O.C.G.A. § 34-9-60 (a) empowers the Board to make rules to carry out the Workers' Compensation Act. "The interpretation of a statute by the agency charged with enforcing or administrating its provisions is to be given great weight and deference, unless contrary to law." See Smith v. Mr. Sweeper Stores, Inc., 247 Ga. App. 726, 544 S.E.2d 758 (2001).