40 CFR § 209.8
Submission of a remedial plan
June 9, 2020
(a) The Administrator may require the respondent to submit a remedial plan. Notice of this requirement and the due date will be given in the complaint. If the respondent requests a hearing, the remedial plan required by the complaint need not be submitted. The final order may include a requirement that the respondent submit a remedial plan.
(b) A respondent may always submit a remedial plan voluntarily in pursuit of informal settlement.
(Sec. 13, Noise Control Act (42 U.S.C. 4912))