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THE HONGKONG GOVERNMENT GAZETTE, 27TH SEPTEMBER, 1890.
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. L. L3. L^. L3. and Lo. which he recommends as suitable positions for the sewer outfalls 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 carried 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.
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
A. 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."
On page 32, paragraph 197 Mr. CHADWICK in his report says. "The outfalls of the present sewers are through the Praya wall into the harbour. Here the tidal current is weak at all times. No steps have been taken to carry out the sewage beyond and below low-water mark or to reach the tidal current. The inverts of 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 obvious 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 outweigh 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 24 hours, no rain having fallen, will be from 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 fall 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.
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On page 10* Mr. LEIGH quotes the following opinion of Sir ROBERT BAWLINSON sewers formed along steep gradients therefore require to have more care bestowed on the means of ventilation than other sewers laid
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