CO882-(3-4) — Page 499

PUBLIC RECORD OFFICE

Reference:

TTC.O. 882

ALLY WITHOUT PERMISSION OF THE BE REPRODUCED PHOTOGRAPHIC-

COPYRIGHT PHOTOGRAPH-NOT TO

PUBLIC RECORD OFFICE, LONDON

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either vertical or horizontal. He shall cause every branch drain or tributary drain to join another drain obliquely in the direction of the flow of such drain.

65. Every person who shall erect a new building shall, for the purpose of securing efficient ventilation of the drains of such building, comply with the following require-

ments :-

(I.) He shall provide at least two untrapped openings to the drains, and, in the pro- vision of such openings, he shall adopt such of the two arrangements herein- after specified as the circumstances of the case may render the more suitable and effectual.

(a.) One opening, being at or near the level of the surface of the ground adjoining such opening, shall communicate with the drains by means of a suitable pipe, shaft, or disconnecting chamber, and shall be situated as near as may be practicable to the trap which, in pursuance of the byelaw in that behalf, shall be provided between the main drain or other drain of the building, and the sewer or other means of Such drainage with which such drain may lawfully communicate. opening shall also in every case be situated on that side of the trap which is the nearer to the building.

The second opening shall be obtained by carrying up from a point in the drains, as far distant 28 may be practicable from the point at which the first-mentioned opening shall be situated, a pipe or shaft, verti- cally, to such a height and in such a manner as effectually to prevent any escape of foul air from such pipe or shaft into any building in the vicinity thereof, and in no case to a less height than "10 feet."

(b.) In every case where the foregoing arrangement of the openings to the drains be impracticable, there shall be substituted the arrange-

may ment herein-after prescribed.

One opening shall be obtained by carrying up from a point, as near as may be practicable to the trap, which, in pursuance of the byelaw in that behalf, shall be provided between the main drain or other drain of the building and the sewer or other means of drainage with which such drain may lawfully communicate, a pipe or shaft, vertically, to such a height and in such a manner as effectually to prevent any escape of foul air from such pipe or shaft into any building in the vicinity Such opening thereof, and in no case to a less height than 10 feet. shall also in every case be situated on that side of the trap which is nearer to the building.

The second opening, being at a point in the drains as far distant as may be practicable from the point at which such last-mentioned pipe or shaft shall be carried up, shall be at or near the level of the surface of the ground adjoining such opening, and shall communicate with the drains by means of a suitable pipe or shaft.

(II.) He shall cause every opening provided in accordance with either of the arrange- ments herein-before specified to be furnished with a suitable grating or other suitable cover for the purpose of preventing any obstruction in or injury to any pipe or drain by the introduction of any substance through any such opening. He shall, in every case, cause such grating or cover to be so constructed and fitted as to secure the free passage of air through such grating or cover by means of a sufficient number of apertures, of which the aggregate extent shall be not less than the sectional arca of the pipe or drain to which such grating or cover may be fitted.

(III.). Every pipe or shaft which may be used in connexion with either of the arrange- ments herein-before specified shall be of a sectional area, not less than that of the drain with which such pipe or shaft may communicate, and not less in any case than the sectional area of a pipe of the diameter of 4 inches. (IV.) No bend or angle shall (except where unavoidable) be formed in any pipe or

shaft used in connexion with either of the arrangements berein-before specified. (V.) Provided always, that for the purpose of either of the arrangements herein-before specified the soil pipe of any water-closet, in every case where the situation, sectional area, height, and mode of construction of such soil pipe, shall be in accordance with the requirements applicable to the pipe or shaft to be carried up from the drains, may be deemed to provide the necessary opening for ventilation which would otherwise be obtained by means of such last-mentioned pipe or shaft.

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66. A person who shall erect a new building shall not construct any drain of such building in such a manner as to allow any inlet to such drain (except such inlet as may be necessary from the apparatus of any water-closet) to be made within such building. He shall cause the soil pipe from every water-closet in such building to be at least "4 inches" in diameter, and to be fixed outside such building, and to be continued upwards without diminution of its diameter, and (except where unavoidable) without any bend or angle being formed in such soil pipe to such a height and in such a position as to afford, by means of the open end of such soil pipe, a safe outlet for sewer air.

He shall so construct such soil pipe that there shall not be any trap between such soil pipe and the drains, or any trap (other than such as may necessarily form part of the apparatus of any water-closet) in any part of such soil pipe.

He shall also cause the waste pipe from every bath, sink (not being a slop sink con structed or adapted to be used for receiving any solid or liquid filth), or lavatory, the overflow pipe from any cistern and from every safe under any bath or water-closet, and every pipe in such building for carrying off waste water to be taken through an external wall of such building, and to discharge in the open air over a channel leading to a trapped gully grating at least 18 inches distant.

He shall, as regards the mode of construction of the waste pipe from any slop sink con- structed or adapted to be used for receiving within such building any solid or liquid filth, comply in all respects with such of the provisions of this byelaw as are applicable to the soil pipe from a water-closet.

filment of

1. The above extract from the "Model Byelaws" promulgated by the Local Govern System of ment Board gives, in general terms, the points to be observed in order to secure effective house con- house drainage. It will be seen that the system of house construction which obtains struction in Hong Kong in Hong Kong renders it impossible, in the case of many existing buildings, to satisfy in the case all the prescribed conditions. For example, in back-to-back houses the drain must pass of old houses under the house (byelaws, para. 62), and the drain must have an inlet within the house prevents ful- (byelaws, para. 66). It is possible, however, to follow the general spirit of the precepts, requirements and to make such arrangements as will reduce to a minimum the chance of evil results laid down in

byelaws. from these deviations from strictly correct practice.

2. In the case of a great majority of dwellings, the poorer class, it is obvious that the Economy cost of the works must be reduced to the minimum amount consistent with efficiency. second only to efficiency Hence, the simplest and cheapest means to secure the desired end must be employed. In some cases facility for inspection and repair must, to some extent, at least, be sacrificed to economy in construction.

in import-

ance.

Good design

Becare

3. Nevertheless, in the vast majority of cases, good design and good workmanship and work- will secure all the essential requirements of good drainage. True and accurate work manship greatly reduces the chances of stoppages, and diminishes, indeed obviates, the necessity alone will for the more elaborate provision for their removal, whilst good design derives the efficiency. maximum efficiency from simple means.

They can With bad workmanship, however elaborate be the system adopted, failure is certain. only be This is a most forcible argument for the execution of such work by Government, who attained by

execution of alone can secure the services of an efficient staff for this purpose. Other equally cogent work by reasons will be given later.

Government. 4. In addition to the general conditions prescribed in model byelaws referred to, there Technical are certain technical requirements, the necessity for which has been demonstrated by points to be experience, and to which attention must be paid to secure good results.

attended to in addition

5. The discharge of sewage from any individual house is both intermittent and highly to general irregular in amount, depending in a great measure on the habits and occupations of the require- inmates, as the volume to be carried off is an unknown quantity; hydraulic formula ments. afford no assistance in determining the necessary dimensions and slope of the pipe. It Gradient on has been found that a 4-inch pipe with a fall of 1 in 30 will, under ordinary circumstances, fall required serve every purpose and keep free from deposit and obstructions. This size, therefore, for house has been adopted as the standard house drains, and a fall of 1 in 30 is also the minimum, street sewers. and as much more fall should be given as is practicable.

It must be remembered that a pipe of this size with this fall is capable of carrying off vastly more than the sewage of any one dwelling. The use of sinaller diameters has been found to be undesirable on account of their liability to obstruction by solid substances casually introduced, and because of the resistance to the circulation of air in ventilation which they offer, and above all because of the difficulty of obtaining small pipes true and straight.

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drains and