Sessional_Paper_1902 — Page 555

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21

between Mr.

project of

that of 1890.

Western and

61. The leading differences between the Sewerage Project of 1888 and that of Difference 1890 occur in the number, position and levels of the out-falls. Designing before CoOPER'S the Reclamation works were commenced, when the fore-shore was relatively shallow, 1888 and and irregular on plan, Mr. COOPER proposed three principal out-falls, namely, at Belcher's Point, Possession Point, and a third, near to the Bowrington Canal. This, however, he regarded as temporary only, and suggested the ultimate prolong- ation of this section of sewer to North Point; where a pumping-station was to be provided.

The gravitation out-falls were to be laid at about Low-water mark, Spring Tides. As, however, the new Praya was to be constructed in deep water, and with a regular alignment, along which there would be a strong tidal current, I proposed to provide five out-falls, for the Western and Central Districts, constructed in the face of the new Praya wall, sewerage being carried out into deep water. By increasing the number of out-falls, it became possible to increase the gradients of the sewers.

The out-fall levels were raised. The centre-line of the out-fall was to be fixed at mean sea level, instead of low-water-mark, Spring tides, so that the sewer would be free from tide-water, for one-half the year, instead of for a short time only as would be the case with an out-fall at extreme low-water mark. As regards the street sewers, there is no difference, in principle, between the two projects.

Central Distri- ts.

schemes for Eastern

62. As regards the Eastern District, Mr. COOPER proposed a temporary out-fall, Differences at the Bowrington Canal; but ultimalely to intercept the sewage of the whole dis- between trict from the harbour. I proposed also to effect interception, by a different arrange- Distt. ment however. In lieu of a deep sewer, I proposed to use a cast-iron syphon pipe. As regards this section of the town also, there was no difference, in principle, as regards street-sewers.

executed.

tricts.

63. As far as can be ascertained, in the absence of complete and distinct record- The works as drawings, the works of the Western and Central Districts have been carried out, in Western and accordance with the report of 1890. I may here say that much difficulty and Central Dis. delay has been caused, with regard to my present work, and that great inconvenience is caused to the several Departments concerned with Sewerage and Drainage, by the absence of complete, up-to-date, record-drawings. This want is, doubtless, due to insufficiency of Staff, for Mr. COOPER is far too careful a man to neglect to have proper records, if he had the means of making them.

It may be safely asserted however that such is the case, in all matters of prin- ciple. Some slight alterations in detail may have been made. The whole of the out-falls and some sewers on the Reclamation have not yet been completed, on account of the non-completion of the Praya Reclamation works.

Eastern

64. The proposed arrangement for the interception of the sewage of the works Eastern District, has not been carried out. The sewage is admitted to the har. esecuted in bour, by numerous out-falls not extending to low-water mark. The reason why District. interception was not carried out was, I believe, as follows. Then, as now, the reclamation of this fore-shore was contemplated. It was therefore considered that, if out-falls on the New Praya wall were permissible, they could also be adopted, in the case of the Eastern Reclamation, thus saving the cost of the intercepting- syphon, as well as that of pumping: at any rate, it was not thought well to attempt inter-ception, until something had been settled concerning the future of the foreshore.

As regards the street-sewers of this district, they have been executed in virtual accordance with the project of 1890.

65. I am of opinion that the Sewerage System is working well, especially wher the scarcity of water is considered.* All the sewers in the higher districts h excellent gradients and, with the normal flow of sewage, even now, keep themselve.

* Saving and exepting the defects hereinafter set forth; some of which are due to improper use rather than to detective design or construction.

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