(ix)
(heading) in petition) from the storage of garbage and refuse material in the native town just below Bonham Road, and from the burning of refuse matter in an imperfect manner at Láp-sáp-wán; in a fifth (heading Ein petition) from the noxious and fœtid gases concentrating in the upper levels from the absence of proper ventilation in the public sewer. It will be observed that these constitute the main cause of the petition being sent in, and during the cross-examination of witnesses they again constituted the main grievance.
In disposing of these grievances it is evident that the first four, (A, B, C and D of the petition), can be pronounced nuisances, but the fifth (heading E of petition), the absence of ventilators in the public sewers, is a technicality of sanitary engineering.
The Commissioners feel reluctance in going into the question of criticising the sewers of the Colony, whether as regards their shape, construction, intent as to what they are meant to convey or ventilation, because they are aware that by the recent Public Health Ordinance, radical changes will be made in the formation and flushing of the present sewers which, it is hoped, will improve, if not eradicate, many shortcomings which are at present only too evident. The changes recommended by the Government of the Colony have been agreed upon after deliberate consultation, and it is not the wish or duty of the Commissioners to criticise them.
The conditions of drainage met with in the Western District which struck the Com- missioners as calling for comment are :-
1st. The absence of ventilators.--As brought out in evidence there are no regular ventilators, that is, no openings constructed for the purposes of allowing the entrance of fresh and the exit of foul air, in the course of the public sewers. What openings there are, exist for the purposes of carrying off the surface water, with, in addition, a ventila- tion shaft at the top of the main sewers. The openings for carrying off surface water are in some instances trapped, in others provided with a metal valve and in a third set guarded simply by gratings. Of these it is plain that the first-the trapped openings- are not intended for the entrance or exit of air; that the second--the valved openings act imperfectly as ventilators, their very purpose being the complete closure to sewer gas, of the aperture they guard. It is only the third class therefore the openings pro- vided with gratings-which can serve the purpose of allowing free communication with the air, and it does not seem that they are adequate by themselves to provide for the 'oxidation of the sewer gases.
In addition to these openings many of the main sewers are provided with venti- lating shafts placed at different levels along the face of the hill. Some of these shafts are situated below, on a level with, or above the present house-building levels.
The shafts in question are intended to act as exits of foul air and the Commissioners found they fulfilled their functions to some, or it might be even to a considerable extent. That they serve to completely fulfil the purpose of ventilation of the sewers may be called in question; and the more so, as they are found only at the head of main sewers, whilst the branch sewers communicating therewith are left unprovided with such exits. In some instances charcoal trays have been placed in the ventilating shafts with the autho- rity of the sanitary board. They were placed there on the representation of residents that the exhalations from these shafts rendered their houses undesirable to live in. The Commissioners are of opinion that such charcoal trays, even when the charcoal is kept dry, greatly impede the exit of gas; but when the impossibility of keeping the charcoal dry in a moist climate such as that of Hongkong, even when the trays are roofed over, is taken into consideration, it is evident that they render practically useless such shafts. Further, that these ventilation shafts do not completely fulfil these functions, is believed from the fact that, from the surface water gratings, gases of a highly objectionable nature emanate; proving that the suction power of the ventilating shafts, is not of sufficient draft power, to not only check such emanations but does not cause the entrance of fresh air instead of the exit of foul.
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