(1) Upon timely application, any person shall be permitted to intervene when a statute confers an unconditional right to intervene or when the representation of an applicant's interest is or may be inadequate; or
(2) Upon timely application, any person may be permitted to intervene when a statute confers a conditional right to intervene or when the applicant's claim or defense and the main action have a question of law or fact in common. In exercising its discretion, the agency shall consider whether the intervention will unduly delay or prejudice the adjudication of the rights of existing parties.