D E C banner
D E C banner

Disclaimer

The New York State Department of Environmental Conservation has added a link to a translation service developed by Microsoft Inc., entitled Bing Translator, as a convenience to visitors to the DEC website who speak languages other than English.

Additional information can be found at DEC's Language Assistance Page.

Part 231 New Source Review for New and Modified Facilities Frequently Asked Questions

Question 1) What is Part 231?

Answer 1) Part 231 is the Department's regulation implementing the Clean Air Act's New Source Review program. It provides for the review of the air pollution impacts of new major stationary sources and modifications to existing major stationary sources in air pollution attainment and non-attainment areas of the State.

Question 2) What is new source review (NSR)?

Answer 2) NSR is a permitting process that requires industry to undergo a pre-construction review to determine the appropriate air pollution controls. NSR consists of two components: attainment NSR (a.k.a. prevention of significant deterioration (PSD)) and non-attainment NSR. Part 231 is New York State's NSR regulation.

Question 3) What is the effective date of Part 231?

Answer 3) The effective date of Part 231 is February 19, 2009. Revised Part 231 (specifically Subparts 231-3 through 231-13) applies to all applications determined complete on or after the effective date.

Question 4) Is there a transition plan from the Department's previous Part 231 to the current Part 231?

Answer 4) Yes, the Department has incorporated a transition plan into the regulation. This plan is outlined in section 231-3.2.

Question 5) What facilities are subject to the provisions of Part 231?

Answer 5) Part 231 applies to new major stationary sources and existing major sources which make modifications. Basically the rule requires sources to determine their emissions of regulated air pollutants and in the case of an existing air pollution source compare those emissions post modification to baseline emissions to determine the significance of the emission increase. Sources that make minor modifications may have reporting and recordkeeping requirements. Sources that make major modifications, in addition to reporting and recordkeeping requirements, will need to obtain a new or modified air pollution permit and apply pollution control equipment, and may need to obtain emission offsets. Requirements vary depending on whether the facility is subject to the "attainment" provisions of Part 231 or "nonattainment" provisions.

Question 6) What contaminants are non-attainment in New York State?

Answer 6) Ozone, particulate matter less than 10 microns (PM-10), and particulate matter less than 2.5 microns (PM-2.5) are currently designated as non-attainment contaminants in New York State. Ozone is regulated by its precursors; volatile organic compounds (VOC) and oxides of nitrogen (NOx). The Department's Part 200 regulation defines the specific areas of the State that are designated as non-attainment for these contaminants. Please see Part 200 for these specific areas.

Question 7) What contaminants are attainment in New York State?

Answer 7) The attainment contaminants in New York State are sulfur dioxide (SO2), particulate matter (PM), PM-10, PM-2.5, carbon monoxide (CO), NOx (New York State is in attainment for NOx, however, as an ozone precursor there is a dual review for attainment and non-attainment), lead, and any other NSR regulated contaminant. For a complete list of NSR regulated contaminants, please see the Subpart 231-13 contaminant tables.

Question 8) What requirements apply when a proposed major project becomes subject to Part 231?

Answer 8) A proposed major project that becomes subject to Part 231 must apply air pollution controls based on a control technology analysis. Attainment contaminants subject to Part 231 must apply best available control technologies (BACT). Non-attainment contaminants subject to Part 231 must apply lowest achievable emission rates (LAER) and obtain emission offsets.

Question 9) What is BACT?

Answer 9) BACT (best available control technology) is a top-down analysis used to determine the best control technology available for controlling an attainment contaminant. This analysis contains both an economic (dollars per ton of contaminant removed) and a technical aspect (i.e. can the control physically be installed).

Question 10) What is LAER?

Answer 10) LAER (lowest achievable emission rate) is a control technology analysis that requires the most stringent controls be used to reduce non-attainment contaminants. Unlike BACT, a LAER analysis does not have an economic aspect.

Question 11) How does a facility become subject to the BACT and/or LAER requirements of Part 231?

Answer 11) For a new facility to become subject to the requirements, the emissions from the proposed facility must equal or exceed the applicability thresholds in Subpart 231-13. For an existing facility to become subject to the requirements, two conditions must be met: a modification must be proposed, and the emissions from the proposed modification must equal or exceed the applicable thresholds in Subpart 231-13, thus resulting in an NSR major modification. Please note that the applicability thresholds vary depending on whether the proposed project is a new facility or is a modification to an existing facility and that the threshold for each contaminant is dependent upon whether the contaminant is attainment or non-attainment.

Question 12) What are emission offsets and when are they required?

Answer 12) Emission offsets are emission reductions (which have been approved as emission reduction credits (ERCs)) that are required to be obtained by a proposed new major facility or by an existing major facility that undertakes an NSR major modification. Emission offsets are required by facilities located in a nonattainment area or an attainment area of the state within the ozone transport region. A proposed project for a non-attainment contaminant must offset their emissions by obtaining ERCs at an offset ratio specified in Subpart 231-13. The offset ratio varies depending on the contaminant and non-attainment status of the area of the state that the project is occurring.

Question 13) What is a modification?

Answer 13) Any physical change in, or change in the method of operation of, a facility which results in a level of annual emissions in excess of the baseline actual emissions of any regulated NSR contaminant emitted by such facility or which results in the emission of any regulated NSR contaminant not previously emitted. A modification does not include routine maintenance, repair and replacement (RMRR) and other specific activities (as defined in Subpart 231-4).

Question 14) How are RMRR activities determined?

Answer 14) Part 231 uses a four factor test on a case-by-case basis to determine if the activity meets the Part 200 definition of RMRR. If this definition is met by the proposed project then the project is no longer considered a modification.

Question 15) Is there a list of clearly defined repairs or activities that are considered RMRR activities?

Answer 15) There are no predetermined activities that are considered RMRR activities. RMRR determinations are made on a case-by-case basis considering four factors, namely the nature/extent, purpose, frequency, and cost of the work. However, there are some activities that might qualify as RMRR activities. For an electric generating facility these activities include, but are not limited to: cleaning of a boiler or other source and related ductwork to facilitate maintenance access and inspections; inspection of the furnace and gas path; inspection including non-destructive examination of known trouble areas; individual tube repair/replacement; inspection of tube shields and high erosion areas; inspection, repair and replacement of refractory in the slag necks and troughs; inspection and repair of ductwork and expansion joints; cleaning and inspection of boiler penthouses; water blasting, inspection, stud replacement and new refractory (cyclone fired boilers); inspection and repair of boiler casing, doors and inspection ports; inspection and repair of gas path deflection baffles and flow distributors; inspection and repair of all dampers (air and gas); removal, disassembling, inspection and repair of ignitors; cleaning, inspection and repair of external steam header vestibules; pressure testing water and steam tubing components; chemical cleaning of water-side tubing to remove internal deposits, inspections for leak detection (on pipes, tubes, and/or valves).

Question 16) Is there a list of clearly defined repairs or activities that are considered activities that extend the life of a facility, and consequently are not RMRR activities?

Answer 16) There are no predetermined activities that are considered life extending. RMRR determinations are made on a case-by-case basis considering four factors, namely the nature/extent, purpose, frequency, and cost of the work. However, there are some activities that are likely to extend the life of a facility. For an electric generating facility these activities include, but are not limited to: the replacement of a boiler's super heater, the replacement of a fuel feed system, the replacement of a burner or burners, repairs that allow an emission source to regain lost operating capacity, and replacements of components that increase the capacity of the emission source beyond its original design.

Question 17) Is there a "special" Part 231 application that a facility would need to submit?

Answer 17) No, a Part 201 application must be used.

Question 18) Are there specific application requirements in Part 231?

Answer 18) Yes, there are requirements that a facility must comply with as part of their application. These requirements include, but are not limited to, a project description, BACT or LAER analysis, sources of emission offsets (if required), and proposed record keeping and monitoring requirements.

Question 19) Does Part 231 require facilities, subject to the rule, maintain records to prove compliance with their BACT or LAER limitations?

Answer 19) Yes, Part 231 requires specific record keeping; these record keeping provisions are in Subpart 231-11.

Question 20) Does Part 231 require facilities with insignificant projects to maintain records to prove that the project is insignificant (i.e., below the applicability thresholds)?

Answer 20) Yes, Part 231 requires specific record keeping; these record keeping provisions are in Subpart 231-11.

Question 21) Must a source owner that has received a permit or permit modification for a proposed source project subject to Part 231 commence construction within a specified timeframe?

Answer 21) Yes, the existence of a valid permit shall not be construed as authorizing construction if construction is not commenced within 18 months after the date of permit issuance, if construction is discontinued for a period of 18 months or more, or if construction is not completed within a reasonable time as determined by the department. The department may grant one extension for a period not to exceed 18 months upon a satisfactory showing that an extension is justified. A permit shall become subject to revocation or modification if construction is not commenced and completed within the time frames described above.

Question 22) Must a source owner that has proposed a source project wait until the Department issues a permit to commence construction of the proposed project?

Answer 22) Yes, construction of a proposed project can not commence prior to the issuance of a permit. The timeframe for the Department's review of a permit application and the issuance of a permit is governed by the provisions of the Department's Part 621 regulation.

Question 23) What is netting?

Answer 23) Netting is the process used by an existing major facility to avoid being subject to the BACT or LAER requirements of Part 231 for a proposed project. The netting process is a calculation involving the proposed project emissions increase in addition to past emission increases and decreases that occurred during the contemporaneous period ("The period beginning five years prior to the proposed commence construction date of the new or modified emission source, and ending with the proposed commence operation date.") associated with the proposed project.

Question 24) What permitting requirements apply to facilities that use the netting process to avoid BACT or LAER?

Answer 24) Facilities must apply for a permit. This permit application is considered a Part 201 major modification. The permit will include an emission limit that allows the facility to avoid the requirements of BACT or LAER.


  • Contact for this Page
  • NYSDEC
    Division of Air Resources
    Part 231 Implementation Guidance
    625 Broadway
    Albany, NY 12233-3254
    518-402-8403
    Send us an email
  • This Page Covers
  • Page applies to all NYS regions