(a) If the Administrator finds that the remedial plan is designed to remedy the noncompliance effectively, he or she will so notify the respondent in writing. If the remedial plan is not approved, the Administrator will provide the respondent with written notice of the disapproval and the reasons for the disapproval. The Administrator may give the respondent an opportunity to revise the plan, or the Administrator may revise the plan.

(b) The respondent shall commence implementation of the approved plan upon receipt of notice from the Administrator that the remedial plan has been approved, or revised by the Administrator and then approved.