Prepared for : Prepared by: International Paper AECOM Mansfield, LA Mill Chelmsford, MA
604 85388 March 2016 

### Environment



# Mansfield Mill DeSoto Parish, Louisiana
1

- hour SO 2 

# Modeling ReportPrepared for : Prepared by: International Paper AECOM Mansfield, LA Mill Chelmsford, MA
604 85388 March 2016 

### Environment



# Mansfield Mill DeSoto Parish

, Louisiana
1

- hour SO 2 

# Modeling Report

_________________________________
Prepared By : Brian Stormwind

_________________________________
Reviewed By : Jeffrey ConnorsAECOM Mansfield Mill SO 2 Modeling Report Environment

March 2016 i



# Contents

1.0 Introduction

................................ ................................ ................................ .................... 1

- 1

1.1 Executive Summary

................................ ................................ ................................ ............. 1

- 1

1.2 Background

................................ ................................ ................................ .......................... 1

- 1

1.3 Overview of Analysis

................................ ................................ ................................ ........... 1

- 2

1.4 Facility Description and Location

................................ ................................ ......................... 1

- 3



### 2.0 Model Application and Options

................................ ................................ .................... 2

- 1

2.1 Source Data

................................ ................................ ................................ ......................... 2

- 1

2.1.1 Mansfield Mill

................................ ................................ ................................ ........ 2

- 1

2.1.2 Dolet Hills Power Station

................................ ................................ ...................... 2

- 2

2.2 Receptor Grid

................................ ................................ ................................ ....................... 2

- 5

2.3 Dis persion Environment

................................ ................................ ................................ ...... 2

- 5

2.4 Meteorological Data for Modeling

................................ ................................ ....................... 2

- 6

2.5 Background Monitoring Data

................................ ................................ ............................... 2

- 8



### 3.0 Modeling Results

................................ ................................ ................................ ........... 3

- 1

4.0 References

................................ ................................ ................................ ..................... 4

- 1



# List of Appendices

Appendix A EPA's Technical Support Document

Appendix B Modeling Protocol Submitted to LDEQ

Appendix C Modeling Archive CDAECOM Mansfield Mill SO 2 Modeling Report Environment

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# List of Tables

Table 2

- 1 S tack Parameters and Emission Rates

– Mansfield Mill

................................ .................. 2

- 4

Table 2

- 2 S tack Parameters and Emission Rates

– Dolet Hill Main Stack

................................ ....... 2

- 5

Table 2

- 3 Shreveport Monitor SO 2 Design Concentrations (2013

- 2015)

................................ ......... 2

- 9

Table 2

- 4 Shreveport Monitor Season and Hour of Day Background Concentrations (2013

- 2015) 2

- 9

Table 3

- 1 1

- hour SO 2 NAAQS Analysis Resul ts

- Concentrations ( μ g/m 3 )

................................ ...... 3

- 2

Table 3

- 2 Mansfield Mill Contribution to Modeled NAAQS Exceedances ( μ g/m 3 )

........................... 3

- 2



# List of Figures

Figure 1

- 1 Location of the Mansfield Mill

................................ ................................ ............................. 1

- 3

Figure 2

- 1 Mansfield Mill Sources and Buildings

................................ ................................ ................ 2

- 3

Figu re 2

- 2 AERMOD Receptor Grid

................................ ................................ ................................ .... 2

- 7

Figure 2

- 3 Location of SO 2 Monitor

................................ ................................ ................................ ... 2

- 10

Figure 2

- 4 Shreveport Wind Rose (2012

- 2014)

................................ ................................ ................ 2

- 11

Figure 3

- 1 Mansfield Mill Alone Modeling Results (excludes Ambient Background)

........................ 3

- 3

Figure 3

- 2 Receptor Locations of Modeled NAAQS Excee dances

................................ .................... 3

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# 1.0 Introducti on

1.1 Executive Summary

This document summarizes the results of sulfur dioxide ( SO 2 ) air quality modeling analysis for the International Paper (IP) Mansfield M ill (Mansfield Mill or the Mill) located in D e S oto Parish, LA. Th is modeling analysis was developed to address questions, uncertainties and data gaps lead ing to United States Environmental Protection Agency’s ( EPA ) precautionary decision to propose (81 FR 10563) a large geographical area surrounding both the Dolet Hills P ower S tation (Dolet Hills) and IP Mansfield
M ill as nonattainment with 1

- hr SO 2 National Ambient Air Quality Standards (NAAQS). This analysis considers emissions from both IP and Dolet Hills and pro vides gap filling information to a llow a n informed SO 2 designation decision for De S oto Parish.

This analysis shows:

 Emissions from the IP Mansfield M ill do not cause or significantly contribute ( no more than 0.40% of the total concentration ) to any modeled exceedances of the SO 2 NAAQS.

 The highest offsite impacts attributed to IP Mansfield Mill sources is 1 38  g/m 3

, comfortably (30%) below the NAAQS (196 .5  g/m 3 )

.

 Offsite impacts attributed to Mansfield Mill sources are highest within 1

- 2 km of the mill property boundary. Accordingl y, offsite concentrations decrease with increasing distance from the mill. At 5

- 8 k ilo m eters south

- south west (in the direction on Dolet Hills) , offsite impacts from Mansfield Mill sources are reduced to levels close to ambient background
levels

.

 IP Mansf ield Mill and Dolet Hill s are located a pproximately 14 km apart. As such, IP’s
emissions have no significant effect on ambient concentrations near the Dolet Hill s site.

 The highest modeled “combined” impact considering emissions from Dolet Hills, IP Man sfield
Mill and background levels is 208  g/m 3

. The Mansfield Mill is conservatively predicted to account for 0.2 3  g/m 3 (less than 0.5 0 %) of this combined impact.

 Based on these modeling results, t he IP Mansfield Mill should be specifically excluded from and remain outside any SO 2 nonattainment area boundary that may result from this designation process.

1.2 Background

On February 11, 2016, the EPA Region 6 issued a letter to the Honorable John Bel Edwards, Governor of Louisiana

, providing notice that EPA d isagreed with Louisiana’s SO 2 designation
recommend ation for the area surrounding Dolet Hills Power Station in DeSoto Parish. In short, EPA provided notice of its intention to designate a 193 square kilometer (~ 75 sq miles) area in DeSoto
Parish includin g the Dolet Hills P ower S tation and IP ’s Mansfield M ill, a s nonattainment with the 1

- hour SO 2 NAAQS. Shortly thereafter, n otice of this proposed designation action was published in the Federal Register (81FR 10563, 3/1/16) along with the opening of a 30

- da y public comment period

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The rational for EPA’s proposed action was outlined in a technical support document (TSD ; see Appendix A ). According to the technical support document, EPA ‘s decisions were based solely on air quality modeling of emissions from Dolet Hills prepared by the Sierra Club and subsequently amended by LADEQ. I P Mansfield Mill ’s emissions were not included in this or any subsequent modeling evaluations. The work in this document expands the previous modeling effort by LDEQ/Sierra Club to includ e Mansfield Mill sources , and amends the analysis as detailed in subsequent sections.

. The modeling methodology used in this analysis was originally outlined in the letter modeling protocol submitted to LDEQ on March 8, 2016 (provided in Appen dix B).

1.3 Overview of Analysis

As described above, modeling in this report w as conducted in a manner consistent with the LDEQ/Sierra Club analyses with the following exceptions to either refine the analysis or address potential deficiencies identified by EPA :

1. All modeling w as conducted using AERMOD DEFAULT model options ( see Section 2 .0 )

.

2. Estimated a ctual stack exhaust flow rates/ exit velocities were used in addition to the actual hourly emissions (used in the Sierra Club/LDEQ modeling) for Dolet Hills Power Station ( see Section 2.1.2)

. The Sierra Club and LDEQ modeling had used a constant exit velocity based on full load operations.

3. B uilding downwash was incorporated for both Dolet Hills and the Mansfield Mill ( see Section
2. 0 )

. No building downwash was inc luded in the modeling performed by Sierra Club or LDEQ.

4. Meteorological data was re

- processed with the latest version of AERMET

, Version 15181 (formerly, data processed with the prior version of AERMET, Version 14134, was used ) ( see Section 2. 4 )

.

5. IP Mansfie ld Mill sources w ere included in the modeling using their allowable emission rates for all SO 2 sources except Power Boiler #1 and #2 which were modeled using representative maximum hourly emission rates ( see Section 2.1.1).

6. The modeling w as conducted using one comprehensive receptor grid encompassing the area surrounding both facilities ( see Section 2. 2 )

.

7. Ambient background concentrations w ere updated based on 2013

- 2015 data for the Shreveport Monitor. 2011

- 2013 was used as part of the TSD, however that d ata only represented 2013 as the monitor was not in operation in 2011 and 2012. For this analysis,

r ather than conservatively adding the modeled design concentration with the monitored design concentration for this analysis, as a refinement, the ambient b ackground w as combined with modeled concentrations on a seasonal hour

- of

- day basis in accordance with EPA guidance in their March 1, 2011 clarification memo 1 and as outlined in EPA’s SO 2 Modeling Technical Analysis Document (TAD) 2 ( see Section 2.6)

.

Furth er details on these items and the modeling approach i s provided in Section 2 of this report

. A CD that contains all model input and output files is provided in Appendix C.

1 http://www.epa.gov/ttn/scram/guidance/clarification/Additional_Clarifications_AppendixW_Hourly

- NO2

- NAAQS_FINAL_03

- 01

- 2011.pdf

2 Available at: https://www3.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdfAECOM Mansfield Mill SO 2 Modeling Report Environment

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1.4 Facility Description and Location

IP 's Mansfield Mill is located in a rural area on the northeast side of Mansfield, LA, in the northern portion of DeSoto Parish. The facility is a containerboard mill whose sources of SO 2 emissions include: power boilers that burn a combination of either tire-derived fuel (TDF), gas, bark, and/or oil, two recovery furnaces, a lime kiln, an incinerator

, a gas turbine, and t wo smelt dissolving tanks. Additional details regarding these sources and their inclusion in the modeling is provided in Section
2.1.2. The facility location is shown in Figure 1-1.

Figure 1-1 Location of the Mansfield Mill



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# 2.0 Model Application and Options

Consistent with the Sierra Club and LDEQ modeling, AERMOD (Version 15181) was used for the analysis. AERMOD is the EPA guideline model for short-range transport and has the ability to account for the source types and dispersion environment located at, and surrounding, the Mansfield Mill and Dolet Hills. AERMOD (USEPA, 2004a) is appropriate for use in many different types of dispersion environments including sources subject to building downwash and sources located in flat or
elevated terrain.

For this application, AERMOD was applied using all regulatory default options and the modeling procedures were consistent with applicable guidance, including the February 2016 “SO 2 NAAQS Designations Modeling Technical Assistance Document” (TAD) issued by EPA . The current version of the TAD references other EPA modeling guidance documents, including the following clarification memos (1) the August 23, 2010 “ Applicability of Appendix W Modeling Guidance for the 1-hour SO 2 NAAQS ” and (2) the March 1, 2011 “ Additional Clarification Regarding Application W Modeling Guidance for the 1-hour NO 2 National Ambient Air Quality Standard ” (hereafter referred t o as the

“ Clarification M emo”). In the March 1, 2011 clarification memo, EPA declares that the memo applies equally to the 1-hour SO 2 NAAQS even though it was prepared primarily for the 1-hour NO 2 NAAQS.

Based on EPA guidance provided in the TAD, all stacks were modeled with their actual physical stack height. In addition, the EPA’s Building Profile Input Program (BPIP-Version 04274) version that is appropriate for use with PRIME algorithms in AERMOD were used to incorporate downwash effects in the model for all stacks at Dolet Hills and the Mansfield Mill included in the analysis. Figure 2-1 shows the Mansfield Mill stacks and building included in the BPIP analysis. The BPIP input and output files are provided in the modeling archive in Appendix C.

2.1 So urce Data

2.1.1 Mansfield Mill

The Mansfield Mill primary SO 2 sources and buildings are shown in Figure 2-1. Source stack parameters and emissions are summarized in Table 2- 1.

The EPA TAD allows for use of actual hourly emissions as well as the very conservative approach of using maximum potential emission rates. A hybrid approach was used for the Mansfield Mill sources by using a conservative constant, representative maximum hourly SO 2 emission rate for Power Boilers No. 1 and 2 while all other Mill sources were modeled with maximum permitted emission rates.

Maximum actual SO 2 emission factors from the Nos. 1 and 2 Power Boilers were developed from a statistical evaluation of the hourly SO 2 CEM data (lb/MMBtu) for the period 2012-2014. The resulting maximum actual SO 2 emission factors are 0.425 lb/MMBtu (No. 1 Power Boiler) and 0.480 lb/MMBtu (No. 2 Power Boiler). These maximum actual emission factors were multiplied by the maximum heat input of each boiler (760 MMBtu/hr) to obtain the maximum actual SO 2 emission rate for the Nos. 1 and 2 Power Boilers (323.3 and 364.9 lbs/hr, respectively). These rates were then conservatively modeled for every hour for the period 2012-2014.

Comparison of the maximum actual hourly SO 2 emission rate to the actual hourly SO 2 emission rate shows that 99.5% of all actual hourly SO 2 rates are below the maximum actual rates modeled. Review of the remaining 0.5% of the actual rates determined to be above the modeled maximum actual rates shows these periods to be atypical operation s.AECOM Mansfield Mill SO 2 Modeling Report Environment

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Given the low fraction of time and intermittent nature of the actual emission rate s are above the two proposed maximum actual emission rates, use of these max imum actual SO 2 rates will provide a conservative depiction of the modeled concentrations associated with the 1

- h ou r SO 2 NAAQS given its percentile basis ( 99th percentile )

.

Exhaust parameters were taken from the facility Title V operating permit and were verified by the
Mansfield Mill.

2.1.2 Dolet Hills Power Station

As discussed in EPA’s TSD, the Sierra Club and LDEQ modeling of Dolet Hills was conducted with 3 years, 2012

- 2014, of actual emission data coupled with constant exit flowrate/velocity and temperature based on 100% load (the latter was indicated by EPA to be a shortcoming of the analysis ).

In order to address EPA’s comment, hourly exit flowrate/velocity data were developed for this application to refine the analysis. Direct measurements of actual hourly exit flowrate/velocity and temperature for Dolet Hills were not available. However , heat input, MMBtu/hr, was available for Dolet Hills from the EPA Air Markets Program Data 3 . Concurrent with the hourly emission rates, hourly values of exit velocity for the Dolet Hills stack were computed based on the product of the full load
exhaust f lowrate (assumed to be 84.78 ft/s according to the LDEQ and Sierra Club m odeling) and the ratio of the actual hourly heat input/maximum load heat input (7,600 MMBtu/hr). The full load exit temperature was not adjusted as significant variability in the tem perature as a function of load is not expected. The 84.78 ft/s full load exhaust flowrate is also fairly consistent with data available in the Tile V Permit renewal for the Dolet Hills available on LDEQ’s website (October 2013, Permit Activity
No. PER2010 0002). This Title V Permit renewal was also used as a reference to determine the maximum heat input at 7,600 MMBtu/hr to the unit.

The physical stack parameters for the Dolet Hills main stack and full load exhaust parameters are
summarized in Table 2

- 2.

3 https://ampd.epa.gov/ampd/AECOM Mansfield Mill SO 2 Modeling Report Environment

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Figure 2

- 1 Mansfield Mill Sources and BuildingsAECOM Mansfield Mill SO 2 Modeling Report Environment

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Table 2

- 1 S tack Parameters and Emission Rates

– Mansfield Mill

Parameter Source

No. 1 Power Boiler No. 2 Pow er

Boiler Lime Kiln No. 1 Recovery Boiler No. 2

Recovery Boiler No. 1 Smelt

Dissolving Tank No. 2 Smelt

Dissolving Tank Gas

Turbine/HR SG Stack HVLC/LVHC

Incinerator

Stack ID 01

- 78 02

- 78 03

- 78 04

- 78 05

- 78 06

- 78 07

- 78 13

- 93 57

- 99 Base Elevation ( ft ) 179.8 179.1 179.1 179.1 179.1 179.1 179.1 179.5 179.1 Stack Height (ft ) 263.0 263.0 120.0 263.0 263.0 261.0 261.0 113.0 100.0 Stack Diameter ( ft ) 9.5 9.5 8.0 9.9 9.9 7.0 7.0 11.7 2.5 Exhaust Velocity (ft/sec) 101.5 101.5 23.4 96.2 96.2 30.9 30.9 47.8 33.3 Exhaust Temperature ( ° F ) 426.0 426.0 192.0 400.0 400.0 160.1 160.1 272.0 130.0

SO 2 Emission Rate (lb/hr) 323.2 364.9 1.20 217.64 217.64 1.35 1.35 <0.001 10.93AECOM Mansfield Mill SO 2 Modeling Report Environment

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Table 2

- 2 S tack Parameters and Emission Rates

– Dolet H ill Main Stack

Parameter Main Boiler Stack Base Elevation ( ft ) 244.2
Stack Height (ft ) 525.0
Stack Diameter ( ft ) 25.0
Exhaust Velocity (ft/sec) Varied hourly
Exhaust Temperature ( ° F ) 163.0

SO 2 Emission Rate (lb/hr) Varied hourly

2.2 Receptor Grid

The modeling was conducted using one comprehensive receptor grid encompassing the area surrounding Dolet Hills and the Mansfield Mill . The grid extend s out a minimum of 20 kilometers in all directions from each facility. The grid w as based on the f ollowing specifications:

 25

- meter spacing around each facility’s ambient air boundary;

 Beyond the ambient air boundary from each facility, 100

- meter spaced receptors w ere used
out to 3

- 5 km depending on the direction from the facilities;

 Beyond the 100

- met er spaced receptors a 250

- meter spaced grid we re used out to an additional 4

- 8 kilometers from each facility depending on the direction;

 Beyond the 250

- meter spaced receptors a 500

- meter spaced grid will be used out to an additional 5 kilometers; and

 B eyond the 500

- meter spaced receptors a 250

- meter spaced grid will be used out to an additional 10 kilometers.

The receptor grid is shown in Figure 2

- 2

.

The extent of this grid wa s sufficient to capture the maximum modeled impacts from each facility as

we ll as the combined impacts from both facilities

.

The receptor grid was based on Universal Transverse Mercator (UTM) coordinates referenced to NAD
83 datum and in zone 1 7 . AERMAP (version 11103), the AERMOD terrain preprocessor program,

w as used to calcula te terrain elevations and critical hill heights for the modeled receptors (NAD83
datum and zone 1 8 ) using National Elevation Data (NED). The NED dataset w as be downloaded from the USGS website (http://viewer.nationalmap.gov/viewer/) and consist ed of 1 arc second (~ 30 m resolution) NED. As per the AERMAP User’s Guide (USEPA, 2004 c ), the domain w as sufficient to ensure all significant nodes are included such that all terrain features exceed ing a 10% elevation slope from any given receptor

, are considered.

2.3 D ispersion Environment

Consistent with modeling performed by the Sierra Club and LDEQ, and EPA’s findings in the TSD, AERMOD was applied in rural mode given the predominantly rural land use of the study area.AECOM Mansfield Mill SO 2 Modeling Report Environment

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2.4 M eteorological Data for Modeling

The same three years of meteorological data used by Sierra Club and LDEQ was used in this application of AERMOD; 2012

- 2014 data from Shreveport, LA. The data were reprocessed with the latest version of EPA’s AERMET ( USEPA, 2004 b), version 15181 (the data were formerly p rocessed with version 14134) and AERMINUTE, version 15272. We do note that a comparison of both data sets indicated that there were no differences in the meteorological data processed with either version
of AERMET.AECOM Mansfield Mill SO 2 Modeling Report Environment

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Figure 2

- 2 AERMOD Receptor GridAECOM Mansfield Mill SO 2 Modeling Report Environment

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2.5 Background Monitoring Data

Ambient air quality data are used to represent the contribution of non

- modeled sources to the total ambient air pollutant concentrations for the NAAQS analysis

.

The Sierra Club and LD EQ analysis utilized monitored data from the Caddo Parish monitor in Shreveport, approximately 40 kilometers north of the Mansfield Mill ( see Figure 2

- 3 ). While EPA
states in the TAD that the Shreveport monitor has “the lowest measured background concentr ation in the state”, the Shreveport monitor is the most representative monitor available for the analysis , if not
conservative

.

The Mansfield Mill and Dolet Hills facilities are surrounded by rural land use generally consisting of agricultural and undevel oped forested and grassland areas, whereas the Shreveport monitor is in a more urban/developed area consisting of commercial and compact residential land uses. A three

year (2012

- 2014) wind rose of the Shreveport met data (see Figure 2

- 4 ) indicates winds in the region are predominantly from the south

. Winds blowing from the south would tend to transport SO 2 emissions from both the power station and mill toward the Shreveport monitor and t herefore, this
monitor may be influenced to some degree from the emi ssions from power station and mill.
T herefore the use of this monitor may result in some double counting of emissions in the analysis. For these reasons, the Shreveport monitor should be conservative to represent background in the vicinity of the Mansfi eld Mill and Dolet Hills.

EPA ’s recommends a tiered approach for adding monitored background concentrations (representing

non

- modeled sources) in the NAAQS analysis in the Clarification Memo . The first tier approach is conservatively based on adding the m onitored design value (3

- year average 99 th percentile daily 1

- hour maximum concentration) to the modeled design value. The second tier uses a temporally varying approach, based on combining the monitored concentrations

, by hour of day and season

, with
the hourly modeling results . The total hourly modeled plus monitored concentrations are then used to
determin e the design concentration for comparison to the NAAQS

. These computations are all done
within AERMOD.

Ther e fore , rather than conservatively addin g the modeled design concentration with the monitored design concentration for this analysis, the second tier refinement was used where the ambient background concentration was combined with modeled concentrations on a seasonal hour

- of

- day
basis in accorda nce with EPA guidance in the C larification M emo and as outlined in the TAD. Note that f or this application, the a mbient background concentrations were updated based on 2013

- 2015 data for the Shreveport m onitor. Data from 2011

- 2013 w ere reported to be use d by Sierra Club and LDEQ as discussed in the TSD, however it appears that data only represented 2013 as the monitor

was no t in operation in 2011 and 2012. Therefore, the more recent data were used.

Table 2

- 3 shows the three year design concentrations for the Shreveport monitor

.

Table 2

- 4 shows the season and hour of day ambient background concentrations used for the modeling. A spreadsheet with the season and hour of day background calculations is pr ovided with the modeling archive in Appendix C

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Table 2

- 3 Shreveport Monitor SO 2 Design Concentrations (2013

- 2015)

Monitor Year Annual Data Capture 99 th Percentile Concentration (ppb) Design

Concentration

(3

- year average)

hours % ppb μg/m 3

Shreveport Monitor 2013 8588 98% 12

12 32. 3

2014 8589 98% 14

2015 8367 96% 11

Table 2

- 4 Shreveport Monitor Season and Hour of Day Background Concentrations (2013

- 2015)

Hour Season (ppb)

Wint er Spring Summer Fall

1 2.5 2.6 2.6 2.1

2 2.8 2.6 2.9 1.9

3 3.0 2.5 2.6 2.1

4 2.9 2.4 2.7 2.4

5 2.9 2.4 2.6 2.1

6 2.7 2.5 2.6 2.0

7 2.3 2.7 2.8 1.9

8 2.4 3.2 5.2 2.7

9 3.2 3.8 9.3 3.8

10 2.7 4.4 9.5 5.3

11 5.1 4.3 6.9 7.0

12 6.1 4.5 6.2 4.6

13 6.4 4.1 4.7 3.7

14 5.1 3.7 3.8 4.2

15 4.2 3.3 3.7 3.1

16 4.1 3.0 4.5 3.8

17 3.7 3.2 3.7 3.0

18 3.1 3.1 3.6 3.4

19 3.1 2.9 4.2 3.3

20 2.8 2.7 3.5 2.7

21 3.7 2.7 3.1 2.1

22 3.2 3.1 2.7 2.0

23 3.9 3.5 3.8 2.1

24 3.1 2.9 2.8 2.3AECOM Mansfield Mill SO 2 Modeling Report Environment

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Figure 2-3 Location of SO 2 Monitor



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Figure 2

- 4 Shreveport Wind Rose (2012

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# 3.0 Modeling Results

AERMOD was applied for the 3

- year meteorological data set to determine the combined 1

- hour SO 2 modeled concentrations for the Mansfield Mill sources and the Dolet Hills main stack. As noted in Section 2. 5 , AERMOD was also applied with season/hour

- of

- day ambient background concentrations to represent non

- modeled sources in th e NAAQS analysis . AERMOD computes the total design concentrations in the form of the NAAQS which is the highest 3

- year average 99 th percentile of the daily 1

- hour maximum concentrations.

Table 3

- 1 summarizes the AERMOD modeled concentrations as well as source culpability. The following summar izes of the r esults in Table 3

- 1:

 O verall highest concentration due to all sources plus monitored background is 207.57 μ g/m 3

. This maximum total modeled concentration exceeds the NAAQS (196 .5 μ g/m 3 ) and is primaril y due t o Dolet Hill emissions . The Mansfield Mill sources contribution to this total

conce n tration is only 0.23 μ g/m 3 ( ~0.1 0 % of the total )

.

 Maximum modeled concentration due to all soucres (plus monitored background) where Mansfield Mill sources have a significant impact ( ≥ 7.9 μ g/m 3 ) is 152.21 μ g/m 3 ; the contribution from the Mansfield Mill sources is 8.50 μ g/m 3 (5.6% of the total )

.

 Highest concentration (plus background) due to Mansfield Mill sources alone is 13 7.59 μ g/m 3

. Figure 3

- 1 presents an isopleth of the modeling results for the Mansfield Mill sources alone

. As shown in Figure 3

- 1 , the highest concentrations associated with the Mansfield M ill sources are at the facility boundary , are below the NAQQS, and they drop off significantly with
distance from the Mill

. F igure 3

- 1 also shows that at 5

- 8 kilometers from the Mill center , the modeled concentrations (attributable to the Mill alone) drop to nearly the same concentration levels of the ambient background

. This distance is well short of the Dolet Hills Power Stat ion also shown in Figure 3

- 1.

In addition, there are a number of other instances and receptor locations where the NAAQS was exceeded. The location of these receptors is shown in Figure 3

- 2 . A detailed summary of all modeled exceedances is provided in Tab le 3

- 2. This summary shows that the Mansfield Mill sources do not significantly contribute to any of the modeled exceedances. The maximum modeled contribution to any of the modeled exceedances due to the Mansfield Mill sources is 0.79 μ g/m 3 (

~ 0.4 0% of NA AQS)

. Figure 3

- 2 also shows how large the proposed NAA made by EPA is relative to the area of actual
modeled exceedances.

These results demonstrate that the Mansfield Mill does not contribute significantly to any of the
modeled exceedances which are due t o Dolet Hills. The modeling analysis also demonstrates that the Mansfield Mill itself does not cause any modeled exceedance of the NAAQs.AECOM Mansfield Mill SO 2 Modeling Report Environment

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Table 3

- 1 1

- hour S O 2 NAAQS Analysis Results

- Concentrations ( μ g/m 3 )

Case Total

Concentration (1) Contribution to Total

NAAQS SIL

Dolet Hills Mansfield

Mill Monitored

Background

Overall Maximum 207.57 189.50 0.23 17.85 196 7.9

Maximum where Mansfield Significant 152.21 132.29 8.50 11.42 196 7.9

Maximum due to Mans field Mill Alone 137.59

-- 115.70 2 1.88 196 7.9

1) 1

- hour SO 2 9 9 th percentile design concentration s

.

Table 3

- 2 Mansfield Mill Contribution to Modeled NAAQS Exceedances ( μ g/m 3 )

Receptor Maximum Design Concentr ation (with Background) Mansfield Mill Contribution to Maximum Design Concentration X (m) Y (m)

443400.00 3544350.00 207.57 0.23

443300.00 3544350.00 207.25 0.55

443000.00 3544450.00 205.42 0.36

443500.00 3544350.00 204.59 0.23

443200.00 3544350.00 204.32 0.67

442900.00 3544450.00 203.86 0.79

443100.00 3544450.00 202.45 0.36

443100.00 3544350.00 201.29 0.67

443600.00 3544350.00 201.20 0.23

443200.00 3544450.00 200.09 0.34

442800.00 3544450.00 199.35 0.79

442600.00 3544550.00 198.43 0.34

4430 00.00 3544350.00 198.40 0.79

442700.00 3544550.00 198.18 0.32

443300.00 3544450.00 197.67 0.34

443700.00 3544250.00 197.36 0.55

442800.00 3544550.00 197.31 0.47

442500.00 3544550.00 197.27 0.38

442900.00 3544550.00 197.05 0.36

443800.00 3544250.00 1 96.27 0.23

443700.00 3544350.00 196.20 0.18AECOM Mansfield Mill SO 2 Modeling Report Environment

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Figure 3

- 1 Mansfield Mill Alone Modeling Results ( excl udes Ambient Background)AECOM Mansfield Mill SO 2 Modeling Report Environment

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Figure 3

- 2 Receptor Locations of Modeled NAAQS Exceedances

*Receptor locations with modeled exceedances are shown in blue. EPA proposed NAA outlined in with bold blue lineAECOM Mansfield Mill SO 2 Modeling Report Environment

60432329 Mar ch 2016 4

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# 4.0 References

US EPA 1985. Guideline for the Determination of Good Engineering Practice Stack Height (Technic al Support Document for the Stack Height Regulations)

- Revised. EPA

- 450/4

- 80

- 023R, US EPA, Research Triangle Park, NC 27711.

US EPA 2004a. User’s Guide for the AMS/EPA Regulatory Model (AERMOD). EPA

- 454/B

- 03

- 001 (September 2004

– Addendum March 2011 ). Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

US EPA 2004b. User’s Guide for the AERMOD Meteorological Preprocessor (AERMET). (EPA

454/B

- 03

- 002, November 2004

– Addendum February 2011). Office of Air Quality Plannin g and Standards, Research Triangle Park, North Carolina.

US EPA 2004c. User’s Guide for the AERMOD Terrain Preprocessor (AERM AP ). (EPA

- 454/B

- 03

- 00 3

, October 2004

– Addendum March 2011 ). Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina.

US EPA 2011. Additional Clarification Regarding Application of Appendix W Modeling Guidance for the 1

- hour NO 2 NAAQS. (March 1, 2011). Office of Air Quality Planning and Standards, Research Triangle Park, North Carolina. Available at: http://www.epa.gov/ttn/scram/Additional_Clarifications_ AppendixW_Hourly

- NO2

- NAAQS_FINAL_03

- 01

- 2011.pdf

US EPA 2015. Docket ID No. EPA

– HQ

– OAR

– 2013

– 0711, August 10, 2015. Available at: http://www.epa.gov/oaqps001/sulfurdioxide/pdfs/so2_drr__final_081215.pdf

.AECOM Mansfield Mill SO 2 Modeling Report Environment

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# Appendix A

EPA's Technical Support
Document

### Technical Support Document
Louisiana

Area Designations for the 2010 SO 2 

### Primary National Ambient Air Quality Standard

Summary

Pursuant to section 107(d) of the Clean Air Act (CAA), the U.S. Environmental Protection Agency (EPA) must designate areas as either “u nclassifiable,” “attainment ,” or “nonattainment” for the 2010 one-hour sulfur dioxide (SO 2 

### ) primary national ambient air quality standard (NAAQS). The CAA defines a nonattainment area as one that does not meet the NAAQS or that
contributes to a violation in a ne arby area. An attainment area is defined as any area other than a nonattainment area that meets the NAAQS. Unclassi fiable areas are defined as those that cannot
be classified on the basis of available info rmation as meeting or not meeting the NAAQS.

Louisiana submitted updated recommendations on November 17, 2015, ahead of a July 2, 2016, deadline for the EPA to designate certain areas es tablished by the U.S. District Court for the
Northern District of California. This deadline is the first of three deadlines established by the court for the EPA to complete area designations for the 2010 SO 2 

### NAAQS. Table 1 below lists
Louisiana’s recommendations and identifies the coun ties or portions of coun ties in Louisiana that the EPA intends to designate by July 2, 2016 base d on an assessment and characterization of air quality through ambient air quality data, air di spersion modeling, other evidence and supporting information, or a combination of the above.

Table 1: Louisiana’s Recommended and EPA’s Intended Designations

Area Louisiana’s
Recommended
Area Definition Louisiana’s
Recommended

Designation EPA’s Intended Area
Definition EPA’s Intended Designation

DeSoto Parish,
Louisiana Within the
Southeast Quadrant of
DeSoto Parish Attainment Portions of Desoto Parish, Louisiana:

The area bounded by the following UTM Coordinates* (NAD 83 Datum, UTM Zone 15):

X Y 441287, 3541019 441287, 3562019 450500, 3562019 450500, 3541019

* Nonattainment area excludes portions of Red River Parish, Louisiana
that fall within this UTM-based boundary Nonattainment

### 2 Calcasieu Parish,
Louisiana Within
Calcasieu Parish
Borders Attainment Same as State’s Recommendation Unclassifiable



### Background

On June 3, 2010, the EPA revised the primary (health based) SO 2 

### NAAQS by establishing a new
one-hour standard at a level of 75 parts per billion (ppb) which is attained when the three-year average of the 99th percentile of one-hour da ily maximum concentrations does not exceed 75 ppb. This NAAQS was published in the Federal Re gister on June 22, 2010 (75 FR 35520) and is
codified at 40 CFR 50.17. The EPA determined this is the level necessary to protect public health with an adequate margin of safety, especially for children, the elderly and those with asthma. These groups are particularly susceptible to th e health effects associated with breathing SO 2 

### . The two prior primary standards of 140 ppb evaluate d over 24 hours, and 30 ppb evaluated over an entire year, codified at 40 CFR 50.4, remain applicable. 1 

### However, the EPA is not currently designating areas on the basis of ei ther of these two primary sta ndards. Similarly, the secondary
standard for SO 2, 

### set at 500 ppb evaluated over 3 hours has no t been revised, and the EPA is also not currently designating areas on the basis of th e secondary standard.

General Approach and Schedule

Section 107(d) of the Clean Air Ac t requires that, no later than one year after promulgation of a new or revised NAAQS, state governors must s ubmit their recommendations for designations and boundaries to EPA. Section 107(d) also require s the EPA to provide notification to states no less than 120 days prior to promulgating an initial area desi gnation that is a modification of a state’s recommendation. If a state does not submit designation recommendations, the EPA will promulgate the designations that it deems appropriate. If a state or tribe disagrees with the EPA’s intended designations, they are given an opportun ity within the 120-day period to demonstrate why any proposed modificati on is inappropriate.

On August 5, 2013, the EPA published a final rule establishing air quali ty designations for 29
areas in the United States for the 2010 SO 2 

### NAAQS, based on recorded air quality monitoring data from 2009 - 2011 showing violations of th e NAAQS (78 FR 47191). In that rulemaking, the EPA committed to address, in separate future actions, the designations for all other areas for which the Agency was not yet prepared to issue designations.

Following the initial August 5, 2013 designations, th ree lawsuits were file d against the EPA in different U.S. District Courts, alleging the ag ency had failed to perform a nondiscretionary duty under the CAA by not designating all portions of the country by the June 2013 deadline. In an

1 40 CFR 50.4(e) provides that the two prior primary NAAQ S will no longer apply to an area one year after its designation under the 2010 NAAQS, except that for areas designated nonattainment under the prior NAAQS as of August 22, 2010, and areas not meeting the requirements of a SIP Call under the prior NAAQS, the prior NAAQS will apply until that area submits and EPA approves a SIP providing for attainment of the 2010 NAAQS.

### 3 

### effort intended to resolve the litigation in one of those cases, plaintiffs Sierra Club and the
Natural Resources Defense Council and the EPA f iled a proposed consent decree with the U.S.
District Court for the Northern District of California. On March 2, 2015, the court entered the consent decree and issued an enforceable order for the EPA to complete the area designations according to the consent decree schedule.

According to the consent decree, the EPA mu st complete the remaining designations on a schedule that contains three spec ific deadlines. By no later than July 2, 2016 (16 months from the court’s order), the EPA must desi gnate two groups of areas: (1) areas that have newly monitored
violations of the 2010 SO 2 

### NAAQS and (2) areas that contain a ny stationary sources that had not been announced as of March 2, 2015 for retiremen t; and that according to the EPA’s Air Markets Database emitted in 2012 either (i) more than 16,000 tons of SO 2 

### or (ii) more than 2,600 tons of
SO 2 

### with an annual average emission rate of at least 0.45 pounds of SO 2 

### per one million British thermal units (lbs SO 2 

### /mmBTU). Specifically, a stationary source with a coal-fired unit that as of January 1, 2010 had a capacity of over 5 me gawatts and otherwise meets the emissions criteria, is excluded from the July 2, 2016 dead line if it had announced through a company public announcement, public utilities commission filing, c onsent decree, public le gal settlement, final state or federal permit filing, or other similar means of communication, by March 2, 2015, that it will cease burning coal at that unit.

The last two deadlines for completing re maining designations are December 31, 2017, and December 31, 2020. The EPA has separately promul gated requirements for states and other air agencies to provide additional monitoring or mode ling information on a timetable consistent with these designation deadlines. We expect this information to become available in time to help inform these subsequent designations. These requirements were promulgated on August 21, 2015 (80 FR 51052), in a rule known as the SO 2 

### Data Requirements Rule (DRR).

The EPA through a March 20, 2015 memorandum from Stephen D. Page, Director, U.S. EPA, Office of Air Quality Planning and Standards issued updated designati ons guidance, to Air Division Directors, U.S. EPA Regions I-X. This memorandum s upersedes earlier designation guidance for the 2010 SO 2 

### NAAQS, issued on March 24, 2011, a nd it identifies factors that the EPA intends to evaluate in determining wh ether areas are in vi olation of the 2010 SO 2 

### NAAQS. The guidance also contains the factors the EPA in tends to evaluate in determining the boundaries for all remaining areas in the country, consiste nt with the court’s or der and schedule. These factors include: 1) Air quality characterizati on via ambient monitoring or dispersion modeling results; 2) Emissions-related data; 3) Meteor ology; 4) Geography and topography; and 5) Jurisdictional boundaries. This guidance was su pplemented by two technical assistance
documents intended to assist states and other interested parties in their efforts to characterize air quality through air dispersion modeling or ambient air quality monitoring for sources that emit
SO 2 

### . Notably, the EPA released its most r ecent versions of documents titled, “SO 2 

### NAAQS Designations Modeling Technical Assist ance Document” (Modeling TAD) and “SO 2 

### NAAQS Designations Source-Oriented Monitoring Tech nical Assistance Document” (Monitoring TAD)
in December 2013.

### 4 

### Based on ambient air quality data collected between 2012 and 2014, no violations of the 2010
SO 2 

### NAAQS have been recorded in a ny undesignated part of the state. 2 

### However, there are 3 sources in the state meeting the emissions criteri a of the consent decree for which the EPA must complete designations by July 2, 2016. In th is draft technical support document, the EPA
discusses its review and technical analysis of Louisiana’s recomm endations for the areas that we must designate. The EPA also discusses a ny intended modifications from the state’s
recommendation based on all av ailable data before us.

The following are definitions of import ant terms used in this document: 1) 2010 SO 2 

### NAAQS – The primary NAAQS for SO 2 

### promulgated in 2010. This NAAQS is 75 ppb, based on the three-year average of th e 99th percentile of th e annual distribution of daily maximum one-hour averag e concentrations. See 40 CFR 50.17. 2) Design Value - a statistic computed according to the data handling procedures of the NAAQS (in 40 CFR part 50 Appendix T) that, by comparison to the level of the NAAQS,
indicates whether the area is violating the NAAQS. 3) Designated nonattainment area – an area which the EPA has determined has violated the
2010 SO 2 

### NAAQS or contributed to a violation in a n earby area. A nonattainment designation would reflect cons iderations of state recomm endations and all of the
information discussed in this document. The EPA’s decision would be based on all available information including the most rece nt 3 years of air quality monitoring data, available modeling analysis, and any other relevant information. 4) Designated unclassifiable area – an area wh ich the EPA cannot determine based on all
available information whethe r or not it meets the 2010 SO 2 

### NAAQS. 5) Designated unclassifiable/atta inment area – an area which the EPA has determined to
have sufficient evidence to find either is attaining or is like ly to be attaining the NAAQS.
The EPA’s decision would be based on all av ailable information including the most recent 3 years of air quality monitoring data , available modeling analysis, and any other
relevant information. 6) Modeled violation – a violation based on air dispersion modeling. 7) Recommended attainment area – an area a st ate or tribe has reco mmended that the EPA designate as attainment. 8) Recommended nonattainment area – an area a st ate or tribe has r ecommended that the EPA designate as nonattainment. 9) Recommended unclassifiable area – an area a state or tribe has recommended that the EPA designate as unclassifiable.

2 For designations based on ambient air quality monitoring data that violates the 2010 SO 2 NAAQS, the consent
decree directs the EPA to evaluate data collected betw een 2013 and 2015. Absent complete, quality assured and certified data for 2015, the analyses of applicable areas fo r the EPA’s intended designations will be informed by data
collected between 2012 and 2014. States with monitors that have recorded a violation of the 2010 SO 2 NAAQS during these years have the option of submitting complete, quality assured and certified da ta for calendar year 2015 by April 19, 2016 to the EPA for evaluation. If after our review, the ambient air quality data for the area indicates that no violation of the NAAQS occurred between 2013 and 2015, the consent decree does not obligate the EPA to complete the designation. Instead, we may designate the area and all other previously unde signated areas in the state on a schedule consistent with the prescribed timing of th e consent decree, i.e., by December 31, 2017, or December 31, 2020.

### 5 

### 10) Recommended unclassifiable/attainment area – an area a state or tr ibe has recommended that the EPA designate as unclassifiable/attainment. 11) Violating monitor – an ambien t air monitor meeting all me thods, quality assurance and siting criteria and requ irements whose valid design valu e exceeds 75 ppb, based on data analysis conducted in accordance wi th Appendix T of 40 CFR part 50.

### 6 

### Technical Analysis for the DeSoto Parish, Louisiana Area

Introduction

The Dolet Hills Power Station contains a sta tionary source that according to the EPA’s Air Markets Database, emitted in 2012 either more than 16,000 tons of SO 2 

### or more than 2,600 tons
of SO 2 

### and had an annual average emissi on rate of at least 0.45 pounds of SO 2 

### per one million British thermal units (lbs SO 2 

### /mmBTU). As of March 2, 2015, this stationary source has not met the specific requirements for being “announced fo r retirement.” Specifically, in 2012, the Dolet Hills Power Station (Dolet Hills) emitted 20,887 tons of SO 2 

### , and had an emissions rate of 0.80
lbs SO 2 

### /mmBTU. Pursuant to the March 2, 2015 cons ent decree, the EPA must designate the area surrounding the facility by July 2, 2016.

In its November 17, 2015 recommendation, Louisian a through its state environmental agency, the Louisiana Department of Environmental Quality (LDEQ), recommended that the area surrounding Dolet Hills, specifically the southeast quadran t of DeSoto Parish, be designated as
unclassifiable based on information included in a monitoring siting report. The report assessed and characterized air quality for the facility a nd other nearby sources. Our review and analysis indicated that this initial modeling intended to jus tify the siting of monitors did not follow either the monitoring TAD or modeling TAD in certa in respects and only provided normalized estimates of impacts rather than absolute results.

The EPA also received air modeling performed by Sierra Club (initially in September 2015 and updated in December 2015), asserting that the area around Dolet Hills experiences impacts in exceedance of the NAAQS. The state reviewed th is modeling, and subsequently performed its own revised modeling using the input parameters provided by Si erra Club. These assessments and characterization were performed using ai r dispersion modeling software, i.e., AERMOD, analyzing actual emissions. However, the state factored and used the cu rrently non-default beta option low wind speed modification (LOWWIND 3). This revised modeling using LOWWIND3 predicted peak concentrations slightly below the NAAQS. As a result, the state changed its
unclassifiable recommendation to attainment.

The EPA notes that the use of beta options , such as ADJ_U* and LOWWIND3, in AERMOD for any regulatory applications requi res adherence with Appendix W, Section 3.2.2. This is further explained in the EPA’s December 10, 2015 Memo randum titled, “Clarification on the Approval Process for Regulatory Application of the AERMOD Modeling System Beta Options.” Among other conditions, the use of beta options requires cons ultation with the appropriate EPA Regional Offices. Upon concurrence by the EPA’s Modeli ng Clearinghouse, EPA Regional Offices may approve the use of these beta options for regulatory applicatio ns as an alternative model. However, LDEQ performed air dispersion modeli ng intended to characterize air quality as a
result of SO 2 

### emissions from Dolet Hills without prio r consultation with and approval from an EPA Regional Office, and therefore has not met the applicable regulatory requirements contained in Appendix W, Section 3.2.2. As a result, the EPA does not believe that the air quality modeling results obtained from the use of these beta options can be used as a reliable indicator of
attainment status in the area around Dolet Hills until appropriate alternative model approval is

### 7 

### granted or these beta options are promulgate d as regulatory options in AERMOD through EPA rulemaking.

After careful review of the st ate’s assessment, supporting docume ntation, and all available data, the EPA does not agree with the state’s recomme ndation for the area, and intends to designate the area as non-attainment. Sp ecifically, the boundaries for ou r intended nonattainment area consist of the portions of DeSoto Parish bound by the following Universal Transverse Mercator (UTM) Coordinates (NAD 83 Datum, UTM Zone 15):

X Y

441287 3541019

441287 3562019

450500 3562019

450500 3541019

However, this intended nonattainment area exclud es portions of Red River Parish, Louisiana that fall within this UTM-based boundary. The modeli ng analyses indicates that there were no violating receptors in Red River Parish. Also, Figures 3 and 4 show that the impact area based on actual emissions did not extend past DeSoto Parish borders and, therefore, the defined
nonattainment area should be contained within.

Dolet Hills is located in northwestern Louisiana in the eastern portion of DeSoto Parish. As seen in Figure 1 below, the facility is located appr oximately 12.5 km directly east of the center of
Mansfield. Also included in the fi gure are major nearby emitters of SO 2 

### , and the DeSoto Parish boundary. EPA’s intended nonattainment designation ar ea is the area within DeSoto Parish that lies within a rectangular ar ea defined by UTM coordinates (See Figure 1 below). The nonattainment area excludes porti ons of Red River Parish, Louisi ana that fall within this UTMbased boundary.

### 8 

### Figure 1: SO 2 

### Nonattainment Area Designation for Dolet Hills

The discussion and analysis that follows below will reference the state’s use of the Modeling TAD in its revised modeling analysis, Sierra Club’s use of the Modeling TAD, the EPA’s assessment of the competing modeling in accord ance with the Modeling TAD, and the factors
for evaluation contained in the EPA’s Ma rch 20, 2015 guidance, as appropriate.

Detailed Assessment

Air Quality Data

There are no SO 2 

### air quality monitors in DeSoto Parish. There are no SO 2 

### air quality monitors in surrounding parishes that are repr esentative of the maximum or higher elevated levels of SO 2 

### around Dolet Hills.

### 9 

### Model Selection and Modeling Components

The EPA’s Modeling TAD notes that fo r area designations under the 2010 SO 2 

### NAAQS, the AERMOD modeling system should be used, unless us e of an alternative m odel can be justified. In some instances, the recommended model may be a model other than AERMOD, such as the BLP model for buoyant line sources. The AERM OD modeling system contains the following components:

- AERMOD: the dispersion model

- AERMAP: the terrain processor for AERMOD

- AERMET: the meteorological data processor for AERMOD

- BPIPPRIME: the building input processor

- AERMINUTE: a pre-processor to AERMET in corporating 1-minute automated surface observation system (ASOS) wind data

- AERSURFACE: the surface characte ristics processor for AERMET

- AERSCREEN: a screening version of AERMOD

The Sierra Club initial modeli ng (Sept. 2015) was conducted with the previous regulatory version of AERMOD (v14134). The state reviewed Sierra Club’s modeling and found that the inputs for the actual emissions were acceptable. The state reran the Sie rra Club modeling on the most recent version of AERMOD version 15181, using LOWWIND3 as the only altered model option. A discussion of the individual component s will be referenced in the corresponding discussion that follows as appropriate. Sie rra Club submitted updated modeling in December
2015 and used the most recent version of AE RMOD that was released in July 2015 (v15181).

Modeling Parameter: Rural or Urban Dispersion

The EPA’s recommended procedure for characterizing an area by prevalent land use is based on evaluating the dispersion environment within 3 km of the facility. According to the EPA’s modeling guidelines, urban dispersion coefficien ts are to be used in the dispersion modeling analysis if more than 50% of the area within a 3 km radius of the facility is classified as urban. Otherwise, the source is considered a rural source.

When performing the modeling for the area of anal ysis, the state agreed with Sierra Club’s analysis to use rural mode. Sierra Club us ed a Geographic Information System (GIS) to determine whether rural or urban dispersion co efficients applied. La nd use within a threekilometer radius circle surrounding the facili ty was considered. USEPA’s AERSURFACE v. 13016 was used to develop the meteorological data for the modeling analysis. This model was also used to evaluate surrounding land use w ithin 3 kilometers. Based on the output from the AERSURFACE, approximately 0.02% of surroundi ng land use around the modeled facility was of urban land use types including Type 21 – Low Intensity Residential, Type 22 – High Intensity Residential and Type 23 – Commer cial / Industrial / Transportati on. This is less than the 50% value considered appropriate for the use of urban dispersion coe fficients. Based on the AERSURFACE analysis, it was concluded that th e rural option would be used for the modeling summarized in this report.

### 10 

### Modeling Parameter: Area of Analysis (Receptor Grid)

The EPA believes that a reasonable first step toward characterizati on of air quality in the area surrounding Dolet Hills is to determine the extent of the area of analysis, i.e., receptor grid. Considerations presented in the Modeling TAD incl ude but are not limited to: the location of the
SO 2 

### emission sources or facilities considered for modeling; the ex tent of significant concentration gradients of nearby sources; and sufficient receptor coverage and density to adequately capture and resolve the model predicted maximum SO 2 

### concentrations.

For the DeSoto Parish area, the state recogni zed in its monitoring siting report 519 permitted facilities in the parish, with 10 Title V facilit ies, and only one that represented a major SO 2 

### emitter within 20 kilometers (km) in any direction of Dolet Hills. The state determined that this was the appropriate distance as described in the 2013 Monitoring TAD. In addition to Dolet Hills, one other major emitter of SO 2 

### is located within the area of analysis, International Paper Company (IP), is 14 km to the north of Dolet H ills. Neither Sierra Club nor the state’s modeling
included emissions from IP. The st ate asserted that emissions from this facility are represented by the background monitor data; however, the EPA does not agree that th e background monitor data used adequately represents any potential concentration gradients that may occur in the area
of concern from IP’s emissions. Based on th e modeling provided by Sierra Club and LDEQ, industry modeling for siting a monitor, one of th e higher areas with near modeled exceedances was to the south of the facility. When winds are out of the north and resulting in some of the highest values modeled around Dolet Hills, the IP source would be upwind and could contribute to concentration gradients around Dolet Hills and to the south of Dolet Hills. Coupling this with the proximity to Dolet Hills (approx. 14km), and size of IP emissions warrant consideration for explicit modeling, as suggested by Appendix W, because it is likely that the source causes concentration gradients that extend to area impacted by Dolet Hills with some of the higher
modeled values that are near the standard.

The grid receptor spacing by Sierra Club was re tained by the state in their modeling analysis along with all associated elevations and processing informati on that could potentially impact the area of analysis where maximum SO 2 

### concentrations are expected. The receptor network contained 21201 receptors (no graphical represen tation of the receptor grid was provided):

- A 100-meter Cartesian receptor grid centered on Dolet Hills and extending out 5 km.

- A 500-meter Cartesian receptor grid center ed on Dolet Hills and extending out 10
kilometers.

- A 1,000-meter Cartesian receptor grid centered on Dolet Hills and extending out 50 kilometers. 50 kilometers is the maximum distance accepted by USEPA for the use of the AERMOD dispersion model.

- A flagpole height of 1.5 meters wa s used for all these receptors.

This is a larger grid than we might normally recommend but this grid is acceptable for this analysis. Sierra Club modeling used a slightly elevated flagpole receptor height, but if this was
corrected to EPA’s recommended he ight we would expect only a slight change in the modeled

### 11 

### numbers and the area of exceedances and magnit ude of the values would be basically the equivalent and not change our proposed action. Figure 2 shows the area surroundi ng Dolet Hills originally provi ded in the state’s monitoring siting report provided to the EPA showing the location of all minor and major sources of SO 2 

### in DeSoto Parish. The state originally recommended that the area designated unclassifiable should be limited to the southeast quadrant of the parish bounded by United States Highway 84 on the north, United States Highway 171 on the west, a nd the parish boundary on the east and south. As discussed elsewhere, the state re vised their recommendation that a ll of DeSoto Parish should be designated attainment/unc lassifiable. EPA’s intended nonattai nment designation area is the area
within DeSoto Parish that lies within a rect angular area defined by UTM coordinates (See Figure 1 above). The nonattainment area excludes portions of Red River Parish, Louisiana that fall within this UTM-based boundary.

Figure 2: Dolet Hills Area of Analysis by the State

Sierra Club’s elevations for stacks and receptors were obtained from National Elevation Dataset (NED) GeoTiff data. GeoTiff is a binary file th at includes data descript ors and geo-referencing information necessary for extracti ng terrain elevations. The elevations were extracted from 1 arcsecond (30 meter) resolution NED files. The USEPA software program AERMAP v. 11103 was
used for these tasks.

Modeling Parameter: Source Characterization

Sierra Club modeled constant exit flowrate and temperat ure based on 100% load. No consideration was given of facility operation at less than 100% load. Stack parameters such as exit flow rate and temperature are typically lowe r at less than full load , having the effect of reducing pollutant dispersion and increasing pred icted air quality impacts. In addition, no

### 12 

### consideration was given to building or structure downwash. Do wnwash effects typically increase predicted concentrations near the facility. Th e state identified Internat ional Paper located 14 km
north of the Dolet Hills facil ity with annual emissions exceed ing 1,300 tpy as the only other large nearby emission source. However, no sources other than Dolet Hills were included in the modeling performed by the Sierra Club or the state.

Modeling Parameter: Emissions

The EPA’s Modeling TAD notes that for the purposes of modeling to characterize air quality for use in designations, the recommended approach is to use the most r ecent 3 years of actual emissions data and concurrent meteorological data. However, the TAD does provide for the flexibility of using allowable emissions in the form of the most recently permitted, (referred to as PTE or allowable) emissions rate.

The EPA believes that continuous emissions monitoring systems (CEMS) data provide acceptable historical emissions information when it is available, and that th ese data are available for many electric generating units. In the abse nce of CEMS data, th e EPA’s Modeling TAD highly encourages the use of AERMOD’s hourly varying emissions keyword HOUREMIS, or through the use of AERMOD’s variable emission s factors keyword EMI SFACT. When choosing one of these methods, the EPA believes that detailed throughput, ope rating schedules, and emissions information from the impacted source(s) should be used.

In certain instances, states and ot her interested parties may find that it is more advantageous or simpler to use PTE rates as part of their modeling runs. Specifically, a facility may have recently adopted a new federally enforceable emissions li mit, been subject to a federally enforceable consent decree, or implemented other fede rally enforceable mechanisms and control technologies to limit SO 2 

### emissions to a level that indicates compliance with the NAAQS. These new limits or conditions may be used in the application of AERMOD. In these cases, the Modeling TAD notes that the existing SO 2 

### emissions inventories used for permitting or SIP planning demonstrations should contain the nece ssary emissions information for designationsrelated modeling. In the ev ent that these short-term emissions are not readily available, they may be calculated using the methodology in Table 8-1 of Appendix W to 40 CFR Part 51 titled, “Guideline on Air Quality Models.”

As previously noted, the state included only Dole t Hills in its modeling but identified one other large emitter of SO 2 

### within 20 km in the area of analys is. The associated annual actual SO 2 

### emissions between 2012 and 2014 are summarized below.

Table 2: Actual SO 2 

### Emissions (2012 – 2014) from Facilities in the DeSoto Parish Area

Company ID Facility Name SO 2 

### Emissions (tons per year)

2012 2013 2014 CLECO Power LLC Dolet Hills 20,887 14,612 14,177 International Paper Co. Mansfield Mill 1,569 1,296 1,557 Total Emissions All Facilities 22,456 15,908 15,734

### 13 

### Initial state modeling for the pur pose of monitor siting used normalized hourly emissions and actual stack temperature and exit velocity from the CEMS for 2012-2014. Sierra Club modeling utilized hourly emissions data measured by th e CEMS from CAMD (2012-2014) and constant stack temperature and exit veloci ty. The state’s revised modeling utilized the Sierra Club model inputs for emissions and stack parameters, but the EPA reiterates that the emissions from IP were not included in the modeling analysis.

Modeling Parameter: Meteorology and Surface Characteristics

The most recent 3 years of meteorological data (concurrent with the most recent 3 years of emissions data) should be used in designations efforts. As noted in the Modeling TAD, the
selection of data should be based on spatial and climatologica l (temporal) representativeness. The representativeness of the data are based on: 1) the proximity of the meteorological monitoring site to the area under consideration, 2) the complexity of terrain, 3) the exposure of the meteorological site, and 4) the period of tim e during which data are collected. Sources of meteorological data include National Weather Se rvice (NWS) stations, s ite-specific or onsite data, and other sources such as universitie s, Federal Aviation Ad ministration (FAA), and military stations.

For the Dolet Hills area of analysis, surface meteorology was obtained for Shreveport Regional Airport located near Dolet Hill s. Integrated Surface Hourly (ISH) data for the 2012-2014 period
were obtained from the National Climatic Data Center (NCDC).

The state and Sierra Club used AERSURFA CE version 13016 to develop surface roughness, albedo, and daytime Bowen ratio values in a region surrounding the meteorological data
collection site. AERSURFACE was used to deve lop surface roughness in a one kilometer radius surrounding the data collection si te. Bowen ratio and albedo was developed for a 10 kilometer by 10 kilometer area centered on the meteorological data collection site. These micrometeorological data were processed for seasonal periods using 30 -degree sectors. Seasonal moisture conditions were considered average with winter months having no continuous snow cover.

Upper-air data are collected by a “weather balloon ” that is released twi ce per day at selected
locations. As the balloon is releas ed, it rises through the atmosphere , and radios the data back to the surface. The measuring and transmitting de vice is known as eith er a radiosonde, or
rawindsonde. Data collected and radioed back in clude: air pressure, height, temperature, dew point, wind speed, and wind dire ction. The upper air data were processed through AERMET Stage 1, which performs data extrac tion and quality control checks.

For Dolet Hills, the concurre nt 2012-2014 upper air data fr om twice-daily radiosonde measurements obtained at the most representati ve location were used. This location was the Shreveport, Louisiana measurement station. Th ese data are in Forecast Systems Laboratory (FSL) format and were downloaded in ASC II text format from NOAA’s FSL website. All reporting levels were downloaded and processed with AERMET (v14134).

### 14 

### Modeling Parameter: Geography and Terrain

The UTM NAD83 coordinate system (Zone 15) was used for identifying the easting (x) and northing (y) coordinates of the modeled sources and receptors. Stack locations were obtained from facility permits and prior modeling files provided by the state regulatory agency. The stack locations were then verified using aeria l photographs and confirmed with GIS.

The facility was evaluated to determine if it should be modeled using the rural or urban dispersion coefficient option in AERMOD. A Geographic Information System (GIS) was used to determine whether rural or urban dispersion coefficients apply to a site. Based on the AERSURFACE analysis, it was concluded that th e rural option would be used for the modeling summarized in this report. Please refer to Sec tion 4.5.3 of the Sierra Club modeling report for a discussion of the AERSURFACE analysis.

Modeling Parameter: Background Concentrations of SO 2



### The Modeling TAD offers two mechanisms for ch aracterizing background concentrations of SO 2 

### that are ultimately added to the modeled desi gn values: 1) a “first tier” approach, based on monitored design values, or 2) a tempor ally varying approach, based on the 99 th 

### percentile monitored concentrations by hour of day and s eason or month. For the Dolet Hills area of analysis, consistent with the background concentration identifi ed by the Sierra Club in their analysis, the state chose the 99 th 

### percentile of the annual distribution of daily maximum 1-hour concentrations averaged across 2011-2013 for the Bossier Parish monitor – the lowest measured background concentration in th e state. The background SO 2 

### concentration was added to the modeled fourth-highest daily maximum 1-hour SO 2 

### concentration. The background concentration for this area of analysis was de termined by the state to be 31.4 micrograms per cubic meter ( μ g/m 3 

### ), or 12.0 ppb, 3 

### and that value was incorporated into the final AERMOD
results.

Summary of Modeling Results

The AERMOD modeling parameters for the DeSoto Parish area of analysis are summarized
below in table 3:

Table 3: AERMOD Modeling Parameters for the DeSoto Parish Area of Analysis

DeSoto Parish Area of Analysis

AERMOD Version 15181 Dispersion Characteristics Rural

Modeled Sources 1

Modeled Stacks 1

3 The conversion factor for SO 2 (at the standard conditions applied in the ambient SO 2 reference method) is 1ppb
SO 2 = approximately 2.62 μ g/m 3 SO 2 at 25C and 1 atm.

### 15 

### Modeled Structures No

Modeled Fence lines - Total receptors 21201 Emissions Type Actual - CEM

Emissions Years 2012-2014 Meteorology Years 2012-2014

Surface Meteorology Station Shreveport Regional Airport (Shreveport, LA)

Upper Air Meteorology Station Shreveport, LA measurement
station

Methodology for Calculating Background SO 2 

### Concentration 99 th 

### percentile of the annual distribution of daily maximum 1-hour concentrations averaged

across 2011-2013 for Bossier
Parish Calculated Background SO 2 

### Concentration 12 ppb (31.4 μg/m 3 

### )

The results presented below in table 4 show the magnitude and geographic location of the highest predicted modeled concentr ation based on actual emissions.

Table 4: Max 99th Percentile 1-Hr SO 2 

### Conc.in DeSoto Parish Area Based on Actual Emissions

Averaging

Period Data Period Receptor Location SO 2 

### Concentration ( μ g/m 3 

### )

UTM Latitude UTM Longitude Modeled (including background) NAAQS

LDEQ revised modeling 99th Percentile 1-Hour Avg. 2012-2014 Not provided Not provided 194.5 196.5*

Sierra
Club modeling 99th Percentile 1-Hour Avg. 2012-2014 Not provided Not provided 218.7 196.5*

The state’s modeling 4 

### (with the LOWWIND3 non-default opti on) indicates that the predicted

99 th 

### percentile 1-hour average co ncentration within the chosen modeling domain is 194.5 μ g/m 3



### , or 74.31 ppb. This modeled concentration included the background concentration of SO 2 

### . This predicted value is graphically represented along with all the ot her receptors below in Figure 3. Sierra Club December modeling predicted 99 th 

### percentile 1-hour averag e concentration within the chosen modeling domain is 218.7 μ g/m 3 

### , or 83.55 ppb. This modeled concentration included

4 State modeling based on Sierra Club files and not the state’s normalized emission modeling.

### 16 

### the same background concentration of SO 2 

### . This predicted concentrations are graphically represented along with all othe r receptors with values abov e the NAAQS below in Figure 4.

Figure 3: Maximum Predicted 99 th 

### Percentile 1-Hour SO 2 

### Concentrations in the Dolet Hills Area of Analysis Based on Actual Emissions (LDEQ’s modeling using Sierra Club’s inputs)

### 17 

### Figure 4: Maximum Predicted 99 th 

### Percentile 1-Hour SO 2 

### Concentrations in the Dolet Hills Area of Analysis Based on Actual Emissions (Sierra Club)

As discussed previously, the st ate reran Sierra Club’s initial modeling factoring in a low wind non-default modification (beta option) to the mode l. The Sierra Club modeling provided a peak value of 218.7 μg/m 3 

### , above the standard of 196.5 μg/m 3 

### . The state reran that modeling using the proposed LOWWIND3 option, resulting in a peak value of 194.5 μg/m 3 

### , just below the standard (see Figure 4 above). As previously discussed, the EPA notes that th e use of beta options, such as ADJ_U* and LOWWIND3, in AERMOD for any re gulatory applications requires adherence with Appendix W, Section 3.2.2. This is fu rther explained in the EPA’s December 10, 2015 Memorandum titled, “Clarification on the Approval Process for Regulatory Application of the AERMOD Modeling System Beta Options.” Among other conditions, the use of beta options requires consultation with the appropriate EPA Regional Offices. Upon concurrence by the

### 18 

### EPA’s Modeling Clearinghouse, EP A Regional Offices may approve the use of these beta options for regulatory applicati ons as an alternative model. However, LDEQ performed air dispersion modeling intended to character ize air quality as a result of SO 2 

### emissions from Dolet Hills without prior consultation with and approva l from an EPA Regional Office, and therefore has not met the applicable regu latory requirements contained in Appendix W, Section 3.2.2. As a result, the EPA does not believe that the air quality modeling results obtained from the use of these beta options can be used as a reliable indica tor of attainment status in the area around Dolet Hills until appropriate alternative model approv al is granted or these beta options are promulgated as regulatory options in AERMOD through EPA rulemaking.

The Sierra Club modeling, and the state’s re vised modeling using LO WWIND3, only included constant stack velocity and temperature and di d not include building downwash or the nearby International Paper causing some uncertainty in the modeling results. The lack of downwash and variable temperature/velocity, wi th the non-inclusion of IP, however , generally bias the results of Sierra Club’s modeling low. As a result, we believe that Sierra Club’s modeling provides
sufficient information to determine that the area is not meeting the standard, and therefore we intend to designate it as nonattainment.

Jurisdictional Boundaries:

After the geographic area of anal ysis associated with the immedi ate area surrounding Dolet Hills, nearby sources which may potentially be contributing to elev ated levels of SO 2 

### , and background concentration was determined, existing jurisdic tional boundaries were considered for the purpose of informing our intended nonattainment area, speci fically with respect to clearly defined legal
boundaries. The EPA believes that while there are no clear jurisdictional boundaries that encompass our intended nonattainment area, UT M coordinates result in clearly defined
boundaries.

The state originally recommended an area in the S outheastern quadrant as unclassifiabl e and then
revised that recommendation to at tainment for all of DeSoto Parish. Based on our analysis and consideration of modeling results provided by Sie rra Club and the state, as well as other nearby sources such as IP, the EPA intends to designate portions of DeSoto Pari sh as nonattainment. As
discussed above when winds are from the north IP is a background source that could contribute significantly to some of the higher modeled values that are on the south side of Dolet Hills and very near the standard. Modeling results for monitor siting indicated the west side and south side were the two primary areas with high frequenc y of maximum values using normalized emissions.
The EPA believes that the IP faci lity has reported emissions that are large enough such that if they were explicitly modeled in accordance with the Modeling TAD would likely be shown to
contribute to the ambient concentrations that have already been modeled to show violations, or near violation, of the NAAQS. Inclusion of IP em issions may likely increase modeled values just
below the standard to exceedance levels. Ther efore, our intended ar ea includes portions of
DeSoto Parish that include the area of modeled exceedances and near exc eedances as well as the IP facility because of its likel y contribution to the modeled ambi ent concentrations resulting in additional potential NAAQS violations if IP were included in the modeling.

### 19 

### The EPA believes that our intended nonattainment area, consisting of the area around Dolet Hills and including Internatio nal Paper, is comprised of clearly defined boundaries, and we find these boundaries to be a suitably clear basis fo r defining our intended nonattainment area.

Conclusion

After careful evaluation of the state’s recommendation and supporti ng information, as well as all available relevant information, the EPA intends to designate the area around Dolet Hills in DeSoto Parish, Louisiana as nonattainment for the 2010 SO 2 

### NAAQS. Specifically, the intended nonattainment area is comprised of the portion of DeSoto Parish bounded by the following UTM Coordinates in meters (NAD83 Datum, Zone 15):

X Y

441287 3541019

441287 3562019

450500 3562019

450500 3541019

The nonattainment area excludes the portion of Red River Parish, Loui siana that falls within the area bounded by the listed UTM coordinates. Figure 1 above graphically i llustrates our intended
nonattainment area.

In its original submission, the state recomme nded that the area surrounding Dolet Hills, specifically the southeast quadrant of DeSoto Pari sh, be designated as unclassifiable based on a monitoring siting report. The stat e reran modeling using the input parameters provided by Sierra Club and additionally factored in a low wind sp eed modification. Based on this modeling, the state changed their recommended designation from unclassifiable to attainment. After careful
review of the state’s assessmen t, supporting documentation, and a ll available data, the EPA does not agree with the state’s recommendation fo r the area and cannot rely upon the modeling provided by the state, and intends to designate the area as nonattainment.

At this time, our intended designations for the st ate only apply to this area and the other area presented in this technical support document. Co nsistent with the conditions in the March 2, 2015 consent decree, the EPA will evaluate and designate all remaining undesignated areas in Louisiana by either December 31, 2017, or December 31, 2020.AECOM Mansfield Mill SO 2 Modeling Report Environment

60432329 March 2016 2



# Appendix B

Modeling Protocol Submitted to LDEQAECOM 978.905.2100 tel 250 Apollo Drive 978.905.2101 fax Chelmsford, MA 01824

J : \ AQES \ Projects \ International Paper 6890 \ Mans field, LA \ 500

- Deliverables \ LDEQ Protocol Letter

- final.docx March 8, 2016

Ms. Vennetta Hayes Louisiana Department of Environmental Quality
Air Permits P.O. Box 4313 Baton Rouge, LA 70821

- 4313

Subject: Proposed Modeling Methodologies for SO 2 DeS oto Parish, Louisiana Area Designations

Dear Ms

. Hayes

,

On February 11, 2016, the United States Environmental Protection Agency (EPA) Region 6 issued a letter to the Honorable John Bel Edwards, Governor of Louisiana. This letter was intended to inform Governor Edwards on the latest round of EPA’s area designations as they relate to the 1

- hour SO 2 National Ambient Air Quality Standards (NAAQS). This first round of designations w as targeted based on the consent decree enter ed into by EPA and the Sierra Club which was the result of the March 2, 2015 court ruling (Sierra Club vs. McCarthy, No. 3

- 13

- cv

- 3953). According to this ruling, the first round of designations must be made by EPA by July 2, 2 0 1 6. This letter indicated that parts of De S oto Parish in Louisiana (among other locations) were intended to be designated as

non

- attainment.

Attached to the letter was EPA’s technical support document (TSD) describing the analyses that were performed to define the boundary of the a rea designations. The non

- attainment area proposed by EPA was extended much further to the north (see Figure 1 of the EPA TSD) compared
to that proposed by Louisiana Department of Environmental Quality ( LDEQ ) in their November 17,
2015 recommendations. L DEQ recommended that the non

- attainment area for De S oto Parish be
limited to the southeast q uadrant of the parish (shown in Figure 2 of EPA’s TSD).

The primary (and only) source modeled to determine this area designation was the Dolet Hills Power Station

. EPA’s proposed non

- attainment area was extended approximately 10

- 15 kilometers to the north to include the International Paper ’s (IP) Mansfield Mill (a much smaller SO 2 emission source) even though the modeling presented by the Sierra Club and LDEQ indi cated the highest modeled impacts were to the west of Dolet Hills Power Station

.

N one of the technical analyses performed by EPA, the Sierr a Club, or LDEQ included the IP
Mansfield Mill. Based on the Sierra Club modeling (which only shows predicted impa cts above the NAAQS to the west of the Dolet Hills Power Station ), it is highly unlikely that IP Mansfield Mill’sAECOM

J : \ AQES \ Projects \ International Paper 6890 \ Mansfield, LA \ 500

- Deliverables \ LDEQ Protocol Letter

- final.docx 2

modeled impacts would significantly overlap the modeled exceedances due to the Dolet Hills Power Station (i.e., modeled contribution less than the 1

- hour SO 2 interim Significant Impact Level (SIL) of
7.9  g/m 3 )

.

The refore, the intention of th is letter is to inform the LDEQ on proposed modeling procedures that will differ from those outlined in EPA’s TSD provided with the February 11, 2016 area de signation
letter. IP proposes to perform additional modeling to determine the impact , if any, on the modeled exceedances of the 1

- hour SO 2 NAAQS that are predicted in the vicinity of the Dolet Hills P ower Station

.

The modeling will be performed in accordance with the approaches outlined in the EPA’s TSD and utilized by the Sierra Club and LDEQ with the following exception s to either refine the analysis or address potential deficiencies identified by EPA in their TSD :

1. All modeling will be conducted using DEFAULT model options.

2. Updates will be made to account for actual flow rates and /or temperatures in the hourly estimates of the Dolet Hills Power Station emissions and stack parameters.

3. Updates will be made to include building downwash for the Dolet Hills Power Station

.

4. AERMET Version 15181 will be used in the updated modeling.

5. IP Mansfield Mill sources will be included using their allowable emission rates for all SO 2 sources except Power Boiler #1 and #2 which will be modeled using representative actual maximum hourly emission rate s . Th e representative actual maximum hourly emissi on rate s will be determined by using the 99 th percentile (or greater) emission rate for each Power
Boiler based on operations during the 2012

- 2 0 14 period. Overall, this approach is conservative in that it utilizes a representative maximum hourly emission rate for every hour of the year as opposed to actual hourly emissions.

6. The IP Mansfield Mill will include building downwash.

7. The modeling will be conducted using one comprehensive receptor grid encompassing the area surrounding both facilities . The gri d will extends out a minimum of 20 kilometers in all directions from each facility. The grid will be based on the following specifications:

a. 25

- meter spacing around each facility’s ambient air boundary ;
b. Beyond the ambient air boundary from each facility , 100

- meter spaced receptors
will be used out to 3

- 5 km depending on the direction from the facilities ;

c. Beyond the 100

- meter spaced receptors a 250

- meter spaced grid will be used out
and additional 4

- 8 kilometers from each facility depending on the directi on ;
d. Beyond the 250

- meter spaced receptors a 500

- meter spaced grid will be used out
and additional 5 kilometers ; and

e. Beyond the 500

- meter spaced receptors a 250

- meter spaced grid will be used out
and additional 10 kilometers.AECOM

J : \ AQES \ Projects \ International Paper 6890 \ Mansfield, LA \ 500

- Deliverables \ LDEQ Protocol Letter

- final.docx 3

8. Ambient background concentrations will be updated based on 2013

- 2015 data for the Shreveport Monitor. 2011

- 2013 was used as part of the TSD, however that data only represented 2013 as the monitor was shut down in 2011 and 2012. In addition , rather than

c onservatively adding the modeled design concentration with the monitored design
concentration for this analysis, as a refinement, t he ambient background will be combined
with modeled concentrations on a seasonal hour

- of

- d ay basis in accordance with EPA gui dance in their March 1, 2011 clarification memo 1 and as outlined in the SO 2 Modeling Technical Analysis Document (TAD) 2

.

IP looks forward to receiving any comment s that LDEQ has on these proposed modeling procedures

.

Yours sincerely,

Jeffrey Connors Air Quality Meteorologist jeffrey.connors@aecom.com

cc \ Tegan Treadaway (LDEQ) Louis Derose (IP) Chris Gann (IP)
Brian E Heim (IP) Sheryl Watkins (AECOM)

1 http://www.epa.gov/ttn/scram/guidance/clarification/Additional_Clarifications_AppendixW_Hourly

- NO2

- NAAQS_FINAL_03

- 01

- 2011.pdf

2 Available at: https://www3.epa.gov/airquality/sulfurdioxide/pdfs/SO2ModelingTAD.pdfAECOM Mansfield Mill SO 2 Modeling Report Environment

60432329 March 2016 3



# Appendix C

Modeling Archive CD