The New Student's Reference Work/Sewerage

Sew′erage, a system of underground pipes or conduits for the removal of sewage or the rain-water of a place. Sewerage is required for sanitary reasons in towns and cities. In the country, where population is not dense, sewage can be disposed of without any elaborate system, though care must always be taken that the water-supply is not contaminated. The construction of elaborate sewer-systems is found in ancient cities, as Babylon, Jerusalem and Rome, but it is only within recent years that it has received the attention it deserves in modern cities. There are two systems in use, — the combined and the separate system. In the combined system the same pipes carry both the sewage and the storm-water; in the separate system, called the Waring system, there are separate pipes for the sewage and for the storm-water. In the latter system the flushing is done by automatic flush-tanks supplied with water from the town waterworks. The separate system is recommended by most sanitary engineers. The liquid sewage may flow due to the fall of the pipes, but in many cases pumping has to be resorted to. Among the methods of sewerage disposal are the following: (a) by dilution by discharge into a large mass of flowing water which is not used for a water-supply, as at New York City and in towns on the lower Mississippi; (b) by running the liquid sewage over a large area of land and letting it oxidize in the air; and (c) by chemical treatment to kill the organic life. In some cases, as at Berlin, Germany, the sewage is used to fertilize land which is cultivated. Chicago has constructed a drainage canal at a cost of $53,000,000 to dispose of its sewage by dilution with a large body of water taken from Lake Michigan and emptied into Illinois River.