“Any Other Purpose” Means Any: Subpart R Allows Case-by-Case Approval of Phosphogypsum Road Projects, and Preamble Language Cannot Override Unambiguous Regulatory Text

I. Introduction

In Center for Biological Diversity v. U.S. Environmental Protection Agency (11th Cir. Aug. 12, 2026), the Center for Biological Diversity (the “Center”) petitioned for review of EPA’s Notice of Approval for Other Use of Phosphogypsum, which authorized intervenor Mosaic Fertilizer, LLC (“Mosaic”) to use phosphogypsum—a radioactive byproduct of phosphate fertilizer production— in a small, private, on-site road “pilot project” at Mosaic’s New Wales Facility in Polk County, Florida.

The dispute arose under EPA’s radionuclide NESHAP regulations governing phosphogypsum (40 C.F.R. pt. 61, subpt. R). While Subpart R generally confines phosphogypsum to stack or mine disposal, it also allows EPA to approve distribution/use for “any purpose not expressly specified” in the categorical-use sections, via case-by-case approval under 40 C.F.R. § 61.206.

The Center raised two core merits challenges: (1) that Subpart R (read alongside the 1992 rule preamble) categorically forbids phosphogypsum road construction, and (2) that EPA’s approval was arbitrary and capricious under the APA because of allegedly flawed risk modeling (exposure durations, omitted exposure pathways, and reliance on older Ra-226 sampling). EPA and Mosaic also pressed threshold defenses—lack of associational standing and mootness based on project completion.

II. Summary of the Opinion

  • Jurisdiction: The Eleventh Circuit held the Center had associational standing (via member Michael Lexner) and that the case was not moot despite completion of phosphogypsum placement, because vacatur/remand could still yield meaningful relief (e.g., changed monitoring, remediation, or even removal).
  • Regulatory compliance: The court held Subpart R unambiguously permits EPA to approve phosphogypsum use for “any other purpose” under § 61.206; Subpart R does not categorically bar road projects and the 1992 preamble cannot override unambiguous regulatory text.
  • Risk-threshold dispute: Even assuming EPA used an incorrect benchmark (3 in 10,000 rather than the Center’s argued 9 in 100,000), any error was harmless because EPA’s modeled risks were far below both thresholds.
  • APA review: EPA’s technical methodology was reasoned, tailored to the pilot project, and adequately explained; EPA’s acceptance of older Ra-226 data was not arbitrary given conservative assumptions and conditions requiring updated sampling before construction.
  • Disposition: Petition denied.

III. Analysis

A. Precedents Cited

1. Standing and associational standing

The opinion’s standing analysis is rooted in the familiar Article III framework, framed as a jurisdictional prerequisite per Aguirre v. Seminole County (quoting Ex parte McCardle). The court reiterated standing’s centrality (citing Bischoff v. Osceola County and United States v. Hays) and its function (quoting Warth v. Seldin).

For organizational standing, the court applied Hunt v. Washington State Apple Advertising Commission, as reinforced in-circuit by Black Warrior Riverkeeper, Inc. v. U.S. Army Corps of Engineers. Only the first Hunt prong—whether a member has individual standing—was contested.

On injury in fact in environmental contexts, the court relied on:

  • Sierra Club v. Johnson (three-part test for injury, causation, redressability)
  • Sierra Club v. Tennessee Valley Auth. and Friends of the Earth, Inc. v. Laidlaw Env't Services (TOC), Inc. (aesthetic/recreational harms)
  • Parker v. Scrap Metal Processors, Inc. and Black Warrior Riverkeeper, Inc. v. U.S. Army Corps of Engineers (environmental health harms tied to members’ use/enjoyment)

Critically, the court emphasized that proximity to radioactive risk can constitute injury in fact, leaning on: Duke Power Co. v. Carolina Environmental Study Group, Inc. (even small non-natural radiation emissions can be direct injury), plus persuasive authorities including Texas v. Nuclear Regul. Comm'n (and its later reversal “on other grounds” in Nuclear Regul. Comm'n v. Texas), Nuclear Energy Inst., Inc. v. EPA, and Kelley v. Selin. These cases supported treating radiation-related exposure concerns and property-use impacts as sufficiently concrete and particularized.

On causation and redressability where government regulates a third party, the court applied Lujan v. Defs. of Wildlife (more demanding inquiry when injury depends on third-party action), but found causation satisfied because Mosaic could not legally proceed without EPA approval. For redressability, the court cited Harrell v. Fla. Bar (quoting Utah v. Evans) and clarified the temporal lens through Uzuegbunam v. Preczewski (standing asks whether redressability existed at filing).

2. Mootness

The court treated mootness as a distinct “strand” of jurisdiction (citing United States v. Ross), applying the Eleventh Circuit’s “meaningful relief” formulation from Sheely v. MRI Radiology Network, P.A. (quoting Toriano v. Supervisor of Elections), and reiterating the defendant’s heavy burden from Norwegian Cruise Line Holdings Ltd. v. State Surgeon Gen., Fla. Dep't of Health.

Mosaic’s mootness reliance on construction-completion cases (e.g., Knaust v. City of Kingston, Bayou Liberty Ass'n, Inc. v. U.S. Army Corps of Eng'rs, City of Romulus v. Wayne County, One Thousand Friends of Iowa v. Mineta, Neighborhood Transp. Network, Inc. v. Pena, and district precedent including Nat'l Parks Conservation Ass'n, Inc. v. U.S. Army Corps of Eng'rs (citing Save the Bay, Inc. v. U.S. Army and Fla.Wildlife Fed'n v. Goldschmidt)) failed because those plaintiffs sought only forward-looking injunctive or advisory declaratory relief.

Here, the requested relief—vacatur or remand of EPA’s approval—could still alter legal obligations and remediation options. The court analogized to Airport Neighbors All., Inc. v. United States, where even completed construction did not preclude relief affecting ongoing operations or requiring compliance steps.

3. Regulatory interpretation after Loper Bright and limits of preambles

On legal questions, the court invoked Loper Bright Enters. v. Raimondo for the proposition that courts decide “all relevant questions of law” under the APA, and that agency action inconsistent with law must be set aside. The court paired this with classic APA review principles from Citizens to Preserve Overton Park, Inc. v. Volpe (later “abrogated on other grounds” by Califano v. Sanders).

For deference to agency interpretations of their own regulations, the court applied Kisor v. Wilke: deference is available only if the regulation is “genuinely ambiguous,” a standard echoed in United States v. James and Hayes v. Dir., OWCP. It employed Rafferty v. Denny's, Inc. to emphasize the required “text, structure, history, and purpose” analysis before finding ambiguity.

The key interpretive move—refusing to let preamble language override unambiguous regulatory text—relied on: Gose v. Native Am. Servs. Corp. (plain meaning ends inquiry), Watkins v. City of Montgomery, Ala. (preambles can provide context), but especially Blanco v. Samuel (preambles do not have the force of law) (citing AT&T Corp. v. FCC), with additional support from other circuits such as Saint Francis Med. Ctr. v. Azar, Peabody Coal Co. v. Dir., Off. of Workers' Comp. Programs, and Peabody Twentymile Mining, LLC v. Sec'y of Lab..

To construe “any other purpose,” the court used the ordinary-meaning canon for “any” from Ali v. Fed. Bureau of Prisons, Encino Motorcars, LLC v. Navarro, and Harrison v. PPG Indus., Inc., and reinforced with Eleventh Circuit precedent Merritt v. Dillard Paper Co. and United States v. Castro.

4. Harmless error in administrative law

The panel applied administrative harmless-error doctrine, citing U.S. Steel Corp. v. EPA (a former Fifth Circuit decision binding via Bonner v. City of Prichard), along with Nat'l Ass'n of Home Builders v. Defs. of Wildlife and Shinseki v. Sanders. It distinguished U.S. Steel Corp. v. EPA because that case involved a notice-and-comment deprivation, whereas here any alleged threshold misselection did not affect outcome.

5. Arbitrary-and-capricious review and technical deference

The court applied the familiar Motor Vehicle Mfrs. Ass'n v. State Farm Mut. Auto. Ins. Co. framework, as stated in-circuit through BBX Capital v. FDIC (quoting Miccosukee Tribe of Indians of Fla. v. United States), and noted heightened explanatory obligations in public-health decisions per Am. Lung Ass'n v. EPA.

On scientific/technical judgments, the court emphasized “extremely deferential” review from Miami-Dade County v. EPA (quoting New York v. Reilly) and upheld EPA’s methodological choices as long as appropriate and reasoned.

Finally, on the non-binding nature of guidance, the panel cited Lewis v. City of Union City, Ga., Nat'l Mining Ass'n v. Sec'y of Lab., and Ryder Truck Lines, Inc. v. United States to confirm that EPA’s 2005 Workbook did not create enforceable obligations.

B. Legal Reasoning

1. Standing: proximity, ongoing property-use impacts, and incremental risk suffice at the pleading stage

The court credited Lexner’s sworn declaration describing curtailed use of his property (gardening, raising horses, well-water consumption), his proximity (under five miles), and his claim that the Road Project would add an additional phosphogypsum-related pollution source. The panel treated these asserted harms—health risk, diminished enjoyment of property, and related economic impacts—as concrete and particularized. It also accepted the “incremental” theory of injury: that the road could exacerbate an already-existing exposure concern.

On causation and redressability, the decisive fact was regulatory gatekeeping: Subpart R makes EPA approval a legal prerequisite. Therefore, vacatur/remand could prevent or delay the project (at filing), satisfying redressability under Uzuegbunam v. Preczewski.

2. Mootness: completion of construction does not moot a petition seeking vacatur/remand when ongoing obligations and remedial options remain

The court refused to treat physical completion as dispositive. Because EPA’s approval imposed continuing monitoring and could support additional measures, the court found “meaningful relief” remained possible—ranging from changed monitoring to capping or removal—so the case stayed live.

3. Subpart R interpretation: the regulation, not the preamble, is the law; “any” includes roads

The Center’s principal textual move was to use the 1992 preamble’s risk discussion to convert the rule into an across-the-board road ban. The court rejected that approach as a matter of administrative law: a preamble may inform, but cannot override unambiguous regulatory text.

Applying ordinary meaning, the panel held § 61.206’s “any other purpose” unambiguously covers road construction (indeed, any use not categorically authorized), so long as EPA finds the proposal “at least as protective” as stack/mine disposal. Because the regulation itself does not enumerate forbidden “other purposes,” the court refused to read in a categorical exclusion from preamble language describing only “the road construction scenarios analyzed” in 1992.

4. Risk threshold dispute resolved by harmless error

The panel did not need to definitively decide whether § 61.206(c)’s “at least as protective” standard necessarily imports the 1989 stack/mine risk number (9 x 10-5) or whether EPA may use a 1992-era 3-in-10,000 benchmark for “other uses.” It held instead that any threshold error was harmless because EPA’s modeled risks were orders of magnitude below both benchmarks.

This part of the opinion functions as a practical constraint on procedural challenges to risk benchmarks: where the record shows the same decision is inevitable under either standard, the court will not require a pointless remand.

5. APA merits: EPA’s risk modeling choices were reasoned, conservative, and appropriately scoped to a private pilot project

The court deferred to EPA’s technical judgments under Miami-Dade County v. EPA, emphasizing that the APA does not require “the single best methodology.” It upheld:

  • Exposure durations (one-month construction/transport; 250 hours/year road use; ~30-year residential exposure) as explained and aligned with project realities and prior modeling choices.
  • Omitting the reclaimer scenario because the road sits within an active industrial facility already adjacent to a phosphogypsum stack; redevelopment would require broader site remediation, making a “road-only reclaimer” scenario non-probative for this location.
  • Accepting older Ra-226 samples because the 2005 Workbook is non-binding guidance, § 61.207 requires updated sampling before removal/distribution, and EPA used conservative assumptions (roughly doubling Mosaic’s reported Ra-226) and imposed conditions requiring further sampling before construction.

The court also rejected the Center’s broader “taint” theory—that this pilot approval would improperly predicate future widespread approvals—because EPA expressly limited its analysis to this site and required independent future approvals.

C. Impact

  • Subpart R “other use” approvals are text-driven: The decision strengthens the principle that when a regulation’s operative text is clear, courts will not allow preamble statements to add categorical prohibitions absent regulatory language. This may matter beyond phosphogypsum, especially for regulated industries facing preamble-based arguments about implicit prohibitions.
  • Post-construction challenges may remain live: The mootness holding signals that regulated entities cannot automatically moot petitions by completing construction where agency approvals impose continuing obligations or where remedial relief remains plausible.
  • Harmless error as a limiting doctrine in risk-threshold fights: Petitioners challenging EPA’s choice of benchmark must confront the possibility that very low modeled risks will make the dispute outcome-determinative only in marginal cases.
  • Deference in technical modeling persists (within APA bounds): Even after Loper Bright Enters. v. Raimondo (courts decide legal questions), the opinion illustrates that factual/scientific judgments still receive substantial deference under arbitrary-and-capricious review.
  • Guidance documents remain non-binding: The treatment of the 2005 Workbook reinforces a recurring administrative-law boundary: regulated parties and challengers alike should not treat guidance as enforceable law unless incorporated into binding text.

IV. Complex Concepts Simplified

  • Phosphogypsum: A large-volume byproduct from phosphate fertilizer production that contains radionuclides (including Ra-226) and can emit radon gas.
  • Radon / radionuclides: Radon is a radioactive gas linked to lung cancer. Radionuclides are radioactive atoms that decay, emitting radiation.
  • NESHAP / Clean Air Act § 112: A Clean Air Act program requiring EPA to list hazardous air pollutants and set standards for source categories.
  • Subpart R baseline rule + exceptions: The default is stack/mine disposal; limited categorical uses exist (agriculture, research), and everything else requires case-by-case “other use” approval under § 61.206.
  • Preamble vs. regulatory text: The preamble explains a rule but generally is not itself legally binding; the codified regulatory text is.
  • Maximum Individual Risk (MIR): A modeled estimate of the increased lifetime cancer risk for the single most exposed person under a scenario.
  • Arbitrary and capricious review: Courts ask whether the agency explained itself rationally and considered important aspects—not whether the court would make the same technical choices.
  • Harmless error: Even if an agency makes a legal mistake, a court may affirm if the mistake could not have affected the outcome on this record.

V. Conclusion

Center for Biological Diversity v. U.S. Environmental Protection Agency confirms that Subpart R’s “other use” pathway means what it says: absent genuine textual ambiguity, EPA may approve phosphogypsum distribution/use for “any other purpose” (including a road project) if it satisfies § 61.206(c)’s protectiveness standard. The decision also underscores two practical administrative-law lessons: (1) completion of a project does not necessarily moot petitions seeking vacatur/remand where ongoing obligations and remedial relief remain possible, and (2) technical risk-modeling disputes will often rise or fall on whether the agency’s assumptions are explained, conservative, and tailored to the project—especially where any alleged benchmark error is harmless given the modeled risk magnitudes.