The certification requirement with respect to an application for a license or permit shall be waived upon:
(a) Written notification from the State or interstate agency concerned that it expressly waives its authority to act on a request for certification; or
(b) Written notification from the licensing or permitting agency to the Regional Administrator of the failure of the State or interstate agency concerned to act on such request for certification within a reasonable period of time after receipt of such request, as determined by the licensing or permitting agency (which period shall generally be considered to be 6 months, but in any event shall not exceed 1 year). In the event of a waiver hereunder, the Regional Administrator shall consider such waiver as a substitute for a certification, and as appropriate, shall conduct the review, provide the notices, and perform the other functions identified in Sec. Sec. 121.13, 121.14, and 121.15. The notices required by Sec. 121.13 shall be provided not later than 30 days after the date of receipt by the Regional Administrator of either notification referred to herein.