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The dam was completed in May and the contingent works in August, 1931. The Reservoir filled for the first time during the summer, and overflowed on August 11th, 1931.
The Reservoir has a direct catchment area of 90 acres, a capacity of 185.5 million gallons, and an area of 15 acres at a top water level of 380.00 A.O.D.
Mechanical equipment was installed by the Contractors for the construction. Materials, except stone which was available at the site, were transported by road to an unloading station near the East end of the dam and were carried over the valley to the mixing station by an overhead cableway. Sand and cement were deposited directly by cableway into storage bins above a concrete mixer of one cubic yard capacity, whilst aggregate was delivered to a similar storage bin by bucket elevator.
The mixed concrete for deposition in the dam was hoisted inside a steel tower and discharged into a steel shute suspended from a cable across the valley.
The dam, which has a length of 347 feet at top water level, is of the gravity type constructed of mass cement concrete and is composed of 5 to 1 cement con- crete, faced on the upstream side above 285 A.O.D. with smooth faced concrete blocks and backed with displacer concrete varying from 6 to 1 to 8 to 1 according to elevation. The concrete backing is faced on the downstream side with concrete blocks representing rock faced ashlar masonry.
The height of the roadway over the dam, which is at an elevation of 387.00 A.O.D., is 143' 6" from deepest foundation level and 118′ 0′′ from stream bed level.
Four draw-offs, 18" in diameter and controlled by 18" Penstock and 15" Sluice Valves, are provided at levels of 300, 320, 340 and 360 A.O.D. They are connected to an 18" diameter standpipe accommodated in a valve well surmounted by a valve house from which the valves are operated.
An 18" diameter washout pipe controlled in a similar manner from the valve house has been provided at a level of 270 A.O.D.
An 18" diameter connection between the new standpipe and the supply main from Kowloon Dam to the Kowloon Filters is carried across the South-East flood water channel of the dam on a reinforced concrete skew arch bridge of 42′ 0′′ span.
The overflow, which consists of 16 openings 12′ 0′′ long by 3′ 6′′ deep, dis- charges into floodwater channels on either side of the stream, from which a water cushion, provided in the stream bed at the toe of the dam, collects the flood- water and discharges it into the old stream course.
The roadway over the dam is surfaced with fine cement concrete and is sur- mounted on both sides by a pilaster and balustrade parapet of cement concrete.
A diversion channel, having a length of 516 feet, an average width of 12′ 6′′ and a depth of 4′ 3′′, and stepped to suit the ground, collects the overflow or draw off from the Reception Reservoir and diverts it into the Byewash Reservoir. It is constructed of cement concrete, the invert being 9′′ thick. The side walls, which have a batter of 8 to 1, are of similar materials.
The Access Road is 10′ 0′′ wide throughout, the section from Taipo Road to the dam being 1,300 feet long and having a down grade of 1 in 11.63. Across the dam it is level and from there to Shek Lai Pui Filters it is on an average uphill grade of 1 in 9.34 for a length of 700 feet followed by an average down grade of 1 in 44.6 for a length of 535 feet.
The road has been constructed partly in cutting and partly on embankments and retaining walls. It is surfaced with tar macadam on a foundation of lime and cement concrete and is channelled where necessary.
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