Geological Model for Menai Strait Tunnel

A 400 kV electricity transmission line is required to cross the Menai Strait to connect the proposed Wylfa Newydd Nuclear Power Station on Ynys Mon (also known as Anglesey) with the mainland. Through an initial feasibility study, the preferred Menai Strait crossing option requires the construction of a tunnel. The region has a complex geological history, where the oldest strata are interpreted as pre-Cambrian, comprising schist and tuff deposits. There are also Carboniferous bedrocks of interbedded limestones, mudstones and sandstones, and Ordovician siltstones and quartzite sandstones. The superficial deposits and landforms are understood to be almost entirely the signature of the last Devensian glaciation except for the occasional deposits and landforms which resulted from sea level fluctuation. Utilizing published geological records and project specific surveys, which include field surveys, rock exposure mapping, ground investigation and geophysical surveys, a 3D geological model has been created. This allows visualization of the anticipated geology of the area, identification of geological hazards and efficient design and planning for construction.