(a) Petition for Leave to Intervene. Any person whose interests may be affected substantially by the matters to be considered in a proceeding may petition the Administrative Law Judge for leave to intervene as a party in the proceeding any time after the institution of a proceeding and before such proceeding has been submitted for final consideration. Petitions for leave to intervene shall be in writing and shall set forth with specificity the nature of the petitioner's interest in the proceeding and the manner in which his interests may be affected substantially. The Administrative Law Judge may direct a petitioner requesting intervention to submit himself for examination as to his interest in the proceeding.

(b) Response to petition. A petition for leave to intervene shall be served by the petitioner upon all parties to the proceeding, who may support or oppose the petition in a document filed within ten days after service of the petition upon them or within such other period as the Administrative Law Judge may direct in a particular case.

(c) Leave to intervene—when granted. No person shall be admitted as a party to a proceeding by intervention unless the Administrative Law Judge is satisfied that (1) a substantial interest of the person seeking to intervene may be adversely affected by the matter to be considered in the proceeding; (2) that his intervention will not materially prejudice the rights of any party, through delay or otherwise; (3) that his participation as a party will otherwise be consistent with the public interest; and (4) that leave to be heard pursuant to §10.34 would be inadequate for the protection of his interests. The burden shall be upon the petitioner to satisfy the Administrative Law Judge on these issues.

(d) Rights of intervenor. A person who has been granted leave to intervene shall from that time forward have all the rights and responsibilities of a party to the proceeding.