The Truth About Domestic Drain Lining ! Dig- Less Technology ?

Trenchless Technology, NO-Dig Drain Repair are the typical banner headlines you will see on web sites and adverts and in some cases it is possible to repair a defective system without the need to excavate. If you have a straight run of root damaged pipe work between two manholes and there are no junctions or sharp bends than a full repair can be achieved without any digging. However in the majority of domestic drainage systems it is usually necessary to have some excavation works in conjunction with a drain lining repair due to the following reasons;

• If there are no manholes or inspection chambers access has to be made into the system for the lining system repair
• Unlike main line drainage systems domestic drainage systems tend to have numerous junctions and changes of direction over fairly short distances often prohibitive to a full liner repair.
• Many domestic systems defects can be associated with the branch lines particularly where subsidence has occurred on the property itself, these lines are usually unaccessible without an excavation
• If you have root ingress to the main line drainage then the chances are the branch lines will also require attention
• Though it pains me to say it some systems are just beyond a drain lining repair and an excavation is the only option.

As i have already mentioned there are techniques for cutting out holes in the liner where a junction enters a main line and techniques for relining the junctions themselves but these are seldom used on smaller diameter domestic systems, this is down to cost and the fact that in most cases it is as easy to undertake localised excavations than to buy or hire the expensive specialist equipment required.

When Does Drain Relining Work

Every site is different and the key to a successful Cipp Liner Repair is the initial investigation works therefore a detailed drain camera inspection is vital using a quality inspection system, from this point you can assess the cause of the problem and the Drain Lining Method best suited to that specific site. Special consideration should be given to foul drainage systems particularly on smaller diameter pipe work and there is generally more tolerance on storm water systems where snagging of solids will not be an issue. 

When a system has failed due to tree root ingress in the joints but the joints themselves have not become misaligned then Cipp Drain Lining is an ideal repair, the roots can be removed from the system restoring the pipe work to its original internal bore and a liner can be installed. The liner will cover the problematic joints in affect creating one long joint free pipe so that the tree roots can not re-enter the pipe work. If the system has circumferential fractures or the joints are open and leaking but there has been no major movement to the host pipe Drain Lining will seal the system and prevent any further movement or water loss

If your foul drainage system blocks due to displaced joints you have to remember that the liner moulds itself to the host pipe so after the liner has been installed you will still see the displacement to some degree, typically the smoother finish of a well installed liner will compensate for the misalignment and the waste and water will continue to push through past the joint, In these cases you have to take into account the pipe size, the length of the system and the amount of fall on the run.

There does come a point on foul drainage systems where the joints become too displaced to be repaired with a Cipp Liner because the misalignment of the joint creates wrinkles in the liner itself, the liner along with the displacement reduces the internal bore of the pipe by too great a degree to get a satisfactory repair. There is obviously more tolerance on a 150mm pipe than a 100mm pipe and if it is one or two specific joints that are causing a problem than Drain Patch Repairs could be the answer as they do to some degree iron out the step in the joint.

We have in the past relined dipped pipe work with good results as the liner sealed the pipe work preventing any further settlement and the smooth finish of the liner helped any waste and water to push through the renewed section, prior to the repair being carried out the foul drain would block on a regular basis due to water loss and solids settling in the dip, but again the pipe size and volume of water passing through the system has to be considered.