NSR Program for PM-2.5 NAAQS. Overview of Potential Proposal

Transcription

1 NSR Program for PM-2.5 NAAQS Overview of Potential Proposal

2 PM 2.5 Precursors The CAA defines air pollutant to include any pollutant that enters the air and any precursor to the formation of such pollutant to the extent that the Administrator has identified such precursor emissions for a particular purpose. We specifically indicated that S02 and NOx are likely precursors for PM-10 in the western U.S.. We allowed other States to identify precursors as appropriate to their situation and PM-10 problem.

3 PM2.5 Precursors Scientific evidence suggests SO2, NOx, organic compounds, and NH3 contribute to the formation of PM-2.5 emissions. however, there are also some areas of scientific uncertainty. Requesting comment Should Administrator identify one or more of these pollutants nationally as precursors for the purposes of regulating such pollutants under the NSR program Should EPA defer to States to identify the appropriate precursors for their areas.

4 Potential Options VOC NOx SOx Ammonia All VOC Subset of VOC Only if EPA/State make finding Identify as precursor Identify only if EPA/State make finding Identify as precursor Identify only if EPA/State make a finding Identify only if EPA/State make a finding

5 Condensable Emissions States always required to consider condensable emissions in evaluating PM- 10 emissions from a source Due to variations in PM-10 test methods and emission factors, States have not always reliably quantified condensable emissions from individual sources.

6 Condensible Emissions Condensable emissions are a significant component of PM-2.5 emissions. We intend to require States to use a reliable method to quantify the filterable and condensable portion of the emissions stream for PM-2.5 and PM-10.

7 Major Source Threshold The PM-2.5 program is governed by Subpart 1 of the CAA. 100/250 tpy for attainment and unclassifiable areas 100 tpy for nonattainment areas We may suggest that States consider the effect smaller sources have on their ability to attain or maintain the NAAQS.

8 Significant Emissions Rate (tpy) Propose significant emission rate of 10 tpy for PM-2.5 direct emissions Use methodology comparable to methods used to establish the significant emission rate for TSP and PM10. Take comment on alternative approaches that support a tpy significant emissions rate. Proposing a 40 tpy significant rate for precursors (if applicable) to harmonize implementation of the PM-2.5 NAAQS with the ozone NAAQS.

9 Significant Emission Rate For purposes of the TSP, we established a tpy significant rate at a level that would result in a concentration impact of less than 4% of the 24-hour standard. For purposes of the PM-10 standard, we directly correlated the PM-10, 24-hour standard to the TSP, 24-hour standard and then established the significant emissions rate as a corresponding percentage of the TSP rate. For the PM2.5 emissions rate, we are proposing to rely on a conversion of the PM-10, 24-hour average concentration to an annual value; and, then establish the PM2.5 significant emissions rate as a proportional percentage (75%) of the PM-10 significant rate. Using this approach, we have determined that a 10 tpy emissions increase is unlikely to increase the annual average PM-2.5 concentrations by more than 4% (0.6 ug/m3).

10 Increments and Significant Impact Level (SIL) Still developing approach for increment level for PM-2.5 direct emissions, PM-2.5 precursors, and the baseline trigger date. Meanwhile, States must continue to implement the PM-10 increments. We also will be requesting comment on methods for developing SILs for PM-2.5 direct emissions and precursors.

11 Pre-Construction Monitoring Options Monitoring for all PM-2.5 direct emissions/ precursors, but case-by by- case exemptions when existing PM- 2.5 monitoring network is sufficient. Exempt all PM-2.5 sources from monitoring by determining that the existing network is sufficient.

12 Preconstruction Monitoring Options Exempt sources from pre-construction monitoring if the modeled impacts are below a significant monitoring concentration (SMC). (We would have to develop SMC(s) ) in a separate proposal.) Allow an applicant to use the existing PM-10 (using conversion factors) and PM-2.5 networks to demonstrate, on a case-by by-case basis, that the existing monitoring network is sufficient.

13 Offsets Since the PM-2.5 NAAQS is being implemented under Subpart 1, we intend to propose that the applicable offset ratio be at least 1:1. We intend to propose to allow States to develop interprecursor trading rules for offsets that are supported by a modeling demonstration.

14 Transition into PM-2.5 Program The program will be effective upon designation in Federal PSD areas. Some States will not require SIP changes to implement the PM-2.5 provisions. In these States, the program will be effective immediately upon designation.

15 Transition to PM2.5 Program Where SIP Change Required State must continue to implement PM-10 program as surrogate for PM-2.5 PSD program until revisions to State s Part C SIP approved. Must include condensable emissions. Must comply with Section 110(a)(3) of the Act,which requires an air quality analysis to show that new emissions will not interfere with w the PM-2.5 NAAQS. Appendix S applies in nonattainment areas until State s Part D SIP approved. Most States should have legal authority to implement Appendix S under an existing permitting program. If a State lacks the authority to act, EPA will issue the permit. States must amend their minor NSR permit programs to include PM-2.5 direct emissions (and precursors) as a regulated NSR pollutant.