Loosen material and recover it
Jetting can move sediment towards a suitable collection point, while suction recovers material from the network. The equipment arrangement depends on the pipe size, sediment consistency, available chambers and the condition of the pipe.
The intended result is removal of the deposit, rather than simply moving it to another restriction downstream. The recovery point and the extent of each working section therefore matter. The quantity recovered is useful information, but it does not by itself prove that every part of the specified length is clear.
Free-liquid pumping can make access or observation easier while leaving a settled bed below. Where dense material remains, its location and the reason it could not be recovered should be distinguishable from areas that have been cleaned.
Account for flow and network operation
A sewer may continue receiving discharge from connected properties or site activities. The cleaning plan needs to account for those flows and the effect of working at the selected chambers. The time available and the accessibility of equipment can change during the work.
Ownership and operating responsibility need to be established for the affected section, particularly where a private site connects to a public network. Any access involving enclosed spaces has its own planning requirements; the HSE confined-space guidance provides the relevant framework.
