010-23 Wyo. Code R. § 23-8
(a.) Any person interested in obtaining relief sought by a proponent or otherwise interested in the determination of a proceeding pending before the Board, may petition for leave to intervene in such proceeding prior to or at the time it is called for hearing, but not thereafter except for good cause shown. The petition shall set forth the grounds of the proposed intervention, the position and interest of the petitioner in the proceeding, and if affirmative relief is sought, the same should conform to the requirements for a formal complaint. Leave will not be granted except on allegations reasonable pertinent to the issue already presented and which do not unduly broaden them.
If leave is granted, the petitioner becomes an intervener and a party to the proceeding with the right to have notice of, and appear at the taking of testimony, to produce and cross-examine witnesses, and to be heard on the argument of the case.
010-23 Wyo. Code R. § 23-8