Variances and temporary emergency variances may be granted by the Secretary from any regulation adopted pursuant to this chapter in accordance with §§ 6011 and 6012 of this title except that no variance or temporary emergency variance shall be granted which would be inconsistent with the no less stringent requirements of § 9004 of the Resource Conservation and Recovery Act of 1976, Pub. L. 94-580 as amended by Pub. L. 98-616 [42 U.S.C. § 6991c] (or regulations promulgated thereunder).