Cork Lower Harbour Main Drainage Scheme, County Cork, Ireland


Cork Lower Harbour Main Drainage Scheme (LHMDS)

The Cork Lower Harbour Main Drainage Scheme (Cork LHMDS) includes the development of a new wastewater treatment facility in Shanbally village, County Cork, Ireland, along with associated sewage collection facilities with an estimated total investment of €91m ($102m).

The project was initiated to enhance the water quality in Cork Harbour, a natural harbour located near the River Lee in County Cork by eliminating the discharge of untreated sewage that currently enters the harbour from its surrounding areas.

It is being implemented by Irish Water, Ireland's state-owned water utility company, which took over the responsibility of developing water and wastewater services in January 2014, and Cork County Council.

The groundbreaking ceremony for the wastewater treatment facility was held in August 2015 and the construction is expected to be completed by late 2016.

Objectives and benefits of Cork LHMDS

The Cork Lower Harbour Main Drainage project is considered vital as it will significantly improve the water quality of the Cork Harbour.

Further, a wastewater treatment plant is mandated under both European and National Legislation to improve the health, integrity of the environment and quality of water in accordance with the European Union's Urban Wastewater Treatment Directive.

As a result, the project will avoid substantial penalties by meeting the quality standards set by the regulatory bodies.

Scheme and capacity details

The scheme includes construction of a new wastewater treatment facility in Shanbally, installation of eight new pumping stations and upgrade of four existing pumping stations at West Beach (Cobh), Carrigaloe, Monkstown and Raffeen, laying approximately 30km of new/upgraded sewers and renovation of existing sewers.

Raw sewage from all the connected areas will be collected through new pipes and redirected to the new plant, which will treat and safely discharge the wastewater into the Harbour through the existing IDA outfall pipeline at Dognose Bank.

Approximately 49,000PE of raw sewage is being discharged into the Harbour currently. The new plant will have a designed treatment capacity of 65,000PE initially, which is expandable up to 80,000PE.

Project background and timeline

The population of Lower Cork Harbour, which includes the areas of Cobh, Carrigaline, Passage West/Monkstown and Ringaskiddy, is expected to rise significantly by 2035. The area is currently served by a sewer network comprising combined sewer systems and new housing estates. However, the untreated sewage from all these areas is being discharged into the Harbour, significantly affecting its water quality.

In 2004, the area from Lee Estuary/Lough Mahon to Monkstown was designated as sensitive amending the existing urban waste water treatment regulations. In the same year, a preliminary report (PR) that defined the requirements and recommendations for the project was prepared by a project team appointed by Cork County Council.

The PR was later updated in 2008, according to 2006 census, and a final draft was submitted in February 2010, which was approved by the department of environment, community and local government in March 2012.

"The project was initiated to enhance the water quality in Cork Harbour, a natural harbour located near the River Lee in County Cork."

Environmental impact statement (EIS) for the plant was approved by An Bord Pleanála, Ireland's statutory board that determines applications for strategic infrastructure developments, in 2009. The board also approved the planning permission for the project in 2010.

Third-party experts, including Nicholas O'Dwyer and AMEC Consulting Engineers, appointed in the project team in 2013, conducted studies to gather information to support the tendering process of the project.

Contractors involved

The project is divided into five contracts. These comprise the wastewater treatment, Cobh network, estuary crossing contracts, in addition to the Passage West/Monkstown and Carrigaline/Ringaskiddy contracts.

The wastewater treatment plant contract includes the development of the new plant and connecting the wastewater flow from Carrigaline and Crosshaven to the plant.

The Cobh network contract seizes all the existing raw sewage outfalls into the town of Cobh and transfers them to the new plant. The Estuary crossing contract transfers flows from Cobh to the network in Passage West/Monkstown for onward transfer to the new plant.

The Passage West contract will seize all the existing raw sewage outfalls into the Passage West and then transfer to the new plant and pumping station. The Carrigaline contract intercepts the outfalls in Ringaskiddy and Coolmore and carries them to the new plant. The contract also includes upgrade works in Carrigaline.