656551-1890-Report-on-Separate-System-of-Main-Drainage — Page 31

THE HONGKONG GOVERNMENT GAZETTE, 27TH SEPTEMBER, 1890.

On page 49 of Mr. CHADWICK'S report, paragraph 11 reads as follows:-"Plates 1 and 11 show methods of draining some common types of houses according to the principles just enunciated. Provision is made for the removal of slop water only, but, as stated in the report, drains fit for that purpose are fit for the convey- ance of excreta also, so that when the time comes they can easily receive the additions necessary to fit them for this additional duty. No provision is made for removal of rain water which should be dealt with separately for the reasons stated in the report. The dimensions are, however, ample to receive a considerable quantity of rain, to carry off all would be clearly impossible."

At page 33, in paragraph 207 of the same report Mr. CHADWICK says:-"The upper portions of the existing sewers, those above Queen's Road, are, thanks to their great fall, rather than to their design and construction, almost wholly free from deposit. Nevertheless, it would be well to render their inverts water- tight, and to accelerate the dry-weather flow through them, by concentrating it in a semi-circular tile, laid on the invert."

Mr. CHADWICK evidently did not entertain a very high opinion of the old sewers.

960.]

961

Mr. LEIGH on page 7* of his report quotes a speech made by the Surveyor General on the 5th of Novem- [Gazette, p - ber, 1836, in which he stated that 4 miles of new sewers had been constructed and many other improvements carried out during the last three and a half years.

These new sewers above referred to are those constructed where previously open nullahs existed and extensions of the old system. The improvements have mainly been in connection with the main drains of the city among which I may mention, Gleneally, Peel Street, Eastern Street, Centre Street, Western Street and Middle Street drains.

There must still exist in the city many branch drains quite unsuited for the conveyance of sewage, any improvement to these necessitates entire reconstruction, and I would farther point out, as will be seen on looking at the plan, that no Government Sewer exists in some of the streets.

I am therefore of opinion that if Mr. CHADWICK had submitted a complete scheme it would have included many new sewers and at any rate to a considerable extent he would have adopted the "Separate System" for the drainage of the Chinese portion of the city.

Fever Commis.

1888.

On reference to the report of the Commissioners enquiring into the prevalence of fever in the Western Hongkong District I find on page XIV. the following:-" At the same time they would draw attention to the fact that son Report.. the withholding night soil from the sewers does not do away with the necessity for pipe-sewers. They would recommend the general adoption of pipe-sewers in addition to sub-soil and surface drainage." This report is dated 13th of August, 1888.

Mr. LEIGH proposes to use the existing drains for the conveyance of sewage and rainfall from the Chinese portions of the city and allow them to discharge as at present into the harbour, "but having no con- nection with the few large main storm-water drains, which convey the flood water from the hill sides above through the city."

Accompanying this report I forward a small plan on which I have shewn in blue "the few large main storm-water drains which convey the flood water from the hill sides above through the city." They are eleven in number and as will be seen from the Contours on the plan and as stated in my previous report occupy the principal valley lines, and are the main outfall sewers for the districts through which they pass.

It is evident that in the event of excluding the sewage from these and at the same time continuing to adopt the combined system of drainage for the Chinese portion of the city as proposed by Mr. LEIGH new sewers of considerable capacity must be constructed.

The other alternative is to intercept the storm water from the hill sides at or about the level of Caine Road and conduct it in new storm water drains to the harbour.

Now if the sewage and storm waters from the Chinese portion of the city are to be diverted from the existing drains it is clear that the circumstances favouring the deposit of material washed from the hill sides in the sewers will be materially increased.

On the other hand if the storm water from the hill sides above Caine Road be intercepted and diverted from the existing drains a considerable outlay will be involved and the risk of serious damage being done to property during heavy rainfalls increased. It would farther be necessary to improve some of the drains below Queen's Road to prevent the deposit of sewage matters in them.

I certainly contend it would be better to divert the sewage propor from the existing large drains by means of small pipe sewers as proposed in my report and farther as the system recommended by me provides for the construction of sewers in every street greater facilities for the disposal of sewage from private premises will exist than hitherto if this scheme is adopted.