In a settlement with federal agencies, AVX Corp. has agreed to pay more than $366 million, an infusion that officials say will dramatically speed up the long-running cleanup of the PCB-contaminated New Bedford, Mass., harbor.

The Justice Dept. and Environmental Protection Agency say that the cash settlement, announced on Oct. 10, will be the largest ever for a single Superfund site, if approved by a federal court.

The agencies say the payment would enable the New Bedford harbor cleanup to be finished in about five to seven years, compared with 40 or more years at the current annual funding rate of $16.5 million from the Superfund and Massachusetts.

The project involves dredging sediment contaminated with PCBs—polychlorinated biphenyls—and depositing it in what officials call a “confined aquatic disposal cell” in the lower harbor and in other facilities to be constructed along the shore.

Wyn Hornbuckle, a Justice Dept. spokesman, says that cleanup work began at the New Bedford site in 1990, including a "hot spot" program that dealt with the highest concentration of PCBs. But he says "the bulk of the work" started in 2002, and adds that about $450 million had been spent on the project as of 2011.

From the late 1940s through the late 1970s, an Aerovox Corp. electrical-capacitor plant located on the northern end of the inner harbor discharged hazardous substances including PCBs, contaminating sediment, federal and state officials say.

The settlement follows an April 18 EPA administrative order directing AVX to carry out the rest of the harbor cleanup.

Justice and EPA say that AVX, based in Greenville, S.C., is the successor to Aerovox. In a statement, AVX referred to Aerovox as “an alleged legal predecessor.”

AVX also said: “Subsequent owners of the facility are dissolved or in bankruptcy.” The company said that the plant made liquid-filled capacitors and added, “AVX itself never produced this type of capacitor, nor does it do so today.”

Aerovox said it will pay out the $366 million, plus interest, in three installments over two years and that EPA would withdraw the April order. EPA and Justice say the payment would resolve AVX’s remaining cleanup responsibilities at the harbor site.

The settlement is contained in supplemental consent decree filed in U.S. District Court in Massachusetts on Oct. 10. It alters provisions of a 1992 harbor cleanup consent decree.

The deal is the latest chapter in a court proceeding that began in 1983, when the U.S. and Massachusetts filed a lawsuit against AVX and other companies alleging that PCB releases led to environmental harm in the harbor.

In 1992, AVX agreed to pay $72 million, including interest, for the cleanup but that agreement also had reopener provisions that allowed EPA to seek to have AVX carry out or finance additional cleanup work, under certain conditions.