Client
Affinity Water Limited
Value
£820,000
Sectors & Services
Water Industry Concrete Repair Condition Surveys Coatings Membranes Cleaning & Preparation ECI (Early Contractor Involvement)
Iver Water Treatment Works, located in Buckinghamshire, was originally constructed in 1974 with a treatment capacity of 160 Ml/d and allowance for future expansion. Through successive upgrades, the works now supplies up to 225 Ml/d, making it a critical asset within Affinity Water’s operational network.
As part of the framework contract, CRL was appointed to undertake a major refurbishment of the pulsator clarifiers and flash mixers, assets that are fundamental to the treatment process. Age-related deterioration to structural concrete, steelwork, handrails and covers, combined with operational and safety constraints, necessitated a carefully planned refurbishment to maintain reliability, safety and long-term asset performance while keeping the works operational.
Services undertaken
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Early Contractor Involvement investigations for clarifier cover solutions
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Removal of asbestos pipework and toblerone baffles and plates
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Installation of GRP ladders within clarifiers
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Concrete repairs to flash mixer structures
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Replacement of handrails in flash mixer areas
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Cleaning and coating of existing handrails in clarifiers
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Removal of sludge from tanks
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Overbanding of defective joints
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Waterproofing repairs to rooflights and walkways
CRL’s scope extended well beyond conventional refurbishment, demonstrating a diverse range of technical expertise across structural repairs UK and water-sector asset management. The works were delivered within tightly controlled outage periods, limited to two six-week windows with access to only ten clarifiers at any one time. This required detailed programming, close liaison with Affinity Water, and meticulous sequencing to minimise disruption to live treatment operations.
The refurbishment included the removal of legacy asbestos pipework and toblerone baffles and plates from each clarifier, undertaken using a specialist licensed asbestos contractor under CRL’s Principal Contractor duties. Safety management was further complicated by the presence of ozone gas, which was mitigated through the use of dedicated gas monitoring and robust permit systems. Structural concrete repairs were carried out in the flash mixer areas where deterioration had occurred, ensuring reinstated surfaces met both durability and hygiene requirements.
Access and operability improvements were delivered through the installation of twenty GRP ladders, each approximately 4 m long, providing corrosion-resistant and low-maintenance solutions suited to the aggressive treatment environment. Existing handrails within the flash mixers were replaced, while other handrails throughout the clarifiers were cleaned and coated to extend their service life. Sludge was removed from the tanks to allow inspections and repairs to be completed safely and effectively. Defective joints were overbanded to restore watertightness, and localised waterproofing repairs were undertaken to rooflights and walkways.
In parallel, CRL undertook Early Contractor Involvement works to address the degradation of existing clarifier covers. This involved detailed investigations, collaboration with structural engineers and specialist cover manufacturers, and site visits across the UK, USA and Canada to review alternative systems. This proactive approach allowed CRL to present Affinity Water with a well-informed, value-driven solution based on proven performance in comparable environments.
"This project was typical of the type of responsibility we were asked to take on by Affinity Water as part of the Framework. There was a lot of collaboration and ECI works involved to come up with the final solution."
Michael Balletta | Infrastructure Manager | CRL
The refurbishment at Iver WTW focused on restoring and enhancing long-term durability rather than short-term fixes. Concrete repairs addressed underlying defects to prevent further deterioration, while overbanding of joints improved watertightness and reduced the risk of leakage and contamination. The cleaning and coating of handrails provided ongoing corrosion protection in a highly aggressive process environment, reducing future maintenance demands.
By integrating ECI investigations into the project, CRL supported informed decision-making on cover replacement strategies, helping to mitigate long-term operational and structural risks. The use of durable GRP access systems, targeted waterproofing repairs and robust safety controls collectively enhanced resilience, asset performance and compliance. CRL’s ability to manage complex safety, operational and technical constraints while delivering high-quality concrete repairs and refurbishment works reinforces its reputation as a trusted partner in water-sector asset management.
