N.Y. Comp. Codes R. & Regs. tit. 6, § 201-5.4 – Permit modifications.

(a) The owner or operator of a facility subject to this Subpart must submit an application for permit modification, as described in section 201-5.2 of this Subpart, prior to commencing construction of either a significant modification as described in subdivision (b) of this section, or a minor modification as described in subdivision (c) of this section.
1. (1) The following changes to existing facilities are considered significant modifications:
  1. (i) changes that cause the facility to become subject to a new applicable requirement;
  2. (ii) changes that result in less stringent monitoring, recordkeeping, or reporting requirements;
  3. (iii) changes that seek to establish or change a case-by-case determination or department approved variance;
  4. (iv) changes that seek to establish or change a federally enforceable emissions cap or a permit term or condition that the facility has accepted to avoid an applicable requirement to which the facility would otherwise be subject; and
  5. (v) changes that are modifications under any provision of title I of the act that result in an emissions increase in excess of the NSR major facility thresholds contained in Subpart 231-13 of this Title.
2. (2) Applications for significant permit modifications are subject to the public noticing requirements for new applications pursuant to the requirements of Part 621 of this Title. The modified permit must be issued before the facility owner or operator may commence construction or operation of the requested modification.
  (c) Minor permit modifications.
3. (1) A minor modification is any change at an existing facility that meets the definition of modification at section 200.1(aq) of this Title and is not a significant modification as described in subdivision (b) of this section.
4. (2) The department will review and act on applications for minor permit modifications in accordance with the requirements for minor projects under Part 621 of this Title.
5. (3) The facility owner or operator may proceed with the requested minor modification upon receipt of a notice of complete application from the department confirming that the modification is minor. If the department fails to make a completeness determination, the application shall be deemed complete by default on the 15th day after receipt of the application and the facility owner or operator may proceed with the requested modification on the 25th day after the date that the department received the application. After the facility owner or operator makes the change and until the department takes final action, or notifies the facility owner or operator that the requested modification does not meet the minor modification criteria, the facility owner or operator must comply with both the applicable requirements governing the change and any proposed permit terms and conditions contained in the application. During this time period, the facility owner or operator need not comply with the existing permit terms and conditions for which a modification is proposed. However, if the facility owner or operator fails to comply with the proposed permit terms and conditions during this time period, the existing permit terms and conditions for which a modification is proposed may be enforced against it.
  (d) Advance notifications.
  The owner or operator of a facility subject to the requirements of this section may make changes that meet all of the criteria in paragraphs (1) through (4) of this subdivision without the prior approval of the department. The owner or operator of the facility must notify the department in writing at least 15 days in advance of making each such change, as described in subdivision (e) of this section.
6. (1) The change is not a significant modification as described in subdivision (a) of this section.
7. (2) The change does not cause facility emissions to exceed any emission limitation or other condition in the facility’s permit or result in emissions of a regulated contaminant not previously emitted or authorized under a permit.
8. (3) The change does not cause the facility to become subject to any additional applicable requirements or regulations under this Title.
9. (4) The change does not seek to establish or change a federally-enforceable emission cap or limit, or the monitoring, recordkeeping, or reporting requirement associated with the emission cap or limit.
(b) Significant permit modifications.
(e) Advance notifications required by subdivision (d) of this section shall include the following information:
1. (1) identification of the emission unit(s), process(es), emission source(s), and emission point(s) affected by the proposed change;
2. (2) date on which the change is to occur;
3. (3) description of the proposed change;
4. (4) if appropriate, the identification and description of emissions control technology and compliance terms; and
5. (5) the identification of all contaminants emitted by the affected emission sources and calculations of the emission rate potential, potential to emit, and projected actual annual emission rates after the proposed change.
(f) The owner or operator of a facility which has made a change pursuant to subdivision (d) of this section must maintain a record of the date and description of each such change at the facility, and shall include each change in the facility’s next permit renewal or modification application. These records shall be maintained at the facility until the changes are incorporated into the facility’s permit and must be made available for review by department representatives upon request.
(g) The department may require a permit modification to impose applicable requirements or permit conditions if it determines that changes proposed pursuant to the advance notification requirements of subdivision (d) of this section do not meet the established criteria, or that the changes may have a significant air quality impact. In such cases, the department shall require that the facility owner or operator not undertake the proposed changes until a permit modification is issued. The department’s determination shall include a listing of any additional information necessary to complete its review of the proposed changes.