40 C.F.R. § 24.07
The respondent may request an informal settlement conference at any time by contacting the appropriate EPA employee, as specified in the initial administrative order. A request for an informal conference will not affect the respondent's obligations to timely request a hearing. Whether or not the respondent requests a hearing, the parties may confer informally concerning any aspect of the order. The respondent and respondent's representatives shall generally be allowed the opportunity at an informal conference to discuss with the appropriate Agency technical and legal personnel all aspects of the order, and in particular the basis for the determination that a release has occurred and the appropriateness of the ordered corrective action.
40 C.F.R. § 24.07