Dam No.2.
Dam B.B.
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I estimate would cost $4,200,000 to construct giving a unit
rate of $4,200 per million gallons.
Dam No.2 or Shing Mun Gorge Dan. The Shing Mun
Gorge has all the appearance of a most excellant Dam Site
but on closer inspection it has not been found so favourable,
as there is a rather steep fall in the river bed at this
point. The capacity of the reservoir is also disappointing
owing to the basin being very narrow with almost precipitous
sides.
A Dam with a Top Water Level of 565 A.O.D. would
impound 1,000 million gallons and would cost approximately
$2,500,000 to construct giving a unit rate of $2,500 per
million gallons.
Comparing the above two dams it is seen that the
unit cost per million gallons of Dam No.1 is very much
greater than the cost at Dam No.2 and both work out fairly expensive in comparison with existing reservoirs.
Owing to the great fluctuation of the annual
rainfall, from a minimum of 46 in. to a max. of 120 in., the
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quick run off of this catchment area and the fact that this is gravity water it would appear desirable up to a point to get as large storage capacity as possible.
With this object in view and also to eliminate if
possible Dam No.1 or Shing Mun Village Dam owing to its
excessive cost, I have taken out estimates for Dams at the
Gorge on Lines B.B., C.C. & D.D. shown on Drawings Nos.2 & 3
and each having a Top Water Level of 600 A.0.D.
Dam on line B.B. would have a maximum depth of
water of 200 ft. a max. depth to bottom of foundations of
270 ft. and impound approximately 2,000 million gallons.
I