- Material
- Concrete, mortar or cementitious ingress
- Check first
- State and extent of the obstruction, plus pipe condition
- Method limit
- More pressure does not guarantee complete or damage-free removal
- Verification
- Inspection of the exposed pipe and connections
Understanding the obstruction
Fresh cement washings, loose construction debris and hardened concrete are different problems. The timing of the ingress, the work under way at the time and any available product information help establish what is likely to be in the drain.
A survey can show the accessible extent of the blockage and the condition of the visible pipe. If the camera cannot pass the leading edge, the amount and condition of material beyond it remain unknown.
Removing concrete without damaging the drain
The method has to remove unwanted concrete while leaving the pipe or chamber material intact. Clay, plastic, concrete and lined drainage all respond differently, and existing damage or previous repairs can make aggressive cleaning more likely to cause harm.
Water jetting or mechanical removal may be suitable once the obstruction and pipe have been assessed. If the drain is badly damaged or cannot be reached safely from within, repair or excavation may be the more appropriate option.
Recovering debris and washwater
Concrete fragments should not simply be driven into the next section of drainage. Cement-contaminated washwater also needs a controlled route because contaminated water must not be allowed to enter surface-water drainage or a watercourse.
The method should be reviewed as the pipe is exposed. If the underlying condition is worse than the survey suggested, the cleaning limit may need to change to avoid further damage.
Inspection after removal
The final inspection should record what has been cleared, any obstruction that remains and the condition of the exposed pipe and connections. Cleaning may reveal defects that need repair, so internal removal is not a substitute for excavation in every case.