DEPARTMENT OF ENVIRONMENTAL QUALITY AIR QUALITY DIVISION

BART Application Analysis

AP

- 6044

August 4 , 2008

NAME OF FIRM: FMC Wyoming Corporation

NAME OF FACILITY: Granger Facility

FACILITY LOCATION: Section 36, T20N

, R111W

Sweetwater County, Wyomi ng

TYPE OF OPERATION: Sodium Products Plant

RESPONSIBLE OFFICIAL: Otto Schnauber

, Environmental Team Leader

MAILING ADDRESS: PO Box 872 Green River, WY 82935

TELEPHONE NUMBER: (307) 872

- 2257

REVIEWING ENGINEER S : Cole Anderson , Air Quality Engi neer Josh Nall, Air Quality Modeler

PURPOSE OF APPLICATION:

FMC Wyoming Corporation has submitted a Best Available Retrofit Technology (BART) application for the two 358.5 million BTU (MMBtu) coal

- fired boilers that operate at their Granger facility in Sweetwater County, Wyoming. Regulations governing the BART program have been established by the U.S. EPA in 40 CFR P art 51

- Appendix Y

. As stated in the

r egulations, a source is eligible for BART if it belongs within a g roup of stationary source

cate gories

, was not in operation prior to August 7, 1962, was in existence on August 7, 1977, and has the potential to emit 250 tons per year (tpy) or more of any visibility impairing air pollutant.

Fossil fuel boilers of more than 250 MMBtu per hour heat inp ut are listed as an eligible source

type . Potential emissions from both boilers at Granger ( installed in 1 976 ) for two visibility impairing air pollutant s, nitrogen oxides (NO

x ) and sulfur dioxide (SO 2 ), exceed 250 tpy and

t herefore th e units are eligible for BART

.

A BART

- eligible unit is “ subject ” to BART unless valid air quality dispersion modeling

demonstrates that the unit will not cause or contribute to visibility impairment in any Class I area. A single source that is responsible for a 0.5 deciv iew ( d v) change or more is considered to

“contribute” to visibility impairment at a Class I area , while a source that is responsible for a 1.0

dv change or more is considered to “cause” visibility impairment at a Class I area. A source is exempt from BART if the 98 th percentile daily change in visibility, as compared against natural background conditions, is less than 0.5 d v at all Class I areas for the entire multi

- year modeling period.FMC Wyoming Corporation

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Initial dispersion modeling (screening) conducted by the Division i ndicated that the Granger facility would be subject to BART , and therefore FMC Wyoming Corporation submitted a BART analysis to the Division on February 28, 2007

. Refined dispersion modeling, submitted in the BART analysis and described in detail below, i ndicates that the two boilers at Granger do not contribute to visibility impairment at any Class I area.

DESCRIPTION OF BART ELIGIBLE UNITS :

O perating parameters and potential emissions for the BART

- eligible units at the Granger facility

are summarized in the table below.

Unit Description Heat Input (MMBtu) SO 2

Emission

Limit

– lb/hr (tpy) N O

x Emission

Limit

– lb/hr (tpy) PM

Emission

Limit

– lb/hr (tpy)

UIN

- 14 #1 Coal

- Fired Boiler with FGD

scrubber and ESP control 358.5 71.70 (314) 250.95 (10 99) 35.85 (157)

UIN

- 15 #2 Coal

- Fired Boiler with FGD

scrubber and ESP control 358.5 71.70 (314) 250.95 (1099) 35.85 (157)

ESP = electrostatic precipitator FGD = flue gas desulfurization lb/hr = pounds per hour

MMBtu = million British thermal units

N O

x = nitrogen oxides PM = particulate matter

SO 2 = sulfur dioxide

tpy = tons per year

VISIBILITY IMPROVEMENT DETERMINATION :

The fifth of five factor s that must be considered for a BART determination analysis, as required by 40 CFR P art 51

- Appendix Y, is the degree of Class I area visibility improvement that results from the possible options for control technology. This factor was evaluated for the FMC Granger facility by using an EPA

- approved dispersion modeling system (CALPUFF) to predict the cha nge in Class I area visibility. The Division had previously determined that the FMC Granger facility was subject to BART based on the results of initial screening modeling that was conducted using current (baseline) emissions from the facility. The scree ning modeling, as well as m ore refined modeling conducted by the applicant

, is described in detail below.

Bridger Wilderness Area (WA) and Fitzpatrick WA are the two closest Class I areas to the FMC Granger facility, as shown in F igure 1 below. Bridger W A is located approximately 11 6 kilometers (km) northeast of FMC Granger, while Fitzpatrick WA is located approximately 1 43 km northeast of the facility.

Only those Class I areas most likely to be impacted by the Granger sources were modeled, as

determ ined by source/Class I area locations, distances to each Class I area, and professionalFMC Wyoming Corporation

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judgment considering meteorological and terrain factors. A reas greater than 300 km from Granger were excluded. All source

- Class I area distances from Granger to Bridg er WA and Fitzpatrick WA exceed 50 km and are less than 300 km, thus falling within the range of recommended CALPUFF application. If impacts are less than the BART threshold for the Class I areas modeled, it can be reasonably assumed that areas at a great er distance and in directions of less frequent plume transport will not experience significant impacts.

Figure 1FMC Wyoming Corporation

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SCREENING MODELING To determine if the FMC Granger facility would be subject to BART, the Division conducted

CALPUFF modeli ng using three years of meteorological data. These data, from 1995

- 1996 and 2001, consisted of surface and upper

- air observations and gridded output from the prognostic

MM5 model. Resolution of the MM5 data was 36

- km for all three of the modeled years. S ources input to the modeling included the potential emissions (current operation) from the two BART

eligible emission units at the Granger facility, the coal

- fired boilers UIN

- 14 and UIN

- 15

.

Results of the modeling showed that the 98 th percentile value for the change in visibility (delta deciview [Δdv]) was above 0.5 dv for Bridger Wilderness for the meteorological data from 1996. As defined in EPA’s final BART rule, a 98 th percentile 0.5 dv impact from a given source

indicates that the source contributes to visibility impairment, and therefore is subject to BART. The results of the screening modeling are shown in the table below.

Results of the Class I Area Screening Modeling

Class I Area Maximum

Modeled Value (Δdv) 98 th

Percentile Value (Δdv)

1995

Br idger WA 0.86 0.2 7 Fitzpatrick WA 0.26 0.12

1996 Bridger WA 1.7 2 0.70 Fitzpatrick WA 1.14 0.2 3

2001 Bridger WA 1.09 0.495 Fitzpatrick WA 0.27 0.19

Δdv = delta deciview

WA = wilderness area

REFINED MODELING

Because of the results of the Divisi on’s screening modeling, FMC was required to conduct a refined BART analysis that included CALPUFF visibility modeling for the two coal

- fired boilers at the facility. The modeling approach followed the requirements described in the Division’s

BART modelin g protocol, BART Air Modeling Protocol

- Individual Source Visibility Assessments for BART Control Analyses (WDEQ

- AQD, September 2006)

.

CALPUFF System

Predicted visibility impacts from the FMC Granger sources were determined with the EPA

CALPUFF modelin g system, which is the EPA

- preferred modeling system for long

- range transport. As described in the EPA Guideline on Air Quality Models (Appendix W of 40 CFR Part 51), long

- range transport is defined as modeling with source

- receptor distances greater than

50 km . Because all modeled areas are located more than 50 km from the sources in question, the CALPUFF system was appropriate for use.FMC Wyoming Corporation

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The CALPUFF modeling system consists of a meteorological data pre

- processor (CALMET), an air dispersion model (CALPUFF) , and post

- processor programs (POSTUTIL, CALSUM, CALPOST). The CALPUFF model was developed as a non

- steady

- state air quality modeling system for assessing the effects of time

- and space

- varying meteorological conditions on pollutant transport, transformat ion, and removal.

CALMET is a diagnostic wind model that develops hourly wind and temperature fields in a three

dimensional, gridded modeling domain. Meteorological inputs to CALMET can include surface and upper

- air observations from multiple meteorolog ical monitoring stations. Additionally, the CALMET model can utilize gridded analysis fields from various mesoscale models such as MM5 to better represent regional wind flows and complex terrain circulations. Associated two

dimensional fields such as mix ing height, land use, and surface roughness are included in the input to the CALMET model. The CALMET model allows the user to “weight” various terrain influence parameters in the vertical and horizontal directions by defining the radius of influence

for surface and upper

- air stations.

CALPUFF is a multi

- layer, Lagrangian puff dispersion model. CALPUFF can be driven by the

three

- dimensional wind fields developed by the CALMET model (refined mode), or data from a single surface and upper

- air station in a format consistent with the meteorological file used to drive steady

- state dispersion models. All far

- field modeling assessments described here were completed using the CALPUFF model in a refined mode.

CALSUM is a post

- processing program that can operat e on multiple CALPUFF output files to combine the results for further post

- processing. POSTUTIL is a post

- processing program that processes CALPUFF concentrations and wet/dry flux files. The POSTUTIL model operates on one or more output data files from C ALPUFF to sum, scale, and/or compute species derived from those that are modeled, and outputs selected species to a file for further post

- processing. CALPOST is a post

- processing program that can read the CALPUFF (or POSTUTIL or CALSUM) output files, and calculate parameters such as visibility impacts.

All of the refined CALPUFF modeling was conducted with the version of the CALPUFF system that was recognized as the EPA

- approved release at the time of the development of the Division’s modeling protocol. Version designations of the key programs are listed in the table below.

Key Programs in CALPUFF System
Program Version Level

CALMET 5.53a 040716

CALPUFF 5.711a 040716

CALPOST 5.51 030709

Meteorological Data Processing (CALMET)

As required by the Division’s modeling protocol, the CALMET model was used to construct the

initial three

- dimensional windfield using data from the Mesoscale Model (MM5). Surface and

upper

- air data were then used by CALMET to adjust the initial windfield, but because of the relative scarcity of observations in the modeling domain, the influence of the observations was limited. Because the MM5 data were afforded a high degree of influence on the CALMETFMC Wyoming Corporation

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windfields, the Division obtained MM5 data at 12

- km resolution for the mod eling domain that spanned the years 2001

- 2003. Surface, upper

- air, and precipitation data for the domain was incorporated into the CALMET windfield. Locations of the various observations are shown in the figure below. The Division provided the BART appli cants all raw meteorological inputs for

the CALMET model.

Default settings were used in the CALMET input files for most of the technical options. The following table lists the key user

- defined CALMET settings that were selected.FMC Wyoming Corporation

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Key User

- Defined CALMET Settings

Variable Description Value

PMAP Map projection LCC

DGRIDKM Grid spacing (km) 4

NZ Number of layers 10

ZFACE Cell face heights (m) 0, 20, 40, 100, 140, 320, 580, 1020, 1480, 2220, 3 4 00

RMIN2 Minimum distance for extrapol ation

- 1

IPROG Use gridded prognostic model output 14

RMAX 1 Maximum radius of influence (surface

layer, km) 30

RMAX 2 Maximum radius of influence (layers

aloft, km) 50

TERRAD Radius of influence for terrain (km) 15

R1 Relative weightin g of first guess wind field and observations (km) 5

R2 Relative weighting aloft (km) 25

CALPUFF Modeling Setup

To allow chemical transformations within CALPUFF with the recommended chemistry scheme (MESOPUFF II), the model required input of backgr ound ozone and ammonia. For ozone, hourly data collected from the following stations were used:

Rocky Mountain National Park, Colorado (NP)
Craters of the Moon National Monument, Idaho Highland, Utah Thunder Basin, Wyoming Yellowstone NP, Wyoming

Centenn ial, Wyoming Pinedale, Wyoming

For any hour that was missing ozone data from all stations, a default value of 44 parts per billion (ppb) was used by the model as a substitute. For ammonia, a domain

- wide background value of 2 ppb was used.

Discrete rec eptors for the Class I areas that were modeled (Bridger WA and Fitzpatrick WA) were provided by the Division.FMC Wyoming Corporation

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CALPUFF Inputs

– Baseline Conditions Baseline stack parameters and emissions input to CALPUFF for the two units that were eligible

for BART a

re shown in the tables below.

Stack Parameters

Source LCC

East (km) (1) LCC

North (km) (1) Base

Elevation (m) Stack

Height (m) Stack

Diameter (m) Exhaust Tempera ture (K) Exit

Velocity (m/s)

UIN

- 14

- 108.329

- 93.371 1938.8 45.72 1.98 352.6 20.6

UIN

- 15

- 108.317

- 93.385 1938.8 45.72 1.98 352.6 20.6

(1) C oordinates based on UTM for UIN

- 14: 591757 m, 4613883 m and for UIN

- 15: 591770 m, 4613884 m

K = Kelvin

km = kilometers

LCC = Lambert Conformal Conic

m = meters m/s = meters per second

Emission Rate s

Source SO 2

(lb/hr) SO 4

(lb/hr) NO

x

(lb/hr) PMF

(lb/hr)

UIN

- 14 71.7 3.2 250.95 35.85

UIN

- 15 71.7 3.2 250.95 35.85

Note: Sulfuric acid (H 2 SO 4 ) emissions modeled in CALPUFF as SO 4 [H 2 SO 4 * (96/98)] lb/hr = pounds per hour

NO

x = nitrogen oxides PMF = fine particulate

SO 2 = sulfur dioxide

SO 4 = sulfatesFMC Wyoming Corporation

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Visibility Post

- Processing (CALPOST) Setup

The changes in visibility were calculated using Method 6 within the CALPOST post

- processor. Method 6 requires input of monthly r elative humidity factors [f(RH)] for each Class I area. Monthly f(RH) factors that were used for Bridger WA and Fitzpatrick WA are shown in the table

below.

Relative Humidity Factors for CALPOST

Month Bridger WA

Fitzpatrick WA

January 2.50

February 2. 30

March 2.30

April 2.10

May 2.10

June 1.80

July 1.50

August 1.50

September 1.80

October 2.00

November 2.50

December 2.40

According to the final BART rule, n atural background conditions as a reference for determination of the Δdv change within CALPOST should be representative of the 20% best natural visibility days. EPA BART guidance provides the 20% best days deciview values for each Class I area on an annual basis, but does not provide species concentra tion data for the 20% best background

conditions.

S pecies concentrations corresponding to the 20% best days were calculated for each Class I area by scaling back the annual average concentrations given in Table 2

- 1 of the EPA document Guidance for Esti mating Natural Visibility Conditions Under the Regional Haze Rule. A separate scaling factor was derived for each Class I area such that, when multiplied by the g uidance table annual concentrations, the 20% best days dv value for that particular Class I ar ea would be calculated. The scaled aerosol concentrations were averaged for the Bridger WA and Fitzpatrick WA because of their geographical proximity and similar annual background visibility. The 20% best days aerosol concentrations that were used for each month are listed in the table below.FMC Wyoming Corporation

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Natural Background Aerosol Co ncentrations (μg/m 3 )

Aerosol Component Fitzpatrick WA

Bridger WA

Ammonium Sulfate 0 .045

Ammonium Nitrate 0 .038

Organic Carbon 0 .178

Elemental Carbon 0 .008

Soil 0 .189

Coarse Mass 1.136

Visibility Post

- Processing Results

The results of the visibility modeling for both units combined are shown in the table below. For each year modeled, the 98 th percentile result was less than 0.5 Δdv at both Bridger WA and Fitzpatrick WA. Th ese result s show that the combined baseline emissions (curre nt operation) of

the two coal

- fired boilers at the FMC Granger facility do not contribute to Class I area visibility impairment. Based on this modeling, which was performed with higher resolution MM5 data than was used for the Division’s screening modelin g, the Division has determined that the facility is not subject to BART.

Results of the Class I Area Refined CALPUFF Modeling

Class I Area Maximum

Modeled

Value (Δdv) 98 th

Percentile

Value (Δdv)

2001 Bridger WA 0.573 0.327 Fitzpatrick WA 0.284 0.137

2002 Bridger WA 1.395 0.260 Fitzpatrick WA 0.609 0.201

2003 Bridger WA 0.749 0.390 Fitzpatrick WA 0.375 0.170FMC Wyoming Corporation

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C ONCLUSION S :

A refined CALPUFF visibility modeling analysis performed for the two BART

- eligible units at the FMC Wyoming Granger facility demonstrated that the predicted 98 th percentile impact s at the nearest Class I areas would be below 0.5 dv for all meteorological p eriods modeled. This modeling was conducted by the applicant, and verified by the Division, using higher

- resolution meteorological data as compared to the data used by the Division for the initial screening modeling that identified the facility as “subjec t ” to BART.

As stated in the final BART rule, sources with predicted visibility impacts less than 0.5 dv do not contribute to Class I area visibility impairment and are not “ subject ” to BART. Therefore, the

two BART

- eligible units at the FMC Wyoming G ranger facility are not “subject ” to BART and no additional controls are required to address visibility impacts in Class I areas

.