WorldWide Drilling Resource

26 DECEMBER 2020 WorldWide Drilling Resource ® Nation’s First Offshore Wind Farm to use Directional Drilling Adapted from Information by National Grid National Grid and Ørsted have started mobilizing teams to work throughout this winter to replace limited segments of the Block Island Wind Farm and sea2shore transmission cables to achieve greater burial depths beneath the ocean floor. The effort includes replacing approximately 1700 feet of National Grid’s sea2shore submarine cable which carries electricity between Block Island and mainland Rhode Island, and approximately 3100 feet of Ørsted’s submarine cable carrying electricity from the Block Island Wind Farm to Block Island. The submarine cables were originally installed in the spring/summer of 2016. Since then, the cables have had problems with sediment coverage over the cables. After extensive due diligence, teams from Ørsted and National Grid determined the best approach is to reinstall these segments of the cables with new sections adjacent to where the existing cables sit now. Teams for both National Grid and Ørsted are staging equipment and barges to be used on the project. The cable landings will be constructed using horizontal directional drilling (HDD), a common procedure for submarine cables such as these, and a conduit will be installed for the new length of onshore cable, including a new access pit. “We’re confident in the solution we’ve developed to ensure the Block Island Wind Farm transmission cable remains buried deeply below the ocean floor,” said Mikkel Mæhlisen, head of operations, Ørsted North America, Offshore. HDD will bury the cables at a depth of 25-50 feet below the seafloor, compared with the current 4-6 feet. This should be deep enough to withstand changing ocean floor conditions and provide a continued reliable interconnection for Block Island and the Block Island Wind Farm for years to come. The new cables will be spliced onto the existing cable connecting the Island, the wind project, and the mainland. The existing portions of the exposed cables are scheduled to be removed at the end of construction. Block Island and Rhode Island will continue receiving electricity from the wind farm during construction, except for a brief outage in the spring, when the new cable will be spliced with the existing cable. Construction is expected to be completed before Memorial Day 2021. “As the first offshore wind farm in the nation, the Block Island Wind Farm remains an enormous source of pride for all of Rhode Island,” said Terry Sobolewski, president of National Grid Rhode Island. “Both National Grid and Ørsted have been working rigorously with the town and state and federal partners on an enduring plan to address burial depth, and even amidst the pandemic, we are on track to having it completed in time for next summer.” DIR

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