§ 562. Powers additional and supplemental. The powers conferred by this article shall be in addition and supplemental to existing powers relating to the effectuating of an urban renewal program, and this Article of the provisions of any other law, general or special. Nothing in this article shall be deemed to relieve any agency or municipality from complying with the provisions of article fifteen of this chapter as they relate to the designation of an urban renewal area or the approval of an urban renewal plan.