Programme overview
As the national body responsible for the country’s gas network, we are occasionally required to facilitate changes to the gas system to support major new public and private infrastructure developments, deemed to be of significant economic and/or social value.
In 2025, we decommissioned a 1.2km section of Transmission (high pressure) national gas pipeline to facilitate the construction of the M28 Cork to Ringaskiddy motorway project.
Transport Infrastructure Ireland required this modification as the existing pipeline would have crossed and conflicted with construction of the upgraded motorway route.
Working with our construction partner, Murphy, the project involved isolating and de-gassing a section of the Mahon to Ringaskiddy high pressure pipeline before decommissioning it. This section was feeding two Above Ground Installations (AGIs), one of which had already been previously decommissioned. The remaining commercial customer being supplied by the other AGI was able to be switched to our Distribution (low pressure) pipeline before the works were completed. This meant there was no interruption to supply.
Project highlights
Works on this project commenced on site in October 2024 and were completed in April 2025. Project features included:
- A ‘stopple’ operation was required to isolate the gas supply at Barnahley. This involved a temporary plug inserted into the pipeline to stop gas flow, which allowed a short section of pipe to be cut out and a new valve arrangement to be installed, meaning the pipe can be easily connected to in future without another stopple operation.
- A 1.2km section of the existing Mahon to Ringaskiddy transmission pipeline was decommissioned.
- The previously decommissioned ‘Irish Steel’ AGI was dismantled.
- Our customer being supplied by ‘Loughbeg’ AGI was transferred from transmission (high pressure) pipeline to distribution (lower pressure) pipeline and the AGI modified accordingly.
- Reinstatement was undertaken at both AGI sites.
All these works were carried out while also maintaining supply, ensuring citizens and businesses in the area did not suffer interruptions to their gas supply.
What is a Pipeline Diversion?
Transmission pipeline diversion projects are required when a third party needs to complete construction or industrial/residential development works over land where gas pipelines are located. This involves Gas Networks Ireland moving or altering the gas pipeline route so that it is safe to proceed with construction.
The requestors can be public or private organisations and this work is key to supporting economic and social progress because the works are generally linked to new national or commercial infrastructure projects such as factories or motorways.
Timelines on these projects are usually critical to avoid delivery delays. These projects are entirely funded by the third party.