Appendix L 

Mississippi BART Determinations 
Appendix L – Mississippi BART Determinations 

• Introduction to Appendix L 

• Contribution Threshold 

• Tabular Summary of Appendix 

• L.1 – Entergy Mississippi Incorporated 

• L.2 – Georgia Pacific Corporation – Monticello 

• L.3 – Greenwood Utilities – Henderson 

• L.4 – Holcim (US) Incorporated 

• L.5 – International Paper Company – Vicksburg 

• L.6 – Mississippi Power Company 

• L.7 – Pursue Energy Corporation – Thomasville 

• L.8 – South Mississippi Electric Power Association 

• L.9 – Terra Mississippi Nitrogen, Inc. 

• L.10 – Chevron Pascagoula Refinery 

• L.11 – Mississippi Phosphates Corporation 

• L.12 – IMPROVE Equation Rationale 

• L.13 – BART Modeling Protocol 
Appendix L: Mississippi BART Determinations 

The 1999 regional haze rule includes the BART requirement, and directs States to include 

BART in their regional haze SIPs. On July 6, 2005, USEPA published a revised final 

rule, including Appendix Y to 40 CFR Part 51, the Guidelines for BART Determinations 

Under the Regional Haze Rule (hereinafter referred to as the “BART Guidelines”) that 

provides direction to states on determining which of these sources should be subject to 

BART, and how to determine BART for each source. 

A BART-eligible source is one which has the potential to emit 250 tons or more of a 

visibility-impairing air pollutant, was 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. Under the CAA, BART is required for any BART-eligible source that a State 

determines ‘‘emits any air pollutant which may reasonably be anticipated to cause or 

contribute to any impairment of visibility in any such area.’’ 

For those sources subject to BART, Section 169A(g)(7) of the CAA requires that States 

must consider the following factors in making BART determinations: (1) the costs of 

compliance, (2) the energy and non-air quality environmental impacts of compliance, (3) 

any existing pollution control technology in use at the source, (4) the remaining useful 

life of the source, and (5) the degree of improvement in visibility which may reasonably 

be anticipated to result from the use of such technology. 

Appendix L follows the BART determination process for all BART eligible sources in 

Mississippi. Although Mississippi does not have a Class I area, some of its sources affect 

Class I areas in neighboring states. The following table lists the BART eligible sources, 

the Class I area they affected, their visibility impact and the emissions modeled. As seen 

in this table Mississippi had fifteen BART-eligible sources, but only two, Chevron 

Refinery and Mississippi Phosphates had a visibility impact great enough to be BART 

subject. 

BART Eligible Source City Class I area SO2 tpy NOx tpy PM10 tpy

Holcim Artesia 148 Sipsey 5593 3390 95 0.34

Pursue Energy Thomasville 257 Breton 7761 0 0 0.17

Entergy MS - 

Baxter Wilson Vicksburg 320 Breton 0 0 10805 0.35

Entergy MS - 

Gerald Andrus Greenville 290 Caney Creek 0 0 6868 0.27

MS Power - Chevron Pascagoula 48 Breton 0 0 39 0.02

MS Power - Daniel Escatawpa 61 Breton 0 0 540 0.23

MS Power - Watson Gulfport 45 Breton 0 0 1834 0.42

International Paper Co - 

Vicksburg Redwood 328 Breton 1798 1270 1634 0.32

Georgia-Pacific Corp. Monticello 209 Breton 3932 3577 2412 0.33

SMEPA - Moselle Moselle 169 Breton n/a n/a n/a n/a

SMEPA - R D Morrow Purvis 138 Breton n/a n/a n/a n/a

Terra MS Nitrogen Inc Yazoo City 308 Sipsey 1 617 25 n/a

Greenwood Utilities Henderson 281 Sipsey 2030 260 254 0.22

Mississippi Phosphates Pascagoula 52 Breton 2409 22 196 0.81

Chevron Refinery Pascagoula 48 Breton 13815 6482 819 3.89

Dist. from Modeled Emissions: 24hr Average Maximum Actual 

Class I area 

Visibility Impact 

Delta Deciview
Also included in this appendix in section L.12 is the methodology and rationale behind 

the new IMPROVE equation which was developed to include the effects of coastal sea 

salt and site-specific Rayleigh scattering on light extinction. The BART modeling 

protocol used by VISTAS’ BART eligible sources to configure CALPUFF and its post 

processors can be found in section L.13. The tabular summary of Appendix L that 

includes the version(s) of the IMPROVE equation used, the resulting difference in 

visibility impact, whether a BART determination was required, the version of CALPUFF 

and its components used and who conducted the modeling is found at the end of 

Appendix L. 
Contribution Threshold 

Determining whether a source causes or contributes to visibility impairment is one step in 

the BART review process. The Guidelines for BART Determinations Under the Regional 

Haze Rule1

 state that “A single source that is responsible for a 1.0 deciview change or 

more should be considered to ‘cause’ visibility impairment.” The guideline document 

also states that “the appropriate threshold for determining whether a source ‘contributes 

to visibility impairment’ may reasonably differ across states,” but, “As a general matter, 

any threshold that you use for determining whether a source ‘contributes’ to visibility 

impairment should not be higher than 0.5 deciviews.” The rationale for these instructions 

is provided in the preamble to the BART guidance in the statement, “If ‘causing’ 

visibility impairment means causing a humanly perceptible change in visibility in 

virtually all situations (i.e. a 1.0 deciview change), then ‘contributing’ to visibility 

impairment must mean having some lesser impact on the conditions affecting visibility 

that need not rise to the level of human perception.”2 The guidance document itself also 

states that, “States remain free to use a threshold lower than 0.5 deciviews if they 

conclude that the location of a large number of BART-eligible sources within the State 

and in proximity to a Class I area justify this approach.” 

The EPA’s documents strive to set these thresholds in the context of the human 

perception of visibility change. As noted above, the EPA considers a 1.0-deciview 

change in visibility to be humanly perceptible “in virtually all situations.” Also, the 

preamble to the BART guidance3

 cites an analysis in an appendix of a NAPAP (National 

Acid Precipitation Assessment Program) report, which asserts that “changes in light 

extinction of 5 percent will evoke just noticeable changes in most landscapes.” 4 (A 5% 

change is approximately 0.5 dv.) But, as noted above, the preamble also states that 

perceptibility is not a prerequisite for choosing a contribution threshold. Putting all this 

together, it appears that “causing” visibility impairment means having a humanly 

perceptible impact (for which EPA considers the practical threshold to be 1.0 dv) while 

“contributing” to visibility impairment means having a smaller impact (for which EPA 

considers the threshold to be 0.5 dv or some smaller value) that may or may not be 

perceptible. 

The EPA states that a contribution threshold of less than 0.5 dv impact per source is 

appropriate when multiple sources contribute, in order to limit the combined effect of 

these sources. As an example, EPA makes the point that if there were 100 sources, each 

affecting visibility by 0.1 dv (presumably an imperceptible amount), their total impact 

would be 10 dv (which can be expected to be quite perceptible).5 The point remains that 

 

1

 40 CFR 51, Appendix Y, Section III.A.1 

2

 70 FR 39120. Footnote 31 

3

 70 FR 39119. Footnote 28 

4

 “The Quadratic Detection Model” by W. Malm. Appendix D in Acidic Deposition: State of 

Science and Technology, Report 24, Visibility: Existing and Historical Conditions -- Causes and 

Effects. National Acid Precipitation Assessment Program, Washington, DC. 1990. 

5

 70 FR 39121. 1st column 
multiple sources can cause a larger impact than a single one. For BART purposes, 

visibility impacts are calculated as 24-hr averages of 1-hr plume impacts, so if the plumes 

from the various sources each impact the point of interest at some time during a 24-hr 

period (not necessarily all at the same hour) then the 24-hr average will reflect their 

combined impact. 

Mississippi has a limited number (fifteen total) of sources that are BART eligible which 

are distributed throughout the state and impact different Class 1 areas. Therefore, MS 

DEQ has concluded that the EPA suggested contribution threshold of 0.5 dv is 

appropriate in this situation since there are a limited number of sources that impact the 

various Class I areas. Surrounding states with Class 1 areas have also adopted the 0.5 dv 

threshold. 
Tabular Summary of Appendix L

BART Source Mill/Plant City County State

Bart Category 

description

 BART 

category

Class I areas 

impacted

Dist. from 

Class I 

area (km)

IMPROV

E Eqn 

used

old v new 

@Max 

impact

% diff 

in 

IMPRO

BART 

Determination SO2 tpy NOx tpy PM10 tpy

CALMET 

ver/date

CALPOST 

ver/date

CALPUFF 

ver/date

POSTUTIL 

ver/date

V

D

Holcim Facility Artesia Lowndes MS

Portland cement plant 4

Sipsey Wilderness Area 148 old n/a n/a Eligible 5593 3390 95 5.726 5.6393 5.756 not used 

Pursue Energy Thomasville Thomasville Rankin MS Gas sulfur recovery 15

Breton National Wildlife Refuge 257 old n/a n/a Eligible 7761 0 0

5.724 

(04/14/06)

5.6393 

(02/02/06)

5.754 

(02/02/06)

1.52 

(02/06/06) 

Entergy MS Inc.

Baxter Wilson Vicksburg Warren MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 320 old n/a n/a Eligible 0 0 10805 5.726 5.6393 5.756 1.52 

Entergy MS Inc.

Gerald Andrus Greeneville Washington MS

Fossil fuel fired steam electric plant 1

Caney Creek Wilderness Area 290 old n/a n/a Eligible 0 0 6868 5.726 5.6393 5.756 1.52 

MS Power Chevron Pascagoula Jackson MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 48 new 0.03 to 0.02 33.33% Eligible 0 0 39 5.7 5.6393 5.754 1.52 

MS Power Daniel Escatawpa Jackson MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 61 new 0.29 to 0.23 21.69% Eligible 0 0 540 5.7 5.6393 5.754 1.52 

MS Power Watson Gulfport Harrison MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 45 new 0.52 to 0.42 19.23% Eligible 0 0 1834 5.7 5.6393 5.754 1.52 

International Paper Vicksburg Redwood Warren MS Kraft pulp mill 3

Breton National Wildlife Refuge 328 old n/a n/a Eligible 1798 1270 1634 5.723 5.6393 5.754 1.52 

Georgia-Pacific Monticello Lawrence MS Kraft pulp mill 3

Breton National Wildlife Refuge 209 old n/a n/a Eligible 3932 3577 2412 5.726 5.6393 5.756 not used 

South MS Electric Power Moselle Moselle Jones MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 169 old n/a n/a Eligible n/a n/a 84* n/a n/a n/a n/a 

South MS Electric Power R D Morrow Purvis Lamar MS

Fossil fuel fired steam electric plant 1

Breton National Wildlife Refuge 138 old n/a n/a Eligible n/a n/a 64* n/a n/a n/a n/a 

Terra MS Nitrogen Inc Yazoo City Yazoo MS

Fossil fuel fired steam electric plant 1

Sipsey Wilderness Area 308 old n/a n/a Eligible 1* 617* 25* n/a n/a n/a n/a 

Greenwood Utilities Henderson Greenwood Henderson MS

Fossil fuel fired steam electric plant 1

Sipsey Wilderness Area 281 old n/a n/a Eligible 2030 260 254 5.723 5.6393 5.754 1.52 

Mississippi Phosphates Pascagoula Jackson MS

Chemical process plant 21

Breton National Wildlife Refuge 52 old n/a n/a Subject 2409 22 196

5.724 

(04/14/06)

5.6393 

(02/02/06)

5.756 

(07/25/06)

1.52 

(04/12/06) 

Chevron Pascagoula Jackson MS Petroleum Refinery 11

Breton National Wildlife Refuge 48 old n/a n/a Subject 13815 6482 819 5.726 5.6393 5.756 1.52 

* - Represent potential emissions of BART eligible units.

Models used in BART modeling

Modeled Emissions: 24hr 

Average Maximum Actual