Final Settlement Tank Internal Components Refurbishment
Uisce Éireann
Design and Build
Co. Waterford, ROI
CAW successfully delivered the refurbishment of Final Settlement Tank (FST) internals at Waterford Wastewater Treatment Works, ensuring long-term operational resilience in a challenging saline environment.
The project formed part of an ongoing programme of upgrades at the site, which serves a population equivalent of approximately 190,000 and plays a critical role in protecting the River Suir estuary through advanced wastewater treatment processes.
Project Highlights
Project Overview
Uisce Éireann sought to bring forward a project to maximise the performance and long-term resilience of the final settlement tanks at the Waterford Wastewater Treatment works.
Following an independent engineering assessment, CAW proposed that the full replacement of all internal tank launders and outlet hoppers would be the optimal solution. Building on previous successful upgrades to FSTs 1 and 3, CAW was tasked with completing the refurbishment of the remaining tanks (2 and 4) while maintaining operational continuity at the live plant.
Proposed Solution
CAW proposed and delivered a refurbishment solution, working closely with specialist suppliers and subcontractors to design, fabricate and install corrosion-resistant components more suited to the site conditions.
The use of high-grade stainless steel ensures significantly improved durability and reduced maintenance requirements, supporting the long-term resilience of the plant.
Key elements of the scope included:
- Replacement of all internal launder channels and outlet hoppers
- Installation of 316 stainless steel components to withstand high chloride environments
- Upgrade of scraper systems, support brackets, hangers, scum boxes and scum boards
- Precision alignment using laser levelling to ensure accuracy across all installations
- Safe lifting and installation of prefabricated sections using specialist crane equipment
- Installation of watertight connections using bolted joints with rubber gaskets
Project Delivery
The works were carefully planned and executed within a fully operational wastewater treatment environment. CAW maintained continuous treatment performance throughout the programme, ensuring no disruption to compliance or discharge standards.
The project was delivered efficiently using a staged approach:
- Tank isolation, drainage and cleaning
- Removal of existing corroded components
- Installation of new prefabricated stainless steel systems
- Testing and return to service in line with programme requirements
Health & Safety
CAW acted as Project Supervisor Construction Stage (PSCS), maintaining the highest standards of health and safety management throughout the project and achieving a zero-incident record with no accidents or near misses during over 1,200 man-hours worked. This was delivered through:
- Comprehensive method statements and risk assessments developed
- Detailed lifting plans coordinated across all stakeholders
- Close collaboration with plant operations and HSQE teams
The Outcome
The successful completion of the refurbishment programme delivered:
- Full restoration of all Final Settlement Tanks to operational service
- Increased resilience to saline and corrosive conditions
- Improved reliability and reduced future maintenance requirements
- Continued compliance with EPA and Uisce Éireann discharge standards
- Zero disruption to wastewater treatment operations
The upgraded assets now support the ongoing performance of Waterford Wastewater Treatment Works, which provides advanced primary, secondary and tertiary treatment to protect the River Suir and the surrounding environment.
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