Level Invert Connection

Level Invert

In drainage the typical manhole connection is level soffit or stepped connection. That is the invert level of the main run is relatively lower than the incoming laterals.

This point is practically important to note because when your design has some degree of gradient or fall restriction then 50mm can make a difference.

For example if you are connecting a 100 diameter into a 150 diameter main run pipe then your computed invert level taken from the origin of the 100 diameter pipe should be 50mm lower. If you fail to add this additional 50mm into your design and if the invert level of the connection point does not have enough depth then this can be an issue in actual construction.