## Facts

- Subtitle C of the Resource Conservation and Recovery Act (RCRA) regulates hazardous waste treatment, storage, and disposal; the 1984 amendments emphasized treatment over land disposal.
- RCRA § 3004(m) directs EPA to set treatment levels or methods that substantially reduce toxicity or the likelihood of migration of hazardous constituents.
- “Spent potliner” (K088), a hazardous byproduct of primary aluminum production containing cyanides and other constituents, was subject to EPA rules under RCRA § 3004.
- EPA issued three related rules for K088: (1) a numeric treatment standard, (2) a prohibition on land disposal of untreated K088, and (3) a national capacity variance delaying the prohibition’s effective date.
- EPA used the Toxicity Characteristic Leaching Procedure (TCLP) to determine compliance with the K088 treatment standard, relying heavily on treated K088 from Reynolds Metals Company’s full-scale process and TCLP results from that material.
- After promulgation, EPA sampled leachate from Reynolds’s dedicated landfill and found hazardous constituent concentrations significantly higher than the TCLP simulation and exceeding the new treatment standard’s limits.
- EPA attributed the discrepancy to alkaline conditions in the actual landfill (as compared to the TCLP’s assumed conditions) but left the TCLP-based compliance test in place, reasoning the standard still improved prior practices.
- Aluminum manufacturers petitioned for review, challenging the TCLP-based compliance test as arbitrary and capricious and raising additional challenges to the land-disposal prohibition and capacity variance.

## Issues

1. Whether EPA acted arbitrarily and capriciously by using TCLP as the compliance test for the K088 treatment standard despite field data showing TCLP did not predict actual landfill leachate concentrations for K088.
2. Whether EPA’s related land-disposal prohibition for untreated K088 and the national capacity variance were lawful under RCRA § 3004.

## Decision

- The court vacated and remanded EPA’s test for determining compliance with the K088 treatment standard because it was arbitrary and capricious under the Administrative Procedure Act.
- The court denied the petitions for review in all other respects, leaving the remainder of the K088 regulatory scheme (including the land-disposal prohibition and national capacity variance) in effect.

## Legal Principles

- Under arbitrary-and-capricious review, an agency must examine the relevant data and provide a satisfactory explanation establishing a rational connection between the facts found and the choice made.
- When an agency’s own evidence shows that a chosen compliance test fails to predict real-world performance in the specific regulated setting, continued reliance on that test requires a reasoned reconciliation; otherwise the test may be set aside as arbitrary and capricious.
- A court may tailor relief by vacating and remanding the unlawful component of a rule while upholding other provisions that are adequately justified and within statutory authority.

## Conclusion

The D.C. Circuit held that EPA could not continue to use TCLP as the compliance test for the K088 treatment standard after EPA’s own monitoring showed TCLP materially understated actual leachate concentrations in a dedicated K088 landfill; it vacated and remanded that compliance-test component while sustaining the remaining RCRA land-disposal measures and the temporary capacity variance.


Columbia Falls Aluminum Co. v. EPA, 139 F.3d 914 (D.C. Cir. 1998)