197
Jervoir acity.
(4)
...
The Director of Public Works Paragraph 12 section 2, This, I presume brings, "Catch-water" is mentioned.
in the water from some area, amounting to 400 acres, not shown on the plan, and therefore making a total of about 800 acres. Applying to this area the Hong Kong data, quoted in my report of 17 August 1900, the available daily supply would be 1,488,000 gallons a day, an amount agreeing substantially with that estimated by the Director of Public Works, namely, 1,575,000 gallons a day.
(4) According to the same data, a reservoir capacity equal to 200 days' consumption will be required to maintain the supply. The now proposed reservoir is to contain 310 millions of gallons, so that, according to Hong Kong experience, it should suffice to maintain the desired supply.
(5) I am glad to learn that it is now proposed to construct a masonry dam. I do not consider that it would be safe to construct an earthen dam, of the height nearly 100 feet.
Indeed I hold the opinion, now proposed, one shared I believe by most Engineers, that masonry (including concrete) should be preferred, whenever the conditions for its use are reasonably favourable.
(6) The section of the masonry dam is judiciously designed. I have investigated the stresses, and I find that the conditions of stability, usually accepted, are fully satisfied, even when the reservoir is full to the very crest, in other words when the water-level, during a great flood is 4 feet above the sill of the waste weir.