(1) After a final decision has been issued, any party may submit a petition for reconsideration with the board as provided by RCW 34.05.470. Such petition must be made, by mail or otherwise, within ten business days from the mailing of the final decision, and shall state the specific grounds upon which relief is requested. The petition for reconsideration shall be submitted to the board and served upon all parties and representatives of record in compliance with WAC 456-09-345. The board may require or a party may at its own option, within ten business days of the date of the letter acknowledging receipt by the board of the petition for reconsideration, submit to the board a response together with proof of service pursuant to WAC 456-09-345.

(2) The petition shall be deemed denied if, within twenty calendar days from the date the petition is received by the board, the board does not either dispose of the petition; or provide the parties with a written notice specifying the date by which it will act on the petition.

(3) The disposition shall be in the form of a written order denying the petition, granting the petition and dissolving or modifying the final decision, or granting the petition and setting the matter for further hearing. The board may require the parties to submit written briefs or statements of position or to appear and present oral argument within such time and on such terms as may be prescribed.