(1) Within thirty days of receipt by the board, if any petition for review is found to be defective or insufficient, the board may require the party filing the petition for review to correct, clarify or amend the same to conform to the requirements of chapter 90.58 RCW and the board's rules. The board may refuse to schedule any conference or hearing thereon until compliance with such requirements, or may issue an appropriate order which may include providing for dismissal of the petition upon failure to comply within a specified time.

(2) Other amendments and supplemental pleadings shall conform to civil rule 15.