Client
MWH Treatment Ltd
Value
£267,500
Sectors & Services
Water Industry Concrete Repair Condition Surveys Membranes Cleaning & Preparation Projects
CRL was appointed by Severn Trent Water to undertake the survey, repair and waterproofing of a 2 million gallon clean water service reservoir at Mythe Water Treatment Works. The asset is a critical component of regional potable water infrastructure and required refurbishment to address ageing waterproofing systems, localised concrete defects and long-standing water ingress issues.
Delivered over a 14-week contract period, the works were time sensitive and technically demanding, particularly given the winter conditions and the need to maintain strict water industry standards. The project was essential to safeguard water quality, structural integrity and long-term operational reliability.
Services undertaken
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Condition survey of clean water service reservoir
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Installation of heat and moisture controlled protective marquee
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Removal of roof landscaping and failed waterproof membrane
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Formation and sealing of construction joints with polysulphide mastic
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Overbanding of joints using Fosroc Proofex flexible sheet banding
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Reprofiling and reconstruction of perimeter edge beam upstand
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Installation of Fosroc Proofex sheet waterproof membrane system
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Waterproofing of hatch access points with epoxy membrane system
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Joint sealing using Sika Combiflex waterproofing banding system
CRL delivered a carefully sequenced refurbishment programme combining structural repairs, specialist waterproofing and confined space working practices. Due to low ambient temperatures and programme constraints, the entire tank roof was enclosed within a heat and moisture controlled, air-conditioned marquee. This enabled consistent environmental conditions to be maintained, ensuring materials achieved their required performance characteristics and curing regimes.
The existing roof landscaping, including grass cover and a failed waterproof membrane, was removed using lightweight plant to comply with strict load restrictions. The exposed substrate was then thoroughly prepared using high-pressure water jetting at 7,000 psi to remove laitance, residual primer and surface contamination. Following preparation, localised concrete repairs were undertaken and all construction joints were carefully formed and filled with flexible polysulphide mastic. These joints were then overbanded using Fosroc Proofex flexible sheet banding to provide continuity of waterproofing across movement interfaces.
A known issue with standing water was addressed by carefully removing a section of the perimeter edge beam upstand along one elevation. The upstand was reinforced, tied down and reprofiled in concrete to introduce positive falls and promote natural water run-off, demonstrating CRL’s practical approach to resolving underlying defects rather than simply treating symptoms.
Once all repairs were complete, the entire roof surface and associated perimeter wall downstands were encapsulated with the Fosroc Proofex sheet waterproof membrane system. This was protected with Sheetdrain 80 cavity drainage and a geotextile protection layer prior to reinstatement with aggregate backfill. Hatch access points were treated separately using a Fosroc epoxy waterproof membrane with a UV-stable coloured finish.
Internally, CRL operated under confined space permits to survey floors, walls and columns, carrying out isolated concrete repairs using DWI-approved materials. Wall and floor joints were prepared and sealed using the Sika Combiflex waterproofing banding system. The project highlights CRL’s capability in delivering complex concrete repairs and waterproofing works within regulated water industry environments, supporting long-term asset management objectives.
" The use of a fully controlled, climate-managed marquee allowed waterproofing and concrete repairs to be completed to specification despite winter conditions. Through careful sequencing, specialist materials and strict confined space controls, the team successfully refurbished a critical clean water asset, ensuring long-term integrity and compliance while maintaining Severn Trent Water’s operational requirements.”
Project Manager | CRL
The completed works provide a robust, multi-layered waterproofing and repair solution designed to extend the service life of this critical clean water asset. The Fosroc Proofex membrane system, combined with flexible joint detailing and effective drainage, delivers long-term resistance to water ingress and accommodates structural movement. Reprofiling of the roof edge beam has eliminated standing water, reducing the risk of premature membrane failure.
Internally, the use of DWI-approved repair materials ensures continued compliance with potable water standards, while carefully detailed joint sealing protects against future leakage paths. The controlled installation environment and high standard of surface preparation underpin the durability of the works. Overall, the scheme reduces future maintenance requirements, enhances structural resilience and ensures the reservoir remains fit for purpose as part of Severn Trent Water’s long-term infrastructure portfolio.
