VolkerInfra was awarded a contract with ABB to construct a new interconnector between Ireland and Wales for EirGrid plc. Ireland has plans to expand the wind power generation and the link gives the potential to export excess energy to the UK market. The new link also gives security of supply to the Irish grid and allow Ireland and Britain access to more competition.
The East West Interconnector Project (EWIP) involved the installation of HVDC cable both under the sea and on land. The Interconnector will have 186km laid on the seabed of the Irish Sea, 30km of land cable in North Wales, and 45km in Ireland.
The new Interconnector utilises 2 no. 200kV HVDC Light cables (total 372km) supplied by ABB with a capacity of 500MW, connecting two new converter stations also being built by ABB on both sides in Woodlands, Meath, Ireland and Shotton, Deeside, UK. VolkerInfra wwas appointed by ABB to construct the land cable on both the Irish and UK sides.
The cable route was optimised as the cable pull length was increased to up to 1200m, reducing the number of pulling and cable joints. Furthermore, trial pits and route analyses were performed to establish the best route within the available corridor.The majority of the cable route is located in local roads which resulted in complicated schemes of road diversions and road closures. Close co-operation was required with local authorities and communities to minimise the impact of the work on their daily lives. The trenching works were performed using excavators and cutters. In Wales, most of the excavated materials were stabilised and re-used as backfill.
For the cable installation, special drum trailers were fabricated as well as a special pulling winch. In addition, push-pull machines were used to reduce the pulling loads on the cables. Following installation of the cables the ducts were filled with cable grout with low resistivity and long term lifespan without segregation. The whole project involved engineering input from Wales, Ireland, England, The Netherlands and Sweden, bringing together a wealth of international skills and trades all working together to deliver one of the biggest high voltage cable construction projects in Europe.