Block Island gets connected

To the mainland
Fri, 07/01/2016 - 11:45am
Category: 

After decades of discussion and proposals by various town officials, boards and councils, an undersea electric transmission cable linking Block Island to the mainland is now a reality.

On Thursday, June 23, National Grid landed its 30-megawatt sea2shore cable at the Fred Benson Town Beach to make the connection. National Grid then spliced its $107 million sea2shore cable with the terrestrial cable on Tuesday, June 28 at 5 p.m. 

After learning of the cable’s landing, Town Manager Nancy Dodge told The Block Island Times that, “It's such a historic moment to see this become a reality after all the years of talking about a cable to the mainland. Congratulations to all who made this engineering feat come to pass. And thanks to Mother Nature for giving us perfect weather.”

The cable installation is a component of Deepwater Wind’s Block Island Wind Farm pilot project, which will utilize the cable to deliver energy produced from the wind farm to island residents, as well as mainland ratepayers. It is not yet live; the Wind Farm is expected to begin operation some time later this year.

According to town officials, there is an ancillary yet necessary benefit of having an electrical link to the mainland: eight strands of fiber optic cable to build an island-wide broadband Internet network.

Deepwater Wind CEO Jeff Grybowski said, “Today marks another important milestone for the project, and we’re grateful not only to National Grid for their hard work but also to the Block Island community for their support during this installation. We’re looking ahead to a busy offshore construction season, and to powering the island by year’s end via this first-ever offshore wind transmission system.”

Of the installation, David Graves, National Grid's Media Relations Director, said, "The cable is landed and secured. We will have equipment off the beach and out of the parking lot on, or before, the June 30 deadline." National Grid spent the past week removing its equipment from the beach. The large cranes and excavators were picked up and the steel walls used to build two cofferdams were stacked in piles next to the Block Island Power Company.

For decades, an island-to-mainland cable system was something island officials have entertained to reduce fuel and energy costs and to eliminate the use of diesel-generated electricity on-island. The town’s energy plan from June 4, 2012 noted that the price tag of a mainland to island cable would cost an estimated $20 million to $45 million. Estimates from studies conducted by earlier island committees noted a $2 million to $5 million price tag for the cable. 

As for the cable installation process: on Thursday, June 23, National Grid landed its sea2shore submarine cable at Fred Benson Town Beach. That morning, the 20-mile long cable was cut from its spool on the cable-laying-barge Big Max and pulled ashore via a winch and a string of airbags. Once it landed at the beach, technicians guided the cable into the steel cofferdam, through a conduit (pipe) and under the sand dunes to a manhole located in the north parking lot on Corn Neck Road. 

In laying the cable, Big Max installed the cable six feet under the seabed through 20 miles of state and federal waters. On the morning of Friday, June 24, the jet plow, the piece of equipment that forges a trench in the seabed to lay the cable, installed the cable from the barge to the beach. Four days later, National Grid technicians began splicing the sea2shore submarine cable with the land cable in a manhole in the north parking lot.  

Deepwater Wind Project Manager Bryan Wilson explained that in splicing the submarine and terrestrial cables together, six copper conductors, three for National Grid’s cable and three for Deepwater Wind’s export cable, as well as bundles of fiber optic cables, were merged. The land-based terrestrial cable runs in duct-banks from the north parking lot at the beach, along Corn Neck Road and Beach Avenue, to BIPCo's Ocean Avenue property where two substations are being constructed.

Now, Deepwater Wind will begin gearing up for its offshore construction activity.

While National Grid continues to build the two substations, Deepwater Wind will be completing its export cable installation at the wind farm site. Then, in August, Deepwater Wind will begin installing its five six-megawatt 270-foot, 440-ton wind turbine towers and the 246-foot long GE Haliade 150 blades.

On Monday, June 27, all 15 of the wind turbine blades arrived from Denmark, passing under the Newport Bridge before being delivered to GE and Deepwater Wind's assembly facility at the Port of Providence. 

Deepwater Wind intends for the Block Island Wind Farm to be fully operational in the fall of 2016. The wind farm is situated in a high wind zone three miles off the southeast coast of Block Island.