The U.S. Environmental Protection Agency has finalized a new cleanup plan for the Vineland Chemical Company Superfund site in New Jersey, targeting arsenic contamination that has persisted despite more than $200 million in remediation spending since the early 1990s.

The Vineland Chemical Company produced arsenic-based herbicides and fungicides at the site from 1949 to 1994. According to the EPA, the company improperly stored arsenic salts in open piles, lagoons and chicken coops, releasing contamination across the surrounding area. The legacy pollution continues to affect groundwater, sediment and nearby floodplain soils. The newly finalized plan addresses a specific remaining source: arsenic in soil beneath the groundwater table.

"Finalizing this cleanup plan marks a critical step in addressing a vexing and persistent source of arsenic contamination at the Vineland Chemical site," EPA Regional Administrator Michael Martucci said in a statement. "EPA's plan directly targets that remaining source, builds on decades of cleanup progress, and will help protect human health and the environment for years to come."

What does the new plan involve?

The remediation design relies on several engineered interventions:

• Treatment of underground contaminated zones with air pumped into the ground to stabilize contamination
• Injection of iron-based materials into the subsurface to prevent arsenic from migrating
• Installation of a horizontal hydraulic barrier underground to stop arsenic from accumulating in floodplain soil and sediment
• Restoration of wetland areas that the cleanup work itself could disturb

The EPA said it will monitor the remediation process to verify effectiveness and continue evaluating the site after the work is complete.

Who pays, and how much has it cost?

The EPA placed the site on the federal Superfund National Priorities List in 1984 and has led cleanup work there since the early 1990s, spending more than $200 million to date. Under the federal Superfund law, New Jersey shares 10% of cleanup costs. The agency has also secured settlements exceeding $3 million with several responsible parties to help fund the work.

How is exposure being controlled?

Arsenic is linked to serious health effects, including some cancers. Drinking water in the area undergoes regular testing to confirm it meets state and federal standards. The EPA has also worked with New Jersey regulators to restrict well installation and other groundwater uses in the affected area.

The next milestone for the site is execution: the effectiveness of the iron injections, air treatment and hydraulic barrier will determine whether the decades-long groundwater and floodplain contamination at Vineland is finally contained.