National Grid constructing cofferdam
A large sheet of steel was guided by construction personnel into the proper location and driven down into the sand by a red crane at the Fred Benson Town Beach on Wednesday, March 23.
The steel sheet is a component of the cofferdam; a watertight enclosure pumped dry to permit construction work below the waterline, and will be the conduit for National Grid’s 20-mile long sea2shore submarine cable, which will be laid 6-feet beneath the sea floor and come ashore at the Town Beach in May. Once it arrives from the mainland, the cable will be converted into a land cable, routed 10-feet underneath the dunes and parking lot to Corn Neck Road, where it will be encased within concrete and redirected through duct banks in the road for almost one-mile to the National Grid substation at the Block Island Power Company (BIPCo) on Ocean Avenue.
National Grid and one of its subcontractors, J.H. Lynch & Sons, Inc., whose personnel are residing on the island during the construction process, have been installing components of the cable transmission system at the Town Beach since February. Construction work has included activity at the Town Beach, on Corn Neck Road and Beach Avenue, and at BIPCo’s property on Ocean Avenue.
The transmission cable will have a capacity of 30-megawatts and transmit energy produced by the Deepwater Wind Block Island Wind Farm to the New England Power Company on the mainland.
National Grid's timeframe for on-island cable installation will run through the end of May. The Block Island Wind Farm is schedule to be operational in the fall of 2016.