The time had come to replace 11 miles of worn, 40-year-old cable that runs underneath Long Island Sound between Northport, N.Y. and Norwalk, Conn.
The cables had supplied up to 300 megawatts of electric power to either New England or New York when needed. But the $140 million project, which began in the fall of 2007, was so complex that it required one of the most technologically advanced ships in the world and sensitivity to the environment that halted operations while piping birds mated and fishermen caught summer flounder.
Completed in the fall of 2008, the project was commissioned by Northeast Utilities and its subsidiary Connecticut Light & Power, both based in Berlin, Conn., with assistance from the Uniondale, N.Y.-based Long Island Power Authority. The challenge was to remove the old cables, which were leaking non-toxic fluids from years of being hit by anchors, and replace them with new advanced-designed cables that could be buried at least six feet below the seabed, eliminating the need for environmentally undesirable dredging.
Because the C/S Nexans Skagerrak, a Norwegian ship that could carry as much as 7,000 tons of cable, was only available for a limited amount of time, the month-long cable-laying operating ran 24 hours a day in February 2008. With slightly more than 36 miles in length needed for the project, the cable was unspooled over the waters of the sound and cut into three lengths of about 11.5 miles each.
At times, Fred J. Dymek, senior project manager with New York-based AECOM Energy, said crews faced storms so strong, “you thought you were on the ocean.”
But, he said, given the overall complexity and magnitude of the project: “If we didn’t have the total commitment and buy-in by the total team and organizations they represented, this would have been an impossibility. It took a lot of dedication on everyone’s part in order to get that done.”
During removal and installation operations, project team members worked closely with a local lobstermen’s associations on Long Island to aid in lobster trap relocation, removal and identification. In Norwalk, Conn., harbor officials and a local shellfish commission monitored the project for possible damage to oyster beds.
Said Jeffrey Martin, Northeast Utilities’ project manger for transmission business projects: “The overall success of the project demonstrates that with the state-of-the-art technology, high-voltage cables can be installed offshore over a long distance without negative effects on the environment and with positive benefits to the surrounding communities.”
Owner and Project Manager: Northeast Utilities/ Connecticut Light & Power, Berlin, Conn.
Co-Owner: Long Island Power Authority, Uniondale, N.Y.
Construction Oversight Services: AECOM/ENSR, of New York (Originally NU brought in DMJM Harris team, which was subsequently acquired by AECOM)
Environmental Consulting: ESS Group, East Providence, R.I.
Marine Contractor (Engineering, Procurement and Construction Contractor: Nexans, Paris
Marine Subcontractor: Durocher Marine, Cheboygan, Mich.
Marine Subcontractor: Caldwell Marine, Farmingdale, N.J.
Environmental Subcontractor: TRC Environmental, Lowell, Mass.