Inspection chambers are used in drainage to provide access for clearing blocks, inspecting (it’s in the name) and testing the pipework system.
In the picture is a small inspection chamber installed for a customer they had raw sewage coming up from a gully pot as the pipe from there was connected into the main waste pipe. Unfortunately the original chamber had been buried beneath a pond and this was highlighted by a block that the customer could not clear. The waste pipe ran internally through the living room and the customer wasn’t keen on a hole being made in the wall and the pipe and the block being jetted clear from that point with the potential of backflow going into the living space (understandable). They had another toilet they could use on another run for the time being so we agreed to install a chamber. A hole was excavated to about a 1 meter in depth and 1 meter wide the pipe cut and then the chamber installed and back filled with pea gravel, also the block cleared. With the chamber it will clear any blocks on the customers run of pipe and luckily the buried chamber is on a run of pipe connected to neighbours inspection chambers also so if that blocks then it can be cleared from a neighbours chamber.