## A IR 

## Q UALITY 

## D ISPERSION 

## M ODELING 

## P ROTOCOL



## A NADARKO 

## P ETROLEUM 

## C ORPORATION



## .  EGOM 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 ONSULTANTS
301 Main Street.
Suite 900 Baton Rouge, LA 70825 (225) 346-4003

May 2013

Project 131901.0020Anadarko Petroleum Corporation ii Trinity Consultants 

## T ABLE OF 

## C ONTENTS

1. I NTRODUCTION

...............................................................................................................  . 1
1.1 P ROJECT D ESCRIPTION

..................................................................................................... 

. 1
1.2 P ROJECT L OCATION

.........................................................................................................  2
1.3 D ESCRIPTION OF M ODELING P ROCEDURES ........................................................................ 4
1.4 C ONTENTS OF THE M ODELING P ROTOCOL ......................................................................... 5

2. S OURCE D ESCRIPTION ...................................................................................................... 6
2.1 D ESCRIPTION OF P ROPOSED OCS S OURCE ......................................................................... 6
2.2 E MISSION S OURCES ............................................................................................................. 7
2.3 P OTENTIAL E MISSIONS ........................................................................................................ 7
2.4 Q/D A NALYSIS .................................................................................................................... 7

3. C LASS II A IR Q UALITY D ISPERSION M ODELING R EQUIREMENTS ................................ 8
3.1 PSD S IGNIFICANCE A NALYSIS ............................................................................................ 9
3.1.1 S IGNIFICANT I MPACT A REA (SIA) ....................................................................... 12

3.1.2 P RE -C ONSTRUCTION M ONITORING A NALYSIS .................................................... 12
3.1.3 S PECIAL C ONSIDERATIONS FOR PM 2.5 ................................................................. 13
3.2 A DDITIONAL I MPACTS A NALYSIS ..................................................................................... 16
3.2.1 G ROWTH A NALYSIS ............................................................................................. 16
3.2.2 S OILS AND V EGETATION A NALYSIS .................................................................... 16
3.2.3 V ISIBILITY A NALYSIS .......................................................................................... 17

4. C LASS I A IR Q UALITY D ISPERSION M ODELING R EQUIREMENTS ................................ 18
4.1 C LASS I A REA PSD I NCREMENT ....................................................................................... 18
4.2 C LASS I AQRV A NALYSES ............................................................................................... 19
4.2.1 D EPOSITION .......................................................................................................... 20
4.2.2 V ISIBILITY ............................................................................................................ 21
4.2.3 O ZONE .................................................................................................................. 25

5. M ODELING M ETHODOLOGY AND I NPUTS ...................................................................... 27
5.1 M ODEL S ELECTION ........................................................................................................... 27
5.2 M ODEL D OMAINS .............................................................................................................. 27
5.3 R EPRESENTATION OF M ODELED S OURCES ....................................................................... 29
5.4 R ECEPTOR L OCATIONS FOR C LASS I A REAS ..................................................................... 30

5.5 R ECEPTOR L OCATIONS FOR C LASS II A REAS ................................................................... 30
5.6 E MISSIONS S PECIATION .................................................................................................... 30

5.7 T ERRAIN P ROCESSING FOR C LASS II A NALYSIS ............................................................... 31
5.8 B UILDING D OWNWASH ..................................................................................................... 31
5.9 B ACKGROUND C ONCENTRATIONS .................................................................................... 31
5.10 CALMET (M ETEOROLOGICAL D ATA ) P ROCESSING ........................................................ 31
5.11 CALPUFF P ROCESSING .................................................................................................... 32
5.11.1 O ZONE ................................................................................................................. 32
5.11.2 A MMONIA ............................................................................................................ 33
5.11.3 CALPUFF P ROCESSING C ONTROL ..................................................................... 33
5.12 CALPOST P OSTPROCESSING A NALYSIS .......................................................................... 33Anadarko Petroleum Corporation iii Trinity Consultants 6. M ODELING R EPORT C ONTENTS ..................................................................................... 35Anadarko Petroleum Corporation 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 ..2

T ABLE 3-1. A PPLICABLE PSD A IR Q UALITY L EVELS ............................................................................ 9

T ABLE 4-1. C LASS I A REA PSD I NCREMENTS & M ODELING S IGNIFICANCE L EVELS ......................... 18

T ABLE 4-2. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR B RETON NWR ........................................... 23

T ABLE 4-3. M ONTHLY F S (RH), F L (RH) AND F SS (RH) FOR S T

. M ARKS ................................................ 24

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

. M ARKS ........................ 24

T ABLE 5-1. V ERTICAL G RID S TRUCTURE ............................................................................................ 29Anadarko Petroleum Corporation v Trinity Consultants 

## L IST OF 

## F IGURES

F IGURE 1-1. A NADARKO ’ S EGOM E XPLORATORY P ROJECT L EASE B LOCKS IN E ASTERN G ULF OF
M EXICO

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

F IGURE 3-1. G ENERAL PSD M ODELING F LOWCHART ......................................................................... 11

F IGURE 5-1. V ISTAS RHR M ODEL D OMAINS ...................................................................................... 28Anadarko Petroleum Corporation 1 Trinity Consultants 

## 1. I NTRODUCTION



## 1.1 P ROJECT 

## D ESCRIPTION

Anadarko Petroleum Corporation (Anadarko) is a pplying 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 activities will consist of three phases – the initial drilling phase, a well completion phase and a maintenance operation phase. The proposed activities are planned to be conducted at various lease blocks within the “wedge” usi ng a dynamically positioned drillship and associated support vessels in the East ern Gulf of Mexico (EGOM), east of the 87.5 degree longitude. A map outlining the “wedge” in the Gulf of Mexico (GOM) identified by the boundary presented on the map located in Figure 1- 1. Within the wedge there are both active lease blocks (currently leased 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 longitude line to the west (Envir onmental 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

An OCS source is considered PSD major if pot ential emissions of any PSD-regulated pollutant exceed the major source thresholds of 250 tons pe r year (tpy) and the operations are considered a major source under the PSD program. The PSD prog ram 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 emissions 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 with an aerodynamic diameter less than 10 microns (PM 10 ), particulate matter with an aerodynamic diameter less than 2.5 microns (PM 2.5 ), nitrogen oxides (NO X ), sulfur dioxide (SO 2 ), carbon monoxide (CO), and volatile organic compounds (VOC). Accordingly, Anadarko is presently in the process of preparing a PSD permit application for submittal to U.S. EPA Region IV. As a part of the PSD application, an air qua lity modeling analysis will be presen ted 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 surroun ding area [i.e. impacts on soil and vegetation, visibility 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, a 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 hazeAnadarko Petroleum Corporation 2 Trinity Consultants and deposition. 1 In accordance with 40 CFR 52.21(p), “ the Federal Land Manager and the Federal official charged with direct responsibility for management of such lands have an affirmative responsibility to protect the air quality related valu es (including visibility) of such lands and to consider, in consultation with the Administrato r, whether 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 sour ces perform Class I modeli ng to demonstrate that the AQRVs of Class I areas are not adversely affected. This modeling protocol which includes the methodology Anadarko is proposing for both Class I and Class II modeling analyses have been prepared and is being provided for submittal to the FLM and U.S. EPA Region IV.



## 1.2 P ROJECT 

## L OCATION

Anadarko has identified all lease blocks currently av ailable for drilling operations in EGOM within the “wedge” and has determined which of these lease blocks are closest to all nearby Class I and
nearest state shoreline areas. Table 1-1 below provides the approximate distance of the worst-case (nearest) lease blocks within the “wedge” to where each Class I area is located relative to the lease block, the corresponding FLM for each Class I area, a nd 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 Shore line 141 NW 161

1 Anadarko’s Project lease blocks are located within three federally protected Class I areas in the Southern United
States.Anadarko Petroleum Corporation 3 Trinity Consultants F IGURE 1-1. A NADARKO ’ S EGOM E XPLORATORY P ROJECT L EASE B LOCKS IN E ASTERN G ULF

OF M EXICOAnadarko Petroleum Corporation 4 Trinity Consultants 

## 1.3 D ESCRIPTION OF 

## M ODELING 

## P ROCEDURES

On behalf of Anadarko, Trinity Consultants (Trini ty) is submitting this air quality modeling protocol to present U.S. EPA Region IV with a description of the proposed modeli ng procedures and data resources in advance of a PSD permit application, which will provide the results of all modeling analyses. The methodology described in the protoc ol will be further utilized in the final modeling report to demonstrate compliance with applicable st andards. Since the closest receptor for both Class I and Class II modeling is more than 50 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 CALPUFF air dispersion modeling system is cu rrently 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 th e applicable rules and requirements for dispersion modeling, including rules and guidance provided in U.S. EPA: Guideline on Air Quality Models , 40 CFR Part 51 - Appendix W (Revised, Nove mber 9, 2005) (referred to hereafter as Guideline ), the applicable guidance memorandum from Support Center for Atmospheric Modeling (SCRAM) website, the Draft New Source Review Workshop Manual 3 ,the Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report 4 , Reassessment of the Interagency Workgroup on Air Quality Modeling (IWAQM) Phase 2 Summary Report: Revisions to Phase 2 recommendations(Draft 2009 report) 5 , the Federal Land Managers’ Air Quality Related Values Workgroup (FLAG) Revised Phase I Report (FLAG 2010 report) 6 , the U.S. EPA’s Guidance for Estimating Natural Visibility Conditions under the Regional Haze Rule 7 , the U.S. EPA’s Regional Haze Regulations and Guidelines for Best Avail able Retrofit Technology (BART) Determinations 8

, previous communications between Trinity and EPA Region IV, 9 and previous communications between Trinity and the FLM for the three Class I areas. 10

.

2 40 CFR Part 51, Appendix A to Appe ndix 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-Range Transport Impacts , Research Triangle Park, North Ca rolina, 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 Caro lina, EPA-454/R-09-XXX, May 2009 Draft.

6 U.S. Forest Service – Air Quality Program, National Pa rk 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.

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 Personal Communication: Phone conversation between Mr. Stan Krivo (EPA Region IV) and Mr. Rahul Pendse (Trinity) on September 21, 2012.

10 Based on Personal Communication: Phone conversation between Ms. Jill Webster (FWS) and Mr. Rahul Pendse (Trinity) on October 12, 2012; E-mail from Ms. Jill Webster (F WS) to Mr. Dhesikan Venkatesa n (Trinity) sent on October 10, 2012; and Phone conversation betwee n Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012.Anadarko Petroleum Corporation 5 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 potential emissions, and a description of Q/d analysis;

 Section 3 describes the applicable modeling re quirements, which includes a discussion of the steps involved in a Class II Area modeling analysis;

 Section 4 describes the applicable modeling re quirements, which includes a discussion of the steps involved in a Class I Area modeling analysis;

 Section 5 describes the modeling methodology and inputs, which includes a discussion of the selected dispersion models, meteorological da ta, representation of sources, background concentrations, building downwash analysis, r eceptor locations, and other model inputs; and

 Section 6 describes the content of the modeling report that will be submitted to the FLM and U.S. EPA Region IV for review.Anadarko Petroleum Corporation 6 Trinity Consultants 

## 2. S OURCE 

## D ESCRIPTION



## 2.1 D ESCRIPTION OF 

## P ROPOSED 

## OCS S OURCE

The exploratory drilling activity will consist of three phases – the initial drilling phase, a well completion phase and a maintenance operation phase. Anadarko is requesting the flexibility to drill one or more wells in any of the lease blocks within the “wedge” while complying with any operational and emission limitations prescribed in th e air permits that will be issued. The proposed operations will be conducted using the drillships; Diamond Black Hawk (Black Hawk), Diamond Black Hornet (Black Hornet), and associated support vessels.

The Black Hawk and Black Hornet are dynamically-positioned drillships that are designed for operation in 12,000 feet of water. As a dynamically -positioned drillship, they maintain their position over the desired location by using the computer-cont rolled 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 Secti on 1, 40 CFR 55.2 states that a vessel shall only be
considered an OCS source when “ Permanently or temporarily atta ched to the seabed and erected thereon and used for the purpose of exploring, developing or producing resources therefrom...” Therefore, Black Hawk and Black Hornet does not qualify as an OCS source until the drillships are temporarily attached to the seabed during the proposed operations.

Anadarko will use the “worst-case” emission to dem onstrate compliance with the Class I Increments, NAAQS, Class II Increments and AQRVs threshold. This would give Anadarko the flexibility to drill and operate at any location within the worse-ca se lease block (nearest to respective Class I and state shoreline areas) or at any other location further away from a Class I and state shoreline area within the “wedge”. The major sources of em issions on the drillship as well as the support vessels will primarily consist of diesel-fired internal combustion engines and fuel storage tanks.

The associated support vessels will include a comb ination of supply boats (crew boats and work boats), anchor-handling boats, stimulation vessels, t ug and barge boats that will be used to transport personnel, supplies, and fuel to the drillship, as re quired, during the entire duration of the exploratory drilling. The anchor handling boat will act as a work boat or supply boat, but will not be used to set anchors while on site. As it is presently not know n which specific vessels will be available when the drilling commences, the support vessels will be used interchangeably dependin g upon availability. For purposes of the air permit applications and th e modeling analysis, suitable assumptions will be made to conservatively account for the worst-case emissions from the support vessels potentially available to support operations of the drillships. The emissions from support vessels will be considered for the modeling analysis while the support vessels are at the drillships, and while enroute to or from the drillships when within 25 miles of the drillships. Any such assumptions made for estimating the worst-case support vessel emissions will be appropriately documented in the final modeling report.

In addition to the boats, the support vessel fleet will also include a helicopter that will be used for transporting supplies and personnel. However, based on previous communications and discussionsAnadarko Petroleum Corporation 7 Trinity Consultants with U.S. EPA Region IV, the helicopter emissions (which are expected to be negligible) are not required to be considered for purposes of this PSD permitting effort. 11



## 2.2 E MISSION 

## S OURCES

The sources of emissions for Black Hawk and Black Hornet primarily consist of internal combustion engines, flares, painting operation, welding operation, dust collectors, mud-degassing, water blasting operation, a boiler, and fuel storage tanks. Fo r the support vessels, the emission sources includeinternal combustion engines and fuel storage tanks. The methodology used to determine the “worstcase” drillship emission modeled shall be provided in the application.



## 2.3 P OTENTIAL 

## E MISSIONS

As previously mentioned, the exploratory drillin g activity will consist of three phases – the initial drilling phase, a well completion phase and a maintenance operation phase. The well completion and maintenance operation phase is expected to have lower emissions than the initial drilling phase; however, the emissions from the initial drilling phase will be conservatively applied over the entire duration of operation to determine the total annua l (tons/365 days) potential emissions. Anadarko is still in the process of finalizing the maximum hourly (1-hour), maximum daily (24-hour) and annual emissions resulting from the proposed exploratory drill ing activity over entire duration of operation. A summary of the proposed maximum hourly, daily, and annual emissions from the proposed drilling operations will be included in the final modeling report.



## 2.4 Q/D A NALYSIS

Anadarko will complete the Q/d calculation based on the potential-to-emit from all the drillships in order to assess potential impacts of the proposed dr illing operations on the nearest Class I areas. 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 y ear) 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 annualized 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 intermitt ently or seasonally will be adjusted to account for year round operation. Based on the preliminary analysis, a Class I area AQRV analysis is required for this project because the Q/d ratio for th e proposed source is expected to be greater than 10. Please note that Anadarko is still in the process of finalizing potential hourly emission rates, however Anadarko does not reasonably expect the Q/d to be below 10. A copy of the Q/d analysis will be included in the final modeling report.

11 Based on Personal Communication: Phone conversation between Mr. Stan Krivo (EPA Region IV) and Mr. Rahul Pendse (Trinity) on September 21, 2012.

12 U.S. Forest Service – Air Quality Program, National Pa rk 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 Petroleum Corporation 8 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 analysis is required to demonstrate that emissions of these pollutants do not cause or contribute to a violation of a National Ambient Air Quality Standard (NAA QS) or exceed a Class II area PSD Increment. Per
Guideline , this is accomplished by conducting an Air Dispersion Modeling analysis. 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 ex ceeds applicable ambient concentration thresholds commonly referred to as the Significant Impact Levels (SILs) also known as Modeling Significance Levels (MSLs). In a ddition, 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 “cumula tive” analysis. For pollutants with modeled concentrations greater than the SIL, PSD regulations require a NAAQS analysis and a PSD Increment analysis. A full impact analysis is performed at each off-property receptor where the maximum concentration exceeds the applicable SIL as determined in the significance analysis. The NAAQS analysis demonstrates that the post-project emissions in conjunction with other applicable emi ssions from existing sources will not cause nor contribute to an exceedance of the applicab le air quality standard. The PSD Increment analysis demonstrates that the proposed project in conjunction with other applicable emissions from existing sources will neither cau se nor contribute to an exceedance of the applicable air quality standard.

Table 3-1 lists the SILs, NAAQS, and PSD Increments for all relevant PSD-regulated pollutants for this dispersion modeling analysis.Anadarko Petroleum Corporation 9 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 5 150 3 30 10

PM 2.5 24-hour

Annual 1.2

0.3 35 5

12 6 9

4 4

--
1 Not to be exceeded 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 th e 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 mu ltiple 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 been proposed yet. However, interim modeli ng 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 SO 2 standard

have not been proposed yet. However, interim modeli ng 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 af ter 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 the 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 appli cable 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 determin e whether the emissions associated with the proposed OCS source would cause a significant impact upon the area surrounding the OCS source. 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, Nove mber 9, 2005; and EPA’s New Source Review Workshop Manual (DRAFT) (1990).Anadarko Petroleum Corporation 10 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., NAA QS and PSD Increment) are not required for that pollutant and the project’s impact is considered not significant. If, however, modeled impacts exceed the SIL for any averaging period, a full impact (i.e ., NAAQS and PSD Increment) analysis is required for that pollutant to demonstrate that the project neither causes nor contributes to any exceedances.

Based on the preliminary emission calculations a nd previous experiences, Anadarko expects that concentration of all pollutants will be less than thei r respective SILs. Hence, in that case, full impact analysis will not be required for these pollutants. If the significance levels for applicable pollutants and averaging periods are exceeded in the final modeling anal yses, a regional inventory will be developed and the impacts caused by the OCS sour ce and the regional inventory will be compared against the NAAQS and Increment standards. Hence, this protocol does not include procedures to conduct the full impact analysis. If the full impact an alysis is necessary, an addendum to this protocol will be submitted to EPA Region IV for review a nd approval. A special consideration should be given to PM 2.5 since direct comparison with PM 2.5 SIL is not allowed without prior approval from the regulatory agency. Please refer to Section 3.1. 3 for further discussion regarding this topic.Anadarko Petroleum Corporation 11 Trinity Consultants F IGURE 3-1. G ENERAL PSD M ODELING F LOWCHARTAnadarko Petroleum Corporation 12 Trinity Consultants 

### 3.1.1 S IGNIFICANT 

### I MPACT 

### A REA 

### (SIA)

For all applicable pollutants with modeled impacts gr eater than or equal to the appropriate SIL, the significance model results determine the Significant Im pact Area (SIA). If the significance levels for applicable pollutants and averaging periods are exceeded in the final modeling analyses, a SIA will be determined after obtaining prior approval from EPA Region IV. All regional sources of the pollutant in question within the SIA are assumed to potentia lly contribute to ground-le vel concentrations and will be evaluated for possible inclusion in the NAAQS and PSD Increment analyses after discussions with EPA Region IV.



### 3.1.2 P RE 

### -C ONSTRUCTION 

### M ONITORING 

### A NALYSIS

In addition to determining whether the applicant can forego further modeling analyses, the PSD Significance Analysis is also used to determin e whether the applicant is exempt from ambient monitoring requirements. To determine whether pre-construction monitori ng should be considered, the maximum impacts attributable to the emissions increases from a project are compared with the Significant Monitoring Concentrations (SMCs) shown in Table 3-1. If either the predicted modeled impact from 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 greater than the SMC, an applicant may provide ex isting data 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 project will not be required by U.S. EPA Region IV. If the predicted modeledimpacts exceed the SMCs, Anadarko will request that U.S. EPA Region IV waive the preconstruction monitoring requirements of 40 CFR 52.21(m) and allow the use of ambient monitoring data from the nearest onshore station which should provide a conservative estimates of the background pollutant concentrations in lieu of pre-construction monitoring. A representative monitoring station will be selected after obtaining prior approval from EPA Region IV.

Additionally, although no SMCs have been established for 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 im pact analysis, including the gathering of ambient ozone data. As the NO X emissions from the proposed OCS source are 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 the proposed operation. Wh ile it is possible that the proposed project’s NO X emissions could cause an increase in ozone form ation, a minimal impact on ozone formation attributable to a project’s NO X emissions is typically demonstrated through compliance with the NO 2 standard. Nonetheless, as ozone monitor data is readily available from onshore monitoring stations, Anadarko requests U.S. EPA Region IV to waive th e ozone pre-construction monitoring requirement and allow the use of existing ozone monitor data from a representative onshore station that can be used as an estimate of the background concentrations in the remote offshore location. Anadarko will use the ozone monitor data from a representative onshore station and results of modeling for NO 2 NAAQS to demonstrate that the emissions resu lting from the proposed project will not cause or

14 U.S. EPA New Source Review Works hop Manual (Draft, 1990), pages C.18–19.Anadarko Petroleum Corporation 13 Trinity Consultants contribute to violations of the 8-hour ozone NAAQS of 0.075 ppm. The procedures used to determine a representative onshore ozone monitor w ill be documented in the final modeling report.

Please see Section 5.10 for further discussion on the se lection of the appropriate onshore station.



### 3.1.3 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). 15 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 us ing the current regulatory air dispersion models for a pollutant like
PM 2.5 , which can be formed from precursors through at mospheric reactions downwind of an industrial source poses several technical difficulties. Therefore, when implementing the current U.S. EPArecommended model and relevant PSD 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 memorandum 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 annual average of PM 2.5 concentration based on 1 year of s ite-specific meteorological data be compared to the annual SIL. 16 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 year of site-specific meteorological data be compared to the 24-hour SIL. Anadarko is proposing to use the annual and 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 de terminations for PM 2.5 . As such, the promulgated PSD increments, SILs,
and SMCs for PM 2.5 have been incorporated into Ta ble 3-1 of this modeling protocol.

The EPA has historically allowed the use of screeni ng tools to help facilitate the implementation of the PSD program and streamline the permitti ng process in circumstances where proposed construction is projected to have an insignifi cant (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 PM 2.5 in 2010. 17 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
. 18 The Court concluded that the PM 2.5 SMC provisions (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

15 Federal Register, Vol. 73, p. 28,321.

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

17 73 FR 28321 and 75 FR 64864.

18 Sierra Club v. EPA, No. 10-1413 (D.C. Circuit), 2013 WL 216018.Anadarko Petroleum Corporation 14 Trinity Consultants vacate the SIL provisions in Sections 40 CFR 51.16 6(k)(2) and 40 CFR 52.21(k) (2) of the regulations so that the EPA could correct an error in these provi sions 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 reflects 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 CFR 51.166(k) and 40 CFR 52.21 (k).
The draft Guidance for PM 2.5 permit modeling incorporates the modeling procedures and recommendations from the March 23, 2010, gu idance memorandum "Modeling Procedures for Demonstrating Compliance with PM 2.5 NAAQS," and further 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 recommendations 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 analysis in some circumstances where the EPA had called for permitting authorities to consider 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 advised 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 40 CFR 52.21(m). However, the EPA believes PSD permit applicants may continue to meet the preconstructi on monitoring requirements in these regulations by using data from existing monitors that are determ ined by the applicable permitting authority to be representative 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 interi m, the EPA believes permitting authorities may continue to apply SILs for PM 2.5 to support a PSD permitting d ecision, but permitting authorities
should take care to ensure that SILs are not used in a manner that is inconsistent with the requirements of Section 165(a)(3) of the CAA....” 19

Per EPA draft guidance for PM 2.5 modeling, “Any permitting authority wishing to use a particular SIL value as a screening tool in a significant impac t analysis should determine whether a substantial portion of the NAAQS has already been consumed. Preconstruction monitoring data (or adequately representative onshore monitoring data from an exis ting onshore monitoring network) should be evaluated against the respective PM 2.5 NAAQS. If the difference between the NAAQS and the 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 valu e will not cause a new NAAQS violation...” The OCS source that demonstrates its impact does not exceed a SIL at the relevant location is not required to conduct more extensive air quality analysis (full impact analysis) or modeling to demonstrate that its emissions, in combination with the emissions of other sources in the vicinity, will not cause or contribute to a violation of the NAAQS at that location.

19 http://www.epa.gov/scram001/guidance/guide/D raft_Guidance_for_PM25_Permit_Modeling.pdf

.Anadarko Petroleum Corporation 15 Trinity Consultants Per EPA draft guidance for PM 2.5 modeling, EPA proposed four different “assessment” cases that define what air quality analyses, if any; an app licant would conduct to demonstrate compliance with
the PM 2.5 NAAQS (annual and 24-hour). Based on the prel iminary emission estimations the project
direct PM 2.5 and NO X emissions are expected to exceed their respective SERs and hence will fall
under Case 3 where the direct PM 2.5 emissions are greater than the SER of 10 tpy and either NO X and

SO 2 precursor emissions are greater than their resp ective SERs of 40 tpy. Since the proposed OCS source is expected to emit quantities of PM 2.5 precursors above the respective SERs for Case 3, some assessment of their potential contribution to secondary PM 2.5 is necessary. Per EPA draft guidance for

PM 2.5 modeling , the assessment of the precursor emission impacts on secondary PM 2.5 formation may be: a) qualitative in nature; b) based on a hybrid of qualitative and quantitative assessments utilizing existing technical work; or c) a full quantitative photochemical grid modeling exercise.

Anadarko proposes to use a hybrid approach of qualitative and quantitative assessment to estimate secondary PM 2.5 impacts for comparison of the proposed new or modifying source’s total ambient impact (i.e., primary and secondary impacts) to the applicable SIL. Methodologies that can be used to address secondary PM 2.5 emissions have also been discussed in the National Association of Clean Air Agencies (NACAA) document titled “PM 2.5 Modeling Implementation for Projects Subject to National Ambient Air Quality Demonstration Requi rements Pursuant to New Source Review.” However, EPA concluded that these methodologies can lead to overly conservative estimation of secondary PM 2.5 formation in the EPA draft guidance document for PM 2.5 modeling.

CALPUFF model can be used to account for many of the complex atmospheric physical and chemical mechanisms that influence PM 2.5 formation. Additionally, CALPUFF account for the size or mass of particulate emissions and, therefore account for the difference in gravitational settling and deposition rates that occur for different particle sizes. The chemical transformation schemes implemented in CALPUFF could be used to predict secondary PM 2.5 formation (primarily due to photochemical reaction that transforms NO X and SO 2 after reacting with ammonia into forming particulate nitrates and sulfates) from atmospheric processes. 20

Ammonium nitrate formation is a fairly slow pro cess and would not occur in the areas with relatively high direct PM 2.5 impacts, and in areas generally with low ammonia background available. Therefore, secondary formation of PM 2.5 is not likely to overlap with primary PM 2.5 levels. By the time that there is any ammonium nitrate formation, the impacts of direct PM 2.5 should be very low.
The conversion of SO 2 to sulfates is fairly rapid, therefore the contribution from sulfates are expected to occur close to the drillship and at the sea itself. Since the NO X and SO 2 standards are extremely restrictive, being below the SILs would likely prevent the pollutants from impacting secondary formation significantly enough to result in a violation of the PM 2.5 standards. However, it is possible that some transformation into nitrates and sulfates from this source may occur and be transported
downwind.

Anadarko proposes to use CALPUFF to estimate 24-hour and annual concentrations of ammonium
sulfate and ammonium nitrate. CALPUFF tracks ammonium sulfate as SO 4 and ammonium nitrate

20 Based on “Guide for Applying the EPA Class I Screen Methodology with the CALPUFF Modeling System” by Earth Tech, Inc, (September 2001), page 13, http://www.src.com/cal puff/Screen_Guide.PDF

.Anadarko Petroleum Corporation 16 Trinity Consultants as NO 3
. 21 Hence, Anadarko proposes to estimate bot h the 24-hour and annua l concentration from post-processing of CALPUFF model as described below.

Secondary PM 2.5 (μg/m 3 ) = SO 4 (μg/m 3 ) + NO 3 (μg/m 3 ) (for both 24-hour and annual standards) Equation 1

Total PM 2.5 (μg/m 3 ) = Direct PM 2.5 (μg/m 3 ) + Secondary PM 2.5 (μg/m 3 ) (for both 24-hour and annual standards) Equation 2

If Total PM 2.5 (μg/m 3 ) results are less than PM 2.5 SIL, then no full impact analysis will be required. As a conservative estimation Anadarko will turn deposition algorithm off when evaluating the PM 2.5 impacts and evaluate the qualitative assessment in the final modeling report. A description of Anadarko’s approach to account for secondary PM 2.5 formation in the CALPUFF model is discussed
in Section 5-13.



## 3.2 A DDITIONAL 

## I MPACTS 

## A NALYSIS

PSD regulations require that three additional imp act 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 any commercial, residential, and industrial growth associ ated with the proposed facility, 2) an analysis of the impairment to soils, vegetation, and animals th at 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 ma y 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 additional impacts analyses. Anadarko believes that the approach outlined will satisfy Anadarko’s obligations in this regard for this project.



### 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 quan titatively or qualitatively. Typically, the amount of residential growth depends on the size of the av ailable work force, the number of new employees, and the availability of housing in the area. Associ ated commercial and industrial growth consists of new sources providing goods and services to the ne w employees and to the new industrial source itself. Because of the seasonal and temporary na ture 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 U.S EPA, through the CAA, has promulgated primary and secondary ambient air quality standards. The primary air quality standards are set at levels necessary to provi de an adequate margin of safety to protect human health. The secondary standards are set at levels to provide for protection of public welfare, where welfare is defined to include the following: soils, water, vegetation,

21 Based on “Guide for Applying the EPA Class I Screen Methodology with the CALPUFF Modeling System” by Earth Tech, Inc, (September 2001), page 13, http://www.src.com/cal puff/Screen_Guide.PDF

.Anadarko Petroleum Corporation 17 Trinity Consultants manmade materials, animals, wildlife, weather, visi bility, climate, and damage to or deterioration of
property. 22 Table 3-1 shows the secondary NAAQS for each relevant regulated 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 the sec ondary NAAQS, it will be presumed that emissions from the proposed sources will not result in ha rmful effects to either soil or vegetation. 23
Alternatively, due to the location of the proposed exploration activities being more than 100 km from
the nearest shoreline if ambient air concentrations are found to be less than the SILs, 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 Source Review Workshop Manual , visibility impairment analysis should be performed for impacts that occur within the area affected by proposed project. 24 The EPA’s Workbook for Plume Visual Impact Screening and Analysis ( Workbook ) provides guidance for conducting a visibility impairments analysis through the use of VISCREEN, a plume visibility impact
model. 25 The methods in this workbook are desi gned for Class I area impacts; however, the procedures are generally applicable to other areas as well. The VISCREEN model 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.

If the potential for visibility impairment is indicat ed, 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 specified “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 area that is more than 50 km from the drilling location, the 50 km distance will be used in the VISCREEN analysis.

22 Sections 109 and 302 of the Clean Air Act.

23 U.S. EPA, Office of Air Qu ality Planning and Standards, New Source Review Workshop Manual , Research Triangle Park, NC, October 1990.

24 U.S. EPA, New Source Review Workshop Manual (Draft): Pr evention of Signific ant Deterioration and Nonattainment Area Permitting , October 1990.

25 U.S. EPA Office of Air Qual ity Planning and Standards. Workbook for Plume Vis ual Impact Screening and Analysis . Research Triangle Park, NC. EPA-450/4-88-015.Anadarko Petroleum Corporation 18 Trinity Consultants 

## 4. C LASS 

## I A IR 

## Q UALITY 

## D ISPERSION 

## M ODELING 

## R EQUIREMENTS

Two principal air quality impacts are consider ed for Class I areas: PSD Increments for NO X , PM 2.5 , and PM 10 , and AQRVs. This section of the protocol describes the 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 demonstrate through air quality modeling that the emissions increases from the proposed project w ill 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 increments are lower) than Class II areas. A significant contribution to Class I Increment consumption is defined as a modele d concentration in excess of the significant impact levels (SILs) summarized in Table 4-1, which were original ly 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 esta blished 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 PSD Significant Emission Rates (SERs), the Class I area PSD Increment analysis will be completed for each of these pollutants. Although the propo sed OCS source also has the potential to emit PM 2.5 in excess of the SER, a Class I Area Increm ent analysis specifically including PM 2.5 would be no different than the analysis conducted using PM 10 as the AQRV analysis (emission speciationAnadarko Petroleum Corporation 19 Trinity Consultants discussed in Section 5.6) already addresses fully speciated PM 10 emissions including all species that
contribute to PM 2.5 (e.g., fine filterable and condensable PM emissions.) 26

If the significance levels for NO X, PM 2.5 , and PM 10 are exceeded, a regional inventory will be developed and the impacts caused by the OCS sour ce 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: 27

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 enjoym ent of a visitor's visual experience of a
Federal Class I or Class II area. This de termination must be made on a case-by-case basis taking into account the geographic exte nt, intensity, duration, frequency and time of visibility impairments, and how these factor s correlate with (1) times of visitor use of the Class I area, and (2) the frequency and timing of natural 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, deterioration 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 th e current 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 incl ude nitrogen deposition, sulfur deposition, and visibility degradation. Based on discussion withFWS, Anadarko is required to perform AQRV analyses for all three indicators mentioned above for Breton and St. Marks Class I areas. 28 Based on guidance received from FS, the AQRV analysis for Bradwell Bay is required to be performed for

26 VISTAS, Protocol for the Application of the CALPUFF M odel for Analyses of Best Available Retrofit Technology (BART) , Revision3.2, revised August 31, 2006. http://www.vistas-sesarm.org/documen ts/BARTModelingProtocol_rev3.2_31Aug06.pdf

27 U.S. Forest Service – Air Quality Program, National Pa rk 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.

28 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 Webs ter (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 Petroleum Corporation 20 Trinity Consultants nitrogen deposition, sulfur depositi on, and ozone. An AQRV analysis for visibility at Bradwell Bay is not required. 29



### 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 Cl ass I area will be evaluated against the deposition assessment threshold (DAT) values for sulfate and nitrate 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 impact threshold and coastal ecosystems have evolved under naturally highe r 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 all Class I areas in the Eastern United

States. 30 The procedures specified in the FLAG Ph ase I report (revised 2010) will be used to model nitrogen and sulfur deposition. 31 For sulfur, both wet and dry fluxes of SO 2 and sulfates (SO 4 ) will be modeled. The sum of wet and dry deposition fluxes for SO 2 and SO 4 represents the total sulfur de position as shown in Equation 3.



###     dry 424 2 wet 424 2 ]SO)flux[(NH]flux[SO ]SO)[(NHflux ][SOflux (kg/ha/yr) Deposition Sulfur

   

Equation 3

For nitrogen, the dry flux for NO

x , and wet and dry deposition fluxes for nitrates (NO 3 ), nitric acid (HNO 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 represents the total nitrogen deposition, as shown in Equation 4.



###  

])SO)flux[(NH ]flux[HNO ]NO flux[NH (flux[NOx] ]SO)flux[(NH]flux[HNO ]NO flux[NH (kg/ha/yr) Deposition Nitrogen

dry424 3 34 wet 424 3 34

      

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 depos ition will be modeled for SO 4 and NO 3 . The contribution of the proposed project to the deposition of nitrogen and sulfur

29 Based on Personal Communication, Phone conversa tion Ms. Melanie Pitrolo ( FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012, visibility has not b een established as an AQRV for Bradwell Bay.

30 U.S. National Park Service (NPS) - Air Resources Division a nd 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.nature.nps.gov/air/Pubs/p df/flag/nsDATGuidance.pdf.

31 U.S. Forest Service – Air Quality Program, National Pa rk 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 Petroleum Corporation 21 Trinity Consultants species in each Class I area will be estimated and assessed against the appropriate DAT in the modeling report.



### 4.2.2 V ISIBILITY

Visibility can be affected 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 (t he 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 formed 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 have 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 th e light extinction coefficient ( b ext ). To determine a change in regional haze, the percentage ch ange of the light extinction coefficient (  b ext )
will be evaluated as shown in the following Equation 5:

background ext

projectext

ext b b b

, ,  Equation 5

The Δ b 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 methods 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 attribute 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 “...tends to magnify the actual visibility
effects” of a source. 32 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 woul d appear to exclude roughly 7 days per year from consideration. In our judgment, this approach will effectively capture the

32 U.S EPA, Regional Haze Regulations and Guidelines for Best Available Retrofit Technology (BART) Determinations, July 6, 2005.Anadarko Petroleum Corporation 22 Trinity Consultants sources that contribute to visibility impairme nt in a Class I area, while minimizing the likelihood that the highest modeled visibility impacts might be caused by unusual meteorology or conservative assumptions in the model.” The use of the 98th percentile approach has also been formalized in the FLAG Phase I report (revised 2010).

In the revised FLAG Phase I report (revi sed 2010), FLAG has proposed a new algorithm for calculating the background extinction coe fficient based on the revised method in the Interagency Monitoring of Protected Visual Environments (IMPROVE) protocol. IMPROVE protocols for reconstructing ambien t light extinction from measured aerosol species are used in evaluating compliance unde r 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 report (revised 2010), and so Trinity shall use these procedures to calculate the backgr ound 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 monthly average relative humidity adjustment particular to each Class I area, applied to b ackground 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 results tend to be smoothed, since peak short-term humidity events are not considered.

Procedures specified in the FLAG Phase I repor t (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 report (revised 2010): 33

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 μ g/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

33 U.S. Forest Service – Air Quality Program, National Pa rk 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 Petroleum Corporation 23 Trinity Consultants Monthly 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 report (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 Petroleum Corporation 24 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 th e annual average background concentrations at
Breton and St. Marks obtained from Table 6 of the FLAG Phase I report (revised 2010) are provided in Table 4-4. 34 These values will be used to calculate backgr ound 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 methodology presented in Figure 5 of the FLAG Phase I report (revised 2010) will be used to calculate large and small nitrates, large and small sulfates, and large and small organic mass.

34 U.S. Forest Service – Air Quality Program, National Pa rk 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 Petroleum Corporation 25 Trinity Consultants The extinction coefficient attributable to emissions increases from the proposed project
b ext,project will also calculated. The extinction resulting from the project is calculated as shown in Equation 7 35 :

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 μ g/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 Δ b ext percentage change results us ing “Method 8” will be calculated and presented in the modeling report.



### 4.2.3 O ZONE

Ozone is a toxic air pollutant that is form ed on warm, sunny days when its precursors NO and VOC react in the presence of sunlight . Because ozone is a regional pollutant, precursor sources both near and far from Class I areas can contribute to ozone formation. However, due to the complex photochemical reac tions that are involved in the formation of ozone, it is difficult to quantify specific rela tionships 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 oz one on vegetation and the levels of ozone generally known to be phytotoxic in Class I ar eas 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 e xposure as a result of the proposed drilling operations on vegetation at Bradwell Bay. 36

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

35 Equation 7 has been obtained based on Equation 6 except th at there will be no project extinctions due to EC and sea salt, since no elemental carbon or se a salt will be emitted from the proposed proj ect, as described in Section 2 of the report.
36 Based on Personal Communication, Phone conversation between Ms. Melani e Pitrolo (FS) to Mr. Rahul Pendse (Trinity) on October 18, 2012.Anadarko Petroleum Corporation 26 Trinity Consultants deposition thresholds at Bradwell Bay as a method of addressing impacts of ozone on the vegetation at Bradwell Bay. 37

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 th e 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 de duced that there are no ozone impacts on the vegetation at Bradwell Bay. 38 It should also be noted that if the PSD Class I area modeling analysis demonstrates that Class I area SILs are not exceeded for NO 2 , then that would provide additional demonstration that no si gnificant 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 procedures for conducting an analysis for assessing impacts of ozone exposure on the vegetation at Bradwell Bay. The ambient ozone monitoring data from Sumatra for years 2001 through 2003 respectively will be provided in the final modeling
report.

37 Based on Personal Communication, Phone conversation between Ms. Me lanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity) on October 18, 2012. Pe r discussion with Ms. Melanie Pitrolo (FS) and Mr. Rahul Pendse (Trinity), visibility has not been establishe d as an AQRV for Bradwell Bay.

38 Per Section 3.4.5 of Phase I Report of the Federal L and Managers’ Air Quality Related Values Workgroup (FLAG)--Revised, 2010

.Anadarko Petroleum Corporation 27 Trinity Consultants 

## 5. M ODELING 

## M ETHODOLOGY AND 

## I NPUTS

This section of the modeling report describes the mo deling 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 pollutant plume over time and space given data i nputs. 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 m odel is suitable for the evaluation of source impacts depends on (1) the meteorological and topogra phical 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 pollu tant transport (i.e., distances greater than 50 km) is the CALPUFF modeling system. The EPA-a pproved version (Version 5.8) of the CALPUFF model will be used to determine the possible impa cts of the proposed Anadarko drillships on Class I PSD Increment and AQRV at respective Class I areas. The post-processing of the CALPUFF data will be performed using the recently EPA-approved version (Version 6.221) of the CALPOST. 39

CALPUFF is a multi-layer, multi-species, non-steady-state Lagrangian puff model, which can simulate the effects of time- and space-varying me teorological conditions on pollutant transport, transformation, and removal. For this refined an alysis, meteorological fields generated by CALMET will be used as inputs to the CALPUFF model to ensu re that the effects of terrain and spatially varying surface characteristics on meteorology are considered.

In addition to meteorological data, the CALPUFF mo del 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. Th is file contains all of the necessary information 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 , the applicable guidance memorandum from Support Center for Atmospheric Modeling (SCRAM) website, FLAG Phase I Report - revised (October 2010), and IWAQM documents. The fo llowing sections describe the modeling domain, meteorological data, background concentrations, a nd model implementation to be used for the analysis of the proposed Anadarko drilling operations.



## 5.2 M ODEL 

## D OMAINS

The Class I and Class II modeling analysis will be pe rformed in the Lambert Conformal Conic (LCC) coordinate system based on the design of the VISTAS Regional Haze Rule (RHR) modeling, with

39 http://www.epa.gov/ttn /scram/dispersion_prefrec.htm#calpuff.Anadarko Petroleum Corporation 28 Trinity Consultants standard parallels of 33o N and 45 o N latitude, and reference latitude and longitude of 40o N and 97o W respectively. 40 VISTAS RHR Model Domain 2 will be utilized as the CALMET meteorological
domain. 41 The different VISTAS RHR Model Domain s 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 CALMET 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 will be 4 km.

40 VISTAS, Protocol for the Application of the CALPUFF M odel for Analyses of Best Available Retrofit Technology (BART) , December 22, 2005, revised August 31, 2006.

41 Phone conversation between Ms. Jill Webster (F LM, Breton NWR) and Mr. Rahul Pendse (Trinity) on October 12, 2012; and Email from Ms. Jill Webster (FWS) and Mr. Dhesikan Venkatesan (Trinity) sent on October 10,
2012.Anadarko Petroleum Corporation 29 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 face height of each cell indicates its vertical extent. The vertical domain will be com posed 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 informati on 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. 42 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 throu gh a single stack which would be representative of the expected impacts. The stack will be modele d 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 the Class II analysis the worst-case lease block w ould be the closest distance to the nearest Class II receptor placed 25 miles from the state seaward boundary. For purposes of the modeling analysis, the drillship emissions will be modeled as a single point source with the emissions emitted through a single stack and the worst-case support vessels emissions will be modeled as a series of volume sources by placing ten volume sources equi-distance from each other and with equal emissions. These volume sources will be placed directly in line of the nearest receptor at nearest Class I and Class II areas along the 25 mile radius.

42 VISTAS, Protocol for the Application of the CALPUFF M odel for Analyses of Best Available Retrofit Technology (BART) , December 22, 2005, 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/R95-006, December 1998.Anadarko Petroleum Corporation 30 Trinity Consultants Additionally, the stack parameters for this single stack will be based on the stacks associated with the main engines on the drillship, wh ich are the largest sources of PM 2.5 , PM 10, CO, SO 2 , and NO 2 emissions. As a conservative estimate, the lowest exhaust flow rate meas ured across all operating
loads from the stack test results have been used to determine th e lowest stack gas exit velocity. 43 Similarly, as a conservative estimate the lowest temperature measured across all operating loads from
the stack test data have been used in the modeli ng analysis. The stack height represents the height above the sea level (water line) to the main engine stack.

A summary of the modeling parameters, source para meters and emission rates used in the modeling analysis shall be provided with the final modeling report.



## 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. 44 The database provides the location (lat/long, dd) coordinates and elevation in formation 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 conve rsion factors and will be used in these Class I analyses.



## 5.5 R ECEPTOR 

## L OCATIONS FOR 

## C LASS 

## II A REAS

The seaward boundaries and Air Quality Control Re gions 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 seaward boundaries of Louisiana, Mississippi, Alabama and Florida. The receptors were placed at 1-km intervals as per Guidance received from EPA region IV . The actual sets of receptors used in Class II analysis were provided by EPA Region IV. 45 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. The full NAAQS and PSD Increment analyses if required will be conducted using only receptor locations at which impacts predicted in the Signi ficance Analysis exceeded the SILs.



## 5.6 E MISSIONS 

## S PECIATION

Modeling of visibility impairment due to PM emi ssions requires that the components of the exhaust stream be speciated because different 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.

43 Based on Personal Communication: P hone conversation between Mr. Stanle y Krivo (EPA Region IV) and Mr. Rahul Pendse (Trinity) on October 10, 2012.

44 http://www.nature.nps.gov/ai r/maps/receptors/index.cfm

45 Based on Personal Communication, E-mail from Mr. Stan Krivo (EPA Region IV) and Mr. Rahul Pendse (Trinity) on October 1, 2012.Anadarko Petroleum Corporation 31 Trinity Consultants 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 drilli ng operations. Therefore, Anadarko proposes the use of particle size-specific emission factors for large diesel fired engines from AP-42, Table 3.4-2, Particulate and Particle-sizing Emission Factors for Large Uncontrolled Stationary Diesel Engines (October 1996) to determine PM specia tion 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 respec tive state seaward boundary, the entire modeling domain 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 leve l 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 do wnwash 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. Hen ce, due to the relatively large distance of the proposed drillship from the Class I and Class II ar ea, building downwash will not be enabled. 46



## 5.9 B ACKGROUND 

## C ONCENTRATIONS

If the modeled impacts exceed the SILs for at least one averaging period, a background concentration
will be established to be combined with th e modeled impacts for evaluation of the design concentration against the NAAQS. Selection of th e existing onshore monitoring station will depend on following three criteria identified in the NSR Workshop Manual: (1) monitor location, (2) quality of the data, and (3) currentness of the data. Based on previous guidance received from U.S. EPA Region IV, existing onshore monitoring stati ons, depending on availab ility and the pollutant monitored, may be conservatively used to determ ine the background concentration for the project. The procedures used to determine a representative onshore monitoring station will be documented in the final modeling report.



## 5.10 CALMET (M ETEOROLOGICAL 

## D ATA 

## ) P ROCESSING

CALMET is the meteorological preprocessor that compiles 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 received from the FLM and EPA Region IV, 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

46 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.Anadarko Petroleum Corporation 32 Trinity Consultants Environmental Protection (DEP) will be used in this analysis. 47 No additional meteorological data processing is expected for this analysis. In lieu of recent discussions with EPA Region IV 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.



## 5.11 CALPUFF P ROCESSING

Using the data provided by CALMET, CALPUFF simula tes the dispersion, deposition, and chemical transformation of discrete puffs of mass from 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 e ffects, stagnation, or recirculation.

Emissions data and stack parameters will be entered into CALPUFF as previously described under Section 5.3 of this protocol. Due to the relativ ely large distance of the proposed drillship from the Class I and Class II area, building downwash will not be enabled. 48

This analysis will be performed with the depositi on and chemical transformation 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 depos ition rates of gases and particulate matter as a function of geophysical pa rameters, meteorological conditions, and pollutant species. An empirical scavenging coefficient appr oach using default optio ns will be enabled in CALPUFF to compute the depletion and wet de position fluxes due to precipitation scavenging.

The CALPUFF model is capable of simulating linear chemical transformation effects by using pseudo-first-order chemical reaction m echanisms for the conversions of SO 2 to SO 4 , and NO X , which consists of nitrogen oxide ( NO) and nitrogen dioxide (NO 2 ), to NO 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. 49 There are two user-selected input parameters that affect th e MESOPUFF II chemical transformation, ammonia
concentrations and ozone concentrations. The sel ection 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, spatially varying observations. For this analysis, Anadarko proposes the use of data from the monitor at Sumatra, Florida (code - SUM 156) due to its proximity to the

47 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 IV) and Mr. Rahul Pendse (Trinity) on October 10, 2012; and Email from Ms. Jill Webster (FWS) and Mr. Dhesikan Venkatesan (Trinity) sent on October 10, 2012. Th e meteorological data was obtained from Mr. Tom Rogers, Florida DEP, based on instructions from EPA Region IV.

48 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.

49 U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long-Range Transport Impacts , Research Triangle Park, North Ca rolina, EPA-454/R-95-006, December 1998.Anadarko Petroleum Corporation 33 Trinity Consultants modeling domain, as well as due to the availability of complete data from this station. Information on the monitoring station can be obtained from the CASTNET website. 50
Based on previous guidance received from FLM and EPA region IV, the ozone background level for the analys is will be set at 80 ppb.



### 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. 51
In the absence of an extensive monitoring network for ammonia and due to the limitation 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 10 ppb for grasslands. Based on previous guidance received from FWS, the ammonia background level for the analysis will be set at 3 ppb. 52



### 5.11.3 CALPUFF P ROCESSING 

### C ONTROL

CALPUFF modeling will be c onducted generally using the recommended regulatory default options specified in Appendix B of the IWAQM guidance. The integrated puff representation will be used and puff spli tting will be conservatively disabled.



## 5.12 CALPOST P OSTPROCESSING 

## A NALYSIS

The CALPOST postprocessor will be used to compute the ambient concentrations 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 II modeli ng levels, the total deposition of sulfur and nitrogen within each Class I area for assessment 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 the 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.

For estimating the extent of nitrogen and sulfur de position, POSTUTIL will first be used to combine the appropriate wet and dry fluxes of nitrogen- a nd sulfur-bearing species deposited as particles and gases. These combined fluxes will then be pro cessed using CALPOST to obtain the nitrogen and sulfur deposition values.

50 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.html

51 U.S. EPA, IWAQM Phase 2 Summary Report and Recommendations for Modeling Long-Range Transport Impacts , Research Triangle Park, North Ca rolina, EPA-454/R-95-006, December 1998.

52 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 Venkatesan (Trinity) sent on October 10, 2012.Anadarko Petroleum Corporation 34 Trinity Consultants Ammonium nitrate formation is a fairly slow pro cess and would not occur in the areas with relatively high direct PM 2.5 impacts, and area generally has low ammonia background available. Therefore, secondary formation of PM 2.5 is not likely to overlap with primary PM 2.5 levels. By the time that there is any ammonium nitrate formation, the impacts of direct PM 2.5 should be very low. The
conversion of SO 2 to sulfates is fairly rapid, therefore the contribution from sulfates are expected to occur close to the drillship and at the sea itself. Similarly in order to account for secondary PM 2.5 emissions CALPOST will be used to estimate NO 3 and SO 4 conversion rates and expressed as concentrations using the output concentration file from CALPUFF model runs. These results will then
added to direct PM 2.5 impacts from CALPOST analysis to estimate total PM 2.5 model impacts as
described in Section 3.1.3.

To determine the extent of change in light extinction from the proposed project, the Ammonia Limiting Method (ALM) will first 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 c onsumption of ammonia from the formation of
ammonium sulfates. The ALM will be a pplied based on guidance provided in the VISTAS BART Modeling Protocol

. 53 Visibility change will then be comput ed using “Method 8”, and results will be reported for the 98 th percentile for “Method 8”, for each of the three years of meteorological data
modeled.

53 VISTAS; Protocol for the Application of the CALPUFF M odel 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 Petroleum Corporation 35 Trinity Consultants 

## 6. M ODELING 

## R EPORT 

## C ONTENTS

A document that details the modeling methodolog y and summarizes the modeling results will be submitted to the FLM, as well as U.S. EPA Region IV. The air dispersion modeling report will include the following information:

▲ Brief overview of the proposed project;

▲ An area map indicating location of the source, receptors, model domain,and true north;

▲ Emissions rate summary for all proposed emi ssion sources, with units consistent with modeling;

▲ Stack parameter summary for all proposed em ission sources, with units consistent with modeling;

▲ Any calculations for stack parameters unless previously approved by U.S. EPA Region IV;

▲ 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 results to the applicable standards; and

▲ Electronic copies of all modeling files, including model input files, output files, met data with appropriate documentation if processing performed.

If required, Anadarko will submit additional info rmation to U.S. EPA Region IV and FLM upon
request.