(a) Except as agreed by the parties, a party may request, not later than the 30th day after the date of receipt of the arbitration award, that the arbitration tribunal make an additional award for a claim presented in the arbitration but omitted from the award.
(b) If the arbitration tribunal considers the request to be justified, the tribunal shall make the additional award not later than the 60th day after the date of receipt of the request.