NEWARK -- A $165 million agreement reached by the federal government with one of the companies potentially responsible for contaminating a stretch of the Passaic River will allow early stages of cleanup to begin on one of the nation's most polluted bodies of water, officials said.

The U.S. Environmental Protection Agency has negotiated a legal agreement with the Occidental Chemical Corporation to perform engineering and design work needed to begin the cleanup, a release from the EPA said. The work will take place in the lower 8.3 miles of the Passaic River, which runs from Newark Bay to the Newark/Belleville border.

OCC will spend $165 million, the release said, to create sampling and quality assurance plans, evaluate removal technologies, and carry out the engineering work necessary to move forward with the actual clean up.

The entire cleanup is estimated to cost about $1.38 billion, and OCC, while it won't be footing the entire bill, officials said, will not be immune to contributing additional funds toward the final amount.

"This is one of the largest cleanups to have taken place in the nation," said Judith Enck, regional administrator at the EPA, during a telephone press conference Wednesday.

To illustrate just how big of an undertaking the clean up will be, Enck said the amount of polluted sediment in the lower 8.3 miles of the Passaic, colloquially known as the "lower eight," could fill the Red Bull Arena in Harrison three times over.

The cleanup plan calls for sediment to be dewatered, transported by train for disposal, and the entire lower eight miles to be "capped," meaning a sand and stone barrier of about two feet will be laid above the contaminated sediment remaining after dredging.

While the EPA has identified more than 100 other companies that could be potentially responsible for the river's pollution, the release of dioxin, one of the most deadly toxins in the water, according to the agency, was caused by the former Diamond Alkali facility in Newark.

Diamond Alkali, later acquired by OCC in a corporate merger, produced Agent Orange and other pesticides during the 1960s, which generated dioxin that contaminated the land and river, the release said.

In a statement, Mayor Ras J. Baraka said the agreement reached by the EPA is another step in the Newark's long struggle to reclaim its Passaic waterfront.

"The clean up is still in its early stages, and much more needs to be done to completely remove the toxic residue from past industrial use of the River," Baraka said. "By cleaning up the Passaic and creating access to a beautiful waterfront of open space and parks, we are building the future of Newark."

The cleanup plan, the release said, requires the permanent removal of 100 chemicals, including about 24,000 pounds of mercury, 6,600 pounds of PCBs, 1,300 pounds of DDT, a pesticide, and 13 pounds of highly toxic dioxin.

The first stage of the clean up, which will be paid for and carried out by OCC, will take four years, Enck said. The actual dredging and capping of the river will take another six.

"The EPA will work to secure similar agreements with the other parties that polluted the Passaic River and have the legal responsibility to pay for the cleanup," Enck said. "We're dealing with over a century of pollution. We'll need a decade to clean it up."

Michael Anthony Adams may be reached at madams@njadvancemedia.com. Follow him on Twitter @MichaelAdams317. Find NJ.com on Facebook.