Sessional_Paper_1902 — Page 556

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As to the

nature of the deposit in

sewers.

As to the manner in

which the

free from obstruction or deposit. There is, however, a tendency to deposit in the flatter sewers, those running along Queen's Road, and across and along Des Vœux Road and new Praya; so much so that it is thought necessary to pass a scraper through them, periodically, as a matter of routine. Such is also the case in the sewers along Garden, Robinson and other Roads, but there the obstruction is chiefly due to the entrance of roots, generally of the Banyan tree.

The only way to remedy this is either to do away with the trees, or put in cast-iron pipes. Trees in a town are a nuisance and should not be permitted. Of all trees for such purposes the Banyan is one of the worst. The roots of plants of the fig tribe grow with surprising rapidity, and have great power of penetration.

The occurrence of deposit in the low-level sewers is not as it should be. The gradients of the sewers in Queen's Road and Des Voeux Road are good, and there is an abundant flow of sewage through them. Those on the new Reclamation must be regarded as temporary only. Levels recently taken by Mr. XAVIER, give evidence of considerable settlement. The centre lines of the sewers, at the outlets, are materially lower than originally projected (mean sea level or 3.70 O.D.), appar- ently owing to settlement. Consequently, these sewers are tide-locked for a larger proportion of the year, than was intended, and therefore there are longer periods of stagnation than is perhaps desirable. The sewers on the Reclamation will therefore require re-construction. It does not seem desirable however to do so forthwith. It will be better to wait until the Reclamation works are not only completed, but also fully occupied by buildings; when the soil will be so far consolidated, that fur- ther movement will be improbable. For reasons which I shall give in the next paragraph, the accumulation of deposit in the low-level sewers, is a cause of expense, rather than a danger to health.

66. I have examined the deposit, which was being removed from a sewer on the Des Voeux Road. It certainly was not sewage deposit, which is a black, fœtid, semi-fluid substance. It was composed of coarse sand or grit, broken glass, small bottles, bits of joss-sticks, and the like, stained black by sewage. It was moreover nearly inodorous. Moreover there was little smell, from the manhole. Clearly, the deposit is not due to the sewage proper, but to solid matter, which ought not to have found its way into the sewers. I am informed that the sample which I saw, was typical in character.

67. It is not easy, to discoyer, exactly, the manner in which so much detritus finds its way into the sewers. Some, doubtless, is put in by the inhabitants, to save themselves the trouble of removing it from their back-yards, through the to the sewers. house, often through a well-furnished shop.

solid matter

finds its way

There is also evidence to show that the scavengers occasionally open sewer- manholes and throw dry refuse into them and into the gulleys. This is aggravated by the improper construction of the gulleys, both sewer and storm-water. The scavengers also, when washing down the gutters sweep much detritus into the gulleys, which ought to have been removed by dry scavenging. It is obviously to the interest of the scavenging-contractor to dispose of as much refuse, in this way, as he can, and so to save the expense of removing it by boat, the more so, because. unlike excreta, the refuse has no market value.

These inconveniences are seriously aggravated by the division of authority hich exists. The sewers are under the control of the Public Works Departinent, whilst the scavenging is directed by the Medical Officer of Health. I shall revert to this matter later on. It seems certain therefore that Mr. COOPER was right in stating, as he always did, that the accumulation of deposit in the low-level sewers was due to the introduction of matter which should never find its way, in any quantity, into a sewer, and which no sewer could, under the circumstance, be expected to carry off.