(1) Any labor organization or group of employees may file a petition to intervene within 20 days of the first day of posting of the notice of decertification proceedings.

(2) The original petition shall be signed by the petitioner(s) or their authorized representative.

(3) The original petition and three copies of the petition shall be filed with the board.

(4) The petition shall contain the name and address of petitioner(s) .

(5) The petition shall be accompanied by proof of interest representing 10% of the employees in the unit. Proof shall consist of authorization cards, or copies thereof, which have been individually signed and dated within 6 months of the date of the filing of the petition. The cards shall indicate that the signatories do not desire to be represented for collective bargaining purposes by the board-certified or employer recognized exclusive representative, or that they desire to be represented by the petitioner.

(6) The petition to intervene shall conform in all other respects to the requirements for a petition for decertification.

(7) The board shall serve a copy of the petition to intervene upon all other parties.