The Ringsend Wastewater Treatment Plant is currently operating over its design capacity (the plant was originally designed to treat wastewater for a capacity of 1.64 million Population Equivalent (PE) but is now operating at a capacity of 1.9 million PE) and it needs to be upgraded to ensure that the Greater Dublin Area has appropriate wastewater treatment facilities to enable continued social and economic development.

In 2012, Dublin City Council obtained planning consent from An Bord Pleanála under the Strategic Infrastructure Development (SID) provisions of the planning and development acts. The planning consent was to expand the Ringsend Wastewater Treatment Plant to a capacity of 2.1 million population equivalent (PE) and to relocate the discharge of treated wastewater from the Ringsend Plant out into Dublin Bay, through the construction of a 9km undersea tunnel.

In January 2014, the responsibility for the Ringsend Wastewater Treatment Plant was transferred to us from Dublin City Council. An advanced nutrient reduction treatment technology has been identified that was not available as an option to Dublin City Council in 2012. This technology is known as Aerobic Granular Sludge (AGS) and would allow treated wastewater to remain and be safely discharged at its current location, avoiding the need to construct the 9km long undersea tunnel in Dublin Bay.

AGS technology is based on a naturally-occurring treatment process that takes place in our lakes, rivers and estuaries where micro-organisms and bacteria breakdown biodegradable pollutants. AGS technology allows for the breakdown of biodegradable pollutants at a faster rate than would happen in the natural environment. The process is carefully controlled at a wastewater treatment plant to achieve the required effluent water quality standards set by the Environmental Protection Agency, in accordance with relevant EU Directives. AGS is an advanced nutrient removal technology that is a further development of the activated sludge process.

AGS technology was not available for consideration at the time of the original planning application in 2012. Since this time, wastewater treatment plants using AGS technology have also come into operation in the Netherlands, Portugal, South Africa and most recently, in Clonakilty and Carrigtohill, Co. Cork.

We have conducted detailed testing and trials of the technology since April 2015 to treat the wastewater being received at the Ringsend plant. These trials have proved successful; confirming that wastewater treated by AGS technology can be safely discharged to the Lower Liffey Estuary and Dublin Bay.

If approved, the use of this AGS technology at Ringsend will maximise treatment capacity and efficiency at the plant.

The impacts of tunnel construction could be entirely avoided, including the 70,000 heavy goods vehicles involved in removing material excavated from the 9km long tunnel. Significant project savings will also be made by not constructing the undersea tunnel.

A much higher treated effluent quality would also be achieved and, even at full future capacity, emissions from the plant would be significantly lower than at present.

The revised project we are proposing also provides for the recovery of phosphorus (a non-renewable resource), this finite resource would otherwise be discharged to Dublin Bay with the loss of its re-use potential in agriculture.

An Environmental Impact Statement (EIS) is a document prepared by the proposer of a project that sets out the impacts (both positive and negative) which the proposed development would have on the environment. Normally, the first step in the preparation of an EIS is a ‘scoping’ study. During this stage the project proposer consults with statutory bodies, interested parties and the general public. The objective of the scoping exercise is to identify the environmental issues of concern which might arise during the construction and operation of the project. You can view our scoping document here.

An Environmental Impact Assesment (EIA) is the process of identifying, predicting, evaluating and mitigating the possible effects on the environment of a project before a decision is made whether or not to proceed with that project. The steps in the EIA process are set out in national and EU legislation. Most large-scale infrastructure projects are subject to EIA as part of their planning consent process.

When a project proposer submits its application for consent to An Bord Pleanála it must include an Environmental Impact Statement (EIS) describing the project and its anticipated effects on the environment. A period of public consultation then follows, during which the public and any interested body may make comments and observations to An Bord Pleanála on the project and its environmental effects. An Bord Pleanála must then undertake an environmental impact assessment of the project before making its determination on the application.

The Birds and Habitats Directives of the European Union (EU) set out various procedures and obligations including the establishment of Special Protection Areas (SPA) and Special Area of Conservation (SAC) for the protection of specific habitats and species. Collectively, the SPAs and SACs established throughout the EU comprise a network known as Natura 2000.

The Habitats Directive imposes a duty on Member States to consider the possible nature conservation implications of any project on the Natura 2000 site network before any decision is made to allow that project to proceed. This assessment procedure is known as Appropriate Assessment and is quite similar to the EIA procedure. It is normally undertaken at planning consent stage by An Bord Pleanála.

Like the EIA procedure, a document is prepared by the project proposer and submitted with its application for project consent. This document is known as a Natura Impact Statement (NIS). While there is significant overlap between the EIA and AA processes, it should be noted that the NIS and AA only consider and assess impacts on the Natura 2000 network and that AA is a separate legal consent process distinct from EIA.

Irish Water intends to apply to An Bord Pleanála in 2018 for permission to implement the revised project. The Board will then undertake an Environmental Impact Assessment (EIA) and an Appropriate Assessment (AA) of the project before making its decision on the application. The EIS and NIS will be submitted to An Bord Pleanála as part of the planning application. As the competent authority for assessing and determining planning applications, the Board will carry out a statutory phase of consultation, which will present you with a further opportunity to provide your feedback.

To keep informed about the progress of this application, and the project in general, please sign up to our Ringsend Wastewater Treatment Plant Upgrade Project by sending an email to

Back to the top