Washington Revised Code Title 34. Administrative Law § 34.05.443. Intervention

(1) The presiding officer may grant a petition for intervention at any time, upon determining that the petitioner qualifies as an intervenor under any provision of law and that the intervention sought is in the interests of justice and will not impair the orderly and prompt conduct of the proceedings.

(2) If a petitioner qualifies for intervention, the presiding officer may impose conditions upon the intervenor's participation in the proceedings, either at the time that intervention is granted or at any subsequent time. Conditions may include:

(3) The presiding officer shall timely grant or deny each pending petition for intervention, specifying any conditions, and briefly stating the reasons for the order. The presiding officer may modify the order at any time, stating the reasons for the modification. The presiding officer shall promptly give notice of the decision granting, denying, or modifying intervention to the petitioner for intervention and to all parties.