TenneT selects Deep for annual Dutch offshore cable integrity surveys

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Dutch transmission system operator TenneT has selected Deep BV to carry out annual integrity surveys of its offshore cable infrastructure in the Netherlands from 2026 through 2029, strengthening monitoring of subsea assets as the North Sea power grid expands.

The contract covers hydrographic and geophysical surveys designed to measure seabed cover over existing cables and detect objects or seabed changes that could threaten cable integrity. Selected findings will undergo visual inspection when additional assessment is required.

No contract value has been disclosed. The award follows a TenneT procurement process for a multi year framework covering offshore geophysical surveys of cable routes and platform locations. That procurement carried an estimated total value of €41.75 million, although that figure should not be interpreted as the value of Deep’s individual assignment.

The surveys will give TenneT updated information on cable burial, seabed conditions and potential hazards along its offshore transmission routes. The resulting datasets will support maintenance planning, risk assessment and compliance with permit requirements.

For subsea power infrastructure, the seabed is not static. Currents and sediment movement can alter cable cover over time, while objects on or near a route can introduce additional risks. Regular surveys effectively provide TenneT with repeated snapshots of those changing conditions.

TenneT COO Maarten Abbenhuis said regular monitoring is becoming increasingly important as additional offshore wind farms and international interconnectors are connected to the high voltage network.

“Periodic surveys allow TenneT to assess conditions along its cable routes, monitor changes over time and identify potential risks, all to prevent outages,” Abbenhuis said.

Deep Commercial Director William Waggeveld said regular monitoring was an essential part of managing subsea infrastructure and that the contract would apply the company’s survey capabilities to assets supporting the Dutch renewable energy system.

The assignment extends Deep’s existing work around TenneT’s offshore network. Together with Next Geosolutions, Deep previously performed nearshore geophysical unexploded ordnance surveys supporting five of TenneT’s planned 2 GW offshore grid connections.

TenneT is simultaneously increasing the scale of its offshore monitoring requirements. Its wider survey procurement states that operational cable connections require surveys along subsea and land cable routes as well as around offshore platforms, with the collected information feeding directly into asset integrity management and compliance reporting.

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