## Facts

- EPA promulgated two final rules regulating emissions from “small” municipal waste combustion (MWC) units under Clean Air Act (CAA) § 129: emission guidelines for existing units and new source performance standards for new units.
- EPA used size-based subcategories (including “small” units) to set standards intended to reflect MACT-style limits for solid waste incineration units.
- Industry petitioners operating small MWC units sought review, arguing EPA committed procedural violations under CAA § 307(d), including inadequate explanation in the rule docket for size classifications and other key technical choices.
- Environmental petitioners sought review, contending parts of the standards were substantively too lenient under CAA § 129’s requirement that limits reflect the performance of the best-controlled units.
- Petitions for review were filed directly in the D.C. Circuit under CAA § 307(b).

## Issues

1. Whether EPA violated CAA § 307(d) by failing to include in the rulemaking docket an adequate statement of basis and purpose and by relying on rationales dispersed across other dockets and earlier, nonfinal materials.
2. Whether challenged emission limits and related regulatory choices complied with CAA § 129’s requirement that standards reflect the maximum achievable reductions, considering statutory factors.
3. What remedy was appropriate for any deficiencies (vacatur versus remand, and whether relief should be limited to particular portions).

## Decision

- The court granted the petitions in part and denied them in part.
- The court held EPA did not satisfy CAA § 307(d)’s requirement of a coherent statement of basis and purpose in the docket for the challenged rules, particularly as to key rationales such as size classifications.
- The court rejected certain substantive challenges where the record and explanation were sufficient and EPA’s technical judgments were supportable.
- The court remanded the rules to EPA in relevant part to cure the procedural deficiencies and revisit affected aspects as necessary, rather than setting aside the entire regulatory program.

## Legal Principles

- Under CAA § 307(d), EPA must place in the rulemaking docket for the rule at issue a statement of basis and purpose summarizing the rule’s factual foundations, analytical methodology, and major legal and policy rationales.
- EPA cannot satisfy § 307(d) by relying primarily on cross-references to rationales scattered across other rulemaking dockets or earlier, nonadopted proposals when the current docket does not itself provide a coherent explanation.
- Meaningful notice-and-comment and judicial review depend on an accessible, rule-specific administrative record that discloses the agency’s reasoning.
- Courts generally defer to EPA’s technical judgments under CAA § 129 when the agency’s reasoning and record support the choices; procedural failures that obscure the basis for the rule can require remand.

## Conclusion

The D.C. Circuit held that EPA’s small MWC rules were procedurally defective in part because the rule docket lacked an adequate, self-contained statement explaining critical rationales as required by CAA § 307(d), and it remanded the affected portions to EPA while otherwise upholding certain aspects against substantive challenges.


Northeast Md. Waste Disposal Auth. v. EPA, 358 F.3d 936 (D.C. Cir. 2004)