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6
Classification of drains.
Tidal section
of nullahs. Levels of inverts.
matter is one that the Sanitary Board and the occupier should decide. The Board has doubtless powers to compel owners to abate nuisances. Matters would be simplified if, as recommended, the Sanitary Board has charge of the scavenging of nullahs. In the case of new houses, this difficulty will practically disappear if the rules set forth in the Standard Instructions which I propose to send out are observed.
DRAINAGE.
I have little to add to what I have said in my previous Report concerning the Drainage of the City. Before anything can be finally suggested a complete plan must be prepared of the drains and nullahs as they exist.
·
The following suggestions may, however, be of use in the future consideration of this subject.
16. Drains may be classified as follows:-
(4.) Main drains or nullahs running direct down to the sea and carrying
water from the hills above.
(b.) Branch drains which run usually more or less in an East and West direction and convey water into the main drains or nullahs above defined.
The aforesaid main drains or nullahs may be further sub-divided into two portions, namely, the flat or tidal portion which extends perhaps to Des Voeux Road or further inland and the hill portion which has an abundant gradient.
17. The following statement gives the levels of the several nullahs at their outfalls as determined by Mr. XAVIER, Assistant Engineer, and the attached plan No. 7 shows the distances to which the sea-water backs up along the inverts at mean high-water and mean sea level respectively. It will be seen that the nullah- outlets have their inverts well below mean sea level and those of many are below ordinary low-water mark. Consequently these nullahs contain at their lower end, where they cross the Praya Reclamation, stagnant water contaminated by filth brought down from above as well as matter washed in by the tide.
City of Victoria, Hongkong.-Out-falls of Nullahs.
Locality.
Size.
Invert of Out- falls referred to Ordnance
Remarks.
Datum.
Belcher's Point,
2' 6" x 2′ 6"
1.37
Whitty Street,
I' 9" x 1' 6"
0.35
West of Marine Lot 205,
1' 6" x 2' 6"
0.41
Near outfall still in-
complete.
French Street,..............
2′ 0′′ × 1' 6"
0.45
Western Street,
4' 6" x 4' 0"
1.70
Centre Street,
4' 6" x 4' 0"
1.28
Eastern Street,
2′ 0′′ × 3′ 7′′
0.39
Wilmer Street,
2' 0" x 3' 7"
0.35
Sutherland Street,
2' 0" x 3' 6"
1.21
Queen Street,
6′ 6′′ × 4′ 6′′
0.27
Wing Lok Street,
dia: 18"
0.16
West of Marine Lot 225,
dia: 15"
0.98
Cleverly Street,
7′ 6′′ x 5′ 4′′
0.07
Hillier Street,
dia: 15"
0.65
Toong Kai,
dia: 18"
0,57
Wing Wo Street,
Gilman Street,
3′ 5′′ × 2′ 3′′
1.14
7′ 6′′ × ′ 3′′
1:56
Jubilee Street,.
7' 6" x 4' 3"
1.11
Pottinger Street,.
3' 6" x 1' 6"
1.00
Douglas Street,
2′ 6′′ × 1' 6"
2.63
Pedder Street...........
5' 0" x 3' 6"
0.62
5' 3" x 4′ 0′′
0.09
Invert-level
of nullabs
been fixed
Ice House Street,
18. There can be no doubt that it would have been better to have fixed the should have inverts of the nullah outlets at or about mean sea level, so that they could be dry- scavenged daily. Why this was not done cannot now be ascertained. I fear that it is now fully late to effect any radical cure of the undoubted evils of the tide- locked nullahs. Some abatement might be effected by diverting the ordinary dry-
higher.