Huge New Reservoir Completed in London
Description of the “Queen Mary” Reservoir Which Will Add Greatly to the ater Supply—American Type Pumps Used
THE following account will be of especial interest as describing what is the largest reservoir in Great Britain and probably the most extensive of its kind in the world. The fact that the pumps supplying the reservoir water to the city of London are of American make will also be of especial interest.
The fresh water supply of London, England, will be greatly increased by the recent completion of the Littleton reservoir, renamed “Queen Mary’s Reservoir,” located three-quarters of a mile north of the Thames River between Staines and Shepperton, the center of the huge reservoir being about two and one-half miles southeast of Staines.
Dimensions and Capacity of Reservoir
The construction of the reservoir was a colossal engineering task and was made imperative because of the great growth of the city of London. It embodies the most modern engineering devices. The dimensions of the reservoir are 72,3 acres, it has a depth of 38 feet, and a capacity of approximately 6,750,000,000 gallons, enough to supply every man, woman and child in the world with their daily rations of fresh drinking water and with a large supply left over for domestic purposes.
The giant project was undertaken by the Metropolitan Water Board of London, under the direction of the Board’s Chief Engineer, Henry E. Stilgoe, M. Inst. C. E., and his assistants, who are much complimented upon the success of the vast undertaking.
Method of Construction
The reservoir, which is an irregular seven-sided polygon with rounded corners, virtually constitutes a vast clay wash basin, a mile and one-quarter across. The embankments are composed of earth with a clay puddle core carried down and keyed into the London clay which underlies the whole region. The puddle core extending, as it does, down through the center of the surrounding embankments, may be compared to the sides of the wash basin preventing the escape of the water. The bottom of the giant basin has been excavated six feet, also into the London clay which prevents seepage through the bottom.
Pumps of American Type
The water is drawn from the Thames River near the Penton Hook lock, which will be familiar to all who have gone up the Thames in a tow boat. It is a very picturesque section. The intake is beneath the three arches of a large concrete bridge faced with granite which is built with the tow path across the top so as not to interrupt towing. Thence the water proceeds through an open channel for three-quarters of a mile to the steam power pumping station which pumps the water through steel pipes over the embankments and into the reservoir. Four Worthington-Simpson horizontal steam-driven centrifugal pumps with a combined capacity ranging from 343,000,000 gallons per twenty-four hours against a head of thirty feet, to 250,000,000 gallons against a head of forty-six feet, the revolutions at these heads being 125 and 140 per minute, respectively. The engines are of the Worthington Uniflow type, each of 770 horsepower, single cylinder, a combination of American and English ingenuity. The most modern devices are used in carrying and handling coal to the boiler furnaces.
Site Selected in 1911
The site of the Queen Mary Reservoir was selected by the Metropolitan Water Board of London in 1911 with
reference to the suitability of its location to the Thames River, and the water works of the board which are smaller than the giant plant just completed. Work was commenced in 1914 but went along very slowly, because of the war, until 1916, when it was completely suspended by the order of the Ministry of Munitions. Construction remained in abeyance until 1919, when a contract was made with S. Pearson, Ltd. Incidentally all bids had to conform to the closest specifications for the observance of economy and efficiency in performance.
Supplies Both North and South of London
The water of this reservoir is used to supplement supplies for both the North and South of London. Part of the supply is discharged through reinforced concrete aqueducts into the Staines aqueduct which passes close to the North side of the Queen Mary reservoir. The remainder is conducted by aqueducts to Kempton Park where the Metropolitan Water Board has reservoirs and filters.
The main embankments of the Queen Mary reservoir rise about 38 feet above the surrounding country. When the reservoir is completely filled to a depth of 38 feet, the normal water level is about six feet below the top of the embankment, for, as already explained, the whole site was excavated about six feet, through the top soil and into the London clay. The sides of the embankment slope to a 3 to 1 slope on the water face and a to 1 slope on the outside. The outside face of the reservoir has been covered with rich soil and loam and will be attractively landscaped with ornamental shrubs. The lower part of the water face of the embankment is protected by six-inch concrete slabs arranged to. resist the hack wash of waves.