THE HONGKONG GOVERNMENT GAZETTE, 27TH SEPTEMBER, 1890. 931
GOVERNMENT NOTIFICATION.--No. 404. The following Reports are published for general information.
By Command,
Colonial Secretary's Office, Hongkong, 27th September, 1890.
W. M. DEANE, Acting Colonial Secretary.
REPORT ON THE SEPARATE SYSTEM OF MAIN-DRAINAGE. (Plans accompanying this Report are not printed.)
PUBLIC WORKS DEPARTMENT,
HONGKONG, 24th August, 1888.
SIR,-I have the honour to transmit you the enclosed preliminary Report of Mr. F. A. COOPER, on the Separate System of main-drainage for the city of Victoria and to recommend his propositions to the favourable consideration of His Excellency the Governor,
2. The adeption of the Separate System will be in harmony with the drainage provisions of the new Publie Health Ordinance.
3. The main features of the Project are four, viz. :--
(1) The dissociation of the sewage of houses from storm-waters.
(i.) The rapid conveyance of the town-sewage to the sea and its innocuous disposal in the tidal current by means of separate glazed stoneware drain-pipes of a bore comparatively small because of the elimination of storm-waters.
(iii.) The admission of a limited proportion of rain-fall into these proposed foul water drains; and
(iv.) The escape of storm-waters and sub-soil drainage into the sea as heretofore through the present main
drains of the city which remain undisturbed.
4. The dissociation of house-sewage from storm-waters will so greatly reduce the volume of foul water to be dealt with, and will make that volume so manageable as to enable small diameters to be used for the principal arteries, and due to this circumstance the project will be feasible at an outlay that is moderate compared with the relative expense that would attend the construction of the same length of main sewers under the Combined System which requires-in consequence of our heavy rain-falls--that all chaunels be of an unduly large and costly size. The estimated cost of the four proposed new foul water mains comprised in this schome, together with their branches and all contingent works amounts to $230,000, but as the eastern district of Victoria is found to be nearly ou a dead level and as it is found impos- sible to give the proposed eastern main a gradient or inclination sufficient to induce a self-cleansing velocity, it will be necessary eventually to dispose of the sewage of Wantsai and Bowrington at some additional outlay by conveying it as far east as North Point where the tidal scour is at its greatest and there establishing a steam-pumping station, an expedient commonly resorted to in English towns similarly circumstanced. These extra works are estimated at $113,000 making the total cost $343,000.
5. The establishment of the Separate System of drainage will in no way nullify or minimize the importance of the main drainage improvements which have been effected by the Government from year to year during the last ten years, for even if house-sewage is now diverted to special channels of its own, properly built rain water drains of adequate sectional area and laid to proper falls are none the less a necessity to the city for the removal of sub-soil drainage and storm-waters.
6. The Separate System can be carried out without adding to the expense of house-owners, for it will impose no greater burthen on the landlord to connect his house-drain with a Government main sewer under the Separate System than with one under the Combined System. Two house-drains-one for dirty water and one for rain water-will not be required of Lim. His roof drainage and the rain which falls upon his back-yard may in most cases be allowed to escape over the surface through gutters into side-channels, and thence into the nearest of the numerous street gratings which everywhere communicate with the storm-water drains.
7. The Separate System of drainage is no new experiment in European cities. As its advantages are brought to light by practical experience it is becoming every year more generally adopted by Municipal and other public Bodies. To Hongkong, if not adaptable before owing to the inadequacy of the public water supply, it will be specially adaptable now for the first time that we have a new reservoir admitting of a daily consumption of water in every house in the town sufficient to afford the drains in the shape of waste waters that volume of dry weather flow throughout the winter which is essential to the effective working of a system that seeks to act in a measure independently of rain.
8. Though Mr. COOPER's Report relates principally to main drainage I wish to invite His Excellency's special attention to that portion of it wherein he refers incidentally to house-drains for it is impossible to overestimate the importance of remedying as early as possible the evils to which he alludes.
9. Up to the passing of the new Public Health Ordinance (Ordinance No. 24 of 1857) the law on this branch of practical sanitation was inadequate for securing efficient house-drains. The Statute Book contained no provisions for the class of materials to be used in their construction, nor yet did it prescribe the method of that construction, nor were there any provisions for trapping, ventilation, or disconnexion. The result of this inadequacy of the Law was that the