Background
Mosaic Fertilizer sought EPA approval under 40 C.F.R. § 61.206 to use about 1,200 tons of phosphogypsum—a radioactive fertilizer-production byproduct—in a small-scale pilot road at its privately owned New Wales Facility in Polk County, Florida. The proposed road consisted of four test sections using different phosphogypsum concentrations. After reviewing the application, conducting a technical risk assessment, and receiving public comments, the EPA approved the project in December 2024, subject to sampling, groundwater monitoring, and other conditions.
The Center for Biological Diversity petitioned for direct review under the Clean Air Act. It argued that EPA regulations categorically barred phosphogypsum road construction, that the agency used the wrong cancer-risk threshold, and that its assessment was arbitrary and capricious because it used unduly short exposure periods, omitted a future-resident “reclaimer” scenario, and accepted radium-226 data more than three years old. The EPA and Mosaic disputed the Center’s associational standing; Mosaic alone also argued that completion of the phosphogypsum-containing road sections had mooted the case.
The Court’s Holding
The Eleventh Circuit held that it had jurisdiction. The Center established associational standing through a member who lived less than five miles from the facility and alleged that the project would exacerbate concrete health, property-use, recreational, and economic injuries. The case was not moot because vacatur or remand could still affect ongoing monitoring requirements and could potentially lead to additional measures such as capping or removing the road.
On the merits, the court held that § 61.206 unambiguously permits EPA to approve phosphogypsum for “any other purpose,” which includes road construction. The 1992 rulemaking preamble did not override that text or categorically prohibit all road uses. The court did not decide whether EPA should have used the Center’s proposed risk threshold of 9 in 100,000 rather than 3 in 10,000 because the project’s calculated risks fell well below both thresholds, making any error harmless.
The court also held that EPA’s approval was not arbitrary or capricious. EPA reasonably tailored exposure durations to this private pilot project, explained why a residential reclaimer scenario was implausible at an active industrial facility already containing phosphogypsum stacks, and conservatively modeled radium concentrations at more than twice Mosaic’s reported level. The agency’s 2005 workbook was nonbinding guidance, while the governing regulation required updated sampling before phosphogypsum was removed from the stack. The court therefore denied the petition for review.
Key Takeaways
- Section 61.206 allows EPA to approve phosphogypsum road construction on a case-by-case basis as an “other purpose”; the regulation does not impose a categorical road-use ban.
- Any dispute over EPA’s selected cancer-risk threshold was harmless because every calculated project risk was below both the agency’s threshold and the stricter threshold urged by the Center.
- EPA reasonably limited its scientific analysis to exposure pathways and durations corresponding to the specific private pilot project, and its nonbinding workbook did not create an enforceable requirement for sampling data from the preceding 12 months.
Why It Matters
The decision confirms that regulatory preambles and agency guidance cannot displace the unambiguous text of a regulation. It also illustrates the substantial deference courts give an agency’s explained technical and scientific judgments when reviewing agency action under the arbitrary-and-capricious standard.
The ruling is limited to Mosaic’s pilot road. EPA expressly stated that other phosphogypsum road projects would require separate applications, risk assessments, and approvals, so the decision does not categorically authorize broader use of phosphogypsum in road construction.