572
Jervois St.
and Bonhama
described.
10
I would mention, as an instance, the drains in Jervois Street and Bonym Strand drains Strand. Instead of conveying the drainage of the district by the most direct way into the harbour, the sewers run nearly parallel with the Praya, discharging at Possession Point. As this district is low lying, the sewers are nearly level, and cause great trouble from silting up. I have mentioned, that I consider exactly similar trouble will be experienced with Mr. COOPER'S proposed intercepting sewers of flat gradients.
Mr. Chad- wick's
description
of Bonham
Mr. CHADWICK mentions the sewers in this district in the following terms :-- Much inconvenience and expense is caused by the necessity for cleaning Strand drains. out periodically the portions of the sewers where they cross the low districts
"about Bonham Strand."
Inability to
objection.
I fail to see why, even granted that there be considerable deposits during see cause of the dry season in the large sized sewers of the lower levels, that this is a reason for not using the bulk of the sewers, already constructed, for the conveyance of sewage,
Objection (3.) No ventila-
tion no
Feason for
not using
existing
Sewers.
Mr. Chad.
wick on absence of
With reference to objection 3. Mr. COOPER alleges, as a reason for not using the existing sewers, that no efficient means of "ventilation exists.” This is obviously no reason for not so altering the present sewers, as the cost of making ventilators cannot be so expensive as the construction of new sewers and ventilators.
The statement, that no efficient means of ventilation exists, is supported by Mr. CHADWICK in the following words, which naturally apply to the date of his ventilation. report.
Ventilation main
by shafts.
"There are no special ventilator openings either inlet or outlet, nor does "the necessity for ventilation appear to have been recognized. The drains, which receive the water from the ravines above the town, have open outlets at their upper ends or intakes, and so they are to some extent ventilated. Where the drains do not run up the hill sides there is no proper ventilation. For instance, "the drain along Old Bailey Street terminating in the Caine Road. In one instance, that in Peel Street, the natural ventilation of the sewer has been prevented purposely by the construction of a trap at the top, thus the uprising sewer gas has no means of escape except by untrapped house drains and gully holes."
The only attempt at ventilation, made up to the present date, are the few Sewers only shafts built within the last year at the upper ends of the main drains, and it requires no argument to show, that these only ventilate a very little distance, and the open ends of the drains as before, were practically equally efficient, the only advantage gained by the shafts being the very small difference in the density of the gases for the additional height. These shafts, as I stated in my evidence before the Fever Commission, cannot ventilate any of the side junctions to the main drains, as the gases would then be called upon to descend the side branches. and ascend the main drains.
Sir Robert Rawlinson of ventilation.
Sir Robert
necessity for Hlap valves.
The opinions of Sir ROBERT RAWLINSON is, that:---
"Sewers formed along steep gradients therefore require to have more care "bestowed on the means of ventilation than other sewers laid along flat districts "to prevent the dangerous accumulation of sewage gases in the districts. Ordinary main sewer ventilation should be provided in all cases at intervals not
upper greater than 100 yards.”
+6
The ends of sewers and drains at their lowest outlets must be so protected Rawlinson on that the wind cannot blow in and force any sewage gases back to the streets and houses. Flap valves or other contrivances may be provided to cover and protect outlet ends of sewers and drains and so prevent the wind from blowing in."
Flap valves a necessity,
Sir Robert
Rawlinson's
opinion that
numerous
ventilators are required,
and are no
nuisance.
<
This is a special requirement in the drainage of this city, as the upper levels are 400 feet above the Praya, and during the North-east Monsoon, when the drains are the foulest for want of rain water, the wind is blowing directly into the present open ends of all the outfall sewers:-
C
*
+
"It has been suggested that free and open sewer and drain ventilation will so taint the atmosphere within and over a town as to cause houses at a lower level to pollute those situated on the higher levels. Any serious injury from this need not be feared, as with abundant means of ventilation, the air. within the sewers, will be comparatively pure,"
11
www
Sewer and drain ventilation are insisted upon over and over again in these suggestions, because the work is so important and is so generally absent " or even wilfully neglected."
"There are many towns in which the sewers are not ventilated because the inhabitants refuse to have any open sewer ventilator at the street surface. This is a sad mistake, as a town, having unventilated sewers and house drains "connected with them also unventilated, must have disease in excess."
The above remarks of Sir ROBERT RAWLINSON, in his Suggestions for tipical drainage systems, prove the absolute necessity for ventilation of sewers.
evidence on present
I was surprised to read the evidence of Mr. CooPER before the Fever Mr. Cooper's Commission. that he considered serious harm would arise from openings in the streets in the present condition of the house drains, as it is obvious from the construction opinion of Sir ROBERT RAWLINSON that the sewers have to be ventilated at some time, and no amount of defective house connection cau justify the absence of such ventilators, which any way must improve the air in the sewers.
of ventilu. turs.
I do not agree with the statement of Mr. CoorFER, that the gases would be Disagree. drawn into the houses by reason of the air being warmer, as the temperature: of the interior of the houses is usually lower than that of the open street, for the views. greater portion of the
year.
proposed With reference to the proposed works of Mr. COOPER, the words of his Mr. Cooper's report are:-
inent with
the above
works.
Ei
44
"After careful consideration of the whole of the foregoing facts and a close study of the locality, I am of opinion that the ends of efficiency and economy will be best met by :---
1.The construction of a new system of pipe sewers admitting only
Li
x
a limited quantity of surface water and by adopting outfalls for such a system at suitable points East and West of the City.
2. The utilization of the existing drains for conveying the natural "streams through the City and for carrying off surface and subsoil water."
The proposed works are, therefore, the carrying out of what is known as Proposed the "Separate System."
works are ou the
Separato Systom.
commended.
Wherever the Separate System is capable of being conveniently carried separate out, it is unquestionable the more sanitary system, and I strongly recommend its stender adoption for the Yellow areas, but I maintain, and hope to prove, that the Separate System is totally unsuited, not to say impossible, over the Red area.
Mr. Cooper's
Mr. COOPER mentions, as an objection to the use of the same sewers for Disagree sewage and subsoil, that in case of stoppage of foul water the sewage may back men with into the subsoil drains, and sewage gas escape through them into the houses. I objection. entirely disagree with this opinion as a reason for not adopting the present sewers on the Combined System for the Chinese districts. The only places, where subsoil drains are required, are in the higher districts, which I propose to deal with under the Separate System; besides, efficient ventilation to the sewers would obviate any such nuisance.
houses.
The entire area coloured Red is built over in a manner quite unknown at Description home. The width of a Chinese house is 15 feet from centre to centre of the side of Chinese walls, leaving about 13'-6" in the clear; they are either built back to back, or have a yard or lane of about 6 feet wide. By the New Building Ordinance, this width is slightly increased for lots acquired from the Government after the passing of the Ordinance, but that cannot therefore affect the present City.
by the
The back yards are used for washing and domestic operations, and are the Ulitization receptacles of the refuse of the houses. There is usually to be found the latrine chinese of of the house, and in days not long past, the well.
"C
Mr. CHADWICK's description is as follows:-
As the upstair lodgers have no convenience of getting rid of their rubbish, much is stuffed down into the down pipes, choking it. causing it to "leak and saturate the walls with the filthy fluid. "For the same reason also the
house drain is frequently obstructed."
The back yard measuring 13'-6" by 6'-0" is little better than a sink, and, compared with the average number of inhabitants, would not contain more area per head than an English kitchen sink.
thy back
yards.
No comments yet.
Private notes are available after approval.