Technical design for Morecambe Bay cable tunnel 12 Jan 2017

In a first-of-its-kind engineering project to provide a 22km cable tunnel under Morecambe Bay for the National Grid, Morgan Sindall Professional Services (MSPS) and its sister business Underground Professional Services (UnPS) are near to completing the front end engineering design of 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 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 part of the North West Coast Connection which plans 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 seabed, between Barrow in Furness and Heysham.

The tunnel of about 5m diameter will house two 400kW cable circuits.. Due to strict ventilation requirements, and to ensure the high voltage cables do not overheat when fully loaded, an islet in the middle of the bay is proposed as a ventilation point and emergency escape.

Tunnel will house electricity cables from proposed Moorside nuclear power station

“This project requires various bespoke tunnel construction methodologies and lining designs, an understanding of marine works, and the associated challenges from both the cable installation and operational point of view, all with safety at the forefront,” said Neil Lyons, National Grid Senior Project Manager. “The MSPS and UnPS team has supported us from the outset, adapting designs with multiple options to satisfy different stakeholder groups, and completing the reference design within a tight timeframe. We now look forward to their continuing support in our application for a consent order and in the subsequent invitations to tender.”

“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,” said Alwyn Hanekom, Director of Power for MSPS. “It will set a precedent for all future cable tunnel projects.”

“We have added value and influence to the process,”” said Colin Eddie, Managing Director of UnPS. “Our expertise has provided the most realistic and buildable solution for this complex tunnel project.”

MSPS and UnPS are finalising all aspects of the tunnel and shaft design, of the islet, and of the head house development and its associated mechanical, electrical, civil and structural infrastructure works. The HV cable system and installation proposals will be developed working collaboratively with National Grid.

Further services provided by MSPS and UnPS include marine and environmental engineering, planning, architectural design, third party engagement and transportation management as part of the engagement scope.