Engineering Wonders of the World
Volume III

HOW LONDON GETS ITS WATER. 201 will deliver 11,000,000 gallons of the Ching- ford water daily, when occasion requires, into the New River channel at Stoke Newington. It may be remarked in passing that this tur- bine is as notable for its small size as the Cornish engines at Lee Bridge are impressive by virtue of their great dimensions. A cas- ing 4 feet in diameter, and but a foot or so long, houses a wheel which, rotating 7,500 times a minute, develops even more power of the Thames by mains passing under the river. The reservoir has a length of 824 feet, a greatest width of 587 feet, a water area of about 10 acres, a general depth of 21 feet 6 inches, and a greatest depth of 34 feet. The first operation to be carried out was to excavate 173,000 cubic yards of earth and clay, which supplied the material for 19,000,000 bricks. On the north and on portions of the THE SUPPLY CHANNEL OF THE CHINGFORD NEW RESERVOIR. than the “ Prince ” or the “ Princess ” de- scribed on a later page. This high-speed tur- bine, and the centrifugal pump which it drives, represent one of the latest developments in pumping machinery. The Beachcroft reservoir at Honor Oak, opened on May 5, 1909, is remarkable as being the largest covered reservoir in the world constructed at one time and under one contract. The main object of the reservoir is to , supply water at low pressure to the south-eastern part of the Metropolitan Water Board’s area. The water can, if ne- cessary, be transferred to the northern side The Beachcroft Reservoir. east and west sides, where the top of the reser- voir is above the natural surface of the ground, embankments were built of alternate horizontal layers of earth and burnt ballast. Between the outside retaining walls and the ground a 3-foot wall of puddled clay was carried down to and into the London clay to form a water- tight enclosure independently of the brickwork. The whole of the bottom is covered by in- verted arches of concrete crossing one another at right angles. At the points of intersection, 21i feet apart in both direc- . . . 5 . , . p . The Roof. tions, rise brick piers oi cruci- form section, connected by arches running the whole length of the reservoir from east to