## Facts

- Mobil Oil Corporation operated Port Mobil, a petroleum storage and distribution facility on Staten Island, New York.
- Port Mobil included barge-cleaning operations in which water was injected into barges’ holds to wash out petroleum residue, generating benzene-containing wastewater.
- Mobil used a multistep recovery process to separate and recover petroleum from the wash water; as a final step, remaining wastewater was dumped into an on-site artificial pond for storage.
- The same pond also received other water streams, including stormwater runoff and residual water pumped from recovery wells.
- These different streams were sometimes mixed before reaching the pond, and they were commingled in the pond.
- In 1990, the EPA issued a regulation treating waste containing more than 0.5 mg/L of benzene as hazardous waste and requiring a RCRA permit for facilities disposing of such waste.
- Mobil sampled its waste streams and determined that Port Mobil’s waste met the benzene threshold for hazardous waste.
- Mobil applied for a permit but was denied for failing to meet requirements under the Resource Conservation and Recovery Act (RCRA).
- After the permit denial, Mobil continued disposing of the barge-cleaning wastewater into the pond without a permit for about a year.
- EPA took its own samples and confirmed that the waste was hazardous.
- The United States sued Mobil seeking injunctive relief and civil penalties under RCRA.
- Mobil asserted affirmative defenses arguing the barge waste was misclassified as hazardous because EPA’s testing approach was wrong; Mobil contended benzene levels should be determined using a long-term average measured at the point where waste entered the pond, based on the combined mixture of all three water sources.
- The United States moved to strike Mobil’s affirmative defenses.

## Issues

1. Whether Mobil could assert affirmative defenses based on the theory that hazardous-waste classification must be determined by long-term averaging of benzene concentrations at a commingled pond discharge point, rather than by measuring the regulated waste stream without dilution.

## Decision

- The court granted the United States’ motion to strike Mobil’s affirmative defenses premised on long-term averaging and commingled-stream testing.
- The court rejected Mobil’s effort to treat the combined, diluted mixture in the pond (or at the pond entry point) as the proper basis for determining whether the barge-cleaning wastewater was hazardous under RCRA.
- The case proceeded without those defenses.

## Legal Principles

- An affirmative defense may be stricken when, even if its factual allegations are assumed true, the defense fails as a matter of law.
- RCRA hazardous-waste applicability is determined by reference to the regulated waste as generated or managed, not by dilution through commingling with other, nonhazardous streams.
- A regulated entity cannot avoid hazardous-waste requirements by mixing hazardous process wastewater with stormwater or other waters and then relying on a long-term averaged concentration from the resulting mixture.

## Conclusion

In this RCRA enforcement action involving benzene-contaminated barge-cleaning wastewater at Mobil’s Port Mobil facility, the court struck Mobil’s affirmative defenses that depended on testing a commingled pond mixture and using long-term averaging to reduce measured benzene concentrations. The court held that hazardous-waste status could not be avoided by dilution through mixing and that the challenged defenses were legally insufficient.


United States v. Mobil Oil Corp., 1997 WL 1048911 (1989)