DRAINAGE OF WELLINGTON.

Globe, Volume VII, Issue 746, 9 November 1876, Page 3

DRAINAGE OF WELLINGTON.

[Prom the JBoening Post."] The Philosophical Society's meeting on Saturday evening proved the moßt important and interesting yet held by that body. It has been proposed in the City Council to request of the General Government permission for the principal engineers in the colonial service to advise the Corporation as to the system of drainage most suitable for Wellington. The question admittedly is one literally " of life and death" to the inhabitants of this city, and iti free discussion by some of the leading engineers, doctors and savants of New Zealand, as on Saturday night, is of peculiar local interest, We regret that our space will not permit us to give the full and detailed report which alone could do justice to this momentous subject, ani that we can only indicate the Hue of argument pursued by those who spoke on the occasion. The main feature of note is that some of the leading engineers in the Government employ gave freely the very opinion it was proposed to seek of them by amove roundabout process. The Oolonial Engineerin Chief, Mr Carruthers ; the superintending engineer, Mr Higginson ; Messrs O'Neill, C.E, Maxwell, C.E, and Campbell, C.E, represented the engineering view of the matter, Drs Newman and Hector may be supposed to have represented the medical, Dr Bailer and Mr Travers, the general scientific, and Messrs W. B. E. Brown (Registrar-General) and J. H. Wallace (the author of the Corporation prize essay on the subject) the practical point of view, while the lateness of the hour alone prevented expression of opinion from many others present who might have spoken with undoubted authority on various aspects of the question. The discussion arose on Mr Campbell's paper " On Drainage of Towns." The author explained the diffe. Mat ystems in use, and gave some curious

calculations aa to the saving of life resulting from the establishment of efficient drainage, the local application being to the effect that whereas the annual death-rate per 1000 from zymotic (or in other words, preventible) diseases in 68 of the largest English townn was only 3 6, and in the country districts 2 9 in the seven largest New Zealand towns it was as high as 8 63, and in the country districts 3'17. Thus, if the Wellington deathrate were only the same as the English town average, 32 lives would be saved every year, while if the excess of deaths in town over those in the country were only the same as in England, no fewer than 100 lives would be saved in Wellington annually. Mr Campbell apparently was in favor of either a dryearth or " pail" system (as in use at Manchester, Salford, Halifax, Woolwich, &c), or, if water carriage be used, of the "separate" system, in which a double set of sewerage is employed, one pipe carrying off the rainfall and road washings, the other taking the house and yard drainage. The latter sewer is laid at the backs of the houses in order to avoid laying the house-connection under the dwellings from back to front, any leakage from which would render the house unhealthy. This system was recommended by the General Board of Health in England, and it is contended that its great advantage is that pipes could be used to far greater extent and the sewers could be smaller, than in the "combined" system, by which one sewer is made to carry off the whole drainage. It was also urged that the drain pipes from each house should discharge upon a grating leading to a sewer and not be connected with the latter, so aB to avoid the ascent of sewer gases into the house. Commenting upon this last point, Mr Higginson mentioned that this danger is incurred in the highest degree by the pievalent practice of having a waste pipe leading from the cistern to the water closet, from which the noxious gases arose through the pipe and poisoned the water. Mr Carruthers made a most interesting and —under the special circumstances—important speech. He condemned the dry earth, pail, and separate systems, and advocated the use of single egg-shaped sewers of large size to carry off the whole drainage Mr Carruthers went into statistics showing that on investigation and analysis, it was found that the sewage resulting from road washings contained almost, if not quite, as much matter dangerous to health as that from house, yard, or closet. He maintained that the street sewers would require to be quite as large in the separate as in the combined system, thus increasing the cost of construction. The dry earth system required a far greater supply of earth than was generally supposed, thus the cost of cartage would be very great, while the profits expected to result from the sale of manure proved almost wholly illusory.,Mr Carruthers contended that " sewage should be regarded not as a friend to be made use of, but as an enemy to be got rid of," He advocated discharging it into the harbor, and expressed the opinion that—provided the currents were duly studied, and the outfall properly placed —no ill effects would be experienced, at any rate, for 10,000 years or so. Mr Higginson took much the same view of the general question. Mr Blackett, the assistant engineerin- chief, declined to offer any remarks on that occasion. The other speakers held a variety of views. Some were strongly in favor of utilising the sewage as manure, and returning it to the soil, Dr Newman and Mr Campbell urging that deodorisation by ashes, the pail system, worked well, and gave some return towards the expenses. Several spoke forcibly against the pollution of the harbor, and adduced the experience of other places to show that the effects of such a plan were most disastrous. It was contended by some that the currents in the bay were quite iusufficient to exercise any scouring property, and that the sewage, even if carried out a little distance by one tide, would be brought back again by subsequent tides. The Regis-trar-General mentioned an instance of a bathing-dress being washed away and brought back again by the tide many days afterwards. The whole discussion went to show in how ;many difficulties, doubts, and differences of opinion the subject is involved, and how exceedingly important it is that before any scheme is undertaken, the entire question should receive the fullest and most thorough investigation. It is estimated a complete sjstem of sewerage for this city would cost at least £150,000, representing a tax of not less than £7500 per annum for interest alone, and it is of the utmost importance that this heavy outlay should be carefully and wisely directed.