National Grid has resumed installation of the landfall cable that connects Block Island to mainland Rhode Island. The process is expected to be complete this winter.
The submarine cables were originally installed in the spring/summer of 2016 and subsequently experienced challenges with sediment coverage over the cables. After extensive due diligence, teams from Ørsted and National Grid determined the best approach to maintain proper burial depths of the two transmission cables is to reinstall these limited segments of the cables with new sections adjacent to where the existing cables now sit using a method called horizontal directional drill (HDD), a common procedure for submarine cables such as these.
The HDD will bury the cables at a depth of between 25 to 50 feet below the seafloor, as compared with the current 4 to 6 feet. This is 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 that connects the Island, the wind project and the mainland.
During the National Grid cable outage, Block Island Power Company (BIPCo) will provide the needed electrical power to the Island utilizing its on-island diesel generation.
National Grid and Ørsted have worked in close collaboration with the Town of New Shoreham, the Rhode Island Coastal Resources Management Council, Rhode Island Department of Environmental Management, the U.S. Army Corps of Engineers, and other key agencies to receive the necessary work permits and to keep stakeholders informed of the plans.