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defective scavenging, whereby much dirt and even excreta are thrown into the drains through the gulleys; and partly to overflows or leakages from the Street Sewers. The first evil may be cured by improved scavenging, a question which will be dealt with in a subsequent section, and the second, by more efficient inspection of Sewers. I can cite a case, in support of the latter statement, which came to my personal knowledge. On visiting one of the open storm-water Drains, which had been constructed, from my designs, in 1890, I found that a stream of unmistakable sewage was flowing down its floor. This had been evidently going on for a considerable time, unknown to the officer in charge of the sewers. On examination, it was found that a manhole of a sewer above was blocked with dry-refuse, and that the sewage was overflowing into the nullah or drain. The trap, leading to the sewer-pipe, under the floor of the drain, was also plugged up with refuse. This incident supports the recommendations which I have made, to the effect that the maintenance of Sewers and Drains should be handed over to the Sanitary Board. An Engineer and one Inspector cannot possibly inspect a spread-out town, like this City, in an efficient manner. The Board, on the other hand, have numerous Inspectors, who are continually circulating, through the town, and who therefore could not fail to detect and report such an obvious nuisance, were it their duty to do so.
At present it is not their duty, and, naturally, they confine themselves to their business.
system of
be revised.
93. I understand that the amendment of the Drainage System has never been The whole considered, in a comprehensive manner. Probably this is due to the insufficiency drainage to of staff. Deviations and re-constructions have taken place, from time to time, and some improvement has doubtless taken place. From such plans as exist, it would appear that numerous Drains exist that are obsolete and useless; or at least could be made so, by some re-arrangement of the side-channels of the street. They were originally put in to serve as sewers, a purpose for which they are no longer required, on account of the construction of Sewers. It appears that, up to 1894, and even later, little was done to re-construct House Sewers, It was obviously impos- sible to connect an old House Sewer, one foot or more square, to a pipe. Therefore, some of the old Drain Sewers were allowed to remain, and still exist, notwithstanding the fact that they are no longer needed. I am, therefore, of opinion that the whole Drainage System should now be examined and surveyed and levels taken. This done, a comprehensive scheme of reform should be drawn up.
94. I can, with the information available, only describe the general principles Principles which should guide the design of drains or storm-water channels.
The most important point is to keep storm or surface-water on the surface. that is in the side-channels, to the utmost extent possible. So long as side chan- nels can carry the waters of a heavy storm, no covered drain should be permitted: It would be better to risk occasional inundation, than to have the permanent nuisance of a covere drain. At any rate, the covered Drains should be reduced to a minimum length. Some covered storm-water drains must always exist, notably those which traverse the City, from South to North, bringing down rain-water, from the hills above; the covered Nullahs, in short. These are fairly numerous, so that there should be no difficulty in bringing surface-water into them, by short lengths of covered drain. Some of the South-and North-running Drains might, in places be un- covered, even now. In cases where insanitary areas are resumed by the Crown
channels should, wherever practicable, be substituted for covered.
A proper arrangement of street will permit this to be done.
open
These covered Nullah drains, those running down through the town have, for the greater part of their length, ample gradients and keep clear of deposit, even with the normal dry-weather flow through them. From about Queen's Road to the Praya, they have necessarily flat gradients, and their inverts, though higher than they were, are considerably below high water mark. Consequently, the dry-weather flow is
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on which drains shouldi be designed.