Petition for rehearing.

1. Within 30 days after the Board has made a decision or issued an order, the aggrieved party may apply for a rehearing by filing a written petition setting forth the grounds for the rehearing. The only grounds for rehearing which will be considered by the Board are: (a) Material mistake or fraud affecting the decision; or (b) The discovery of previously unavailable material evidence. 2. The Board will act upon a petition for rehearing within 30 days after receiving it. If no action is taken by the Board within the 30-day period, the petition is deemed denied.