Technical Support Document (TSD)

For the Modeling and Weight of Evidence (WOE) Portions of the Document Entitled “ Revision to the Allegheny Count y Portion of the Pennsylvania State Implementation Plan Attainment Demonstration for the Liberty - Clairton PM2 .5 Nonattainment Area” April 2011

TSD Prepared October 2011 Timothy A. Leon Guerrero Office of Air Monitoring & Anal ys is, 3AP40 U.S. Environmental Protection Agency , Region 3

1650 Arch Street Philadelphia, Pennsylvania 19103

/s/

___________________

_________________________ Reviewed b y Andrew Hass, Acting Associate Director Office of Air Monitoring & Anal ys is (3AP40)

October 24, 2011

_________________ Date SignedEPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 2 of 16 **Purpose of the Technical Support Document** This Technical Support Doc ument ( TSD ) describes the Environmental Protection Agency ’s (EPA’s) evaluation of the modeling and W e ight - of - Evidence (W OE ) portions of Pennsylvania ’s State Implementation Plan (SIP) entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonatta inment Area ” . The Libert y - Clairton , PA PM - 2.5 nonattainment area is comprised of a small portion of Alleghen y County that includes the boroughs of Glassport, L iberty , L incoln, Port Vue, and the C ity

of Clairton (see figure below) . The area was designated as nonattainment for the 1997 PM - 2.5 National Ambient Air Quality Standard (NAAQS) in the January 5, 2005 Federal Register [70 FR 944], effective April 5, 2005.

EPA requires s tates with nonattainment areas t o submit an attainment d emonstration and as sociated air - qualit y modeling, adopted s tate regulations to reduce emissions of PM - 2.5 and its precursors, and other supporting information demonstrating that the area will attain the standards as expeditiously as practica l . The Alleghen y Count y HealthEPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 3 of 16 Department (ACHD) prepared its PM - 2.5 SIP in cooperation with the Pennsylvania Department of Environmental Protection to comply with the CAAA of 1990 and with EPA requirements for the nonattainment area as stated in EPA’s 2005 designation of the PM - 2.5 nonattainment area and EPA’s Clean Air Fine Particle Implementation Rule [72 FR 20586, 25APR2007]. The purpose of this TSD is to provide more detailed information than can be contained in the official notice published in the Federal Register. Readers who need more information than we provide in this TSD or want to review the modeling should consult the ACHD’s Revision to the Allegheny County Portion of the Pennsylvania State Implementation Plan (April 2011) for the Liberty - Clairton, PA PM - 2.5 nonattainment are a. **The Regulatory Framework** EPA established the PM - 2.5 NAAQS on July 18, 1997 (62 FR 36852). This included an annual PM - 2.5 standard of 15.0 μg/m 3 based on an annual arithmetic mean, averaged over 3 years, and a 24 - hour (or dail y) standard of 65 μg/m 3 b ased on a 3 - ye ar average of the 98th percentile of 24 - hour concentrations. These standards were decided upon after reviewing numerous health studies demonstrating that serious health effects are associated with exposures to PM - 2.5. Following promulgation of a new or revised NAAQS, EPA is required b y the CAA to designate areas throughout the United States as attaining or not attainin g the NAAQS. T his designation process is described in section 107(d)(1) of the CAA. In 1999, EPA and state air - qualit y agenc ies initiated the monitoring process for the 1997 PM - 2.5 NAAQS, and, by January 2001, established a complete set of air - qualit y monitors. On January 5, 2005, EPA published initial air - quality designations for the 1997 PM - 2.5 NAAQS (70 FR 944), based on air - quality monitoring data for calendar years 2001 - 03. The nonattainment designation for an area starts the process whereb y a s tate or tribe must develop an implementation plan that includes, among other things, a demonstration showing how it will attain th e ambient standards by the attainment dates required in the CAA. Under section 172(b), s tates have up to three ye ars after the EPA’s final designations to submit their SIPs to EPA. These SIPs were due on April 5, 2008, three ye ars from the effective date of the designations. Section 172(a)(2) of the Act requires s tates to attain the standards as expeditiously as practicable but within 5 years of designation (i.e. attainment date of April 5, 2010 based on air quality

data for 2007

– 09), or within up to 10 ye ars of designation (i.e. to April 2015) if the EPA Administrator extends an area’s attainment date b y 1

– 5 years based upon the severity of the nonattainment problem or the feasibility of implementing control measures.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 4 of 16 **Introduction to the Liberty**  **- Clair**  **ton, PA PM**  **- 2.5**  **State Implementation Plan** Pennsylvania ’s SIP for the Libert y - Clairton, PA PM - 2.5 nonattainment area outline s plans to reduce emissions that contribute to PM - 2.5 nonattainment. The SIP includes a modeling demonstration that is used to show that the Libert y - Clairton area will meet the 1997 annual PM - 2.5 standard as expeditiously as p ractical . The Liberty - Clairton nonattainment area has some of the highest annual and 24 - hour design values in the United States. This TSD reviews the modeling and WOE portions of Pennsylvania ’s SIP for the Libert y - Clairton, PA PM - 2.5 nonattainment area . Pennsylvania ’s PM - 2.5 SIP includes a modeling demonstration that shows that the Liberty - Clairton area will comply with the annual PM - 2.5 standard as expeditious ly as p ractical . The modeling demonstration consists of results from the Community Multiscale Air Quality (CMAQ) Model coupled with a local - scale modeling anal ys is using EPA’s CALPUFF model . Pennsylvania and the ACHD believe the results from the modeling analy sis as well as the WOE supplemental anal ys es present overwhelming evidence that the Libert y - Clairton, PA PM - 2.5 nonattainment area will attain the 1997 annual PM - 2.5 NAAQS by 201 5, which is as expeditiously as p ractical considering the area’s elevate d base year design values . Model b ase year design values (2000 - 02) were 21.4 μg/m 3 for the annual NAAQS and 63 μg/m 3 24 - hour NAAQ at the Liberty monitor. **What Are The Components Of A Modeled Attainment Demonstration? Modeling Process Overview**  EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze (2007) describes how to construct a model attainment demonstration. The air quality modeling used in the Liberty - Clairton area’s attainment demonstration consisted of two components ; a regional photochemical grid mode l and a local - scale model with sufficient resolution to ex amine the impacts of local emission sources. M odel result s we re used in a “relative ” rather than “absolute” sense. Following this methodology the ratio of the model’s future to current (baseline) predictions at both of the nonattainment area’s PM - 2.5 mon itors determines if the Liberty - Clairton SIP’s proposed local and regional emission controls are likel y to lead to compliance with the 1997 PM - 2.5 NAAQS. The L ibert y - Clairton mod eling demonstration used a regional photochemical grid m odel (CMAQ) for part of its modeling demonstration. B aseline and future CMAQ modeling scenarios were run b y the Bureau of Air Quality Analysis and Research Division of Air Resources New York State Department of Environmental Conservation with emissions information compiled by the Mid - Atlantic/Northeast Visibility Union Regional Planning Organization ( MANE - VU ). CMAQ provided results for the chemicall y reactive PM - 2.5 species such as sulfates and nitrates.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 5 of 16 Local sources in the L iberty - Clairton nonattainment area create steep gradients in the PM - 2.5 concentrations. These gradients cannot be properl y resolved in CMAQ whose mo del grid cells are roughly twelve square kilometers. L ocal scale meteorology is also not well simulated by

the regional model due to steep topography withi n the nonattainment area that often contributes to strong temperature inversions and complex flow patterns within the valley s. A local - scale model, CALPUFF, was used in the attainment demonstration to better gauge the local impacts of direct PM - 2.5 emissio n s and provide some meteorological enhancements within the nonattainment area. ACHD was responsible for running CALPUFF. **Steps Required in a Modeled Attainment Demonstration** EPA guidance 1 encourages states to take certain steps when preparing a modeling anal ys is to demonstrate attainment of the PM - 2.5 NAAQS. Recommendations include the following nine steps: 1) Formulate a conceptual description of an area’s nonattainment problem. 2) Develop a modeling/analysis protocol. 3) Select an appropriate air quality mod el to use. 4) Select appropriate meteorological episodes to model. 5) Choose a modeling domain with appropriate horizontal and vertical resolution and establish the initial and boundary conditions to be used. 6) Generate meteorological and air quality inputs to the air quality model. 7) Generate emissions inputs to the air quality model. 8) Evaluate performance of the air quality model and perform diagnostic tests, as necessary . 9) Perform future year modeling (including additional control strategies, if necessary) and appl y the attainment test. **How Did Allegheny County**  **Address All of the Modeled Attainment Demonstration Components?**  ACHD’s PM - 2.5 SIP for the Libert y - Clairton, PA PM - 2.5 nonattainment area addresse d all of the modeled attainment demonstration elements. Each of these elements will be discuss ed in the following sections. **Conceptual Description of the Problem** "Particulate matter," also known as particle pollution or PM, is a complex mixture of extremely small particles and liquid droplets. Particle pollution is made up of a number

1 See section 10.0 of EPA’s Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze Attainment of Air Quality Goals for Ozone, PM2.5, and Regional Haze , April 2007 ( EPA - 454/B - 07 - 002 )EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 6 of 16 of components, including acids (such as nitrates and sulfates), organic chemicals, metals, and soil or dust particles. Particle pollution exposure is linked to a variety of health problems, including increased respiratory s ymptoms, such as irritation of the airways, co ughing, or difficulty breathing, decreased lung function, aggravated asthma, de velopment of chronic bronchitis, irregular heartbeat, nonfatal heart attacks, and premature death in people with heart or lung disease. ACH D’s conceptual description of its PM - 2.5 nonattainment problem is detailed in Appendix C (Modeling Protocol) o f its SIP document. Two additional reports prepared by the ACHD are included in Appendix E present data from two speciated PM - 2.5 monitors in All eghen y C ounty . The L ibert y - Clairton Area is made up of complex river valley terrain encompassing an area rough ly

three b y five miles in size . Itincludes a four mile winding portion of the Monongahela River south of the City of Pittsburgh and is bordered on the east by the Youghioghen y River. The area includes rural land interspersed with dens ely populated residential areas and industrial facilities. There are significant differences in terrain elevations within the nonattainment area ; river valley elevations averag e just over 700 feet above mean sea level while adjacent hilltops can rise up to 1250 feet. Under weak s ynoptic forcing these sharp elevation differences can generate strong nocturnal temperature inversions . T emperature differences between th e valley floors and nearby

hilltops can range from 2 to 7° F under these conditions . Cold air drainage flows often occur during these periods of s trong nocturnal cooling . Under these circumstances air flows within the valley s can become quite complex with down slope flows reaching 3 - 4 mph and wind directions veering up to 180° within each valley ’ s vertical profile . Episodes of poor air quality often occur within the L iberty - Clairton , PA PM - 2.5 nonattainment area during periods of s trong n octurnal inver sions . Under these conditions , air dispersion is often minimized allowing emissions to “build up” within the river valley s contributing to episodes of poor air quality , which lead to the nonattainment area ’ s high PM - 2.5 design values . On some occasions P M - 2.5 concentrations with in the Liberty - Clairton area are significantl y higher than concentrations in the nearby City of Pittsburgh. These differences in air quality are one of the reasons why the Liberty Clairton, PA PM - 2.5 nonattainment area was separat ed from the surrounding Pittsburgh Beaver Valley , PA PM - 2.5 nonattainment area. ACHD performed source apportionment modeling for the Liberty and Lawrencevi lle monitors in Alleghen y C ounty using the Positive Matrix Factorization Model (PMF Version 1.1). The monitors are approximately eleven miles apart from each other with the Libert y monitor located in the L ibert y - Clairton area and the Lawrenceville monitor located to the north near Pittsburgh .EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 7 of 16 Local impacts were g auged by comparing both monitor s ’ spec iation data with each other using PMF. ACHD’s analy sis found that the Liberty monitor’s PM - 2.5 concentrations are impacted by

regional loading (mainl y sulfates) based on similarities in both monitor’s speciation data . Sources near the Libert y monitor, bo th stationary and mobile, were thought to be responsible for the speciation differences observed between two Allegheny County monitors . On peak concentration day s at Liberty , c arbons and ammonium are prominent s pecies while c horine is more prominent on co ld - weather peak day s. **Model s**  **Used in the Attainment Demonstration** ACHD utilized two models in its attainment demonstration; a regional photochemical grid model used to simulate regional PM - 2.5 concentrations and a local scale model used to simulate the e ffects of local sources of dir ect PM - 2.5 emissions. The photochemical grid model used in ACHD’s modeling demonstration is the CMAQ (version 4.5.1) model with CB4 chemistry , aerosol module for PM - 2.5 and RADM cloud scheme. Photochemical modeling was perfo rmed by the Bureau of Air Quality Anal ys is and Research, New York State Department of Environmental Conservation (DEC) . The CMAQ modeling s ystem has been designed to approach air quality as a whole b y including state - of

- the - science capabilities for modeli ng multiple air quality issues, including tropospheric ozone, fine particles, toxics, acid deposition, and visibility degradation. This s ys tem includes input from both meteorological and emissions models, which are detailed in the following sections. E PA recommends using air - qualit y models such as CMAQ in a “relative” rather than “absolute” sense. That is, take the ratio of the model’s future to current (baseline) predictions at each monitor within the nonattainment area using relative response factors (RRF), a ratio of model projected concentrations over model base - line concentrations. Future PM - 2.5 concentrations are estimated at existing monitor sites by multiplying the modeled relative response factor at locations “near” each monitor by the observation based, monitor - specific, “baseline” design value. The resulting predicted “future concentrations” are then compared to the NAAQS. A CHD’s anal ys is of its PM - 2.5 monitors within Alleghen y Count y showe d significant local impacts in the L iberty - Clairton PM - 2.5 nonattainment area. A more detailed modeling analy sis was ne eded to account for these important local source impacts . As noted previously , atmospheric circulation in the L iberty - Clairton area during periods of high PM - 2.5 concentrations is quite c omplex and beyond the resolution capabilities of most regional photochemical model s , which ty pically contain model grid cells on the order of twelve square kilometers. Additionally , r egional scale photochemical models are unable to fully

resolve important local topographic features that influence emission dispersion. Important spatial relationships between local sources and the affected monitors within the L iberty - Clairton , PA PM - 2.5 nonattainment area are also notEPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 8 of 16 properl y resolved in the regional photoc hemical grid model. For these reasons, ACHD decided to do local scale modeling using EPA’s CALPUFF modeling s ys tem to help better resolve local atmospheric circulation, local terrain features and local emission source contributions. The CALPUFF modeling sy stem was used to create near - field and some lon g range transport simulations for the L ibert y - Clairton area. CALPUFF Version 5.8 (dated June 29, 2007) is the m ost recent EPA - approved version for regulatory applications. CALPUFF is currentl y not EPA’s pref erred near - field model to use for sources within 50 kilometers of the affected monitor (see August 14, 2008 EPA Clarification Memo entitled “ Clarification of Regulator Status of CALPUFF for Near- field Applications” ). The use of CALPUFF in this SIP, howeve r, was granted since the modeling protocol outlining the modeling methodology

was established before the issuance of this EPA memorandum. The CALPUFF modeling sy stem is comprised of CALMET (meteorological model), CALPUFF (dispersion model), geophy sical data preprocessors, meteorological data preprocessors, and several postprocessors such as CALPOST. The CALPro GUI (dated June 29, 2007) comprises CALPUFF and associated preprocessors and postprocessors in a central interface and w as utilized for th e near fi eld modeling anal ys is . ACHD followed modeling procedures outlined in its PM - 2.5 Model Protocol (Appendix C) for the Liberty - Clairton , P A PM - 2.5 n onattainment area and EPA ’s modeling guidance . T he modeling anal ys is utilized a combination of regional CMAQ modeling using the MANE - VU inventory and local CALPUFF modeling using a local revised ACHD inventory (for direct PM - 2.5 emissions only) . ACHD listed several deviations from its original modeling protocol in section 7.1.1 of its main SIP document. These w ere necessary

to account for several issues that came up during the modeling demonstration. ACHD’s modeling methodology for its attainment demonstration followed roughl y the same methodology

used in the Philadelphia Air Toxics study . Average impacts from the uncorrected MANE - VU inventory across an “equivalent grid” were subtracted from the CMAQ impacts on a concurrent basis. The corrected ACHD inventory impacts for Liberty and Clairton were then added to the CMAQ results . **Meteorological Time Periods Use d in the Modeling**  The EPA’s 2007 Modeling Guidance recommends modeling an entire ye ar or, at a minimum, several days in each quarter of a year, to adequatel y represent the range of meteorological conditions that contribute to elevated lev els of fine parti culate matter. MANE - VU regional modeling efforts were based on a base year of 2002. This was the ye ar used for all PM - 2.5 modeling efforts in EPA’s R egion 3 and was also used in the modeling demonstration submitted for the L ibert y - Clairton , PA PM - 2.5 non attainment area.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 9 of 16 **Meteorological Model**  **s Used in the Air Quality Model**  Meteorological data for the regional photochemical grid model and local scale model were constructed for the modeling demonstration. The regional photochemical grid model was driven b y output from the Pennsylvania State Universit y/ National Center for Atmospheric Research (PSU/NCAR) Mesoscale Meteorological Model, also known as MM5. The meteorological model for the local scale modeling was derived using CALMET, which used a combination of MM5 data coupled with local observations from nearb y met station s . The MM5 simulation included “nudging” , which uses observations in the tendency

equations to force the model solution closer to observed values. Additional information regarding the MM5 set up can be found in Appendix K - 2 of ACHD’s SIP document. The following is a short list of MM5 options used in the modeling demonstration simulation:

 Kain - Fritsch (1993 ) convective scheme for both 36 and 12 km domains with some adjustments to correct diurnal phase shifts in surface winds and temperatures  Explicit moisture scheme (without the mixed phase) containing prognostic equations for cloud water (ice) and rainwater (snow)  Modified version of the Blackadar PBL scheme  Simple radiative cooling schem e  Multi - layer soil model to predict land surface temperatures using the surface energy budget equation MM5 met data was also used in the near field analy sis using CALPUFF though the CALMET processor. CALMET was initialized with MM5 met fields and supple mented with meteorological data from the L ibert y monitoring site, the Alleghen y C ounty Airport and USX Clairton. The CALMET processor is used to try and recreate some of the more complex atmospheric flows in the L iberty - Clairton nonattainment area that cannot be resolved in the MM5 simulation. Further details of the meteorological data processing for CALMET can be found in Appendix D of ACHD’s SIP document. **Model Domain, Horizontal/Vertical Resolution and the Initial and Boundary Conditions**  MM5 (version 3.6) was run by the University

of Maryland in consultation with New York DEC staff. The model was applied using a Lambert conformal map projection. The two nested domain consisted of coarse (36 km) and fine (12 km) mesh corresponding to 149 x 129 and 17 5 x 175 grids respectivel y. The Lambert projection used in this work followed the Regional Planning Organization (RPO) national domain setup.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 10 of 16 MM5 uses a terrain following σ - coordinate s ys tem with the pressure at each σ - level determined from a reference s tate that is estimated using the hydrostatic equation from a given sea - level pressure and temperature with a standard lapse rate. There are 30 unevenl y spaced σ - levels yielding 29 vertical layers with higher resolution within the planetary boundary

layer ( PBL). The surface layer was set at about 10 m, the level at which surface winds were ty pically observed, and the model top was set at 50 hPa with a radiative top boundary

condition. CMAQ simulations were performed using a one - way nesting approach for a c ontinental simulation at 36 km grid spacing with a finer 12 km grid centered over the eastern portion of the US . Both domains utilize d 22 layers in the vertical extending to about 16 km with 16 layers placed within the lower three kilometers . T he contine ntal CMAQ simulation utilized clean initial conditions with boundary conditions extracted from a GEOS - CHEM global chemical model simulation. The CMAQ 36 km simulation was initiated from December 15, 2001 with the first 15 days used as a spin up period and terminated on December 31, 2002 . RPO emissions data from 2002 was used with corresponding MM5 meteorological fields developed by the University

of Maryland . Hourly boundary

fields for the 12 km CMAQ domain were obtained from the concentration fields gene rated b y the 36 km CMAQ simulation. The 12 km simulations for both base and future year were assigned the boundary conditions based on the 36 km CMAQ simulation with clean initial conditions. A more detailed description of the CMAQ runs can be found in Appendix K - 4 of ACHD’s SIP document. Model resolution for CALPUFF , the near field model , was on a much finer scale than the regional model. CALPUFF grid spacing for the 150 km regional source analy sis domain was one kilometer and 100 meters for the 20 kil ometer local scale analy sis domain . Both CALPUFF runs contained 11 vertical layers spaced within the first three km. More information on ACHD’s CALPUFF settings can be found in Appendix I of ACHD’s SIP document . **Emissions Used in the Air Quality Model s**  Northeastern US e missions inventories for all source classifications were developed by MANE - VU for use in regional analyses and SIPs. Th e MANE - VU emission inventory was originally developed for regional haze but w as also used for ozone and PM - 2.5 modeling efforts in the N ortheast. A report by MARAMA located in Appendix G of the SIP document provides additional details on the regional emission inventories. The year 2002 was used for the baseline emissions inventory and 2014 for the projected inventory for the L iberty - Clairton area. Regional projections utilized on - the - books/on - the way (OTB/W) controls through the 2012 timeframe. Since no additional projections were available at the time, and since Liberty- Clairton controls focus on direct PM - 2.5 emissions ,EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 11 of 16 regional projections for 2012 were used for precursors and non - point PM - 2.5 emissions in combination with local projections for 2014 for stationary point PM - 2.5 emissions. A more detailed inventory was developed by the ACHD for the extended Liberty- Clai rton area a s part of its near scale modeling analysis. This inventory was limited to direct PM - 2.5 emissions and was developed from both the regional MANE - VU inventories and projections along with ACHD ’s inventories for stationary point sources. These e m issions represent “actual” values based on pollutant emission factors and throughputs or capacities of eac h emission source. E mission values do not necessarily represent permitted or “allowable” limits. Regional controls for SO 2 and NO x in the MANE - VU inventory were based on CAIR. On July 6, 2011, EPA finalized a rule that protects the health of millions of Americans b y helping states reduce air pollution and attain clean air standards. This rule, known as the Cross - State Air Pollution Rule (CSAPR or Cross State Rule ) 2 , requires 27 states to significantl y improve air quality by reducing power plant emissions that contribute to ozone and/or fine particle pollution in other states. **Base Case Run Model Performance Evaluation** Model performance evaluations were done for MM5 and the regional CMAQ runs as well as the local scale runs using CALPUFF. Regional model performance was based on matrices outlined in EPA’s Guidance on the use of models and other analyses for demonstrating attainment of air quality goa ls for ozone, PM - 2.5, and regional haze (EPA - 454/B - 07 - 002) and was summarized in Appendix K - 1. NY DEC examined the MM5 output to determine how well the simulation was performing. Onl y meteorological fields from the ozone season (May through September) we re examined. The nudging process used National Weather Service data so as expected the model did relativel y well compared with this data set. Meteorological data from the Clean Air Status and Trends Network or CASTNET was also used to assess model accura cy since this data set was not included in the nudging process. Vertical parameters were also included in the anal ys is as well as cloud cover data, precipitation and simulated calm periods. The meteorological assessment showed that in general, MM5’s perf ormance was reasonable both at the surface and in the vertical. It was therefore concluded that MM5 performed adequatel y and the data could be used in the CMAQ simulations. Regional model evaluation statistics for the entire 2002 simulation were calculat ed over a wide region for PM - 2.5 mass and major species . In general, CMAQ did a reasonable job simulating daily

average PM - 2.5 and SO 4 (sulfate) mass. CMAQ, however, did not appear to be able to reproduce the day- to - day or seasonal variation in other spec ies like

2 http://www.epa.gov/airtransportEPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 12 of 16 NO 3 , OM, EC, or crustal mass. The model appeared to meet model performance criteria for PM - 2.5 reasonabl y well over the Ozone Transport Region (OTR) as a whole but not as well if one focuse d on an emissions - dense, complex urban setting such as th e New York City

area. This finding appears to support ACHD’s local scale modeling efforts for the L ibert y - Clairt on area. ACHD examined CALPUFF’s ability to simulate local monitor concentrations, specificall y the model’s ability to simulate the strong diurnal variations that contribute to the area’s high PM - 2.5 design values. A comparison of CALPUFF hourly averaged modeled and TEOM ( monitor) concentrations showed the local scale modeling generall y provided a better simulation of the strong diurnal contras ts (high overnight concentrations) than did the regional model though the CALPUFF model tended to over predict PM - 2.5 concentrations. This over prediction, however, was not considered a problem since the local scale modeling was used in a relative sense f or attainment demonstration purposes. CALPUFF m odel performance using EPA matrices was judged to be adequate overall with the 2 nd and 3 rd quarters showing better performance than the 1 st and 4 th quarters. **20 14**  **Control Case Modeling and the Modeled Attain ment Test**  The monitored attainment test for PM - 2.5 utilizes both PM - 2.5 and individual PM - 2.5 component species. EPA refers to the attainment test for PM - 2.5 as the Speciated Modeled Attainment Test (SMAT). A separate relative response factor ( RRF ) is c alculated for each PM - 2.5 species. In order to perform the recommended modeled attainment test, it is recommended that s tates divide observed mass concentrations of PM - 2.5 into seven (7) components plus passive mass :

- mass associated with sulfates

- mass as sociated with nitrates

- mass associated with ammonium

- mass associated with organic carbon

- mass associated with elemental carbon

- mass associated with particle bound water

- mass associated with “other” primary inorganic particulate matter

- and passivel y collect ed mass To apply the test, s tates must first run an a ir quality model at least twice to simulate current emissions and to simulate future year emissions. RRF values are then calculated for each PM - 2.5 species. These RRF values are then multiplied by th e base year concentrations for each monitor within the nonattainment area.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 13 of 16 Data analy ses by

Frank 3 have noted that the FRM monitors do not measure the same components and do not retain all of the PM - 2.5 that is measured b y routine speciation samplers. EP A recommends using the sulfate, adjusted nitrate, derived water, inferred carbonaceous material balance approach or SANDWI CH to account for these differences in the SMAT. A more detailed description of this process can be found in EPA’s Guidance on the U

se of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals for Ozone, PM - 2.5, and Regional Haze , EPA - 454/B - 07 - 002 April 2007. ACHD’s modeled attainment test included an additional step to account for the two models used in its anal ys is. The direct PM - 2.5 component was taken from the CALPUFF modeling while CMAQ provided results for the other PM - 2.5 components. The L ibert y - Clairton nonattainment area has two PM - 2.5 monitoring sites , Liberty and Clairton. Speciation data from L ibert y was used for the Clairton monitor since this site does not collect speciation data. Details on how the modeling attainment demonstration was conducted are included in s ection 8 of the main PM - 2.5 SIP document. Projected monitor concentrations were calculated for both monitors in the Liberty Clairton area following EPA guidance. EPA has developed the Modeled Attainment Test Software (MATS) to automatically calculate design values and interpolate for unmonitored areas. T esting of MATS version 2.2.1 show ed inconsistent results with the methodology

given in the EPA Modeling Guidance. EPA’s MATS software, therefore, was not used by

ACHD in this attainment demonstration though the general methodology was followed to calculate the projected PM - 2.5 concentrat ions. **Summary of the Combined Photochemical and CALPUFF**  **Modeling Results** Annual and 24 - hour PM - 2.5 concentrations for both the L iberty and Clairton monitors were calculated from the quarterl y base - ye ar averaged monitor concentrations and the RRF s calculated from CMAQ and CALPUFF for each PM - 2.5 species component s . Results for the annual and 24 - hour PM - 2.5 NAAQS are summarized in the following table and show that the projected 20 14 annual and 24 - hour design value s are below the 1997 PM - 2.5 NAAQ S.

3 Frank, N., 2006: “Retained Nitrate, Hydrated Sulfates, and Carbonaceous Mass in Federal Reference Method Fine Particulate Matter for Six Eastern U.S. Cities” J. Air Waste Mange. Assoc. , 56, 500 - 511.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 14 of 16 **Mode l Projected PM**  **- 2.5 Concentrations**  **For the Liberty -**  **Clairton, PA PM -**  **2.5 Nonattainment Area Monitor**  **Annual Standard 24**  **- Hour Standard** 

**Projected 1997 NAAQS**  **Projected 1997 NAAQS**  Liberty 14.3 μg/m 3 15.0 μg/m 3 42 μg/m 3 65 μg/m 3 Clairton 11.8 μg/m 3 15.0 μg/m 3 27 μg/m 3 65 μg/m 3 EPA’s CSAPR rule was published after ACHD submitted their PM - 2.5 SIP for L iberty Clairton. ACHD did provide an anal ys is of EPA’s Transport Rule, which had replaced EPA’s CAIR regional emission control proposal, in its Weight of Evide nce (WOE) section (13.3). EPA’s Transport Rule was the proposal in effect at the time of the SIP document’s preparation. EPA Region 3 suggests that ACHD submit an addendum to their current SIP document that examines EPA’s most recent regional emission co ntrol proposal (CSAPR) to ensure that its SIP modeling analy sis is at least as controlled as EPA’s current proposal. This addendum should reexamine the elements included in section 13.3 of ACHD’s main SIP document and could additionally include a comparis on of model results for the L ibert y Clairton area from EPA’s CAIR and CSAPR modeling anal ys es . **Local Area Analysis** EPA guidance calls for additional analy ses in areas where large sources of primary particulates could cause substantial spatial gradients i n PM - 2.5 concentrations. These are often referred to as “hot spots”, which could impact an area’s ability to comply

with the NAAQS. Anal ys is of these hot spots could necessitate additional photochemical grid modeling using a finer modeling grid scale, do wn to 1 to 2 kilometers, or alternativel y the use of a Gaussian dispersion mode l . ACHD conducted a local area anal ys is using EPA’s CALPUFF model. This analy sis examined the impacts on direct PM - 2.5 emissions in the L iberty - Clairton, PA nonattainment area . The se impacts were coupled with the regional CMAQ modeling anal ys is to demonstrate that the nonattainment area would comply with the 1997 PM - 2.5 NAAQS. **Unmonitored Area Analys e**  **s** The unmonitored area analy sis is intended to be the primary means for ide ntifying high PM - 2.5 concentrations outside of traditionally monitored locations. The spatial resolution of the model that is the underlying basis of the unmonitored area anal ys is will determine how well it addres ses primary PM - 2.5 hotspot s.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 15 of 16 The size of the L ibert y - Clairton, PA PM - 2.5 nonattainment area is much smaller than most of the neighboring nonattainment areas. As a consequence of its size, the Libert y Clairton, PA PM - 2.5 nonattainment area has a much higher density of monitors within it . This p artially

negates the necessit y of doing this analysis though ACHD detailed an assessment of the area in section 8.6 of its main SIP document. ACHD examined modeled PM - 2.5 reductions in the vicinity of the Libert y monitor. Several large sources of direct PM - 2.5 emissions lie southwest of the monitor near steep terrain adjacent to the Monongahela River. ACHD examined percent reductions in these areas and noted that shutdowns and plant emission reductions would produce much greater improvements in air quali ty in these areas than what are projected to occur at the Liberty monitor itself. **Weight of Evidence Demonstration** ACHD conducted a Weight of Evidence (WOE) demonstration in accordance with s ection 2.3 of EPA’s modeling guidance . The WOE demonstration i s detailed in section 13 of ACHD’s main SIP document . ACHD’s WOE demonstration consisted of an anal ys is of monitor trends, local and national emission control programs, population trends and monitoring concentrations during periods of low production. The se results were used as further evidence supporting the ACHD’s conclusion that their SIP modeling anal ys is demonstrates compliance with the 1997 PM - 2.5 NAAQS. ACHD examined PM - 2.5 monitoring trends within the nonattainment area and the surrounding region. PM - 2.5 concentrations at most of the regional monitors appear to be declining though ACHD noted these trends may not be statistically

significant at this time. ACHD included a summary of various local and regional emission control programs being impleme nted in the area. Some of these control measures may extend beyond the Liberty - Clairton, PA PM - 2.5 nonattainment area and therefore may have a lesser impact. Emission control programs noted in the WOE section include Pennsylvania’s enactment of a wood bo iler rule, a wood stove change out program in southwest Pennsylvania, EPA’s recently

proposed Transport Rule, Allegheny Count y’s diesel fuel engine retrofit program, local and state anti - idling campaigns and Allegheny County ’s grant program to reduce diese l particulate emissions. ACHD contends that the combined effects of these controls add additional support for their attainment demonstration. Recent population trends are declining in the Pittsburgh region. ACHD noted that these population declines , if they continue , would help reduce emissions in the area that contribute to the nonattainment problem; fewer people equate s to less driving and other activities that contribute to emissions in the area.EPA Technical Support Document for the Modeling Portion of Pennsylvania’s

Revi sion to the Allegheny County Portion of the Pennsylvania State Implementation Plan Entitled “ Attainment Demonstration for the Liberty - Clairton PM 2.5 Nonattainment Area ” TSD Prepared October 2011

Page 16 of 16 ACHD also looked at the effect of lower emissions on i ts PM - 2.5 monitoring network during the recent economic downturn. This was done by comparing TEOM data from 2009 , a period of lower production due to the economic downturn, to the unaffected 2000 - 2008 time period. P roduction levels at the local and regio nal level have fallen due to the recent economic downturn . These emission reductions appear to have lower ed monitor concentrations when compared to previous time periods. ACHD interprets these declines as demonstrating the future effectiveness of their p roposed local source emission controls. **Recommendation of Conditional**  **A pproval of**  **Liberty -**  **Clairton PM**  **- 2.5**  **Attainment Demonstration**  EPA has evaluated the information provided in the SIP document as well as other information relevant to assessing air qual ity in the Liberty - Clairton, PA PM - 2.5 nonattainment area . EPA conclude s that attainment of the 1997 PM - 2.5 NAAQS will likely occur b y the proposed attainment date (201 5 ). ACHD ’s projected (modeled) 20 14 design values are expected to be below 15.0 μg/m 3 and 65 μg/m 3 respectively indicating the nonattainment area satisf ies the Clean Air Act’s requirement that S tate Implementation Plans provide for attainment of the NAAQS by the applicable attainment date. As noted previousl y, ACHD’s regio nal CMAQ modeling included emission controls from EPA’s CAIR program. Since ACHD’s SIP submittal, EPA has proposed CSAPR to replace CAIR. To ensure that the modeling demonstration is still valid EPA is requesting that ACHD redo the analy sis it included i n section 13.3 of its main SIP document and consider examin ing the modeling technical support documents for CAIR and the recentl y proposed Cross State Rule to ensure that the more recentl y proposed rule provides at least the same or possibly lower model co ncentrations in the L ibert y - Clairton area as the modeling analy sis used in the April 2011 SIP modeling demonstration . Based on the technical information provided in the Libert y - Clairton SIP document, EPA concludes that the modeling and WOE analy ses demons trate attainment of the 1997 PM 2.5 NAAQS. EPA, therefore, should conditionally approve the model attainment demonstration portion of Liberty - Clairton, PA PM - 2.5 SIP . Final approval of the model attainment demonstration portion of the SIP will be conting ent on ACHD’s re anal ys is of the elements included in section 13.3 of its main SIP document and an examination of modeled PM - 2.5 concentrations from EPA’s proposed CSAPR Rule.