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Successful completion of Cobh to Monkstown Estuary Crossing Contract

Uisce Éireann has completed the Cobh to Monkstown Estuary Crossing as part of the Cork Lower Harbour Main Drainage Project as it works, in partnership with Cork County Council, towards ending the decades-long practice of discharging raw sewage directly into Cork Lower Harbour.

This landmark engineering feat involved two of the longest horizontal directional drills ever carried out in Ireland under the Lee Estuary. These drilled bores allowed the installation of sewer pipelines 60m under the Lee Estuary - creating a vital connection between Cobh and Monkstown. This connection will allow the raw sewage from Cobh town to be transferred for treatment, once work on the Cobh Town Networks contract is complete in 2021.

The completion of this latest stage of the project means that Monkstown Park can be handed back to the local community complete with local upgrades and improvements.

In addition, O'Connor Utilities Limited, working on Uisce Éireann's behalf, has won the inaugural Ervia Major Projects Contractor Safety Award for the safe delivery of this contract. 

Déaglán Healy, Project Manager for Cork Lower Harbour Main Drainage Project, said: "This is another important milestone in our project working towards ending the discharge of raw sewage into Cork Harbour with all the environmental, social and economic benefits that will bring."

"We would like to particularly thank the local community for their continuing support. Their patience and cooperation with our contractor, O'Connor Utilities, in partnership with Long O'Donnell, Nicholas O'Dwyer and our own Uisce Éireann project team, has greatly contributed to the safe and successful completion of these works."

"We are also delighted to be able to return the reinstated Monkstown Park, with a new surface and multi-use games area to the basketball court, additional drainage to the levelled and reseeded football pitch, and a new wildflower area and bug hotel. The bug hotel has been constructed using sections of the pipe type that has been installed under the Estuary, to represent how these pipes are working underground where we cannot see them - bringing raw sewage for treatment, leading to better water quality in the sea at Monkstown and all the Cork Lower Harbour area - improving the environment we all live in."

"Safety is at the heart of everything we do and we are delighted to acknowledge the leadership, determination and committed approach of O'Connor Utilities Limited towards promoting safety around all their work on the Estuary Crossing contract."

Work is progressing well on the Cobh Town Networks Contract, with construction well advanced on the five pumping stations, and over 4.6 kilometres of the total seven kilometres of sewer pipes laid to date.  When works in Cobh are complete in 2021, the raw sewage from Cobh town will be collected and transferred for treatment via the Cobh to Monkstown Estuary Crossing to Monkstown pumping station, from where it will be pumped to Shanbally Wastewater Treatment Plant for treatment before its safe discharge to the harbour.

When construction on the Cork Lower Harbour Main Drainage Project commenced in 2015, the equivalent of 40,000 wheelie bins of raw sewage was discharging into the Harbour every day. We are now treating the equivalent of 30,000 of those 40,000 wheelie bins by completing the Shanbally Wastewater Treatment Plant and pipelines and pumping stations on the south side of the harbour so that wastewater from Ringaskiddy, Crosshaven, Carrigaline, Passage West and Monkstown is now being treated.

When all the Cork Lower Harbour Main Drainage works are complete in 2021, the project will, in compliance with the Urban Waste Water Treatment Directive, treat all wastewater from the agglomerations of:

  • Ringaskiddy-Crosshaven-Carrigaline;
  • Ringaskiddy village;
  • Passage West-Monkstown;
  • Cobh town.

This means 20,000 homes and businesses will be connected to the new scheme and that raw sewage from these areas will no longer be discharged into the harbour, positively impacting the local economy and greatly improving the amenity value of the Cork Lower Harbour for the surrounding communities.

Uisce Éireann is working at this time, with our local authority partners, contractors and others to safeguard that the health and well-being of staff and the public and to ensure the continuity of drinking water and wastewater services.

For more information on the project, information days and works information please contact the project team at or view our Cork Lower Harbour Main Drainage Project section.

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