National Grid has called for contractors to express interest in works on a pipeline of major cable tunnel projects including a £100M tunnel under the Menai Strait and a 33km power tunnel line in south London.
The project pipeline includes the 4km Menai Tunnel, which was described as one of the most significant civil engineering project in Wales, to connect the proposed Wylfa Newydd nuclear power station on Anglesey to the main grid. Construction of the tunnel is expected to take five years.
Another project in the pipeline is the 33km London Power Tunnels second phase, which will run from Wimbledon in south-west London to Crayford in south-east London, and is expected to begin in summer next year.
The first phase of the power tunnels project – a £1bn, 32km long tunnel running from Hackney in east London to Willesden to the west of the capital, and from Kensal Green in the north-west to Wimbledon in the south - was completed in February this year. Two new substations were also built as part of the scheme.
Work on the 3.3m Snowdonia visual impact provision project, which is also in North Wales, is included in the project pipeline. The existing overhead line will be replaced with underground cabling to reduce the visual impact of the infrastructure.
The early engagement exercise (EME) will seek advice from potential supply chain partners to plan the procurement process for the works.
National Grid is accepting expressions of interest from contractors specialising in shaft, tunnelling, mechanical, electrical, tunnel ventilation, industrial building, high voltage cable and overhead line cable installation. The EME is also open to tunnel boring machine manufacturers, concrete segment manufacturers and supervisory control and data acquisition suppliers.