Q 81
(d) Rapid Gravity Filters Eastern.
156. This work was referred to in paragraph 239 of last year's Departmental Report.
157. A tentative layout for this work was sent in July to Messrs. The Paterson Engineering Co., Ltd. who submitted preliminary drawings and specification for a plant with equipment for the chemical dosing of eleven million gallons per day and a filtration capacity of eight million gallons per day the latter to be supplemented later on by the removal and re-erection of the existing three million gallons per day filtration plant at Bowen Road. The official indent for this plant was submitted to the Crown Agents in October.
158. Enquiries were made through the Crown Agents in September for the supply of power and pumping units required in connection with this scheme but tenders had not been received by the end of the year.
(e) Kowloon Tsai Service Reservoir.
159. This work was referred to in paragraph 240 of last year's Departmental Report.
160. The excavation which involved the removal of 95,000 cubic yards of soft and 40,000 cubic yards of rock was practically completed by the end of the year. The main walls and invert of one half of the reservoir were completed, and the concreting of columns and roof had been commenced. As a result of experience on other works it was decided to vibrate the concrete in the walls, invert and columns and a contract was let to Messrs. The Hong Kong Engineering and Construction Co., Ltd. to vibrate the concrete placed by the main contractor.
161. In order to control the quality and density of the concrete mix, both the stone and sand were subjected to grading analyses. The stone was screened into three sizes and with two grades of sand being available, it was possible, by controlling the proportions of each grade used, to produce a well graded and dense concrete mix. With the graded mix and vibration excellent test results have been obtained. A 7 to 1 mix gave a density of 150 pounds per cubic foot, and a crushing strength of 5,000 pounds per square inch at twenty-eight days.
(f) Supply Main to Kowloon Tsai Service Reservoir.
162. This work was referred to in paragraph 241 of last year's Departmental Report.
163. Tenders for the supply of 24" diameter mild steel pipes and specials required for the rising main were called for locally and through the Crown Agents. The order amounting to £6,227-6-1, was placed locally with Messrs. The Hume Pipe (Far East) Ltd., which included the supply of the pipes and making welded joints in the field, the laying to be carried out departmentally. An order was also placed with Messrs. J. Blakeborough & Sons Ltd. amounting to £281-12-6. for the supply of sluice valves. Delivery of both pipes and valves was delayed owing to the war, and no pipes had been laid by the end of the year.
164. For the delivery main it was decided to use the old 18" diameter cross harbour pipes. This old main was successfully raised in a little over two months under contract by Messrs. Woo Hing for the sum of $11,654.00, which included the removal of the external covering of the pipes and delivering them in about 100 feet lengths on the sea front at Kowloon. The general condition of the recovered main was good except for a number of corroded areas where the protective brass tape was broken or displaced. In a few places corrosion had eaten through the 7/16" thick plate but on test it was found that the cement mortar lining prevented leakage.
165. Tenders were then called for the reconditioning of the pipes, cutting into lengths suitable for relaying on land, and rejointing in the new main. As the tender received was abnormally high and was thus considered unsatisfactory it was decided to execute the work departmentally. This work was satisfactorily completed by welding up corroded areas, and cutting into twenty feet lengths at a cost of about seventy cents per foot run of pipe.
Q 81
(d) Rapid Gravity Filters Eastern.
156. This work was referred to in paragraph 239 of last year's Departmental Report.
157. A tentative layout for this work was sent in July to Messrs. The Paterson Engineering Co., Ltd. who submitted preliminary drawings and specification for a plant with equipment for the chemical dosing of eleven million gallons per day and a filtration capacity of eight million gallons per day the latter to be supple- mented later on by the removal and re-erection of the existing three million gallons per day filtration plant at Bowen Road. The official indent for this plant was submitted to the Crown Agents in October.
158. Enquiries were made through the Crown Agents in September for the supply of power and pumping units required in connection with this scheme but tenders had not been received by the end of the year.
(e) Kowloon Tsai Service Reservoir.
159. This work was referred to in paragraph 240 of last year's Departmental Report.
160. The excavation which involved the removal of 95,000 cubic yards of soft and 40,000 cubic yards of rock was practically completed by the end of the year. The main walls and invert of one half of the reservoir were completed, and the concreting of columns and roof had been commenced. As a result of experience on other works it was decided to vibrate the concrete in the walls, invert and columns and a contract was let to Messrs. The Hong Kong Engineering and Con- struction Co., Ltd. to vibrate the concrete placed by the main contractor.
161. In order to control the quality and density of the concrete mix, both the stone and sand were subjected to grading analyses. The stone was screened into three sizes and with two grades of sand being available, it was possible, by controlling the proportions of each grade used, to produce a well graded and dense concrete mix. With the graded mix and vibration excellent test results have been obtained. A 7 to 1 mix gave a density of 150 pounds per cubic foot, and a crushing strength of 5,000 pounds per square inch at twenty-eight days.
(f) Supply Main to Kowloon Tsai Service Reservoir.
162. This work was referred to in paragraph 241 of last year's Departmental Report.
163. Tenders for the supply of 24" diameter mild steel pipes and specials required for the rising main were called for locally and through the Crown Agents. The order amounting to £6,227-6-1, was placed locally with Messrs. The Hume Pipe (Far East) Ltd., which included the supply of the pipes and making welded joints in the field, the laying to be carried out departmentally. An order was also placed with Messrs. J. Blakeborough & Sons Ltd. amounting to £281-12-6. for the supply of sluice valves. Delivery of both pipes and valves was delayed owing to the war, and no pipes had been laid by the end of the year.
164. For the delivery main it was decided to use the old 18" diameter cross harbour pipes. This old main was successfully raised in a little over two months under contract by Messrs. Woo Hing for the sum of $11,654.00, which included the removal of the external covering of the pipes and delivering them in about 100 feet lengths on the sea front at Kowloon. The general condition of the recovered main was good except for a number of corroded areas where the protective brass tape was broken or displaced. In a few places corrosion had eaten through the 7/16" thick plate but on test it was found that the cement mortar lining prevented leakage.
165. Tenders were then called for the reconditioning of the pipes, cutting into lengths suitable for relaying on land, and rejointing in the new main. As the tender received was abnormally high and was thus considered unsatisfactory it was decided to execute the work departmentally. This work was satisfactorily completed by welding up qorroded areas, and cutting into twenty feet lengths at a cost of about seventy cents per foot run of pipe.
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