Morgan Sindall Professional Services (MSPS) and its sister business Underground Professional Services (UnPS) is near to completing the Front End Engineering Design (FEED) for a 22km underground cable tunnel for the UK’s National Grid, one of the most technically challenging projects of its type ever proposed.Awarded the contract in September 2015, and having now completed a significant portion of the reference design, the team is now supporting National Grid through a public consultation, after which the energy provider will apply for a Development Consent Order (DCO) prior to issuing an invitation to tender.
The tunnel is an integral part of the North West Coast Connection (NWCC), a plan to connect and export electricity generated by Moorside – a proposed 3.4GW nuclear power station near Sellafield in west Cumbria. To minimise impact on the Lake District National Park, the power will be transmitted via a cable tunnel below Morecambe Bay’s seabed, between Barrow in Furness and Heysham. The cable tunnel will enable the National Grid network to be fed from the power station’s energy source.
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The proposed tunnel, circa 5m in diameter, will house two 400kV cable circuits to transport the electricity. Due to the strict ventilation requirements, and to ensure the high voltage (HV) cables do not overheat when fully loaded, an islet in the middle of the bay is proposed as a heat ventilation point and an emergency escape.
Neil Lyons, National Grid senior project manager, says MSPS and UnPS demonstrated innovative capabilities, critical for this project: “This project requires various bespoke tunnel construction methodologies and linings designs, an understanding of marine works, and all the associated challenges from both HV cable installation and operational point of view, all with safety being at the forefront.
“The team has supported us from the outset, adapting designs with multiple options to satisfy different stakeholder groups, and completing the reference design within a very tight timeframe. We now look forward to their continuing support in our application for a DCO and in the subsequent invitations to tender.”
Alwyn Hanekom, director of Power for MSPS, says the project is exceptional in scope and delivery: “Our initial appointment recognised our technical ability and innovative approach that challenges what the industry considers to be the norm. A project of this nature requires a significant level of multidiscipline experience, expertise and attention to detail, and will set the precedent for all future cable tunnel projects.”
Professor Colin Eddie, managing director of UnPS, says: “We believe we have been able to add real value and influence to the process. Our rich heritage and industry-leading experience in major tunnelling projects has ensured our accomplished design engineers have provided the most realistic and buildable solution to our customer.”
Together, MSPS and UnPS are currently finalising all aspects of the tunnel and shaft design, islet, and head house development together with its associated mechanical, electrical, civil and structural infrastructure works. In addition, the HV cable system and installation proposals will be developed working collaboratively with National Grid.
Further specialist services including marine and environmental engineering, planning, architectural design, third party engagement and transportation management are also being provided as part of the scope.