D's transformers contained PCBs, and P had to comply with the disposal requirements of 40 C.F.R. Sec. 761.60. Section 761.60(b)(1) requires the disposal of transformers by either incinerating the transformer, or by placing it into a chemical waste landfill after the PCB-laced dielectric fluid has been drained and the transformer rinsed with a PCB solvent. D originally incinerated its transformers. D changed these procedures and began a recycling process that recovered a portion of the dirty solvent from transformers through distillation. After soaking the transformer, D poured the dirty solvent into a still that heated the freon, boiling off about 90% of it. The 10% of the liquid that was left, which was highly contaminated with presumably all the PCBs that had been rinsed from the transformer, and was immediately incinerated. The vapor from the still was cooled, recondensing into nearly pure liquid freon that contained less than the regulatory threshold of 50 ppm PCBs (2 ppm in fact). D then used this recycled solvent to rinse other transformers. P disagreed about whether the intervening distillation and recycling process violated the regulations. The ALJ fined D $25K. The EPA Board (P) upheld that decision. D appealed contending that P’s interpretation of the rule was arbitrary and capricious and that imposing a fine was violative of due process because the regulations were ambiguous in that D lacked notice that P forbade distillation.