Not later than eighteen months after October 21, 1976, and after notice and hearing, the Administrator shall, after consultation with appropriate Federal, State, and local authorities, promulgate regulations containing guidelines to assist in the development and implementation of State solid waste management plans (hereinafter in this chapter referred to as “State plans”). The guidelines shall contain methods for achieving the objectives specified in section
6941 of this title. Such guidelines shall be reviewed from time to time, but not less frequently than every three years, and revised as may be appropriate.