Definition - What does Aerial Sewer mean?
An aerial sewer can be defined as a trenchless sewer pipe that is not installed sub-surface, rather passes over certain geographical features such as ravines, streams or other such areas where excavation is not possible, or where the area that the sewer pipe is supposed to pass through is too low lying. In such cases, the pipe is supported on piers or pedestals to give it the required grade.
Where no other alternatives are available, aerial sewers are used.
Trenchlesspedia explains Aerial Sewer
Pipes used for aerial sewers should be supported at all joints and should be designed to prevent settlement, frost heave and overturning. Ductile iron pipes with mechanical joints are recommended for installing aerial sewers. Between aerial and subsurface sewers, expansion joints are provided, and where subsurface sewers convert to aerial sewers, frost heaving should be minimized by using special construction techniques. Where aerial sewers will cross streams and rivers, the impact of debris and flood water should be considered.
During the construction of an aerial sewer, the pipe bottom is placed above the elevation of the 50-year flood stage. At the points where the aerial sewer pipe exits and enters, the soil should be protected against erosion.