## Facts

- Howmet Corporation used liquid potassium hydroxide (KOH) as a caustic cleaning solution in manufacturing to remove fats and oils from metal parts.
- Through use, the KOH became contaminated with oils, greases, dirt, and other residues and eventually could not function effectively as a cleaner without further processing.
- Instead of disposing of or regenerating the used KOH for continued cleaning, Howmet shipped tanks of the used solution to a fertilizer manufacturer, which blended it into fertilizer applied to land.
- EPA initiated an administrative enforcement action alleging Howmet failed to manage and ship the used KOH as hazardous waste under the Resource Conservation and Recovery Act (RCRA) and implementing regulations.
- An EPA Administrative Law Judge determined the used KOH was a corrosive, hazardous “spent material,” making it “solid waste” subject to RCRA hazardous-waste requirements; the Environmental Appeals Board affirmed.
- Howmet sought review under the Administrative Procedure Act (APA); the district court granted summary judgment for EPA.
- Howmet appealed to the D.C. Circuit, challenging EPA’s interpretation of “spent material” and asserting lack of fair notice.

## Issues

1. Whether used KOH that could no longer serve as a cleaning solution without processing, but was shipped for use as a fertilizer ingredient, qualified as “spent material” and thus “solid waste” under EPA’s RCRA regulations.
2. Whether EPA’s interpretation of the phrase “purpose for which it was produced” in the “spent material” definition was permissible and entitled to deference.
3. Whether EPA’s enforcement action violated due process fair-notice requirements.

## Decision

- The D.C. Circuit affirmed the district court’s summary judgment for EPA.
- The court held EPA reasonably classified Howmet’s used KOH as “spent material” because contamination prevented it from serving its original cleaning purpose without processing.
- The court deferred to EPA’s interpretation of its own ambiguous regulation, finding it not plainly erroneous or inconsistent with the regulatory text and structure.
- The court rejected Howmet’s fair-notice argument, concluding the regulatory definition and EPA interpretive guidance provided adequate notice that the used KOH would be regulated as hazardous waste.

## Legal Principles

- Under EPA’s RCRA regulations, a “spent material” is a used material that, due to contamination, can no longer serve the purpose for which it was produced without processing; once “spent,” it is “solid waste” and may be hazardous if it is listed or exhibits a hazardous characteristic.
- When an agency interprets an ambiguous regulation it administers, a court may defer to the agency’s reading if it is reasonable and consistent with the regulation’s text, history, and the agency’s prior interpretations.
- Transfer or sale of a contaminated material for reuse in a different process does not necessarily prevent it from being treated as “discarded” for purposes of “solid waste” classification, particularly where hazardous characteristics persist and land application is involved.
- In administrative enforcement, fair notice can be satisfied by the regulatory text together with longstanding agency interpretations and guidance, so long as regulated entities are not subjected to unfair surprise.

## Conclusion

The D.C. Circuit upheld EPA’s enforcement action, concluding that Howmet’s contaminated KOH was “spent material” and therefore “solid waste” subject to hazardous-waste controls, and that EPA’s interpretation merited deference and provided sufficient notice to support penalties under RCRA.


Howmet Corp. v. EPA, 614 F.3d 544 (D.C. Cir. 2010)