Sewer pipes have been installed under the river Lee estuary, linking Cobh and Monkstown, marking a key milestone in a project designed to end the discharge of raw sewage into Cork Harbour.
The landmark engineering feat involved two of the longest horizontal directional drills ever carried out in Ireland.
In a project overseen by Irish Water, engineers spent months drilling horizontal bores under the river Lee from Cobh to Monkstown, to allow for the installation of around 60-metres of sewer pipes.
They will eventually allow the raw sewage from Cobh town to be pumped under the estuary, to a pumping station in Monkstown, from where it will be pumped to a treatment plant in Shanbally before its safe discharge to the harbour.
The completion of the underwater drilling means that Monkstown Park can also be handed back to the local community.
The Cobh to Monkstown Estuary Crossing is a vital part of the Cork Lower Harbour Main Drainage Project, which Irish Water began in partnership with Cork County Council, in 2015.
At that time, the equivalent of 40,000 wheelie bins full of raw sewage from around 20,000 homes and businesses in the lower harbour region was being discharged into the harbour every day.
Since then, a treatment plant at Shanbally, new pipelines and pumping stations have been built on the southern side of the harbour.
Irish Water says these new facilities are collecting and treating the equivalent of 30,000 wheelie bins full of raw sewage from the Ringaskiddy, Crosshaven, Carrigaline, Passage West and Monkstown areas, leading to substantial improvements in the harbour’s water quality.
Déaglán Healy, the project manager for the Cork Lower Harbour Main Drainage Project, thanked the local community for their support during the construction of the estuary crossing.
We have completed the Cobh to Monkstown Estuary Crossing as part of the Cork Lower Harbour Main Drainage Project. In partnership with @Corkcoco, we are working towards the ending of discharging raw sewage directly into Cork Lower Harbour. See https://t.co/YWDUwWIZDE for more.— Uisce Éireann - Irish Water (@IrishWater) December 15, 2020
“Their patience and cooperation with our contractor, O’Connor Utilities, in partnership with Long O’Donnell, Nicholas O’Dwyer and our own Irish Water project team, has greatly contributed to the safe and successful completion of these works,” he said.
“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 was built using sections of the pipe type that has been installed under the estuary.
Meanwhile, Irish Water says work is progressing well on the Cobh Town Networks Contract, with construction well advanced on five pumping stations, and around 4.6 kilometres of the planned seven kilometres of sewer pipes laid so far in and around the town.
The entire main drainage works are due to be complete before the end of next year.