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also the levels and sizes of any existing drains crossed by or adjacent to such new drains. Copies of Schedule A in English and Chinese may be obtained gratis on application at the office of the Building Authority, or, in the case of the villages, at any village police station between 10 a.m. and 4 p.m.:
Provided that when drainage works are being carried out in conjunction with other works it shall only be necessary to forward one form as set out in Schedule A, which must however contain particulars of the whole of the works including such drainage works.
Note. The approval of plans by the Building Authority under these regulations certifies simply to the fact that the plans are in accordance with the Buildings Ordinance, 1935, and with the re- gulations made thereunder, but signifies no approval of the sufficiency or otherwise of the plan and throws no responsibility on the Build- ing Authority.
4. Auy person carrying out excavations for drainage works on any premises contiguous to a public thoroughfare, whereby the safety of the public may be jeopardized, shall light such excavations by means of a lantern or lanterns kept lighted through the night, and he shall further provide watchmen, erect hoardings and otherwise take such precautions as may be necessary for securing the safety of the public and the protection of adjoining properties.
5. Covered drains and sewers shall be made of impervious materials, to be approved by the Building Authority, with smooth internal surfaces, such as well glazed earthenware pipes or cast-iron pipes protected against rust or corrosion by suitable asphaltic coat- ing, and shall be so constructed as to be water-tight and air-tight. In jointing pipes with cement, tarred hemp shall be caulked into the joints before the cement is applied, and care shall be taken that no cement or other jointing material projects from the joints into the interior of the pipes, and any such projecting material or other irregularities in the bore of the drain or sewer shall be carefully removed.
6. All drains and sewers shall be laid so as to have a firm bed throughout their length. Where the bottom of the trench is in rock or similar hard substance, the pipes shall be firmly bedded in suitable selected material free from large stones and well rammed into place. Where such drains or sewers are laid under a wall, they shall be protected by means of a relieving arch.
7. All stone-ware pipes shall be well glazed and free from cracks and flaws and shall have a thickness of not less than one-twelfth of their diameter.
8. That portion of the drain of any building which is immedi- ately connected with any sewer shall (unless specially exempted by the Building Authority) be provided with a suitable and efficient intercepting trap at a point situate on the ground of the owner of the drain as distant as may be practicable from such building aud as near BB may be practicable to the point at which such drain is connected with such sewer. Adequate means of access shall be provided to every drain by a manhole or disconnecting chamber or other means of access to be approved by the Building Authority for the purpose of cleansing the drain. All manhole and disconnecting chambers shall be constructed of brickwork at least nine inches in thickness built in cement mortar so as to be water tight up to the level of the adjacent ground and every drain or sewer connecting into such manhole or disconnecting chamber shall be continued along the floor of the chamber by means of open half- channel pipes set in a bed of cement concrete. The surface of the concrete shall be raised above the edges of the half-channel pipes and shall be floated with neat cement all over so as to present a smooth and impervious surface. Where tributary drains are nected to the main channel the manhole bottom shall be benched up in cement concrete at an angle of forty-five degrees and finished at the channel with a bull nose edge and such tributary drains shall be formed by means of curved half-channels similarly laid in the benching and made to discharge over the main channel.
con.
All manhole and disconnecting chambers shall be fitted with air tight covers and frames to be approved by the Building Authority.
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9. All covered drains and sewers shall be laid in straight lines and regular gradients between the points at which any change of direction occurs, and all changes of direction shall be made by means of properly curved pipes or by half channels in manholes.
10. Concrete for encasing drains or sewers shall be composed of four parts of good sound clean stone, broken to pass through & one inch ring, two parts of sand and one part of Portland cement thoroughly well mixed and well rainmed into place or of such other materials and in such proportions as the Building Authority may
approve.
11. Cement-mortar for the jointing of pipes or any other work shall be mixed in the proportions of not more than three parts of clean sharp sand to one part of good Portland cement and used fresh.
12. No covered drain or sewer shall be less than four inches in clear internal diameter, but the Building Authority may require any covered drain or sewer to be constructed of a larger diameter.
13. Subject to the limitation mentioned in regulation No. 12 of these regulations, no drain or sewer shall be larger than is neces- sary in the opinion of the Building Authority to carry off the sewage of the premises drained or the sewage with the rain-water, which, under conditions hereinafter specified in regulations Nos. 35, 36 and 37 of these regulations, shall be admitted to the drain.
14. Every draio or sewer shall have the maximum fall, throughout its length, that the relative levels of the public sewer and of the most remote inlet will admit of:
Provided always—
(a) that, if the available full exceeds 1 in 30, the part of the drain or sewer more remote from the public sewer may be laid with a fall of 1 in 30; and the remainder, with such greater fall as may be necessary to connect with the public sewer;
(b) that, if the excavation necessary to obtain the maximum available fall, is likely in the opinion of the Building Authority to endanger the stability of the adjoining or neighbouring property, the gradient may be modified to such extent as the Building Authority may approve.
15. Whenever the available fall for a covered drain or sewer is less than 1 in 30, the Building Authority may require the gradient of the drain or sewer to be varied by increasing such gradient in the upper portion of such drain or sewer and by reducing it in the re- maining portions.
16. Whenever the gradient of any portion of a covered drain or sewer is less than 1 in 30, the Building Authority may require an automatic flush tank or any other suitable contrivance for attaining an effective flush to be provided to his satisfaction.
17. No drain or sewer shall be so constructed as to pass under any domestic building except when any other mode of construction is impracticable. Any drain or sewer passing under a building shall be of cast-iron pipes coated inside with Dr. Angus Smith's patent composition, or of other material approved by the Building Authority, and all such pipes shall be of a quality to be approved by the Build. ing Authority and the joints shall be properly caulked and run with lead, and (unless the written permission of the Building Authority has first been obtained to lay the drain or sewer otherwise) shall be laid in one straight line for the whole distance beneath such build- ing, and shall be imbedded and encased throughout its entire length in four inches of concrete as specified in regulation No. 10 of these regulations.
18. Whenever a covered drain or sewer traverses soft or yield- ing ground, or when water may make its appearance in the trench. the drain or sewer shall be surrounded throughout its entire length with not less than four inches of concrete as specified in regulation No. 10 of these regulations.
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