Sligo Water Treatment Works
Operations and Maintenance
Co. Sligo, Ireland
The state-of-the-art water treatment plant at Foxes Den in Sligo delivers approximately 16.5 million litres of drinking water per day to the population and businesses of the Sligo area. The raw water for treatment is extracted from Lough Gill, 3 kilometres southeast of Sligo and pumped via a 500mm pipeline at a rate of approximately 550m³/hr to the main treatment works.
CAW has managed the operation and maintenance of the Sligo Water Treatment Works on behalf of Uisce Éireann since 2001. We were the first private company to be awarded a Water Treatment Operations and Maintenance Contract in the Irish Republic.
During CAW's tenure, we were awarded and have completed two major upgrades to ensure compliance with the latest European and Irish Drinking Water Regulations, as well as Uisce Éireann’s process and engineering standards. This included an upgrade to enhance pathogen removal with a new UV treatment process and capacity boost that increased clean drinking water production by one-third.
Site Highlights
Site Highlights
Goals
CAW is committed to supporting Uisce Éireann’s to achieve its goals for water quality, environmental stewardship, and sustainability through continuous optimisation activity, providing expert consultancy, and delivering upgrades and improvement projects. Our commitments include:
- Assuring compliance with Drinking Water Regulations and Uisce Éireann’s standards.
- Ensuring continuous optimisation of plant performance and efficiency.
- Working to the highest safety standards.
- Consistent and uninterrupted provision of drinking water to the network.
Operations and Maintenance Service Provision
CAW is responsible for the full operation and maintenance of the Sligo water treatment facility and manages several complex processes and technologies to water is treated to the highest standards for consumption. These include:
- Clarification, which incorporates pre-dosing to speed up coagulation and flocculation, which involves before entering the Dissolved Air Flotation (DAF) process;
- Rapid Gravity Filtration;
- Conditioning involving UV disinfection and dosing of appropriate agents to ensure water quality before being passed to the treated water reservoirs;
- pH correction;
- Treated water storage within a 15,000m³ storage reservoir on site;
- Sludge management to include thickening and dewatering.
CAW Provides:
- 24/7 operational maintenance, including emergency repairs;
- Proactive asset management to optimise performance and maximise asset lifespan;
- Compliance with EU and Irish Water Drinking Water Regulations;
- The highest standards of on-site health and safety in line with CAW and Uisce Éireann policies;
- Compliance with environmental plans to safeguard the local community and environment;
- Management of the Capital Replacement Fund in collaboration with Uisce Éireann;
- Regular reporting under the Performance Management System of the Water Services National Training Group (WSNTG);
- Contributions to social and environmental improvements to benefit the local area;
- Consultancy on innovative strategies for performance improvement and carbon emission reduction.
Milestones and Highlights
2016 Upgrade to enhance pathogen removal by integrating a new UV treatment process
In 2016, CAW managed a comprehensive upgrade, to ensure the 11,000 m³ of water treated water daily complied with updated European Drinking Water Regulations. The project ensured efficient, reliable, and automated operations during the upgrade. Key enhancements included upgrades to filtration systems, installation of advanced UV disinfection technology for Cryptosporidium inactivation, and improvements to chemical dosing and water quality control systems. This modernisation effort supports sustainable water treatment and robust pathogen compliance for the region.
Capacity upgrade to increase production of clean drinking water by a third
In 2021 CAW completed works to increase the treatment capacity of the plant by 5.5 million litres, from 11 million litres per day to 16.5 million litres per day. CAW was awarded the contract in 2019 for the design, construction, commissioning, testing, and maintenance of the plant upgrade to ensure a minimum output of 825m³/hour once complete.
Key works included upgrading the pumping capacity, installing new Dissolved Air Floatation units and filtration systems, optimising the treatment process, and replacing mechanical and electrical sludge treatment systems. The project also involved decommissioning the gas chlorination system, upgrading SCADA and control systems, and expanding the inter-link pumping station to the Cairns Hill Reservoirs, with associated site and landscaping works.
These works were delivered during the COVID-19 pandemic, incorporating the necessary safeguards to protect employees and contractors. This complex project, involving significant structural changes was delivered successfully with no disruption to water supply.
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