(a) After conclusion of a hearing, but before issuance of an opinion or order, a party may file with the commission a petition to set aside submission and reopen the proceeding for the taking of additional evidence in conformance with Form 2540. The petition shall specify the facts claimed to constitute grounds for justification thereof, including material changes of fact or of law alleged to have occurred since the conclusion of the hearing. It shall contain a brief statement of the proposed additional evidence and explain why such evidence was not previously adduced. On the commission's approval, the additional evidence may be received.

(b) After conclusion of a hearing, but before issuance of an opinion or order, the parties may agree to a settlement and seek to set aside the submission of the case. On the commission's approval, an order incorporating the settlement may issue, or the case may be dismissed and the petition refused and rejected.