HDD to rehabilitate offshore wind farm

Orsted plans to rebury the exposed portions of its Block Island Wind Farm’s cable and transmission lines in Rhode Island, US.

According to the Providence Journal, the Block Island Wind Farm will have to go offline later this year to rebury a cable.

The wind farm’s electric cables were originally buried in trenches below the seabed; however, workers couldn’t get as far down as anticipated and over the past four years, waves and rough conditions have left portions exposed.  

Orsted now plans to rebury its cable in September this year, aiming to complete the entirety of works at Crescent Beach in the off-season and finalise the project by 25 May 2021.

Rhode Island Coastal Resources Management Council Executive Director Grover Fugate says the problems with the cables are attributed to the technology used to bury them along with natural forces.

“The area that they’re in is a very dynamic area — a lot of waves, a lot of sediment movement — so there’s a lot of potential for uncovering the cables,” said Mr Fugate.

“The complexity of the environment that they’re in is a mixture of sand, boulders, cobbles, those types of things, and not really conducive to the technology that they ended up using.”

Orsted’s cable runs from the wind farm to the island, while a second cable connects the island to the mainland electric grid and is owned by National Grid – who were originally advised by the coastal council to use HDD in the rough environment.

Orsted will employ the council’s advice and use HDD to replace the exposed section of its cable and bury it between 10-30 ft (3-9.1 m) beneath the sea floor.

“We are working together with National Grid and Block Island Power Company to limit the amount of time that the Block Island Wind Farm will need to be offline to accommodate this work,” said Orsted.

Providence Journal says that National Grid is also working on plans to rebury its own cable although the company has yet to release public details.

For more information visit the Orsted website.

If you have project news you would like featured in Trenchless International contact Head of Production Chloe Jenkins at cjenkins@gs-press.com.au

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