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Building Europe’s Longest Pipeline Tunnel

An extraordinary story of the longest tunnel in Ireland and the longest gas pipeline tunnel in Europe.

“Fionnuala” & The Corrib Tunnel (Summer 2013)

The Corrib Tunnel, a 4.9Km passage under Sruwaddacon Bay (a special area of conservation) presented an extraordinary engineering challenge for Shell and its contractors. Fionnuala, a tunnel boring machine from Germany was used to construct this section of the onshore pipeline route. Follow Fionnuala’s journey from Germany to when she commenced tunnelling activities at Aughoose.

Building the Corrib Gas Onshore Pipeline Tunnel

Approximately 4.9km of the Corrib Gas Onshore Pipeline will be constructed within a tunnel. The building of the tunnel requires the use of a large tunnel boring machine (TBM).

Excavation of the tunnel will be in one direction, starting at a launch pit on a SEPIL-owned site in the townland of Aughoose and running to a reception site in Glengad near where the offshore pipeline reaches land.

The tunnel will have an external diameter of 4.2m and an internal diameter of 3.5m and will run at depths of between 5.5m and 12m under Sruwaddacon Bay. When constructed, the tunnel will be the longest tunnel in Ireland and the longest gas pipeline tunnel anywhere in Europe.

“Fionnuala” – the Corrib TBM

In July 2012 Fionnuala, the tunnel boring machine which would be used on the Corrib Natural Gas project began her journey from Schwanau, Germany to Aughoose in Co. Mayo. The TBM took more than a year to design and build. The single shield TBM is 140m long, weighs almost 500 tonnes and comprises 14 sections.

The 28-tonne cutter head drills under the bay using a combination of cutter discs, scrapers and buckets and requires two 400kw motors to turn it.

Following in a long tunnelling tradition of naming TBMs, the Corrib TBM has been named ‘Fionnuala’ after the female of the Children of Lir, one of the legends most closely associated with the Erris region.