Stockton Install Galway HDD

Stockton Install Galway HDD

Challenging River Corrib Crossing Completed

During April 2016, Stockton commenced work on the River Corrib crossing project in Galway, Ireland, sub-contracted for GMC Utilities - principle contractor for SSE.

The project involved the installation of a 390 metre HDPE pipe-bundle beneath the River Corrib, with SDL utilising their 250 tonne drill rig to drill a bore of 28 inch to install the HDPE bundle - consisting of 3 x 200mm and 3 x 125mm pipes, at a site located close to the historic Menlo Castle, a Galway County Heritage site.

Drilling commenced from an entry-site on the Western bank of the Corrib, with an exit-point set within the National University of Ireland Galway (NUIG) campus. The aim of the HDD installation was in order to complete a 110kV grid connection to the SSE wind park west of Galway city.

As well as having a width of approximately 110 metres, the Corrib, which flows along a fault line where two rock types - granite and limestone - converge, is also a Special Area of Conservation (SAC).

These factors - combined with the ongoing activities at the University and the ruins of the medieval castle - resulted in the project presenting an array of logistically and technically challenging aspects.

In order to overcome these challenges, the HDD profile was designed as a continuous curve from the entry point, entering at 13 degrees to the horizontal and following a vertical radius of no less than 400 metres.

Two pilot holes were drilled, utilising a six and three-quarter inch down-hole mud-motor, powering an eigth-and-a-half inch tri-cone drill bit to follow the predetermined profile trajectory to the pre-planned exit point.

The first pilot hole had a 125mm HDPE line inserted to be used as a drilling fluid return line. The second was reamed in two stages to a 28 inch diameter to facilitate the insertion of the HDPE pipeline bundle.

Following the successful completion of the project, SSE Project Manager Paul Lloyd said: During the course of the project a number of day to day problems did arise which could have developed into something far worse but for the correct and timely response of Stockton’s personnel on site.

Stockton demonstrated a thorough knowledge of this field and an understanding of the critical design issues that must be addressed in order to successfully undertake a complex project of this nature.

At all times Stockton’s site personnel conducted their business in a safe professional and courteous manner and they were a pleasure to deal with. 

For any enquiries, please contact head office on 01924 242128, or email

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