Nothing in this subchapter may be construed to deny any municipality, by ordinance or by law, the exercise of police powers under any general or special act, provided that ordinances and bylaws in furtherance of the intent of this subchapter and promoting the general welfare, public health and public safety are valid unless in direct conflict with this subchapter or any rule or order of the board or commissioner adopted under authority of this subchapter.   [PL 1989, c. 890, Pt. A, §40 (AFF); PL 1989, c. 890, Pt. B, §153 (AMD).]