(1) An organization not covered by WAC 391-25-170 may, by motion, intervene in proceedings under this chapter and, upon granting of its motion for intervention, shall be entitled to participate in the proceedings and have its name listed as a choice on the ballot in any election. The motion for intervention shall be supported by a showing of interest indicating that the intervenor has the support of ten percent or more of the employees in the bargaining unit which the petitioner claims to be appropriate. A showing of interest filed in support of a motion for intervention shall be subject to the requirements and confidentiality protections of WAC 391-25-110. A motion for intervention may be granted conditionally subject to the subsequent furnishing of a showing of interest under such conditions as the agency may impose to avoid undue delay of the proceedings.

(2) No motion for intervention shall be considered if made:

(a) After the close of the hearing on the petition;

(b) More than seven days after the filing and posting of an election agreement or cross-check agreement; or

(c) More than seven days after the posting of an investigation statement.