(a) Applications shall not generally be subject to public notice, public comment, or public hearings. Applications during the period of review as stated in § 21.5, or during the period of appeal as provided in § 21.8, shall be available for public inspection. Approved applications as provided in § 21.10(d) shall be available for public inspection at all times during the five year period.

(b) The Regional Administrator, if he believes that the addition, alteration, or method of operation may adversely and significantly affect an interest of the public, shall provide for a public notice and/or public hearing on the application. The public notice and/or public hearing shall be conducted in accordance with the procedures specified for a permit under 40 CFR 125.32 and 125.34(b).

(c) Where the applicant is able to demonstrate to the satisfaction of the Regional Administrator that disclosure of certain information or parts thereof as provided in § 21.3(c)(5) would result in the divulging of methods or processes entitled to protection as trade secrets, the Regional Administrator shall treat the information or the particular part as confidential in accordance with the purposes of section 1905 of Title 18 of the United States Code and not release it to any unauthorized person. Provided, however, That if access to such information is subsequently requested by any person, there will be compliance with the procedures specified in 40 CFR part 2. Such information may be disclosed to other officers, employees, or authorized representatives of the United States concerned with carrying out the Act or when relevant in any proceeding under the Act.