# CALPUFF Modeling Report for BART Analysis at Alcoa Inc. – Wenatchee Facility in Washington

September 2007

Prepared For:

Alcoa Wenatchee, Washington

Submitted By:

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

### TABLE OF CONTENTS

Page

1.0 INTRODUCTION ................................................................................................................... ...1-1

2.0 GEOPHYSICAL AND METEO ROLOGICAL DATA ..........................................................2-1

3.0 MODELING SIMULATI ONS FOR BART.............................................................................3-1

3.1 Terrain ........................................................................................................................ ..............3-1
3.2 Land Use....................................................................................................................... ............3-5
3.3 Meteorological Data Base ....................................................................................................... .3-5
3.4 Air Quality Monitoring Data ..................................................................................................3- 13

4.0 AIR QUALITY MODELING OPTIONS SELECTED...........................................................4-1

4.1 Modeling Domain Configuration and Receptors......................................................................4-1
4.2 Meteorological Modeling Options............................................................................................4-1
4.3 Dispersion Modeling Options...................................................................................................4 -4
4.4 Visibility Calculations ........................................................................................................ ......4-5

5.0 RESULTS ........................................................................................................................ ............5-1

6.0 REFERENCES..................................................................................................................... .......6-1iii 

### LIST OF FIGURES

Page

Figure 3-1 Terrain contours (m MSL) at 4 km resolution used in the screening runs. The Class I areas within the black circle (300 km radius around Wenatchee facility) were modeled in the screening runs. ...............................................................................................3- 3 Figure 3-2 Terrain contours at 500m resolution on the 209 km x 143 km CALMET/CALPUFF modeling domains. Locations of the fac ility and the Alpine Lakes Class I area modeled in the refined r uns are also shown. ..........................................................................3-4 Figure 3-3 Dominant land use categories at 500m resolution on the 209 km x 143 km CALMET/CALPUFF modeling domains. Locations of the facility and the Alpine Lakes Class I area modeled in the refined runs are also shown. ............................................3-6 Figure 3-4 Locations of surface meteorological stations and MM5 data points used in the 2003- 2005 modeling. The facility lo cation is also shown. ............................................................3-12 Figure 3-5 AIRS ozone stations used in the 2003, 2004 and 2005 refined modeling. The facility location is also shown......................................................................................................... ..3-15 Figure 4-1 Locations of receptors at Al pine Lakes Class I area. .............................................................4-3iv 

### LIST OF TABLES

Page

Table 2-1 Line Sources Emission Rates Used in CALPUFF .................................................................2-2

Table 2-2 Parameters Used for Modeling Line Sources.........................................................................2-2
Table 2-3 Point Source Parameters........................................................................................................ .2-3
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 Sources and Parameters Used...............................................................3-9
Table 3-4 NWS Hourly Surface Stations for 2003, 2004 and 2005 .....................................................3-10

Table 3-5 Ozone Stations for 20 03, 2004 and 2005 .............................................................................3-14

Table 4-1 20% Best Visibility Days Conditions Levels of Aerosol Components ( μ g/m 3 

### ) to define natural background ...................................................................................................... 4-7
Table 4-2 Monthly Site-Specific f(RH) Values Based on the Class I Centroid for Application to Visibility Method 6 ............................................................................................................ ....4-7
Table 5-1 Summary Table for Visibility Impacts in the Screening Modeling........................................5-2

Table 5-2 Summary Table for Visibility Impact s in the Refined Modeling...........................................5-21-1 

## 1.0 INTRODUCTION

TRC Environmental Corporation conducted s ite-specific BART (Best Available Retrofit Technology) modeling for Alcoa Wenatchee prim ary aluminum reduction facility located on the bank of Columbia River, eleven miles southeast of the city of Wenatchee, Chelan County, Washington, to determine if BART-eligible sources of this facility are subject to controls. This analysis followed the Modeling Protocol for Washington, Oregon, and Idaho: Protocol for the Application of the CALPUFF Modeling System Pursuant to the Best Available Retrofit Technology (BART) Regulation , dated November 2006, hereafte r referred to as Washington Protocol, 2006 with several modifications as detailed in this report.

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

BART review is required when the source emits any air pollutant which may reasonably be anticipated to cause or contribute to any impa irment of visibility in any Class I 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 en ergy and non-air quality environmental impacts of compliance, (c) any existing pollution control tec hnology 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 was to assess the visibility impacts of sulfur dioxide (SO 2 

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

### ) emissions from the sources which are BARTeligible and compare their impacts to the 0.5 cha nge in deciview (dv) threshold at all federally mandatory Class I areas within 300 kilometers fro m the Wentachee facility sources. A total of eleven Class I areas are located within this radius : Alpine Lakes Wilderness (W), Goat Rocks W, Glacier Peak W, Mount Adams W, Mount Rainier National Park (NP), North Cascades NP, Olympic NP, Pasayten W, Mount Hood W, Mount Jefferson W, Eagle Cap W, as well as Columbia River Gorge Scenic Area (SA). A scree ning run on the 4 km resolution domain, with CALMET files that were provided by Washington state has determined that the 98 th 

### percentile of change in light extinction shown exceedance of a 0.5 deciview screening threshold only at one Class I area – Alpine Lakes Wilderness. This Cl ass I area is subject to further analysis. The refined modeling simulations on a higher resolution (500m) grid were then conducted to evaluate in detail the impacts at the Alpine Lakes Class I area.1-2 

### The topography of the screening domain area consists of ocean on its west side with sea-land boundaries. The Cascades Range, whose peaks can reach more than 3,000 meters, crosses the domain from the north to the southeastern part of the domain. The Olympic Mountains South also reach 2000 meters. The Wenatchee facility is locat ed on the bank of Columbia River in the bottom of the valley surrounded by high hills. As a result, there is a strong potential for terrain effects on the meteorological fields and in term s of plume-terrain interaction effects. A nonsteady-state modeling approach is useful in this assessment to properly evaluate the air quality impacts of the facility’s sources. The CALMET and CALPUFF non-steady-state models (Scire etal., 2000a,b) are recommended in the Washington BART Protocol (2006) to perform sourcespecific subject-to-BART screening analysis. The CALMET/CALPUFF models were also used for the refined modeling analysis of the Alpine Lakes Class I area. The U.S. Environmental Protection Agency (U.S. EPA) has promulgated the CALPUFF modeling system as a Guideline Model for Class I impact assessments and other long range transport applications or on a case-bycase basis for near-field applicati ons involving complex flows (U.S. EPA, 2003a), and the model is recommended by both the Federal Land Mana gers Air Quality Workgroup (FLAG, 2000) and the Interagency Workgroup on Air Quality Modeling (IWAQM, 1998). CALPUFF is specifically recommended by the U.S. EPA for BART analyses ( Federal Register , 6 July 2005).

For the screening runs, CALMET.DAT files were provided by the U.S. EPA Region X. Screening modeling was performed in May 2007 and used the codes recommended by Washington BART Protocol and the EPA, i.e., CALPUFF (Versi on: 6.112, Level: 060412) and CALPOST (Version 6.131, Level 060410) .

A new regulatory version of CALM ET and CALPUFF was approved by the U.S. EPA on June 29, 2007. In the refined runs conducted in July-A ugust, 2007, one of the deviations from the Washington BART Protocol was an update in th e version of model codes used. The latest regulatory versions of CALMET (Version 5.8, Level 070623), CALPUFF (Version 5.8, Level 070623) and CALPOST (Version 5.6394, Level 070622) approved by the U.S. EPA were used in the refined modeling.

CALMET is a diagnostic meteorological model that produces three-dimensional wind fields based on parameterized treatments of terrain e ffects such as slope flows and terrain blocking effects. Meteorological observations are used to determine the wind field in areas where the observations are representative. Hourly meteor ological data produced by the Mesoscale Model, Version 5 (MM5) on a 12 km grid are used in CALMET for all three years 2003, 2004 and 2005 to define the initial guess wind fields before CA LMET’s terrain adjustments is computed. The MM5 datasets were prepared by Geomatrix and were provided by the U.S. EPA Region X for use in this BART analysis. The CALMET simulations, on a 4 km grid resolution domain prepared for Washington, Oregon and Idaho states were used in the screening analysis. In the refined analysis for the Alpine Lakes Class I area, a smaller dom ain on a higher resolution 500m grid was used to better resolve the terrain effects on the wind and pollutant dispersion.

CALPUFF is a non-steady-state puff dispersion mode l. It accounts for spatial changes in the CALMET-produced meteorological fields, variab ility in surface conditions (elevation, surface roughness, vegetation type, etc.), chemical transf ormation, wet removal due to rain and snow, dry1-3 

### deposition, and terrain in fluences on plume interaction with the surface. CALPUFF contains a module to compute visibility effects, based on a humidity-dependent relationship between particulate matter concentrations and light ex tinction, as well as wet and dry acid deposition fluxes. The screening and refined meteorologi cal and dispersion modeling simulations are conducted for a three-year period (2003, 2004 and 2005). SO 2 

### , PM, and NO x 

### emissions and their secondary products resulting from chemical c onversions from the Alcoa Wenatchee were modeled at receptors in the Class I areas and their impacts on visibility were evaluated.

This report outlines the techniques and data used in the BART analyses. A screening modeling was conducted in accordance with the procedures outlined in the Washington modeling protocol (2006) using the 4 km Domain provided by the W ashington Department of Ecology. The refined analysis on a higher resolution domain is described in this site-specific report. 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 (meteorol ogical, geophysical, and aerometric) used in the analysis are provided in Section 3. Section 4 includes an overview of the CALMET and CALPUFF models, and the parameters used in the analysis. The results are summarized in Section 5.2-1 

## 2.0 GEOPHYSICAL AND METEOROLOGICAL DATA

The Alcoa Wenatchee facility is an aluminum re duction plant situated eleven miles southeast of the city of Wenatchee, Chelan County, Washington, and one and one half miles north of the Rock Island Dam on the Columbia River.

A BART applicability analysis was completed by Alcoa for the facility to determine those sources subject to the BART controls. The BA RT-eligible sources include one potline and ten additional point sources. The 24-hour average actual emission rates of SO 2 

### , NO x 

### and PM (PM 10 

### , filterable and condensable PM 2.5 

### ) with normal operations from the highest emitting day over the modeled period 2003-2005, consiste nt with the BART guideline, were used for this analysis.

The Washington BART Protocol indicates that building downwash can be ignored in the screening modeling at large source-receptor distances typically involved in the Class I analyses. All Class I areas are more than 50 km away from the facility, except for the Alpine Lakes which ranges from 43 km to 113 km from the facility. Si nce the Class I areas modeling in the current study are beyond or close to 50 km from the facility, building downwash was not included in the screening or refined modeling.

Table 2-1 lists the parameters and emission rat es for line sources. Table 2-2 shows parameters used in the buoyant line source plume rise calculations. Table 2-3 shows the source parameters and emission rates for the point sources.

For all sources, the particulate matter em issions are divided into three partitions:

(1) PM 10 

### - represented as the coarse particulates (PMC) for particulates in the size range of 2.5 micrometers ( μ m) to 10 μ m. Particles in this size range have a light extinction coefficient of efficiency of 0.6.

(2) The filterable PM 2.5 

### - represented as the fine particulates (PMF) equal to or less than 2.5 μ m. The PMF has a light extinction coefficient of efficiency of 1.0.

(3) The condensable PM 2.5 

### - represented as the organic condensable (SOA). SOA has a light extinction coefficient of efficiency of 4.0.

Note that since the size fraction is not provide d, the default values, based on information in CALPUFF User’s Guide and AP-42 was used as recommended in the Washington BART Protocol. PMC was modeled with a ge ometric mass mean diameter of 5 μ m, PMF and SOA with a geometric mass mean diameter of 0.5 μ m. PMC, PMF and SOA were modeled with a geometric standard deviation of 1.5 μ m.2-2Table 2-1 Line Sources Emission Rates Used in CALPUFFSourceDescriptionLineNo.LCCCoordinateBeg. X(km)LCCCoordinateBeg. Y(km)LCCCoordinateEnd X(km)LCCCoordinateEnd Y(km)ReleaseHeight(m)BaseElevation(m)PMC(PM10-PM2.5)EmissionRate (g/s)PMF(PM2.5)EmissionRate(g/s)SOA(OrganicCondensable)PM2.5EmissionRate (g/s)SO2EmissionRate(g/s)NOxEmissionRate(g/s)Potline #5,Room 20PL-0 63.853 -176.567 64.034 -176.331 14.80 203.9 0.16 0.22 0.215 0.14 0.001Potline #5,Room 22PL-0 63.880 -176.588 64.062 -176.353 14.80 203.9 0.16 0.22 0.215 0.14 0.0011Emission data is from spreadsheet “Wenatchee BART Modeling Inputs 3_23_07.xls”.Table 2-2 Parameters Used for Modeling Line SourcesBuilding DimensionsLine IDHeight Width LengthBuildingSeparationLine SourceWidthExit Velocity VolumetricFlowBuoyancy Parameter (F')per Line(m) (m) (m) (m) (m) m/s m3/sec (m4/s3)Potline #5, Room 2013.2 17.1 307.7 19.05 1.42 0.95 55.32 410.22Potline #5, Room 2213.2 17.1 307.7 19.05 1.42 0.95 55.32 410.222-3Table 2-3 Point Source ParametersIndex Source DescriptionLCC1Coord. X(km)LCC1Coord. Y(km)StackHeight(m)BaseElevation(m)EffectiveStackDiameter(m)ExitVelocity(m/s)ExitTemp.(K)PMCEmissionRate(g/s)PMFEmissionRate(g/s)SOAEmissionRate(g/s)SO2EmissionRate(g/s)NOxEmissionRate(g/s)PT05T Line5 GTC 64.105 -176.412 65.00 203.6 4.27 20.17 394 0.38 0.10 2.61 28.49 0.130IP-1 Ingot Furnace 1 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.048 0.136 0.088 0.0001 0.021IP-2 Ingot Furnace 2 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.050 0.142 0.092 0.0001 0.021IP-11 Ingot Furnace 11 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.090 0.255 0.165 0.0002 0.031IP12112Ingot Furnace 11 64.105-176.412 18.30 203.60.91 6.96 5220.188 0.5330.345 0.0004 0.073A446 A446 Bakes Scrub. 64.105 -176.412 15.24 203.6 0.91 10.30 339 0.0015 0.001 0.009 7.195 1.000DCS Dry Coke Scrubber 64.105 -176.412 18.29 203.6 1.22 6.29 311 0.0 0.040 0.0 0.0 0.0DUST Dust Collector 2 64.105 -176.412 14.33 203.6 1.02 4.49 293 0.0 0.330 0.0 0.0 0.0AL21M Alumina Handling 21M 64.105 -176.412 23.77 203.6 0.30336.56 293 0.0 0.010 0.0 0.0 0.0AL19C Alumina Handling 19C 64.105 -176.412 30.33 203.6 0.226414.51 293 0.0 0.010 0.0 0.0 0.0AL43E Alumina Handling 43E 64.105 -176.412 15.24 203.6 1.68 4.00 293 0.0 0.480 0.0 0.0 0.01The LCC projection is based on standard parallels of 30.0 N and 60.0 N, an origin latitude and longitude of 49.0 N and 121.0 W,and datum NWS-84. Location of the sourcePT05T, provided in “Wenatchee BART Modeling Inputs 3_23_07.xls”, expressed in UTM coordinates with NAD27 datum is 717.450 km, 5248.500 km. For the modelingpurposes, other 8 point sources were co-located with PT05T.2For modeling purposes, combinedIngot Furnaces IP-1, IP-2 and IP-11 to a single point source adding emissions from all three sources.3Rectangular point source AL21M (0.24m x 0.30m) modeled with equivalent stack diameter with same area.4Rectangular point source AL19C (0.20m x 0.20m) modeled with equivalent stack diameter with same area.3-1 

## 3.0 MODELING SIMULATIONS FOR BART

A set of screening runs of BART-eligible sources at the Alcoa Wentachee facility were performed for 2003-2005 using the 4 km resolution CALMET.DAT files provided by the U.S. EPA Region X. Eleven Class I areas, Alpine Lakes W, Goat Rocks W, Glaci er Peak W, Mount Adams W, Mount Rainier NP, North Cascades NP, Olympic NP, Pasayten W, Mount Hood W, Mount Jefferson W, Eagle Cap W, as well as Columbia River Gorge SA are located with in the 300 km radius around the facility as it is displayed in Figure 3-1. The black circle is the 300 km limit around the Wenatchee facility showing the Class I areas included in the screening analysis. The vi sibility analysis was pe rformed as described in Washington BART Protocol, using Method 6 and 20 th 

### percentile best day natural background values. The 8 th 

### highest visibility impacts (the 98 th 

### percentile) for each Class I area were compared against the 0.5 dv screening threshold. The on ly Class I area where the 8 th 

### highest visibility impact exceeded the 0.5 dv threshold was Alpine Lakes Wilderness, th e Class I area closest to the facility. The 98 th 

### percentile impacts at Alpine Lakes in the screening analysis were 0.353, 0.662 and 0.660 change in deciview for 2003, 2004 and 2005, respectively (Table 5-1). As a result, th e Alpine Lakes Wilderness was subject to a refined modeling analysis. Because of the complexity of the terrain around the Wenatchee facility, a refined run with higher grid resolution was pe rformed as described hereafter.

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 Defense Mapping Agency using cartographic and photographic sources. USGS 1:250,000 scale topographic maps are the primary source of 1-degree DEMs.

One degree DEM data consists of an array of 1 201 by 1201 elevations referenced on the geographic (latitude/longitude) coordinate system of the Worl d 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-seconds, which corresponds to a spacing of approximately 90 meters.

The CALMET computational domain for the refined run has horizontal resolution of 500m. This domain covers an area of 209 km by 143 km (Figur e 3-2) which Wenatchee facility, Alpine Lakes Wilderness and the 50 km buffer zone in each direc tion from the facility and the Class I area. Terrain in this region is complex, varying from 200m elevation in the vicinity of the facility to 2,500m elevation at some peaks at Alpine Lakes. It is important to no te that Alcoa Wenatchee fa cility is located in the Columbia River valley. Southerly flow can be ch anneled through the valley north and northwest from the facility. About 20 km northwest from the f acility, the valley branches northeast following the Columbia River basin and northwest towards the Alpine Lakes. Figure 3-2 shows contours of the terrain averaged to 500m. The USGS elevation records lo cated within each grid cell in the computational domain are averaged to produce a mean elevation at each grid point. Adequa te representation of the important terrain features and valleys associated with the Class I area and the surrounding area are captured by the 418 x 268 grid cells, a workable number of cells. The CALPUFF computational domain3-2 

### is the same as the CALMET domain. The CALM ET and CALPUFF domain extends beyond the Class I area and the facility in order to provide an adequa te buffer zone at the boundaries, and to allow the effects of flow curvature and possible small-scale recirculation to be evaluated.3-3 

### Figure 3-1 Terrain contours (m MSL) at 4 km resoluti on used in the screening runs. The Class I areas within the black circle (300 km radius around Wenatch ee facility) were modeled in the screening runs.

-400 -200 0 200 400 600 800 LCC X (km) -800 -600 -400 -200 0 200LCC Y (km)

40.N 42.N 44.N 46.N 48.N 50.N 128.W 126.W 124.W 122.W 120.W 118.W 116.W 114.W 112.W 110.W 108.W

-10 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 4500

Terrain (m) Olympic NP

North Cascades NP Pasayten W

Glacier Peak W

Alpine Lakes W

Mount Rainier NP

Goat Rocks W
Mount Adams W

Mt Jefferson W Eagle Cap W Mt Hood W Columbia River Gorge

LCC Origin: 49N,121W Matching Paralles: 30N, 60N Datum: NWS-84 Wenatchee3-4 

### Figure 3-2 Terrain contours at 500m resolution on the 209 km x 143 km CALMET/CALPUFF modeling domains. Locations of the facility and the Alpine La kes Class I area modeled in the refined runs are also shown.

-80 -60 -40 -20 0 20 40 60 80 100 LCC X (km) -220 -200 -180 -160 -140 -120 -100LCC Y (km) Alpine Lakes

Wenatchee Elevations (m)

LCC Coordinates NWS84 Datum Origin: 49N,121W Lat: 30N, 60N -10 100 300 500 700 900 1100 1300 1500 1700 1900 2100 2300 2500 2700 2900 3100 3300 3500 3700 3900 45003-5 

### 3.2 Land Use

The USGS land use data within the CALMET/CALP UFF computational domain have been used to produce a gridded field of dominant land use categories. The land use data used in the analysis were obtained in Composite Theme Grid (CTG) format from the USGS, at a resolution of 200m.

Land use data were processed to produce a 500m resolution gridded field of fractional land use categories. The 37 USGS land use categories were then mapped into 14 CALMET land use categories. Surface properties such as albedo, Bowen ratio, rou ghness length, and leaf area index were computed proportionally to the 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 parameters. Figure 3-3 shows the dominant land use categories used in the modeling.

3.3 Meteorological Data Base

The CALMET model requires meteorological information from the surface and upper air as well as geophysical information about the land use and terra in heights. Specifically, CALMET requires surface observations of wind speed, wind direction, temper ature, cloud cover, ceiling height, surface pressure, relative humidity, and precipitation t ype (e.g., snow, rain, etc.). These variables are routinely measured at the National Weather Service (NWS) surface stati ons. The upper air data needed includes twice-daily observations of vertical profiles of wind sp eed, wind direction, temperature, and pressure.

The CALMET refined modeling was run using NOOB S=1, as recommended in the Washington BART protocol. This means that upper air data were taken from MM5 and not from the twice-daily observations. Precipitation and relative humidity were also derived from the MM5 data. So, neither upper air nor precipitations observations were entere d in the model from direct observations. Table 3-3 lists the types of observational and m odeled data available that were used in the modeling. A total of 64 surface meteorological stations for each year were used in the refined run (Table 3-4). And threedimensional gridded data from th e prognostic numerical model MM5 run by Geomatrix for Washington, Oregon and Idaho states were also included with a resolution of 12 km for years 2003 through 2005. Observed cloud cover from the NWS surface stations w as used but the influence of the wind from the surface stations was reduced by using very small values of R1 and R2 in CALMET, as recommended in the Washington BART Protocol. This minimizes lo cal distortion to the MM5 wind fields. Hourly precipitation data, which are required for wet depos ition calculations in CALPUFF, were derived from the MM5 data.3-6 

### Figure 3-3 Dominant land use categories at 500m resolution on the 209 km x 143 km CALMET/CALPUFF modeling domains. Locations of the facility and the Alpine Lakes Class I area modeled in the refined runs are also shown. -80 -60 -40 -20 0 20 40 60 80 100 LCC X (km) -220 -200 -180 -160 -140 -120 -100LCC Y (km) Alpine Lakes

Wenatchee

LCC Coordinates NWS84 Datum Origin: 49N,121W Lat: 30N, 60N 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100
Snow/Ice

Tundra

Barren

Wetland

Water

Forest

Range

Agriculture

Urban/Built-Up3-7 

### 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 Glaciers3-8Table 3-2 Default CALMET Land Use Categoriesand 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 0.220 Agricultural 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 use3-9 

### Table 3-3 Meteorological Data Sources and Parameters Used

Type of Dataset Frequency Source Parameters

Surface observations Hourly NWS Wind speed, wind direction, ceiling height, cloud cover, relative humidity, surface pressure, precipitation type
Modeled Profiles MM5 for 2003, 2004 and 2005 Hourly U.S. EPA Region X Hourly, gridded fields of winds, temperature, pressure, and humidity and liquid water content on 12 km grid for 2003, 2004 and 2005.3-10 

### Table 3-4 NWS Hourly Surface Stations for 2003, 2004 and 2005

WMO INIT Station Name State Co untry Latitude Longitude Elevation (m) LCC X 1 (km) LCC Y 1 (km) 690230 KNUW Whidbey Island Nas WA US 48.35N 122.67W 10.1 -119.273 -68.636 711080 CYXX Abbotsford Airport CAN 49.03N 122.37W 58.0 -96.5984 4.05271 712030 CYLW Kelwna airport CAN 49.97N 119.38W 430.0 112.1774 105.5081 717990 CYYJ Victoria Intl. Airport. CAN 48.65N 123.43W 19.0 -172.561 -35.0142 71880 CYXC Cranbrook Airport CAN 49.6N 115.78W 939.0 363.8237 76.40979 718920 CYVR Vancouver Intl. Arpt. CAN 49.18N 123.17W 2.0 -152.558 21.42668 718930 CYQQ Comox (CAN-MIL) CAN 49.72N 124.9W 24.0 -271.279 84.06896 725864 KMYL McCall Arpt. ID US 44.88N 116.1W 1530.0 372.5602 -431.117
726810 KBOI Boise Air Terminal ID US 43.57N 116.22W 865.0 371.8409 -572.106 726813 KEUL Caldwell (AWOS) ID US 43.63N 116.63W 740.0 339.6282 -567.492
726817 KMLP Mullan Pass ID US 47.45N 115.67W 1829.0 386.8529 153.696 726830 KBNO Burns Municipal Apt OR US 43.6N 118.95W 1261.9 159.4664 -577.944
726835 KRDM Redmond Roberts Fl OR US 44.25N 121.17W 932.7 -13.0773 -510.155 726836 KSPB Scappoose Industria OR US 45.77N 122.85W 18.0 138.528 -345.368 726837 KONO Ontario Municipal OR US 44.02N 117.02W 667.5 307.2629 -527.232 726880 KPDT Pendleton E or reg. OR US 45.7N 118.83W 451.7 162.6882 -352.279 726881 KMMV McMinnville Mncp. OR US 45.2N 123.13W 159.0 -161.118 -406.02 726883 KHRI Hermistn muni Arpt. OR US 45.83N 119.27W 195.0 129.405 -339.129
726885 KMEH Meacham OR US 45.52N 118.42W 1134.8 19 4.0392 -370.681 726886 KBKE Baker Municipal Apt OR US 44.83N 117.82W 1026.6 242.0845 -443.081 726917 KOTH North Bend (AWOS) OR US 43.42N 124.25W 1.8 -253.555 -594.177 726930 KEUG Eugene Mh, Sweet Apt OR US 44.12N 123.22W 108.2 -171.139 -521.758 726940 KSLE Salem McNary Field OR US 44.9N 123W 59.7 -152.091 -438.473 726945 KCVO Corvallis Mncp AWOS OR US 44.5N 123.28W 75.0 -174.601 -480.836 726958 KONP Newport Municipal OR US 44.58N 124.05W 37.2 -233.215 -470.29
726959 KUAO Aurora State OR US 45.25N 122.77W 60.0 -133.773 -401.316 726980 KPDX Portland Intl. Arpt. OR US 45.6N 122.62W 5.8 -121.678 -363.988
726985 KTTD Portland/Troutdale OR US 45.55N 122.4W 11.0 -105.249 -369.667
726986 KHIO Portland/Hillsboro OR US 45 .53N 122.95W 62.0 -146.642 -370.949 726988 KDLS The Dalles Mncp Apt WA US 45.62N 121.15W 73.2 -11.2632 -363.061
727810 KYKM Yakima air terminal WA US 46.57N 120.55W 324.3 33.21619 -260.985 727825 KEAT Wenatchee/Pangborn WA US 47.4N 120.2W 379.0 58.15981 -171.656 727826 KEPH Ephrata AP FCWOS WA US 47.3N 119.52W 383.7 107.7898 -181.691
727827 KMWH Moses Lake/Grant CO WA US 47.2N 119.32W 364.5 122.5793 -192.141
727830 KLWS Lewiston Nez Perce C. ID US 46.37N 117.02W 437.7 294.7262 -275.225
727834 KCOE Coeur d’Alene AWOS IS US 47.77N 116.82W 707.0 301.6782 -124.326
727845 KPSC Pasco/Tri-Cities WA US 46.27N 119.12W 135.9 139.514 -291.65 727846 KALW Walla Walla City Cnt WA US 46.1N 118.28W 355.4 202.4497 -308.101 727850 KGEG Spokane Intl. Arpt WA US 47.62N 117.53W 718.1 251.1697 -142.873 727854 KDEW Deer Park Arpt WA US 47.97N 117.42W 672.0 257.446 -104.9583-11 

### Table 3-4 NWS Hourly Surface Stations for 2003, 2004 and 2005 (continued)

WMO INIT Station Name State Country Latitude (deg.) Longitude (deg.) Elevation (m) LCC X 1 (km) LCC Y 1 (km)
727855 KSKA Fairchild AFB WA US 47.62N 117.65W 743.1 242.4888 -143.242 727856 KSFF Spokane/Felts field WA US 47.68N 117.32W 595.0 266.0636 -135.755 727857 KPUW Pullman/Moscow Rg WA US 46.75N 117.12W 778.0 285.3506 -234.836 727883 KELN Ellensburg/Bowers WA US 47.03N 120.53W 527.0 34.40251 211.583 727885 KCLM Port Angeles Intl. WA US 48.12N 123.5W 88.0 -179.308 -91.7976
727890 KOMK Omak WA US 48.42N 119.53W 382.0 104.8526 -61.3938 727910 KAST Astoria Regional Apt OR US 46.15N 123.88W 2.7 -214.16 -302.32
727918 KVUO Pearson Field OR US 45.62N 122.65W 8.0 -123.886 -361.795 727920 KOLM Olympia Airport WA US 46.97N 122.9W 62.8 -139.215 -216.475 727923 KHQM Hoquiam Airport WA US 46.98N 123.93W 3.7 -214.617 -213.126 727924 KKLS Kelso-Longvi. AWOS WA US 46.12N 122.9W 4.9 -141.38 -307.715
727928 KPWT Bremerton Int. AWOS WA US 47.5N 122.75W 147.0 -126.982 -159.818 727930 KSEA Seattle-Tacoma Int Apt WA US 47.47N 122.32W 121.9 -95.837 -163.638 727934 KRNT Renton Municipal WA US 47.5N 122.22W 9.0 -88.5281 -160.531 727935 KBFI Seattle/Boeing Fld WA US 47.53N 122.3W 6.1 -94.2804 -157.218
727937 KPAE Everett/Paine Field WA US 47.9N 122.28W 185.0 -92.1947 -117.499
727938 KTIW Tacoma Narrows WA US 47.27N 122.58W 89.0 -115.136 -184.773 727945 KAWO Arlington Municipal WA US 48.17N 122.17W 42.0 -83.8484 -88.6115 727970 KUIL Quillayute State Apt WA US 47.93N 124.57W 54.6 -256.919 -109.284 727976 KBLI Bellingham Int. Apt WA US 48.8N 122.53W 45.4 -108.351 -20.4709 727985 KFHR Friday Harbor WA US 48.52N 123.02W 33.0 -143.805 -49.7936
742060 KTCM Mc Chord AFB/Tacom WA US 47.13N 122.48W 88.1 -108.127 -199.945 718890 CYYF Penticton Arpt. CAN 49.47N 119.6W 344.0 97.88598 51.41323
727925 KSHN Shelton/Sanderson WA US 47.23N 123.15W 85.0 -156.779 -188.1

1 Lambert Conic Conformal (LCC) projection, LCC origin (49N, 121W), standard parallels (30N, 60N), datum NWS-84.3-12 

### Figure 3-4 Locations of surface meteorological sta tions and MM5 data point s used in the 2003-2005 modeling. The facility location is also shown. -300 -200 -100 0 100 200 300 LCC East (km) -500 -400 -300 -200 -100 0 100LCC North (km) KNUW CYXX

CYYJ CYXC

CYVR CYQQ

KMYL

KBOI KEUL KMLP

KBNO KRDM KSPB

KONO KPDT

KMMV KHRI

KMEH

KBKE

KOTH KEUG KSLE

KCVO KONP KUAO KPDX

KTTD KHIO KDLS KYKM KEAT KEPH KMWH

KLWS KCOE

KPSC KALW KGEG KDEW

KSKA KSFF

KPUW KELN KCLM KOMK

KAST

KVUO KOLM KHQM

KKLS KPWT KSEA KRNT KBFI KPAE

KTIW KAWO
KUIL KBLI

KFHR

KTCM CYYF

KSHN

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

(m)

LCC Coordinates NWS84 Datum Origin: 49N,121W Lat: 30N, 60N

Surface meteorological stations

2003, 2004 or 2005 MM5 gridded points (12km resolution) Wenatchee3-13 

### 3.4 Air Quality Monitoring Data

CALPUFF uses hourly ozone concentration measuremen ts in the chemical transformation rates (SO 2 

### to SO 4 

### , NO x 

### to HNO 3 

### /NO 3 

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

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

### loss rates to nitrate. Ambient ozone monitoring data for 2003, 2004 and 2005 were extrac ted from the U.S. EPA AIRS networks and were used to develop hourly ozone monitoring data files fo r each year of the modeling analysis. A total of 21 monitoring stations, listed in Table 3-5, were used in the modeling. Figure 3-5 shows the locations of each available station for the three years modeled. This is a refinement from the protocol, where a constant concentration of ozone of 60 parts per billion (ppb) is r ecommended. The 60 ppb concentration was used as backup when hourly oz one concentrations were missing.

A constant background ammonia concentration of 17 ppb as recommended in the Washington BART Protocol was used for CALPUFF run for every point and line source. Each source was run in a separate CALPUFF run and concentrations from all the sour ces runs were combined then in POSTUTIL.3-14 

### Table 3-5 Ozone Stations for 2003, 2004 and 2005

Network ID Land Use Latitude Longitude LCC X 1 (km) LCC Y 1 (km)

AIRS 410050004 Agricultural 45.259724N 122.587502W -119.961 -400.562 AIRS 410090004 Agricultural 45.768055N 122.771942W -132.689 -345.709 AIRS 410470004 Agricultural 44.809444N 122.913612W -145.755 -448.354
AIRS 410510080 Residential 45.496666N 122.602219W -120.564 -375.107
AIRS 530090012 Residential 48.097500N 123.425552W -174.044 -94.379
AIRS 530110011 Residential 45.616669N 122.516670W -113.884 -362.351
AIRS 530330010 Residential 47.551945N 122.044441W -75.717 -155.132
AIRS 530330017 Forest 47.489723N 121.773331W -56.128 -162.039
AIRS 530330023 Forest 47.141109N 121.933060W -68.157 -199.354 AIRS 530390003 Agricultural 45.664165N 120.999725W -0.053 -358.112
AIRS 530410007 Forest 46.624348N 121.386871W -28.528 -255.174
AIRS 530450005 Forest 47.418770N 122.849998W -134.438 -168.378
AIRS 530530012 Forest 46.785278N 121.732780W -53.877 -237.716
AIRS 530531008 Residential 46.843056N 122.317497W -96.763 -230.962
AIRS 530531010 Forest 46.761391N 122.121666W -82.504 -239.950
AIRS 530570013 Forest 48.539444N 121.446945W -31.810 -49.429
AIRS 530570018 Commercial 48.460102N 122.519112W -108.273 -57.019
AIRS 530630001 Unknown 47.422222N 117.530281W 252.070 -164.098
AIRS 530630046 Residential 47.827221N 117.275276W 268.559 -119.807
AIRS 530670002 Residential 46.936390N 122.610832W -118.103 -220.548 AIRS 530730005 Agricultural 48.953609N 122.564720W -109.770 -4.035

1 Lambert Conic Conformal (LCC) projection, LCC origin (49N, 121W), standard parallels (30N, 60N), datum NWS-84.3-15 

### Figure 3-5 AIRS ozone stations used in the 2003, 2 004 and 2005 refined modeling. The facility location is also shown. -200 -150 -100 -50 0 50 100 150 200 250 LCC East (km) -400 -350 -300 -250 -200 -150 -100 -50

0LCC North (km)

410050004 410090004

410470004 410510080 530090012

530110011 530330010 530330017

530330023

530390003 530410007 530450005

530530012 530531008 530531010 530570013 530570018

530630001 530630046

530670002

530730005

Snow/Ice

Tundra

Barren

Wetland

Water

Forest

Range

Agriculture

Urban/Built-Up

Land Use 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80 85 90 95 100

Wenatchee4-1 

## 4.0 AIR QUALITY MODELING OPTIONS SELECTED

4.1 Modeling Domain Configuration and Receptors

CALMET and CALPUFF use terrain-following coordinat es. In order to cover a large enough area for the refined analysis, a modeling domain of 418 x 286 gr id cells, uniform in the horizontal with a spatial resolution of 500m was used. In the vertical, a stretche d grid was used with finer resolution in the lower layers and somewhat coarser resolution aloft thus allowing adequate representation of the mixed layer. The ten vertical levels are centered at: 10, 30, 52. 5, 92.5, 160, 300, 550, 950, 1700, 2500 and 3100

meters.

The CALPUFF computational domain is the same as the CALMET computational domain. The modeling domain includes a buffer zone of at least 50 km from the source and beyond the borders of the Class I area. This minimizes the edge effects and a llow pollutants involved in flow reversals to be brought back into the Class I areas. CALPUFF was run for three years, 2003, 2004 and 2005.

The receptor locations along with receptor elevati ons were available from the National Park Service (NPS). The distribution of the receptors within Alpi ne Lakes Class I area is shown in Figure 4-1.

4.2 Meteorological Modeling Options

In the refined CALMET simulations, the regulat ory option was used (MREG=1), indicating the selection of the mixing height method (IMIXH=-1 using the Maul-Carson method over land and the OCD method over water; ICOARE=0 using the OCD me thod for turbulence and fluxes over water; and THRESHL=0.0 using a value of zero for the threshol d sensible heat flux over land). In the screening runs, the CALMET.DAT files as provided by EPA Regi on X were used in the analysis. The screening CALMET simulations were conducte d using the CALMET switch settings described in the Washington BART Protocol.

Initial Guess Field

MM5 data were used to define the initial guess fi eld for the CALMET simulations. For all three years hourly MM5 data with a horizontal grid spacing of 12 km and 31 vertical levels were used as the initial guess wind field.

Step 1 Field: Terrain Effects

In developing the Step 1 wind field, CALMET adjust s the initial guess field to reflect kinematic effects of the terrain, slope flows and blocking effects. Slope flows are a function of the local slope and altitude of the nearest crest. The crest is defined as the hi ghest peak within a radius TERRAD around each grid point. A value of TERRAD of 12 km, as recommended in the Washington BART Protocol was used in the CALMET simulations. The Step 1 field produces a flow field consistent with the fine-scale CALMET terrain resolution (500m).4-2 

### 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 final 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 obs ervation site, the Step 1 wind field and the surface observations are weighted equally. RMAX1 and RMAX2 were set to large values (200 km), while small values of R1 and R2 (1.0 x 10 -6 

### km) were used in order to limit the influence of observations on the grid to retain the flow characteristics of the terrain-adjusted MM5 winds.4-3 

### Figure 4-1 Locations of receptors at Alpine Lakes Class I area.4-4 

### 4.3 Dispersion Modeling Options

The CALPUFF simulations were conducte d using the following model options:

- Gaussian near-field distribution - Transitional plume rise - No building downwash - Pasquill-Gifford (PG) dispersion coefficients (rural areas), and McElroy-Pooler coefficients (urban areas) - Transition of σ y 

### to time-dependent (Heffter) growth rates - Partial plume path adjustment for terrain - Puff splitting will not be used, followi ng the recommendations of the FLMs - Wet deposition, dry deposition, and chemical transformation using the MESOPUFF II scheme - Regulatory options used.

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

Two important computational para meters 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 were set to 1.0 in the CALPUFF simulations in order to allow the strong wind channeling effects to be accounted for in th e puff trajectory calculations. The first parameter ensures that the length of an emitted puff does not be come so large so that it cannot respond to changes in the wind field on the scale of the meteorologi cal grid. The model automatically increases the frequency of puff releases to ensure the length of a si ngle 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 incorporates the effect of the te rrain on the plume trajectories. The plume path coefficient is used to characteri ze the local effect on ground-level concentrations. The default plume path coefficients (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 effects were modeled using the defau lt dry deposition model, the scavenging coefficient wet removal module, and th e default chemical transformation mechanism. A total of eight species were modeled with CALPUFF for this analysis: SO 2 

### , SO 4 

### , NO x 

### , HNO 3 

### , NO 3, 

### and three subcategories of PM 10 

### , (PMC, PMF, SOA). Of these eight species, five were emitted by the Alcoa sources: SO 2 

### , NO x 

### , PMC, PMF and SOA. The chemical mechanism computes transformation rates of4-5 

### SO 2 

### to SO 4 

### and NO x 

### to NO 3 

### /HNO 3 

### . Hourly measured ozone concentra tions are provided in an external OZONE.DAT file for use with the chemical transf ormation module. These ozone concentrations, along with radiation intensity, are used as surrogates fo r the OH concentration during the day when the gas phase free radical chemistry is active.

To allow for flexibility each source was modeled i ndividually and the source concentrations were summed at the end in postprocessing steps.

4.4 Visibility Calculations

Calculations of the impact of the simulated plume particulate matter component concentrations on light extinction is carried out in the CALPOST postpro cessor. The procedures are consistent with the Washington BART Protocol (2006). In this analysis , the original IMPROVE/EPA equation is applied to determine the change in light extinction due to changes in component concentrations. Using the notations of CALPOST, 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 Guidance for Estimating Natural Visibility Conditions under the Regional Haze Progr am (U.S. EPA, 2003b). Note that organic carbon (OC), which consists of conden sable particulates, was modeled as SOA in CALPUFF runs. Soil represents the fine particulates which were defi ned as PMF in the CALPUFF run, while Coarse Mass was labeled PMC.

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 b ext 

### is in Mm -1 

### . The impact of a source is determined by comparing HI for estimated natural background conditi ons with the impact of the source and without the impact of the source

.


### CALPOST Method 6 was used to compute the extincti on change in deciviews consistent with the procedures outlined in the Washington BART Protocol.

A monthly background concentration must be entere d into the CALPOST input control file for all aerosols defining the background. The 20% best days fo r each of the eleven Clas s I areas were used for the natural background extinction calculations in the screening runs. The natural background concentrations for the 20% best days ha s been refined from that which is in Guidance for Estimating Natural Visibility Conditions U nder the Regional Haze Program (U.S. EPA, 2003b). The extinction coefficients for the 20% best days have been cal culated following the approach taken in the Draft Montana BART modeling protocol. This procedure uses the haze index (HI) in deciviews at the 10th percentile (median of the 20% best days) and an activ ity factor that is calculated for each Class I area.4-6 

### Therefore, the natural background concentrations used for each of the eleven Class I areas and one Scenic Area are summarized in Table 4-1.

Table 4-2 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 are extracted from Appendix A of Guidance for Estimating Natural Visibility Conditions Under the Regional Haze (U.S. EPA, 2003b).

The 8 th 

### highest (98 th 

### percentile) predicted light extinction cha nge for each year modeled was compared to the threshold value of 0.5 dv. As presented in S ection 5, predicted visibility impacts for all Class I areas except the Alpine Lakes were below the 0.5 dv threshold. Therefore, Eagle Cap Wilderness, Glacier Peak Wilderness, Goat Ro cks Wilderness, Mount Adams Wild erness, Mount Hood Wilderness, Mount Jefferson Wilderness, Mount Rainier Nationa l Park, North Cascades National Park, Olympic National Park, Pasayten Wilderness, Columbia Ri ver Gorge Scenic Area are all exempt for the remainder of the BART process based on the screeni ng analysis. The impact of the Alcoa Wenatchee BART sources in the screening run was above 0.5 dv at Alpine Lakes for two of the three years modeled. Therefore, refined modeling on the 500m hor izontal grid was performed for this Class I Area.4-7 

### Table 4-1 20% Best Visibility Days Conditions Levels of Aerosol Components ( μ g/m 3 

### ) to define natural background

Class I Area SO 4 NO 3 OC EC Soil Coarse Mass Alpine Lakes W. 0.054 0.045 0.212 0.009 0.225 1.35

Eagle Cap W. 0.049 0.041 0.203 0.008 0.203 1.22
Glacier Peak W. 0.054 0.045 0.21 0.009 0.223 1.34
Goat Rocks W. 0.054 0.045 0.21 0.009 0.224 1.34
Mount Adams W. 0.053 0.044 0.209 0.009 0.222 1.33
Mount Hood W. 0.053 0.044 0.209 0.009 0.222 1.33
Mount Jefferson W. 0.054 0.045 0.213 0.009 0.226 1.36
Mount Rainier NP 0.055 0.045 0.214 0.009 0.227 1.36
North Cascades NP 0.053 0.044 0.209 0.009 0.222 1.33 Olympic NP 0.054 0.045 0.213 0.009 0.226 1.36 Pasayten W. 0.053 0.044 0.208 0.009 0.222 1.33 Columbia River Gorge SA 0.569 0.231 1.05 0.205 0.217 0.485
Source: Guidance for Estimating Natural Visi bility Conditions Under th e Regional Haze Program (S eptember 2003), Table 2-1, adjusted to speciated particulate (Western States) to reflect 20% Best Visi bility Days conditions.



### Table 4-2 Monthly Site-Specific f(RH) Values Based on the Class I Centroid for Application to Visibility Method 6

Class I area Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec Alpine Lakes W. 4.25 3.79 3.47 3.90 2.93 3.22 2.92 3.12 3.25 3.91 4.47 4.51

Eagle Cap W. 3.77 3.16 2.47 2.10 2.04 1.87 1.61 1.56 1.61 2.25 3.44 3.97

Glacier Peak W. 4.16 3.72 3.42 3.75 2.91 3.16 2.88 3.14 3.33 3.90 4.42 4.43

Goat Rocks W. 4.25 3.75 3.36 4.24 2.83 3.38 3.03 3.19 3.07 3.77 4.42 4.55

Mount Adams W. 4.29 3.80 3.44 4.40 2.92 3.49 3.12 3.27 3.13 3.86 4.49 4.56

Mount Hood W. 4.29 3.81 3.46 3.87 2.95 3.15 2.85 3.00 3.10 3.86 4.53 4.55

Mount Jefferson W. 4.41 3.90 3.56 3.74 3.07 3.11 2.89 2.91 3.03 3.78 4.55 4.54

Mount Rainier NP 4.42 3.96 3.64 4.65 3.06 3.69 3.30 3.50 3.40 4.11 4.66 4.66

North Cascades NP 4.10 3.69 3.43 3.74 2.93 3.20 2.93 3.23 3.45 3.93 4.39 4.38
Olympic NP 4.51 4.08 3.82 4.08 3.17 3.46 3.12 3.48 3.71 4.38 4.83 4.75
Pasayten W. 4.17 3.72 3.41 3.72 2.89 3.16 2.88 3.15 3.32 3.86 4.42 4.46
Columbia River Gorge SA 5.03 5.03 2.59 2.59 2.59 2.59 2.11 2.11 2.11 3.51 3.51 5.03

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

Table A-3.5-1 

## 5.0 RESULTS

The change in light extinction relativ e to the natural background due to SO 2 

### , NO x 

### and PM 10 

### from Wenatchee BART eligible sources was computed base on the emission levels described in Section 2, for modeling years 2003-2005. The emissions levels for the base case are presented in Table 2-1 to Table 2-3. The CALPUFF modeling predicted the effects of emissions from the Wenatchee units on visibility at the eleven Class I areas and one Scenic Area within 300 km of the facility. The BART methodology with CALPOST Method 6 based on the 98 th 

### percentile day results was used to determine visibility impacts. The light extinction impacts are presented for each modeled year in units of change in deciview for each Class I area, consistent with the pr ocedures outlined in the Washington Protocol.

Table 5-1 summarize the maximum and eighth highest (98 th 

### percentile) predicted extinction changes for 2003-2005, based on the screening modeling for 11 Class I areas and one Scenic Area. The screening results show that the 98 th 

### percentile visibility impacts from Wena tchee facility are below the screening threshold of 0.5 deciview at all of the modeled Cl ass I or sensitive areas except for the Alpine Lakes Wilderness Area.

Refined modeling with a higher resolution meteorol ogical grid was conducted for the Alpine Lakes Class I area. Table 5-2 shows the maximum and 98 th 

### percentile predicted extinction changes for 2003- 2005 based on the high resolution modeling. The predicted impacts on the worst 98 th 

### percentile day during the three annual periods is 0.379 deciview, which is well below the 0.5 screening threshold. Therefore, the conclusion from the modeling analysis is that the Alcoa Wenatchee facility is not subject to BART controls.5-2 

### Table 5-1 Summary Table for Visibility Impacts in the Screening Modeling

Class I Area Maximum Δ dv 8 th H Δ dv 98 th percentile Maximum Δ dv 8 th H Δ dv 98 th percentile Maximum Δ dv 8 th H Δ dv 98 th percentile

2003 2004 2005
Alpine Lakes W. 0.706 0.353 1.271 0.662 1.168 0.660

Eagle Cap W. 0.355 0.187 0.397 0.169 0.531 0.218
Glacier Peak W. 0.398 0.218 0.463 0.329 0.554 0.293
Goat Rocks W. 0.314 0.128 0.253 0.128 0.380 0.196
Mount Adams W. 0.270 0.132 0.316 0.168 0.300 0.191
Mount Hood W. 0.239 0.105 0.263 0.175 0.218 0.155
Mount Jefferson W. 0.096 0.068 0.264 0.071 0.124 0.061
Mount Rainier NP 0.269 0.131 0.375 0.216 0.233 0.154
North Cascades NP 0.290 0.102 0.289 0.088 0.168 0.105 Olympic NP 0.129 0.060 0.160 0.055 0.094 0.037 Pasayten W. 0.083 0.044 0.191 0.052 0.065 0.031 Columbia River Gorge SA 0.418 0.104 0.157 0.096 0.209 0.121



### Table 5-2 Summary Table for Visibilit y Impacts in the Refined Modeling

Class I Area Maximum Δ dv 8 th H Δ dv 98 th percentile Maximum Δ dv 8 th H Δ dv 98 th percentile Maximum Δ dv 8 th H Δ dv 98 th percentile

2003 2004 2005
Alpine Lakes W. 0.640 0.200 0.845 0.379 0.535 0.3076-1 

## 6.0 REFERENCES

FLAG, 2000. Federal Land Manager' Air Quality Related Values Workgroup (FLAG). Phase I Report. U.S. Forest Service, National Park Servi ce, U.S. Fish and Wildlife Service.

Scire, J.S., D.G. Strimaitis, and R.J. Yamartino, 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.

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), 2003a: Revision to the Guideline on Air Quality Models: Adoption of a Preferred Long Range Transport Mo del and Other Revisions; Final Rule. 40 CRF 51. Federal Register , April 15, 2003, 68 , 72, pp 18440-18482.

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

Washington, Oregon, Idaho Protocol for the Applica tion of the CALPUFF Modeling System Pursuant to the Best Available Retrofit Technology (BART) Regulation, November 2006