Maintenance
All sewers deteriorate with age, but infiltration/inflow is a problem unique to sanitary sewers, since both combined sewers and storm drains are sized to carry these contributions. Holding infiltration to acceptable levels requires a higher standard of maintenance than necessary for structural integrity considerations of combined sewers. A comprehensive construction inspection program is required to prevent inappropriate connection of cellar, yard, and roof drains to sanitary sewers. The probability of inappropriate connections is higher where combined sewers and sanitary sewers are found in close proximity, because construction personnel may not recognize the difference. Many older cities still use combined sewers while adjacent suburbs were built with separate sanitary sewers.
For decades, when sanitary sewer pipes got cracks or other damage, the only choice was the expensive operation of digging up the damaged pipe and replacing it, usually requiring the street to be repaved afterwards. In the mid-1950s a unit was invented where two units at each end with a special cement mixture in between was pulled from one manhole cover to the next, coating the pipe with the cement under high pressure which then dried at a fast rate, sealing all cracks and breaks in the pipe.
Read more about this topic: Sanitary Sewer
Famous quotes containing the word maintenance:
“... in the fierce competition of modern society the only class left in the country possessing leisure is that of women supported in easy circumstances by husband or father, and it is to this class we must look for the maintenance of cultivated and refined tastes, for that value and pursuit of knowledge and of art for their own sakes which can alone save society from degenerating into a huge machine for making money, and gratifying the love of sensual luxury.”
—Mrs. H. O. Ward (18241899)
“In public buildings set aside for the care and maintenance of the goods of the middle ages, a staff of civil service art attendants praise all the dead, irrelevant scribblings and scrawlings that, at best, have only historical interest for idiots and layabouts.”
—George Grosz (18931959)
“War is in truth a disease in which the juices that serve health and maintenance are used for the sole purpose of nourishing something foreign, something at odds with nature.”
—Johann Wolfgang Von Goethe (17491832)