If it is determined that approval of the application for amendment of license would constitute a significant alteration of license pursuant to section 6 of the Act, 16 U.S.C. 799, public notice of such application shall be given at least 30 days prior to action upon the application.
Any application for extension of time fixed in the license for commencement or completion of construction of project works must be filed with the Commission not less than three months prior to the date or dates so fixed.