### Appendix B
ALCOA BART MO DELING REPORT

# Site-Specific Modeling for BART Analysis at Alcoa Inc. – Tennessee Operations’ South Plant, Blount County, Tennessee

February 2007

Prepared For:
Alcoa Inc. -Tennessee Operations Blount County, Tennessee

Prepared By:

TRC Environmental Corporation Wannalancit Mills 650 Suffolk Street Lowell, Massachusetts 01854 (978) 970-5600i 

## TABLE OF CONTENTS

Page

LIST OF FIGURES II

1. INTRODUCTION 1-1

2. SOURCE DESCRIPTION 2-1 2.1 

### Initial (b ase case) run 2-1 2.2 Control scenario 2-8

3. GEOPHYSICAL AND METEOROLOGICAL DATA 3-1 3.1 Terrain 3-1 3.2 Land Use 3-2 3.3 Meteorological Data Base 3-6

4. AIR QUALITY MODELING METHODOLOGY 4-1 4.1 Model Selection 4-1 4.1.1 Major Features of CALMET 4-2 4.1.2 Major Features of CALPUFF 4-4 4.2 Modeling Domain 4-9 4.3 Meteorological Modeling Options 4-9 4.4 Dispersion Modeling Options 4-9 4.5 Visibility Calculations 4-11

5. RESULTS 5-1

6. REFERENCES 6-1ii 

## LIST OF FIGURES

Page
Figure 2-1. Aerial photo of the facility with the potrooms and point sources underlined in red. 2-2
Figure 2-2. Aloca South Plant layout in plant coordinates. 2-3
Figure 3-1 Terrain contour (m MSL) at 4 km resolution (VISTAS CALMET Domain 3) use for the screening run. 3-3
Figure 3-2 Terrain contour (m MSL) at 1 km resolution on the 334 km x 259 km CALMET and CALPUFF model domains. 3-4
Figure 3-3. Dominant Land Use categories at 1 km resolution on the 334 km x 259 km CALMET and CALPUFF model domains. 3-5
Figure 3-4 Surface, upper air, MM5 and precipitation st ations to be used in the 2001 modeling.. 3-12
Figure 3-5 Surface, upper air, MM5 and precipitation st ations to be used in the 2002 modeling.. 3-13
Figure 3-6 Surface, upper air, MM5 and precipitation st ations to be used in the 2003 modeling. 3-14
Figure 3-7 Ozone stations, both CASTNet a nd AIRS used in the 2001 modeling. 3-17
Figure 3-8 Ozone stations, both CASTNet a nd AIRS used in the 2002 modeling. 3-18
Figure 3-9 Ozone stations, both CASTNet a nd AIRS used in the 2003 modeling. 3-19iii 

## LIST OF TABLES

Page

Table 2-1. Line Sources and Parameters used in CALPUFF 2-4

Table 2-2. Point Sources and Parameters used in CALPUFF 2-5

Table 2-3. Point and Line Source Emissions. 2-6

Table 2-4. PM 10 

### Speciation Assumptions. 2-7
Table 2-5. Point Sources Added in the Wet Scrubber Scenario to Replace P01 to P04 2-9
Table 2-6. Point Source P15 (SO 2 

### Control Source) Emission Rate. 2-9
Table 3-1. U.S. Geological Survey Land Use and Land Cover Classification System 3-7
Table 3-2. Default CALMET Land Use Categories and Associated Geophysical Parameters Based on the U.S. Geological Survey Land Use Classification System (14-Category System) 3-8
Table 3-3. Meteorological data s ources and parameters available 3-9
Table 3-4. NWS hourly surface stati ons for 2001, 2002 and 2003. 3-10
Table 3-5. Upper air stations used for 2001, 2002 and 2003. 3-10
Table 3-6. Hourly NWS precipitation stations for 2001, 2002 and 2003. 3-11
Table 3-7. Ozone stations for 2001, 2002 and 2003. 3-16
Table 4-1. Major features of the CALMET meteorological model 4-3
Table 4-2. Major Features of the CALPUFF Model. 4-7
Table 4-3. Summary of Natural Background for Soil 4-14
Table 4-4. Monthly Site-Specific f(RH) values based on the Centroid of the Area, for Visibility Method 6 application 4-14
Table 5-1. Results for visibility impact us ing Method 6 – Base case run - year 2001 5-3
Table 5-2. Results for visibility impact using Method 6 –Base case run - year 2002 5-4
Table 5-3. Results for visibility impact using Method 6 –Base case run - year 2003 5-5
Table 5-4. Results for visibility impact using Method 8 –Base case run - year 2001 5-6
Table 5-5. Results for visibility impact using Method 8 –Base case run - year 2002 5-7
Table 5-6. Results for visibility impact using Method 8 –Base case run - year 2003 5-8iv 

### Table 5-7. Results for visibility impact usi ng Method 6 – Wet scrubber scenario - year 2001 5-9
Table 5-8. Results for visibility impact usi ng Method 6 – Wet scrubber scenario - year 2002 5-9
Table 5-9. Results for visibility impact usi ng Method 6 – Wet scrubber scenario - year 2003 5-9
Table 5-10. Results for visibility impact using Method 8 – Wet scrubber scenario - year 2001 5-10
Table 5-11. Results for visibility impact using Method 8 – Wet scrubber scenario - year 2002 5-10
Table 5-12. Results for visibility impact using Method 8 – Wet scrubber scenario - year 2003 5-10
Table 5-13. Summary Table of Compliance at the 98 th 

### percentile change in light extinction for Initial Runs 5-11
Table 5-14. Summary Table of Compliance at the 98 th 

### percentile change in light extinction for the control scenario 5-11
Table 5-15. Base case run – Source group and species contributions at the 8 th 

### Highest light extinction change for Great Smoky Mountains Na tional Park using CALPOST Method 6 5-12
Table 5-16. Base case run – Source group and species contributions at the 8 th 

### Highest light extinction change for Great Smoky Mountains Na tional Park using CALPOST Method 8 5-13Introduction 1-1 

## 1. INTRODUCTION

TRC Environmental Corporation has conducte d site-specific BART (Best Available Retrofit Technology) modeling for Alcoa Inc. – Tennessee Operations’ South Plant. This facility is situated in Blount County , Tennessee in Alcoa City north of Maryville west of the Appalachian Mountains not far from the Tennessee/North Carolina border. The Alcoa South Plant facility is a primary aluminum smelter and secondary aluminum production facility.

On July 6, 2005 the US Environment Protection Agency produced the Federal Register document, 40 CFR Part 51 in order to introduce new National Regional Haze Regulations for Best Available Retrofit Technology. The regional haze rule requires States to submit implementation plans (SIPs) to address regional haze visibility impairment in 156 Federally-protected parks and wilderness areas, commonly referred to as “Class 1 Areas”. The final rule included a requirement for BART for certain large stationary sources that were put in place between 1962 and 1977. The regional haze rule uses the term “BART-eligible source” to describe those sources which have the potential to emit 250 t ons or more of a visibility-impairing air pollutant, were put in place between A ugust 7, 1962 and Augus t 7 1977 and whose operations fall within one or more of 26 specifically listed source categories, of which Primary Aluminum Ore Reduction Plants are one.

BART review is required when the so urce emits any air pollutant which may reasonably be anticipated to cause or contribut e to any impairment of visibility in any Class 1 area. In identifying a level of control of BART, States are required by section 169A(g) of the CAA to consider; (a) the costs of compliance, (b) the energy and non-air quality environmental impacts of compliance, (c) any existing pollution control technology in use at the source, (d ) the remaining useful life of the source and (e) the degree of visibility improvement which may reasonably be anticipated from the use of BART.

The purpose of the modeling is to assess the ambient air quality impacts of sulfur dioxide (SO 2 

### ), particulate matter (PM) and nitrogen oxides (NO x 

### ) emissions and compare the impacts to Significant Impact Levels (SILs) at all the Class I areas located within a radius of 300 km of the facility. A total of six Class I areas are located within this radius: Mammoth Cave National Park , Great Smoky Mountains National Park, Linville Gorge Wilderness Area, Shining Ro ck Wilderness Area, Cohutta Wilderness Area and Joyce-Kilmer/ Slickrock Wilderne ss Area. A screening run on a 4-km resolution domain has determined that there will be no exceedances of a 0.5 deciview screening threshold at the most distant Clas s I area (Mammoth Cave National Park), so this Class I area is not subject to furt her analysis. A set of refined modeling simulations on a high resolution (1-km) grid is conducted in this report to evaluate impacts at the five remaining Class I areas.Introduction 1-2 

### The topography of the screening domain area consisted of gentle rolling terrain on its west side where elevation of the land ranges from ~120m in the southwest to ~ 300m in the north. A much higher elevation terrain crosses the domain from the northeast corner to the center southern portion of the domain. This is the southern part of the Appalachian Mountains, whose peaks can reach 2000 meters. The refined domain is a zoom on the southern part of the Appalachian Mountains including the highest complex terrain areas. As a result, there is a strong potential for terrain effects, both on the meteorological fields and in terms ofplume-terrain interaction effects. A nonsteady-state modeling approach is useful in this assessment to properly evaluate theair quality impacts of the facilty’s sources. The CALMET and CALPUFF nonsteady-state models (Scire et al., 2000a,b) are used in the modeling analysis. The U.S. Environmental Protection Agency (USEPA) has promulgated the CALPUFF modeling system as a Guideline Model for Class I impact assessments and other long range transport applications or near fi eld applications involving complex flows (USEPA, 2000), and the model is recommende d by both the Federal Land Managers Air Quality Workgroup (FLAG, 2000) and the Interagency Workgroup on Air Quality Modeling (IWAQM, 1998). CALPUFF is specifically recommended by the USEPA for BART analyses ( Federal Register , 6 July 2005).

CALMET is a diagnostic meteorological model that produces three-dimensional wind fields based on parameterized treatments of terrain effects such as slope flows and terrain blocking effects. Meteorologi cal observations are used to determine the wind field in areas where the observations are representative. Hourly meteorological data produced by the Mesoscale Model, Vers ion 5 (MM5) on a 12 km grid are used in CALMET for 2001 and 2002 to define the initial guess wind fields before CALMET’s terrain adjustments is computed. For 2003, MM5 fields produced on a 36 km grid are used for the initial guess fields. The CALMET simulations, on a 4- km grid resolution domain (Domain 3) prepared for VISTAS was used in the screening analysis. Because of the proxim ity of the Alcoa facility to the Great Smoky Mountains National Park and the expected terrain influences, a refined simulation on a 1-km grid, is used to better resolve the terrain effects on the wind and pollutant dispersion.

CALPUFF is a non-steady-state puff dispersion model. It accounts for spatial changes in the CALMET-produced meteorological fields, variability in surface conditions (elevation, surface roughness, vegetation type, etc.), chemical transformation, wet removal due to rain and snow, dry depos ition, and terrain influences on plume interaction with the surface. CALPUFF contains a module to compute visibility effects, based on a hu midity-dependent relationship between particulate matter concentrations and light extinction, as well as wet and dry acid deposition fluxes. The screening and refine d meteorological and dispersion modeling simulations were conducted for a three- year period (2001, 2002 and 2003). SO 2 

### , PM, and NO x 

### , emissions and their secondary pr oducts resulting from chemicalIntroduction 1-3 

### conversions from the Alcoa facility are mode led at receptors in the Class I areas and their impacts on visibility are evaluated.

This report outlines the techniques and data sources used in the BART analyses. The screening modeling was conducted in accordan ce with the procedures outlined in the VISTAS modeling protocol, and the 4-km VISTAS Domain 3 was used, even though the proximity of the facility to the closest Class I area. The refined analysis is based on the use of a more detailed terrain using procedures described in this site-specific protocol. In Section 2, a general description of the study area and the source configuration is provided. Descriptions of the site characteristics and the data bases (meteorological, geophysical, and aerometric) used in the analysis are provided in Section 3. Section 4 includes an ove rview of the CALMET and CALPUFF models, and the parameters used in the analysis. Th e results are summarized in Section 5.Source Description 2-1 

## 2. SOURCE DESCRIPTION

2.1 Initial (base case) run

The Alcoa South Plant facility is a primary aluminum smelter and secondary aluminum production facility located in Blount County, Tennessee west of the Appalachian Mountains not far from the Tennessee/North Carolina border.

A BART applicability analysis was comple ted for the facility to determine those sources subject to the BART controls. The BART-eligible sources include two potlines (4 potrooms), an anode bake furnace, an aluminum scrap crusher, a delacquering furnace, and 2 aluminum scrap melting furnaces. Figure 2-1 displays an aerial photo of the facility with the potrooms and point sources subject to BART outlined.

Since the Facility is located less than 50 km away from the Great Smoky Mountains National Park Class I area, downwash is a pplied. The building parameters were computed in a previous study dated December 1999. The building downwash parameters for the Aluminum Reclamation Crusher has been recomputed in this application, since this stack was not modeled in the previous study. It emits PM only. Figure 2-2 displays in plant coordinates the location of the buildings, potrooms and stacks. In this figure, true north is 7 degrees east of plant north shown on the figure.

Table 2-1 lists the line source paramete rs while Table 2-2 shows the source parameters for the point sources. Table 2-3 summarizes the line and point source emission rates for the modeled pollutants and Table 2-4 summarizes the particulate speciation for all the sources. Note that coarse particulates are defined as particulates in the size range of 10 microns to 2.5 microns while fine particulates are equal to or less than 2.5 microns (i.e. PM 2.5 

### ). The particulate matters provided are already in three categories: PM10-PM2.5, solid PM 2.5 

### and organic condensable. For modeling purposes, particulate matter is divided into six size categories: PM800 (6-10μm), PM425 (2.5-6μm), PM187 (2.5-1.24μm), PM112 (1-1.24μm), PM081 (0.62-1μm) and PM056 (0.5-0.62μm). PM 10 

### provided is partitioned the following way:

1- PM10-PM2.5 is half in PM800 and half in PM425 and then added to form PMC – Coarse particulate matter has an extinction efficiency of 0.6.

2- Solid PM2.5 is half in PM081 and half in PM056 and then added to form SOIL – Fine particulate matter has an extinction efficiency of 1.0.

3- Organic Condensable is separated half in PM081 and half in PM056 and then added to form Secondary Organic Ae rosol (SOA) – SOA has an extinction efficiency of 4.0.Source Description 2-2 

### Figure 2-1 . Aerial photo of the facility with the potrooms and point sources in Geographic Coordinates. -83.985 -83.98 -83.975 -83.97 -83.965 -83.96 Longitude (in degree) 35.77 35.775

35.78Latitude (in degree) ALCOA South Plant in Blount County, Alcoa city north of Maryville

Geographic Projection, units: degree (dd) Datum: NAD83Source Description 2-3 

### Figure 2-2 . Alcoa South Plant layout in plant coordinates – North represents the plant north. True north is 7 degrees east of plant north. -400 -200 0 200 Y-East Plant Coordinates (in meters) -600 -400 -200 0 200 400 600 800 1000X-North Plant Coordinates (in meters) 

### Building locations and BART point sources locations in Plant Coordinate

Anode Bake Furnace Aluminum Scrap Crusher Delacquering Furnace
Aluminum scrap Melting Furnaces

2 Lines (4 potrooms)Source Description 2-4Table 2-1. Line Sources and Parameters used in CALPUFFSourceIDEmissionUnit ID #Stack NameReleaseHeight(m)MonitorWidth(m)ExitVelocity(m/s)Delta T (ExitT – Tair)(oK)BeginUTME/N (km)EndingUTME/N (km)BeginLCC E/N(km)EndingLCC E/N(km)L01 TNPOT0045b_1 Potline#1 Room 1 18.57 3.05 1.34 22.5 231.5522,3963.2083231.5770,3962.76181166.7654, -383.20761166.8666, -383.6421L02 TNPOT0045b_2 Potline#1 Room 2 18.57 3.05 1.34 22.5 231.5006,3963.2057231.5257,3962.75941166.7153, -383.2191166.8168, -383.6533L03 TNPOTL2RM_3 Potline#2 Room 3 18.57 3.05 1.34 22.5 231.4504,3963.2030231.4755,3962.75641166.667, -383.231166.768, -383.665L04 TNPOTL2RM_4 Potline#2 Room 4 18.57 3.05 1.34 22.5 231.3988,3963.2006231.4239,3962.75341166.617, -383.2421166.718, -383.677Notes:L01-L04: F’ = 761.6 m4/s3; Ave. line source width = 3.05m; Ave. building dimension =480.67m; H = 18.57m, W = 22.65m;Ave. building separation =28.55mThe Release height (m), Monitorwidth (m), Exit Velocity (m/s) and Exit Temperature (oK) are all taken from the 1999 ALCOA Tennessee studyThe coordinates are displayed inUTM17 NAD27 datum taken from “Stacks_Model_TNBART_Oct2005_rev1.xls” and in Lambert conformal projection in NWS-84, standardparallel 33N, 45N, origin: 40N, 97W (projection of CALMET/CALPUFF run). They show a slight shift from the aerial photo, but are kept as is because the aerial photois not adequate to digitalize all individual stacks.Notes1. Source information from “Stacks_Model_TNBART_Oct2005_rev1.xls”transmitted in the email from Mike Palazzolo to Joe Scire dated May 16, 20062L01-L04: Average Line Source Buoyancy Parameter (F') CalculationF'= [gLWmw(Ts-Ta)]/Ts= 761.6 m4/s3whereg = acceleration of gravity = 9.81 m/s2L = line source length = 480.67 mWm= line source width = 3.05 mw = line source exit velocity = 1.34 m/sTs= line source exit temperature = oKTa= ambient air temperature = oKTs- Ta=ΔT = 22.5 oKSource Description 2-5Table 2-2. Point Sources and Parameters used in CALPUFF.IndexEmissionUnit ID #Stack NameStackHeight(m)StackDiameter(m)ExitVelocity(m/s)ExitTemp(oK)UTMEasting(km)UTMNorthing(km)LCCEasting(km)LCCNorthing(km)P01 TNPOTL0045a_N A398 Line 1 North 15.96 3.82 20.40 382.8 231.536 3963.050 1166.777 -383.366P02 TNPOTP0045a_S A398 Line 1 South 15.96 3.82 20.40 382.8 231.539 3962.923 1166.802 -383.49P03 TNPOTL0048_N A398 Line 2 North 22.60 4.88 10.32 377.5 231.433 3963.049 1166.676 -383.385P04 TNPOTL0048_S A398 Line 2 South 22.60 4.88 10.46 373.5 231.441 3962.916 1166.707 -383.514P05 TNANOD0008_1 Bake Stack #1 22.15 1.22 11.46 347.0 231.421 3962.655 1166.732 -383.774P06 TNANOD0008_2 Bake Stack #2 22.15 1.22 11.46 347.0 231.421 3962.647 1166.734 -383.782P07 TNANOD0008_3 Bake Stack #3 22.15 1.22 11.46 347.0 231.422 3962.639 1166.736 -383.789P08 TNANOD0008_4 Bake Stack #4 22.15 1.22 11.46 347.0 231.422 3962.661 1166.732 -383.768P09 TNANOD0008_5 Bake Stack #5 22.15 1.22 11.46 347.0 231.423 3962.623 1166.74 -383.805P10 TNANOD0008_6 Bake Stack #6 22.15 1.22 11.46 347.0 231.423 3962.615 1166.741 -383.813P11 TNCRSH0208 Aluminum ReclamationCrusher18.29 1.22 12.62 295.4 231.300 3963.700 1166.434 -382.768P12 TNDFRN0201 Aluminum ReclamationDelacquering Furnace #122.86 1.45 16.10 1155.4 231.315 3963.657 1166.456 -382.808P13 TNMFRN0203 Aluminum ReclamationMelting Furnace #120.73 1.92 10.46 524.3 231.316 3963.617 1166.464 -382.847P14 TNMFRN0204 Aluminum ReclamationMelting Furnace #220.73 1.83 18.11 711.5 231.282 3963.615 1166.431 -382.854Note: UTM 17 Coordinates correspond to a datum ofNAD27; LCC coordinates are in datum NWS-84.Note 2: Exit velocity for Aluminum Reclamation Delacquering Furnace has been updatedto 16.10 m/s according to new spreadsheet“Stacks_Model_TN BART_October2006.xls”received by Joe Scire on October 24, 2006.Source Description 2-6Table 2-3. Point and Line Source Emissions.SourceIDEmissionUnit ID #Stack NamePM10-PM2.5g/sSolidPM2.5g/sOrg. Condensablesg/sSO2g/sNOxg/sL01 TNPOT0045b_1 Potline#1 Room1 0.825 1.163 1.110 0.457 0.002L02 TNPOT0045b_2 Potline#1 Room2 0.825 1.163 1.100 0.457 0.002L03 TNPOTL2RM_3 Potline#2 Room 3 0.722 1.018 0.972 0.457 0.001L04 TNPOTL2RM_4 Potline#2 Room 4 0.722 1.018 0.972 0.457 0.001P01 TNPOTL0045a_N A398 Line 1North 0.024 0.013 0.200 30.0 0.163P02 TNPOTP0045a_S A398 Line 1South 0.024 0.013 0.200 30.0 0.163P03 TNPOTL0048_N A398 Line 2North 0.090 0.048 0.745 30.0 0.087P04 TNPOTL0048_S A398 Line 2South 0.090 0.048 0.745 30.0 0.087P05 TNANOD0008_1 Bake Stack#1 0.008 0.005 0.047 3.11 0.399P06 TNANOD0008_2 Bake Stack#2 0.008 0.005 0.047 3.11 0.399P07 TNANOD0008_3 Bake Stack#3 0.008 0.005 0.047 3.11 0.399P08 TNANOD0008_4 Bake Stack#4 0.008 0.005 0.047 3.11 0.399P09 TNANOD0008_5 Bake Stack#5 0.008 0.005 0.047 3.11 0.399P10 TNANOD0008_6 Bake Stack#6 0.008 0.005 0.047 3.11 0.399P11 TNCRSH0208 Aluminum Reclamation Crusher 0.097 0 0 0 0P12 TNDFRN0201Aluminum ReclamationDelacquering Furnace #10.045 0.027 0.001 0.087 1.358P13 TNMFRN0203Aluminum ReclamationMelting Furnace #10.128 0.076 0.002 0.003 0.214P14 TNMFRN0204Aluminum ReclamationMelting Furnace #20.137 0.081 0.002 0.004 0.228Note: Emission rates from Excel Spreadsheet “Stacks_model_TNBART_December2006R1.xls” sent to Joe Scire on December 21, 2006Source Description 2-7Table 2-4. PM10Speciation Assumptions.Coarse Filterable PMFine Filterable PMCondensable PMFilterable+CondensableSourceIDCoarseFilterablePMFineFilterablePMCondensablePMTotal(Filterable+Cond) PM6-10μm2.5-6μm1.25-2.5μm1.00-1.25μm0.625-1.00μm0.500-0.625μm0.625-1.00μm0.500-0.625μm0.625-1.00μm0.500-0.625μm(g/s) (g/s) (g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)(g/s)L010.825 1.163 1.1103.0980.41250.4125000.58150.58150.5550.5551.13651.1365L020.825 1.163 1.1103.0980.41250.4125000.58150.58150.5550.5551.13651.1365L030.722 1.018 0.9722.7120.3610.361000.5090.5090.4860.4860.9950.995L040.722 1.018 0.9722.7120.3610.361000.5090.5090.4860.4860.9950.995P010.024 0.013 0.2000.2370.0120.012000.00650.00650.1000.1000.10650.1065P020.024 0.013 0.2000.2370.0120.012000.00650.00650.1000.1000.10650.1065P030.090 0.048 0.7450.8830.0450.045000.0240.0240.37250.37250.39650.3965P040.090 0.048 0.7450.8830.0450.045000.0240.0240.37250.37250.39650.3965P050.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P060.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P070.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P080.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P090.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P100.008 0.005 0.0470.060.0040.004000.00250.00250.02350.02350.0260.026P110.097 0 00.0970.04850.048500000000P120.045 0.027 0.0010.0730.02250.0225000.01350.01350.00050.00050.0140.014P130.128 0.076 0.0020.2060.0640.064000.0380.0380.0010.0010.0390.039P140.137 0.081 0.0020.2200.06850.0685000.04050.04050.0010.0010.04150.0415Note: Emission rates from Excel Spreadsheet “Stacks_model_TNBART_December2006R1.xls” sent to Joe Scire on December 21, 2006Source Description 2-8 

### 2.2 Control scenario

A control scenario is evaluated in this anal ysis for the Class I areas showing an exceedance of the light extinction exemption threshold of 0.5 deciviews in the initial run. The control run uses wet scrubbers. The four A398 stacks are replaced by one P15 stack (see Tables 2- 5 and 2-6) which has wet scrubbers for SO 2 

### control. Particulate matter is treated in a similar way as in the initial run.Source Description 2-9Table 2-5. Point Sources Added in the Wet Scrubber Scenario to Replace P01 to P04, the Four A398 Stacks.IndexEmissionUnit ID #Stack NameStackHeight (m)StackDiameter (m)Exit Velocity(m/s)ExitTemp(oK)UTMEasting(km)UTMNorthing(km)LCCEasting(km)LCCNorthing(km)P15 TNSO2 SO2 Control Device 45.72 7.64 16.79 309.0 231.485 3963.050 1166.727 -383.375UTM 17 Coordinates correspond to a datum of NAD27; LCC coordinates are in datum NWS-84.Note: Stacks parameters from Excel Spreadsheet “Stacks_model_TNBART_December2006R1.xls” sent to Joe Scire on December 21, 2006Table 2-6. Point Source P15 Emission Rates (SO2Control Point Source forthe Wet Scrubber Scenario).SourceIDEmissionUnit ID #Stack NamePM10-PM2.5g/sSolidPM2.5g/sOrg. Condensablesg/sSO2g/sNOxg/sP15TNSO2SO2 Control Device0.0014.60.006.000.5Note: Emission rates from Excel Spreadsheet “Stacks_model_TNBART_December2006R1.xls” sent to Joe Scire on December 21, 2006Geophysical and Meteorological Data 3-1 

## 3. GEOPHYSICAL AND METEOROLOGICAL DATA

Screening runs were performed for 2001 -2003 using the VISTAS 4-km resolution CALMET Domain 3. Six Class I areas, Great Smoky Mountains National Park, Cohutta Wilderness, Joyce Kilmer/ Slickrock Wildern ess, Linville Gorge Wilderness, Shining Rock Wilderness and Mammoth Cave National Park, ar e located within the 300-km radius around the facility as it is displayed on Figure 3-1. The red outline represents the VISTAS 4-km CALMET domain, the black circle is the 300-km limit around the South Plant facility showing the Class I areas to include in the scr eening analysis, the purple outline represents the CALPUFF computation domain. The results of the screening run show that Mammoth Cave National Park does not have any exceedances of the 0.5 dv screening threshold. The highest impacts at Mammoth Cave using the VISTAS visibility procedures (Method 6, annual average natural background) were 0.17, 0.30 and 0.35 dv for 2001-2003, respectively. As a result, Mammoth Cave is not subject to further analysis. The highest impact at the other Class I areas exceeded the 0. 5 dv threshold, so these five Class I areas are included in the refined modeling analysis.

Since the South Plant facility distance to the closest receptors in the Great Smoky Mountains National Park is less than 30 km and because of the complexity of the terrain in this area, a refined run with higher grid reso lution is performed as described hereafter. The refined run includes the five remaining Class I areas while Mammoth Cave National Park is excluded.



### 3.1 Terrain

Gridded terrain elevations for the refined modeling domain are derived from 3 arc-second digital elevation models (DEMs) produced by the United States Geological Survey (USGS). Data are provided in files covering 1 degree by 1 degree blocks of latitude and longitude. The 1-degree DEMs are produced by the Defe nse Mapping Agency using cartographic and photographic sources. USGS 1:250,000 scale t opographic maps are the primary source of 1-degree DEMs.

One degree DEM data consists of an array of 1201 by 1201 elevations referenced on the geographic (latitude/longitude) coordinate system of the World Geodetic System 1972 Datum. Elevations are in meters relative to mean sea level, and the spacing of the elevations along each profile is 3 arc-s econds, which corresponds to a spacing of approximately 90 meters.

The CALMET computational domain for the refined run is a 1-km resolution domain covering part of Tennessee and North Carolina. This domain covers an area of 334 km by 259 km (Figure 3-2) which includes the five Class I areas discussed earlier and the South Plant facility with a buffer zone of 50 km on each side of the domain. The terrain is rather complex with the southern part of the Ap palachian Mountains range crossing the domain from northeast to southwest. Several valley can be described and the highest peaks can reach 2000 meters. Figure 3-2 shows contours of the terrain averaged to 1 km. The USGSGeophysical and Meteorological Data 3-2 

### elevation records located within each grid cell in the computational domain are averaged to produce a mean elevation at each grid point. Adequate representation of the important terrain features and valleys associated with the Class I area and the surrounding area are captured by the 334 x 259 grid cells, a wo rkable number of cells. The CALPUFF computational domain is the same as the CALMET domain. The CALMET and CALPUFF domain extends beyond the Class I areas in order to provide an adequate buffer zone at the boundaries, and to allow the effects of flow curvature and possible small-scale recirculation to be evaluated.



### 3.2 Land Use

The USGS land use data in the vicinity of the facility is used to produce a gridded field of dominant land use categories. The land use data used in the analysis are the Composite Theme Grid (CTG) land use data from the USGS, at a resolution of 200 m.

Land use data are processed to produce a 1 km resolution gridded field of fractional land use categories. The 37 USGS land use categories are then mapped into 14 CALMET land use categories. Surface properties such as al bedo, Bowen ratio, roughness length, and leaf area index are computed proportionally to th e fractional land use. The USGS land use categories are described in Table 3-1. Table 3-2 displays the 14 CALMET land use categories and their associated geophysical para meters. Figure 3-3 show the dominant land use categories used in the modeling.Geophysical and Meteorological Data 3-3 

### Figure 3-1. Terrain contours (m MSL) at 4 km resolution (VISTAS CALMET Domain 3) use for the screening run. The 12 Class I areas located in the domain are shown. The six Class I areas within the black circle (300-km radius around South Plant facility) are used in the screening run. The purple line delimits the CALPUFF computational domain for the screening run. 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 LCC East (km) -600 -500 -400 -300 -200 -100 0 100LCC North (km)

33.N 35.N 37.N 39.N

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m) Cohutta W Dolly Sods W

Great Smoky Mountains NP James River Face W

Joyce-Kilmer-SlickRock W Linville Gorge W South Plant Mammoth Cave NP

Mingo W Otter Creek W

Shenandoah NP

Shining Rock W

Sipsey W 

### 1

2

1 - CALMET VISTAS domain 3 2 - CALPUFF computational domain LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N 

### V ISTAS 4-km resoluti on CALMET DOMAIN 3 including all 12 Class I areas on the Domain

Class I areasGeophysical and Meteorological Data 3-4 

### Figure 3-2. Terrain contours (m MSL) at 1 km resoluti on on the 334 km x 259 km CALMET and CALPUFF model domains. The five Class I areas to be modeled in the refined run and the facility are also shown. 1100 1150 1200 1250 1300 1350 1400 LCC East (km) -500 -450 -400 -350 -300LCC North (km)

35.N 36.N .

.

. . LCC Origin: 40N, 97W

Datum: NWS-84 Matching Parallels: 33N, 45N False Easting: 0 False Northing: 0 -1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500 

### Terrain of the refined Domain with 5 Class I areas included 1km resolution domain - 334 x 259 cells

South Plant

Cohutta W Joyce Kilmer-Slickrock Shining Rock W Linville Gorge W

Great Smoky Mountains NP TN KY
NC

SC

GAGeophysical and Meteorological Data 3-5 

### Figure 3-3. Dominant land use categories at 1 km resolution on the 334 km x 259 km CALMET and CALPUFF model domains. The five Class I areas to be modeled in the refined run and the facility are also shown. 1100 1150 1200 1250 1300 1350 1400 LCC East (km) -500 -450 -400 -350 -300LCC North (km)

35.N 36.N .

.

. . LCC Origin: 40N, 97W

Datum: NWS-84 Matching Parallels: 33N, 45N 

### LandUse categories of th e refined Domain with 5 Class I areas included 1km resolution domain - 334 x 259 cells

South Plant

Cohutta W Joyce Kilmer-Slickrock Shining Rock W Linville Gorge W

Great Smoky Mountains NP Snow/Ice

Tundra

Barren

Wetland

Water

Forest

Range

Agriculture

Urban/Built-Up TN KY

NC

SC

GAGeophysical and Meteorological Data 3-6 

### 3.3 Meteorological Data Base

The wind fields in the modeling domain are e xpected to be variable. Depending on the location, some of the observational data is onl y representative of a small area around itself. The local terrain is expected to influence the local flow, much of the structure in the wind fields is determined by CALMET using its di agnostic wind field module, rather than being driven by observations.

The CALMET model requires meteorological information from the surface and upper air as well as geophysical information about the land use and terrain heights. Specifically, CALMET requires surface observations of wind speed, wind direction, temperature, cloud cover, ceiling height, surface pressure, relative humidity, and precipitation type (e.g., snow, rain, etc.). These variables are routinely me asured at the National Weather Service (NWS) surface stations. The upper air data includes tw ice-daily observations of vertical profiles of wind speed, wind direction, temperature, and pressure. In addition, hourly precipitation measurements are included in the modeling a nd are required for wet deposition calculations in CALPUFF. Three-dimensional gridded da ta from the prognostic numerical model MM5 are also included with two different resolu tion, 12-km for 2001 and 2002 and 36-km for 2003. Table 3-3 lists the types of observational and modeled data available that are used in the modeling. There are around 12-13 surface meteorological stations in the refined run that are located within the modeling domain (Tab le 3-4). The surface data is extracted from the VISTAS surface standard dataset available on the TRC Atmospheric Studies Group web site ( http://www.src.com ). Upper air data closer to the refined domain is selected from the VISTAS Domain 3 dataset (Table 3-5). The 4 u pper air stations selected are located outside the modeling refined domain.

Approximately 32-33 precipitation stations are available for use in the modeling (Table 3- 6). These data are also extracted as a subdomain of VISTAS standard precipitation dataset. Figures 3-4 to 3-6 shows the locations and spatia l coverage of all of these stations for 2001, 2002 and 2003.Geophysical and Meteorological Data 3-7 

### Table 3-1. U.S. Geological Survey Land Use and Land Cover Classification System

Level I Level II 10 Urban or Built-up Land 11 12 13 14 15 16 17 Residential Commercial and Services Industrial Transportation, Communications and Utilities Industrial and Commercial Complexes Mixed Urban or Built-up Land Other Urban or Built-up Land 20 Agricultural Land 21 22

23 24 Cropland and Pasture Orchards, Groves, Vineyards, Nurseries, and Ornamental Horticultural Areas Confined Feeding Operations Other Agricultural Land 30 Rangeland 31 32 33 Herbaceous Rangeland Shrub and Brush Rangeland Mixed Rangeland 40 Forest Land 41 42 43 Deciduous Forest Land Evergreen Forest Land Mixed Forest Land 50 Water 51 52 53 54 55 Streams and Canals Lakes Reservoirs Bays and Estuaries Oceans and Seas 60 Wetland 61 62 Forested Wetland Nonforested Wetland 70 Barren Land 71 72 73 74 75 76 77 Dry Salt Flats Beaches Sandy Areas Other than Beaches Bare Exposed Rock Strip Mines, Quarries, and Gravel Pits Transitional Areas Mixed Barren Land 80 Tundra 81 82 83 84 85 Shrub and Brush Tundra Herbaceous Tundra Bare Ground Wet Tundra Mixed Tundra 90 Perennial Snow or Ice 91 92 Perennial Snowfields GlaciersGeophysical and Meteorological Data3-8Table 3-2. Default CALMET Land Use Categories and Associated Geophysical Parameters based on the U.S. Geological Survey Land UseClassification System (14-Category System)Land Use TypeDescriptionSurfaceRoughness (m)AlbedoBowen RatioSoil HeatFlux ParameterAnthropogenicHeat Flux (W/m2)Leaf AreaIndex10 Urban or Built-up Land 1.0 0.18 1.5 .25 0.0 0.220Agricultural Land -Unirrigated0.25 0.15 1.0 .15 0.0 3.0-20*Agricultural Land - Irrigated 0.25 0.15 0.5 .15 0.0 3.030 Rangeland 0.05 0.251.0 .15 0.0 0.540 Forest Land 1.0 0.10 1.0 .15 0.0 7.050 Water 0.001 0.10 0.0 1.0 0.0 0.054 Small Water Body 0.001 0.10 0.0 1.0 0.0 0.055 Large Water Body 0.001 0.10 0.0 1.0 0.0 0.060 Wetland 1.0 0.10 0.5 .25 0.0 2.061 Forested Wetland 1.0 0.1 0.5 0.25 0.0 2.062 Nonforested Wetland 0.2 0.1 0.1 0.25 0.0 1.070 Barren Land 0.05 0.30 1.0 .15 0.0 0.0580 Tundra .20 0.30 0.5 .15 0.0 0.090 Perennial Snow or Ice.05 0.70 0.5 .15 0.0 0.0*Negative values indicate "irrigated" land useGeophysical and Meteorological Data 3-9 

### Table 3-3. Meteorological Data Sources and Parameters Available

Type of Dataset Frequency Source Parameters

Surface obs. Hourly NWS Wind speed, wind direction, temperature, ceiling height, cloud cover, relative humidity, surface pressure, precipitation type Upper Air Twice-daily NWS Soundings of wind speed, wind direction, temperature, and pressure Precipitation Hourly NWS Hourly precipitation amounts Modeled Profiles MM5 for 2001, 2002 and 2003 Hourly VISTAS/EPA Hourly, gridded fields of winds, temperature, pressure, and humidity and liquid water content on 12 km grid for 2001 and 2002. Hourly gridded fields on a 36-km grid for 2003.Geophysical and Meteorological Data 3-10 

### Table 3-4. NWS Hourly Surface Stations for 2001, 2002 and 2003

.

WMO INIT Station Name State Year Latitude Longitude Elevation (0.1 m) LCC X 1 (km) LCC Y 1 (km)

722154 KDNN Dalton GA 01,02,03 34.717 -84.867 216 1102.564 -510.885 723048 K6A3 Andrews NC 01 35.2 -83.867 518 1185.117 -445.273 723118 KCEU Clemson-Oconee Co A SC 01,02,03 34.667 -82.867 271 1283.806 -490.111 723119 KGMU Greenville Downtown SC 01,02,03 34.850 -82.350 319.4 1327.112 -462.648723120 KGSP Greer Greenv’lSpartanbrg AP SC 01,02,03 34.90 -82.217 291.7 1338.156 -455.227
723124 KGRD Greenwood AP SC 01,02,03 34.233 -82.15 192 1356.201 -527.227 723125 KAND Anderson County AP SC 01,02,03 34.5 -82.717 231.6 1300.218 -506.274 723144 KFQD Rutherfordton NC 01,02,03 35.433 -81.933 329 1353.882 -392.747 723145 KHKY Hickory Regional AP NC 01,02,03 35.733 -81.383 348.4 1397.141 -351.662 723148 KMRN Morganton/Lenior AP NC 01,02,03 35.817 -81.6 4 1376.347 -345.806 723150 KAVL Asheville Regional AP NC 01,02,03 35.433 -82.533 652.3 1300.433 -401.509 723183 KTRI Bristol TRI City AP TN 01,02,03 36.467 -82.400 457.2 1293.970 -286.574 723246 KOQT Oak Ridge TN 01,02,03 36.017 -84.233 277 1139.638 -360.373 723260 KTYS Knoxville Mcghee Tyson AP TN 01,02,03 35.817 -83.983 293.2 1164.964 -379.127

1 Lambert Conic Conformal (LCC) projec tion, LCC origin (40N, 97W), standard parallels (33N, 45N), datum NWS-84.



### Table 3-5. Upper Air Stations used for 2001, 2002 and 2003

.

# Station Name WBAN# WMO# Latitude Longitude LCC X 1 LCC Y 1 Elevation (deg) (deg) (km) (km) (m)

1 Peachtree City, GA
FFC 53819 72215 33.35 -84.56 1150.994 -657.420 246

2 Greensboro, NC
GSO 13723 72317 36.08 -79.95 1516.732 -290.880 277

3 Roanoke/Blacksburg, VA
RNK 53829 72318 37.20 -80.41 1453.770 -176.566 648

4 Nashville, TN
BNA 13897 72327 36.25 -86.57 929.093 -361.386 180

1 Lambert Conic Conformal (LCC) projection, LCC origin (4 0N, 97W), standard parallels (33N, 45N), datum NWS-84.Geophysical and Meteorological Data 3-11 

### Table 3-6. Hourly NWS Precipitati on Stations for 2001, 2002 and 2003

.

Station ID Sta te Year of Longitude Latitude LCC X 1 

### LCC Y 1 

### Data (deg) (deg) (km) (km)
91619 GA 01,02,03 34.412N 83.207W 1257.438 -522.814 91863 GA 02,03 34.759N 84.765W 1111.152 -505.028 91998 GA 01,02,03 34.450N 83.855W 1198.178 -527.400 92479 GA 01,02,03 34.572N 84.000W 1183.123 -515.908 92578 GA 01,02,03 34.417N 84.118W 1174.885 -534.457 94651 GA 01 34.456N 84.456W 1143.661 -534.485 96091 GA 01,02,03 34.929N 83.396W 1231.787 -468.722 98935 GA 01,02,03 34.721N 83.722W 1205.839 -495.903 157677 KY 01,02,03 36.667N 84.483W 1107.585 -292.208 310300 NC 01,03 35.432N 82.537W 1300.094 -401.676 310301 NC 01,02,03 35.600N 82.533W 1297.500 -383.243 310312 NC 01,02,03 35.883N 81.950W 1344.151 -343.838 310967 NC 01,02,03 36.069N 81.352W 1393.513 -314.528 314764 NC 01,02,03 35.433N 82.234W 1327.075 -397.187 317845 NC 01,02,03 35.314N 81.534W 1391.626 -399.719 318448 NC 01,02,03 35.567N 82.383W 1311.423 -384.698 380613 SC 01,02,03 34.601N 82.434W 1323.974 -491.127 381770 SC 01,02,03 34.660N 82.824W 1287.801 -490.270 383747 SC 01,02,03 34.885N 82.224W 1337.797 -456.971 384581 SC 01,02,03 34.983N 83.067W 1260.431 -458.293 385017 SC 01,02,03 34.499N 82.022W 1362.944 -496.200 385278 SC 01,02,03 34.792N 83.246W 1247.555 -481.693 386831 SC 01,02,03 34.882N 82.719W 1293.409 -464.465 388707 SC 01,02,03 34.949N 82.443W 1317.009 -453.167 388951 SC 01,02 34.398N 82.230W 1345.997 -510.354 401094 TN 01,02,03 36.473N 82.404W 1293.512 -285.975 401978 TN 01,02,03 35.029N 84.724W 1110.822 -474.866 402934 TN 01,02,03 36.142N 82.426W 1297.430 -322.459 404950 TN 01,02,03 35.818N 83.986W 1164.682 -379.056 406272 TN 01,02,03 36.169N 83.402W 1210.771 -332.974 406750 TN 01,02,03 36.023N 84.233W 1139.545 -359.715 407850 TN 01,02,03 35.766N 84.777W 1095.105 -394.595 407884 TN 01,02,03 36.416N 82.984W 1243.498 -300.302 408766 TN 01,02,03 36.249N 84.697W 1095.011 -340.636
1 Lambert Conic Conformal (LCC) projection, LCC origin (40N, 97W), standard parallels (33N, 45N), datum NWS-84.Geophysical and Meteorological Data 3-12 

### Figure 3-4 . Surface, upper air and precipitation stations and MM5 data used in the 2001 modeling. The five Class I areas and the facility are also shown. 1000 1100 1200 1300 1400 1500 LCC East (km) -600 -500 -400 -300 -200LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m)



### LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N Upper air stations Surface stations precipitation stations 

### Surface stations, Precipitation stations and Upper air station s over CALMET domain - year 2001

MM5 grid points over the domainGeophysical and Meteorological Data 3-13 

### Figure 3-5 . Surface, upper air and precipitation stations and MM5 data used in the 2002 modeling. The five Class I areas and the facility are also shown.

1000 1100 1200 1300 1400 1500 LCC East (km) -600 -500 -400 -300 -200LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m) 

### Surface stations, Precipitation stations and Upper air station s over CALMET domain - year 2002

Upper air stations Surface stations Precipitation stations LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N

MM5 grid points over the domainGeophysical and Meteorological Data 3-14 

### Figure 3-6 . Surface, upper air and precipitation stations and MM5 data used in the 2003 modeling. The five Class I areas and the facility are also shown. 1000 1100 1200 1300 1400 1500 LCC East (km) -600 -500 -400 -300 -200LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m) 

### Surface stations, Precipitation stations and Upper air station s over CALMET domain - year 2003

Upper air stations Surface stations Precipitation stations LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N

MM5 grid points over the domainGeophysical and Meteorological Data 3-15 

### 3.4 Air Quality Monitoring Data
CALPUFF uses hourly ozone concentration measur ements in the chemical transformation rates (SO 2 

### to SO 4 

### , NO x 

### to HNO 3 

### /NO 3 

### ). The ambient ozone measurements are used in determining SO 2 

### loss rates due to chemical transfor mation to sulfate and in determining NO x 

### loss rates to nitrate. Ambient ozone monitoring data for 2001, 2002 and 2003 are extracted from the U.S. EPA AIRS and CASTNet networks and are used to develop hourly ozone monitoring data files for the each year of the modeling analysis. Data for VISTAS Domain 3 are extracted from the standard ozone dataset available on the TRC CALPUFF web site ( http://www.src.com ) to create the hourly ozone file. A total of ~35 monitoring stations, listed in Table 3-7, are used in th e modeling. See Figures 3-7 to 3-9 which show the locations of each of the available stations for each year modeled.

A constant background ammonia concentr ation of 0.5 parts per billion (ppb) as recommended in the BART Modeling Protocol is used for CALPUFF runs of every point and lines sources.Geophysical and Meteorological Data 3-16 

### Table 3-7. Ozone Stations for 2001, 2002 and 2003

.

Network Year ID Latitude Longitude UTM X (km) UTM Y (km)

AIRS 01,02,03 130850001 34.37778N 84.05611W 1181.109 -537.962 AIRS 01,02,03 132130003 34.785N 84.62695W 1123.221 -500.474 AIRS 01,02,03 210130002 36.60806N 83.73695W 1174.094 -289.300 AIRS 01,02,03 370110002 35.97167N 81.93417W 1343.932 -333.920 AIRS 01,02,03 370210030 35.5N 82.6W 1293.290 -395.136 AIRS 01,02,03 370270003 35.93583N 81.53028W 1380.288 -331.779 AIRS 03 370750001 35.25793N 83.79562W 1190.583 -437.988 AIRS 01,02,03 370870004 35.50528N 82.96472W 1260.708 -399.683 AIRS 01,02,03 370870035 35.37917N 82.7925W 1278.227 -411.081 AIRS 01,02,03 370870036 35.59N 83.0775W 1249.225 -391.967 AIRS 01,02,03 370990005 35.52445N 83.23612W 1236.198 -401.313 AIRS 01,02,03 371730002 35.43551N 83.4437W 1219.158 -413.859 AIRS 01,02,03 371990003 35.73774N 82.28523W 1317.069 -364.619 AIRS 01,02,03 450010001 34.32556N 82.38611W 1333.182 -520.586 AIRS 01,02,03 450070003 34.775N 82.49028W 1315.835 -472.896 AIRS 01,02,03 450210002 35.13028N 81.81639W 1369.841 -424.079 AIRS 01,02,03 450730001 34.805N 83.2375W 1248.103 -480.151 AIRS 01,02,03 450770002 34.68607N 82.83866W 1286.031 -487.622 AIRS 01,02,03 450830009 34.98861N 82.07555W 1349.239 -443.444 AIRS 01,02,03 470010101 35.965N 84.22334W 1141.302 -365.953 AIRS 01,02,03 470090101 35.63139N 83.94361W 1171.408 -398.967 AIRS 01,02,03 470090102 35.60306N 83.78361W 1186.118 -399.997 AIRS 01,02 470630003 36.30778N 83.13448W 1232.073 -314.190 AIRS 01,02,03 470650028 35.07639N 85.15167W 1071.664 -474.795 AIRS 01,02,03 470651011 35.14028N 85.17W 1069.096 -467.990 AIRS 01,02,03 470890002 36.11445N 83.60111W 1194.058 -341.582 AIRS 01,02,03 470930021 36.08472N 83.76473W 1180.059 -346.975 AIRS 01,02,03 470931020 36.01944N 83.87361W 1171.459 -355.536 AIRS 01 470931030 35.89834N 83.95722W 1165.967 -369.882 AIRS 01,02,03 471210104 35.28889N 84.94611W 1087.033 -449.008 AIRS 01,02,03 471550101 35.69667N 83.60972W 1200.089 -387.457 AIRS 01,02,03 471550102 35.56278N 83.49806W 1212.219 -400.643 CASTNet 01,02,03 COW137 35.0608N 83.4305W 1226.514 -454.742 CASTNet 01,02,03 PNF126 36.1058N 82.0454W 1331.666 -320.908 CASTNet 01,02,03 GRS420 35.6331N 83.9422W 1171.507 -398.762 CASTNet 01,02,03 SPD111 36.47N 83.8268W 1168.403 -305.576Geophysical and Meteorological Data 3-17 

### Figure 3-7 . CASTNet and AIRS ozone stations used in the 20 01 modeling. The five Class I areas in the domain and the facility are also shown. 1100 1150 1200 1250 1300 1350 1400 LCC East (km) -500 -450 -400 -350 -300LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m)

LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N Ozone stations 

### Ozone stations location over CALMET domain - y ear 2001

South Plant TN KY NC

SC

GAGeophysical and Meteorological Data 3-18 

### Figure 3-8 . CASTNet and AIRS ozone stations used in the 2002 modeling. The five Class I areas in the domain and the facility are also shown. 1100 1150 1200 1250 1300 1350 1400 LCC East (km) -500 -450 -400 -350 -300LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m)

LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N Ozone stations 

### Ozone stations location over CALMET domain - y ear 2002

TN KY NC

SC

GA South PlantGeophysical and Meteorological Data 3-19 

### Figure 3-9 . CASTNet and AIRS ozone stations used in the 20 03 modeling. The five Class I areas in the domain and the facility are also shown. 1100 1150 1200 1250 1300 1350 1400 LCC East (km) -500 -450 -400 -350 -300LCC North (km)

-1 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m)

LCC Origin: 40.00N, 97.00W

Datum: NWS-84 Matching Parallels: 33.00N, 45.00N Ozone stations 

### Ozone stations location over CALMET domain - y ear 2003

TN KY NC

SC

GA South PlantAir Quality Modeling Methodology 4-1 

## 4. AIR QUALITY MODELING METHODOLOGY

4.1 Model Selection

The terrain of the region, the large sour ce-receptor distances, and the importance of chemical transformation, wet deposition, and dry deposition are principal factors in the selection of a modeling approach. The terra in considerations included the need to incorporate terrain channeling effects on the flow field, diurnally varying slope flows (downslope flows at night, upslope flows during the day), and representing the strong spatial variability of the wind fields over rela tively short distances. The ability to treat plume interactions and plume impingement on te rrain above stack height are also important.

The CALPUFF modeling system (Scire et al., 2000a ,b) is used in the BART analysis for the six Class I areas in the 300-km radius of Alcoa South Plant facility. CALPUFF and its meteorological model CALMET, are designed to handle the complexities posed by complex terrain, the long source receptor distances, ch emical transformation and deposition, and other issues related to Class I impacts. The CALPUFF modeling system has been adopted by the U.S. EPA as a Guideline Model for source-receptor distances greater than 50 km, and for use on a case-by-case basis in complex flow situations for shorter distances (Federal Register, April 15, 2003a). CALPUFF is recommended for Class I impact assessments by the Federal Land Managers Workgroup (FLAG, 2000) and the Interagency Workgroup on Air Quality Modeling (IWAQM, 1998). CALPUFF is recommended by the USEPA for BART analyses ( Federal Register , 6 July 2005).

CALMET is a diagnostic meteorological mode l that produces three-dimensional wind and temperature fields and two-dimensional fields of mixing heights and other meteorological fields. It contains slope flow effects, terrai n channeling, and kinematic effects of terrain. CALPUFF is a non-steady-state Gaussian puff model. It includes algorithms for building downwash effects as well as chemical transfor mation, wet deposition, and dry deposition. One capability of CALPUFF not found in many specialized models such as CTDMPLUS is the ability to treat the combined effects of multiple processes (e.g., building downwash effects in complex terrain; dry deposition and overwater dispersion, etc.). A complete summary of the capabilities and features of CALMET and CALPUFF is provided in Sections 4.1.1 and 4.1.2.

Regulatory models such as the Industrial Source Complex Short Term (ISCST3) model have several important limitations for this study. One critical limitation is that ISCST3 is a steady-state, straight line plume model that cannot respond to the significant terrain-induced spatial variability to the wind fields that domin ate transport in the vicinity of the Class I areas. ISCST3 uses spatially-invariant wind fields based on single-station wind observations. Also, the steady-state formul ation does not account for causality effects, which can be important for source-receptor distances greater than a few kilometers.Air Quality Modeling Methodology 4-2 

### 4.1.1 Major Features of CALMET
The CALMET meteorological model consists of a diagnostic wind field module and micrometeorological modules for overwater and overland boundary layers. When using large domains, the user has the option to ad just input winds to a Lambert Conformal Projection coordinate system to account for Earth's curvature. The diagnostic wind field module uses a two-step approach to the computation of the wind fields (Douglas and Kessler, 1988). In the first step, an initial-gu ess wind field is adjusted for kinematic effects of terrain, slope flows, and terrain blocking effects to produce a Step 1 wind field. The second step consists of an objective analysis pr ocedure to introduce observational data into the Step 1 wind field to produce a final wind field.

The major features and options of the meteorological model are summarized in Table 4-1. The techniques used in the CALMET m odel are briefly described below.

Step 1 Wind Field

Kinematic Effects of Terrain : The approach of Liu and Yock e (1980) is used to evaluate kinematic terrain effects. The domain-scale winds are used to compute a terrain-forced vertical velocity, subject to an exponentia l, stability-dependent decay function. The kinematic effects of terrain on the horizontal wind components are evaluated by applying a divergence-minimization scheme to the in itial guess wind field. The divergence minimization scheme is applied iteratively until the three-dimensional divergence is less than a threshold value.

Slope Flows : The slope flow algorithm in CALMET has recently been upgraded (Scire and Robe, 1997). It is based on the shooting flow algorithm of Mahrt (1982). This scheme includes both advective-gravity and equilibrium flow regimes. At night, the slope flow model parameterizes the flow down the sides of the valley walls into the floor of the valley, and during the day, upslope flows are parameterized. The magnitude of the slope flow depends on the local surface sensible heat flux an d local terrain gradients. The slope flow wind components are added to the wind fi eld adjusted for kinematic effects.

Blocking Effects : The thermodynamic blocking effects of terrain on the wind flow are parameterized in terms of the local Froude number (Allwine and Whiteman, 1985). If the Froude number at a particular grid point is less than a critical value and the wind has an uphill component, the wind direction is adjusted to be tangent to the terrain.Air Quality Modeling Methodology 4-3 

### Table 4-1. Major Features of the CALMET Meteorological Model

Boundary Layer Modules of CALMET

- Overland Boundary Layer - Energy Balance Method - Overwater Boundary Layer - Profile Method - Produces Gridded Fields of: - Surface Friction Velocity - Convective Velocity Scale - Monin-Obukhov Length - Mixing Height - PGT Stability Class - Air Temperature (3-D) - Precipitation Rate

• Diagnostic Wind Field Module of CALMET - Slope Flows - Kinematic Terrain Effects - Terrain Blocking Effects - Divergence Minimization - Produces Gridded Fields of U, V, W Wind Components - Inputs Include Domain-S cale Winds, Observations, and

(optionally) Coarse-Grid Prognostic Model Winds - Lambert Conformal Projection CapabilityAir Quality Modeling Methodology 4-4 

### Step 2 Wind Field

The wind field resulting from the adjustments described above of the initial-guess wind is the Step 1 wind field. The second step of the procedure involves the introduction of observational data into the Step 1 wind field through an objective analysis procedure. An inverse-distance squared interpolation scheme is used which weighs observational data heavily in the vicinity of the observational station, while the Step 1 wind field dominates the interpolated wind field in regions with no observational data. The resulting wind field is subject to smoothing, an optional adjustment of vertical velocities based on the O'Brien (1970) method, and divergence minimization to produce a final Step 2 wind field.

CALMET Boundary Layer Models

The CALMET model contains two boundary laye r models for application to overland and overwater grid cells.

Overland Boundary Layer Model : Over land surfaces, the energy balance method of Holtslag and van Ulden (1983) is used to comput e hourly gridded fields of the sensible heat flux, surface friction velocity, Monin-Obukhov length, and convective velocity scale. Mixing heights are determined from the comput ed hourly surface heat fluxes and observed temperature soundings using a modified Ca rson (1973) method based on Maul (1980). Gridded fields of Pasquill-Gifford-Turner ( 

### PGT) stability class and optional hourly precipitation rates are also determined by the model.

Overwater Boundary Layer Model : The aerodynamic and thermal properties of water surfaces suggest that a different method is best suited for calculating the boundary layer parameters in the marine environment. A profile technique, using air-sea temperature differences, is used in CALMET to compute the micrometeorological parameters in the marine boundary layer.

An upwind-looking spatial averaging scheme is optionally applied to the mixing heights and 3-dimensional temperature fields in orde r to account for important advective effects.
4.1.2 Major Features of CALPUFF
By its puff-based formulation and through the use of three-dimensional meteorological data developed by the CALMET meteorological mode l, CALPUFF can simulate the effects of time- and space-varying meteorological conditio ns on pollutant transport from sources in complex terrain. The major features and options of the CALPUFF model are summarized in Table 4-2. Some of the technical algorithms are briefly described below.

Complex Terrain: The effects of complex terrain on puff transport are derived from the CALMET winds. In addition, puff-terrain inte ractions at gridded and discrete receptor locations are simulated using one of two algorithms that modify the puff-height (either that of ISCST3 or a general "plume path coefficien t" adjustment), or an algorithm that simulates enhanced vertical dispersion derived from the weakly-stratified flow and dispersion moduleAir Quality Modeling Methodology 4-5

### of the Complex Terrain Dispersion Model (CTDMPLUS) (Perry et al., 1989). The puffheight adjustment algorithms rely on the recepto r elevation (relative to the elevation at the source) and the height of the puff above the surface. The enhanced dispersion adjustment relies on the slope of the gridded terrain in th e direction of transport during the time step.

Subgrid Scale Complex Terrain (CTSG): An optional module in CALPUFF, CTSG treats terrain features that are not resolved by the gridded terrain field, and is based on the Complex Terrain Dispersion Model (CTDMPLUS) (Perry et al., 1989). Plume impingement on subgrid-scale hills is evaluated at the CTSG subgroup of receptors using a dividing streamline height (H d 

### ) to determine which pollutant material is deflected around the sides of a hill (below H d 

### ) and which material is advected over the hill (above H d 

### ). The local flow (near the feature) used to define H d 

### is taken from the gridded CALMET fields. As in CTDMPLUS, each feature is modeled in isolation with its own set of receptors.

Puff Sampling Functions: A set of accurate and computationally efficient puff sampling routines are included in CALPUFF which solv e many of the computational difficulties encountered when applying a puff model to nea r-field releases. For near-field applications during rapidly-varying meteorological cond itions, an elongated puff (slug) sampling function may be used. An integrated puff approach may be used during less demanding conditions. Both techniques reproduce contin uous plume results under the appropriate steady state conditions.

Building Downwash: The Huber-Snyder and Schulman-Scire downwash models are both incorporated into CALPUFF. An option is provi ded to use either model for all stacks, or make the choice on a stack-by-stack and wind sector-by-wind sector basis. Both algorithms have been implemented in such a way as to a llow the use of wind direction specific building dimensions. CALPUFF also includes the PRIME building downwash module.

Dispersion Coefficients: Several options are provided in CALPUFF for the computation of dispersion coefficients, including the use of turbulence measurements ( σ v 

### and σ w 

### ), the use of similarity theory to estimate σ v 

### and σ w 

### from modeled surface heat and momentum fluxes, or the use of Pasquill-Gifford (PG) or McElroy-Pooler (MP) dispersion coefficients, or dispersion equations based on the Complex Terrain Dispersion Model (CTDM). Options are provided to apply an averaging time correction or surface roughness length adjustments to the PG coefficients.

Overwater and Coastal Interaction Effects: Because the CALMET meteorological model contains both overwater and overland boundary layer algorithms, the effects of water bodies on plume transport, dispersion, and de position can be simulated with CALPUFF. The puff formulation of CALPUFF is designed to handle spatial changes in meteorological and dispersion conditions, including the abrupt changes that occur at the coastline of a major body of water.

Dry Deposition: A full resistance model is provided in CALPUFF for the computation of dry deposition rates of gases and particulate ma tter as a function of geophysical parameters, meteorological conditions, and pollutant speci es. Options are provided to allow userAir Quality Modeling Methodology 4-6 

### specified, diurnally varying de position velocities to be used for one or more pollutants instead of the resistance model (e.g., for sens itivity testing) or to by-pass the dry deposition model completely. For particles, source-speci fic mass distributions may be provided for use in the resistance model.

Wind Shear Effects: CALPUFF contains an optional puff splitting algorithm that allows vertical wind shear effects across individual pu ffs to be simulated. Differential rates of dispersion and transport among the "new" puffs generated from the original, well-mixed puff can substantially increase the effective ra te of horizontal spread of the material.

Wet Deposition: An empirical scavenging coefficient approach is used in CALPUFF to compute the depletion and wet deposition fl uxes due to precipitation scavenging. The scavenging coefficients are specified as a func tion of the pollutant and precipitation type (i.e., frozen vs. liquid precipitation).

Chemical Transformation: CALPUFF includes options for parameterizing chemical transformation effects using the five species scheme (SO 2 

### , SO = 4 

### , NO x 

### , HNO 3 

### , and NO − 3 

### ) employed in the MESOPUFF II model or a set of user-specified, diurnally-varying transformation rates.Air Quality Modeling Methodology 4-7 

### Table 4-2. Major Features of the CALPUFF Model

.

• Source types - Point sources (constant or variable emissions) - Line sources (constant or variable emissions) - Volume sources (constant or variable emissions) - Area sources (constant or variable emissions)

• Non-steady-state emissions and meteorological conditions - Gridded 3-D fields of meteorological variables (winds, temperature) - Spatially-variable fields of mixing height, friction velocity, convective velocity scale, Monin-Obukhov length, precipitation rate - Vertically and horizontally-var ying turbulence and dispersion rates - Time-dependent source and emissions data for point, area, and volume sources - Temporal or wind-dependent scaling fa ctors for emission rates, for all source types

• Interface to the Emissions Production Model (EPM) - Time-varying heat flux and emi ssions from controlled burns and wildfires

• Efficient sampling functions - Integrated puff formulation - Elongated puff (slug) formulation

• Dispersion coefficient ( σ y , σ z ) options - Direct measurements of σ v and σ w - Estimated values of σ v and σ w based on similarity theory - Pasquill-Gifford (PG) dispersion coefficients (rural areas) - McElroy-Pooler (MP) disper sion coefficients (urban areas) - CTDM dispersion coefficients (neutral/stable)

• Vertical wind shear - Puff splitting - Differential advection and dispersion

• Plume rise - Buoyant and momentum rise - Stack tip effects - Building downwash effects - Partial penetration - Vertical wind shear

• Building downwash - Huber-Snyder method - Schulman-Scire method - PRIME method

• Complex terrain - Steering effects in CALMET wind field - Optional puff height adjustment: ISC3 or "plume path coefficient" - Optional enhanced vertical dispersion (neutral/weakly stable flow in CTDMPLUS)Air Quality Modeling Methodology 4-8 

### Table 4-2. Major Features of the CALPUFF Model (Cont’d)

• Subgrid scale complex terrain (CTSG option) - Dividing streamline, H d , as in CTDMPLUS: - Above H d , material flows over the hill and experiences altered diffusion rates - Below H d , material deflects around the hill, splits, and wraps around the hill

• Dry Deposition - Gases and particulate matter - Three options: - Full treatment of space and time vari ations of deposition with a resistance model - User-specified diur nal cycles for each pollutant - No dry deposition

• Overwater and coastal interaction effects - Overwater boundary layer parameters - Abrupt change in meteorological conditions, plume dispersion at coastal boundary - Plume fumigation

• Chemical transformation options - Pseudo-first-order ch emical mechanism for SO 2 , SO = 4 , NO x , HNO 3 , and NO − 3 (MESOPUFF II method) - Pseudo-first-order chemical mechanism for SO 2 , SO = 4 , NO, NO 2 HNO 3 , and NO − 3 (RIVAD/ARM3 method) - User-specified diurnal cycles of transformation rates - No chemical conversion

• Wet Removal - Scavenging coefficient approach - Removal rate a function of precipitation intensity and precipitation type

• Graphical User Interface - Point-and-click model setup and data input - Enhanced error checking of model inputs - On-line Help files

• Interface Utilities - Scan ISCST3 and AUSPLUME meteorological data files for problems - Translate ISCST3 and AUSPLUME input files to CALPUFF input formatAir Quality Modeling Methodology 4-9 

### 4.2 Modeling Domain

CALMET and CALPUFF use terrain-following coordi nates. In order to cover a large enough area for the refined analysis, a modeling domain of 334 x 259 grid cells, uniform in the horizontal with a spatial resolution of 1km is used. In the vertical, a stretched grid is used with finer resolution in the lower layers and somewhat coarser resolution aloft thus allowing adequate representation of the mixed laye r. The ten vertical levels are centered at: 10, 30, 60, 120, 240, 480, 920, 1600, 2500 and 3500 meters.

CALPUFF is run for three years, 2001, 2002 and 2003. A network of discrete receptors derived from the list of receptors developed by the National Park Service (NPS) are located within the boundaries of the five Class I areas, Great Smoky Mountains National Park, Linville Gorge, Shining Rock, Cohutta and Joyce-Kilmer/ Slickrock Wilderness Areas.


### 4.3 Meteorological Modeling Options

Initial Guess Field

MM5 data are used to define the initial guess field for the CALMET simulations. For 2001 and 2002 hourly MM5 data with an interval of 12 km and 34 vertical levels are used as the initial guess wind field. MM5 data with an interv al of 36 km and 34 vertical levels are used as the initial guess wind field for 2003.

Step 1 Field: Terrain Effects

In developing the Step 1 wind field, CALMET adjusts the initial guess field to reflect kinematic effects of the terrain, slope flows a nd blocking effects. Sl ope flows are a function of the local slope and altitude of the nearest crest. The crest is defined as the highest peak within a radius TERRAD around each grid point. A value of TERRAD of 15 km is determined based on an analysis of the scale of the terrain and is used in the CALMET simulations. The Step 1 field produces a flow field consistent with the fine-scale CALMET terrain resolution (1 km).

Step 2 Field: Objective Analysis

In Step 2, observations are incorporated into the Step 1 wind field to produce a final wind field. Each observation site influences the fi nal wind field within a radius of influence (parameters RMAX1 at the surface and RMAX2 aloft). Observations and Step 1 field are weighted by means of parameters R1 at the surface and R2 aloft: at a distance R1 from an observation site, the Step 1 wind field and th e surface observations are weighted equally. RMAX1 and RMAX2 are set to large values (40 km), while small values of R1 and R2 (5km) are used in order to limit the influence of observations on the grid so that important terrain effects are not smoothed out.


### 4.4 Dispersion Modeling Options

The CALPUFF simulations is conducted using the following model options:Air Quality Modeling Methodology 4-10 

### - Gaussian near-field distribution - Transitional plume rise - Stack tip downwash - Pasquill-Gifford (PG) dispersion coefficients (rural areas), McElroy-Pooler

coefficients (urban areas) - Transition of σ y 

### to time-dependent (Heffter) growth rates - Partial plume path adjustment for terrain - Wet deposition, dry deposition, and ch emical transformation are considered

The CALPUFF computational grid is the same as the meteorological grid. The modeling domain includes a buffer zone of at least 50 km around the source area and beyond the borders of the Class I areas. This eliminates e dge effects and allows pollutants involved in flow reversals to be brought back into the Class I area.

Two important computational parameters in CALPUFF are XMXLEN (maximum length of an emitted puff, in grid units) and XSAMLEN (maximum travel distance of a puff, in grid units, during one time step). Both of these variables are set to 1.0 in the CALPUFF simulations in order to allow the strong wind channeling effects to be accounted for in the puff trajectory calculations. The first parameter ensures that the length of an emitted puff does not become so large so that it cannot r espond to changes in the wind field on the scale of the meteorological grid. The model automatically increases the frequency of puff releases to ensure the length of a single puff is not larger than the grid size. The second parameter decreases the internal time step to ensure the travel distance during one time step does not exceed the grid size.

The partial plume path adjustment option is used in CALPUFF for this analysis (MCTADJ=3). The CALMET wind field incorporat es the effect of the terrain on the plume trajectories. The plume path coefficient is used to characterize the local effect on groundlevel concentrations. The default plume path co efficients (PPC) used for this analysis are listed below:

Stability Class A B C D E F PPC 0.5 0.5 0.5 0.5 0.35 0.35

Deposition and chemical transformation eff ects are modeled using the default dry deposition model, the scavenging coefficient wet removal module, and the default chemical transformation mechanism. A total of elev en species are modeled with CALPUFF for this analysis: SO 2 

### , SO 4 

### , NO x 

### , HNO 3 

### , NO 3, 

### and six subcategories of PM 10 

### , (PM 800 

### , PM 425 

### , PM 187 

### , PM 112 

### , PM 081 

### , PM 056 

### ). Of these eleven species, thr ee are emitted by the Alcoa sources: SO 2 

### , NO x 

### , PM 10 

### , with PM 10 

### being divided into the six subcategories described above. The chemical mechanism computes transformation rates of SO 2 

### to SO 4 

### and NO x 

### to NO 3 

### /HNO 3 

### . Hourly measured ozone concentrations are pr ovided in an external OZONE.DAT file for use with the chemical transformation module. These ozone concentrations, along with radiation intensity, are used as surrogates for the OH concentration during the day when the gas phase free radical chemistry is active.Air Quality Modeling Methodology 4-11 

### To allow for flexibility each source is modele d by group of same emission rates and their source contributions are summed at the end.


### 4.5 Visibility Calculations

Calculations of the impact of the simu lated plume particulate matter component concentrations on light extinction is carri ed out in the CALPOST postprocessor. The procedures is consistent with the VISTAS m odeling protocol (VISTAS, 2005). In this analysis, both the original IMPROVE/EPA equation and the new IMPROVE equation are applied to determine the change in light extinction due to changes in component concentrations. Using the notations of CALPO ST, the original formula is the following:

B ext 

### = 3f(RH)[(NH 4 

### )2SO 4 

### ] + 3f(RH)[NH 4 

### NO 3 

### ] + 4[OC] + 1[Soil] + 0.6[Coarse Mass] +10[EC] + b ray 

### The concentrations, in square brackets, are in μ g/m 3 

### and b ext 

### is in units of Mm -1 

### . The Rayleigh scattering term (b ray 

### ) has a default value of 10 Mm -1 

### , as recommended in EPA guidelines for tracking reasonable progress (EPA, 2003a). Note that organic carbon (OC) consists of condensable particulates which are assumed to be split evenly between the lowest two particle size categories. Soil is fine particulates which is defined as PM 2.5 

### . These species are created through scaling and summing of the various CALPUFF output files using the POSTUTIL program.

There are a few important differences in detail and in notation between the CALPOST formula for estimating light extinction and that of IMPROVE and EPA. First, the OC in the formula above represents organic carbonaceous matter (OMC in IMPROVE’s notation), which is 1.4 times the OC (i.e. organic carbon alone) in the IMPROVE formula. The EC above in synonymous with LAC in the IMPROVE formula. New implementations were added in CALPOST regarding the choice of f(RH) curve. One can now choose from IMPROVE f(RH) curve, whose values are doc umented in the December 2000 FLAG report, EPA f(RH) curve, as documented in EPA’s regional haze guidance documents, 2003 and IWAQM 1998 f(RH) curve. Also, CALPOST set s the maximum relative humidity at 98 percent by default (although the user can change it), while the EPA guidance now caps it at 95 percent.

The haze index (HI) is calculated from the extinc tion coefficient via the following formula:

HI = 10 ln(b ext /10)



### Where HI is in units of deciviews (dv) and bext is in Mm -1 

### . The impact of a source is determined by comparing HI for estimated na tural background conditions with the impact of the source and without the impact of the source

. 

### CALPOST Method 6 is used to compute the extinc tion change in deciviews consistent with the procedures outlined in the VISTAS modeling protocol.Air Quality Modeling Methodology 4-12 

### A monthly background concentration must be en tered into the CALPOST input control file. This background concentration is entered only for SOIL. The way it is computed makes it suitable to represent background light extincti on for all particulates (hygroscopic + nonhygroscopic) at the same time when multip lied by an extinction coefficient of 1.

From the natural background light extinction shown in Table 4-3, taken from Appendix B of the Guidance for Estimating Natural Visib ility Conditions Under the Regional Haze Program (September 2003) and based on the annual average natural background for example in Great Smoky Mountains National park , the value of the Haze Index (HI) for the annual average is equal to 7.60 dv. It can be converted to the total background light extinction b back 

### for the annual average using the following equation:

10 

### 10 HI

back 

### e b

⋅ =
Where HI is Haze Index expressed in units of deciviews (dv).

Therefore, total b back 

### for the annual average in Great Smoky Mountains NP, including the Rayleigh scattering coefficient is calculated as

1 10 60

. 7 

### 38

. 21 10 − 

### = ⋅ = Mm e b back

soil soil ray back 

### b b b b + = + = 10
,
Where 1 

### 10 − 

### = Mm b ray 

### and soil 

### b represents the extinction for all particulates in the background (hygroscopic or non-hygroscopic).

Hence,

1 

### 38

. 11 − 

### = Mm b soil



### And since the extinction coefficient for soil soil 

### C is 1.0, the monthly background concentration for soil (BKSOIL) to be put in CALPOST is 11.38 μ g/m 3 

### for every month. Indeed,



### BKSOIL C b soil

soil 

### ⋅ =

Table 4-3 provides the background soil valu es used in the CALPOST processing for the 5 Class I areas within the 300 km circle around th e facility to be analyzed while Table 4-4 provides the monthly f(rh) values based on the centroid of the Class I area as required for application of Method 6. The monthly f(RH) values for each month are extracted from Appendix A of Guidance for Estimating Natural Visi bility Conditions Under the Regional Haze Program (September 2003)

.Air Quality Modeling Methodology 4-13 

### While, the highest predicted light extinction change value expressed in deciviews was compared to the threshold value of 0. 5 deciviews for the screening run, the 8 th 

### highest (98 th 

### percentile) predicted light extinction change is now compared to the threshold value of 0.5 deciview for the refined run.

CALPOST Method 8 is also used to compute the extinction change in deciviews. This method is an implementation of the new IMPROVE algorithm. It provides a better correspondence between the measured visib ility and that calculated from pollutant concentrations simulated by a model. A descr iption of this method is provided in Appendix A. For CALPOST Method 8 option, the ratio NO 2 

### /NO x 

### is set to 1.0. The extinction due to Rayleigh scattering is set to 11Mm -1 

### for all the Class I areas, except Shining Rock, where it is set to 10 Mm -1 

### . The sea salt background concentration for all year is set to 0.03 μ g/m 3 

### for Cohutta W, Shining Rock W and Joyce-Kilmer/ Slickrock W and to 0.02 μ g/m 3 

### at Great Smoky Mountains NP and Linville Gorge W. Th e all year background concentration is set for every Class I area to 0.23 μ g/m 3 

### for SO 4 

### , 0.1 μ g/m 3 

### for NO 3 

### , 3.0 μ g/m 3 

### for PMC, 1.8
μ g/m 3 

### for OC, 0.5 μ g/m 3 

### for SOIL and 0.02 μ g/m 3 

### for EC according to the document “A postprocessor for Recalculating CALPOST Visi bility Outputs with the New IMPROVE Algorithm”, October 14, 2006 by Ivar Tombach.Air Quality Modeling Methodology 4-14 

### Table 4-3. Summary of Natural Background.

Class I area Annual b ext 

### (Mm -1 

### ) Annual HI (dv) Bsoil (Mm -1 

### ) Great Smoky Mountains NP 21.38 7.60 11.38

Linville Gorge W 21.36 7.59 11.36
Shining Rock W 21.40 7.61 11.40
Joyce-Kilmer/ SlickRock W 21.40 7.61 11.40

Cohutta W 21.38 7.60 11.38

Source: Guidance for Estimating Natural Visi bility Conditions Under th e Regional Haze Program (S eptember 2003), Appendix B.



### Table 4-4. Monthly Site-Specific f(RH) Values Based on the Centroid of the Area, for Visibility Methods 6 and 8 Application s.

Class I area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Great Smoky Mountains NP 3.3 3.0 

### 2.9 2.7 3.2 3.9 3.8 4.0 4.2 3.8 3.3 3.4

Linville Gorge W 3.3 3.0 

### 3.0 2.7 3.3 3.9 4.1 4.5 4.4 3.7 3.2 3.4 Shining Rock W 3.3 3.0 

### 2.9 2.7 3.4 3.9 4.1 4.5 4.4 3.8 3.3 3.4 Joyce Kilmer/ SlickRock W 3.3 3.1 

### 2.9 2.7 3.3 3.8 4.0 4.2 4.2 3.8 3.3 3.5

Cohutta W 3.3 3.1 

### 3.0 2.8 3.4 3.8 4.0 4.2 4.2 3.8 3.4 3.5

Source: Guidance for Estimating Natural Visibilit y Conditions Under the Regional Haze Program (September 2003), Appendix A,
Table A-3.Air Quality Modeling Methodology 5-1 

## 5. RESULTS

The results of the initial base case visibility impact analysis using CALPOST Method 6 for Alcoa South Plant in Tennessee are summarized in the three following tables, Table 5-1 for year 2001, Table 5-2 for year 2002 and Table 5-3 for year 2003. Since this is a refined analysis run, the 8 th 

### highest (98 th 

### percentile) simulated light extinction changes are compared to the threshold value of 0.5 deciview for all five Class I areas.

For Linville Gorge and Shining Rock Wild erness Areas when using CALPOST Method 6, the highest, second or third highest change in light extinction is below the 0.5 deciview threshold. For Cohutta wilderness, the 5 th 

### highest change in light extinction in 2001 and 2002 and the 7 th 

### highest change in light extinction in 2003 are below the 0.5 deciview threshold. The three Class I areas are also be low the visibility significance threshold of 0.5 dv change at the 98 th 

### percentile level when CALPOST Met hod 8 is applied (Tables 5-4 to 5- 6). So, these three Class I areas (Linville Go rge, Shining Rock and Cohutta Wilderness Areas) meet the standard threshold for th e initial base case run and no further analysis implying BART control scenarios need to be applied at these three Class I areas.

However, Great Smoky Mountains National Pa rk and Joyce-Kilmer/ Slickrock wilderness area exceed the 0.5 dv change threshold for a ll three years. Joyce-Kilmer/ Slickrock is below the threshold for 2001 when CALPOST Method 8 is applied (Tables 5-4 to 5-6). For these two Class I areas, a BART control scenario analysis is required. An evaluation of the effect of BART controls at the facility is analyzed for these two Class I areas.

An additional scenario is presented to estimate the effect of SO 2 

### controls on the change in visibility impact due to this facility. This scen ario, described in Section 2.2, is using wet scrubbers. The CALPOST Method 6 results for this scenario are summarized in Tables 5-7 to 5-9 for years 2001, 2002, 2003 respectively. Joyce-Kilmer/ Slickrock Wilderness impacts with controls are below the 0.5 dv change threshold for all three years. Impacts at the Great Smoky Mountain National Park ex ceed the threshold when CALPOST Method 6 is applied. The results using the more refined CALPOST Method 8 for the wet scrubber scenario and for all three years are summarize d in Tables 5-10 to 5-12. Impacts at the Joyce-Kilmer/ Slickrock Wilderness Area are below the 0.5 dv change threshold for all three years. The impacts at the Great Sm oky Mountain National Park is below the threshold for 2002 but above for 2001 and 2003.

Tables 5-13 and 5-14 summarizes the complianc e for the base case scenario and for the wet scrubber scenario respectively. Table 5-15 gives the source contribution for the initial run at the 98 th 

### percentile light extinction change using CALPOST Method 6.

In conclusion, the impacts at three Class I areas, Linville Gorge Wilderness, Shining Rock Wilderness and Cohutta Wilderness are below the significant threshold for the base case runs and did not require any more control modeling. The impacts at the Joyce-Kilmer/ Slickrock Wilderness are below the 0.5 threshold for the wet scrubber control scenario for all three years with both CALPOST Method 6 and Method 8. The impacts at the GreatAir Quality Modeling Methodology 5-2 

### Smoky Mountains National Park are below the 0.5 dv threshold 2002 for the wet scrubber control scenario with the use of CALPOST Met hod 8, but above the threshold for 2001 and 2003.Air Quality Modeling Methodology 5-3 

### Table 5-1. Results for Visibility Impact using Method 6 – Base Case Run - Year 2001

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 2.227
2.121
1.687
1.525
1.424
1.356
1.342
1.273 1175.701; -398.594 1176.920; -396.551 1175.435; -396.767 1179.623; -394.292 1175.435; -396.767 1181.107; -394.076 1170.121; -412.460 1178.139; -394.509 365 0h
360 0h
231 0h
221 0h
192 0h
226 0h
224 0h
33 0h 58 13

Linville Gorge 0.385 1345.583; -336.544 189 0h 0 0 Shining Rock 0.462 1272.465; -405.445 257 0h 0 0

Joyce-Kilmer/ SlickRock 1.503
1.109
0.755
0.740
0.711
0.589
0.588
0.511 1167.847; -423.047 1167.935; -418.371 1169.555; -419.071 1172.400; -417.727 1170.167; -418.050 1167.935; -418.371 1167.935; -418.371 1172.400; -417.727 224 0h
172 0h
20 0h
221 0h
13 0h
204 0h
130 0h
260 0h 8 2

Cohutta 0.809
0.656
0.533
0.509 0.499 1132.719; -476.504 1119.974; -478.260 1128.844; -476.107 1119.974, -478.260 1125.861, -493.304 224 0h
346 0h
161 0h
11 0h 261 0h 4 0Air Quality Modeling Methodology 5-4 

### Table 5-2. Results for Visibility Impact using Method 6 –Base Case Run - Year 2002

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.959
1.933
1.520
1.518
1.403
1.232
1.224
1.189 1175.435; -396.767 1192.709; -390.508 1192.709; -390.508 1181.107, -394.076 1178.139; -394.509 1178.404; -396.335 1198.372; -387.805 1178.139; -394.509 199 0h
285 0h
247 0h
295 0h
196 0h
336 0h
197 0h
238 0h 47 15

Linville Gorge 0.446 1347.717; -349.286 236 0h 0 0

Shining Rock 0.567
0.530 0.497 1265.287; -413.110 1272.465; -405.445 1276.416, -416.040 197 0h
301.0h 260 0h 2 0

Joyce-Kilmer/ Slickrock 1.140
0.982
0.940
0.799
0.723
0.701
0.694
0.677 1167.935; -418.371 1167.979; -423.961 1167.935; -418.371 1167.935; -418.371 1167.935; -418.371 1167.935; -418.371 1170.912; -417.942 1167.935; -418.371 297 0h
198 0h
321 0h
298 0h
197 0h
248 0h
54 0h
183 h0 17 1

Cohutta 0.720
0.703
0.633
0.632 0.413 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 296 0h
301 0h
184 0h
239 0h 241 0h 4 0Air Quality Modeling Methodology 5-5 

### Table 5-3. Results for Visibility Impact using Method 6 – Base Case Run - Year 2003

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 3.011
2.420
2.174
1.997
1.972
1.946
1.928
1.620 1175.435; -396.767 1178.139; -394.509 1175.435; -396.767 1178.139; -394.509 1169.066; -405.151 1178.139; -394.509 1171.774; -402.894 1179.623; -394.292 224 0h
238 0h
291 0h
264 0h
223 0h
12 0h
179 0h
76 0h 63 24

Linville Gorge 0.747 0.475 1347.717; -349.286 1345.583; -336.544 60 0h 182 0h 1 0

Shining Rock 0.359 1276.416; -416.040 201 0h 0 0

Joyce-Kilmer/ Slickrock 1.457
1.310
1.257
1.248
1.140
0.979
0.932
0.837 1167.935; -418.371 1167.935; -418.371 1170.912; -417.942 1172.400; -417.727 1172.400; -417.727 1167.935; -418.371 1172.400; -417.727 1170.167; -418.050 223 0h
291 0h
239 0h
224 0h
179 0h
185 0h
238 0h
236 0h 23 5

Cohutta 0.784
0.709
0.616
0.509
0.507
0.504 0.492 1127.219; -475.399 1132.719; -476.504 1119.974; -478.260 1131.482; -484.136 1132.719, -476.504 1126.469, -475.503 1119.974, -478.260 253 0h
239 0h
254 0h
221 0h
199 0h
231 0h 206 0h 6 0Air Quality Modeling Methodology 5-6 

### Table 5-4. Results for visibility impact using Method 8 –Base Case run - year 2001

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.956
1.745
1.384
1.244
1.157
1.123
1.106
1.092 1175.701; -398.594 1176.920; -396.551 1175.435; -396.767 1179.623; -394.292 1175.435; -396.767 1178.139; -394.509 1181.107; -394.076 1170.121; -412.460 365 0h
360 0h
231 0h
221 0h
192 0h
33 0h
226 0h
224 0h 38 8

Linville Gorge 0.301 1345.583; -336.544 189 0h 0 0 Shining Rock 0.375 1272.465; -405.445 257 0h 0 0

Joyce-Kilmer/ SlickRock 1.242
0.896
0.605
0.593
0.554 0.474 1167.847; -423.047 1167.935; -418.371 1172.400; -417.727 1169.555; -419.071 1170.167; -418.050 1167.935, -418.371 224 0h
172 0h
221 0h
20 0h
13 0h 204 0h 5 1

Cohutta 0.660
0.518 0.427 1132.719; -476.504 1119.974; -478.260 1128.844, -476.107 224 0h
346 0h 161 0h 2 0Air Quality Modeling Methodology 5-7 

### Table 5-5. Results for visibility impact using Method 8 –Base Case run - year 2002

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.604
1.578
1.256
1.240
1.138
1.092
0.990
0.966 1175.435; -396.767 1192.709; -390.508 1192.709; -390.508 1181.107, -394.076 1178.139; -394.509 1178.404; -396.335 1198.372; -387.805 1178.139; -394.509 199 0h
285 0h
247 0h
295 0h
196 0h
336 0h
197 0h
238 0h 40 6

Linville Gorge 0.363 1347.717; -349.286 236 0h 0 0 Shining Rock 0.463 1265.287; -413.110 197 0h 0 0

Joyce-Kilmer/ SlickRock 0.921
0.796
0.754
0.643
0.584
0.573
0.567
0.549 1167.935; -418.371 1167.979; -423.961 1167.935; -418.371 1167.935; -418.371 1167.935; -418.371 1167.935; -418.371 1170.912; -417.942 1167.935; -418.371 297 0h
198 0h
321 0h
298 0h
197 0h
248 0h
54 0h
245 0h 10 0

Cohutta 0.577
0.564
0.514
0.508 0.335 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 1119.974; -478.260 296 0h
301 0h
239 0h
184 0h 241 0h 4 0Air Quality Modeling Methodology 5-8 

### Table 5-6. Results for visibility impact using Method 8 – Base Case run - year 2003

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 2.508
1.998
1.782
1.706
1.659
1.622
1.550
1.310 1175.435; -396.767 1178.139; -394.509 1175.435; -396.767 1178.139; -394.509 1178.139; -394.509 1169.066; -405.151 1171.774; -402.894 1181.107; -394.076 224 0h
238 0h
291 0h
12 0h
264 0h
223 0h
179 0h
251 0h 49 20

Linville Gorge 0.575 0.370 1347.717; -349.286 1345.583; -336.544 60 0h 182 0h 1 0

Shining Rock 0.293 1276.416; -416.040 201 0h 0 0

Joyce-Kilmer/ SlickRock 1.205
1.061
1.035
1.029
0.923
0.793
0.764
0.686 1167.935; -418.371 1167.935; -418.371 1170.912; -417.942 1172.400; -417.727 1172.400; -417.727 1167.935; -418.371 1172.400; -417.727 1170.167; -418.050 223 0h
291 0h
239 0h
224 0h
179 0h
185 0h
238 0h
236 0h 16 4

Cohutta 0.639
0.577
0.501 0.414 1127.219; -475.399 1132.719; -476.504 1119.974; -478.260 1131.482, -484.260 253 0h
239 0h
254 0h 221 0h 3 0Air Quality Modeling Methodology 5-9 

### Table 5-7. Results for visibility impact using Method 6 – Wet Scrubber scenario - year 2001

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 2.053
1.169
0.973
0.923
0.803
0.800
0.740
0.691 1175.701; -398.594 1178.139; -394.509 1178.139; -394.509 1178.139; -396.509 1176.920; -396.551 1172.995; -400.852 1176.920; -396.551 1176.920; -396.551 365 0h
33 0h
360 0h
66 0h
9 0h
82 0h
1 0h
54 0h 16 2

Joyce-Kilmer/ Slickrock 0.419 1167.935; -418.371 224 0h 0 0



### Table 5-8. Results for visibility impact using Method 6 – Wet Scrubber scenario - year 2002

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.108
0.865
0.671
0.666
0.644
0.629
0.530
0.520 1176.920; -396.551 1181.107; -394.076 1169.066; -405.151 1169.066; -405.151 1175.435; -396.767 1192.709, -390.508 1174.216, -398.810 1178.139, -394.509 336 h0
295 h0
321 h0
54 h0
199 h0
285 h0
13 h0
12 h0 10 1

Joyce-Kilmer/ Slickrock 0.478 1170.167; -418.050 321 h0 0 0



### Table 5-9. Results for visibility impact using Method 6 – Wet Scrubber scenario - year 2003

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.858
1.089
1.067
0.917
0.849
0.820
0.709
0.702 1179.889; -396.119 1174.216; -398.810 1176.920; -396.551 1174.216; -398.810 1175.435; -396.767 1172.995; -400.852 1169.066; -405.151 1175.435; -396.767 12 h0
24 h0
83 h0
224 h0
16 h0
179 h0
223 h0
291 h0 18 3

Joyce-Kilmer/ Slickrock 0.432 1167.935; -418.371 223 h0 0 0Air Quality Modeling Methodology 5-10 

### Table 5-10. Results for visibility impact using Method 8 – Wet Scrubber scenario - year 2001

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.895
1.082
0.872
0.870
0.765
0.743
0.649
0.598 1175.701; -398.594 1178.139; -394.509 1178.139; -394.509 1178.139; -394.509 1176.920; -396.551 1172.995; -400.852 1176.920; -396.551 1178.404; -396.335 365 0h
33 0h
66 0h
360 0h

9 0h
82 0h
54 0h
86 0h 13 2

Joyce-Kilmer/ Slickrock 0.350 1167.935; -418.371 224 0h 0 0



### Table 5-11. Results for visibility impact using Method 8 – Wet Scrubber scenario - year 2002

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.018
0.722
0.612
0.600
0.548
0.522 0.477 1176.920; -396.551 1181.107, -394.076 1169.066, -405.151 1169.066, -405.151 1175.435; -396.767 1192.709, -390.508 1178.139, -394.509 336 h0
295 h0
54 h0
321 h0
199 h0
285 h0 12 h0 6 1

Joyce-Kilmer/ Slickrock 0.419 1170.167; -418.050 320 h0 0 0



### Table 5-12. Results for visibility impact using Method 8 – Wet Scrubber scenario - year 2003

Class I area Highest Extinction Change (dv) Receptor location day No. of days above 0.5dv No. of days above 1dv

Great Smoky Mountains 1.739
1.015
0.997
0.790
0.770
0.702
0.596
0.585 1179.889, -396.119 1174.216, -398.810 1176.920, -396.551 1175.435, -396.767 1174.216, -398.810 1172.995, -400.852 1169.066, -405.151 1175.435, -396.767 12 h0
24 h0
83 h0
16 h0
224 h0
179 h0
223 h0
291 h0 13 2

Joyce-Kilmer/ Slickrock 0.362 1167.935, -418.371 223 h0 0 0Air Quality Modeling Methodology 5-11 

### Table 5-13. Summary Table of Results at the 98 th 

### percentile change in light extinction for the Base Case Runs for Method 6 and Method 8

Values > 0.5 dv for Great Smoky

Mountain NP Values > 0.5 dv for Linville Gorge W. Values > 0.5 dv for Shining Rock W. Values > 0.5 for Joyce-Kilmer/ SlickRock W. Values > 0.5 for Cohutta W.

2001 No Yes Yes No Yes
2002 No Yes Yes No Yes Initial Run – Method 6
2003 No Yes Yes No Yes
2001 No Yes Yes Yes Yes
2002 No Yes Yes No Yes Initial Run – Method 8
2003 No Yes Yes No Yes



### Table 5-14. Summary Table of Results at the 98 th 

### percentile change in light extinction for the control scenario for Method 6 and Method 8

Values > 0.5 dv for Great Smoky Mountain NP Values > 0.5 for Joyce-Kilmer/ SlickRock W.
2001 No Yes
2002 No Yes Wet Scrubber – Method 6
2003 No Yes
2001 No Yes
2002 Yes Yes Wet Scrubber – Method 8
2003 No YesAir Quality Modeling Methodology5-12Table 5-15. Base Case Run - Source group and species contributions at the 8thhighest light extinction change (98thpercentile) for GreatSmoky Mountains National Park using CALPOST Method 6.Year Soure Group Contrib. toModeled ExtTotal Bext SO4 NO3 PM_Fine PM_Coarse Organics E. Carbon SO4 NO3 PM_Fine PM_Coarse OrganicsChange(%) 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm % % % % %Initial run, receptor 541, day ending 33 h02001 All Groups 100 2.903 0.648 0.153 0.317 0.146 1.639 0 22.32 5.27 10.92 5.03 56.462001 Potrooms L01-L04 53.88 1.564 0.009 0 0.297 0.123 1.135 0 0.58 0.00 18.99 7.86 72.572001 A398 P01-P04 29.90 0.868 0.466 0.007 0.006 0.007 0.382 0 53.69 0.81 0.69 0.81 44.012001 Bake P05-P10 13.99 0.406 0.173 0.107 0.003 0.003 0.121 0 42.61 26.35 0.74 0.74 29.802001 Crusher P11 0.10 0.003 0 0 0 0.003 0 0 0.00 0.00 0.00 100.00 0.002001 Reclamation Delacquering P12 1.17 0.034 0 0.03 0.002 0.002 0 0 0.00 88.24 5.88 5.88 0.002001 Melting Furnace P13-14 0.96 0.028 0 0.009 0.009 0.009 0.001 0 0.00 32.14 32.14 32.14 3.57Initial run, receptor 541, day ending 238 h02002 All Groups 100 2.699 2.409 0.004 0.031 0.014 0.24 0 89.26 0.15 1.15 0.52 8.892002 Potrooms L01-L04 5.45 0.147 0.012 0 0.026 0.01 0.099 0 8.16 0.00 17.69 6.80 67.352002 A398 P01-P04 80.66 2.177 2.051 0.001 0.002 0.002 0.122 0 94.21 0.05 0.09 0.09 5.602002 Bake P05-P10 13.56 0.366 0.344 0.002 0.001 0 0.019 0 93.99 0.55 0.27 0.00 5.192002 Crusher P11 0.04 0.001 0 0 0 0.001 0 0 0.00 0.00 0.00 100.00 0.002002 Reclamation Delacquering P12 0.15 0.004 0.002 0.001 0 0 0 0 50.00 25.00 0.00 0.00 0.002002 Melting Furnace P13-14 0.19 0.005 0 0 0.002 0.002 0 0 0.00 0.00 40.00 40.00 0.00Initial run, receptor 542, day ending 76 h02003 All Groups 100 3.76 3.496 0.022 0.024 0.012 0.207 0 92.98 0.59 0.64 0.32 5.512003 Potrooms L01-L04 2.87 0.108 0.013 0 0.018 0.006 0.071 0 12.04 0.00 16.67 5.56 65.742003 A398 P01-P04 76.41 2.873 2.765 0.001 0.002 0.001 0.104 0 96.24 0.03 0.07 0.03 3.622003 Bake P05-P10 20.32 0.764 0.715 0.016 0.001 0.001 0.031 0 93.59 2.09 0.13 0.13 4.062003 Crusher P11 0.03 0.001 0 0 0 0.001 0 0 0.00 0.00 0.00 100.00 0.002003 Reclamation Delacquering P12 0.16 0.006 0.002 0.003 0 0 0 0 33.33 50.00 0.00 0.00 0.002003 Melting Furnace 0.19 0.007 0 0.001 0.003 0.002 0 0 0.00 14.29 42.86 28.57 0.00Species Contribution to Modeled Extinction Coefficient in 1/Mm Percentage of Species Contribution to Modeled ExtinctionCAir Quality Modeling Methodology5-13Table 5-16. Base Case Run - Source group and species contributions at the 8thhighest light extinction change (98thpercentile) for GreatSmoky Mountains National Park using CALPOST Method 8.Year Soure Group Contrib. toModeled ExtTotal Bext SO4 NO3 PM_Fine PM_Coarse Organics NO2 SO4 NO3 PM_Fine PM_Coarse OrganicsChange(%) 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm 1/Mm % % % % %Initial run, receptor 108, day begining 223 h02001 All Groups 100 2.611 2.396 0.004 0.032 0.011 0.167 0.001 91.77 0.15 1.23 0.42 6.402001 Potrooms L01-L04 5.71 0.149 0.021 0 0.028 0.008 0.092 0 14.09 0.00 18.79 5.37 61.742001 A398 P01-P04 80.66 2.106 2.038 0 0.001 0.001 0.065 0 96.77 0.00 0.05 0.05 3.092001 Bake P05-P10 13.18 0.344 0.331 0.002 0 0 0.01 0 96.22 0.58 0.00 0.00 2.912001 Crusher P11 0.00 0 0 0 0 0 0 0 0.00 0.00 0.00 0.00 0.002001 Reclamation Delacquering P12 0.11 0.003 0.002 0.001 0 0 0 0 66.67 33.33 0.00 0.00 0.002001 Melting Furnace P13-14 0.11 0.003 0 0 0.002 0.001 0 0 0.00 0.00 66.67 33.33 0.00Initial run, receptor 541, day begining 237 h02002 All Groups 100 2.296 2.041 0.004 0.031 0.014 0.204 0.002 88.89 0.17 1.35 0.61 8.892002 Potrooms L01-L04 5.66 0.13 0.01 0 0.026 0.01 0.084 0 7.69 0.00 20.00 7.69 64.622002 A398 P01-P04 80.31 1.844 1.736 0 0.002 0.002 0.103 0 94.14 0.00 0.11 0.11 5.592002 Bake P05-P10 13.50 0.31 0.29 0.002 0.001 0 0.016 0.001 93.55 0.65 0.32 0.00 5.162002 Crusher P11 0.04 0.001 0 0 0 0.001 0 0 0.00 0.00 0.00 100.00 0.002002 Reclamation Delacquering P12 0.17 0.004 0.001 0.001 0 0 0 0.001 25.00 25.00 0.00 0.00 0.002002 Melting Furnace P13-14 0.22 0.005 0 0 0.002 0.002 0 0 0.00 0.00 40.00 40.00 0.00Initial run, receptor 543, day begining 250 h02003 All Groups 100 3.209 2.782 0.022 0.052 0.026 0.317 0.009 86.69 0.69 1.62 0.81 9.882003 Potrooms L01-L04 6.86 0.22 0.014 0 0.044 0.018 0.144 0 6.36 0.00 20.00 8.18 65.452003 A398 P01-P04 74.60 2.394 2.239 0.002 0.003 0.003 0.146 0.001 93.53 0.08 0.13 0.13 6.102003 Bake P05-P10 17.61 0.565 0.52 0.013 0.001 0.001 0.026 0.005 92.04 2.30 0.18 0.18 4.602003 Crusher P11 0.03 0.001 0 0 0 0.001 0 0 0.00 0.00 0.00 100.00 0.002003 Reclamation Delacquering P12 0.37 0.012 0.002 0.006 0.001 0.001 0 0.003 16.67 50.00 8.33 8.33 0.002003 Melting Furnace 0.31 0.01 0 0.002 0.004 0.003 0 0.001 0.00 20.00 40.00 30.00 0.00Species Contribution to Modeled Extinction Coefficient in 1/Mm Percentage of Species Contribution to Modeled ExtinctionCReferences 6-1 

## 6. REFERENCES

Allwine, K.J. and C.D. Whiteman, 1985: MELSAR: A mesoscale air quality model for complex terrain: Volume 1--Overview, technical description and user's guide. Pacific Northwest Laboratory, Richland, Washington.

Carson, D.J., 1973: The development of a dry, inversion-capped, convectively unstable boundary layer. Quart. J. Roy. Meteor. Soc., 99 , 450-467.

Douglas, S. and R. Kessler, 1988: User's guide to the diagnostic wind model. California Air Resources Board, Sacramento, CA.

Earth Tech, 2001. Mustang Energy Company, L. L. C. Mustang Electric Generating Station, Unit # 1, McKinley County, New Mexico. Class I Air Quality Modeling Protocol, Concord, MA.

FLAG, 2000. Federal Land Manager' Air Qu ality Related Values Workgroup (FLAG). Phase I Report. U.S. Forest Service, Nati onal Park Service, U.S. Fish and Wildlife Service.

Holtslag, A.A.M. and A.P. van Ulden, 1983: A simple scheme for daytime estimates of the surface fluxes from routine weather data. J. Clim. and Appl. Meteor., 22 , 517-529.

Liu, M.K. and M. A. Yocke, 1980: Siting of wind turbine generators in complex terrain. J. Energy, 4 , 10:16.

Mahrt, L., 1982: Momentum Balance of Gr avity Flows. Journal of Atmos. Sci., 39 , 2701- 2711.

Maul, P.R., 1980: Atmospheric transport of sulfur compound pollutants. Central Electricity Generating Bureau MID/SSD/80/0026/R. Nottingham, England.

O'Brien, J.J., 1970: A note on the vertical struct ure of the eddy exchange coefficient in the planetary boundary layer. J. Atmos. Sci., 27 , 1213-1215.

Perry, S.G., D.J. Burns, L.H. Adams, R.J. Paine, M.G. Dennis, M.T. Mills, D.G. Strimaitis,

R.J. Yamartino, E.M. Insley, 1989: User's Guide to the Complex Terrain Dispersion Model Plus Algorithms for Unstable Situa tions (CTDMPLUS) Volume 1: Model Description and User Instructions. EPA/600/8-89/041, U.S. Environmental Protection Agency, Research Triangle Park, NC.

Scire, J.S. and F.R. Robe, 1997: Fine-Scale Application of the CALMET Meteorological Model to a Complex Terrain Site. Pape r 97-A1313. Air & Waste Management Association 90th Annual Meeting & Exhibiti on, Toronto, Ontario, Canada. 8-13 June 1997.References 6-2 

### Scire, J.S., D.G. Strimaitis, and R.J. Yamar tino, 2000a: A User’s Guide for the CALPUFF Dispersion Model (Version 5). Earth Tech, Inc., Concord, MA

Scire, J.S., F.R. Robe, M.E. Fernau, and R. J. Yamartino, 2000b: A User’s Guide for the CALMET Meteorological Model (Version 5) . Earth Tech, Inc., Concord, MA.

Smrz, R., 1998: Updated Class I Receptor Li st and SLVs. Tennessee Department of Environment and Conservation, Division of Air Pollution Control, Nashville, TN. April 6, 1998.

Stelson, A. W. and J. H. Seinfeld, 1982: Re lative humidity and temperature dependence of the ammonium nitrate dissociation constant. Atmos. Environ., 16 , 983-992.

U.S. Department of Agriculture (USDA) Forest Service, Screening Methodology for Calculating ANC Change to High Elevati on Lakes, User’s Guide dated January 2000.

U.S. Environmental Protection Agency (EPA), 1998: Interagency Workgroup on Air Quality Modeling (IWAQM), Phase 2 Report: Summary Report and Recommendation for Modeling Long Range Transport and Impacts on Regional Visibility. EPA-454/R-98-019.

U.S. Environmental Protection Agency (EPA), 2000: Federal Register Notice dated April 21, 2001.

U.S., Environmental Protection Agency (EPA ), 2003: Guidance for Estimating Natural Visibility Conditions Under the Regional Haze Program. EPA-454/B-03-005, September 2003.

VISTAS, 2005: Protocol for the Application of the CALPUFF Model for Analysis of Best Available Retrofit Technology (BART).

# Appendix A CALPOST Visibility Method 8

The revised visibility algorithm deve loped for the IMPROVE Steering Committee (IMPROVE 2005) has been implemented in CALP OST. It differs from the previous IMPROVE algorithm in 6 areas:

1. Extinction efficiencies of sulfates, nitrat es, and organics vary with concentration, as there are distinct efficiencies for "sma ll" and "large" partic les and the ratio of small-to-large particle fraction decreases as the concentration increases. Furthermore, the extinction efficiency for sulfates no longer equals that for nitrates. 2. A separate hygroscopic humidity enhan cement factor curve is prescribed for "small" and "large" particles, f S 

### (RH) and f L 

### (RH). These curves apply to sulfates and nitrates. 3. Light extinction due to scat tering by sea salt (with its own hygroscopic humidity enhancement factor f SS 

### (RH)) is included. 4. Light absorption by NO 2 

### gas is included in the extinction. 5. Background particulate organic matter c oncentration is taken to be 1.8 times measured organic carbon concentrations. 6. Rayleigh scattering extinction varies with site elevati on and mean temperature.
Items 5 and 6 remain direct inputs to CALPOS T, and require no struct ural changes to the postprocessor. The user mu st confirm that appropri ate values are provided.
Item 4, the introduction of light extinction due to NO 2 

### gas absorption, has been added to CALPOST as a discrete com ponent independent of the visibility method chosen. New control file inputs associated with NO 2 

### are:

Modeled species to be included in computing the light extinction Include NO2 absorption? (LVNO2) -- Default: F ! LVNO2 = T ! With Visibility Method 8 -- Default: T

Source of NO2 (when LVNO2=T) may be from CALPUFF NO2 concentrations and from a fraction of CALPUFF NOx concentrations. Specify the fraction of NOx that is treated as NO2. (FNO2NOX) -- Default: 1.0 ! FNO2NOX = 0.75 !

Extinction Efficiency (1/Mm per ug/m**3)

---------------------------------------- NO2 GAS (EENO2) -- Default: .17 ! EENO2 = .17 !



### Items 1 through 3 are implemented as visibi lity method 8 in CALPOST, along with the specific choice of the new f(RH) curves. Selection of the revised IMPROVE algorithm requires the following new c ontrol file selections:Particle growth curve f(RH) for hygroscopic species (MFRH) -- Default: 2 ! MFRH = 4 !

1 = IWAQM (1998) f(RH) curve (originally used with MVISBK=1) 2 = FLAG (2000) f(RH) tabulation 3 = EPA (2003) f(RH) tabulation 4 = IMPROVE (2006) f(RH) tabulations for sea salt, and for small and large SULFATE and NITRATE particles; Used with Visibility Method 8 (MVISBK = 8)

Method used for background light extinction (MVISBK) -- Default: 2 ! MVISBK = 8 !

1 = Supply single light extinction and hygroscopic fraction 2 = Compute extinction from speciated PM measurements (A) 3 = Compute extinction from speciated PM measurements (B) 4 = Read hourly transmissometer background extinction measurements 5 = Read hourly nephelometer background extinction measurements 6 = Compute extinction from speciated PM measurements 7 = Use observed weather or prognostic weather information for background extinction during weather events; otherwise, Method 2 8 = Compute extinction from speciated PM measurements using the IMPROVE (2006) variable extinction efficiency formulation (MFRH must be set to 4) - Split between small and large particle concentrations of SULFATES, NITRATES, and ORGANICS is a function of concentration and different extinction efficiencies are used for each - Source-induced change in visibility includes the increase in extinction of the background aerosol due to the change in the extinction efficiency that now depends on total concentration. - Fsmall(RH) and Flarge(RH) adjustments for small and large particles are applied to observed and modeled sulfate and nitrate concentrations - Fsalt(RH) adjustment for sea salt is applied to background sea salt concentrations - F(RH) factors are capped at F(RHMAX) - RH for F(RH) may be obtained from hourly data as in Method 2 or from the FLAG monthly RH adjustment factor as in Method 6 where EPA F(RH) tabulation is used to infer RH. Furthermore, the monthly RH factor may be applied to hourly concentrations or daily concentrations to obtain the 24-hour extinction. These choices are made using the M8_MODE selection.

Additional inputs used for MVISBK = 8:

-------------------------------------- Extinction coefficients for hygroscopic species (modeled and background) may be computed using hourly RH values and hourly modeled concentrations, or using monthly RH values inferred from the RHFAC adjustment factors and either hourly or daily modeled concentrations.

(M8_MODE) -- Default: 3 ! M8_MODE= 3 !

1 = Use hourly RH values from VISB.DAT file with hourly modeled and monthly background concentrations. 2 = Use monthly RHFAC with EPA (2003) f(RH) tabulation with hourly modeled and monthly background concentrations. (VISB.DAT file is NOT needed). 3 = Use monthly RHFAC with EPA (2003) f(RH) tabulation with daily modeled and monthly background concentrations.(VISB.DAT file is NOT needed).

Background extinction coefficients are computed from monthly CONCENTRATIONS of sea salt (BKSALT). Month 1 is January. (ug/m**3)

(BKSALT) -- No default ! BKSALT= 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0 !



### The last of these selections, M8_MODE, pr ovides options for how concentrations are averaged, and how the relative humidity enha ncement factors for hygroscopic species are determined. M8_MODE has a default value of 3, selecting the use of monthly relative humidity factors (RHFAC), and using these with daily modeled concentration averages and monthly background concentrations. This default is consistent with an implementation of the revised IMPROVE al gorithm in the form of a spreadsheet processor (Tombach, 2006).
The revised IMPROVE algorithm mode ls the extinction (1/Mm) as:

] [ 17

. 0 ) ( ] [ 6

. 0 ] [ ) ( 7

. 1 ] [ 1 ] [ 10 ] arg [ 1

. 6 ] [ 8

. 2 ] arg [ ) ( 1

. 5 ] [ ) ( 4

. 2 ] arg [ ) ( 8

. 4 ] [ ) ( 2

. 2

2 

### NO specific site scattering Rayleigh matter coarse salt sea RH f soil fine carbon

elemental organics e l organics small nitrate e l RH f nitrate small RH f sulfate e l RH f sulfate small RH f b

SS L S L S ext



### • + − + • + • + • + • + • + • + • + • + • + • =

(1)

All of the brackets [] de note concentrations in μ g/m 3 

### . Note that Tombach (2006) uses an extinction efficiency for NO 2 

### of 0.33 (1/Mm)/(ppb), and requires NO 2 

### concentrations in ppb. This efficiency is equivalent to 0.17 (1/Mm)/( μ g/m 3 

### ) at standard pressure and 20°C.
Curves of f(RH) for both "small" and "large " particles, and sea salt particles are compared to the f(RH) for the EPA(2003) tabulation in Figure 1.
For sulfates, nitrates, and organics, "small" particles dominate the size distribution at small concentrations, and "large" particle s dominate the size di stribution at large concentrations. This is modeled as a simple linear relation from zero to the concentration at which the "small" particles essentially vanish, [C V 

### ]. Denoting the fraction of the concentration [C] (sulfates, nitrates, or organics) made up of "large" particles as F L 

### , and the fraction made up of "small" particles as F S 

### ,L S V L



### F F C C MIN F

− = =

0

. 1 ) ] [ ] [

, 0

. 1 ( (2)

The vanishing-point concentration [C V 

### ] is 20 μ g/m 3 

### for each of these species. The corresponding concentrations to be used in Eqn. 1 are

] [ ] arg [ ] [ ] [ C F e l C F small

L S



### • = • = (3)

Because the extinction efficiency for sulfates, nitrates, or organics depends on the total concentration of each, the tota l light extinction cannot be ca lculated as the sum of the background extinction (without the source contri bution) and the source-related extinction (without the background contribu tion). It is not a linear relationship. When source emissions increase the concentration at a r eceptor, the resulting total concentration changes the extinction efficiency, which applies to both the source-related concentration and the background concentration. The source impact on visibility is computed as the difference between the total extinction due to both the source emissions and background concentration, b ext,T 

### , and the extinction due to background concentrations alone, b ext,B 

### .

### Figure 1. Comparison of the f(RH) extinc tion enhancement factors for hygroscopic particles. The revised IMPROVE visibi lity algorithm replaces the EPA(2003) curve with individual curves for small and large part icles, and it introduces a curve for fine sea salt particles. f(RH) Curves

0 1 2 3 4 5 6 7 8 9 10

0 10 20 30 40 50 60 70 80 90 100 

### RHf(RH) 

### EPA(2003) Small Particles Large Particles Sea Salt

### Appendix C
WET SCRUBBER ECONOMIC AND ENERGY IMPACT

### Appendix D
BUSINESS CONFIDENTIAL INFORMATION