TẠI LÀM CHUNG WATER SUPPLY
SUPPLY SCHEME
Extracts from the Quarterly Report of the Chief Resident Engineer.
Mr. G.B. Gifford Hull, C.B.E., A.M.I.C.E.
In the P.W.D. quarterly progress report proportion of the mass work must be
on major works for the quarter ending 30th placed to complete Stage I. On the left September 1955, there is included a full bank the front face was behind hand but report on
the Tai Lam Chung Water the first lift has now been placed up to Supply Scheme by the Chief Resident 300 L. Mass work can now be carried out Engineer. From this report, which covers from blocks 3 to 15 inclusive, covered by every phase of this vital and important the present layout of the three derricks. work, we quote the following notes which we feel will be of particular interest to everyone in Hong Kong.
Certain important aspects of the work have shown valuable progress during the quarter in spite of the disappointing total volume placed. A considerable advance of both Hanks of the dam has been made; the soft seam on the right bank has been cleared and concreted up to 280 R; pro- gress has been made with the wet well: the caulking of the front face masonry joints is now properly organized, and at the extension the special 4 ft. cut-off trench bas been completed and concreted.
The high quality of all classes of con- crete has been maintained,
The advance of the front face of the dam into both flanks has been the best feature of the period. On the right bank the first lift of face concrete has been placed up to 270 R and this, together with the filling of the seam up to 280 R will mean a greatly increased area for concreting on this side where the larger
View of the Dum showing the AC ROW Steri Scaffolding in use for the first time in the Colony, under most difficult con- ditions and giving every satisfaction.
The bottom intake culvert was complet- ed and the wet-well concreted to level 106 A.P.D. At this level the granite masonry face starts and there has been several weeks delay while the contractor argues with the masonry sub-contractor over the cost of the work. The first stones have just been received.
The gallery has been cleaned out and good progress made with concreting the floor, steps and under-drainage channel.
The total quantities of work done up to the end of September are shown below : Dam
Excavation
31,700 cu. yd. 64.700
soft rock
Tongue
Trench
5,100
6.716 3.928
H
Concrete Class A Concrete Class B Concrete Class C
with plums 22% Masonry Extension
Excavation in trench Concrete Class A
Concrete Class B
Filling
Low Gap 1. Excavation
Low Gap 2.
Low Gap 3-
86,950
54.500 sq. ft. Photograph of the sloping face of Tai Lam Chung Dam, The Major Contractors, Ltd., a local firm, are carrying out the work.
5.400 cu. về. 3.830 18
22,000
+
creted and plans approved for the larger one on the right flank.
2,050 cu. yd, General:
300 1,000
Trench excavation has continued, 550 cu. yd. being moved in the quarter. Rock has been exposed on the left flank and on part of the right flank. Near the road. however, a more or less vertical soft seam
has been encountered and this is being followed down. The present depth is 40
Since the uncertainties regarding the extent of the work necessary to deal with You will note that the total quantity the seam on the right bank are ended it of concrete now placed is just short of has been possible to estimate quantities 100,000 cu. yd. i.e.
two thirds of the and time required to bring the flanks of original contract quantity for Stage I, and the dam up to level 160 and the central a little over half of the amended quantity. part to about 150, and to make a forecast Low Gap Dam No. 1
of when it should be possible to close the diversion tunnel and begin to bring the water up. This shows that it ought to be possible to begin to fill in May or June next year, which is rather earlier than I once thought. The decision as to whether Director of Public Works and, I presume. to start filling or not will rest with the
will depend on the general supply position. But as impounding cannot start until villagers in the reservoir area are movel Work on the above started On
11th and re-settled. I have informed the Dis- August. 1955. Trench excavation in soft trict Commissioner. New Territories, of material amounts to 300 en. yd. to date. the possible date for commencing to fill,
so that he can take the required action. Low Gap Dam No. 3.
The major part of the labour force, which Although the Supply Works may not be has now risen to about 140, is working on entirely finished by the time water has this site.
it would seem ex- Trench excavation is in pro- reached 150 level gress right across the valley except for a pedient to store the 1956 water if possible. small length and 1,000 cu. yd. have been not only to have it available in case of moved to date. A compressor and tools emergency, but because otherwise there are in use on the rock which is encounter will be no water behind the dam till late
ft.
Low Gap Dam No. 2.
ed at fairly shallow depths in places. The 1957, by which time all the Supply Works catchwater on the left flank has been con- will be waiting for it.
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