Overview of works
Claret Lining Division, working on behalf of Anglian Water’s IMR WR Alliance, delivered a major sewer rehabilitation programme across the Suffolk villages of Snape and Yoxford.
Following extensive deterioration caused by hydrogen sulphide (H₂S) corrosion, both gravity sewer networks required urgent intervention. Rather than undertaking large-scale open-cut replacement works, Claret developed a trenchless rehabilitation solution that protected environmentally sensitive habitats and delivered significant cost and carbon savings.
The scheme involved the renovation and replacement of more than 4.6km of gravity sewer infrastructure, which was a sustainable and cost-effective alternative to traditional excavation methods.
Key challenges
- Extensive asset deterioration caused by decades of H₂S corrosion
- Emergency infrastructure failures, including sewer collapses and significant void formation
- Environmentally sensitive locations with protected wildlife and rare plant species
- High groundwater levels making open-cut replacement complex and costly
- Community impact, including the need to minimise road closures and disruption to local businesses
- Project costs, with open-cut replacement estimated at more than £600 per metre compared to approximately £130 per metre for rehabilitation solutions
Our approach
Detailed network assessment
Following emergency repair works in Snape, Claret completed comprehensive CCTV surveys across both sewer networks to establish the extent of deterioration.
The surveys identified:
- Missing soffits across the first 870m of sewer in Snape
- Three semi-collapses requiring immediate repair
- Significant Grade 5 deterioration across large sections of both networks
- Multiple voids surrounding existing pipework
Trenchless rehabilitation strategy
A cured-in-place pipe (CIPP) lining solution was selected to rehabilitate the majority of the network while avoiding extensive excavation.
Key elements included:
- Rehabilitation of approximately 2,600m of sewer in Snape
- Rehabilitation of 2,017m of sewer in Yoxford
- Localised open-cut repairs only where necessary
- Assessment of 49 existing manholes, with several incorporated into the lining scheme and subsequently abandoned
- Post-installation grouting to stabilise voids and prevent future ground movement
Collaborative delivery
The project was delivered in partnership with Anglian Water, local authorities, environmental stakeholders and community representatives to ensure operational, environmental and social objectives were achieved.
Environmental management
Environmental protection was a key driver throughout the project.
The affected areas lie within environmentally significant fenland habitats that support a variety of protected and rare species, including:
- Heath spotted orchids
- Southern marsh orchids
- Water voles
- Amphibian populations
- Wintering wading birds
Extensive excavation posed significant risks to these habitats through:
- Damage to wet grassland flora
- Soil compaction and peat degradation
- Hydrological disruption
- Disturbance to protected wildlife
To mitigate these risks, Claret adopted trenchless rehabilitation techniques that eliminated the need for excavation across sensitive areas.
Additional measures included:
- Installation of protective barriers to prevent wildlife entering work areas
- Use of environmentally sensitive lining resins
- Ground stabilisation through targeted void grouting
- Continuous consultation with conservation stakeholders
Suffolk Wildlife Trust praised the approach, recognising the team’s commitment to protecting the local environment while delivering essential infrastructure improvements.
Environmentally sensitive materials
Specialist lining resins were selected to prevent any potential contamination or leaching into surrounding soils and groundwater during installation.
Void stabilisation
Following rehabilitation, grout was injected into known voids surrounding the sewer network to:
- Prevent future subsidence
- Improve long-term structural integrity
- Protect surrounding landscapes
- Enhance network resilience
Significant carbon reduction
The trenchless solution delivered a 93% reduction in carbon emissions compared with traditional open-cut construction methods.
Community impact
Minimising disruption to residents and businesses was a priority throughout the project.
To reduce inconvenience:
- Existing road closures were fully utilised to complete additional rehabilitation works
- No unnecessary additional traffic restrictions were introduced
- Diversion routes were carefully managed to protect local businesses
- Stakeholder communications provided regular updates to residents and interested parties
- Detailed information was shared regarding environmental protection measures and project benefits
The project attracted significant interest from local media, community groups and political stakeholders.
Outcomes
Infrastructure improvements
- More than 4.6km of sewer network rehabilitated
- Multiple collapses and structural defects resolved
- Long-term resilience significantly improved
Environmental benefits
- Sensitive habitats protected from excavation works
- Rare plant species safeguarded
- Wildlife disruption minimised
- Carbon footprint reduced by 93%
Community benefits
- Reduced road closures and traffic disruption
- Continued support for local businesses
- Enhanced communication and stakeholder engagement
Financial benefits
- Rehabilitation costs significantly lower than open-cut replacement
- Reduced construction programme
- Improved overall project efficiency
Safety & compliance
Health, safety and wellbeing remained the highest priority throughout the programme.
The project was delivered in accordance with all applicable legislation and CDM requirements, supported by:
- Project-specific Construction Phase Plans
- Detailed Risk Assessments and Method Statements (RAMS)
- Competent and fully trained operatives
- Daily site inspections and audits
- Continuous client oversight
Safety performance
· Zero accidents
· Zero incidents
· Zero dangerous occurrences
Through close collaboration with Anglian Water and environmental stakeholders, Claret Lining Division delivered a resilient long-term solution that avoided extensive excavation works and stands as an excellent example of how modern rehabilitation techniques can transform the delivery of critical utility infrastructure.