(1) An ALJ or other presiding officer may grant a petition for intervention pursuant to RCW 34.05.443.

(2) A request to intervene will be handled as a prehearing motion. The ALJ may allow intervention if:

(a) The intervenor is not a party to the matter but has a substantial interest in the outcome of the matter and the interest of the intervenor is not adequately represented by a party; or

(b) Other good cause exists.

(3) If intervention is granted, the intervenor, though not a party, must comply with this chapter as a party to the proceeding would, unless otherwise limited in the order granting intervention.