WAINUI PIPE LINE.
QUESTION OF DUPLICATION.
The pipe-line from the Wainui Reservoir to town will probably have some attention given to it before the New Year is far advanced, and another effort will be made to have the line duplicated.
As far back as 1904, the City Engineer (Mr. W. H. Morton), in a report to the Council on the present pipe-line, advised that the main would be sufficient for five or six years. Mr. Morton’s time-limit has now been reached, and the extension of the City has meanwhile gone on to such an extent that something will have to be done in the near future.
The straightening of the Hutt railway-line was one of the works the City Engineer considered should be well on the way to completion before the new pipe-line was laid, and this work is now progressing towards completion. The new bridge over the Hutt River is also almost completed, so that everything appears to be ready for a final discussion of whether the duplication should not be gone on with.
In June last the City Engineer expressed the opinion that the time for the duplication of the main had arrived. As stated above, when it was proposed to undertake the work some years ago (1904), Mr. Morton reported to the Council, giving reason for postponement until about the present time, and the Council fell in with the report.
In the course of the report submitted in 1904, Mr. Morton made the following remarks:—
“In providing for either additional storage or mains, it is necessary to arrive at the present maximum daily consumption. The records of the Venturi meter show that during last summer the maximum draw-off the Wainui main per diem was not more than 3,000,000, and by measurement of the daily reduction in the level of the Karori Reservoir it can be seen that not more than 500,000 gallons per diem are supplied from that source; or a total of 3,500,000 gallons. Assuming the population now supplied to be 45,000, a maximum daily consumption is not more than 78 gallons per head.”
The report, after referring to the storage question, went on to say that the storage capacity recommended, viz., 219,000,000 gallons, would be sufficient at 78 gallons per head, for a population of 75,000 for 75 days, or at 60 gallons for a period of 144 days.
Regarding the inadvisableness of commencing the work of duplicating the Wainui main at that time, Mr. Morton said:—
“I consider the present Wainui main to be capable of delivering at Thorndon fully 5,000,000 gallons per day, against a pressure of 100lb to the square inch. If increased storage at Karori were provided, so that 1,000,000 gallons per day could be drawn from that source, the present mains supplying the City could be safely relied upon to discharge 6,000,000 gallons per day, which would be sufficient until the population is well over 60,000, until which time I have to recommend that the construction of a new main to Wainui be deferred.
“In making this recommendation, I am aware of certain risks that are run, through probable failure of the Wainui main, due to its being carried under three streams which are liable to scour, and which, in my opinion, should have been bridged over. At the same time, I think it inadvisable to lay another large main along the present Hutt Road if there is a prospect of the proposed new road being constructed within five or six years.”
