In November 1987, P's personnel manager discovered that maintenance workers at P routinely discarded volatile solvent residue behind P's Grain Valley plant. Management was unaware of its employees' practices until the personnel manager filed his report in November 1987. Following the report, P ceased its disposal activities and voluntarily contacted the Missouri Department of Natural Resources (MDNR). The MDNR investigated and concluded that Harmon's past disposal practices did not pose a threat to either human health or the environment. They created a plan whereby P would clean up the disposal area. While P was cooperating with the MDNR, D initiated an administrative enforcement action seeking $2,343,706 in penalties. In harmonizing the details of the plan, P asked the MDNR not to impose civil penalties. Harmon based its request in part on the fact that it voluntarily self-reported the environmental violations and cooperated fully with the MDNR. A Missouri state court judge approved a consent decree entered into by the MDNR and P. MDNR released P from any claim for monetary penalties. P litigated D's claim before an administrative law judge (ALJ). The ALJ found that a civil penalty against P was appropriate in this case and imposed a civil fine of $586,716. A three-person Environmental Appeals Board panel affirmed. P filed a complaint challenging D's decision. A summary judgment order found that D's decision to impose civil penalties violated the RCRA and contravened principles of res judicata. D appealed.