With all permits expected to be issued before August, a tightly scheduled project to replace power lines running 11 miles along the bottom of Long Island Sound will begin before April. The seven existing self-contained fluid-filled cables have rested on the seabed since 1969 and are subject to damage from anchor drags and digging by shell fisherman, occasionally spilling insulating fluid into the sound.

Crews will replace the old lines with three cross-linked polyethylene (XPLE) cables buried at least 6 ft. under the seabed without any loss in the system's 138-kV capability. "Marine work is scheduled to start in October after the cables are decommissioned in September," says Jeff Martin, the Long Island Replacement Cable project manager for Northeast Utilities, Berlin, Conn. It awarded a $129-million engineer-procure-construct contract to Nexans, Olso, Norway, in June 2006. The permitting by the U.S. Army Corps of Engineers and various Connecticut and New York state agencies should be finished by the end of July, to be followed by the decommissioning of cables, Martin says.

The cables will be raised from barges in October, and the utility expects little resistance. "The lines are just lying on the floor of the sound in areas that are deeper than 35 ft," says Martin. Installation of the new cables is scheduled to begin in January and last six to eight weeks, says Martin. Crews will use remotely operated vehicles to inject water into the seabed, allowing the cables to sink to the desired depth, he says.

The XLPE cable system will likely transfer power between Northport, N.Y., and Norwalk, Conn., due to the price differences across the sound, says Richard Bolbrock, executive vice president-power markets for the Long Island Power Association.