TẠI LÀM
CHUNG WATER
SUPPLY SCHEME
Extract from the report for the quarter ending 31st December 1953, by Mr. G.B. Gifford Hull, C.B.E., M.I.C.E., Chief Resident Engineer.
It is now just a year since the referred to in the last report have completed to permit the erection of Contractors started work on the dam. been continued both on blocks and the cableway. For the first 8 months work was beams, using about the same propor-
been sited at the lower end of the access road to Jubilee Reservoir; and in building a Stores for equipment etc. required for the treatment works
confined to the necessary prelimin- tion of crusher fines. and the results In addition the foundations and ary work such as access roads to have been satisfactory on both Class general works for crushers. conveyor both ends of the cableway, works C and Class A concrete.
belt, sand bins, cement silos and buildings, stripping soil from stone
The low heat cement now being
batching plant have been completed. deposits and opening up a quarry used preparing plant layout and doing the lower test results at 7 days than that is tunnels, filtration works, etc.. as specified, appears to give On the supply side of the work. Loundations for it etc., and in build ordinary cement. but increases by useful preparatory work has been ing the flume and the diversion wall
done, in making access roads to all to divert the river into it. When the over 100% at 28 days. river was thus controlled and the bed
the tunnel portals; levelling the hill Tests are regularly made for dry, excavation into the rock for watertightness on hollow cylinders, on which the treatment works are foundations of the dam and for the the pressure being put on externally sited to a general level of 360: wide- Tongue Trench upstream was start- in a machine devised on the works. ing the Castle Peak Road near Tsun ed. Good progress was made on this The cylinders are made with walls Wan Police Station to prepare for and in August it was possible to start 2" thick and the concrete is water- the laying of the 48" pipes between building the dam on excellent rock, tight under 200 lbs. per sq. inch, the outlet of Tunnel No. 3 and the satisfactorily tested for watertight- which is about 250% more than the Pumping Station; levelling the site ness. Concrete was first placed in greatest pressure to which the dam for the Pumping Station which has mid-August to form the diversion can be subjected when in service. tunnel through the dam. This was completed in December and on Christmas eve, the stream diverted through the tunnel. By the
In addition. surveys have been end of December the flume had been dismantled and the removal of the
made for, and lines set out for, tun- nels Nos. 2 and 3 and permanent ground on which it had been built
stations are now being established. was started. Good rock had already watertightness, have resulted. been reached on both sides of the
The decision to proceed with Stage During the period under review the II of the work necessitated increas- flume and the removal of this sec- Government made the decision to ing the capacity of the filtration tion, which is small in amount, will proceed with Stage II of the work works from 10 million to 20 million open up a good working area.
concurrently with Stage I. This gallons per day. The amended draw- The total amount of excavation in involves the construction of three ings, specification and Bills of dam foundations done during the subsidiary dams and the extension to Quantities have been received from year was 17,000 cu. yds. in soft and the main dam which brings its the Engineers and the Water Autho- 34.000 cu. yds. in rock, the latter maximum height to 200 ft. and its rity is now engaged on preparing being greater than the quantity length to cver 2.200 ft. Preliminary the documents necessary for inviting given in the Bill. The total amount surveys were made and borings tenders. of concrete now in the dam is over taken. and with this information 6,000 cu. yds. Plums from 4 ton to 2 centre lines for all the subsidiary tons in weight have been incorporat- dams have been selected. Final sur- ed in the Class C work, the overall veys for quantities are now in hand. percentage being about 18%. It
was
A method of testing the Expandite material specified for use in con- traction has been devised. using the above machine. and notably satisfac- tory tests for the tensile strength of the vulcanized joint.
and for its
The drawings of the Tunnels and pipe connections etc. between them were received in November. Some modifications were necessary follow- ing some re-siting of portals and the together with specification etc. and it is hoped that invitations to tender for the work can be issued in about 2-3 months.
could have been higher had the Construction plant for the dam Contractors had enough suitable began to arrive towards the end of new drawings are shortly expected.
plant. In fact concrete was placed with some struggle and difficulty be- cause of the lack of suitable plant, which is general over the job, and if this unfortunate fact is given due consideration, the year's progress cannot fairly be criticised. Suitable plant for dam building has not been available in the Colony.
the year.
and
Two crushers and two
were received. plate feeders parts of the cableway. Deliveries are expected to be complete by the end of January, when the cableway erec- The decision to proceed with Stage Meanwhile II of the work has removed many of tors are due to arrive. all the anchorages for the erection the difficulties in planning the work mast and for the permanent tail in relation to the future and has mast have been concreted, and greatly simplified it: and the cost of enough of the front and rear rail doing the extra work now will be less The tests on concrete and mortars tracks for the head tower has been than it would have otherwise been.
KAI TAK AIRPORT DEVELOPMENT
Report on Messrs. Scott & Wilson's Work during the quarter ending 31st December 1953.
During this quarter further con- lected from the sea-bed and in from the airport to the hill excava- sideration was given to the construc- particular a special piston sampler tion was put in hand, and initial tion of alternative airport schemes, was used successfully for obtaining consideration was given to a shor- and the costs of three such schemes undisturbed samples of the soft silt ter route to eliminate a long length were estimated.
in the Bay. The boring barges also undertook some work for the Public works Department at Yau Ma Ti. Causeway Bay, Gin Drinkers Bay and Ma Tau Kok.
The majority of work has been devoted towards collecting informa- tion for the initial contracts for the construction of the airport. In Kow- loon Bay two boring barges continu-
On land. a survey was completed ed to put down borings on the pro- of the hills north of La Salle College posed runway centre-line and in the that would be removed if the airport dredging areas. Samples were col- were built, the question of access
51
of the large nullah bordering Clear- water Bay Road.
In the soil mechanics laboratory testing of materials from the sea-bed has kept pace with sampling, and in particular a full series of tests have been started to assess the likely set- tlement in the layer of silt that would underly the airport reclama- tion.