Sub-Enclosure to Enclosure in Despatch No.
of the 1st. July, 1908.
#78
509
Hongkong, 16th. June, 1902.
The Honourable
Chatban,
Director of Public Works.
118
Dear Sir,
K. W. # Gravitation Scheme.
We have considered Mr. Chadwick's recommendations forwarded with yours of 11th. instant and beg to report thereon as follows:-
1. Proportions of Concrete. We have this question in hand and as soon as the 9" cubes are made will report to you on the matter.
2. Drainage of foundation and body of Dam. We see no objection to Mr. Chadwick's proposals.
3. Outlet Arrangements. We will bear Mr. Chadwick's proposals in mind when the time comes to indent for these.
4. Venturi meters to measure supply. Arrangements will be made for these when designs for filter beds and Service Reservoir are got out.
5. Gauges to measure flow of stream during construction of dam. It is doubtful if the self-recording indication could be got out from home and fixed in less than 18 months. (Plain C. I. pipes ordered in August last have not yet all arrived). It is hoped that the Dam will be completed within 3 years, and consequently the gauge would be in use for probably little more than 18 months. We do not think that records for so short a period would justify the expense. Further, such records if obtained would not give a detailed indication of the flow off the catchment area, but only a measure of the total yield, as the filling of the reservoir will average the flow. And we doubt if it would be possible to avoid injury to such gauges during floods, with the water flowing over a masonry dam in course of construction immediately behind them. And lastly, we would point out that the catchment waters for the supply of the reservoir will probably be incomplete during part of the period and consequently the drainage area a variable quantity. On these grounds, we think it would be advisable to reconsider this proposal.
6. Roofing of Service Reservoir. Alternative designs will be made as suggested and the cheaper adopted.
7. Intakes on pipe tracks. These are now in course of construction.
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