NO2, SO2, PM2.5, Oh my!?! Information Session EPA R/S/L Modelers Workshop May 10, 2010
Purpose & Outline Provide background and updates on permit modeling processes and technical aspects related to new NAAQS and related policy changes. What new NAAQS? Applicability of Federal PSD requirements Modeling under PSD Walk through each new NAAQS SO2, NO2, PM2.5 2
Ongoing National Ambient Air Quality Reviews Lead NO 2 Primary SO 2 Primary Ozone CO PM NO 2 /SO 2 Secondary Proposal New schedule being developed Jun 26, 2009 Nov 16, 2009 Jan 6, 2010 Oct 28, 2010 Nov 2010 July 12, 2011 Final Oct 15, 2008 Jan 22, 2010 Jun 2, 2010 Aug 31, 2010 May 13, 2011 July 2011 Mar 20, 2012 NOTE: Underlined dates indicate court-ordered or settlement agreement deadlines. 3
Anticipated NAAQS Implementation Milestones Pollutant NAAQS Promulgation Date Designations Effective (approximate date) 110(a) SIPs Due (3 yrs after NAAQS promulgation) Attainment Demonstration Due Attainment Date PM 2.5 (2006) Sept 2006 Nov 2009 Sept 2009 Nov 2012 Nov 2014/2019 Pb Oct 2008 Nov 2010/2011 (extra time for new monitors) Oct 2011 June 2012/2013 Nov 2015/2016 NO 2 (primary) SO 2 (primary) Jan 2010 Feb 2012 Jan 2013 Aug 2013 Feb 2017 June 2010 July 2012 June 2013 Jan 2014 July 2017 Ozone Aug 2010 Aug 2011 (based on 2008-10 data) Aug 2013 Dec 2013 (to be proposed) Dec 2017 (Moderate) CO May 2011 June 2013 May 2014 Dec 2014 May 2018 PM 2.5 (2011) July 2011 Aug 2013 July 2014 Aug 2016 Aug 2018/2023 NO 2 /SO 2 Secondary March 2012 April 2014 March 2015 Oct 2015 N/A 4
Primary Standards Secondary Standards Pollutant Level Averaging Time Level Averaging Time Carbon Monoxide 9 ppm (10 mg/m 3 ) 35 ppm (40 mg/m 3 ) 8-hour (1) 1-hour (1) Lead 0.15 µg/m 3 (2) Rolling 3-Month Average Same as Primary None Nitrogen Dioxide Particulate Matter (PM 10 ) 1.5 µg/m 3 Quarterly Average Same as Primary 53 ppb (3) Annual (Arithmetic Average) Same as Primary 100 ppb 1-hour (4) None 150 µg/m 3 24-hour (5) Same as Primary Particulate Matter (PM 2.5 ) 15.0 µg/m 3 Annual (6) (Arithmetic Average) Same as Primary Ozone 35 µg/m 3 24-hour (7) Same as Primary 0.075 ppm (2008 std) 0.08 ppm (1997 std) 8-hour (8) 8-hour (9) Same as Primary Same as Primary 0.12 ppm 1-hour (10) Same as Primary Sulfur Dioxide 0.03 ppm Annual (Arithmetic Average) 0.14 ppm 24-hour (1) 0.5 ppm 3-hour (1) 5
Applicability of Federal PSD Permit Requirements for New NAAQS April 1, 2010 Steve Page memorandum states EPA generally interprets the CAA and EPA s PSD permitting program regulations to require each final PSD permit decision reflect consideration of NAAQS that are in effect at time permitting authority issues final permit. New NO2 NAAQS on Jan. 22, 2010 with final rule published in Federal Register on February 9 th and becomes effective on April 12, 2010. No grandfathering provision related to new 1-hr NAAQS for permits in process but not yet issued as of that date. http://www.epa.gov/region07/air/nsr/nsrmemos/psdnaaqs.pdf 6
Modeling Under PSD Air quality models (screening and refined) are used in various ways under the PSD program. Step 1: Significant Impact Analysis Use of either screening or refined model to determine if emissions from PSD project alone are significant. If not significant, no further modeling required. If significant, cumulative impact analysis of PSD project and other nearby sources required for all applicable NAAQS and increments Step 2: Cumulative Impact Analysis Use of refined models to determine cumulative impacts from PSD project in conjunction with nearby sources does not cause or contribute to violations of applicable NAAQS and increments. If violation occurs, PSD policy is to determine if PSD project contributes significantly to violation at the exact time and location where violation is predicted by modeling. If PSD project does not contribute significantly at the same time and location where violation was predicted by modeling, project can move forward. If PSD project is contributes significantly, PSD permit cannot be issued until contribution to violation is mitigated. 7
SO2 NAAQS: Status On November 16, 2009, EPA proposed to strengthen the NAAQS for sulfur dioxide (SO2) by revising the primary SO2 standard, designed to protect public health, to a level of between 50 and 100 parts per billion (ppb) measured over 1- hour (~130 to 260 µg/m3) EPA will issue a final rule by June 2, 2010. EPA is considering the need for changes to the secondary standard under a separate review. 8
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NO2 NAAQS: Status On January 22, 2010, EPA strengthened the health-based National Ambient Air Quality for nitrogen dioxide (NO2) by setting a new 1-hour NO2 standard at the level of 100 parts per billion (ppb) (~190 µg/m3) EPA established a new form for the 1-hour NO2 standard as the 3-year average of the 98th percentile of the annual distribution of daily maximum 1-hour average concentrations. EPA is considering the need for changes to the secondary standard under a separate review. 10
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NO2 Monitoring Network To determine compliance with the new standard, EPA is establishing new ambient air monitoring and reporting requirements for NO2. In urban areas, monitors are required near major roads as well as in other locations where maximum concentrations are expected. Additional monitors are required in large urban areas to measure the highest concentrations of NO2 that occur more broadly across communities. Working with the states, EPA will site a subset of monitors in locations to help protect communities that are susceptible and vulnerable to NO2-related health effects. 12
Near Road NO 2 Monitors Are Required in 102 Urban Areas Not shown on map Anchorage, Alaska Honolulu, Hawaii San Juan, Puerto Rico Minimum Near-Road NO 2 Monitoring Requirements 78 areas would require 1 monitor (> 500,000 population) 24 areas would require 2 monitors (> 2.5 million population or road segments with annual average daily traffic counts > 250,000 vehicles) Monitors required no later then January 1, 2013 126 total monitors Approximately 40 additional monitors will be placed in locations to help protect communities that are susceptible and vulnerable to NO2-related health effects 13
Community-Wide NO 2 Monitors Are Required in 53 Urban Areas Not shown on map San Juan, Puerto Rico Honolulu, Hawaii Minimum Community-wide NO 2 Monitoring Requirements 53 areas would require 1 monitor (> 1 million population) 418 existing NO 2 monitoring sites in 2008 Many of these sites would satisfy the proposed community-wide monitoring requirements. Monitors required no later then January 1, 2013 14
Background for NO2 NAAQS and PSD PSD rules apply to any new or revised NAAQS on the effective date of the NAAQS New 1-hour NO2 NAAQS published on Feb 9, 2010; effective date is April 12, 2010 (Page memorandum, April 1, 2010) There is concern about the anticipated difficulties in demonstrating compliance with the new NAAQS Compliance with the NO2 NAAQS has generally not been an issue, because previously only an annual NAAQS for NO2 15
Modeling Guidance for 1-Hour NO2 NAAQS Under PSD PSD regulations requires that modeling be conducted in accordance the Guideline on Air Quality Models Appendix W to 40 CFR Part 51 ( Guideline on Air Quality Models ) outlines recommendations and requirements for PSD permit modeling procedures AERMOD is the EPA Preferred Model for PSD modeling for all criteria pollutants. AERMOD simulates dispersion of inert pollutants and provides estimates of concentrations from 1-hour to annual averages Appendix W outlines screening level procedures to estimate conversion of NO2 from NOx emissions. EPA uses screening methods to account for the amount of conversion. 16
EPA Actions on Modeling Guidance Emissions Provide background on inventory development methods to generate hourly emissions for purposes of modeling NO2 Air Quality Modeling AERMOD is the EPA Preferred Model for NSR/PSD permit modeling Issue clarification memo on how Appendix W s 3-tiered screening level procedures, involving the conversion of NOx to NO2, apply to new hourly standard Tier 1 = 100% conversion Tier 2 = 75% conversion based on ambient ratios Tier 3 = Case-by-case methods based on stack ratios, etc. Provide post-processing tool to generate appropriate modeling results for comparison to new hourly standard We believe that sources will benefit significantly from use of the conversion guidance (Tier 3 options), rather than conservative assumption that all NOx is NO2 (Tier 1 option) Date for issuing guidance and providing processing tool: May 28, 2010 17
Emissions Inventory Hourly NO2 Model emission rates for short term NAAQS are computed consistent with the requirements of Section 8.1 of Appendix W to 40 CFR Part 51, Tables 8-1 and 8-2. The maximum allowable (SIP approved process weight rate limits) or federally enforceable permit limit emission rates assuming design capacity or federally enforceable capacity limitation are used to compute hourly emissions for dispersion modeling against short term NAAQS such as the new 1-hour NO2 NAAQS. If a source assumes a limit on the hourly firing capacity of a boiler, this is reflected in the calculations. Otherwise, the design capacity of the source is used to compute the model emission rate. Permit may not have an enforceable hourly limit. Although for enforcement testing purposes, a short-term limit should exist. We understand that a state likely will not have established a limit for hourly NO2. This is just a quotation from Section 8.1 of Appendix W. Under this scenario, the maximum allowable is SIP approved equivalent of the process weight rate. States will have these backstop limits in their SIP for both SO2 and NO2 in addition to the old PM process weight rate limits. 18
EXAMPLE - ANNUAL Data derived for the annual state emission inventory (EI) is different than how it is computed for near-field dispersion modeling. A source computes their annual emissions based upon the AP-42 emission factor multiplied by the total annual throughput or total fuel combusted. In the 30 MMBtu/hr boiler example, the annual NOx emissions reported to the NEI is computed by: Eannual = (AP-42 emission factor) x (total annual fuel combusted) Eannual = (100 lbs/106 SCF) x (100 106 SCF/yr) = 10,000 lbs. NOx/yr or 5 tons NOx/yr 19
EXAMPLE 1 HOUR An uncontrolled natural gas package boiler with a design firing rate of 30 MMBtu/hr. The AP-42 emission factor for an uncontrolled natural gas external combustion source (AP-42, Section 1.4) for firing rates less than 100 MMBtu/hr is 100 lbs. NOx/106 SCF natural combusted. The hourly emission rate is derived by converting the emission factor expressed in terms of lbs. NOx/106 SCF to lbs. NOx/MMBtu. The conversion is done by dividing the 100 lbs. NOx/106 SCF by 1,020 to convert the AP-42 factor to lbs. NOx/MMBtu. The new emission factor is now 0.098 lbs. NOx/MMBtu. For this example, the source has no limit on the hourly firing rate of the boiler; therefore, the maximum hourly emissions are then computed by multiplying the design firing rate of the boiler by the new emission factor. Ehourly = 0.098 lbs/mmbtu x 30MMBtu/hr = 2.94 lbs/hr Thus 2.94 lbs/hr represents the emission rate that would be input into the dispersion model for modeling against the 1-hour NO2 NAAQS to comply with emission rate requirements of Section 8.1 of Appendix W. 20
Current NO2 Screening Procedures Tier I Assume total conversion of NO NO2 Tier II Multiply Hourly NOx Estimate by Representative Equilibrium NO2 / NOx Ratio (Current National Default for Annual NAAQS = 0.75) Tier III Detailed Analysis Case-by-Case Basis 21
Current NO2 Screening Procedures in Detail Tier I Total Conversion of NO to NO2 (most conservative 100% conversion) Tier II Ambient Ratio Method (ARM) default of 0.75 likely too high for estimating hourly NO2 conversion. Requires source oriented NO2 and NOx monitoring to develop a more site specific and representative hourly NO2 to NOx conversion ratio Data unavailable in many cases to derive representative ratio Tier III: Several alternative methods currently implemented in AERMOD model Ozone Limiting Method (OLM) limits amount of NO2 conversion by available ambient ozone Plume Molar Volume Ratio Method (PVMRM) limits conversion of NO2 by amount of ambient ozone that is able to mix into the NOx plume on an hourly basis 22
NO2 Experiences: Discussion Gain input from participants of their understanding and experiences thus far in terms of permit modeling for NO2 Issues Concerns Areas of needs Thoughts on process Potential efforts to improve things? BREAK 23
PM NAAQS: Status In 2006, EPA strengthened the 24-hour fine particle standard from the 1997 level of 65 micrograms per cubic meter (μg/m3) to 35μg/m3, and retained the current annual fine particle standard at 15μg/m3. The Agency also retained the existing national 24-hour PM10 standard of 150μg/m3. EPA is currently reviewing the PM2.5 NAAQS Proposal in November 2010 Final rule in July 2011 24
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PM10 Surrogate Policy Status Pursuant to case law re surrogacy, EPA has required that sources demonstrate that PM10 is an adequate surrogate for PM2.5 for that specific application This EPA position was articulated in the LG&E Order and essentially required that the source either submit a demonstration of the adequacy of surrogacy or a PM2.5 NAAQS compliance demonstration. EPA has proposed to repeal the grandfathering provision for federal permits and end the surrogate policy early for SIP-approved States 2/11/2010 NPRM to repeal grandfather provision (allowed continued use of PM 10 Surrogate Policy for grandfathered sources) Administrative stay of grandfather provision (6-1-2009 to 9-1-2009) Second stay (via rulemaking) on grandfather provision (9-22-2009 to 6-22-2010) 26
Status of EPA Rulemaking: PM 2.5 Increments, SILs & SMC Proposed on September 21, 2007 Final rule package cleared OMB review Estimated promulgation date is 06/2010 27 27
PM2.5 Permit Modeling Guidance: Background August 2009 Administrative Order on LG&E essentially established two paths forward in addressing PM2.5 for permits Demonstrate adequacy of PM10 surrogacy policy for PM2.5 Conduct PM2.5 modeling March 23, 2010 Page Memorandum provides: Clarifications on demonstrating the appropriateness of PM10 surrogacy policy to comply with PM2.5 NAAQS Provides recommended modeling procedures for two main stages in PSD ambient impact analysis, i.e., Significant Impact Analysis and Cumulative Impact Analysis 28
PM2.5 Modeling Analysis: It s Simply Different Differences in nature of PM2.5 from other criteria pollutants and the form of the daily NAAQS standard means that standard modeling practices may not be appropriate Recognizing this and associated technical difficulties, PSD modeling for PM2.5 should be viewed as screening-level analysis similar to Appendix W approach for NO2 (Section 5.2.4) 29
PM2.5 Composition in Urban Areas 30
13 Urban/Rural Site Pairings 31
Regional & Local Contributions to Urban PM2.5 32
Local/Regional Contribution by PM2.5 Species 33
National map of urban excess by component for 13 areas 34
PM2.5 Mass (ug/m3) 70 60 50 40 30 20 10 0 Daily PM2.5 Mass Birmingham, AL 2003 2003 Annual Avg: 17.9 ug/m3 08/25/2003 04/15/2003 11/14/2003 09/09/2003 06/23/2003 04/30/2003 06/26/2003 11/02/2003 09/18/2003 09/12/2003 05/24/2003 08/19/2003 09/24/2003 10/06/2003 08/10/2003 10/24/2003 09/06/2003 06/02/2003 12/08/2003 02/26/2003 02/20/2003 03/24/2003 10/21/2003 04/03/2003 03/07/2003 12/26/2003 07/26/2003 04/27/2003 10/09/2003 06/05/2003 08/28/2003 04/12/2003 07/17/2003 08/16/2003 11/20/2003 09/21/2003 05/30/2003 10/03/2003 05/27/2003 04/18/2003 04/24/2003 08/22/2003 08/07/2003 06/08/2003 02/02/2003 06/29/2003 05/03/2003 07/29/2003 05/21/2003 01/09/2003 05/15/2003 08/01/2003 01/30/2003 11/17/2003 02/11/2003 02/14/2003 03/16/2003 06/20/2003 10/18/2003 09/30/2003 03/13/2003 08/04/2003 11/26/2003 10/15/2003 10/30/2003 07/23/2003 05/06/2003 03/22/2003 01/15/2003 06/17/2003 09/03/2003 01/27/2003 07/11/2003 03/04/2003 12/02/2003 07/05/2003 12/20/2003 07/08/2003 10/12/2003 06/11/2003 04/09/2003 07/20/2003 05/09/2003 01/21/2003 10/27/2003 11/05/2003 11/11/2003 12/11/2003 03/31/2003 08/31/2003 04/06/2003 02/17/2003 11/23/2003 07/14/2003 09/27/2003 03/10/2003 03/28/2003 04/21/2003 01/06/2003 07/02/2003 01/03/2003 11/29/2003 03/19/2003 09/15/2003 01/24/2003 02/23/2003 11/08/2003 12/23/2003 12/14/2003 01/18/2003 05/18/2003 12/05/2003 12/29/2003 02/05/2003 02/08/2003 05/12/2003 08/13/2003 06/14/2003 12/17/2003 01/12/2003 Dirtiest Day 2003 5.5% Avg of 15 dirtiest days 7.4% Avg of Intermediate days 7.5% Avg. of 15 cleanest 6.7% days 34.6% 33.3% 39.2% 37.5% 55.1% 41.3% 49.2% 48.4% 1.9% 4.2% 9.4% 18.7% SulfatesNitratesTCMCrustalFRM MassBirmingham 2003 Dirtiest Day in 2003 21.40.714.52.146.6 Dirtiest 15 Avg 12.11.315.22.335.4 Intermediate Avg 5.51.57.71.216.6 Cleanest 15 Avg 2.51.43.10.57.5 Annual Average 2003 6.0 1.4 8.1 1.3 17.9 35
Technical Elements of PM2.5 Permit Modeling Modeling Inventory Develop an emissions inventory of background sources to be included in modeling analysis using traditional guidance Dispersion Modeling Use AERMOD as the EPA Preferred Model for permit modeling to account for primary emissions from project sources & nearby sources, as appropriate Background Concentrations Determine representative background concentration and use DV metrics for annual and daily PM2.5 stds Accounts for majority of secondarily formed PM2.5 (to be determined extent to which account for project s contribution by its precursor emissions) 36
Comparison to SIL and NAAQS Significant Impact Analysis For 5 years of NWS met data, use highest average of modeled annual averages and average of first highest 24-hr average Cumulative Impact Analysis NAAQS 1 st Tier: Combine background as DV metric with modeled result (based on same procedure for SIL comparison) NAAQS 2 nd Tier (for daily): where modeled PM2.5 emissions are not temporally correlated with background PM2.5 levels then combine on a seasonal or quarterly basis NAAQS 3 rd Tier (for daily): consider more temporal and spatial pairing to determine better basis 37
Preliminary Analysis: Simulation of a PSD modeling effort based on Clairton, PA 38
Preliminary Results for Individual Years Example PM 24 Hour Data: Clairton, Pa Year Source H2 Bkg H2 Truth H2 Tier X Tier 1 Bkg H2 + Bkg H2 + Src H2 Src H1 2001 43.0 44.5 90.2 87.5 98.6 2002 25.9 50.4 59.9 76.3 80.4 2003 31.3 46.0 66.6 77.3 92.7 2004 30.9 39.8 68.5 70.7 97.1 2005 43.5 30.9 83.1 74.4 92.3 2006 22.5 35.8 50.7 58.3 62.0 2007 30.3 35.0 47.3 65.3 72.6 2008 19.4 34.6 45.1 54.0 67.1 2009 40.8 25.9 55.7 66.7 90.0 Note: H2 (second highest values) estimates the 98th percentile. Tier 2 not calculated for individual years -- only for five year aggregates 39
Results for 3-year Design Values (Background Data Taken from Most Recent of 5 Years Used for Source Impact) Example PM 24 Hour Data: Clairton, Pa Period Source H2 Bkg H2 Truth H2 Tier X Tier 1 Tier 2 (5 year avg) (3 year avg) (3 year avg) Bgk H2 + Bkg H2 + Bkg H2 + Src H1 Src H2 Src H1 within quarter y2001_2005 34.9 47.0 72.2 81.9 92.2 72.6 y2002_2006 30.8 45.4 65.0 76.2 84.9 67.1 y2003_2007 31.7 38.9 72.7 70.6 83.3 64.5 y2004_2008 29.3 35.5 67.4 64.8 78.2 60.2 y2005_2009 31.3 33.9 60.4 65.2 76.8 58.9 40
PM2.5 Activities and Plans PM2.5 rule on SILs, SMCs, Increment Final rule in June 2010 (currently at OMB) OTAQ PM2.5 Hot-spot modeling guidance for conformity End of May: Publish FR notice announcing 45-day comment period and post draft guidance on OTAQ website Early Fall 2010: Publish FR notice announcing final guidance release EPA-NACAA PM2.5 Modeling Workgroup to gain input on: Development of emissions inventories Determination of Representative background Accounting for secondary formation from project source Subgroup recommendations due end of Sept 2010 41
Planned next steps Develop draft PM2.5 permit modeling guidance by this Fall Host workshop to gain input on draft guidance Fall 2010 in???? Issue final PM2.5 permit modeling guidance by end of year or early 2011 PLEASE NOTE: PM2.5 modeling for permits will continue so seek technical input from OAQPS and vet technical issues through the Model Clearinghouse 42