## A IR 

## D ISPERSION 

## M ODELING 

## P ROTOCOL 

## (R EVISION 

## 1)

A NADARKO 

## P ETROLEUM 

## C ORPORATION 

##  EGOM D RILLING 

## , C OMPLETION 

## , AND 

## M AINTENANCE 

## P ROJECT



### Prepared for:

A NADARKO 

### P ETROLEUM 

### C ORPORATION

1201 Lake Robbins Drive

The Woodlands , TX 77380



### Prepared by:

T RINITY 

### C O NSULTANTS

301 Main Street

. Suite 900 Baton Rouge, LA 70825 (225) 346

- 4003

August 201 3

Project 131901. 00 20Anadarko ii Trinity Consultants



## T ABLE OF 

## C ONTENTS

1. I NTRODUCTION

................................ ................................ ................................ .................. 6

1.1 P ROJECT D ESCRIPTION

................................ ................................ ................................ ........ 6
1.2 P ROJECT L OCATION

................................ ................................ ................................ ............ 7
1.3 D ESCRIPTION OF M ODELING P ROCEDURES

................................ ................................ ........ 9

1.4 C ONTENTS OF THE M ODELING P ROTOCOL

................................ ................................ ....... 10

2. S OURCE D ESCRIPTION

................................ ................................ ................................ .... 11
2.1 D ESCRIPTION OF P ROPOSED OCS S OURCE

................................ ................................ ....... 11

2.2 E MISSION S OURCES

................................ ................................ ................................ ........... 12

2.3 P OTENTIAL E MISSIONS

................................ ................................ ................................ ...... 12

2.4 Q/D A NALYSIS

................................ ................................ ................................ .................. 12

3. C LASS II A IR Q UALITY D ISPERSION M ODELING R EQUIREMENTS

.............................. 14

3.1 PSD S IGNIFICANCE A NALYSIS

................................ ................................ .......................... 15

3.1.1 P RE

- C ONSTRUCTION M ONITORING A NALYSIS

................................ .................... 18

3.1.2 S PECIAL C ONSIDERATIONS FOR PM 2.5

................................ ................................ . 18

3.2 A DDITIONAL I MPACTS A NALYSIS

................................ ................................ ..................... 20

3.2.1 G ROWTH A NALYSIS

................................ ................................ ............................. 21

3.2.2 S OILS AND V EGETATION A NALYSIS

................................ ................................ .... 21

3.2.3 V ISIBILITY A NALYSIS

................................ ................................ .......................... 21

4. C LASS I A IR Q UALITY D ISPERSION M ODELING R EQUIREMENTS

................................ 23

4.1 C LASS I A REA PSD I NCREMENT

................................ ................................ ....................... 23

4.2 C LASS I AQRV A NALYSES

................................ ................................ ............................... 24

4.2.1 D EPOSITION

................................ ................................ ................................ .......... 25

4.2.2 V ISIBILITY

................................ ................................ ................................ ............ 26

4.2.3 O ZONE

................................ ................................ ................................ .................. 30

5. M ODELING M ETHODOLOGY AND I NPUTS

................................ ................................ ...... 32
5.1 M ODEL S ELECTION

................................ ................................ ................................ ........... 32

5.2 M ODEL D OMAINS

................................ ................................ ................................ .............. 33
5.3 R EPRESENTATION OF M ODELED S OURCES

................................ ................................ ....... 34

5.4 R ECEPTOR L OCATIONS FOR C LASS I A REAS

................................ ................................ ..... 35

5.5 R ECEPTOR L OCATIONS FOR C LASS II A REAS

................................ ................................ ... 35
5.6 E MISSIONS S PECIATION

................................ ................................ ................................ .... 35

5.7 T ERRAIN P ROCESSING FOR C LASS II A NALYSIS

................................ ............................... 36

5.8 B UILDING D OWNWASH

................................ ................................ ................................ ..... 36
5.9 B ACKGROUND C ONCENTRATIONS

................................ ................................ .................... 36

5.10 CALMET (M ETEOROLOGICAL D ATA ) P ROCESSING

................................ ........................ 36

5.11 CALPUFF P ROCESSING

................................ ................................ ................................ .... 37
5.11.1 O ZONE

................................ ................................ ................................ ................. 37

5.11.2 A MMONIA

................................ ................................ ................................ ............ 38

5.11.3 CALPUFF P ROCESSING C ONTROL

................................ ................................ ..... 38
5.12 CALPOST P OSTPROCESSING A NALYSIS

................................ ................................ .......... 38Anadarko iii Trinity Consultants

6. M ODELING R EPORT C ONTENTS

................................ ................................ ..................... 40Anadarko iv Trinity Consultants 

## L IST OF 

## T ABLES

T ABLE 1

- 1. L OCATION OF L EASE B LOCKS R ELATIVE TO N EAREST C LASS I A REAS A ND S HORELINE

. 7

T ABLE 3

- 1. A PPLICABLE PSD A IR Q UALITY L EVELS

................................ ................................ .......... 15

T ABLE 4

- 1

. C LASS I A REA PSD I NCREMENTS & M ODELING S IGNIFICANCE L EVELS

......................... 23

T ABLE 4

- 2. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR B RETON NWR

................................ ........... 28

T ABLE 4

- 3. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR S T

. M ARKS

................................ ................ 29

T ABLE 4

- 4. A NNUAL A VERAGE B ACKGROUND V ALUES FOR B RETON & S T

. M ARKS

........................ 29

T ABLE 5

- 1. V ERTICAL G RID S TRUCTURE

................................ ................................ ............................ 34Anadarko v Trinity Consultants 

## L IST OF 

## F IGURES

F IGURE 1

- 1. A NADARKO ’ S L EASE B LOCKS IN E ASTERN G ULF OF M EXICO

................................ .......... 8

F IGURE 3

- 1. G ENERAL PSD M ODELING F LOWCHART

................................ ................................ ......... 17

F IGURE 5

- 1. V ISTAS RHR M ODEL D OMAINS

................................ ................................ ...................... 33Anadarko Petroleum, Inc. 6 Trinity Consultants 

## 1. I NTRODUCTION



## 1.1 P ROJECT 

## D ESCRIPTION

Anadarko Petroleum Corporatio n (Anadarko) is applying for a pre

- construction (PSD) and operating permit (Title V) for conducting exploratory drilling and other activity on the Outer Continental Shelf (OCS) of the Gulf of Mexico . The proposed project will consist of t he initial drilli ng phase

, a well completion phase and a maintenance operation phase. The proposed activities are planned to be

conducted at various lease blocks within the Desoto Canyon using a dynamically positioned drillship and associated support vessels in the Easter n Gulf of Mexico (EGOM), east of the 87.5 degree longitude. A map outlining the “wedge” in the Gulf of Mex ico (GOM) identified by the boundary presented on the map located in Figure 1

- 1 . Within the wedge there are both active lease blocks (currently lease d or available for lease) and lease blocks that could potentially be available for lease by Bureau of Ocean Energy Management (BOEM) in the future. The area within the boundary line identified as “wedge”

, is bounded by the following limits.

1. The 87.5 longi tude line to the west (Environmental Protection Agency Jurisdiction)

2. The 86.88 longitude line to the east (Military Mission Line)

3. The limit of 100 miles to the shore in the BOEM Central Planning area

4. The limit of 125 miles to the shore in the BOEM Eastern Planning area

A n OCS source is considered PSD major if potential emissions of any PSD

- regulated pollutant exceed the major source thresholds of 250 tons per year (tpy) and the operations are considered a major source under the PSD program . The PSD progra m regulates the emissions of all criteria pollutants and several non

- criteria pollutants such as total reduced sulfur compounds, sulfuric acid

mist (H 2 SO 4 ) , and fluorides (not including hydrogen fluoride).

Based on the preliminary project analysis and em issions calculations, it is expected that the proposed

OCS source will be subject to requirements of the PSD program and PSD review may be required for particulate matter (PM), particulate matter with an aerodynamic diameter less than 10 microns (PM 10 ), pa rticulate matter with an aerodynamic diameter less than 2.5 microns (PM 2.5 ), nitrogen oxides ( NO X ), sulfur dioxide (SO 2 ), carbon monoxide (CO), greenhouse gases (GHG), and volatile organic compounds (VOC)

. Accordingly, Anadarko is currently preparing a pe rmit application for the PSD construction permit as well as the 5

- year renewable Title V operating permit.

A s a part of the PSD /Title V application, an air quality modeling analysis will be presented to demonstrate that the new facility will not :

 cause or significantly contribute to a violation of the National Ambient Air Quality Standards (NAAQS) ;

 cause ambient concentrations that exceed PSD Increments, or

 cause any other adverse impacts to the surrounding area [i.e. impacts on soil and vegetation,
vis ibility degradation, etc.].

Additionally, based on the location of the proposed drilling sites and preliminary analysis of project emissions, air quality modeling analyses of the impacts on federally protected Class I areas, aAnadarko Petroleum, Inc. 7 Trinity Consultants

component of a PSD review, will also need to be performed to demonstrate compliance with PSD Class I area Increment standards and air quality related values (AQRV) thresholds for regional haze and deposition

. 1

In accordance with 40 CFR 52.21(p), “ the Federal Land Manager and the F ederal official charged with direct responsibility for management of such lands have an affirmative responsibility to protect the air quality related values (including visibility) of such lands and to consider, in consultation with the Administrator, wheth er a proposed source or modification will have an adverse impact on such
values .” Therefore, the Federal Land Manager ( FLM ) has the authority to request that proposed PSD major sources perform Class I modeling to demonstrate that the AQRVs of Class I area s are not adversely affected.

This modeling protocol which includes the methodology Anadarko is proposing for both Class I and Class II modeling analyse s have been prepared and is being provided for submitt al to the FLM and U.S. EPA Region 4

.



## 1.2 P ROJECT 

## L OCATION

Anadarko has identified all lease blocks currently available for drilling operations in EGOM within

the lease block and has determined which of these lease blocks are closest to all nearby Class I and

nearest state shoreline areas. Table 1

- 1 belo w provides the approximate distance of the worst

- case (nearest) lease blocks within the area to where each Class I area is located relative to the lease block, the corresponding FLM for each Class I area , and the nearest lease block to shoreline for Class II modeling . A map showing the location of worst

- case lease blocks relative to the nearest Class I areas and surrounding onshore areas is provided in Figure 1

- 1

.

T ABLE 1

- 1. L OCATION OF L EASE B LOCKS R ELATIVE TO N EAREST C LASS I A REAS A ND S HORELINE

Class I Area (State) &
Nearest State Shoreline Lease
Block Direction Distance (km) Federal Land Manager

Breton NWR (LA) 141 NW 167 U.S. Fish & Wildlife Service (FWS) St. Marks NWR (FL) 149 NE 286 U.S. Fish & Wildlife Service (FWS) Bradwell Bay Wilderness (FL ) 149 NE 282 U.S. Forest Service (FS)

Nearest State Shoreline 141 NW 16 1

1 Anadarko ’s Project lease blocks are located within three federally protected Clas s I areas in the Southern United
States.Anadarko Petroleum, Inc. 8 Trinity Consultants F IGURE 1

- 1

. A NADARKO ’ S L EASE B LOCKS IN E ASTERN G ULF OF M EXICOAnadarko 9 Trinity Consultants 

## 1.3 D ESCRIPTION OF 

## M ODELING 

## P ROCEDURES

On behalf of Anadarko , Trinity Consultants (Trinity) is submitting this air quality modeling protocol to present U.S. EPA Region 4 with a description of the proposed modeling procedures and data resources in advance of a PSD permit application, which will provide the results o f all modeling analyses. The methodology described in the protocol will be further utilized in the final modeling report to demonstrate compliance with applicable standards. Since the closest receptor for both Class I and Class II modeling is more than 5 0 km from the nearest lease block and worst

- case drilling location, the air quality impact analyses involve long

- range transport and dispersion conditions. Hence, CALPUFF air dispersion modeling system will be used for the modeling analysis

.

The CALPUF F air dispersion modeling system is currently the U.S. EPA recommended model for assessment of long

- range pollutant transport and chemical transformation. 2 Trinity will conduct the modeling analyses in a manner that conforms to the applicable rules and re quirements for dispersion modeling, including rules and guidance provided in :  U.S. EPA: Guideline on Air Quality Models , 40 CFR Part 51

- Appendix W (Revised, November 9, 2005) (referred to hereafter as Guideline ),
 T he applicable guidance memorandum from S upport Center for Atmospheric Modeling (SCRAM) website, the Draft New Source Review Workshop Manual 3

,  T he Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report 4

,  Reassessment of the Interagency Workgroup on Air Quality Modeling (I WAQM) Phase 2 Summary Report: Revisions to Phase 2 recommendations(Draft 2009 report) 5

,  T he Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) Revised Phase I Report (FLAG 2010 report) 6

,  T he U.S. EPA’s Guidance for Estimating Natural Vi sibility Conditions under the Regional
Haze Rule 7

,  T he U.S. EPA’s Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations 8

,  P revious communications between Trinity and EPA Region 4

, 9 and
 P revious communicati ons between Trinity and the FLM for the three Class I areas. 10

2 40 CFR Part 51, Appendix A to Appendix W (Revised, November 9, 2005).

3 EPA’s New Source Review Workshop Manual (DRAFT) (1990).

4 U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long

- Ran ge Transport Impacts , Research Triangle Park, North Carolina, EPA

- 454/R

- 95

- 006, December 1998.

5 U.S. EPA, Reassessment of IWAQM Phase 2 Summary Report: Revisions to Phase 2 Recommendations

, Research Triangle Park, North Carolina, EPA

- 454/R

- 09

- XXX, May 200 9 Draft.

6 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Division, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 20 10.

7 U.S. EPA, Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule , September
2003.

8 U.S EPA, Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, July 6, 2005.

9 Based on P ersonal Communication: Phone conversation between Mr. Stan Krivo (EPA Region 4 ) and Mr. Rahul Pendse (Trinity) on September 21, 2012.Anadarko 10 Trinity Consultants

.



## 1.4 C ONTENTS OF THE 

## M ODELING 

## P ROTOCOL

The remainder of this modeling protocol is organized as follows:

 Section 2 provides a description of the OCS source

, summary of emission sources and
pote ntial emissions , and a description of Q/d analysis ;  Section 3 describes the applicable modeling requirements

, which includes a discussion of the steps involved in a Class II Area modeling analysi s;  Section 4 describes the applicable modeling requirements , which includes a discussion of the steps involved in a Class I Area modeling analysis;
 Section 5 describes the model ing methodology and inputs , which includes a discussion of the selected dispersion models, meteorological dat a, representation of source s, background concentrations, building downwash analysis, receptor locations

, a nd other model inputs ; and
 Sect ion 6 describes the content of the modeling report that will be submitted to the FLM and U.S. EPA Region 4 for review

.

10 Based on Personal Communication: Phone conversation between Ms. Jill Webster (FWS) and Mr. Rahul Pendse (Trinity) on Oct ober 12, 2012; E

- mail from Ms. Jill Webster (FWS) to Mr. Dhesikan Venkatesan (Trinity) sent on October 10, 2012; and Phone conversation between Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012.Anadarko 11 Trinity Consultants 

## 2. S OURCE 

## D ESCRIPTION



## 2.1 D ES CRIPTION OF 

## P ROPOSED 

## OCS S OURCE

The exploratory drilling activity will consist of the initial drilling phase, a well completion phase

and /or a maintenance operation phase. Anadarko is requesting the flexibility to drill one or more wells in any of the lea se blocks provided in Section 1

- 2 while complying with any operational and
emission limitations specified in the air permits that will be issued. The proposed operations will be conducted using the drillship Blackhawk

, and associated support vessels.

The Blackhawk is a dynamically

- positioned drillship that is designed for operation in the deep water. As a dynamically

- positioned drillship, it maintain their position over the desired location by using the
computer

- controlled thruster propellers rather than by using anchors and is not required to be attached to the seabed in order to establish or maintain its position like a traditional drillship. As discussed in Section 1, 40 CFR 55.2 states that a vessel shall only be considered an OCS source when

“ P ermanently or temporarily attached to the seabed and erected thereon and used for the purpose of exploring, developing or producing resources therefrom...” Therefore, Blackhawk will qualify as an

OCS source after the drillship is tem porarily or permanentl y attached to the seabed during the proposed operations

.

T he major sources of emissions on the drillship as well as the support vessels will primarily consist of

diesel

- fired internal combustion engines and fuel storage tanks. The miscellaneous mainten ance activities (such as welding, painting) resulting in air emissions will be conducted on the drillship. The permit application will provide a detailed description of all the sources of air pollution including diesel engines, fuel storage tanks, and mis cellaneous activities.

The associated support vessels will include a combination of crew boats and work boats

, stimulation vessels, tug and

/or barge boats that will be used to transport personnel, supplies, and fuel to the drillship, as required, during t he entire duration of the proposed project

. As it is presently not known which specific vessels will be available when the drilling commences, the support vessels will be used interchangeably depending upon availability. For purposes of the air permit ap plications and the modeling analysis, the worst

- case emissions from the each category of the support vessels will be

utilized

. The emissions from the support vessels will be considered for the modeling analysis while the support vessels are at the drillsh ip, and while enroute to or from the drillship when within 25 miles of the drillship. All assumptions made for estimating the worst

- case support vessel emissions as well as all support vessels and their respective functions will be appropriately documente d in the final modeling r eport of the permit application.

In addition to the boats, the support vessel fleet will also include a helicopter that will be used for transporting su pplies and personnel. The helicopter typically makes two trips per day to the drillship. Since the helicopter takes small amount of time to travel 25 miles from the drillship , expected airAnadarko 12 Trinity Consultants

emissions are negligible. Hence based on previous communications and discussion s with U.S. EPA Region 4 , the helicopter emissions are not inclu ded in the PSD permitting effort

. 11



## 2.2 E MISSION 

## S OURCES

The sources of emissions for Blackhawk primarily consist of :  internal combustion engines,
 painting operation,
 welding operation,
 dust collectors,
 mud

- degassing operation

,  water blasting operation,
 miscellaneous equipment, and
 fuel storage tanks.

For t he support vessels, the emission sources include internal combustion engines and fuel storage
tanks

. The methodology used to deter mine the “worst

- case” drillship and support vessel emission s model ed will be described in details in the application

.



## 2.3 P OTENTIAL 

## E MISSIONS

As previously mentioned, the proposed project will consist of the initial drilling phase

, a well completion phase

, and /or a maintenance operation phase. The well completion and mainte nance operation phase are expected to have lower emissions than the drilling phase. The permit application will include the detailed description of the maximum hourly (1

- hour)

, maximum daily (24

- hour) and annual emissions resulting from the proposed explo ratory drilling , completion, and maintenance

activit ies o ver entire duration of the project

. The worst case emissions will be utilized for air dispersion modeling.



## 2.4 Q/D A NALYSIS

Anadarko will complete the Q/d calculation based on the potential

- to

- emit from the proposed project to assess potential impacts of the proposed drilling operations on the nearest Class I area s . The Q/d analysis compares the ratio of the sum of proposed annualized maximum 24

- hour emission rates of all visibility impairing pollutants (in tons per year) and the distance to the nearest Class I area (in km) to a threshold value of 10, as determined by the FLM.

The “Q” is the combined emissions increase from a source of SO 2 , NO X , PM 10 , and H 2 SO 4 in tons per year (tpy) based on annualize d 24

- hour maximum allowable emissions and “d” is the nearest distance

to a Class I area in km from the source

. 12 Emissions from sources that operate intermittently or seasonally will be adjusted to account for year round operation. Based on the prelimina ry analysis, a
Class I area AQRV analysis is required for this project because the Q/d ratio for the proposed source

11 Personal Communication: Phone con versation between Mr. Stan Krivo (EPA Region 4 ) and Mr. Rahul Pendse (Trinity) on September 21, 2012.

12 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Division, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 2010.

.Anadarko 13 Trinity Consultants

is expected to be greater than 10. Although Anadarko is still in the process of finalizing potential emission rates, Anadarko does not exp ect the Q/d to be less than 10. A copy of the Q/d analysis will be included in the final modeling report.Anadarko 14 Trinity Consultants 

## 3. C LASS 

## II A IR 

## Q UALITY 

## D ISPERSION 

## M ODELING 

## R EQUIREMENTS

As the proposed OCS source will be subject to the PSD program requirements, an air quality ana lysis is required to demonstrate that emissions of these pollutants do not cause or contribute to a violation of a National Ambient Air Quality Standard (NAAQS) or exceed a Class II area PSD Increment. Per
Guideline , this is accomplished by conducting an Air Dispersion Modeling a nalysis. A Class II PSD Air Dispersion Modeling Analysis may consist of two distinct phases:

 The first phase, PSD significance analysis, is a screening analysis. The significance analysis determines whether 40 CFR 52.21 requires a full impact analysis for compliance. The significance analysis considers only the emissions associated with the proposed project to determine if the net emissions changes will have a significant impact upon the surrounding area. A “significant” impact occurs when the modeled ambient concentration resulting from the modeled emission rates equals to or exceeds applicable ambient concentration thresholds commonly referred to as the Significant Impact Levels (SILs) also known as Modeling Significance Level s (MSLs)

. In addition, the significance analysis determines the Significant Impact Area ( SIA ) and whether the applicant is exempt
from preconstruction ambient monitoring requirements for the proposed project

.

 The second phase is a “ full impact ” or “cum ulative” analysis. For pollutants with modeled concentrations greater than the SIL, PSD regulations require a NAA QS analysis and a PSD Increment analysis. A full impact analysis is performed at each off

- property receptor
where the maximum concentration e xceeds the applicable SIL as determined in the significance analysis. The NAAQS analysis demonstrates that the post

- project emissions in conjunction with other applicable emissions from existing sources will not cause nor

contribute to an exceedance of th e applicable air quality standard. The PSD Increment analysis demonstrates that the proposed project in conjunction with other applicable emissions from existing sources will neither cause nor contribute to an exceedance of the applicable air quality stan dard.

Table 3

- 1 lists the SILs, NAAQS, and PSD Increments for all relevant PSD

- regulated pollutants for

this dispersion modeling analysis

.Anadarko 15 Trinity Consultants T ABLE 3

- 1. A PPLICABLE PSD A IR Q UALITY L EVELS

Pollutant Averaging

Period PSD

Modeling

SIL
(  g/m 3 ) Primary and

Secondary
NAAQS
(  g/m 3 ) Class II

Area PSD

Increment (  g/m 3 ) Significant

Monitoring

Concentration
(  g/m 3 )

CO 1

- hour

8

- hour 2,000

500 40,000 (35 ppm) 1
10,000 (9 ppm) 1 --

-- --

575

SO 2 9 3

- hour

24

- hour

Annual

1

- hour 8 25

5

1

-- 1,300 (0.5 ppm) 1

--

-- 196 (0.075 ppm) 4 512

91

20

-- --

13

--

--

NO 2 Annual

1

- hour 7 1

-- 100 (0.053 ppm) 2
188 ( 0.100 ppm ) 4 25

-- 14

--

PM 10 24

- hour

Annual 5

1 150 3

-- 30

17 10

--

PM 2.5 24

- hour

Annual 1.2

0.3 35 5

1 2 6 9

4 4

--

1 Not to be exce eded more than once per year.
2 Annual arithmetic average.
3 Not to be exceeded more than once per year on average over 3 years.
4 3

- year average of the 98 th percentile of the annual distribution of daily maximum 1

- hour concentrations.
5 98 th percentile of concentrations in a given year, averaged over 3 years.

6 Annual arithmetic mean from single or multiple monitors, averaged over 3 years.

7 PSD Increments, Modeling SILs, and Monitoring De Minimis Concentration level for the 1

- hour NO 2 standard
have not be en proposed yet. However, interim modeling significance levels of 4 ppb was provided by EPA in general guidance implementation memo dated June 28, 2010.
8 PSD Increments, Modeling SILs, and Monitoring De Minimis Concentration level for the 1

- hour S O 2 stan dard have not been proposed yet. However, interim modeling significance levels of 3 ppb was provided by EPA in general guidance implementation memo dated August 23, 2010.
9 The existing annual and 24

- hour SO 2 standards will be revoked one year after the effective date in areas with a designated status for the revised SO 2 NAAQS, per 40 CFR 50.4(e).

A summary of the tasks that are performed in a standard PSD Air Dispersion Modeling analysis is presented in the flow chart provided as Figure 3

- 1. Each of th e principle steps involved in a PSD Air Dispersion Modeling analysis are discussed in detail below. The dispersion modeling analysis will be conducted in a manner that conforms to the applicable rules and requirements for dispersion modeling issued by the U.S. Environmental Protection Agency (EPA ). 13



## 3.1 PSD S IGNIFICANCE 

## A NALYSIS

The Significance Analysis is conducted to determine whether the emissions associated with the proposed OCS source would cause a significant impact upon the area surrounding the OCS s ource

. As shown in Figure 3

- 1, if the highest modeled ambient concentrations for a pollutant for all

13 40 CFR 51, Appendix W, Revision to Guideline on Air Quality Models, November 9, 2005 ; and EPA’s New Source Review Workshop Manual (DRAFT) (1990).Anadarko 16 Trinity Consultants

averaging periods are less than the applicable SILs shown in Table 3

- 1, when emission from only the project are modeled, then further analyses ( i.e., NAAQ S and PSD Increment) are not required for that pollutant and the project’s impact is considered not significant . If, however, modeled impacts equal

to or exceed the SIL for any averaging period, a full impact (i.e., NAAQS and PSD Increment ) analysis is re quired for that pollutant to demonstrate that the project neither causes nor contributes to any exceedances. A special consideration shall be given to PM 2.5 since direct comparison of the primary PM 2.5 concentration with PM 2.5 SIL is not allowed without p rior approval from the regulatory agency. Refer to Section 3.1.3 for further discussion regarding this topic.

Based on t he preliminary emission calculations and previous experiences

, Anadarko expects that concentration of all pollutants will be less th an their respective SILs. Hence, in that case, full impact analysis will not be required for these pollutants. Hence this protocol does not address requirements for the full impact analysis. If the significance levels for applicable pollutants and avera ging periods

are exceeded in the final modeling analyses, an addendum to this protocol will be submitted to EPA Region 4 for review and approval.Anadarko 17 Trinity Consultants F IGURE 3

- 1

. G ENERAL PSD M ODELING F LOWCHARTAnadarko 18 Trinity Consultants



### 3.1.1 P RE



### - C ONSTRUCTI ON 

### M ONITORING 

### A NALYSIS

In addition to determining whether the applicant can forego further modeling analyses, the PSD Significance Analysis is also used to determine whether the applicant is exempt from ambient monitoring requirements. To determine whethe r pre

- construction monitoring should be considered, the maximum impacts attributable to the emissions increases from a project are compared with the Significant Monitoring Concentrations (SMC s ) shown in Table 3

- 1. If either the predicted modeled impact fr om an emissions increase or the existing ambient concentration is less than the SMC , an applicant is exempt from pre

- construction ambient monitoring. If the predicted modeled impact is equal to or greater than the SMC , an applicant may provide existing da ta representative of ambient air quality in the affected area or, if such data are not available, collect background air quality data. 14

If the predicted modeled impacts are lower than the SMC

, Anadarko expects that pre

- construction monitoring for this p roject will not be required by U.S. EPA Region 4

. If the predicted modeled impacts equal to or exceed the SMC s , Anadarko will submit an addendum to this protocol and seek approval from EPA Region 4

.

Additionally, although no SMCs have been established fo r ozone, 40 CFR 52.21(i)(5)(i) specifies that for any net emissions increase of 100 tons per year or more of VOC or NO X subject to PSD , an applicant would be required to perform an ozone i mpact analysis

. As the NO X emissions from the proposed OCS source a re expected to be greater than 100 tons per year, Anadarko will be subject to the requirements of 40 CFR 52.21(i)(5)(i). Due to the remote offshore location of the proposed operations

, very minimal contribution in the formation of ozone is expected from t he proposed operation

. 

### Since an adequate ozone formation model is not available for this type of a single source application

, Anadarko proposes to address this requirement using qualitative approach similar to the one described in the preliminary statemen t of basis for permit no. OCS

- EPA

- R4006 prepared by the EPA Region 4

. 15



### 3.1.2 S PECIAL 

### C ONSIDERATIONS FOR 

### PM 2.5

On May 16, 2008, U.S. EPA issued the final PM 2.5 New Source Review (NSR) Implementation Rule, which requires sources to conduct an ambient air quality analysis for PM 2.5 in accordance with 40
CFR §52.21(m). 16 While the preamble to this rule states that no changes to the PSD regulations on air quality impact analyses were made for purposes of implementing the PM 2.5 NSR program, conducting
an ambient air quality analysis using the current regulatory air dispersion models for a pollutant like
PM 2.5 , which can be formed from precursors through atmospheric reactions downwind of an industrial

source p oses several technical difficulties. Therefore, when implem enting the current U.S. EPA

recommended model and relevant PS D modeling guidance, sources need to evaluate ambient impacts from direct total (filterable and condensable) PM 2.5 emissions and secondary PM 2.5 emissions

.

EPA recommended in a m emorandum that the highest average of the modeled annual averages of

PM 2.5 concentrations based on 5 years of National Weather Service data or the highest modeled

14 U.S. E PA New Source Review Workshop Manual (Draft, 1990), pages C.18

– 19.

15 U.S. EPA Region 4, Preliminary Determination & Statement of Basis Outer Continental Shelf Air Permit OCS

EPA

- R4006 , August 19, 2011



### .

16 Federal Register, Vol. 73, p. 28,321.Anadarko 19 Trinity Consultants

annual average of PM 2.5 concentration based on 1 year of site

- specific meteorological data be compared to t he annual SIL. 17 Similarly, it was recommended that the highest average of the

maximum 24

- hour averages of PM 2.5 concentrations based on 5 years of National Weather Service data or the highest modeled 24

- hour average of PM 2.5 concentration based on 1 yea r of site

- specific meteorological data be compar ed to the 24

- hour SIL. Anadarko is proposing to use the annual an d

24

- hour options based on three year meteorological dataset (2001

- 2003) developed by the Visibility Improvement State and Tribal Association of the Southeast (VISTAS) for the PSD Class II impact

assessments

.

On September 29, 2010, the U.S. EPA issued a final ruling establishing several components for making PSD permitting determinations for PM 2.5 . As such, the promulgated PSD increments, SILs

, and SMCs for PM 2.5 hav e been incorporated into Table 3

- 1 of this modeling protocol.

The EPA has historically allowed the use of screening tools to help facilitate the implementation of the PSD program and streamline the permitting process in circumstanc es where proposed construction is projected to have an insignificant (or de

- minimis) impact on air quality. These screening tools have included SERs, SILs, and SMCs

. The EPA established a SER for PM 2.5 in a 2008 rule and promulgated SILs and an SMC for P M 2.5 in 2010

. 18 However, on January 22, 2013, the U.S. Court of Appeals for the District of Columbia Circuit vacated the SMC for PM 2.5 and two provisions in EPA’s PSD regulations containing SILs for PM 2.5

. 19 The Court concluded that the PM 2.5 SMC provision s (40 CFR 51.166(i)(5)(c) and 40 CFR 52.21(i)(5)(i)(c)) were inconsistent with the requirements of Section 165(e)(2) of the CAA. The Court granted the EPA’s request to remand and vacate the SIL provisions in Sections 40 CFR 51.166(k)(2) and 40 CFR 52.21(k )(2) of the regulations so that the EPA could correct an error in these provisions that came to the EPA’s attention after the court challenge was filed.

The EPA released draft guidance (EPA draft guidance for PM 2.5 modeling) for PM 2.5 modeling which
ref lects EPA's preliminary recommendations for how a stationary source seeking a PSD permit may

demonstrate that it will not cause or contribute to a violation of the NAAQS and PSD increments for

PM 2.5 , as required under Section 165(a)(3) of the CAA and 40 CF R 51.166(k) and 40 CFR 52.21 (k).
The dra ft Guidance for PM 2.5 permit m odeling incorporates the modeling procedures and

recommendations from the March 23 , 2010 , guidance memorandum "Modeling Procedures for Demonstrating Compliance with PM 2.5 NAAQS," and f urther clarifies procedures for adequately addressing primary and secondarily formed PM 2.5 in a NAAQS compliance demonstration under the PSD program . Due to lack of other final guidance, Anadarko proposes to model PM 2.5 emissions

consistent with the recom mendations prescribed in the draft guidance document.

Per EPA draft guidance for PM 2.5 modeling, “The vacated provisions of the regulations inadvertently restricted the discretion of permitting authorities to conduct or require more than a screening analy sis in some circumstances where the EPA had called for permitting authorities to consider

17 Based on U .S. EPA Memorandum from Stephen D. Page to Bill Harnett, et al. titled, “Modeling Procedures for Demonstrating Compliance with PM 2.5 NAAQS”. March 23, 2010.

18 73 FR 28321 and 75 FR 64864.

19 Sierra Club v. EPA, No. 10

- 1413 (D.C. Circuit), 2013 WL 216018.Anadarko 20 Trinity Consultants

whether additional analysis was needed to make the demonstration required by Section 165(a)(3) of the CAA. Due to the court decision, the EPA will not rely, and advi sed permitting authorities with State Implementation Plan (SIP) approved PSD programs not to rely, on the SMCs for PM 2.5 to exempt permit applicants from compiling preconstruction monitoring data for PM 2.5 in accordance with Sections 40 CFR 51.166(m) and 4 0 CFR 52.21(m). However, the EPA believes PSD permit applicants may continue to meet the preconstruction monitoring requirements in these regulations by using data from existing monitors that are determined by the applicable permitting authority to be

rep resentative of background conditions in the affected area. The court decision does not preclude the use of SILs for PM 2.5 , but requires that EPA correct the error in the SIL regulations for PM 2.5 at 40 CFR 51.166(k)(2) and 40 CFR 52.21(k)(2). In the inter im, the EPA believes permitting authorities may continue to apply SILs for PM 2.5 to support a PSD permitting decision, but permitting authorities
should take care to ensure that SILs are not used in a manner that is inconsistent with the requirements of Se ction 165(a)(3) of the CAA

... . ” 20

Per EPA draft guidance for PM 2.5 modeling

, “A ny permitting authority wishing to use a particular SIL value as a screening tool in a significant impact analysis should determine whether a substantial portion of the NAAQS h as already been consumed . Preconstruction monitoring data (or adequately representative onshore monitoring data from an existing onshore monitoring network) should be evaluated against the respective PM 2.5 NAAQS. If the difference between the NAAQS and t he

measured or representative PM 2.5 background in the area is greater than the applicable SIL value, then the EPA believes it would be sufficient in most cases for permitting authorities to conclude that a source with an impact below that SIL value will no t cause a new NAAQS violation ...”

Anadarko is proposing to subtract background PM 2.5 concentration s from the NAAQS standard s to assess whether a substantial portion of NAAQS has already been consumed. If the difference between the NAAQS standard and the background concentration is greater than the respective PM 2.5 SIL then Anadarko is proposing to compare modeled PM 2.5 concentrations against the respective

PM 2.5 SILs. Also, Anadarko proposes to address the impact of the secondary PM 2.5 formation qualitat ively. If t he mode led PM 2.5 concentration is equal or greater than the respective SIL s then

Anadarko will submit an addendum to this application for conducting the full impact analysis

.



## 3.2 A DDITIONAL 

## I MPACTS 

## A NALYSIS

PSD regulations require that three addit ional impact analyses be performed as part of a PSD permit action. The PSD application to be prepared for the proposed project will contain three additional impact analyses: 1) an analysis of the air quality impact projected for the area as a result of an y commercial, residential, and industrial growth associated with the proposed facility, 2) an analysis of the impairment to soils, vegetation, and animals that may occur as a result of the proposed facility, and 3) an analysis of impairment to visibility ( haze at distant Class I areas and plume impairment at sensitive Class II receptors) that may occur as a result of the proposed facility. This section of the protocol discusses the methodologies that will be followed in completing and presenting the
additi onal impacts analyses. Anadarko believes that the approach outlined will satisfy Anadarko ’s obligations in this regard for this project.

20 http://www.epa.gov/scram001/guidance/guide/Draft_Guidance_for_PM25_Permit_Modeling.pdf

.Anadarko 21 Trinity Consultants



### 3.2.1 G ROWTH 

### A NALYSIS

The purpose of the growth analysis is to quantify project

- associated growth; that is, to predict how much new growth is likely to occur in order to support the source under review, and then to estimate the air quality impacts from this growth either quantitatively or qualitatively. Typically, the amount of residential growth depends on the size of the a vailable work force, the number of new employees, and the availability of housing in the area. Associated commercial and industrial growth consists of new sources providing goods and services to the new employees and to the new industrial source

itself. Because of the seasonal and temporary nature of the proposed OCS source, Anadarko anticipates that any industrial, commercial and residential growth will be insignificant.



### 3.2.2 S OILS AND 

### V EGETATION 

### A NALYSIS

The EPA, through the CAA , has promulgated primary an d secondary ambient air quality standards. The primary air quality standards are set at levels necessary to provide an adequate margin of safety to protect human health. The secondary standards are set at levels to provide for protection of public

welfar e, where welfare is defined to include the following: soils, water, vegetation, manmade materials, animals, wildlife, weather, visibility, climate, and damage to or deterioration of property. 21

Table 3

- 1 shows the secondary NAAQS for each relevant regulate d air pollutant for this modeling analysis. To satisfy this requirement, Trinity will assess the modeling results against the secondary NAAQS, for determination of impacts to soil and vegetation. If ambient air concentrations are found
to be less than th e secondary NAAQS, it will be presumed that emissions from the proposed sources will not result in harmful effects to either soil or vegetation. 22 Alternatively, due to the location of the proposed exploration activities bei ng more than 100 km from the nea rest shoreline i f ambient air
concentrations are found to be less than the S IL s , it will be presumed that emissions from the proposed sources will not result in harmful effects to either soil or vegetation

.



### 3.2.3 V ISIBILITY 

### A NALYSIS

As per the U.S. EPA New Sourc e Review Workshop Manual , visibility impairment analysis should be performed for impacts that occur within the area affected by proposed project. 23 The EPA’s Workbook for Plume Visual Impact Screening and Analysis ( Workbook ) provides guidance for
conductin g a visibility impairments analysis through the use of VISCREEN, a plume visibility impact

model. 24 The methods in this workbook are designed for Class I area impacts; however, the procedures are generally applicable to other areas as well. The VISCREEN m odel is recommended for the first level (Level 1) screen. If predicted values from the VISCREEN model are greater than the standardized screening values, the emissions are judged to have the potential for visibility impairment.

21 Sections 109 and 302 of the Clean Air Act.

22 U.S. EPA, Off

ice of Air Quality Planning and Standards, New Source Review Workshop Manual , Research Triangle Park, NC, October 1990.

23 U.S. EPA, New Source Review Workshop Manual (Draft): Prevention of Significant Deterioration and Nonattainment Area Permitting , Octobe r 1990.

24 U.S. EPA Office of Air Quality Planning and Standards. Workbook for Plume Visual Impact Screening and Analysis . Research Triangle Park, NC. EPA

- 450/4

- 88

- 015.Anadarko 22 Trinity Consultants

If the potential for vi sibility impairment is indicated, the next level analysis, Level 2 analysis, is required. Although VISCREEN is primarily designed for assessing plume visual impacts in Class I areas, as noted in the Workbook for Plume Visual Impact Screening and Analysis, it can also be applied in PSD Class II areas. Default values will be used for background ozone (0.04 ppm), stability class (6), and wind speed (1 m/s). Per the workbook, distances from the emission source for the Class

II area evaluations can be specifi ed “arbitrarily.” The application of VISCREEN is limited to distances less than or equal to 50 km. Therefore to conservatively estimate the potential visual impact in the impact are a that is more than 50 km from the drilling location, the 50 km distance will be used in the VISCREEN analysis.Anadarko 23 Trinity Consultants 

## 4. C LASS 

## I A IR 

## Q UALITY 

## D ISPERSION 

## M ODELING 

## R EQUIREMENTS

Two principal air quality impacts are considered for Class I areas: PSD Increments for NO X , PM 2.5 , and PM 10 , and AQRV s . This section of the protocol describes t he procedural requirements for assessing the impacts of emissions from Anadarko ’s proposed drillship on Breton NWR, St. Marks NWR, and Bradwell Bay Wilderness areas.



## 4.1 C LASS 

## I A REA 

## PSD I NCREMENT

In general, all PSD permit applications are required to demonst rate through air quality modeling that the emissions increases from the proposed project will not cause or contribute to any violations of allowable increments within affected Class I areas, which are protected to a greater degree (i.e., the

allowable incr ements are lower) than Class II areas. A significant contribution to Class I Increment consumption is defined as a modeled concentration in excess of the significant impact levels (SILs)
summarized in Table 4

- 1, which were originally developed as part of the 1996 NSR reform rulemaking and have subsequently been adopted as informal modeling significance levels for Class I Area analyses that are used to determine if a project is likely to cause or contribute to a Class I area
Increment violation.

T ABLE 4

- 1

. C LASS I A REA PSD I NCREMENTS & M ODELING S IGNIFICANCE L EVELS

Pollutant Averaging Period Class I Increment
(  g/m 3 ) Significance Level

(  g/m 3 )

PM 10 24

- hour 8.0 0.32

Annual 4.0 0.16

PM 2.5 24

- hour 2 .0 0.07

Annual 1 .0 0.06

NO 2 [1 ] Annual 2.5 0.1

[1 ] On February 9, 2010, U.S. EPA Promulgated a NO 2 NAAQS for the 1

- hr averaging period. However, a NO 2 PSD
Increment standard for the 1

- hr averaging period was not established as part of this action. See 75 Fed. Reg. 6474, Primary National Ambient Air Quality Standards for Nitrogen Dioxide (February 9, 2010).

Since the proposed OCS source will have potential emissions of NO X, PM 2 .5 , and PM 10 in excess of the

P SD Significant Emission Rates (SERs), the Class I area PSD Increment analysis will be completed

for each of these pollutants

. 25

25 VISTAS, Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART)

, Revision3.2 , revised August 31, 2006. http://www.vistas

- sesarm.org/documents/BARTModelingProtocol_rev3.2_31Aug06.pdfAnadarko 24 Trinity Consultants

If the significance levels for NO X, PM 2.5 , and PM 10 are exceeded, a regional inventory will be developed and the impacts cause d by the OCS source and the regional inventory will be compared against the Class I Area Increments.



## 4.2 C LASS 

## I AQRV A NALYSES

The FLAG Phase I report provides the following definitions relating to AQRV: 26

Air Quality Related Value

- A resource, as identified by the FLM for one or more

Federal areas that may be adversely impacted by a change in air quality. The resource may include visibility or a specific scenic, cultural, physical, biological, ecological, or recreational resource identified by the FLM for a particular area.

Adverse Impact On Visibility

- Visibility impairment which interferes with the management, protection, preservation, or enjoyment of a visitor's visual experience of a

Federal Class I or Class II area. This determination must be made on a case

- by

- case basis taking into account the geographic extent, intensity, duration, frequency and time of visibility impairments, and how these factors correlate with (1) times of visitor use of the Class I area, and (2) the frequency and timing of natura l conditions that reduce visibility. This term does not include effects on integral vistas. [40 CFR §51.301(a)]

Adverse Impact on an AQRV

- An unacceptable effect, as identified by an FLM that results from current, or would result from predicted, deteri oration of air quality in a Federal Class I or Class II area. A determination of unacceptable effect shall be made

on a case

- by

- case basis for each area taking into account existing air quality conditions.
It should be based on a demonstration that the c urrent or predicted deterioration of air quality will cause or contribute to a diminishment of the area's national significance, impairment of the structure and functioning of the area's ecosystem, or impairment of the quality of the visitor experience in the area.

AQRV indicators typically identified by FLM include nitrogen deposition, sulfur deposition, and visibility degradation . Based on discussion with FWS, Anadarko is required to perform AQRV analyses for all three indicators mentioned above for Bre ton and St. Marks Class I areas. 27 Based on guidance received from FS, the AQRV analysis for Bradwell Bay is required to be performed for nitrogen deposition, sulfur deposition, and ozone. An AQRV analysis for visibility at Bradwell Bay is not required. 28

26 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Division, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 2010.

27 Based on Personal Communication, Phone conversation between Ms. Jill Webster (FWS) and and Mr. Rahul Pendse (Trinity) on October 12, 2012; E

- mail from Ms. Jill Webster (FWS) to Mr. Dhesikan Venkatesan (Trinity) sent on October 10, 2012; and Phone conversation betwe en Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18,
2012.

28 Based on Personal Communication, Phone conversation Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012, visibility has not been established as an AQ RV for Bradwell Bay.Anadarko 25 Trinity Consultants



### 4.2.1 D EPOSITION

In the deposition analysis, the contribution of Anadarko ’s proposed drilling operations to the deposition of chemical species in the Class I area will be evaluated against the deposition assessment threshold (DAT) values for sulfate and nitra te set by the FLM. The DAT represents “ the additional amount of N or S deposition within a Class I area, below which estimated impacts from a proposed new or modified source are considered insignificant .” The threshold is not necessarily an adverse impac t threshold and coastal ecosystems have evolved under naturally higher sulfur deposition rates. FLM guidance for assessment of deposition impacts suggests that an appropriate sulfur and nitrogen DAT is 0.005 kg/ha/yr and 0.01 kg/ha/yr respectively, for al l Class I areas in the Eastern United

States. 29 The procedures specified in the FLAG Phase I r eport (revised 2010) will be used to model nitrogen and sulfur deposition. 30 For sulfur, both wet and dry fluxes of SO 2 and sulfates (SO 4 ) will be modeled. The su m of wet and dry deposition fluxes for SO 2 and SO 4 represents the total sulfur deposition as shown in Equation 3

.

Equation 3

For nitrogen, the dry flux for NO
x , and wet and dry deposition fluxes for nitrates (NO 3 ), nitric acid (HN O 3 ), and ammonium ion (NH 4 ) from ammonium nitrate (NH 4 NO 3 ) and ammonium sulfate (NH 4 ) 2 SO 4 ) will be modeled. Therefore, the sum of dry flux for NO
x and wet and dry deposition fluxes for NO 3 , HNO 3 , and ammonium ion (NH 4 ) from
ammonium nitrate and sulfate re presents the total nitrogen de position, as shown in Equation 4

.

Equation 4

In accordance with the FLAG Phase I report (revised 2010) , gas phase deposition will be
modeled for SO 2 , NO
x , and HNO 3 , and particle phase deposition will be modeled for SO 4 and NO 3 . The contribution of the proposed project to the deposition of nitrogen and sulfur species in each Class I area will be estimated and assessed against the appropriate DAT in the modeling report.

29 U.S. National Park Service (NPS)

- Air Resources Division and U.S. Fish and Wildlife Service

- Air Quality Branch, Interagency Guidance on Nitrogen and Sulfur Deposition Analyses , accessed on November, 2011 via NPS website

-
www.natu re.nps.gov/air/Pubs/pdf/flag/nsDATGuidance.pdf.

30 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Division, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Relat ed Values Workgroup (FLAG)

-- Revised, 2010

.Anadarko 26 Trinity Consultants



### 4.2.2 V ISIBILITY

Visibility can be af

fected by plume impairment (heterogeneous) or regional haze (homogeneous). Plume impairment results when there is a contrast or color difference between the plume and a viewed background (the sky or a terrain feature). Plume impairment is generally only of concern when the Class I area is near the proposed source (i.e., less than 50 km). Since the distance between the proposed OCS source and the
nearest Class I area evaluated is greater than 50 km, only regional haze will be considered in this analysis.

Regional haze occurs at distances where the plume has become evenly dispersed into the atmosphere such that there is no definable plume. The primary causes of regional haze are sulfates (SO 4 ) and nitrates (NO 3 ) (primarily as ammonium salts), which are fo rmed from
emissions of SO 2 and NO X through chemical reactions in the atmosphere. These reactions take time, hence distance. Near the emissions source little NO X or SO 2 will have formed nitrate or sulfate, whereas far from a source nearly all SO 2 will hav e formed sulfate and

most NO X will have formed nitrate. Particulate emissions also contribute to regional haze but to a lesser extent since sulfates and nitrates are hygroscopic species that increasingly reduce visibility with increased relative humidity.

Regional haze is measured using the light extinction coefficient ( b ext ). To determine a change in regional haze, the percentage change of the light extinction coefficient (  b ext )
will be evaluated as s hown in the following Equation 5 :

Equation 5

The Δb ext value attributable to a single facility that is generally acceptable to the FLM is
5% on a 24

- hour average basis. There are a number of available m ethods that can be used to estimate the percentage change of light extinction coefficient associated with an emissions source. The peak 24

- hour average visibility impairment as predicted by the air quality model is one conservative measure used to attribu te visibility affects to a single source. However, as stated in the preamble of the U.S. EPA’s Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, the CALPUFF model uses a simplified chemistry that “...tend s to magnify the actual visibility
effects” of a source. 31 Therefore, the U.S EPA recommends the consideration of the 98 th percentile of modeled visibility values to assess visibility impacts, and states in the preamble, “...we believe it is appropriate to use the 98th percentile

— a more robust approach that does not give undue weight to the extreme tail of the distribution. The use of
the 98 th percentile of modeled visibility values would appear to exclude roughly 7 days per year from consideration. In our judgment, this approach will effectively capture the sources that contribute to visibility impairment in a Class I area, while minimizing the likelihood that the highest modeled visibility impacts might be caused by unusual

31 U.S EPA, Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, July 6, 2005.Anadarko 27 Trinity Consultants meteorology or conservative ass umptions in the model.” The use of the 98th percentile approach has also been formalized in the FLAG Phase I r eport ( revised 2010)

.

In the revised FLAG Phase I r eport ( revised 2010), FLAG has proposed a new algorithm for calculating the background extinc tion coefficient based on the revised method in the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. IMPROVE protocols for reconstructing ambient light extinction from measured aerosol species are used in evaluating compliance u nder the Regional Haze Rule (RHR) and also are relied on for conducting Class I area AQRV analyses. The algorithm based on the IMPROVE protocols is recommended as the regulatory default background extinction calculation methodology by the FLAG Phase I r ep ort ( revised 2010)

, and so Trinity shall

use the se procedures to calculate the background extinction coefficient, as explained
below.

October 2010 FLAG Phase I Revised Report

– Calpost “Method 8”

In CALPOST “Method 8”,  b ext is computed using a monthl y average relative humidity adjustment particular to each Class I area, applied to background and modeled concentrations of large and small sulfates and nitrates, and sea salt. Because a monthly average is used, no cap on f (RH) is necessary and the result s tend to be smoothed, since peak short

- term humidity events are not considered.

Procedures specified in the FLAG Phase I r eport ( revised 2010) will be used to determine the background extinction using “Method 8”. The background extinction coefficient
b ext,background is calculated using the IMPROVE equation for calculating light extinction, as shown in Equation 6 obtained from Figure 5 of the FLAG Phase I r eport ( revised 2010) : 32

b ext, background = 2.2 × f S (RH) × [Small Sulfate] + 4.8 × f L (RH) × [Large Sulfate]

+ 2.4 × f

S (RH) × [Small Nitrate] + 5.1 × f L (RH) × [Large Nitrate]

+ 2.8 × [Small Organic Mass] + 6.1 × [Large Organic Mass]

+ 10 × [Elemental Carbon] + 1 × [Fine Soil] + 0.6 × [Coarse Mass]

+ 1.7 × f

SS (RH) × [Sea Salt] + Rayleigh Scattering (Site Specific)

+ 0.1755 × [NO 2 ] Equation 6

where:

[ ] indicates concentrations in μg/m 3

f S (RH) = Relative humidity adjustment factor for small sulfate and nitrate

f L (RH) = Relative humidity adjustment factor for large sulfate and nitrate

f SS (RH) = Relative humidity adjustment factor for sea salt

32 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Di vision, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 2010.Anadarko 28 Trinity Consultants Mont hly average f L (RH), f

S (RH) and f

SS (RH) values for Breton NWR and St. Marks are

shown in Table 4

- 2 and Table 4

- 3 , as obtained from Tables 7, 8, and 9 respectively of the

FLAG Phase I r eport ( revised 2010)

.

T ABLE 4

- 2

. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR B RETON NWR

Month Average f s (RH) Average f L (RH) Average f ss (RH)
January 4.08 2.91 4.10 February 3.82 2.76 3.89

March 3.79 2.74 3.87 April 3.74 2.72 3.85
May 3 .94 2.83 4.02

June 4.12 2.94 4.21 July 4.41 3.10 4.44
August 4.37 3.07 4.38 September 4.18 2.97 4.23

October 3.92 2.82 3.99

November 3.93 2.83 4.01

December 4.06 2.90 4.11Anadarko 29 Trinity Consultants T ABLE 4

- 3

. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR S T

. M ARKS

Month Average f s (RH) Average f L (RH) Average f ss (RH)
January 4.24 2.98 4.18 February 3.89 2.78 3.89

March 3.79 2.73 3.82 April 3.72 2.69 3.76
May 3.79 2.74 3.85

June 4.32 3.04 4.30 July 4.56 3.17 4.49 August 4.63 3.21 4.54 September 4.43 3.1 4.39

October 4.19 2.96 4.19

November 4.16 2.94 4.15

December 4.39 3.06 4.30

Additionally, the most recent values for the annual average background concentrations at

Breton and St. Marks obtained from Table 6 of the FLAG P h ase I r eport ( revised 2010) are provided in Table 4

- 4. 33 These values will be used to calculate background extinction.

T ABLE 4

- 4

. A NNUAL A VERAGE B ACKGROUND V ALUES FOR B RETON & S T

. M ARKS

Species Breton (  g/m 3 ) St. Marks
(  g/m 3 )

Ammonium Sulfate 0.23 0.23

Ammonium Nitrate 0.10 0.10 Organic Carbon Mass 1.78 1.80

Elemental Carbon 0.02 0.02

Soil 0.48 0.50

Coarse Mass 3.01 3.00

Sea Salt 0.19 0.10 Rayleigh Scattering 11 Mm

- 1 11 Mm

- 1

The me thodology presented in Figure 5 of the FLAG Phase I r eport ( revised 2010) will be used to calculate large and small nitrates, large and small sulfates, and large and small organic mass.

33 U.S. Forest Service

– Air Quality Program, National Park Service

– Air Resources Divisio n, U.S. Fish and
Wildlife Service

– Air Quality Branch , Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 2010

.Anadarko 30 Trinity Consultants The extinction coefficient attributable to emissions increases from t he proposed project

b ext,project will also calculated. The extinction resulting from the project is calculated as shown in Equation 7 34 :

b ext, project = 2.2 × f S (RH) × [Small Sulfate] + 4.8 × f L (RH) × [Large Sulfate]

+ 2.4 × f

S (RH) × [Small Nitrate] + 5.1 × f L (RH) × [Large Nitrate]

+ 2.8 × [Small Organic Mass] + 6.1 × [Large Organic Mass] + 1 × [Fine Soil]

+ 0.6 × [Coarse Mass] + 0.1755 × [NO 2 ]
Equation 7

where:

[ ] indicates concentrations in μg/m 3

f S (RH) = Relative humidity adjustment factor for small sulfate and nitrate

f L (RH) = Relative humidity adjustment factor for large sulfate and nitrate

The 98 th percentile Δb ext percentage change results using “Meth od 8” will be calculated and presented in the modeling report.



### 4.2.3 O ZONE

Ozone is a toxic air pollutant that is formed on warm, sunny days when its precursors NO and VOC react in the presence of sunlight. Because ozone is a regional pollutant,

precursor sourc es both near and far from Class I areas can contribute to ozone formation. However, due to the complex photochemical reactions that are involved in the formation of ozone, it is difficult to quantify specific relationships between precursor emissions and ambient ozone concentrations at a Class I area, and also to quantify the specific relationship between ambient ozone at a Class I area and vegetation response. Therefore, FLAG has chosen to focus on the effects of ozone on vegetation and the levels of ozo ne generally known to be phytotoxic in Class I areas as indicators of concern regarding ozone impacts on AQRVs. Based on previous discussions with FS for similar EGOM projects
Anadarko will address the impacts of ozone exposure as a result of the proposed drilling operations on veget ation at Bradwell Bay. 35

Based on review of available dispersion models and discussion with FS, it has been found that there are currently no dispersion models available that can relate emissions from a single source to changes in ozone concentrations at particular receptor locations. However, as previously discussed with FS, since single source attribution modeling is possible for both visibility and deposition, Trinity proposes to demonstrate compliance with the

34 Equation 7 has been obtained based on Equation 6 except that there will be no project extinct ions due to EC and sea salt, since no elemental carbon or sea salt will be emitted from the proposed project, as described in Section 2 of the
report.

35 Based on Personal Communication, Phone conversation between Ms. Melanie Pitrolo (FS) to Mr. Rahul Pen dse (Trinity) on October 18, 2012.Anadarko 31 Trinity Consultants deposition th resholds at Bradwell Bay as a method of addressing impacts of ozone on the vegetation at Bradwell Bay. 36

Demonstrating compliance with the deposition thresholds shall provide an indication of whether the proposed project operations NO X emissions are likely to cause an adverse impact on soils, and/or surface waters. If the results of deposition modeling are below the DATs, it shall demonstrate that the project’s NO X emissions do not cause any adverse impacts on soils and/or surface water, and since all FLM areas are assumed to be NO X limited for formation of ozone, it can be deduced that there are no ozone impacts on the vegetation at Bradwell Bay. 37 It should also be noted that if the PSD Class I area modeling analysis demonstrates that Class I area SILs ar e not exceeded for NO 2 , then that would provide additional demonstration that no significant impact on ozone levels at Bradwell Bay would occur.

If the results of the deposition modeling exceed DATs, then Trinity shall consult with FS to determine the pro cedures for conducting an analysis for assessing impacts of ozone exposure on the vegetation at Bradwell Bay. Consistent with the methodology used in the similar OCS applications submitted to EPA in the past, a monitoring station in Sumatra,
Florida will be assumed to be a representative monitoring station for obtaining the ambient ozone monitoring data for years 2001 through 2003 respectively . This data will be provided in the final modeling report

.

36 Based on Personal Communication, Phone conversation between Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012. Per discussion with Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity),
vis ibility has not been established as an AQRV for Bradwell Bay.

37 Per Section 3.4.5 of Phase I Report of the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG)

-- Revised, 2010

.Anadarko 32 Trinity Consultants 

## 5. M ODEL ING 

## M ETHODOLOGY AND 

## I NPUTS

This section of the modeling report describes the modeling procedures and data resources utilized in

the Class I and Class II Area air quality modeling analyses.



## 5.1 M ODEL 

## S ELECTION

Dispersion models predict downwind pollutant concentrations by simulating the evolution of the pol lutant plume over time and space given data inputs . These data inputs include the quantity of emissions and the initial conditions of the stack exhaust to the atmosphere. According to the
Guideline , the extent to which a specific air quality model is sui table for the evaluation of source impacts depends on (1) the meteorological and topographical complexities of the area; (2) the level of detail and accuracy needed in the analysis; (3) the technical competence of those undertaking such simulation modeling ; (4) the resources available; and (5) the accuracy of the database (i.e., emissions inventory, meteorological, and air quality data).

The preferred model for analyzing long

- range pollutant transport (i.e., distances greater than 50 km)
is the CALPUFF m odeling system. The EPA

- approved version (Version 5.8) of the CALPUFF model will be used to determine the possible impacts of the proposed project

. The post

- processing of the CALPUFF data will be performed using the recently EPA

- approved version (Version 6.221) of
the CALPOST. 38

CALPUFF is a multi

- layer, multi

- species, non

- steady

- state Lagrangian puff model, which can
simulate the effects of time

- and space

- varying meteorological conditions on pollutant transport, transformation, and removal. For this r efined analysis, meteorological fields generated by CALMET will be used as inputs to the CALPUFF model to ensure that the effects of terrain and spatially varying surface characteristics on meteorology are considered.

In addition to meteorological data, t he CALPUFF model uses several other input files to specify source and receptor parameters. The selection and control of CALPUFF options are determined by

user

- specific inputs contained in the control file. This file contains all of the necessary informat ion to define a model run (e.g., starting date, run length, grid specifications, technical options, output options). The air quality modeling will be performed using CALPUFF default options unless otherwise noted, as specified in the federal Guideline

, th e applicable guidance memorandum from Support Center for Atmospheric Modeling (SCRAM) website, FLAG Phase I Report

- revised ( October 2010), and IWAQM documents. The EPA approved default options do not include the deposition and chemistry components of th e CALPUFF model; hence, these options will not be used while estimating concentrations for comparison against the EPA established significance thresholds.

The following sections describe the modeling domain, meteorological data, background

concentration s, and model implementation to be used for the analysis of the proposed Anadarko drilling operations.

38 http://www.epa.gov/ttn/scram/dispersion_prefrec.htm#calpuff

.Anadarko 33 Trinity Consultants 

## 5.2 M ODEL 

## D OMAINS

The Class I and Class II modeling analysis will be performed in the Lambert Conformal Conic (LCC) coordinate system based on the design of t he VISTAS Regional Haze Rule (RHR) modeling, with standard parallels of 33o N and 45o N latitude, and reference latitude and longitude of 40o N and 97o W respectively

. 39 VISTAS RHR Model Domain 2 will be utilized as the CALMET meteorological
domain. 40 The different VISTAS RHR Model Domains are shown below in Figure 5

- 1.

F IGURE 5

- 1

. V ISTAS RHR M ODEL D OMAINS

The CALPUFF computational domain will be chosen as a subset of the CALM ET meteorological domain such that it encompasses both the OCS source and all receptors in the Class I and Class II areas, with ample area beyond all receptors (50 km) to allow for the possible recirculation of puffs. The grid resolution for the domain wi ll be 4 km.

39 V ISTAS, Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART) , December 22, 2005, revised August 31, 2006.

40 Phone conversation between Ms. Jill Webster (FLM, Breton NWR) and Mr. Rahul Pendse (Trinity) o n October 12, 2012; and Email from Ms. Jill Webster (FWS) and Mr. Dhesikan Venkatesan (Trinity) sent on October 10,
2012.Anadarko 34 Trinity Consultants T ABLE 5

- 1. V ERTICAL G RID S TRUCTURE

Vertical Grid Cell Cell Face Height
(meters)

1 20

2 40

3 80

4 160

5 320

6 640

7 1,200

8 2,000

9 3,000

10 4,000

Vertical grid structure is defined by the cell face height. The cell fa ce height of each cell indicates its vertical extent. The vertical domain will be composed of terrain

- following grid cells, the number and size of which are chosen so as to constrain the boundary layer in which dispersion and chemical
transformations take place. Based on information available in the VISTAS RHR Modeling Protocol, and the IWAQM guidance document, the vertical grid structure selected for this analysis is presented
above in Table 5

- 1

. 41 CALMET and CALPUFF will use the same cell face heights.



## 5.3 R EPRESENTATION OF 

## M ODELED 

## S OURCES

Anadarko proposes to model the PM 2.5 , PM 10 , CO, and NO 2 emissions from the proposed OCS source assuming that all emissions would be emitted through a single stack which would be representative of the expected impacts . The stack will be modeled with worst

- case coordinates, with the drillship assumed to be located at the closest point in the lease block within the “wedge” to the nearest Class I

and Class II area. For Breton, the worst

- case location shall be the NW corner of the worst

- case lease block. For St. Marks and Bradwell Bay, the NE corner of the worst

- case lease blocks shall be

considered as the worst

- case location

.

For purposes of the Class I and Class II modeling analysis, all emissions from the drillship will be modeled as a single point source with the emissions emitted through a single stack

. T he worst

- case support vessels emissions will be modeled as one point source

. The point source representing the support vessels will be placed on the straight line con necting the drillship location and the nearest
receptor location at 25 nautical mile s from the drillship location

.

41 VISTAS, Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART) , December 22, 20 05, revised August 31, 2006, and the U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long

- Range Transport Impacts , Research Triangle Park, North Carolina, EPA

- 454/R

95

- 006, December 1998.Anadarko 35 Trinity Consultants

Additionally, the stack parameters for the stack representing drillship emissions will be based on the stacks associated with the main eng ines on the drillship, w hich are the largest sources of PM 2.5 , PM 10, CO, SO 2 , and NO 2 emissions. Similarly, the stack parameters for the stack representing the support
vessels emissions will be based on the stack parameters for the highest emitting engine s. The stack height will represent the height above the sea level (water line) to the main engine stack. A summary
of the modeling parameters, source parameters and emission rates used in the modeling analysis shall be provided with the final modeling re port.



## 5.4 R ECEPTOR 

## L OCATIONS FOR 

## C LASS 

## I A REAS

The National Park Service (NPS) Air Resources Division (ARD) has developed a database of modeling receptors for all of the Class I areas in the United States. 42 The database provides the location (lat/long, dd) coordinates and elevation information for receptors for each Class I area. Receptor locations obtained from the database for each Class I area shall be were converted to the LCC coordinate system using appropriate conversion factors and will be used in th ese Class I analyses.



## 5.5 R ECEPTOR 

## L OCATIONS FOR 

## C LASS 

## II A REAS

The seaward boundaries and Air Quality Control Regions for Louisiana, Mississippi and Alabama

extend for three nautical miles offshore and for nine nautical miles offshore Florida. For Anadarko ’s Class II modeling analysis, discrete receptors were located 25 nautical miles from the se a ward boundaries of Louisiana, Mississippi, Alabama and Florida. The receptors were placed at 1

- km intervals as per Guidance received from EPA region 4 . The actual sets of receptors used in Class II analysis were provided by EPA Region 4

. 43 Because all of these receptors are over water, terrain elevations were assigned an elevation of 0 m (i.e., sea level) for Class II impact analysis. If t he NAAQS and PSD Increment analyses is required , an addendum to this protocol will be submitted to the EPA Region 4 for approval

.



## 5.6 E MISSIONS 

## S PECIATION

Modeling of visibility impairment due to PM emissions requires that the components of the exhaust stream be speciated because diff erent size and phases of particulate matter affect visibility to varying extents. The amount by which a mass of a certain species scatters or absorbs light is termed the extinction efficiency or coefficient, and varies considerably from coarse particulate matter to
elemental carbon.

Anadarko proposes to estimate speciated PM emissions associated with the proposed project based on

AP

- 42 emission factors and conservative engineering estimates. Emission sources used for the proposed drilling project will primarily comprise of large diesel fired engines. Although the drillship

will also have a few small diesel

- fired engines, the large diesel

- fired engines will contribute the majority of the emissions from the proposed drilling operations. Therefore, Anada rko proposes the use of particle size

- specific emission factors for large diesel fired engines from AP

- 42, Table 3.4

- 2,

42 http://www.nature.nps.gov/air/maps/recepto rs/index.cfm

43 Based on Personal Communication, E

- mail from Mr. Stan Krivo (EPA Region 4 ) and Mr. Rahul Pendse (Trinity) on October 1, 2012.Anadarko 36 Trinity Consultants

Particulate and Particle

- sizing Emission Factors for Large Uncontrolled Stationary Diesel Engines (October 1996) to determine PM speciat ion for emissions from the drillship.



## 5.7 T ERRAIN 

## P ROCESSING FOR 

## C LASS 

## II A NALYSIS

As the proposed OCS source is located in the GOM and corresponding Class II receptors will be placed 25 miles away from respective state seaward boundary , the entire modeling do main will be located completely over water in the Gulf of Mexico. Therefore, all modeled sources and Class II receptors are assumed to be situated at sea level and the elevations for off

- property sources and receptors will be set to zero for the Class II modeling analysis.



## 5.8 B UILDING 

## D OWNWASH

Building downwash accounts for the effects of nearby structures on the flow of emissions from their respective release structures. However, building downwash effects were not included in the modeling as they will not significantly affect concentrations when the nearest receptors are located more than
50 km from the worst

- case drillship location. Hence, d ue to the relatively large distance of the proposed drillship from the Class I and Class II area, building downwash will not be enabled. 44



## 5.9 B ACKGROUND 

## C ONCENTRATIONS

As described in the Section 3

- 1.3, a background concentration of PM 2.5 will be required for assessing validity of use of PM 2.5 SIL. Since there are no monitors at the Inner OCS and Outer OCS boundary (i.e ., 25 nautical miles from the nearest state seaward boundary), a representative onshore background

concentration will be used per discussions with EPA Region 4. 45



## 5.10 CALMET (M ETEOROLOGICAL 

## D ATA 

## ) P ROCESSING

CALMET is the meteorological preprocessor that compile s meteorological data from raw observations of surface and upper air conditions, precipitation measurements, mesoscale model output, and geophysical parameters into a single hourly, gridded data set for input to CALPUFF.
Based on the previous guidance rec eived from the FLM and EPA Region 4 , three years of mesoscale meteorological (MM) data in the form of CALPUFF

- ready meteorological files developed by the
VISTAS for the period 2001

- 2003 (for VISTAS Domain 2) obtained from the Florida Department of
Environm ental Protection (DEP) will be used in this analysis. 46 N o additional meteorological data processing is expected for this analysis. In lieu of recent discussions with EPA Region 4 instead of the five year meteorological data, the three year meteorological dataset (2001

- 2003) developed by the VISTAS will be used for the PSD Class II impact assessments.

44 Per guidance provided on Pg. 45 of the VISTAS, Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART) , December 22, 2005, revised August 31, 2006.

45 Based on Personal Communication : Phone conversation among Mr. Stan Krivo (EPA Region 4) , Ms. Sara Carlson (Anadarko), and Mr. Rahul Pendse (Trinity) on July 9 , 201 3

.

46 Based on Personal Communication; Phone conversation between Ms. Jill Webster (FLM, Breton NWR) and Mr. Rahul Pendse (Trinity) on October 12, 2012, and Phone conversation between Mr. Stan Krivo (EPA Region 4 ) and Mr. Rahul Pendse (Trinity) on October 10, 2 012; and Email from Ms. Jill Webster (FWS) and Mr. Dhesikan Venkatesan (Trinity) sent on October 10, 2012. The meteorological data was obtained from Mr. Tom Rogers, Florida DEP, based on instructions from EPA Region 4

.Anadarko 37 Trinity Consultants 

## 5.11 CALPUFF P ROCESSING

Using the data provided by CALMET, CALPUFF simulates the dispersion, deposition, and chemical transformation of discrete puffs of mass fro m emission sources. Each puff contains emissions of

NO X , SO 2 , CO, PM 2.5 , and PM 10 and is transported throughout the domain while deposition and chemical transformation processes take place. CALPUFF is a Lagrangian puff model, the principle advantages of which are that pollutant plumes can evolve dynamically and chemically over time and can respond to complex winds caused by terrain effects, stagnation, or recirculation.

Emissions data and stack parameters will be entered into CALPUFF as previously desc ribed under

S ection 5 .3 of this protocol. Due to the relatively large distance of the proposed drillship from the

Class I and Class II area, building downwash will not be enabled. 47

This analysis will be performed with the deposition and chemical trans formation algorithms enabled for Class I AQRV analysis and disabled for the PSD Class I and Class II modeling analysis. A full resistance model is provided in CALPUFF for the computation of dry deposition rates of gases and particulate matter as a functio n of geophysical parameters, meteorological conditions, and pollutant species. An empirical scavenging coefficient approach using default options will be enabled in CALPUFF to compute the depletion and wet deposition fluxes due to precipitation scavenging

.

The CALPUFF model is capable of simulating linear chemical transformation effects by using pseudo

- first

- order chemical reaction mechanisms for the conversions of SO 2 to SO 4 , and NO X , which consists of nitrogen oxide (NO) and nitrogen dioxide ( NO 2 ), to N O 3 and HNO 3 . In this study, chemical transformations involving five species (SO 2 , SO 4 , NO X , HNO 3 , and NO 3 ) will be modeled using the MESOPUFF II chemical transformation scheme, per IWAQM guidance. 48 There are two

user

- selected input parameters that affect the MESOPUFF II chemical transformation, ammonia concentrations and ozone concentrations. The selection of each parameter is discussed separately.



### 5.11.1 O ZONE

Ambient ozone concentrations can be input to the model as a background level or using hourly, spatial ly varying observations. For this analysis, Anadarko proposes the use of data from the monitor at Sumatra, Florida (code

- SUM 156) . The proposed monitoring station is one of the closest monitoring stations from the modeling domain . Also, this

station h as all required meteorological data available . Information on the monitoring
station can be obtained from the CASTNET website. 49 Based on previous guidance

received from F LM and EPA region 4 , the ozone background level for the analysis will be

set at 80 ppb

.

47 Per guidance provided on Pg. 45 of the VISTAS, Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit Technology (BART) , December 22, 2005, revised August 31, 2006.

48 U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long

- Range Transport Impacts , Research Triangle Park, North Carolina, EPA

- 454/R

- 95

- 006, December 1998.

49 Information on the site monitor is available at www.epa.gov/castnet/sites/sum156.html . Information on ozone
data available at EPA’s CASNET website

– www.epa.gov/casnet/data.htmlAnadarko 38 Trinity Consultants



### 5.11.2 A MMONIA

IWAQM Phase 2 recommends the use of spatially constant background ammonia concentrations to participate in the MESOPUFF

- II chemical transformation mechanism. 50
In the absence of an extensive monitoring network for ammonia and due to the limita tion of CALPUFF to simulate only a single, domain

- average background ammonia level for each month of analysis, a single value will be used. The IWAQM guidance recommends the ammonia value be set between 0.5 parts per billion (ppb) for forested areas and 1 0 ppb for grasslands. Based on previous guidance received from FWS, the ammonia background level for the analysis will be set at 3 ppb. 51



### 5.11.3 CALPUFF P ROCESSING 

### C ONTROL

CALPUFF modeling will be conducted generally using the recommended regulatory default optio ns specified in Appendix B of the IWAQM guidance. The integrated puff representation will be used and puff splitting will be conservatively disabled.



## 5.12 CALPOST P OSTPROCESSING 

## A NALYSIS

The CALPOST postprocessor will be used to compute the ambient concentrati ons of CO, PM 2.5 , PM 10 , SO 2 , and NO 2 at Class I and Class II areas for assessment against the PSD Class I Increment modeling significance levels and PSD Class I I modeling levels , the total deposition of sulfur and nitrogen within each Class I area for asse ssment against the DAT, and the 98 th percentile of modeled visibility values 24

- hour average change in light extinction using Methods 8.

For PM 10 assessment against the PSD Class I and Class II significance levels, POSTUTIL will first be

used to combine t he speciated PM (PMC, PMF, and SOA) to calculate total PM 10 concentration. The

PM 10 concentration will then be processed using CALPOST and compared to the appropriate Class I
and Class II SILs. Similar methodology will be utilize for PM 2.5 post processin g. The secondary

PM 2.5 impacts will be addressed qualitatively.

For estimating the extent of nitrogen and sulfur deposition, POSTUTIL will first be used to combine the appropriate wet and dry fluxes of nitrogen

- and sulfur

- bearing species deposited as pa rticles and gases. These combined fluxes will then be processed using CALPOST to obtain the nitrogen and sulfur deposition values.

To determine the extent of change in light extinction from the proposed project, the Ammonia Limiting Method (ALM) will f irst be used to repartition the nitrate mass and recompute HNO 3 and

NO 3 concentrations. This methodology estimates the amount of ammonia available for the formation of ammonium nitrates after the preferential consumption of ammonia from the formation of

a mmonium sulfates. The ALM will be applied based on guidance provided in the VISTAS BART

50 U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long

- Range Transport Impacts

, Research Triang le Park, North Carolina, EPA

- 454/R

- 95

- 006, December 1998.

51 Based on Personal Communication; Phone conversation between Ms. Jill Webster (FWS) and Mr. Rahul Pendse (Trinity) on October 12, 2012; and E

- mail from Ms. Jill Webster (FWS) to Mr. Dhesikan Venkat esan (Trinity) sent on October 10, 2012.Anadarko 39 Trinity Consultants

Modeling Protocol

. 52 Visibility change will then be computed using “Method 8”, and results will be reported for the 98 th percentile for “Method 8”, for each of the thr ee years of meteorological data

modeled.

52 VISTAS; Protocol for the Application of the CALPUFF Model for Analyses of Best Available Retrofit
Technologies (BART) . December 22, 2005.
http://www.vistas

- sesarm.org/documents/BARTModelingProtocol_rev3.2_31Aug06.pdf , accessed on March 24, 2010.Anadarko 40 Trinity Consultants 

## 6. M ODELING 

## R EPORT 

## C ONTENTS

A document that details the modeling methodology and summarizes the modeling results will be

submitted to the FLM, as well as U.S. EPA Region 4

. The air dispersion modeling report will inc lude the following information:

 Brief o verview of the proposed project ;  An area map indicating location of the source, receptors, model domain, and true north ;  Emission s rate summary for all proposed emission sources, with units consistent with modeling ;  S tack parameter summary for all proposed emission sources , with units consistent with modeling ;  Any calculations for stack parameters unless previously approved by U.S. EPA Region 4 ;  Approved modeling protocol ;  Technical basis for any nonstandard procedures ;  Summary of all model inputs (e.g., model used, met data, rural or urban dispersion coefficients, etc .) ;  Comparison of all modeling resu lts to the applicable standards ; and
 Electronic copies of all modeling files, including model input files, output files , met data with appropriate documentation if processing perform ed

.

If required, Anadarko will submit additional information to U.S. EPA Region 4 and FLM upon request.