Two giant barges will arrive near Hempstead Harbor this weekend to begin round-the-clock repairs on a power cable damaged by an anchor in January.

The barges, one measuring 180 feet long, the other 120 feet, will be lighted all night, working about 2 miles from the nearest shoreline. Repair crews of 15 to 25 workers will put in 12-hour shifts to complete the work sometime in July, according to the New York Power Authority, which owns the cable that supplies power under contract to the Long Island Power Authority.

No materials will be stored on land to service the repair, but boats will shuttle crews to and from the barges during the course of the repair, a NYPA spokesman said.

NYPA said it has alerted local authorities, yacht clubs, marinas, harbor officials and others of the presence of the barges, which will lift the damaged cable from the water to splice on a new section of cable.

Leakage of nontoxic fluid from the cables was stopped early in the repair, NYPA said, and none is expected to be released as a result of the permanent repair work.

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The cable was damaged by a vessel setting its anchor in January. NYPA is suing the vessel owner, Melville-based Bouchard Transportation Co., in federal court to recoup costs, which are expected to exceed $30 million, NYPA has said in court papers.

NYPA owns and operates the 693-megawatt Long Island Sound Transmission Cable under contract to LIPA. A backup cable that went into service shortly after the accident has restored full capacity, NYPA said.

LIPA as the primary user of the cable is responsible for repairs and maintenance, according to PSEG Long Island, which operates the grid. PSEG ratepayers will pick up any costs not recouped by NYPA through insurance or litigation, NYPA said.

The 23-mile cable connects Long Island to the upstate grid.