SEWAGE AND HOUSE DRAINS.

Globe, Volume XXI, Issue 1827, 30 December 1879, Page 3

SEWAGE AND HOUSE DRAINS.

To sewer a town, and then l»we house drains to haphazard construction, is simply little better than to waste the ratepayers' money. Comfort and means for health are only to be secured by the best house drainage, and the best house drainage will not be accomplished by builders working no responsibility. The sewage of a town or village will consist of waste water and excreta from the houses, and the volume, in round figures, may range from 100 to 250 gallons per day from each house. This r lume will probably S.ovr off in about eight hours, so that the sewers must provide for not less than three times this volume, if every drop of roof and surface water can be excluded. As this cannot in all cases be accomplished, the sewers should provide for not less than 1000 gallons from each house, or, for a town of 1000 houses (5500 population), have a delivering capacity of about 1,000,000 gallons. An outlet sewer of two feet diameter, laid with a fall of five feet per mile, will deliver upward of 2.000,000 gallons, flowing a little more than half full; and, as provision should be made for an increase of population, a sewer of two feet diameter may be provided for each 5,500 persons, where no better fall than one in one thousand can be obtained. Lesser diameters will answer where there are no greater falls. Towns situated on land rising considerably will best be sewered in zones ; that is, by intercepting lines of sewers contouring the site, aB such sewers will prevent gorging the low-level districts, and also prevent the rush of sewage down steep gradients at high velocities, which, in times of heavy rain, may burst the low-level sewers at the steep gradient junctions. Sewers with steep gradients, if the flow of sewage is unbroken, get up a velocity in the sewage, which is liable to be very injurious in its wearing action on the sewers. Sewage should not be allowed (except when flushing is in operation) to acquire a greater velocity at any state or time of more than six feet per second, as any higher velocity will take grit or other solids along the sewer invert with a cutting and disintegrating action rapidly destructive to the material of the sewer.