The designated State agency or agencies and the Department of Labor, OSHA, shall be the initial parties to the proceedings. Other interested persons may, at the discretion of the administrative law judge, be granted the right to participate as parties if he determines that the final decision could substantially affect them or the class they represent or that they may contribute materially to the disposition of the proceedings.

Any person wishing to participate in any proceeding as a party under paragraph (a) of this section shall submit a petition to the administrative law judge within 30 days after the notice of such proceeding has been published in the FEDERAL REGISTER. The petition shall also be served upon the other parties. Such petition shall concisely state:

Petitioner's interest in the proceeding;

How his participation as a party will contribute materially to the disposition of the proceeding;

Who will appear for petitioner;

The issue or issues as set out in the notice published under § 1955.10 of this part on which petitioner wishes to participate; and

Whether petitioner intends to present witnesses.

The administrative law judge shall, within 5 days of receipt of the petition, ascertain what objections, if any, there are to the petition. He shall then determine whether the petitioner is qualified in his judgment to be a party in the proceedings and shall permit or deny participation accordingly. The administrative law judge shall give each petitioner written notice of the decision on his petition promptly. If the petition is denied, the notice shall briefly state the grounds for denial. Persons whose petition for party participation is denied may appeal the decision to the Secretary within 5 days of receipt of the notice of denial. The Secretary will make the final decision to grant or deny the petition no later than 20 days following receipt of the appeal.

Where the petitions to participate as parties are made by individuals or groups with common interests, the administrative law judge may require all such petitioners to designate a single representative, or he may recognize one or more of such petitioners to represent all such petitioners.