Case Studies

No-Dig Repair Rebuilds Collapse Under House Extension

Last month, on behalf of Severn Trent Water, Colus were asked to fix a drainage and sewer system problem at a property in Leicester.

Using their expert knowledge, Colus identified that there had been a total collapse beneath a house extension.

Severn Trent Water were initially planning on demolising and re-building the extension. However, after consulting Colus on the most suitable and cost effective method of repair, it was decided that the reapir could be carried out using ‘No Dig’ techniques’ from the manhole access saving significant costs to Severn Trent Water and disruption to the Homeowners.

Though the Colus team were aware that this was quite a difficult method, they used their innovative skills to repair the pipes.

Colus used rods, jetting and a robotic cutter to create a path to allow the team access to the collapsed drain and begin the repairing process. A triple layer patch was then positioned in the void, wrapped around a packer and inflated to 2.5 bar.

Colus performed CCTV drain surveys to determine where the incoming disconnected lateral was, and in this case they used two CCTV units to find the position for the new branch which was then reconnected.

The branch had a diameter change to 150mm which would have made the repair very difficult so the pipe was downsized to 100mm using reinforced patches and inserted into the main line.

The intruding patch was then cut back before a double skin patch was placed over the junction and reopened to 100mm diameter.

The work was completed when a 4.5mm superflex liner was inserted into main line. A final double skin patch was positioned over the incoming lateral from branch line.

Finally the lateral was reopened and the repair was complete. The repair is water tight and of a high strength and the new main line pipe wall is approx 9mm thick and the incoming later is approx 6mm thick.

The repair took 3 days in total using 2 teams because of the access issues saving Severn Trent Water an estimated £5,000.

Colus are an innovative sewer rehabitilation service provider. For more information on their services please call 01934 838262.

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