SURVEYOR-GENERAL'S OFFICE,
HONGKONG, 4th March, 1874.
74
95
No 44
7th March 1874
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I'm Arthun Kennedy, Resuly. CP.,
to
The Right Amorable
"The Earl of Shrinel anlay Simbalay.
Water Supply-
Transmits further Report of the Surveyor General upon-
SIR,
His Excellency the Governor has been pleased to put the question to me as to how far it would be possible to reduce the cost of carrying out my plans for sup plying Victoria with water from Tytam in the event of the Government deciding, after due enquiry, to reduce the daily allowance upon which I had based my calculations.
2.-In reply, I have the honour to state that since expediency compels the Government to contemplate a reduction of the proposed supply, it may not do better than limit the new Tytam works exclusively to the delivery of impounded water, abandoning the project of wayside feeders to the conduits. In other words, the latter may be limited to the carriage of 11 gallons per head daily from Tytani all the year round, instead of 11 gallons in the Winter, and 30 gallons Summer, as originally proposed by me.
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3.-The Tytam conduit was designed to accommodate the larger figure, viz., 30 gallons, but if it be now diminished from the dimensions given in page 20 of my report, to a waterway 18 inches square throughout, sufficing for 11 gallons, the saving effected in brick and cement, in stone work, excavation and concrete will amount to £13,099.
4.-In like manner the cast iron syphon pipes may be reduced from an in- ternal diameter of two feet to one of 18 inches, saving in tons weight of iron a value of £5,674.
5.-Applying the same reduced waterway to the tunnel work on the line, all subterraneau excavations
may be made one foot narrower, saving £1,885.
6. On reference to Appendix A., page 35 of my report, it will be seen that the estimate includes an item for the absorption of twenty-five tributary streams. It was the contents of the latter that were to have been utilized in swelling the allowance to 30 gallons during the Summer months, but if now tributary supplies are dispensed with, the item in question may be struck out, and an addional saving of £6,341 effected.
7. The Service Reservoir is a feature in the proposed scheme which may be regarded rather as a precaution dictated by prudence than a vital necessity. Its object was, to have continued the supply in the event of accidents and failures (liable to occur on a line of works 64 miles long) causing the supply to cease at any moment. But on such an emergency, it may, perhaps, be found preferable to trust to a reduced provision from the Pok-foo-lum subsidiary conduit while the breaches on the main line are being repaired, rather than incur the cost of a service re- servoir. If so, under this head alone £28,673 may be eliminated.
8.-The foregoing curtailments effect in the Tytam project an aggregate reduction of £55,670.
9.-It follows that the Pok-foo-lum subsidiary works forming a part of the original comprehensive project are open to a like reduction. The conduit may, like the Tytan one, be contracted into an 18 inch channel to serve the 4 gallons which the reservoir at present yields per head daily, thereby saving in excavation, brickwork, masonary, concrete and cement a sum of £9,424.
10.-A consequent reduction follows in the diameter of the cast iron pipes, and a saving in tons weight of iron equivalent to £547.
11.-Applying a proportionate reduction to the width of tunnel waterways, the retrenchment effected in sapwork is £355.
12.-The non-utilization of the twelve wayside feeders or streams mentioned in Appendix D of the report enables the expenditure of £3,044 to be avoided.
13. The foregoing savings on the Estimate of the Pok-foo-lum subsidiary project amount to £13,370.
14. The grand total of aggregate savings in the Tytam line, and the Pok-foo- lum subsidiary one, amount to £69,040.
The Honourable J. GARDINER AUSTIN,
Colonial Secretary.
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