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) 970-5600 
ii

TABLE OF CONTENTS 

Page

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

2.0 GEOPHYSICAL AND METEOROLOGICAL DATA ..........................................................2-1

3.0 MODELING SIMULATIONS 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............................................................................................................................6-1
iii

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 facility and the Alpine Lakes Class I area 

modeled in the refined runs 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 location 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 Alpine Lakes Class I area. .............................................................4-3
iv

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 2003, 2004 and 2005 .............................................................................3-14

Table 4-1 20% Best Visibility Days Conditions Levels of Aerosol Components (μg/m3) 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 Impacts in the Refined Modeling...........................................5-2
1-1

1.0 INTRODUCTION 

TRC Environmental Corporation conducted site-specific BART (Best Available Retrofit 

Technology) modeling for Alcoa Wenatchee primary 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, hereafter 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 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 Federallyprotected parks and wilderness areas, commonly referred to as “Class I 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 tons or more of a visibility-impairing air 

pollutant, were put in place between August 7, 1962 and August 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 source emits any air pollutant which may reasonably be 

anticipated to cause or contribute to any impairment 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 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 was to assess the visibility impacts of sulfur dioxide (SO2), 

particulate matter (PM) and nitrogen oxides (NOx) emissions from the sources which are BARTeligible and compare their impacts to the 0.5 change in deciview (dv) threshold at all federally 

mandatory Class I areas within 300 kilometers from 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 screening run on the 4 km resolution domain, with 

CALMET files that were provided by Washington state has determined that the 98th 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 Class 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 located 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 terms 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 et 

al., 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 applications involving complex flows (U.S. EPA, 2003a), and the model 

is recommended 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 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 (Version: 6.112, Level: 060412) and CALPOST (Version 

6.131, Level 060410) . 

A new regulatory version of CALMET and CALPUFF was approved by the U.S. EPA on June 29, 

2007. In the refined runs conducted in July-August, 2007, one of the deviations from the 

Washington BART Protocol was an update in the 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 effects 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 meteorological 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 CALMET’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 domain 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 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 
1-3

deposition, and terrain influences 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 extinction, as well as wet and dry acid deposition 

fluxes. The screening and refined meteorological and dispersion modeling simulations are 

conducted for a three-year period (2003, 2004 and 2005). SO2, PM, and NOx emissions and their 

secondary products resulting from chemical conversions 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 Washington 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 (meteorological, 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 reduction 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 BART-eligible sources include one potline and ten 

additional point sources. The 24-hour average actual emission rates of SO2, NOx and PM (PM10, 

filterable and condensable PM2.5) with normal operations from the highest emitting day over the 

modeled period 2003-2005, consistent 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. Since 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 rates 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 emissions are divided into three partitions: 

(1) PM10 - represented as the coarse particulates (PMC) for particulates in the size range of 

2.5 micrometers (μm) to 10 μm. Particles in this size range have a light extinction coefficient of 

efficiency of 0.6. 

(2) The filterable PM2.5 - represented as the fine particulates (PMF) equal to or less than 2.5 μm. 

The PMF has a light extinction coefficient of efficiency of 1.0. 

(3) The condensable PM2.5 - 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 provided, 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 geometric mass mean diameter of 5 μm, PMF and SOA with 

a geometric mass mean diameter of 0.5 μm. PMC, PMF and SOA were modeled with a geometric 

standard deviation of 1.5 μm. 
2-2

Table 2-1 Line Sources Emission Rates Used in CALPUFF 

Source 

Description 

Line 

No. 

LCC 

Coordinate 

Beg. X 

(km) 

LCC 

Coordinate 

Beg. Y 

(km) 

LCC 

Coordinate 

End X 

(km) 

LCC 

Coordinate 

End Y 

(km) 

Release 

Height 

(m) 

Base 

Elevation 

(m) 

PMC 

(PM10-

PM2.5) 

Emission 

Rate (g/s)

PMF 

(PM2.5) 

Emission 

Rate 

(g/s) 

SO

(Org

Conden

PM

Emis

Rate 

Potline #5, Room 20 PL-0 63.853 -176.567 64.034 -176.331 14.80 203.9 0.16 0.22 0.2Potline #5, Room 22 PL-0 63.880 -176.588 64.062 -176.353 14.80 203.9 0.16 0.22 0.2

1 Emission data is from spreadsheet “Wenatchee BART Modeling Inputs 3_23_07.xls”. 

Table 2-2 Parameters Used for Modeling Line Sources 

Line ID Building Dimensions 

Height Width Length 

Building 

Separation 

Line Source 

Width 

Exit Velocity Volumetric 

Flow 

 (m) (m) (m) (m) (m) m/s m3/sec 

Potline #5, Room 20 13.2 17.1 307.7 19.05 1.42 0.95 55.32 Potline #5, Room 22 13.2 17.1 307.7 19.05 1.42 0.95 55.32 
2-3

Table 2-3 Point Source Parameters 

Index Source Description LCC1

Coord. X 

 (km) 

LCC1

Coord. Y

(km) 

Stack 

Height

(m) 

Base 

Elevation 

(m) 

Effective 

Stack 

Diameter 

(m) 

Exit 

Velocity 

(m/s) 

Exit 

Temp. 

(K) 

PMC 

Emission 

Rate 

(g/s) 

PMF 

Emission 

Rate 

(g/s)

PT05T Line5 GTC 64.105 -176.412 65.00 203.6 4.27 20.17 394 0.38 0.10 

IP-1 Ingot Furnace 1 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.048 0.136 IP-2 Ingot Furnace 2 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.050 0.142 

IP-11 Ingot Furnace 11 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.090 0.255 

IP12112 Ingot Furnace 11 64.105 -176.412 18.30 203.6 0.91 6.96 522 0.188 0.533 

A446 A446 Bakes Scrub. 64.105 -176.412 15.24 203.6 0.91 10.30 339 0.0015 0.001 

DCS Dry Coke Scrubber 64.105 -176.412 18.29 203.6 1.22 6.29 311 0.0 0.040 

DUST Dust Collector 2 64.105 -176.412 14.33 203.6 1.02 4.49 293 0.0 0.330 

AL21M Alumina Handling 21M 64.105 -176.412 23.77 203.6 0.3033 6.56 293 0.0 0.010 

AL19C Alumina Handling 19C 64.105 -176.412 30.33 203.6 0.2264 14.51 293 0.0 0.010 

AL43E Alumina Handling 43E 64.105 -176.412 15.24 203.6 1.68 4.00 293 0.0 0.480 

1 The 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 datu

PT05T, provided in “Wenatchee BART Modeling Inputs 3_23_07.xls”, expressed in UTM coordinates with NAD27 datum is 717.450 km

purposes, other 8 point sources were co-located with PT05T. 

2 For modeling purposes, combined Ingot Furnaces IP-1, IP-2 and IP-11 to a single point source adding emissions from all three sources. 3 Rectangular point source AL21M (0.24m x 0.30m) modeled with equivalent stack diameter with same area. 4 Rectangular 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, Glacier 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 within 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 visibility analysis was performed as described in 

Washington BART Protocol, using Method 6 and 20th percentile best day natural background values. The 

8th highest visibility impacts (the 98th percentile) for each Class I area were compared against the 0.5 dv 

screening threshold. The only Class I area where the 8th highest visibility impact exceeded the 0.5 dv 

threshold was Alpine Lakes Wilderness, the Class I area closest to the facility. The 98th 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, the 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 performed 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 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-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 (Figure 3-2) which Wenatchee facility, Alpine Lakes 

Wilderness and the 50 km buffer zone in each direction 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 note that Alcoa Wenatchee facility is located in the 

Columbia River valley. Southerly flow can be channeled through the valley north and northwest from 

the facility. About 20 km northwest from the facility, 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 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 418 x 268 grid cells, a workable number of cells. The CALPUFF computational domain 
3-2

is the same as the CALMET domain. The CALMET and CALPUFF domain extends beyond the Class I 

area and the facility 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.
3-3

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. 

-400 -200 0 200 400 600 800

LCC X (km)

-800

-600

-400

-200

0

200

LCC 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 

Wenatchee
3-4

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 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

-100

LCC 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

4500
3-5

3.2 Land Use 

The USGS land use data within the CALMET/CALPUFF 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, roughness 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 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 measured 

at the National Weather Service (NWS) surface stations. The upper air data needed includes twice-daily 

observations of vertical profiles of wind speed, wind direction, temperature, and pressure. 

The CALMET refined modeling was run using NOOBS=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 entered in the model from direct observations. Table 3-3 

lists the types of observational and modeled 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 the 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 was 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 local distortion to the MM5 wind fields. Hourly 

precipitation data, which are required for wet deposition 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

-100

LCC 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-Up
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 

Glaciers 
3-8

Table 3-2 Default CALMET Land Use Categories and Associated Geophysical Parameters based on the U.S. Geo

Classification System (14-Category System) 

Land Use Type Description Surface 

Roughness (m)

Albedo Bowen Ratio Soil Heat 

Flux Parameter

Anthropo

Heat Flux (

10 Urban or Built-up Land 1.0 0.18 1.5 .25 0.0 20 Agricultural Land - 

Unirrigated 

0.25 0.15 1.0 .15 0.0 

-20* Agricultural Land - Irrigated 0.25 0.15 0.5 .15 0.0 

30 Rangeland 0.05 0.25 1.0 .15 0.0 

40 Forest Land 1.0 0.10 1.0 .15 0.0 50 Water 0.001 0.10 0.0 1.0 0.0 54 Small Water Body 0.001 0.10 0.0 1.0 0.0 55 Large Water Body 0.001 0.10 0.0 1.0 0.0 60 Wetland 1.0 0.10 0.5 .25 0.0 61 Forested Wetland 1.0 0.1 0.5 0.25 0.0 62 Nonforested Wetland 0.2 0.1 0.1 0.25 0.0 70 Barren Land 0.05 0.30 1.0 .15 0.0 80 Tundra .20 0.30 0.5 .15 0.0 90 Perennial Snow or Ice .05 0.70 0.5 .15 0.0 

* Negative values indicate "irrigated" land use 
3-9

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 Country Latitude Longitude Elevation 

(m) 

LCC X1

(km) 

LCC Y1

(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 1134.8 194.0392 -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 -104.958 
3-11

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 X1

(km) 

LCC Y1

(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 stations and MM5 data points 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

100

LCC North (km)

KNUW

CYXX

CYYJ

CYXC

CYVR

CYQQ

KMYL

KEULKBOI

KMLP

KBNO

KRDM

KSPB

KONO

KPDT

KMMV

KHRI

KMEH

KBKE

KOTH

KEUG

KSLE

KCVO KONP

KUAO

KPDX KHIO KTTD KDLS

KYKM

KEAT KEPH

KMWH

KLWS

KCOE

KPSC

KALW

KGEG

KDEW

KSKAKSFF

KPUW

KELN

KCLM

KOMK

KAST

KVUO

KHQM KOLM

KKLS

KPWTKSEA KBFI KRNT

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)

Wenatchee
3-13

3.4 Air Quality Monitoring Data 

CALPUFF uses hourly ozone concentration measurements in the chemical transformation rates (SO2 to 

SO4, NOx to HNO3/NO3). The ambient ozone measurements were used in determining SO2 loss rates 

due to chemical transformation to sulfate and in determining NOx loss rates to nitrate. Ambient ozone 

monitoring data for 2003, 2004 and 2005 were extracted from the U.S. EPA AIRS networks and were 

used to develop hourly ozone monitoring data files for 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 recommended. The 60 ppb concentration 

was used as backup when hourly ozone 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 sources 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 X1

(km)

LCC Y1

(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, 2004 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

0

LCC 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

Wenatchee
4-1

4.0 AIR QUALITY MODELING OPTIONS SELECTED 

4.1 Modeling Domain Configuration and Receptors 

CALMET and CALPUFF use terrain-following coordinates. In order to cover a large enough area for 

the refined analysis, a modeling domain of 418 x 286 grid cells, uniform in the horizontal with a spatial 

resolution of 500m was used. In the vertical, a stretched 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 allow 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 elevations were available from the National Park Service 

(NPS). The distribution of the receptors within Alpine Lakes Class I area is shown in Figure 4-1. 

4.2 Meteorological Modeling Options 

In the refined CALMET simulations, the regulatory 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 method for turbulence and fluxes over water; and 

THRESHL=0.0 using a value of zero for the threshold sensible heat flux over land). In the screening 

runs, the CALMET.DAT files as provided by EPA Region X were used in the analysis. The screening 

CALMET simulations were conducted using the CALMET switch settings described in the Washington 

BART Protocol. 

Initial Guess Field 

MM5 data were used to define the initial guess field 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 adjusts 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 highest 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 observation 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 conducted 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 σy to time-dependent (Heffter) growth rates 

- Partial plume path adjustment for terrain 

- Puff splitting will not be used, following 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 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 were 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 respond 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 incorporates the effect of the terrain on the plume trajectories. The plume path 

coefficient is used to characterize 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 default dry deposition model, 

the scavenging coefficient wet removal module, and the default chemical transformation mechanism. A 

total of eight species were modeled with CALPUFF for this analysis: SO2, SO4, NOx, HNO3, NO3, and 

three subcategories of PM10, (PMC, PMF, SOA). Of these eight species, five were emitted by the Alcoa 

sources: SO2, NOx, PMC, PMF and SOA. The chemical mechanism computes transformation rates of 
4-5

SO2 to SO4 and NOx to NO3/HNO3. Hourly measured ozone concentrations are provided 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. 

To allow for flexibility each source was modeled individually 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 postprocessor. 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: 

Bext = 3f(RH)[(NH4)2SO4] + 3f(RH)[NH4NO3] + 4[OC] + 1[Soil] + 0.6[Coarse Mass] +10[EC] + bray

The concentrations, in square brackets, are in μg/m3

 and bext is in units of Mm-1. The Rayleigh scattering 

term (bray) has a default value of 10 Mm-1, as recommended in EPA Guidance for Estimating Natural 

Visibility Conditions under the Regional Haze Program (U.S. EPA, 2003b). Note that organic carbon 

(OC), which consists of condensable particulates, was modeled as SOA in CALPUFF runs. Soil 

represents the fine particulates which were defined as PMF in the CALPUFF run, while Coarse Mass 

was labeled PMC. 

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

HI = 10 ln(bext/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 natural background conditions with the impact of the source and without the 

impact of the source. 

CALPOST Method 6 was used to compute the extinction change in deciviews consistent with the 

procedures outlined in the Washington BART Protocol. 

A monthly background concentration must be entered into the CALPOST input control file for all 

aerosols defining the background. The 20% best days for each of the eleven Class I areas were used for 

the natural background extinction calculations in the screening runs. The natural background 

concentrations for the 20% best days has been refined from that which is in Guidance for Estimating 

Natural Visibility Conditions Under the Regional Haze Program (U.S. EPA, 2003b). The extinction 

coefficients for the 20% best days have been calculated 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 activity 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 8th highest (98th percentile) predicted light extinction change for each year modeled was compared 

to the threshold value of 0.5 dv. As presented in Section 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 Rocks Wilderness, Mount Adams Wilderness, Mount Hood Wilderness, 

Mount Jefferson Wilderness, Mount Rainier National Park, North Cascades National Park, Olympic 

National Park, Pasayten Wilderness, Columbia River Gorge Scenic Area are all exempt for the 

remainder of the BART process based on the screening 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 horizontal grid was performed for this Class I Area. 
4-7

Table 4-1 20% Best Visibility Days Conditions Levels of Aerosol Components (μg/m3) to define 

natural background 

Class I Area SO4 NO3 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 Visibility Conditions Under the Regional Haze Program (September 2003), Table 2-1, 

adjusted to speciated particulate (Western States) to reflect 20% Best Visibility 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 Visibility Conditions Under the Regional Haze Program (September 2003), Appendix A, 

Table A-3.
5-1

5.0 RESULTS 

The change in light extinction relative to the natural background due to SO2, NOx and PM10 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 98th 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 procedures outlined in the Washington Protocol. 

Table 5-1 summarize the maximum and eighth highest (98th 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 98th percentile visibility impacts from Wenatchee facility are below the screening 

threshold of 0.5 deciview at all of the modeled Class I or sensitive areas except for the Alpine Lakes 

Wilderness Area. 

Refined modeling with a higher resolution meteorological grid was conducted for the Alpine Lakes 

Class I area. Table 5-2 shows the maximum and 98th percentile predicted extinction changes for 2003-

2005 based on the high resolution modeling. The predicted impacts on the worst 98th 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 

Δdv 

8th H Δdv 

98th percentile

Maximum 

Δdv 

8th H Δdv 

98th percentile 

Maximum 

Δdv 

8th H Δdv 

98th 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 Visibility Impacts in the Refined Modeling 

Class I Area Maximum 

Δdv 

8th H Δdv 

98th percentile

Maximum 

Δdv 

8th H Δdv 

98th percentile 

Maximum 

Δdv 

8th H Δdv 

98th percentile

2003 2004 2005 

Alpine Lakes W. 0.640 0.200 0.845 0.379 0.535 0.307 
6-1

6.0 REFERENCES 

FLAG, 2000. Federal Land Manager' Air Quality Related Values Workgroup (FLAG). Phase I Report. U.S. 

Forest Service, National Park Service, 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 Model 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 Program. EPA-454/B-03-005, September 2003. 

Washington, Oregon, Idaho Protocol for the Application of the CALPUFF Modeling System Pursuant to the 

Best Available Retrofit Technology (BART) Regulation, November 2006