Re-rounding Pitch Fibre Drains
What are pitch fibre drains?
Pitch fibre was commonly used in construction work during the 1960’s and 1970’s. Due to the age of the pitch fibre used most drains of this type have reached the end of its useful lifespan by now. We tend to encounter pitch fibre drains whilst using our CCTV camera's after a blockage or with a CCTV drain survey to check for issues. Commonly the pitch fibre drainage we encounter has squashed and bubbled preventing a clear flow of solids. Sometimes the impact of the crushing and blistering is so severe that we cannot get the drain camera to run through the pipework. If this is the case the frain would be approximately 50% squashed and delaminated.
How do we repair pitch fibre drains?
Depending on the severity of the damage to the pipe, in some circumstances we can re-round the old squashed and bubbled pitch fibre by using our re-rounding equipment which saves digging out the pipe. Obviously the earlier we carry out this work before the pitch fibre drains become too bubbled or squashed. Re-rounding will only be successful until a certain point where the pipe reaches a level of disrepair.
With early intervention we can use our specialist re-rounding equipment to force the pipe out to an 'open' position removing any bubbles present. Using various grades of the heavy winched re-rounder we aim to bring the pipe back to approximately 95% of its original circular diameter. A further process is carried out to clean the pitch fibre wall of any small lumps or debris that could cause further blockages. Once we are happy with the condition of the drain we then install the liner to strengthen the pitch fibre pipework. This process is a no-dig operation and can be done via existing manholes.
Obviously if the pitch fibre has degraded beyhond repair then the pipe will not be able to be re-rounded and lined. We may be able to replace section but this will require excavation in conjunction with any re-rounding that is possible.
How long will the repair last?
The lining material we use exceeds WRc criteria and provides a 50yr design life coupled with a safety factor of 2. This gives a 100yr life expectancy once the pipe has been re-rounded and lined meaning you won't have to worry about your drains again.