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:
“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 (1749–1832)
“My course is a firm assertion and maintenance of the rights of the colored people of the South according to the Thirteenth, Fourteenth, and Fifteenth Amendments, coupled with a readiness to recognize all Southern people, without regard to past political conduct, who will now go with me heartily and in good faith in support of these principles.”
—Rutherford Birchard Hayes (1822–1893)
“However patriarchal the world, at home the child knows that his mother is the source of all power. The hand that rocks the cradle rules his world. . . . The son never forgets that he owes his life to his mother, not just the creation of it but the maintenance of it, and that he owes her a debt he cannot conceivably repay, but which she may call in at any time.”
—Frank Pittman (20th century)