EPA Settlement Could Reclassify Phosphogypsum as Hazardous Waste Under RCRA

What Happened

The EPA has published a proposed settlement agreement in the case In Re Center for Biological Diversity, et al. (D.C. Circuit, No. 25-1087), which could lead to a reclassification of phosphogypsum and phosphoric acid production process wastewater under federal hazardous waste law. The settlement, published in the Federal Register on February 26, 2026, resolves allegations that the EPA failed to act on a 2021 rulemaking petition within a reasonable timeframe.

The Center for Biological Diversity's petition sought to reverse EPA's 1991 Bevill regulatory determination that exempted phosphogypsum and associated process wastewater from Resource Conservation and Recovery Act (RCRA) hazardous waste regulations. Under the proposed settlement, EPA would be required to respond to the petition on a defined timeline.

What Is Phosphogypsum and Why Was It Exempted?

Phosphogypsum is a byproduct of the wet-acid process used to produce phosphoric acid from phosphate rock. For every ton of phosphoric acid produced, approximately five tons of phosphogypsum are generated. The material contains naturally occurring radium-226, uranium, and other radioactive elements concentrated from the original phosphate ore.

In 1991, EPA determined under the Bevill Amendment that phosphogypsum and phosphoric acid process wastewater did not warrant regulation as hazardous waste under RCRA Subtitle C. This determination allowed the phosphate industry to manage these materials under less restrictive state programs. An estimated 1 billion tons of phosphogypsum currently sit in stacks across Florida, Louisiana, and other phosphate-producing states.

Why It Matters for Chemical Operations

If EPA ultimately reverses the 1991 determination, the consequences would ripple through the phosphoric acid supply chain:

• Phosphoric acid producers could face new disposal, storage, and monitoring requirements for phosphogypsum stacks
• Transportation and logistics for phosphogypsum could require hazardous waste manifests and licensed haulers
• Downstream users of phosphoric acid — including food processing, water treatment, and fertilizer operations — may see cost increases passed through the supply chain
• Existing phosphogypsum stacks in Florida, Louisiana, Idaho, and North Carolina could be subject to RCRA corrective action requirements

The U.S. phosphate industry generates roughly 27 million metric tons of phosphogypsum a year as a by-product of phosphoric acid production, making this one of the highest-volume chemical processes that could be affected by a reclassification.

What to Watch

The public comment period closes March 30, 2026. The settlement itself does not mandate a specific outcome — it requires EPA to respond to the petition, which could mean granting it, denying it, or proposing a modified approach. However, the fact that EPA agreed to settle rather than continue litigation suggests the agency is prepared to revisit the 1991 determination.

Chemical buyers who rely on phosphoric acid should monitor this proceeding. Any reclassification would likely include a multi-year compliance timeline, but early awareness allows facilities to plan for potential supply chain and cost impacts.