P.W.E. Hongkong.
Q 46
The Filter Beds, which are six in number, are of irregular shape as they follow the contour of the hillside. The coping level is 300 feet above Ordnance Datum, whilst the level of the floor, at the outlet, is 293.25 O.D. The beds have a total area of 39,557 square yards and can be supplied with water either from Pokfulam or the Taitam Valley Reservoirs, by means of the mains mentioned above.
A conduit, 3′ 0″ x 3′ 3″, which runs along the back of the beds, delivers the water through 8″ penstocks into the pre-filters, in which it rises and overflows into the Filter Beds proper. The pre-filters, which are 3′ 0″ wide by 3′ 0″ deep and contain a 4″ layer of pea gravel, laid on perforated vitrified tiles, supported by bricks, act in the nature of strainers.
The inverts of the filter beds consist of a layer of 6 to 1 cement concrete, 9″ thick, laid in slabs, 12′ 0″ square, the joints between the slabs being filled in with asphalte. The walls are also of 6 to 1 cement concrete finished with a granite ashlar coping.
The filtering medium consists of a layer of sand, 2′ 6″ thick, over a 4″ layer of pea gravel, laid on perforated tiles, supported by vitrified bricks.
The filtered water from the beds enters outlet wells and, after passing over V-notches for measuring purposes, is conveyed in cast-iron pipes to the Service Reservoir.
The Service Reservoir has a capacity of 532 million gallons and a maximum depth of 20 feet, being divided into two approximately equal parts by a reinforced concrete division wall. The top-water level is 286 feet above Ordnance Datum.
The floor of the Reservoir, which is composed of 6 to 1 cement concrete, 12″ thick, has been laid in slabs 12′ 0″ square, with asphalte joints, the whole sloping to sumps at 265 Ordnance Datum. The enclosing walls, which are of gravity section, are composed of 8 to 1 cement concrete, with a 3″ layer of cement mortar on the inside face, and the division wall is composed of reinforced concrete. The roof consists of concrete jack arches springing from reinforced concrete beams, 6′ 0″ apart, centre to centre. These reinforced concrete beams are supported on main beams, also of reinforced concrete, which are spaced 12 feet apart, centre to centre, the main beams being carried on reinforced concrete pillars 12 feet apart, centre to centre. The roof is covered with a 12-inch layer of earth and turfed over.
The draw-off pipes are led to an Outlet Well where the control valves are situated and from there cast-iron pipes, 12″ and 14″ diameter, run through a short outlet tunnel to the Pokfulam Road Pumping Station and the City respectively. The Reservoir now feeds the Western District of the City.
A description of the 12″ cast-iron main for conveying unfiltered water from the Bowen Road Conduit at Albany Filter Beds to the new filter beds was given in last year's Report.
P.W.E. Hongkong.
Q 46
The Filter Beds, which are six in number, are of irregular shape as they follow the contour of the hillside. The coping level is 300 feet above Ordnance Datum, whilst the level of the floor, at the outlet, is 293-25 O.D. The beds have a total area of 39,557 square yards and can be supplied with water either from Pokfulam or the Taitam Valley Reservoirs, by means of the mains mentioned above.
A conduit, 3′ 0" x 3' 3", which runs along the back of the beds, delivers the water through 8" penstocks into the pre-filters, in which it rises and overflows into the Filter Beds proper. The pre-filters which are 3' 0" wide by 3' 0" deep and contain a 4" layer of pea gravel, laid on perforated vitrified tiles, supported by bricks, act in the nature of strainers.
The inverts of the filter beds consist of a layer of 6 to 1 cement concrete, 9" thick, laid in slabs, 12′ 0′′ square, the joints between the slabs being filled in with asphalte. The walls are also of 6 to 1 cement concrete finished with a granite ashlar coping.
The filtering medium consists of a layer of sand, 2′ 6′′ thick, over a 4" layer of pea gravel, laid on perforated tiles, supported by vitrified bricks.
The filtered water from the beds enters outlet wells and, after passing over V-notches for measuring purposes, is conveyed in cast-iron pipes to the Service Reservoir.
The Service Reservoir has a capacity of 532 million gallons and a maximum depth of 20 feet, being divided into two approx- imately equal parts by a reinforced concrete division wall. The top-water level is 286 feet above Ordnance Datum.
The floor of the Reservoir, which is composed of 6 to 1 cement concrete, 12" thick, has been laid in slabs 12' 0" square, with asphalte joints, the whole sloping to sumps at 265 Ordnance Datum. The enclosing walls, which are of gravity section, are composed of 8 to 1 cement concrete, with a 3" layer of cement mortar on the inside face, and the division wall is composed of reinforced concrete. The roof consists of concrete jack arches springing from reinforced concrete beams, 6' 0" apart, centre to centre. These reinforced concrete beams are supported on main beams, also of reinforced concrete, which are spaced 12 feet apart, centre to centre, the main beams being carried on reinforced concrete pillars 12 feet apart, centre to centre. The roof is covered with a 12-inch layer of earth and turfed over.
The draw-off pipes are led to an Outlet Well where the control valves are situated and from there cast-iron pipes, 12" and 14" diame- ter, run through a short outlet tunnel to the Pokfulam Road Pumping Station and the City respectively. The Reservoir now feeds the Western District of the City.
A description of the 12" cast-iron main for conveying unfiltered water from the Bowen Road Conduit at Albany Filter Beds to the new filter beds was given in last year's Report.
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