43 C.F.R. § 4.1156
(a) In a civil penalty proceeding where the person against whom the proposed civil penalty is assessed fails to comply on time with any prehearing order of an administrative law judge, the administrative law judge shall issue an order to show cause why—
(c) Where the person against whom the proposed civil penalty is assessed fails to appear at a hearing, that person will be deemed to have waived his right to a hearing and the administration law judge may assume for purposes of the assessment—