Project Title

Tolmount Gas Pipeline


Appointed to design and build both the temporary and permanent works associated with the build of a drive shaft and a 146m long microtunnel, as part of the Tolmount Gas Pipeline Project.


Main Contractor:
32 weeks
  • This project was entirely resourced and managed with our own internally owned Group assets,
  • The Iseki machine was recovered form a cofferdam within the foreshore under tidal conditions,
  • The team worked though tough conditions and championed our LIFE safety values & behaviours, with no major incidents.

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Project Overview

Joseph Gallagher was appointed to design and build both the temporary and permanent works associated with the original scope of works, which involved the build of a permanent (drive) shaft and a 146m long microtunnel as part of the Tolmount Gas Pipeline Project. The shaft was a 21m deep jacked caisson 5.5m id. The microtunnel was 1.2m id and 146m in length.



Working with Centrica Storage Limited (CSL) live gas handling facility, which harbours gas from pipelines from the North Sea proved challenging from both a logistical perspective and the team getting accustomed to new procedures outside of what they were use to. However - the PM made sure all the team understood what was expected of them through regular briefings and opportunities for the team to spend time with CSL representatives.

Adaptions had to be made to diesel and electric plant which included adding spark arrestors and chalwyn valves.

JGL worked closely with SAIPEM during the mobilisation stage to understand the processes and procedures of the terminal. This collaborative approach formed a good working relationship from the beginning to enable approval of documentation and the issue of various work permits within a week which was very challenging within a live terminal.


Added Value Contributions from JGL

The team made extra efforts to liaise with CSL and their environmental representatives to better understand the procedure and to ensure no delays would be incurred in the terminal. CSL were invited to spend time with the site team to learn about the shaft excavation procedures during the works to help facilitate these new requirements.

Wastewater went through a filtration system prior to discharge. The water was collected within the CSL holding pond prior to discharge. The tunnelling works re-used the water generated within the excavation of the tunnel into 2no Iseki settlement tanks which meant sourcing water from elsewhere was not required.

This water was also used for the grouting of the shaft annulus.

To hear about our experiences and how we can help you.

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