Ashlar masonry of inner face and of overflow section of outer face, Rubble masonry of outer face, except overflow section,
Ashlar masonry in string courses, cor-belling courses, parapets, culverts, valve-house, etc.,
P.W.E. Hongkong.
164,858 cub. ft.
59,400
$3,361
""
The valve-tower contains two wells, each 12′0′′ × 8′0′′, which connect at the base of the dam with two culverts, nearly circular in section, their diameter being 12 feet and their height 10 feet. Each well contains a stand-pipe, 18" diameter, from which draw-off pipes (15" diameter) connect with the reservoir. The draw-off pipes are at intervals varying from 10 to 15 feet, connected alternately with each stand-pipe. The stand-pipes are connected with 18" supply-pipes leading to the pumping station. At the outer end of the culverts is the outlet block containing a system of valves which enable either stand-pipe to be connected with either supply-pipe. Valves for controlling the draw-off pipes are contained within the valve-wells and external penstocks are provided for cutting off the water in the event of damage to any valve or pipe. Below each culvert, there is a wash-out pipe 21 inches in diameter, the valves for which are also contained in the valve-wells. By means of a connection with one of the wash-out pipes, provision is made for drawing off the water in the reservoir to a depth of 10 feet below the lowest draw-off pipe thereby increasing the effective impound by 38 million gallons. The valve-wells and culverts are faced throughout with granite ashlar. A valve-house, 31′0′′ × 10'0" internally, containing the valve-operating gear, surmounts the valve-wells. The house is built entirely of granite ashlar and is roofed with reinforced concrete. The floor of the valve-house and the platforms in the valve-wells, with the exception of those supporting the head-stocks, which are of cast-iron, are of reinforced concrete, made in removable slabs.
X
The roadway over the dam has a clear width of 16'6" between the parapets, which are of ashlar masonry in bays of alternate rock-faced and rough-punched stones, surmounted by a rock-faced ashlar coping. It forms part of the main road encircling the greater part of the Island of Hongkong, which is now being adapted for motor traffic. The overflow crest of the dam is 240 feet in length, the roadway being carried over it on 12 arches each of 20 feet span. The arches are of reinforced concrete faced with ashlar masonry and are supported on piers of ashlar masonry, the stones of which are bonded together with steel rods.
At the base of the dam, there is a water-cushion extending for a length of 153 feet, into which the overflow water is conducted by flood-water channels. The water-cushion discharges into the old stream-bed.
Water was first impounded in the reservoir in September 1915, 86 million gallons being pumped from it in that year, whilst,
Q 75
Ashlar masonry of inner face and of overflow section of outer face, Rubble masonry of outer face, except
overflow section,
Ashlar masonry in string courses, cor- belling courses, parapets, culverts, valve-house, etc.,
P.W.E. Hongkong.
164,858 cub. ft.
59,400
$3,361
""
The valve-tower contains two wells, each 12′0′′ × 8′0′′, which connect at the base of the dam with two culverts, nearly circular in section, their diameter being 12 feet and their height 10 feet. Each well contains a stand-pipe, 18" diameter, from which draw- off pipes (15" diameter) connect with the reservoir. The draw-off pipes are at intervals varying from 10 to 15 feet, connected alternately with each stand-pipe. The stand-pipes are connected with 18" supply-pipes leading to the pumping station. At the outer end of the culverts is the outlet block containing a system of valves which enable either stand-pipe to be connected with either supply-pipe. Valves for controlling the draw-off pipes are con- tained within the valve-wells and external penstocks are provided for cutting off the water in the event of damage to any valve or pipe. Below each culvert, there is a wash-out pipe 21 inches in diameter, the valves for which are also contained in the valve- wells. By means of a connection with one of the wash-out pipes, provision is made for drawing off the water in the reservoir to a depth of 10 feet below the lowest draw-off pipe thereby increasing the effective impound by 38 million gallons. The valve-wells and culverts are faced throughout with granite ashlar. A valve-house, 31′0′′ x 10'0" internally, containing the valve-operating gear, sur- mounts the valve-wells. The house is built entirely of granite ashlar and is roofed with reinforced concrete. The floor of the valve-house and the platforms in the valve-wells, with the exception of those supporting the head-stocks, which are of cast-iron, are of reinforced concrete, made in removable slabs.
X
The roadway over the dam has a clear width of 16'6" between the parapets, which are of ashlar masonry in bays of alternate rock-faced and rough-punched stones, surmounted by a rock-faced ashlar coping. It forms part of the main road encircling the greater part of the Island of Hongkong, which is now being adapted for motor traffic. The overflow crest of the dam is 240 feet in length, the roadway being carried over it on 12 arches each of 20 feet span. The arches are of reinforced concrete faced with ashlar masonry and are supported on piers of ashlar masonry, the stones of which are bonded together with steel rods.
At the base of the dam, there is a water-cushion extending for a length of 153 feet, into which the overflow water is conducted by flood-water channels. The water-cushion discharges into the old stream-bed.
Water was first impounded in the reservoir in September 1915, 86 million gallons being pumped from it in that year, whilst,
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