Case Study: Wastewater Treatment Plant Seal Pipe Flange Against Tree Root Ingress

SylWrap HD is used to prevent tree root ingress into a pipe at a wastewater treatment plant

Putting down roots – preventing tree roots penetrating an important pipeline in the process of wastewater treatment

When a tree penetrated an underground 1800mm pipe between flange plates connecting to a chlorine contact tank, a wastewater treatment plant needed to seal the line and protect it against future root ingress.

Case Study Data

Wastewater treatment plant
South East England
Repair Type
Flange repair and reinforcement
Tree root ingress between flange plates on 18000mm underground pipe

Products Used

Wrap & Seal Pipe Burst Tape
Self-amalgamating silicone repair tape which fuses to form a solid rubber band for the sealing of live leaks

SylWrap HD Pipe Repair Bandage
Composite repair wrap with a water activated resin which sets in minutes to form a rock hard protective shell

Case Study PDF

Case Study Details

The 1800mm underground steel pipe brought wastewater to the chlorine contact tank for the final stage of the treatment process. Known as tertiary treatment, it involves introducing chlorine to remove harmful pathogens which can cause diseases including cholera, polio, and typhoid.

After a significant reduction in performance was noticed, the ground around the pipe was excavated to identify the problem. It was discovered that a tree root had penetrated between two flange plates. This had caused a blockage of the pipe and potential recontamination of water which had undergone the majority of the wastewater treatment process.

A small amount of water was seeping through the gap caused by the tree ingress. Once the root was removed from the pipe, the plant needed a method to seal the leak and protect the flange against ingress occurring again.

The water company operating the plant sought technical advice from Sylmasta. Because the flange was 100mm thick, there was enough surface area for it to be repaired and reinforced using the normal SylWrap method for a live leak repair.

Wrap & Seal Pipe Burst Tape was wrapped over the point where the two flange plates connected. Wrap & Seal is a self-amalgamating silicone repair tape which stretches by 300 percent, fusing to form a solid rubber band over leak areas.

Several Wrap & Seal Tapes were applied on top of each other, bonding together to build pressure resistance. The application of Tapes continued until no more water was seeping from the pipe. Once the flange had been successfully sealed, attention turned to preventing future tree root ingress of the pipe.

The flange was next wrapped in SylWrap HD Pipe Repair Bandage. SylWrap HD is a composite wrap with a water-activated resin. It sets in minutes, curing to form an impact resistant sleeve around pipes and structures.

A SYL412HD Bandage was used as its 100mm width meant it fitted perfectly over the flange plates. With SylWrap HD providing a rock hard shell around the flange, future tree roots growing in the direction of the pipe once it was reburied would be unable to penetrate the weak spot between the plates.

Wrapping the flange with both Wrap & Seal and SylWrap HD took less than an hour. The water company were delighted with the speed of the application and the lack of disruption carrying out the repair caused.

The plant remained fully operational throughout the repair, compared to the significant downtime it would have faced in isolating both the pipe and the chlorine contact tank had the flange needed replacing.

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