Grand Canal Storm Water Outfall Extension
Dublin City Council is progressing plans to complete the storm water outfall extension at Grand Canal Dock, to improve water quality in the area.
Dublin City Council is progressing the second phase of the Grand Canal Storm Water Outfall Extension. The completed project will see the current storm water overflow being channelled from the confined Grand Canal Dock and discharged into the River Liffey. This project is being co-funded by Irish Water.
What are the benefits of this project?
The works will:
- Improve water quality in the Grand Canal Dock.
- Enhance the amenity & recreational value of the area.
What is involved as part of this project?
A planning application will be submitted in late 2021 detailing the proposed works including:
- Installation of underwater pipes between the current outfall within the Docks and the proposed outfall to the River Liffey on Sir John Rogerson’s Quay.
- Connections to the section of outfall pipeline already in place on Asgard Road.
- Construction of an outfall structure at Sir John Rogerson’s Quay.
What are the next steps?
This project is currently at planning stage and a planning application is due to be submitted to An Bord Pleanála in late 2021.
Why is this project needed?
The Grand Canal Tunnel was constructed in the early 1970’s in order to;
- Transport foul effluent from the newly expanding suburbs in the west of the city to the Wastewater Treatment Plant in Ringsend.
- Provide a channel for flow from the storm sewers and overflows from the combined sewers.
- To carry storm relief flows from the Poddle and Swan Rivers thereby reducing the risk of flooding in those areas.
In the early 1990’s, arising from development and upgrading of the dock and its environs, the Office of Public Works requested that Dublin City Council remove the storm water discharge from the dock. It was decided the project would be done in 2 phases.
Phase 1 of the scheme was completed in 2002 with the construction of a pipeline along Asgard Road between Hanover Quay and Sir John Rogerson’s Quay. Provision was made for the future connection of the Phase 2 pipelines on either side.
A Section 25 Certificate for Phase 2 of the Grand Canal Dock Surface Water Outfall was obtained in March 2007 from the Dublin Docklands Development Authority (DDDA). In 2010 Phase 2 proceeded through stakeholder consultation, identification of constraints, detailed design and a final design was developed. The Phase 2 design proceeded to tender documents, but the project was put on hold in 2012.
Water quality in the Grand Canal Dock has been adversely affected by the existing stormwater outfall discharging foul sewerage into the Basin during periods of high rainfall and the Grand Canal Basin is regularly impacted by microbiological pollution, after heavy rainfall events.
Irish Water, Dublin City Council and Waterways Ireland established a working group in 2017 to determine the cause of ongoing pollution. It has been determined, following testing and research, that the primary source of pollution is the discharge from the surface water section of the Grand Canal Tunnel.
It was concluded that the existing discharge point of the Grand Canal Tunnel outfall into the docks must be removed. By removing the pipeline from the Basin, this will greatly reduce pollution within it.
As the DDDA was dissolved in 2015, the Section 25 Certificate that was previously granted, has been rendered void. Hence planning permission must now be sought.
Where will the project take place?
The proposed project will install a new pipeline within the Grand Canal Dock to the River Liffey via Asgard Road together with the construction of an outfall structure to the River Liffey at Sir John Rogerson’s Quay. 450m of pipeline will be installed within the Grand Canal Basin and 100m of pipeline will be installed along the existing road and pedestrian infrastructure on Hanover Quay.
Figure 1: Grand Canal Stormwater Outfall Extension Location Map
What is the planning process for the project?
Dublin City Council intends to apply to An Bord Pleanála in 2021 for permission to implement the project. An Environmental Impact Assessment Report (EIAR) will be submitted to An Bord Pleanála as part of the planning application. As the competent authority for assessing and determining planning applications, An Bord Pleanála will carry out a statutory phase of consultation, during which the public and any interested body may make comments and observations to An Bord Pleanála on the project.
What is an EIAR?
An Environmental Impact Assessment (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.
Simply put, an Environmental Impact Assessment (EIA) is a process for anticipating the effects on the environment caused by a development. An Environmental Impact Assessment Report (EIAR) is the document produced as a result of that process.
When a project proposer submits its application for consent to An Bord Pleanála it must include an Environmental Impact Assessment Report (EIAR) describing the project and its anticipated effects on the environment.
When can the EIAR be viewed?
The EIAR will be submitted with the planning application and can be viewed online.
Will this project improve water quality in the Grand Canal Dock?
This project will improve water quality in the Grand Canal Basin. The Grand Canal Dock is under the control of Waterways Ireland, not Dublin City Council. It is not a designated bathing area and is not monitored by Dublin City Council. Bathing in the Dock is forbidden and is considered to be dangerous.
Grand Canal Dock is used for water sports such as kayaking and wind surfing.
Will you be engaging with members of the public?
Public Information Events will be held prior to the submission of the planning application, where members of the public will be welcome to learn more about the proposed project and meet members of the project team who will answer any outstanding queries local stakeholders may have. It is planned that this will take place in Q3 2021.
The proposal is to move the outfall from its current location within the Grand Canal Basin onto the River Liffey at Sir John Rogerson’s Quay. Why not deal with the sources of pollution upstream of the basin?
In Ireland, most urban areas are drained by combined sewer systems, which convey Wastewater and Stormwater in a single pipe. This is also common practice internationally. During heavy rainfall, stormwater flows can be several multiples (50+) of wastewater flows and it would not be practical to design piped systems to take this flow. During periods of heavy rainfall, Combined Sewer systems are designed to overflow occasionally and discharge diluted wastewater to nearby water bodies. This is considered good practice as long as the number of overflows is not excessive.
To remove all overflows upstream of the Grand Canal Basin would cause an unacceptable level of disruption and take years to design, procure and fund.
Will this project impact on the River Liffey, Dublin Bay and associated ecosystems?
A water quality model is currently being developed. This will assess the impact, if any, of various scenarios on the water quality of the River Liffey and Dublin Bay. This model is due to be completed in 2021 prior to the submission of planning permission. The results of this study will be available to view once completed.