Persons not parties to the proceedings who wish to file briefs may do so by leave of the Environmental Appeals Board or the administrative law judge, as appropriate, granted on motion. This motion shall identify the interest of the applicant and shall state the reasons why the proposed amicus brief is desirable. An amicus curiae shall be eligible to participate in any briefing following the granting of his or her motion, and shall be served with all briefs, reply briefs, motions and orders relating to issues to be briefed.