Chemical maker Hercules will pay $11.3 million toward cleanup of a Superfund site in Gloucester County under a consent decree reached in federal court with the U.S. Environmental Protection Agency and the state of New Jersey that would require tons of toxic soil to be dug up and removed.

“The DEP is pleased that Hercules has agreed to reimburse the state for all outstanding costs to the state for the remediation of the Gibbstown plant, and to complete the remediation of the site," Catherine R. McCabe, commissioner of the state Department of Environmental Protection, said in a statement. "Hercules' assumption of responsibility for long-term monitoring of the remaining soil and groundwater contamination will ensure that the public and the environment are protected.”

The 350-acre Hercules Inc. site in Greenwich Township contains a portion of Clonmell Creek that flows toward the Delaware River and separates an 80-acre former plant and a four-acre solid waste disposal area.

Hercules purchase the site in 1952 from DuPont, which the EPA said disposed of lead fragments and tar produced while making the chemical compound aniline. Hercules then used a portion of the site to make phenol and acetone.

The use over decades resulted in contamination of soil and groundwater with volatile organic compounds and heavy metals. As a result, sediment in Clonmell Creek was also polluted.

The Gibbstown site was listed as a Superfund site in 1983. The plant was decommissioned and demolished in 2010. The EPA announced a cleanup plan in 2018.

“This important agreement ensures that the responsible party will perform the work needed to address contamination at the Gibbstown Plant,” EPA Regional Administrator Pete Lopez said.

Under the consent decree, Hercules must implement the EPA’s 2018 plan and the agency will oversee the work.

In addition, the company must also pay $144,000 in other costs to the EPA and $130,000 to New Jersey.

The plan requires Hercules to excavate four feet of contaminated soil and treat it with microorganisms to break down contaminants. Deeper soil will also be treated to encourage microorganisms to destroy the remaining chemicals. Cleaned soil will be used as a cap.

Further, Hercules will have to dig up lead-contaminated soil and dispose of it off-site, and remove contaminated sediment from the creek and a stormwater basin.

A groundwater extraction and treatment system has already been installed to protect local municipal drinking water wells. To date, more than two billion gallons of contaminated groundwater have been treated.Hercules was one of 14 Superfund sites in the Philadelphia region identified by The Inquirer as lying within a flood zone susceptible to rising seas connected with climate change. In the event of a flood, such sites have the potential to spread contaminants.

The consent decree is subject to a 60-day public comment period and final approval by U.S. District Court in Camden.

The New Jersey Sierra Club hailed the agreement as a win.

“Finally, Hercules will be paying to clean up the mess they made," said the group’s director, Jeff Tittel.

But, he said that Hercules was getting off “cheap” and said the EPA failed to order a “full cleanup” that includes a long-term plan to remove tar pits at the site, as well as additional soil and water.