THE HONGKONG GOVERNMENT GAZETTE, FEBRUARY 12, 1910.
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2. Any 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 pre- cautions as may be necessary for securing the safety of the public and the protection of adjoining properties.
3. 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 earthen-ware pipes, or cast-iron pipes protected against rust or corrosion by suitable asphaltic coating, and shall be so constructed as to be watertight 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.
4. All drains and sewers shall be laid so as to have a firm bed throughout their length. Where the bottom of a 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.
5. All stoneware 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.
6. That portion of the drain of any building which is immediately 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 and as near as may connected with such sewer. be practicable to the point at which such drain is 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 manholes and disconnecting chambers shall be constructed of brickwork at least 9" in thickness built in cement mortar so as to be watertight up to the level of adjacent ground and shall be fitted with manhole covers and frames to be approved by the Building Authority. If placed within a building such covers shall be air-tight.
7. 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.
8. Concrete for encasing drains or sewers shall be composed of four parts of good sound clean stone, broken to pass through a one inch ring, two parts of red or yellow earth and one part of lime thoroughly well mixed and well rammed into place or of such other materials and in such proportions as the Building Authority may approve.
9. Coment 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 Port- land cement and used fresh.
10. 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.
11. Subject to the limitation mentioned in the preceding regulation, no drain or sewer shall be larger than is necessary 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 Nos. 33, 34 and 35 of these regulations, shall be admitted to the drain.
12. Every drain 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 fall exceeds one in thirty the part of the drain or sewer, more remote from the public sewer, may be laid with a fall of one in thirty; 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.
13. Whenever the available fall for a covered drain or sewer is less than one in thirty 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 remaining portions.
14. Whenever the gradient of any portion of a covered drain or sewer is less than one in thirty, 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.
15. 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 of by the Building Authority and all such pipes shall be of a quality to be approved by the Building 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 building, and shall be imbedded and encased through- out its entire length in four inches of concrete as specified in regulation 8.
16. Whenever a covered drain or sewer traverses soft or yielding ground, or where water may make its appearance in the trench, the drain or sewer shall be surrounded throughout its entire length with four inches of concrete as specified in regulation 8.
17. No drain or sewer shall be constructed in such manner as to allow any inlet to such drain or sewer to be placed inside any roofed building, (except such inlet as may be necessary from the apparatus of any water-closet or urinal):
Provided that if in the opinion of the Building Authority it is impracticable to comply with this regulation in respect of any premises without encroaching on Crown land the Building Authority shall, on payment by the owner of such premises of a fee of $8, construct an inlet on Crown land to receive the drainage of such premises and connect such inlet with a sewer. The cost of cleansing and maintaining such inlet shall there- after be borne by the owner for the time being of the said premises and may be recovered by the Building Authority from such owner by an action in the Supreme Court in its Summary Jurisdiction.
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