Leach Field

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Leach Field


(also filtration field), a plot of land on which sewage liquid undergoes natural biological decontamination as it is filtered through soil horizons.

Leach fields are established on sandy, sandy loam, and loamy soils with good filtration properties. They are flat and have an area of 0.5–2 hectares (ha). There are dividing ridges measuring 0.8–1 m high. Sewage liquid from which solid waste, fat, and worm eggs have been removed is fed past gates and through open canals onto the field in a layer of 20–30 cm (in the winter it is frozen to 75 cm). The sewage percolates through the soil and runs through drains to a collector. It then is dumped into a river. After the sewage liquid has been absorbed, the surface of the field is tilled and then flooded again.

Permissible daily norms for loads on leach fields are 70–125 cu m/ha for sand, 50–100 cu m/ha for sandy loam, and 40–70 cu m/ha for loam. Leach fields in which the waste is fed into the soil through drains are set up to decontaminate small amounts of sewage. In contrast to sewage farms, leach fields are not used for crop cultivation.


References in classic literature ?
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All men can see the tactics whereby I conquer, but what none can see is the strategy out of which victory is evolved.
Then the Pygmy army would march homeward in triumph, attributing the victory entirely to their own valor, and to the warlike skill and strategy of whomsoever happened to be captain general; and for a tedious while afterwards, nothing would be heard of but grand processions, and public banquets, a nd brilliant illuminations, and shows of wax-work, with likenesses of the distinguished officers, as small as life.
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Now, Tom Thurston was as skilled in a fortune-hunter's wiles as Napoleon was in military strategy.
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With a rapid sense of strategy he sometimes showed, Fisher sprang from the bank and raced round the lake to the head of the little pier of stones.