A unique cable burial that combines innovative technology with natural ecological protection

Scylla is the subsea cable system that forms part of our Super Highway fibre network between London and Amsterdam. It is a state-of-the-art, high capacity fibre system delivers ultra-low attenuation over 211 km, unrepeated, between cable landing stations.

Uniquely buried

What makes Scylla particularly unique is the way it was buried. The North Sea is a notoriously hostile environment for subsea cables due to a combination of high water currents, a mobile, sandy seabed, and intense fishing that present regular service challenges to traditionally laid cables due to cable strikes and fibre cuts.

Scylla was laid using a jetted micro-routing burial approach, and is the only sea cable in the North Sea buried this way. Micro-routing follows the contours of the sea bed to lay the cable at their deepest point, with predicted sand wave movement further burying the cable over time. 

The jet itself buried the cable up to three metres deep along the micro-routed path, and in combination achieved the most secure cable burial available in this region, mitigating against strikes today and in the future.

Surveying Scylla

Two years on from its deployment, a recent burial survey on the inshore and offshore sections of Scylla shows that the predicted sand wave movement has increased the cables’ already impressive average burial depth of between 2-3 metres, compared to 0.5-1.5 metres achieved by traditional methods. This further enhances the systems resilience in a North Sea environment that is notoriously hostile and prone to cable strikes.

Carrying out surveys like this on buried cables isn’t common among operators. But by surveying regularly we have ongoing visibility of burial depth across the cable lay, and the dynamic movement of the area’s sand wave environment. This proactively highlights areas of risk, rather than reacting to cable strikes after the fact. 

Scylla’s burial is just one example of the innovations that make Super Highways unique.

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