14 CFR §1204.1510

1. (a)If a state provides a state process recommendation to the Agency through its single point of contact, the Administrator either:
   1. (1)Accepts the recommendation;
   2. (2)Reaches a mutally agreeable solution with the state process; or
   3. (3)Provides the single point of contact with a written explanation of its decision, in such form as the Administrator in his or her discretion deems appropriate. The Administrator may also supplement the written explanation by providing the explanation to the single point of contact by telephone, other telecommunication, or other means.
2. (b)In any explanation under paragraph (a)(3) of this section, the Administrator informs the single point of contact that:
   1. (1)The Agency will not implement its decision for a least ten days after the single point of contact receives the explanation; or
   2. (2)The Administrator has reviewed the decision and determined that, because of unusual circumstances, the waiting period of at least ten days is not feasible.
3. (c)For purposes of computing the waiting period under paragraph (b)(1) of this section, a single point of contact is presumed to have received written notification five days after the date of mailing of such notification.