Arklow Waste Water Treatment Plant
Arklow, Ireland
Merit Award, Water/Wastewater
Presented by Ayesa Engineering
Owner: Irish Water – Uisce Eireann / Wicklow County Council
Principal Design Firm, Civil Engineer: They will try
Contractor: Ward & Burke Construction Ltd.
Structural Engineer: Tobin Consulting Engineers
MEP Engineer: Nicholas O’Dwyer
Marine works contractor: Van Oord Ireland Ltd.
Architect: Clancy Moore Architects
Consultants: ARUP; HaskoningDHV
Since the late 1980s, the Irish town of Arklow, about 90 minutes south of Dublin, has struggled to build a wastewater treatment plant, but delays and setbacks held back the development of a facility. Before the project was finally commissioned in 2025, raw sewage was discharged directly into the Avoca River and the Irish Sea.
The $150 million project was built on limited derelict land, bordered by a working harbour, residential areas and the Nineteen Arches Bridge, built in the 1750s and a heritage landmark as Ireland’s longest hand-made stone arch bridge. The project owners chose not to build a conventional floor plan and hired the architectural firm Clany Moore to design covered structures with roofs and facades.
The constraints required careful planning, sequencing and community involvement. The stacked plant design will allow 30% of the site to be dedicated to biodiversity. Other components of the project included 1.2 km of sewer interceptor tunnels under the river, a 900 m marine outfall installed offshore and a pumping station.
Started in 2021, the project was completed in November 2024, six months ahead of schedule and on budget.
