- these works could be more economically carried out thail the' construction of a great outfall sewer. The works in the Bay would have;, however, collateral advantages,' as. shall:be afterwards pointed out.'' Should,''however, it be decided, for the present at least-, not to" carry the sewage to the ocean, it will probably be only a temporary delay, and I should kt consequence recommend that the possibility of future extension-be kept in view, and the main drains of the city laid put >n such a manner as to admit of their being afterwards,'. at a "comparatively moderate expanse, intercepted ■■by - a great' sewer,' the line and levels of which h»d been carer fully studied and arranged from th 6 first." It is well to bear in mind that these opinions were written more than 12 years since, when the population of the city and suburbs was very much smaller than it is now, and that consequently the evila then were less to be apprehended than at the pre. Bent time. ■ ;

In the face of puch evidence the Harbour

Board feels compelled to offer the most strenuous opposition to any proposals under which there would be a risk of incurring evils of which the community has been so plainly warned, and it considers it it 3 duty not to give countenance to schemes of a mere temporary character. The Board would remind the Corporation that authority was given by the. General Assembly, in 1875, to its borrowing £100,000 for the special purpose of the drainage of the city, and it believes it is correct in saying that the estimated heavy cost of carrying an intercepting sewer to the Ocean Beach was one of the reasons urged for requiring such a large sum. The ieason\for constructing the branches before the^main:. trunk can of course only be gnes'sed at, bufc the Board is of opinion that it would be un-' safe for it to be a consenting party, uuleas under a formal agreement, to any temporary discharge into the harbour.' The Board is also of opinion, from a pecuniary^ point of view, that permitting a discharge into' the harbour %vould be a mistake. On this point the Board would call the special attention of the Corporation to the report of the Board's engineer, aud also of the Inspector of Works,1 premising that prior to the last flood, and within two yeara, the removing the deposits from the mouth of Kattray street sewer has cost the, Board at least .£7OO, besides. an almost continuous loss of berthage room for vessels. The Engineer, on the sfch inst., in his monthly report; thus: wrote:— " The discharge of solid matter into the steamers' basin from the Rattray street sewer: is becoming so constant and excessive in quantity that, unless remedial measures are adopted at an early date, the berthaga space at the upper extremity of the": basin and along the cross wharf wilLbe ren-: dered unavailable. I trust that the Board will take tho subject into early considera-; tioD, in order that the Corporation may>be. induced to remove the. point:of discharge to a part in the foroshore near the lower end: oik High street, or some other jprb where the harbour will not be injured thereby." On the same date the lnspecter of Worka' reported— ' • Regarding the Ratti ay street sewer, I beg to remark that if tliß debris which" iis discharges be allowed 'to accumulate it will soonfill up the steamers', basin go as to render, it practically useless for the purposefor which it was dredged." ■ ; ;The attention of the Board having been; directed to an undoubted grievance, it wbnld" respectfully warn the Corporation that the Board's dredging plant having been handed over- to Mr D. Proudf oot, contractor, in accordance with his contract, at present it! : has .id means of/removing the accumulation' of deposit's, the extent, ahd.'seriousneEs of. which may, be arrived at by.a perusal 'of the* following memo. ,bf the Board's Engineer. The Board may further1 mention that liad it -not beeathajb the mouth of the. sew>rJhad, just been cleared ;_away before the.lasib flood, in all probability if would have, been cdm-; pletely choked up, and v the most serious damage to both public and private property . would have resulted. v Altogether,' the fiub-" ject is one of so urgent' anil' important a character that the Board desires to express the hope that the Corporation will promptly and earnestly take it into its consideration^' and before any damage may result/tak^ the necessary steps to divert the Eattray street channel from itsi presentcourse. .. ' •"' -' ;V Meino. as to depositsfrom the Eattray-' street sewer into the steamers'' basin :— Quantity,of, solid, material discharged during, the last flood, 40^0 cubic yards; average quantity deposited in; ordinary floods,. 21500'; cubit yards ; average / quantity deposited.1 daily, irrespective of floods or "rain, 30 cubic yards. .. ' J';:'..' ~""" '-"'■■ .; " ■' ' '■"■'[ ':''

■ '"The above quantities are: approximate/ but they may be practically "accepted ai re-' liable.'. Witnsuch deposits as the foregoing1 it Trill be evident that a; considerable .berth-' age'space will be monopplised, yi-ithbut taking.into; consideration the expense of the removal oE' the material j'and if th^: workvof dredging at the mouth; of the sewer ,is not incessantly carried .on "by. the side dredge, the entire channel aiiljoining th 6 Rattray. street Wharf will a * no distant' date be reW dered unfit for the accommodation! of the5 class of sieamers'and visa'eis- that now fre-; quent t)unedip. ~~' - ■ :" As to the sewage generally that is discharged into the bay, niy views are. succinctly expressed upon the subject in my general report upon the harbour, to which I would refer. ; '

"i>. L. Simpson,^.Engineer."