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the Eastern one draining an area of twenty acres elevation of approximately 400.00 A.O.D. and discharging into the East Catchwater near its outfall to the Aberdeen Upper Reservoir. The Western Section drains an area of 28 acres at an elevation of approximately 280.00 A.O.D. and discharges into the Aberdeen Lower Reservoir. Both sections have been designed to collect a maximum rainfall of two-thirds of an inch per hour and overflows have been designed to discharge any excess over this figure up to a maximum of 4" of rainfall per hour.
208. Existing Dam Alterations-Preliminary Investigation.-- This work was referred to in paragraph 277 of last year's Report. The existing catchment area of the old Paper Mills Reservoir, now known as the Aberdeen Lower Reservoir, being considerably increased under the Aberdeen Valley Scheme and the existing dam being in a dilapidated condition, it was found necessary, in order to retain the existing storage of the Reservoir and also to provide adequate facilities for discharging the increased flood water, to carry out extensive alterations and modifications to the existing structure. The contract was satisfactorily completed by Messrs. Foo Loong & Co. on April 2nd, and the retention money was paid during the year.
209. Reconstruction of Lower Dam.--A contract for this work was let to Messrs. Kin Lee & Co. on 4th April for $93,834.90, the contract time being eight months. The works progressed so well, however, that impounding in the Reservoir for supply purposes commenced on 23rd September, about twelve million gallons being collected to the end of the year, and the contract was completed on 1st November--thirty-five days under the time allowed.
The old dam, which was of the buttress type, had a length at road level of 440 feet, a maximum depth below overflow level to stream bed of sixty-three feet, and was provided with one 9" draw-off and one 18" washout, each being controlled by a single sluice valve on the up-stream face and exposed to the water. The length of the overflow, at a level of 261.85 A.O.D. and which was continuous over the main section of the dam, was 110 feet. Access across the top was made by means of light steel trestles supporting timber bearers and planking. The old dam was constructed of various grades of displacer concrete, generally of poor quality in the interior, with better material near the faces. The whole of the facing was of hard blue rubble set in cement mortar.
The reconstructed dam is of the gravity type throughout, the construction of which necessitated the cutting away of parts of the old buttresses and filling in the spaces between them, so that the down-stream face now presents a uniform appearance. The new overflow, at a level of 263.50 A.O.D., was formed by
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the Eastern one draining an area of twenty acres elevation of approximately 400.00 A.O.D. and discharging into the East Catchwater near its outfall to the Aberdeen Upper Reservoir. The Western Section drains an area of 28 acres at an elevation of approximately 280.00 A.O.D. and discharges into the Aberdeen Lower Reservoir. Both sections have been designed to collect a maximum rainfall of two-thirds of an inch per hour and overflows have been designed to discharge any excess over this figure up to a maximum of 4" of rainfall per hour.
208. Existing Dam Alterations-Preliminary Investigation.-- This work was referred to in paragraph 277 of last year's Report The existing catchment area of the old Paper Mills Reservoir. now known as the Aberdeen Lower Reservoir, being considerably increased under the Aberdeen Valley Scheme and the existing dam being in a dilapidated condition, it was found necessary, in order to retain the existing storage of the Reservoir and also to provide adequate facilities for discharging the increased flood water, to carry out extensive alterations and modifications to the existing structure. The contract was satisfactorily com- pleted by Messrs. Foo Loong & Co. on April 2nd, and the retention money was paid during the year.
209. Reconstruction of Lower Dam.-A contract for this work was let to Messrs. Kin Lee & Co. on 4th April for $93,834.90 the contract time being eight months. The works progressed so well, however, that impounding in the Reservoir for supply purposes commenced on 23rd September, about twelve million gallons being collected to the end of the year, and the contract was completed on 1st November-thirty-five days under the time allowed.
The old dam which was of the buttress type had a length at road level of 440 feet, a maximum depth below overflow level to stream bed of sixty-three feet and was provided with one 9" draw-off and one 18" washout each being controlled by a single sluice valve on the up-stream face and exposed to the water. The length of the overflow, at a level of 261.85 A.O.D. and which was continuous over the main section of the dam, was 110 feet. Access across the top was made by means of light steel trestles supporting timber bearers and planking. The old dam was constructed of various grades of displacer concrete, generally of poor quality in the interior with better material near the faces. The whole of the facing was of hard blue rubble set in cement mortar.
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The reconstructed dam is of the gravity type throughout. the construction of which necessitated the cutting away of parts of the old buttresses and filling in the spaces between them so that the down stream face now presents a uniform appearance. The new overflow at a level of 263.50 A,O.D, was formed by
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