Adler and Allan add 10 years to a critical asset and save £7.8 million in 24 hour turnaround digestor project

Delivering wastewater safely back to the environment is a complex operation. Done correctly, it returns clean, treated water to rivers and converts methane by-products into sustainable energy. When assets fail, however, the process presents serious pollution hazards.

When surface cracks appeared on the roof of a sludge digester at their sewage treatment works, the client needed an environmentally sound solution that didn’t require days of downtime. If left untreated, the damaged sludge tank could potentially release harmful, highly combustible methane gas. Replacing the digester would cost in the region of £8 million and cause prolonged disruption to the treatment plant’s round-the-clock operations.

A comprehensive asset inspection was undertaken to evaluate general structural integrity, the health of the digester’s surrounding components, and working conditions for onsite crews. Experienced consultants provided specialist guidance on methane containment and pollution risk reduction and a targeted three-week plan was created to prepare the site, repair, and future-proof the asset, and limit disruption to one day.

Adler and Allan’s team worked with subcontractors and staff to establish a safe working environment. This involved scaffolding provision to access the site, which sat within a controlled area, and bypass pipework installation to minimise pressure in the digester during preparation and treatment.

Tailored repair plans for the roof and surrounds featured AdlerCoat™, a high-tensile, high-elongation, high-build, and fast-set elastomer. Its fast-setting formula makes the product an ideal solution to quickly treat damage to the plant’s key asset, while minimising costs and operational downtime.

Once safe access had been established, refurbishment took a four-step approach – with environmental risks and service continuity managed at every stage.

The digester’s roof and surrounds were shotblasted to remove contaminants and prepare surfaces for coating. Cracks and visible defects were repaired using conventional civils techniques. Stainguard primer was applied to maximise adhesion and existing assets were primed with a Rallithane jointing compound. Qualified engineers then coated the roof and surrounds with Adler and Allan’s specialist polyurea AdlerCoat™ lining. The fast-drying elastomer is specifically formulated to build a tough, long-lasting surface bond, creating a flexible and resilient monolithic membrane with water and chemical resistance. After being coated, all surfaces were validated using a dielectric testing method to provide a 100% warrantied containment solution.

This cutting-edge lining treatment extended the digester’s life by a minimum of 10 years – at a fraction of the cost of replacement – and ensured continuity and compliance for the client.

The project achieved the following savings:

  • £7.8m Savings achieved by Adler and Allan’s refurbishment programme
  • £200,000 Adler and Allan project costs
  • £8m Cost to replace damaged sludge digester

Added benefits:

  • Reduced insurance premiums
  • Expert protection against pollution and environmental harm
  • Asset life extended by 10 years
  • Full operations resumed within 24 hours
  • 100% compliant and warrantied solution

Ongoing cooperation and liaison throughout the three-week project period ensured that all deliverables were met safely, efficiently, and on time. The client breathed new life into a critical asset while saving millions on replacement, compliance breaches, and future environmental fines



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