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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 reconstructiou, and I would further point out, as will be seen on looking at the plan, that no Go- vernment 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.
Sim Report, 1988.
On reference to the report of the Commissioners enquiring into the prevalence Hongkong Fever Coma of fever in the Western District I find on page XIV. the following:-" At the same time they would draw attention to the fact that 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 connection 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 rain- falls increased. It would further 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 proper from the existing large drains by means of small pipe sewers as proposed in ny report and further 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.
The natural slopes of the streets where no sewers now exist admit of the side channels being used for the conveyance of rain water to the existing main drains, so no new sewers for this purpose are required.
Mr. LEIGH has laid down on the plan accompanying his report points L1. La. L3. La. L3. and L. which he recommends as suitable positions for the sewer out- falls from the various districts marked Section 1, 2, 3, 4, 5 and 6 respectively.
A glance at the contour plan forwarded herewith shows that the ground in the western district slopes towards the west, so that practically the whole of the district west of Eastern Street is unprovided for unless an intercepting sewer is curried eastwards through the lower part of the city.
The same remarks apply to the position of the outfall L2. for Section 2. Mr. LEIGH contends on page 9 of his report there is no foreshore worthy of mention from Kennedytown to the City Hall.
* Plan not printed,
In his evidence given before the Commission enquiring into the prevalence of fever in the Western District. I find the following.
"909. But in front of each opening there is a decomposing mass.
A. There ought to be no foreshore allowed.
910. But there is
"
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4. It is a foreshore that has grown within the last few years. There are many bits of foreshore which I know did not exist when I came eight years ago. Very little dredging would suffice to remove them and the New Praya Scheme will put us out into deep water.'
"The outfalls 32. paragraph 197 Mr. CHADWICK in his report says.
Here the tidal of the present sewers are through the Praya wall into the harbour. current is weak at all times. No steps have been taken to carry out the sewage The inverts of beyond and below low-water mark or to reach the tidal current.
On
page
the sewer outlets are usually at, or near the level of low-water ordinary springs. Hence on a warm still day at low-water, the stench along the Praya is most offensive."
It is clear from the foregoing that 6 years ago the state of the foreshore on the Praya Front was such as led Mr. CHADWICK to take exception to it and I certainly consider the condition of the Praya Front at low-water decidedly a
nuisance.
A few months ago dredging operations were going on in front of the Harbour Master's Office the nuisance caused by stirring up the mud was obvions and showed that a considerable deposit of foul matters had taken place.
It must be remembered also that native craft are moored alongside the Praya for nearly its whole length.
Unless the Praya Reclamation is carried out I unhesitatingly recommend the construction of the outfall sewers I proposed.
If the Praya Scheme is finally decided on a question may arise whether the advantages to be gained ontweigh the cost of the construction of these outfalls.
The gradients of the outfall sewers are not unreasonably flat for outfall sewers. The large areas draining into them at the commencement of the flat gradients will ensure a sufficient flow in them to maintain a self cleansing velocity.
I estimate that the maximum hourly flow during each period of 21 hours, no rain having fallen. will be frout District No. 2 at the rate of 2,000 gallons per minute from District No. 3 at the rate of 800 gallons per minute and from District No. 4 at the rate of 1,200 gallons per minute.
Mr. LEIGH states during the Southwest Monsoon, especially when typhoons are in the neighbourhood, the sea level remains abnormally high for days together. I have been unable to find in the tidal records I have examined that the height of the sea level is such as to present any serious obstacles in the way of the satisfactory working of the sewers.
Mr. LEIGH objects to the syphons. On reference to the sections it will be seen good full has been, given to them and that they are laid falling to a manhole at their lower ends, under these circumstances and from past experience I consider his objections groundless.
On page 10 Mr. LEGH quotes the following opinion of Sir ROBERT RAWLINSON sewers formed along steep gradients therefore require to have more care bestowed on the means of ventilation than other sewers laid along flat districts. Every one who has had any experience in town sewerage is perfectly well aware of this and yet Mr. LEIGA recommends the rapid descent of the sewers from the high level district, in which he supports me in proposing the adoption of the Separate System, in preference to the more gradual descent of the high level intercepting sewer along Caine Road proposed by me and which unlike Mr. LEIGH's proposed outfall provides for the drainage of the whole of the district above the Caine and Bonham Roads.
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Mr. LEIGH takes exception to my evidence before the Fever Commission in which I stated I could not recommend at present any further ventilation of the sewers on the lower levels and claims the support of Sir ROBERT RAWLINSON. am quite ready to agree with Mr. Lon that ventilation improves the air in the sewers, but I contend that so long as many of the drains on private premises exist in their present condition no amount of ventilation of the main sewers would materially improve the air in the house-drains.
I fail to see Mr. LEIGH's contention on page 11 that efficient ventilation of the sewers would preclude the possibility of the sub-soil becoraing impregnated with
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