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Difference from
Mr. Cooper's scheme.
Float experi- ments of Mr, thai wick and
It will readily be seen, that I differ very essentially from Mr. CoorR'S Scheme, in providing outfalls for sewage into the harbour at a number of points, instead of at the four points C. 1, C. 2.. O. 3 and C. 4 marked on Plate 1.
An experience of ten years in the Colony, and having had an office for six years on the Praya front, opposite Peddar's Wharf, and having always carefully observed the course of the numerous cargo boats and traffic by the side of the Praya, convinces me, that there is an almost equal strong current at any point along the Praya from Wellington Battery to Belchers Point, and that there is very little difference in the speed of matter, either Eastward or Westward.
The float experiments of Mr. CHADWICK and Mr. COOPER were confined to particular points, and in no way cause me to alter the above opinion. Therefore it would be far better to discharge smaller portions of sewage at a number of Mr. Cooper. points, and thus diffuse the matter more thoroughly, than greater portions of
sewage discharged at three or four points only.
Strong tide-
Chinese
It would need but a very slight acquaintance with the Praya to see, that way opposite where the large population of Chinese are, the Praya Wall has been constructed quarter. in the deepest water, and consequently in strong tideway, which would effectually carry away any matters discharged by properly constructed and numerous outfalls. At a very little distance from the Praya Wall, (as will be seen from the length of the wharves), ocean steamers are berthed.
Lesser tide- way at
There are places, such as opposite the City Hall, Commissariat Pier and certain places Bowrington, where the configuration of the Praya would naturally lead one to not affecting expect slack water; even at such places, I consider, that by suitable length of outfall, there is amply sufficient current to diffuse the small amount of sewage discharged at those places.
outfalls.
Objection to outfall at Bowrington Canal.
Advantage of
numerous
direct
outfalls.
No feest
At Bowrington Canal especially, there exists a large foreshore caused by the deposit of silt washed down the Wong-nei-cheong Valley. The outfall, proposed by Mr. COOPER at C. 4, is essentially wrongly placed for a collecting sewer, as admitted in the report by the recommendation to carry this discharge by pumping to North Point.
An advantage in having numerous direct outfalls is, that sewage would be more rapidly discharged into the sea from its place of production. I estimate that from no part of the City would the sewage take longer than two hours to be dispersed into the sea. Sir ROBERT RAWLINSON in his "Suggestions," says: All sewage should be disposed of, if practicable, on the day of its production." This would not be the case with low lying intercepting sewers; and in a tropical climate, it is essential to have the most speedy discharge.
An important fact which must not be forgotten in considering the matter exist. discharge into the harbour of the sewage of this City, is, that practically no focal matter exists. The disposal of night-soil being carried out by the bucket system.
Disapproval of increased
I disapprove of any increase in the number of water-closets, which should number of only be allowed in the Hotels, Clubs, or large Public Institutions. There is not Water Closetstherefore the liability of having floating matter brought down by the sewers into
the harbour.
Proposed new reclam.stion
I have made no mention of the proposed reclamation from the Harbour in advantageous front of the City and shewn on Plate No. 1, as it is obvious that the sea wall to outfalls. would project into deeper water, and greater tidal currents, thereby diffusing the discharge of outfalls still more rapidly. The work of constructing such outfalls would be a simple matter in building the new wall, which will be in from 15 to 40 feet depth of water.
Intercepting Sewers
The employment of four outfall points only, necessitates the construction. necessary to of intercepting sewers, low-lying and of very flat gradients, such as 1 in 1,000 to Mr. Cooper's 1 in 1,700.
Scheme.
Construction costly,
Intercepting Sewers
The construction of these sewers would be extremely costly, the soil is made ground, practically sand free to the sea, the trenches would be continually flooded and heavy pumping would be required; in many places, without close piling, no pumping would contend with the sea.
Besides, granted that the sewers were constructed, they would be backwatored."backwatered" every high tide. During the South West Monsoon (especially
when typhoons are in the neighbourhood) the sea level remains abnormally high for lays together, there being no rise and fall of the tide, and during such times the sewers may be called upon to work under pressure.
It must also be remembered, that these intercepting sewers by not having suting of
intercepting a free outfall, can never be emptied; silting, in this case, must take place, interce necessitating, either very heavy flushing, or periodical cleaning out of the silt pits.
Gas from
A source of danger is also created by the sewer becoming an elongated Discharge of tank with slow velocity, constantly giving off sewage gas, which must be discharged intercepting somewhere, and no doubt the tendency is for it to be distributed up the tributary Sewer,"
sewers,
of Brighton
I would here like to give the experience at Brighton of the low level Experience intercepting sewer. In a paper read before the Institution of Civil Engineers, intercepting the Borough Surveyor of Brighton gives as his opinion, that, for a town like Sewer. Brighton, the system of pipe outfalls into deep water was a good one, and that, from a sanitary point of view, they were not better off, after having built the seven miles of intercepting sewer, than they had been with the outfall pipes previously laid.
The outfall pipes mentioned were taken to a lowest depth of 8 to 16 feet and discharged into the sea.
Mr. Monson on inter-
Sewers.
In the same discussion, Mr. MONSON made observations applying to large Opinion of intercepting outfall sewers generally; he objected strongly to the large quantity of sewage gas that was being constantly driven off, and that the sewage was blocked cepting in by the tide and consequently sludge was freely deposited, the ventilators that' were put in could be of small area compared with the volume of sewage, and he believed, that the resident medical men considered the scheme the reverse of satisfactory.
The intercepting sewers, running along the Praya East and West, will have Low level of intercepting to cross at right angles all the numerous Praya outfalls, which are at various Mr. Cooper's levels. The sewers cannot go over or through them, and going under will Sewers. necessitate a considerable depth at the beginning. The only alternative is to With sewers at such resort to syphons, of which only two or three are proposed. flat gradients, on either side of the syphon, very considerable difficulty will be experienced from deposit.
In recommending the adoption of the Combined System for the purely Combined Chinese part of the city, I am, besides following the recommendation of for Mr. CHADWICK to use such of the sewers as are suitable for the conveyance of districts sewage, utilizing the large amount of new drains, constructed by the Government subsequent to the date of Mr. CHADWICK'S report.
Chinese
utilizes
existing Sewers.
In a speech delivered by the Surveyor General at the Meeting of the Remarks of Legislative Council held on the 5th November, 1886, the following words occur:-
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the Surveyor General on New Sewers constructed.
With regard to the words that have fallen from the hon: member opposite with reference to Sanitary Works, the hon: member may be aware, or he may not be aware, that the Government of the Colony has been for the last three and a half years assiduously engaged in reconstructing the main sewers of this town upon modern sanitary principles. From the returns which I hold in my hand I find that during the last three and a half years in the Western District of Victoria 2,450 yards of main sewers have been constructed, in the Central District 1,900 yards, and in the Eastern District 3,100 yards, making in all 7,450 yards of new main sewers, or, roughly speaking, about four and a half miles. Besides this, many other works of improvement in connection with main sewerage have also been carried out, and these improvements have been pushed forward for the last three and a half years and are still being unremittingly pushed forward from day to day as part and parcel of the comprehensive scheme for the main drainage of the city adopted four years ago. The main drainage works of Victoria, however, are something like Rome, they are not to be built in a day. At all events, the statistics I have quoted to the "Council will show that considerable progress has been made in the main drainage works. Having said this much on the subject of the main drainage of the town, I come to the cognate subject of house drainage, and here I am able to agree with any hon: member at this table who may lift his voice against the actual condition of things. House drains are to the main sewers what the veins are to the arteries in a man's body. The Government have been engaged in restoring the arteries to proper working order, and it devolves upon the
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