Welcome to our first e-zine of 2015, to update you on the progress of the Greater Dublin Drainage Project (GDD), upcoming activities and details of environmental surveys being undertaken as part of the ongoing preparation of the Environmental Impact Statement (EIS).

Tide and Current Survey

A marine tide and current survey is required so that the GDD Project Team can gather information about the movement of tides and currents, particularly in the location of the proposed outfall, 1km north-east of Ireland’s Eye. Information obtained by the surveys will enable the team to understand how clean, treated wastewater would move around and disperse in the sea after it is discharged from the outfall. Monitoring equipment called Acoustic Doppler Current Profilers (ADCP), a type of meter that measures sea currents, will be installed for a minimum continuous period of 30 days to measure sea currents. These will be placed on anchored platforms on the sea bed at two locations and each platform will be marked with a buoy.

A dye trace and drogue tracking survey will be carried out. The dye trace survey will be carried out at the end of February/beginning of March, when a fluorescent dye will be released into the water so that we can determine the direction and speed of sea currents and measure how fast the dye dilutes and spreads out or disperses in the water. The dye may be visible in the sea during this time, like in the picture below, and is a standard method routinely used in marine tide and current surveys.

Picture of fluorescent dye released into the sea during the dye trace survey that took place for GDD on 26th July 2012. Lambay Island is visible in the background of the photo.


Cone shaped plastic buoy type implements called ‘drogues’ will be placed in the water and tracked for up to 13 hours at a time to determine current direction and speed of dispersion and dilution.  They will contain reflectors and flashing beacons to highlight their location to water users.

Appropriate Assessment

The EU Habitats Directive requires that a study called an Appropriate Assessment (AA) be carried out for any project that is considered likely to have a significant impact on a Natura 2000 site (a European network, established under the Habitats Directive, of nature protection areas. The network is comprised of Special Areas of Conservation (SAC) and Special Protection Areas (SPAs)).  For GDD, the assessment is required to assess any potential impacts of the project on Natura 2000 sites in the study area, including the Rockabill to Dalkey Island Special Area of Conservation (SAC). A number of ecological surveys are required both on land and in the sea. The results of these surveys will be used by the GDD Project Team’s Ecologists to prepare a Natura Impact Statement (NIS), and to inform the ecology chapter of the overall Environmental Impact Statement. More information about some of these surveys is provided below and will be updated over the coming months.

Marine Mammal Surveys

A survey of marine mammals commenced in February in the area that extends between Portmarnock and Ireland’s Eye, and will be completed over a 24-month period. The harbour porpoise is a small marine mammal (it’s a cetacean which are marine mammals commonly known as whales, dolphins and porpoises) and is the principal conservation interest of the Rockabill to Dalkey SAC. As this mammal’s name suggests, it likes to stay close to the coast and is sometimes called a “sea pig” originating from its Irish name Muc Mhara. It has a small round nose, is dark grey across its back with a paler, white belly and has a small fin on its back. Like all cetacean species, it is legally protected under Annex II of the Habitats Directive. The survey will involve mammal observers recording visual sightings of marine mammals in the area and to supplement their information, a number of moored marine data buoys have been deployed to gather information for the survey.

Marine mammals use sound to help them to find and capture their food and do this by producing sounds that are reflected back to them when they strike an object – this is called echolocation.  Echolocation is important for marine mammals as it helps them to find their food at night or when water conditions are dark and difficult for them to see in. Underwater microphones will be used to detect the presence of cetaceans along the line of the proposed outfall pipe.

Picture of a Harbour Porpoise ©Simon Berrow (IWDG)

Picture of a short-beaked common dolphin ©M. de Boer

Bird Surveys

Birds are an important and popular wildlife resource and act as important indicators of the health of our environment.

Surveys of terrestrial (land-based) over-wintering (or non-breeding) bird populations are currently underway along the land section of the pipeline route. The surveys are being carried out by experienced ornithologists, i.e. ecologists who specialise in the study of birds, and will run until March 2015. The surveys will be repeated again between next January and March 2016. Surveys of terrestrial breeding birds along the land section of the pipeline route are scheduled to commence in April 2015. Marine bird surveys of Baldoyle Bay and from coastal vantage points at Ireland’s Eye and Portmarnock commenced in December 2014 and will continue to be carried out until 2016.

EZINERed Throated Diver 1_SS

Picture of a Red Throated Diver which is a Winter visitor to all Irish coasts from September to April.


Picture of a bird surveyor in action

Badger Surveys

Surveys to identify any signs of badger activity and their habitat, both on the site of the proposed Wastewater Treatment Plant in Clonshagh (Clonshaugh) and along the route of the proposed pipeline, commenced in January and are expected to be completed by the end of February/beginning of March. The survey will follow the standard methodology, which involves recording the following signs of badgers: badger paths, footprints, dungpits, hairs, scratching trees, bedding and setts. Badgers are protected under the Wildlife Act 1976 and Wildlife (Amendment) Act 2000. The EIS will include, where necessary, any measures that would need to be taken during construction of the pipeline to protect any identified badger population and its habitat.

Update on the Foreshore Licence Public Consultation

An application for a Foreshore Licence (reference FS006292) was made by the Project Team to the Department of the Environment, Community & Local Government (DECLG) for permission to undertake investigative surveys in the foreshore. The surveys will obtain information about the type of soil and rock that lie beneath the sea bed and will inform the detailed design and construction method of the marine outfall. A statutory public consultation process was held by the DECLG between 11th December 2014 and 20th January 2015 inclusive. The GDD Project Team is currently reviewing and responding to the submissions received. The application and associated information remain available to view at the DECLG website.

Contact the GDD team

As always, people can continue to contact the Project Team with feedback or questions, using our contact information below. The project website will be updated with information (such as progress of the environmental surveys and frequently asked questions) so please check back regularly. Further public information events will be held over the coming months and details of these will be communicated via this e-zine, the website and via the local media.