Definition - What does Benching mean?
Benching in the context of trenchless technology can be defined as the infill concrete between the walls of a manhole and the pipes. Manhole benching precipitates the hydraulic flow through the manhole unit during drainage events and sanitary sewer flows. The two most common benching configurations are a half bench and a full bench.
Also referred to as a bench.
Trenchlesspedia explains Benching
The floor of a manhole into which the channel is set; the bench is raised so that it can drain to the channel. Benching in manholes is always installed at a pitch so that any waste water that spills outside the pipe will flow back into the channel. Usually a sand and cement mixture is used to make benching. In half bench, the horizontal bench extends from the semi circular channel to the interior of the manhole wall, while the lower half of the pipe shape extends through the manhole. A full bench has better hydraulics because it is formed using the full depth of the channel. Benching should have a smooth finish to prevent abrasive materials from getting trapped on the surface.