A capped pipe stub and flange in a decommissioned underground drainage system at a landfill site undergoes encapsulation to reinforce the initial capping, protect against corrosion and prevent the potentially damaging release of toxic leachate into the environment.

Case Study Overview

Site Landfill site
Location South Wales
Pipe Type Capped stub and flange
Repair Type Encapsulation
Products Liquid Metal Epoxy Coating, SylWrap Pipe Repair Bandage

Pipe Defect

Drainage is vital on landfill sites to prevent rainwater from pooling or flooding and mixing with toxic fluids. Rainwater which ends up dissolving environmentally harmful substances like chloride, nickel, ammonia and other forms of nitrogen is known as leachate.

Leachate must be collected and managed correctly. If it is allowed to escape into soil, groundwater or surface water, it can have an acute and chronic impact on the environment, causing serious pollution.

A series of underground pumps were found not to be working at the landfill site in South Wales. This gave rise to the possibility of leachate formulation and release.

In response, it was decided to decommission the existing drainage system and replace it with a new one. As part of the decommissioning process, every pipe at the start of the old network had to be capped.

To further reinforce after capping, the site wanted to encapsulate the main pipe stub and its flange plate to protect against corrosion. Such a measure would lessen the chance of future failure and the escape of toxic leachate.

SylWrap Solution

The pipe stub requiring encapsulation was protruding around 300mm from a concrete wall towards the bottom of a chamber. There was little room to move within the chamber and access was further restricted by various metal structures above the stub.

Sylmasta approved contractor Arch Services were appointed by the site to find a solution. After an inspection and consultation with Sylmasta technicians, a means of protecting the stub from corrosion was devised.

Several layers of Liquid Metal Epoxy Coating were applied via brush to the flange and stub plate. When cured, Liquid Metal formed a new metallic surface over the existing stub, protecting the original metalwork from corrosion and chemical attack by attacking as an external shield.

Whilst the final coating of Liquid Metal had gelled but remained tacky, the sub was then encapsulated with SylWrap Pipe Repair Bandage.

A SYL633HD Bandage was activated with water, wrapped around the stub and smothered over the plate. More water was applied to smooth the Bandage once it was in place. When cured, it provided a rock-hard, impact resistant covering.

Outcome

Using Liquid Metal and SylWrap Bandage in conjunction enhanced the sealing power of the repair, preventing any fluid left inside the system after decommissioning from escaping in future.

From the outside, the stub now had double the protection against external corrosion and the harmful substances which are part and parcel of the landfill process.

Follow Up

Speaking after the application, Arch said: “Given the protruding bolts and cramped application position, this was not a ‘pretty’ repair. But it absolutely did the job. The site now has full confidence that the capped pipe will not fail in future.”

Products Used

Liquid Metal
Epoxy coating brush applied to create an external shield against corrosion

SylWrap Pipe Repair Bandage
Water-activated wrap used to encompass pipes with a rock-hard, impact resistant layer

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