Definition - What does Invert level mean?
An invert level of a sewer pipe simply means the level of the inside bottom of the pipe or the lowest point on the inside of the pipe. The invert level of a drain pipe is never at the same level and has a minimum slope of 1/8th inch per foot. Depending on the thickness of the pipe, the ground below the pipe may be slightly lower than the invert level of the pipe.
Adequate slope is necessary to facilitate the flow of sewer by gravity as most sewers are gravity sewers. Sometimes scouring and deposition of solid particles can damage the pipe.
Such pipes can be replaced using trenchless rehabilitation techniques such as sliplining, pipe bursting or can be lined using cured-in-place pipe (CIPP).
Trenchlesspedia explains Invert level
The reference for an invert level is usually a floor slab above it. Knowing the elevation of the floor slab and the ceiling height, the Invert level can be measured. Knowing invert level also helps to determine the location of a drop manhole if required. When two sewers connect and the level difference between invert of branch sewer and water line in main sewer at maximum discharge is more than 0.6 meter, a drop manhole is constructed.
It can have a vertical or near vertical drop pipe from the sewer at higher elevation to the one at lower elevation.