40 CFR 67.41: When EPA may review.

(a) The Administrator may on his own initiative or on petition review any initial, interim, or final penalty calculation made or approved by the State or local agent to determine whether it conforms to the requirements of the Act, of part 66, of the Technical Support Document and the Instruction Manual. The Administrator shall notify the State or local agent in writing of his intention to review the calculation within 60 days of receipt by EPA of the calculation or any item considered by the State in making or approving such calculation, whichever occurs later.

(b) No such State determination shall become final until the expiration of 90 days after the Administrator's receipt of the notice required by § 67.11(b)(5).

(1) If the Administrator does not issue a notice of intent to review within that period, the State determination shall, upon expiration of such period, constitute final action of the Administrator under section 120 of the Act.

(2) If the Administrator issues a notice of intent to review within that period, the State determination shall not become final until the Administrator takes final action after reviewing the determination.

(c) Except as otherwise provided, a State determination shall be approved if there was a reasonable basis in law and in fact for making the determination.