-8400 -8400 -8300 -8200 -8100 -8000 -7900 -7900

-8800 -8700 -8600 -8500 -8400 -8300

-9100 -9200 -9300 -9400

-9500

-9600

-9700

-9800 -8800 -8900 -9000 -9100

-8700

-9200 -8200 -8100 -8000 -7900 -7800 -7900

-7900

-7900

-7900 -7900

-8000 -8000

-8100 -8000

-7900

-8500 -8600

-8700

-8900 -9100

-9200

-9300 -9400

-9500

-9600

-9700

-9800 -8300 -8200

-8900

-9000 -9100

-8800

-8900

-9300 -9200 -9400 -9500 -9100 -9000 

### B A A B 

# KC1007

G27776

Eni Petroleum US LLC Eni US Operating Co, Inc. 

# KC1008

G27777

Eni Petroleum US LLC Eni US Operating Co. Inc. 

# KC1009

G26780

Chevron U.S.A. Inc.



# SE39

G27779
Anadarko Petroleum Corporation 

# SE40

G27780
Anadarko Petroleum Corporation 

# SE41

(open)



# SE83

(open)



# SE84

(open) 

# SE85

(open) C -7900

-8000 -8100

-8200 -8300

-8400 -8500 -8600

-8700

-8800

-9100 -9000

-8900 -8800 -8400

-8500

-8800 -8600

-8700 -8900

-9000 -9100

-8600

-9100 -9000

-9100

-9100 

### C D 13,000 ft Radius

5,000 ft Radius 1,000 ft Buffer



# 1:12,000

Anchor Chart D Prepared for:



# Anadarko Petroleum Corporation

Feet 0 500 1000 2000 3000 4000 5000 

# Geodetic Information 

# Interpretive Information Location Map

INTERPRETATION: B. Monsalve, H. Danque GIS/CAD: B. Dillard DATE: 6/7/2010
REPORT NO: 4040-ANA-GOM FILE: 4040_Anchor_Chart_SE40_D_12.dwg SPHEROID: Clarke 1866 INVERSE FLATTENING: 1/294.978698

SEMIMAJOR AXIS: 6,378,206.40 ft SCALE FACTOR: 0.9996

PROJECTION: Transverse Mercator CENTRAL MERIDIAN: 93° W

DATUM: NAD27 LATITUDE OF ORIGIN: 0°

ZONE: UTM Zone 15 North FALSE EASTING: 1,640,416.666667 ft

LINEAR UNITS: Survey Feet FALSE NORTHING: 0 ft 32°N 97°W 96°W 95°W 94°W 93°W 92°W 91°W 90°W 89°W 88°W 87°W 86°W

97°W 96°W 95°W 94°W 93°W 92°W 91°W 90°W 89°W 88°W 87°W 86°W 25°N 26°N 27°N 28°N 29°N 30°N 31°N 32°N

25°N 26°N 27°N 28°N 29°N 30°N 31°N

Amery Terrace East Breaks Garden Banks Green Canyon Atwater Valley Destin Dome

Mississippi Canyon De Soto Canyon

Lloyd Ridge

Henderson

Florida Plain Lund

Lund South Walker Ridge Keathley Canyon Alaminos Canyon

Sigsbee Escarpment Texas Louisiana Mississippi Alabama

Florida

Brownsville Corpus Christi Port Lavaca Freeport

Galveston Houston The Woodlands

Port Arthur Lake Charles Lafayette

Morgan City New Orleans Biloxi Pascagula Mobile
Pensacola

Houma

0 25 50 100

Nautical Miles West Cameron

West Cameron West

West Cameron South West Delta Grand Isle Eugene Island

LN 5625 LN 5625 LN 55675 LN 55675keph2vsurveyvr16tmsurveykeph2vsurveyvr16tmsurvey

Notes: 1. keph2v survey: Lines have an azimuth of 90°/270°, Traces have an azimuth of 0°/180° Data Spacing for 3D seismic survey: Line 65.62 ft, Trace 41.01 ft. Line numbering increment is 5, Trace numbering increment is 1. Locations of every 75th Line and every 25th Trace are shown vr16tm survey: Lines have an azimuth of 90°/270°, Traces have an azimuth of 0°/180° Data Spacing for 3D seismic survey: Line 65.62 ft, Trace 82.02 ft. Line numbering increment is 5, Trace numbering increment is 1. Locations of every 75th Line and every 10th Trace are shown

2. Infrastructure information primarily from MMS database, these data, and AOA

database updated as of April 2010.

2500 Tanglewilde, Suite 120 Houston, TX 77063 (713) 532-2624 7532 Sandholdt Road, Suite 6 Moss Landing, CA 95039 (831) 633-7400 Grid North



# Sigsbee Escarpment (SE) SE39, SE40, and Vicinity

Gulf of Mexico Lowest Contour of Local Depression

Normal fault with seafloor expression. Symbol shows downthrown side and direction of fault dip -8500 Water Depth Contours, 25 ft interval:

Intermediate Contour

Index Contour

Seafloor slumps and shallow buried slumps Mass Transport Deposits (MTD) and debris flow deposit Bryant Canyon

Ridges and gullies associated with Bryant Canyon Reverse or thrust fault with seafloor expression. Symbol shows upthrown side and direction of fault dip



# SE40 

# Water Depth & Seafloor Features Showing Potential Anchor Touchdown Area for Proposed Well SE40 D N 9,415,000 N 9,420,000 N 9,425,000

N 25° 56' 00" N 25° 57' 00" N 25° 58' 00"



### N 9,410,000 LN 5700 LN 5775 LN 5850

LN 54250 LN 54325 LN 54400 LN 54475 LN 54550 LN 54625 LN 54700 LN 54775 LN 54850 LN 54925 LN 55000 LN 55075 LN 55150 LN 55225 LN 55300 LN 55375 LN 55450 LN 55525 LN 5925 LN 6000 LN 6075



### N 9,430,000

N 9,415,000

N 25° 56' 00" 

### N 9,420,000 N 9,425,000

N 25° 57' 00" N 25° 58' 00"



### N 9,410,000 LN 5700keph2v LN 5775 LN 5850

LN 54250 LN 54325 LN 54400 LN 54475 LN 54550 LN 54625 LN 54700 LN 54775 LN 54850 LN 54925 LN 55000 LN 55075 LN 55150 LN 55225 LN 55300 LN 55375 LN 55450 LN 55525 LN 55600 

### N 9,430,000

LN 5925 LN 6000 LN 6075E 1,955,000E 1,960,000E 1,965,000 W 92° 01' 00" W 92° 00' 00" W 91° 59' 00"E 1,970,000 W 91° 58' 00"TR 3155TR 3165TR 3175TR 3185TR 3195TR 3205TR 3215TR 3225TR 3235TR 3245TR 3255TR 3265TR 3275TR 3285TR 3295TR 3305TR 3315TR 3325TR 3335TR 3345TR 3355TR 3365TR 3375TR 3385TR 3395TR 3405TR 3415TR 3425TR 3435TR 3445TR 3455TR 3465TR 3475TR 3485E 1,975,000E 1,980,000 W 92° 02' 00"E 1,955,000E 1,960,000E 1,965,000E 1,970,000 W 92° 01' 00" W 92° 00' 00" W 91° 59' 00" W 91° 58' 00"TR 8445TR 8470TR 8495TR 8520TR 8545TR 8570TR 8595TR 8620TR 8645TR 8670TR 8695TR 8720TR 8745TR 8770TR 8795TR 8820TR 8845TR 8870TR 8895TR 8920TR 8945TR 8970TR 8995TR 9020TR 9045TR 9070TR 9095E 1,975,000E 1,980,000 W 92° 02' 00"



### N 25° 59' 00"

N 25° 59' 00"

LN 55600

Seafloor chutes 

### D A 2,000 ft radius circle around well surface location is

shown as required by Notice to Lessees 2009-G40 Proposed Well Surface Location and Designation

Subsurface Mapping Area 

## SE40

LN 6300 TR 8570 3D Seismic Survey Line, Trace, and Designation (LN=Line) (TR=Trace) Lease Block Boundary: Block Number, Lease Number with Operator and Primary Lease Holder shown

Approximate Maximum Anchor Radius - 13,000 ft

Approximate Touchdown Point - 5,000 ft 1,000 ft buffer beyond approximate maximum anchor radius 

# Basemap InformationTR 8420TR 3145 LN 54175 LN 54175 Possible deepwater benthic communities

LN 54100

LN 54025 LN 54100

LN 54025 

### N 9,405,000 N 9,405,000 N 25° 55' 00"

N 25° 55' 00" Mound features representing displaced sediment blocks LN 6150 LN 6225

LN 6150 LN 6225TR 3135TR 8395

### D HYDROGEN SULFIDE INFORMATION

Discussions regarding geologic information are consid ered proprietary and have been omitted from this public copy EP. 

### Wells nearby in Keathley Canyon Blocks 91 9, 292, 470 and 681 have tested similar age sections as the proposed locat ions, SE 39 “A”, ”B”, “C” and “D” and SE 40 “A”, “B” , “C”, and “D” locations without encountering any H 2 

### S. These wells include th e Keathley Canyon (Exxon) 919 OCS-G 21447 #1, Keathley Canyon (BP) 292 OCS-G 25792 #1BP2, Keathley Canyon (Anadarko) 470 OCS-G 22360 #1, and the Keathley Canyon (Uni on Oil) 681 OC S-G 20949 #1. Since no (H 2 

### S) was encountered in any of these wells we request the area be classified as a
"zone where the absence of H2s has been confirmed.”

### E BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION

(a) Chemosynthetic Communities Report

The seafloor disturbing activities proposed in this plan are in appr oximately 8,336’-8,798’ of
water. The wells will be drilled with a DP Drillship or DP Semisubmersible drilling unit.

Maps

A map prepared using 3-D seismic data to depi ct bathymetry, seafloor and shallow geological features, surface locations of the proposed wells, and positions of anchors and chains relative to the proposed operations is included in Section A.

Analysis

Features or areas that could support high-density chemosynthetic communities are not located within 2000 feet of each proposed muds and cuttings discharge location.

Features or areas that could support high-density chemosynthetic communities are not located within 250 feet of any se afloor disturbances.

(b) Topographic Features Map

The proposed activities are not with in 1,000 feet of a no-ac tivity zone or within the 3-mile radius zone of an identified topographic feature. Th erefore, no map is requ ired per NTL No. 2008-G04.

(c) Topographic Features Statement (Shunting)

Anadarko does not plan to drill more than two wells from the same surface location within the
Protective Zone of an identifie d topographic feature. Theref ore, the topographic features statement required by NTL No. 200 8-G04 is not applicable.

(d) Live Bottoms (Pinnacle Trend) Map

The activities proposed in this pl an are not within 200 feet of any pinnacle trend feature with vertical relief equal to or greater than 8 f eet. Therefore, no map is required per NTL No. 2008-
G04.

(e) Live Bottoms (Low Relief) Map

The activities proposed in this plan are not within 100 feet of any live bottom low relief features. Therefore, no map is required per NTL No. 2008-G04.

### (f) Potentially Sensitive Biological Features

The activities proposed in this plan are not within 200 feet of any potentia lly sensitive biological features. Therefore, no map is required per NTL No. 2008-G04.

(g) Remotely Operated Vehicle (ROV) Monitoring Survey Plan

Sigsbee Escarpment Blocks 39 and 40 is located within Deepwater Grid Area 8. This grid is considered to have “inadequate ROV survey c overage”, and, therefore, under the guidance set out in NTL No. 2008-G06, a Remotely Operated Ve hicle Monitoring Survey Plan is required.

Pursuant to NTL 2008-G06, operators may be re quired to conduct remotely operated vehicle (ROV) surveys during the propo sed operations for the purpose of biological and physical
observations.

Anadarko is familiar with the ROV survey and reporting provisions of NTL 2008-G06; and if required, will conduct a survey.

Anadarko will utilize ROV equipped with video imaging capabilities. The survey pattern will
consist of six transects centered on the well lo cation with tracks extending approximately 100 meters away from the well on bearings of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees and 330 degrees. The seafloor will be videotaped continuously along each track.

Anadarko will make biological and physical observa tions as described in the subject NTL and Form MMS-141 prior to commencing operations and prior to moving off location. The
observations will be documente d using Form MMS-141, or a facs imile and submitted along with videotapes, and any other imagery obtained, to the BOEMRE within 60 days after completion of the final ROV survey.

(h) Threatened and Endangered Species Information

Under Section 7 of the Endangered Species Act (ESA) all federal ag encies must ensure that any actions they authorize, fund, or carry out are not li kely to jeopardize the continued existence of a listed species, or destroy or adversely modify its designated critical habitat. In accordance with the 30 CFR 250, Subpart B, effective May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04, lessees/operators are require d to address site-specific information on the presence of federally listed threatened or endangere d species and critical habitat designated under the ESA and marine ma mmals protected under the Marine Mammal Protection Act (MMPA) in the area of proposes activities under this plan. Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer Continental Shelf; however, it is possible th at one or more of thes e species could be seen in the area of our operations. The following table reflects the Federally-listed endangered and threatened species in the lease ar ea and along the northern Gulf coast:Species Scientific Name Status Potential Presence Critical Habitat Designated in Gulf of Mexico Lease Area Coastal

Marine Mammals Sperm whale Physeter macrocephalus E X -- None

Florida manatee Trichechus manatus latirostris E -- X Florida ( Peninsular ) Blue whale B alaeno p tera musculus E X a -- None Fin whale B alaenoptera physalus E X a -- None Hum p back whale M e g a p tera novaean g liae E X a -- None North Atlantic right whale Eubalaena glacialis E X a -- None Sei whale B alaeno p tera borealis E X a -- None Sea Turtles Loggerhead turtle Caretta caretta T X X None Green turtle Chelonia m y das T, E b X X None Leatherback turtle Dermochelys coriacea E X X None Hawksbill turtle Eretmochel y s imbricata E X X None Kem p ’s ridle y turtle L e p idochel y s kem p ii E X X None Birds

Piping Plover Charadrius melodus T -- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E -- X Coastal Texas (Aransas National Wildlife Refu g e ) Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X Coastal Louisiana, Mississippi, Alabama, and Florida ( Panhandle ) Terrestrial Mammals Beach mice (Alabama, Choctawhatchee, Perdido Ke y , St. Andrew ) Peromyscus polionotus E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = Endangered; T = Threatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area. b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.



### The Environmental Impact Analysis in Section N of this plan further discusses potential impacts and mitigation measures related to threatened and endangered species.

(i) Archaeological Report

Sigsbee Escarpment Blocks 39 and 40 is not in an area designated as an area of high archaeological potential and, as such, an Archaeological Report is not required. NTL No. 2008-
G04.

(j) Air and Water Qu ality Information

This EP does not propose activities for which the State of Florida is an affect ed State. Therefore, the discussion required per NTL 2008-G04 is not applicable to this EP.

(k) Socioeconomic Information

The activities proposed in this pl an are not located offshore Florid a. Therefore, socioeconomic information required per NTL 2008-G04 is not applicable to this EP.

### F WASTE AND DISCH ARGE INFORMATION

The following estimates were prepared utilizing Anad arko’s experience with si milar drilling operations. Estimated maximum discharge rates are reflected below. Projected amounts may vary during the course of drilling operations.

(a) Projected Generated Wastes

Type of Waste Composition Projected Amount Treatment/Storage/Disposal Synthetic-based drilling fluids Synthetic-based drilling muds 16,000 bbls/well Re-use and/or transport to shore in tanks to Fourchon,
Louisiana and on to
base/transfer station. If recycled, returned to vendor (Bariod or MI). Cuttings wettedwith syntheticbased fluids Cuttings coated with synthetic drilling muds/fluids, including drilled

out cement 7,000 bbls/well Treated and discharge
overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting
boxes and on to the base/transfer station if oil still
remains

. Water-based drilling fluids Water based drilling muds (NaCl saturated,
seawater, freshwater, barite) 45,000 bbls/well Discharge overboard or at
seafloor

Cuttings wetted
with water-based
fluids Cuttings coated
with water-based drilling muds/fluids 2,000 bbls/well Discharge overboard

Chemical product waste (well treatment fluids) Ethylene glycol
Methanol 100 bbls/month
25 bbls/month Transport to shore in barrels to Fourchon, Louisiana for pick

up. Completion
Fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in barrels to Fourchon, Louisiana and on to Newpark Base. Non-pollutant completion fluids Low density
uninhibited completion brines 5,000 bbls/well Discharge overboard

Workover fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in barrels to Fourchon, Louisiana and on to Newpark Base. Trash Refuse generated during operations 50 bbls/month Transport to shore in disposal bags by vessel to shorebase for pickup by municipal operations. *Sanitary Wastes Treated human body waste 300,000/gals/well Chlorinate and discharge
overboard*Domestic Waste Gray water 300,000/ga ls/well Chlorinate and discharge
overboard Deck drainage Platform washings
and rainwater 210,000/bbls/well Treat for oil and grease and discharge overboard
Produced water N/A N/A N/A
Desalinization
Unit Seawater 21,000/bbl/well Discharge overboard

Wash water Drill water (fresh) 3,000 bbl/60 day
well Discharge overboard

Blowout preventer fluid Blend (3% Stack Magic & Filtered Fresh Water) 925 gals/week/well Discharge at seafloor

Ballast water Seawater As needed Discharge overboard Bilge water Seawater 685 bbls/well Discharge overboard through 15 ppm equipment
Excess cement at
the seafloor Nitrified cement slurry 1,200 bbls/well Discharge at seafloor

Fire water Seawater 137,142 bbl s/day Discharge overboard Cooling water Seawater 137,142 bbls/day Discharge overboard
Produced Sand N/A N/A N/A
Used oil Excess oil from engines 268.6 bbls/well Transport in totes to shore for recycling

(b) Projected Ocean Discharges

Type of Waste Total Amount to be Discharged Discharge Rate Discharge Method

*Sanitary Wastes 300,000/gals /well 25 gals per person daily Chlorinate and discharge
overboard *Domestic waste 300,000/gals /well 25 gals per person daily Chlorinate and discharge
overboard Deck drainage 210,000/bbls/well 3500 bbls/day Treat for oil and grease and discharge Blowout preventer
fluid 925 gals/week/well Vents on weekly
basis Discharge at seafloor

Desalinization Unit 21,000/bbl/well 350 bbls/day Discharge overboard Wash water 3,000 bbl/60 day
well 50 bbls/day Discharge overboard

Ballast water As needed Not continuous Discharge overboard Bilge water 685 bbls/well 317 bbls/da y Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor 1,200 bbls/well 20 bbls/min Discharge at seafloor

Fire water 137,142 bbls/day NA Discharge overboard Cooling water 137,142 bbls/day NA Discharge overboard Cuttings wetted with
Water-based fluids 2,000 bbls/well 1,000 bbls/hr max Discharge overboard

Water-based drilling
fluids 45,000 bbls/well 1,000 bbls/hr max Discharge at seafloor or
overboardCuttings wetted with Synthetic-based fluids 7,000 bbls/well NA Treated and discharge
overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil
still remains

. Non-pollutant completion fluids 5000 bbl/well 100 bbl/hour Discharge overboard

*The rig is designed for maximum personnel capacity of 200 people. The discharge rates are based off of maximum personnel capacity but will generally not have this many personne l onboard during drilling and/or completion operations.

(c) Modeling Report

The proposed activities under this plan do not meet the U.S. Environmental Protection Agency requirements for an individual NPDES permit. Th erefore, modeling report requirements per NTL No. 2008-G04 is not applicable to this EP.

### G AIR EMISSIONS INFORMATION

(a) Screening Questions

Screening Questions for EP’s Yes No Is any calculated Complex Total (CT) Emi ssion amount (in tons) associated with your proposed exploration activities more than 90% of the amounts calculated using the following formulas: CT = 3400D 2/3 for CO, and CT = 33.3D for the other air pollutants (where D = distance to shore in miles)? No

Do your emission calculations include any emission reduction measures or
modified emission factors? No

Are your proposed exploration activities located east of 87.5 W longitude? No Do you expect to encounter H2S at concentrations greater than 20 parts per million (ppm)? No

Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? No

Do you propose to burn produced hydrocarbon liquids? No



### (b) Emissions Worksheets

Air emissions worksheets have been prepared using a DP Drillship and DP Semisubmersible drilling units. Air emissions worksheets are available upon request. Pe r NTL No. 2008-G04, if an operator “answers no to all of the above screening questions from the appropriate table, provide”:

(1) “Summary information regarding the peak year emissions that will be generated by and associated with your Plan Emissions and Co mplex Total Emissions. This information is compiled on the summary form of the two sets of worksheets, and you can submit either these summary forms or the format below. You do not need to include the entire set of worksheets.”

(c) Summary Information

If drilled with a DP Semisubmersible:
Air Pollutant Plan Emission
Amounts 1 

### (tons) Calculated Exemption
Amounts 2 

### (tons) Calculated Complex Total
Emission
Amounts 3 

### (tons) Particulate matter (PM) 190.50 7425.90 N/A Sulphur dioxide (SO 2 

### ) 873.92 7425.90 N/A Nitrogen oxides (NO
x 

### ) 6548.42 7425.90 N/A Volatile organic compounds (VOC) 196.45 7425.90 N/A

Carbon monoxide (CO) 1428.75 125030.36 N/A

### If drilled with a DP Drillship:
Air Pollutant Plan Emission
Amounts 1 

### (tons) Calculated Exemption
Amounts 2 

### (tons) Calculated Complex Total
Emission
Amounts 3 

### (tons) Particulate matter (PM) 192.35 7425.90 N/A Sulphur dioxide (SO 2 

### ) 882.41 7425.90 N/A Nitrogen oxides (NO
x 

### ) 6612.10 7425.90 N/A Volatile organic compounds (VOC) 198.36 7425.90 N/A

Carbon monoxide (CO) 1442.64 125030.36 N/A

The air emission calculations were calculated by:

Jill Fowler Regulatory Analyst (832) 636-1554 jill.fowler@anadarko.com

### H OIL SPILL INFORMATION

(a) Oil Spill Response Planning

(i) OSRP Information

All the proposed activities and facilities in this EP are covered by the Regional Oil Spill Response Plan (OSRP) approved on June 24, 2009 a nd the Oil Spill Response Certification letter accepted by BOEMRE on July 27, 2011 for An adarko Petroleum Corporation and its subsidiaries, Kerr-McGee Oil & Gas Corporation and Anadarko E&P Company L.P. (Company Numbers 00981, 02219 and 00148, respectivel y) in accordance with 30 CFR Part 254. Anadarko submitted a revision to its Regional OSRP on July 21, 2011 updating the exploratory WCD to Garden Banks Block 346. The revision is pending approval.

(ii) Spill Response Sites

Primary Response Equipment Location(s) Preplanned Staging Location(s) 

### Houma, Louisiana Harvey, Louisiana Venice, Louisiana Lake Charles, Louisiana Galveston, Texas Fourchon, Louisiana Harvey, Louisiana Venice, Louisiana Cameron, Louisiana Galveston, Texas

(iii) OSRO Information

Anadarko’s primary equipment provider is Clea n Gulf Associates (CGA). Personnel would be obtained from the Marine Spill Response Corpor ation’s (MSRC) STARS network, including a supervisor to operate the equipment.

In addition Anadarko has a contract with Nati onal Response Corporation (NRCC) for additional equipment. NRCC’s Independent Contractor Ne twork (ICN) will provide the closest available personnel and additional equipment as needed.

Anadarko is a member of the Helix Well Cont ainment Group (HWCG), a combination of the Helix Fast Response System (HFRS) and the co mmon equipment and services. This agreement
allows access to subsea well contai nment and well shut-in equipment.

Anadarko is also a member of the Marine Well Containment Co mpany (MWCC), which provides access to containment response capabilities and includes subsea dispersant injection equipment.

### (iv) Worst-Case Scenario Determination

Category Regional OSRP EP EP Type of Activity Exploratory Exploratory Exploratory Facility Location GB 346 SE 39 SE 40 Facility Designation * GB 346 “A” SE 39 “B” SE 40 “C”

Distance to Nearest 118 miles 223 miles 223 miles Storage Tanks (total) N/A N/A N/A Flowlines (on facility) N/A N/A N/A Pipelines N/A N/A N/A Uncontrolled Blowout 350,000 bopd** 256,561 bopd 226, 188 bopd Type of Oil(s) Oil Oil Oil API Gravity 30.1 o 21 o 21 o

* Note–for the OSRP exploratory worst case discharge scenario only the Area/Block is referenced in the OSRP. Exploratory drilli ng facility designations (proposed well location names) are typically not included in the OSRP.

** The volume denoted in the Regional OSRP is higher than the NTL No. 2010-N06 (256,700 bopd) and BOEMRE (321,108 bopd) calculations. Anadarko elected to denote a higher volume in the Regional OSRP for planning purposes to demonstrate equipment respons e capabilities per previous disc ussions with Rusty Wright.



### Anadarko has determined that the worst-case scenar ios from the activities pr oposed in this Initial EP do not supersede the worst-case s cenario for Garden Banks Block 346.

Since Anadarko has the cap ability to respond to the worst-case spill s cenario included in our Regional OSRP, and since the worst-case scenario s determined for our EP does not replace the worst-case scenario in our revised Regional OSRP submitted on July 21, 2011, I hereby certify that Anadarko has the capability to respond, to th e maximum extent practicable, to a worst-case discharge, or a substantial threat of such a discha rge, resulting from the ac tivities proposed in our
EP.

(b) Worst-Case Discharge Volume Assumptions

Worst-case discharge (WCD) calculations and assump tions within this section utilized guidelines and requirements pursuant with NTL No. 2010-N 06. The following information summarizes the WCD scenario for Sigsbee Escar pment Blocks 39 and 40:

Discussions regarding geologic information are considered proprietary and have been omitted from this public copy EP.

(c) Oil Spill Response Discussion

For the purpose of NEPA analys is, the largest spill volume or iginating from the proposed activity would be an uncontro lled blowout of the well duri ng drilling operations at 256,561 BOPD with an API gravity of 21 ° . A discussion of the blowout scenario from this proposed activity is included within this Initia l EP in accordance with NTL No. 2010-N06.

### Land Segment and Resource Identification Modeling

Trajectory of a spill and the probability of its impacting a land segment have been projected utilizing information in the Oil Spill Risk An alysis Model (OSRAM) fo r the Western Gulf of Mexico. Additional information may be referenced in the “Oil-Spill Risk Analysis: Contingency Planning Statistics for Gulf of Mexico OC S Activities” (OCS Report MMS 2004-026), using the average conditional probability for 3, 10, and 30 day impacts.

Sigsbee Escarpment 39 is located within La unch Area 29. According to the OSRAM, the trajectory indicates a 2% probability of potential impact to the shoreline in Matagorda County and/or Galveston County in Texas and/or Cameron Parish in Louisiana. The results are shown in
Table H-2.

Matagorda County, Galveston County and/or Cameron Parish are identified as the most probable potential impacted county or pa rish within the Gulf of Mexico for this operation. Matagorda County is located Texas and includes Big Bo ggy NWR, a portion of San Bernard NWR, and Mad Island Wildlife Management Area (WMA). Galv eston County is also located in Texas and includes Galveston Island State Park, Brazoria Na tional Wildlife Refuge (NWR), Apffel Park, Seawolf Park, Old Fort Travis Park, Atkinson Island WMA, Ft . Anahuac Park, Anahuac NWR,
and McFaddin NWR. Cameron Parish is locate d in Louisiana and in cludes Cameron Prairie NWR, East Cove Unit (a part of the Cameron Prairie NWR), Lacassine NWR, and Sabine NWR.

Response

Anadarko will make every effort to respond to the worst-case discharge as effectively as possible. Response equipment available to respond to the worst-case discharge and the estimated time of a spill response from oil spill detecti on to equipment deployment on-site is included in
Table H-3. The table estimates individual times n eeded for procurement, load out, travel time to the site and deployment. In the event of an actual incident equipment and times can vary.

For the purpose of response scenario discussion, an uncontrolled blowout of the well would be considered the largest potential spill vol ume at 256,561 BOPD. An AD IOS weathering model was run based on a similar type of oil expected to be produced from this well. Based on this information, approximately 9% (23,090 bbl s) of the initial volume would be evaporated/dispersed within 24 hours.

If approved and appropriate, 4 sorties (8,000 ga llons) from the Basler ai rcraft and 8 sorties (9,600 gallons) from two DC-3 aircrafts could disperse approximately 7,540 barrels of oil.

If the conditions are appropriate, and the necessary approvals and permits have been obtained, in-situ burning may be utilized. Based on in -situ burn operations du ring Deepwater Horizon, approximately 5% (11,674 bbls) of the wo rst case discharge volume after natural evaporation/dispersion coul d potentially be burned.

Although unlikely in a spill lastin g 30 days, potential shoreline impact in Galveston and/or Matagorda County, and/or Camer on Parish could occur depending on environmental conditions

### (wind, currents and temperature) at the time of an incident. N earshore response may include the use of shoreline boom on beach areas, or pr otection/sorbent boom on vegetated areas. Surveillance and real time trajectories would aide in determining the most appropriate strategies to respond to a spill.

Table H.3 provides an example of offshore a nd nearshore equipment, response times, and personnel to respond to a spill of 233,471 BOPD, which is the estimated amount that would remain considering natural evaporation/dispersi on at 24 hours. This amount could be further reduced through the applicat ion of aerial and subsea dispersants, provided su ch applications were approved.

Anadarko’s contingency plan for de aling with this worst-case disc harge would be to activate its Spill Management Team and equipment resources as described in its Gulf of Mexico Regional Oil Spill Response Plan (OSRP) and provide con tinuous support for the duration of the event. Response resources are activated and supplemen ted according to need. These resources would remain engaged in the response until the incident is deemed complete or until released by
Unified Command.

Anadarko is a member of the Helix Well Cont ainment Group (HWCG), a combination of the Helix Fast Response System (HFRS) and the co mmon equipment and services. This agreement
allows access to subsea well contai nment and well shut-in equipment.

Anadarko is also a member of the Marine Well Containment Co mpany (MWCC), which provides access to containment response capabilities and includes subsea dispersant injection equipment.

In the event of a blowout, Anadarko may:

1. Evacuate personnel, if necessary. Deploy emer gency responders in an effort to preserve human life, if necessary.

2. Assess the damage and attempt to stop the flow at the source, if safe to do so, to reduce the amount of oil discharged.

3. Notify agencies.

4. Assess the amount of oil that has been sp illed and calculate add itional potential of oil flow. A continuous aerial surveillance program w ould be used to assess the growth of the
slick and the volume of oil on the water. Ob servations of the si ze of the slick on the water, combined with observations at the s ource, would be used to provide a constant update. Additional potential to release fuel from the remaining tanks onboard the dynamically positioned (DP) semi-submersible drilling rig would be determined by marine surveyors. Operations and Unifie d Command would continue to assess the adequacy of response equipment capacities based on this continually updated mass
balance.

### 5. Convene the Spill Management Team (SMT ). Organize Unified Command and establish objectives and priorities.

6. Monitor the oil spill with aerial surveillance and obtain tr ajectories. If oil is seaward bound, going away from land, discuss additiona l strategies with Unified Command.

7. If oil is moving in the direction of a shoreline and weather co nditions are favorable, request approval to u tilize dispersants.

a. Prior to commencing application operati ons, conduct an on-site survey in consultation with natural resource specialists to determ ine if any threatened or endangered species are present in the projected application ar ea or otherwise at risk from dispersant application.

b. Upon approval, mobilize one Basler aircraft and two DC-3 aircrafts from Houma, with surveillance aircraft and spotter. Rotate airc raft, spraying the leading edge of the spill and working back to the source. Monitor/sample for effectiveness (USCG SMART Team). Truck additional dispersants from CGA stockpile to Houma, if necessary.

c. Dispersants are most effective when app lied as soon after discha rge as possible, since weathering of the oil decreas es dispersant effectiveness. The estimated window of opportunity for most effectiv e use of dispersants is w ithin 48-72 hours post-release. The oil may still be dispersible after 72 hours on the water surface, but the effectiveness of dispersant use would likely be diminished after th e oil has been on the water for more than three days. Ultimat ely, the USCG SMART monitoring protocol will be used to determine whether or not dispersant operations are effective.

d. Once the CGA HOSS barge is on locati on and in the skimming mode, dispersants would only be used if required and approved.

8. Deploy offshore mechanical oil containment and recovery equipment. Attempt to recover
as much oil at sea as possible, utilizing:

a. The CGA HOSS barge, will be positioned in a stationary mode, will be situated downwind and down-current from location fo r long-duration, high-volume skimming. Based on average travel times, the HO SS barge could be on location within approximately 47.5 hours of the release. The de-rated skimming capacity of the HOSS barge is 43,000 bbls per day. However, only the oil encountered by a skimmer can be
recovered. In order to maximize oil encount er rate, boom will be deployed in a V-configuration in front of the HOSS barge to funnel oil to the skimmers. If necessary, temporary barges can be ac tivated to support continuous skimming operations. (These barges arrive on-site at approximately the same time as the HOSS barge.) For an on-going release, multiple barges are deployed to provide for continuous off-loading of skimmer storage vess els and shuttling of recovered oil to an onshore waste handling facility. Sufficient barges are available to provide enough temporary storage for continuous recovery operations.

### b. CGA’s Fast Response Units (FRU) woul d arrive on-scene between approximately
21.25-27.25 hours of the initial re lease. These skimmers operate downstream of the HOSS barge and are used to recover pockets and streamers of oil that may move past the large stationary skimmer. Each FR U has 200 barrels of on-board storage. Approval will be requested to decant wate r after gravity separation, through a hose forward of the skimmer, to optimize tempor ary storage capacity. A 42" Boom will be
utilized to concentrate oil so that it is thic k enough to be skimmed.

9. Dispersants, Fast Response Units (FRU), Oil Spill Response Vessels (OSRV or R/V) would typically work daylight hours onl y. The HOSS barge can operate continuously, including night operations. Available technology will be considered such as remote sensing devices that will enable 24 hour surveillance, trajecto ries, and planning. All response vessels are designed to be able to remain offshore continuously throughout the response. Even if sea conditions prohibit effective skimming, these resources would remain offshore until skimming operations c ould be commenced again. Safety would remain the first priority.

10. Prepare Site-Specific Waste Management Pla n, Site Safety Plan, Decontamination Plans,
Communications and Medical Plans.

11. If oil becomes a threat to any shoreline, da ta from the aerial survei llance, weather reports, and trajectories would be used to direct onshore teams to deploy protection/containment boom with reference to Area Contingency Pl ans and in coordination with State and
Federal On-Scene Coordinators.

a. Implement pre-designated strategies.

b. Identify resources at risk in spill vicinity.

c. Develop/implement appropriate protection tactics.

12. Establish Site-Specific Wildlif e Rescue and Rehabilitation Plan.

### The following types of additional support may be required for a blowout lasting 120 days.

 Additional Oil Spill Remova l Organization (OSRO) personnel to relieve equipment operators

 Vessels for supporting offshore operations

 Field safety personnel

 Continued surveillance and m onitoring of oil movement

 Helicopter, video cameras

 Infra red (night time spill track ing) capabilities, X-band radar

 Barge to transport recovered oil from offshore skimming system, and temporary storage barges to onshore disposal sites th at are identified in Area Contingency Plans (ACP)

 Logistics needed to support equipment:

- Staging areas

- Parts, trailers, and mechanics to maintain skimmers and boom

- Fueling facilities

- Decontamination stations

- Dispersant stockpile tran sported from Houston to Houma or other potential command post locations

- Communications equipm ent and technicians

 Logistics needed to s upport responder personnel

- Medical aid stations

- 

### Safety personnel

- Food

- Berthing

- Additional clothing/safety supplies

- Decontamination stations

Louisiana CZM Containment Response Information
Anadarko has the capability to respond and cont ain, to the maximum extent practicable as defined in 30 CFR 254.6 and 30 CFR 250.26(d)(1), to the estimated wors t case discharge (WCD) associated with the proposed activity within 30 days. Deployment time for surface containment equipment is subject to availability and loca tion, weather conditions, potential security zones around the spill site, and site/well specific assessment data. Personnel safety is always first and
foremost. Refer to further detail s on equipment and timing provided in Section H–Oil Spill
Information and Table H-3 of the EP.

The potential WCD will be further evaluated du ring the Application for Permit to Drill (APD) process, including the Well Containment Screen ing Tool (WCST) and associated subsea containment plan for enhanced planning purposes.

There will be no new or unusual technology deployed that has not been previously deployed for Gulf of Mexico oil spill prev ention, control, and/or cleanup.Table H-1

Worst Case Discharge Calculation (Based on Blowout during Drilling Operations)

Calculations for Uncontrolled Blowout> 10 miles from shore: Block 39

i. Type of Oil (crude, condensate, diesel) Crude

ii. API Gravity 21 o

iii. EP Location Used for NTL No. 2010-N06 WCD for SE 39 IEP location “B”

iv. Largest Anticipated WCD Rate during blowout 256,561 BOPD

v. WCD Total for Drilling Operations for SE 39(> 10 miles from shore): 256,561 BOPDTable H-2

Trajectory by Land Segment

Following are the average conditional probabilities (expresse d as percent chance) that an oil spill starting at a particular launch area will contact a la nd segment as included in the Oil Spill Risk Analysis Model (OSRAM) for the Central and Western Gulf of Mexico. This information can be found on the BOEMRE website using 3/10/30 day potential impact, as applicable. The results are listed below.

Area/Block OCS-G Launch
Area Land Segment and/or Resource Conditional Probability (%)

3 days 10 days 30 days

Sigsbee Escarpment

Block 39

Drilling (223 miles from shore) G27779 LA 29

Western Planning

Area Kenedy County, TX Kleberg County, TX Aransas County, TX Calhoun County, TX Matagorda County, TX Brazoria County, TX Galveston County, TX Jefferson County, TX Cameron Parish, LA Vermilion Parish, LA --

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1Table H-3WCD Scenario Drilling Activities – Based on a singlewell uncontrolled blowout (223 miles from shore)Sigsbee Escarpment 39 (Location “B”)256,561 BOPD (initial volume)233,471(after evaporation/dispersion)API Gravity 21Offshore Equipment from Spill Detection to Equipment Deployment Response Time: Sigsbee Escarpment 39Offshore EquipmentOwner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander--------122ASI/Houma Houma001111.7503.75HOSS BargeOperatorsTugs43,000 4,000 183CGA/HarveySTARSVOOHarvey1244042.5147.5OSRB ValiantOperatorsTugs24,000 20,892 161NRCC/Aransas PassICNVOOAransas Pass0221457163OSRB DefenderOperatorsTugs24,000 16,500 161NRCC/Bayou La BatreICNVOOBayou La Batre0221464170OSRB EnergyOperatorsTugs1,512 300 141NRCC/Morgan CityICNVOOMorgan City0221426.5132.5FRUOperatorsUtility Boat3,770 200 161CGA/InglesideSTARSVOOIngleside0221223.25127.25FRUOperatorsUtility Boat3,770 200 161CGA/GalvestonSTARSVOOGalveston0221219123FRUOperatorsUtility Boat3,770 200 161CGA/Lake CharlesSTARSVOOCameron.5221220.25124.25FRUOperatorsUtility Boat3,770 200 161CGA/Morgan CitySTARSVOOMorgan City.5221217.75121.75FRUOperatorsUtility Boat3,770 200 161CGA/HarveySTARSVOOHarvey.5221220124FRUOperatorsUtility Boat7,540 400 2122CGA/LeevilleSTARSVOOLeeville.5221217.25121.25Spill Team Area Responders (STARS) called out by Marine Spill Response Corporation (MSRC)Independent Contractor Network (ICN) calledout by National Response Corporation (NRCC)Vessel of Opportunity=VOOEMS=Enterprise Marine ServicesK-Sea=K-Sea Operating PartnershipOffshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsFRUOperatorsUtility Boat7,540 400 2122CGA/VeniceSTARSVOOVenice0221218.75122.75Koseq Skimming ArmsOperatorsVessel w/ storage/hull89,145 2,500 5 sets305CGA/GalvestonSTARSVOOGalveston02211219133Koseq Skimming ArmsOperatorsVessel w/ storage/hull53,487 1,500 3 sets183CGA/LeevilleSTARSVOOLeeville02211217.25131.25Koseq Skimming ArmsOperatorsVessel w/ storage/hull17,829 500 1 set61CGA/FourchonSTARSVOOFourchon02211216.25130.25Koseq Skimming ArmsOperatorsVessel w/ storage/hull35,658 1,000 2 sets122CGA/VeniceSTARSVOOVenice02211218.75132.75DBL 101OperatorsTugs-- 107,285 1204K-Sea/Atlantic Venice0242460167DBL 102OperatorsTugs-- 107,285 1204K-Sea/Atlantic Venice0242460167CTCo2605OperatorsTug-- 20,000 161EMS/Amelia Amelia0244044149CTCo 5001OperatorsTug-- 47,000 161EMS/Amelia Amelia024404414910,000' 42" Auto BoomVOO-- -- 4020 crewCGA/HarveySTARSHarvey.5212201245,000' 42" Auto BoomVOO-- -- 2010 crewCGA/Lake CharlesSTARSCameron.521220.25124.255,000' 42" Auto BoomVOO-- -- 2010 crewCGA/GalvestonSTARSGalveston0212191232,500' 42" Auto BoomVOO-- -- 126 crewCGA/InglesideSTARSIngleside021223.25127.252,500' 42" Auto BoomVOO-- -- 126 crewCGA/PascagoulaSTARSPascagoula021224.5128.52,700' 42" BoomVOO-- -- 126 crewNRCC/Aransas PassICNAransas Pass0212231274,000' 42" BoomVOO-- -- 168 crewNRCC/Corpus ChristiICNCorpus Christi021223.75127.751,000' 42" BoomVOO-- -- 63 crewNRCC/Bayou La BatreICNBayou La Batre021225.5129.5Offshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/Persons300' 42" BoomVOO-- -- 21 crewNRCC/Morgan CityICNMorgan City021217.75121.7522,400' 42" BoomVOO-- -- 8025 crewAMPOL/New Iberia New Iberia021218.75122.754,800' 42" BoomVOO-- -- 189 crewAMPOL/Harvey Harvey021220124Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/FourchonPHI/FourchonSTARSSpill SiteSpill SiteFourchon111.5111.5------2.52.53------3.53.54.5Total 322,561 330,562Nearshore Equipment from Spill Detection to Equipment Deployment Response Time:Sigsbee Escarpment 39Nearshore Equipment*Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander----122ASI/Houma Houma00111.7502.75OSRV AdmiralOperators24,000 300 16NRCC/GalvestonICNGalveston021230134OSRV LibertyOperators24,000 300 16NRCC/MiamiICNMiami021467173SWS EgmopolOperators3,000 100 13CGA/GalvestonSTARSGalveston021250053SWS EgmopolOperators3,000 100 13CGA/Morgan CitySTARSMorgan City.521217020SWS MarcoOperators3,588 34 13CGA/LeevilleSTARSLeeville.5212609SWS MarcoOperators3,588 20 13CGA/Lake CharlesSTARSCameron.521236039SWS MarcoOperators3,588 34 13CGA/VeniceSTARSVenice.52121301656' Nearshore SkimmerOperators21,500 250 14CGA/Morgan CitySTARSMorgan City.521217020R/V Grand BayOperators5,000 65 13CGA/VeniceSTARSVenice.522.5406.5R/V RW ArmstrongOperators5,000 65 13CGA/LeevilleSTARSLeeville.522.5204.5R/V Bastian BayOperators5,000 65 13CGA/Lake CharlesSTARSCameron.522.59.5012R/V Timbalier BayOperators5,000 65 13CGA/GalvestonSTARSGalveston022.513015.5CTCo2603OperatorsTug-- 25,000 161EMS/Amelia Amelia0244015120CTCo 2604OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244015120CTCo 2606OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244015120CTCo 2607OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244015120CTCo 2608OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244015120Nearshore Equipment, cont.*Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsCTCo 2609OperatorsTugs-- 23,000 161EMS/Amelia Amelia02440151208-Band Rope MopUtility Boat2,283 100 1/41NRCC/GalvestonVOOGalveston0212200234-Band Rope MopUtility Boat1,509 100 1/41NRCC/Morgan CityVOOMorgan City02126.7509.75Vikoma CascadeUtility Boat5,520 100 1/41NRCC/HoustonVOOGalveston021255.5058.5Vikoma CascadeUtility Boat5,520 100 1/41NRCC/SulphurVOOSulphur021238.5041.52,000' Beach Boom -- -- 6 CGA/Galveston Galveston 0 1 2 20 2 251,000' Beach Boom -- -- 4 CGA/Ingleside Ingleside 0 1 2 30.5 2 35.52,000' Beach Boom -- -- 6 CGA/Pascagoula Pascagoula 0 1 2 10.5 2 15.510,000' 18" BoomVOO-- -- 10/41Oil Mop/New Iberia New Iberia02119.25314.2510,000' 18" BoomVOO-- -- 10/41Oil Mop/Houston Houston121122.5327.510,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Arthur Port Arthur02111732210,000' 18" BoomVOO-- -- 104 crewOil Mop/Houma Fourchon.5211531010,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Allen Port Allen0211931420,000' 18" BoomVOO-- -- 208 crewOil Mop/Belle Chasse Venice.52115.5613.515,000' 18" BoomVOO-- -- 146 crewOil Mop/Gretna Gretna02115.5411.5Wildlife Support Trailer -- -- 1/ 2 crew CGA/Harvey Harvey .5 1 2 2 3 8Bird Scare Cannons -- -- 2 CGA/Venice Venice .5 1 2 3.5 2 8.5Bird Scare Cannons -- -- 1CGA/Galveston Galveston .5 1 2 6.5 2 11.5Bird Scare Cannons -- -- 1CGA/Ingleside Ingleside .5 1 2 10 2 15Bird Scare Cannons -- -- 2CGA/Lake Charles Cameron .5 1 2 5 2 10Bird Scare Cannons -- -- 2CGA/Pascagoula Pascagoula .5 1 2 3.25 2 8.25Bird Scare Cannons -- -- 2CGA/Harvey Harvey .5 1 2 2 2 7Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/FourchonPHI/FourchonSTARSSpill SiteSpill SiteFourchon111.5111.5------.5.53------1.51.54.5Total 121,096 135,798*Some equipment may be used offshoreup to approximately 25 miles from shoreH-3 (continued)

Operational Limitations of Response Equipment

 HOSS Barge–8 foot seas

 Fast Response Unit (FRU)–8 foot seas

 Oil Spill Response Vessel (OSRV and R/V)–4 foot seas

 Boom–3 foot seas, 20 knot winds

 Dispersants–winds more than 25 knots, visibility less than 3 nautical miles or ceiling less than 1,000 feet

### I Environmental Monitoring and Envi ronmental Mitigation Measures

(a) Monitoring

If required, Anadarko will monitor loop currents per NTL 2005-G05.

Anadarko subscribes to Wilkins Weather Service which provides real-time weather conditions such as tropical depressions, st orms and/or hurricanes entering the Gulf.

(b) Incidental Takes

Although marine mammals may be seen in the area, Anadarko does not believe that its operations proposed under this EP will result in the harassment, capture, collection or killing of any mammals covered by th e Marine Mammal Protection Act.

Anadarko will operate in accordance with applicable regulations, including:

NTL No. 2007-G02 – “Implementation of Se ismic Survey Mitigation Measures and Protected Species Observer Program”
NTL No. 2007-G03 “Marine Trash and De bris Awareness and Elimination”, and
NTL No. 2007-G04 “Vessel Strike Avoidan ce and Injured/Dead Protected Species Reporting”

### J LEASE STIPULATIONS INFORMATION

Lease Sale #196:

-Stipulation No. 5- Protected Species:

This stipulation requires operators to collect and remove flotsam resulting from their activities; to post signs detailing why release of debris must be eliminated; watch for protected marine mammals and see turtles (includes speed and distance parameters if mammals or turtles are sited); reports sightings and locations of dead or injured marine mammals or turt les and if the operators activities are responsible remain available to assist in the recovery and comp ly with applicable mitigation measures when conducting seis mic operations. It also requires operators to comply with applicable No tices to Lessees which contain further restrictions regarding protection of marine mammals and turtles.

### K Support Vessels and Aircraft Information

(a) General

Type Max. Fuel Tank Storage Capacity Max. No. in Area at any Time Trip Frequency or
Duration Supply Vessel 3500 gallons 1 2 trips/week Helicopter 280 gallons 1 7 trips/week Crew Vessel 1500 gallons 1 3 trips/week Tug Boat N/A N/A N/A

(b) Diesel Oil Supply Vessels

Fuel for the rig will be transpor ted via a supply vessel as follows:

a. Size of fuel supply vessel: 230 feet

b. Carrying capacity of fu el supply vessel: 309,270 gallons
c. Frequency that fuel supply vessel will visit the
facilities: once per week

d. Routes the fuel supply vessel will use to travel between the onshore support base and proposed facility: 6 miles from Port Fourchon to the mouth of Bayou Lafourche, then approximately 237
miles to SE 39 & 40.



### (c) Vicinity Map

A vicinity map is included in this section as Attachment K-1.

(d) Solid and Liquid Wastes Transportation

Type of
Waste Composition Total Projected
Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or mud Syntheticbased drilling
muds 128,000 bbls 16,000 bbls/well Re-use
and/or transport to shore in
tanks. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer Station. If recycled,
returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection dipsosal facility) or USLL (landfarm).Cuttings
wetted withsyntheticbased muds Cuttings
coated with synthetic drilling muds, including
drilled out

cement 2,800-5,600
bbls 350-700
bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
tanks and/or cutting
boxes. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer Station. If recycled,
returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 4,000 bbls

1,000 bbls 100 bbls/month

25 bbls/month Transport to shore in
drums
and/or tote
tanks for pick up Chemwaste in Sulphur,
LA and Veolia Port Arthur, TX or to Newpark, Port Arthur
as non-hazardous waste. Can be returned to
vendor and/or used at another facility;
MEG is solidified and disposed of in
a landfill.
Methanol is
incinerated or used for fuels blending. Completion
fluids Brine, spent acid, prop sand, debris 24,000 bbls 3,000 bbls/well Transport to
shore in cuttings boxes, drums,
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer
Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand, debris 24,000 bbls 3,000 bbls/well Transport to
shore in cuttings boxes, drums,
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer
Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Trash and
debris Refuse generated during operations 2,000 bbls 50 bbls/month Transport to
shore in disposal bags by
vessel to
shorebase for pickup by municipal operations Recycled Material in ARC, New Iberia, LA. Trash disposed of at
SWDI landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 4,300 bbls 430 bbls/120 days Transport in

totes to shore for pick up American Recovery Fourchon, LA Recycled

*Total amount assumes 8 wells at 150 days/wellSigsbeeEscarpmentBlocks39and40June2011EnvironmentalImpactAnalysisforInitialExplorationPlanPage2Figure1.Vicinitymapfortheleasearea.

### L ONSHORE SUPPORT FACILITIES INFORMATION

(a) General

Per NTL No. 2008-G04, the following tables re flect the onshore facilities Anadarko will utilize to provide supplies and service support for the activities proposed in this Exploration Plan.

Name Primary Location Existing/New/Modified Anadarko Service Base Fourchon, Louisiana Existing

Name *Alternate Locations Existing/New/Modified Anadarko Service Base Galveston, TX Existing Anadarko Service Base Cameron, LA Existing Anadarko Service Base Pascagoula, MS Existing

*In the unlikely event Anadarko’s prim ary service base cannot be utilized
Anadarko will exercise the use of an alt ernate service base during drilling and/or completion operations.

(b) Support Base

No support base construction or expans ion is planned for these activities.

(c) Waste Disposal

Disposed wastes describe those wastes ge nerated by the proposed activity that are disposed of by means other than by release in to the water of the GOM at the site where they are generated. These wastes can be disposed of by offsite release, injection, encapsulation, or placement at either onshor e or offshore permitted locations for the purposes of returning them back to the environment.

Type of
Waste Composition Total Projected
Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or mud Syntheticbased drilling
muds 128,000 bbls 16,000 bbls/well Re-use
and/or transport to shore in
tanks. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer Station. If recycled,
returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection dipsosal facility) or USLL (landfarm).Cuttings
wetted withsyntheticbased muds Cuttings
coated with synthetic drilling muds, including
drilled out

cement 2,800-5,600
bbls 350-700
bbls/well*

*An estimated 5-10% of cuttings may be transported to
shore Re-use and/or transport to shore in
tanks and/or cutting
boxes. Waste - Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer Station. If recycled,
returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t
be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility) or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 4,000 bbls

1,000 bbls 100 bbls/month

25 bbls/month Transport to shore in
drums
and/or tote
tanks for pick up Chemwaste in Sulphur,
LA and Veolia Port Arthur, TX or to Newpark, Port Arthur
as non-hazardous waste. Can be returned to
vendor and/or used at another facility;
MEG is solidified and disposed of in
a landfill.
Methanol is
incinerated or used for fuels blending. Completion
fluids Brine, spent acid, prop sand, debris 24,000 bbls 3,000 bbls/well Transport to
shore in cuttings boxes, drums,
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer
Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand, debris 24,000 bbls 3,000 bbls/well Transport to
shore in cuttings boxes, drums,
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer
Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer
Station Port Arthur.
USLL Galveston and
Fourchon Transfer
Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is transferred to Newpark's Processing & Transfer facility for injection.
Trash and
debris Refuse generated during operations 2,000 bbls 50 bbls/month Transport to
shore in disposal bags by
vessel to
shorebase for pickup by municipal operations Recycled Material in ARC, New Iberia, LA. Trash disposed of at
SWDI landfill. Recycled and/or disposed in
landfill.

Used oil Excess oil from engines 4,300 bbls 430 bbls/120 days Transport in

totes to shore for pick up American Recovery Fourchon, LA Recycled

*Total amount assumes 8 wells at 150 days/well

### M COASTAL ZONE MANAGEM ENT ACT INFORMATION

Issues identified in the Louisiana Coas tal Zone Management Program include the following: general coastal use guidelines, levees , linear facilities (pipelines); dredged soil deposition; shoreline modifications, surf ace alterations, hydrologic and sediment transport modifications, waste disposal; uses that result in the alteration of waters draining into coastal waters; oil, gas, or other mineral activitie s; and air and water quality.

Relevant enforceable policies were considered in certifying consistency for Louisiana.

### N ENVIRONMENTAL IMPACT ANALYSIS

# Environmental Impact Analysis

INITIAL EXPLORATION PLAN Sigsbee Escarpment Block 39 ( OCS

- G 2 7779 ) Sigsbee Escarpment Block 40 ( OCS

- G 27780 )

Offshore Louisiana

June 2011

Prepared for:

Jill Fowler Regulatory Analyst
Anadarko Petroleum Cor poration
1201 Lake Robbins Drive The Woodlands, Texas 77380

Telephone (832) 636

- 1554

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997 Telephone: (772) 219

- 3000Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page ii 

## Contents

Page



### Introduction

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

A. Impact

- Producing Factors

................................ ................................ ....................... 5

A.1 Drilling Rig Presence (including noise and lights)

................................ ................................ .......... 5

A.2 Physical Disturbance to the Seafloor

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

A.3 Air Pollutant Emissions

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

A.4 Effluent Discharges

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

A.5 Water Intake

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

A.6 Onshore Waste Disposal

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

A.7 Marine Debris

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

A.8 Support Vessel and Helicopter Traffic

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

A.9 Accidents

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

A.9.1 Types of Accidents Evaluated

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

A.9.2 Small Fuel Spill

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

A.9.3 Crude Oil Spill (Worst Case Discharge)

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

A.9.4 Other Accidents Not Analyzed in Detail

................................ ................................ .......... 16



### B. Affected Environment

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

C. Impact Analysis

................................ ................................ ................................ ..... 19

C.1 Physical/Chemical Environment

................................ ................................ ................................ .. 19

C.1.1 Air Quality

................................ ................................ ................................ ........................ 19

C. 1.2 Water Quality

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

C.2 Seafloor Habitats and Biota

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

C.2.1 Soft Bottom Benthic Communities

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

C.2.2 High

- Density Deepwater Benthic Communities

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

C.2.3 Designated Topographic Features

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

C.2.4 Pinnacle Trend Area Live Bottoms

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

C.2.5 Eastern Gulf Live Bottoms

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

C.3 Threatened, Endangered, and Protected Species and Cri tical Habitat

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

C.3.1 Sperm Whale (Endangered)

................................ ................................ ............................ 31

C.3.2 West Indian Manatee (Endangered)

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

C.3.3 Endangered Mysticete Whales

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

C.3.4 Non

- Endanger ed Marine Mammals (Protected)

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

C.3.5 Sea Turtles (Endangered/Threatened)

................................ ................................ ............ 39

C.3.6 Piping Plover (Threatened)

................................ ................................ .............................. 42

C.3.7 Whooping Crane (Endangered)

................................ ................................ ....................... 44

C.3.8 Gulf Sturgeon (Threatened)

................................ ................................ ............................. 44

C.3.9 Beach Mice (Endangered)

................................ ................................ ................................ 45

C.4 Coastal and Marine Birds

................................ ................................ ................................ ............ 46

C.4.1 Marine Birds

................................ ................................ ................................ .................... 46

C.4.2 Shorebird s and Coastal Nesting Birds

................................ ................................ .............. 48

## Contents
( C ontinued)

Page

Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmenta l Impact Analysis for Initial Exploration Plan Page iii C.5 Fisheries Resources

................................ ................................ ................................ ..................... 51

C.5.1 Pelagic Communities and Ichthyoplankton

................................ ................................ ..... 51

C.5.2 Essential Fish Habitat

................................ ................................ ................................ ....... 53

C.6 Archa eological Resources

................................ ................................ ................................ ............ 56

C.6.1 Shipwreck Sites

................................ ................................ ................................ ................ 56

C.6.2 Prehistoric Archaeological Sites

................................ ................................ ...................... 57

C.7 Coastal Habitats and Protected Areas

................................ ................................ ......................... 58

C.8 Socioecono mic and Other Resources

................................ ................................ .......................... 61

C.8.1 Recreational and Commercial Fishing

................................ ................................ ............. 61

C.8.2 Public Health and Safety

................................ ................................ ................................ .. 63

C.8.3 Employment and Infrastructure

................................ ................................ ...................... 64

C.8.4 Recreation and Tourism

................................ ................................ ................................ .. 64

C.8.5 Land Use

................................ ................................ ................................ .......................... 65

C.8.6 Other Marine Uses

................................ ................................ ................................ .......... 66



### D. Environmental Hazards

................................ ................................ ......................... 67

D.1 Geologic Hazards

................................ ................................ ................................ ......................... 67

D.2 Severe Weather

................................ ................................ ................................ ........................... 67

D.3 Currents and Waves

................................ ................................ ................................ .................... 67



### E. Alternatives

................................ ................................ ................................ .......... 67

F. Mitigation Measures

................................ ................................ ............................. 67

G. Consultation

................................ ................................ ................................ ......... 68

H. Preparers

................................ ................................ ................................ .............. 68

I. References

................................ ................................ ................................ ............. 68Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page iv 

## List of Tables

Table Page

1 Notices to Lessees and Operators (NTLs) that are referenced in this Environmental Impact Analysis (EIA)

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

2 Matrix of impact

- producing factors and affected environmental resources

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

3 Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 3 will contact a certain parish, county, or coastline within 120 days (From: BOEMRE, 2011 Appendix C)

................................ ................................ ..................... 13

4 Ben thic community data from stations near the lease area and in greater water
d epths and more distant stations in more similar depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (From: Wei, 2006; Rowe and Ke nnicutt, 2009)

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

5 Federally

- listed endangered and threatened species in the lease area and along
the northern Gulf Coast

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

6 Transient fish species that may be present in Sigsbee Escarp ment Blocks 39 and 40 (From: National Marine Fisheries Service, 2009)

................................ ........................... 53

7 W ildlife refuges, wilderness areas, and state and national parks within the geographic range of the potential shoreline contacts after 120 days (Fr om: BOEMRE, 2011)

................................ ................................ ................................ ........ 59



## List of Figures

Figure Page

1 Vicinity map for the lease area

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

2 Bathymetric map of the lease area showing the proposed well surface location

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

3 Location of selected environmental features in relation to the lease area

........................ 43Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page v 

## Acronyms and Abbreviations

ADIOS Automated Data Inquiry for Oil Spills

BHL bottom hole location

BLPD barrels of liquid per day

BOEMRE Bureau of Ocean Energy Managem ent, Regulation and Enforcement

BOP blowout preventer

BO PD barrels of oil per day

B.P. before present

BPD barrels per day

CH 4 methane

CO carbon monoxide

CGA Clean Gulf Associates

DD Destin Dome

DP dynamically positioned (drillship)

EA Environmental Assessment

EP Exploration Plan

EDRC estimated daily recovery ca pacity

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ESA Endangered Species Act

EW Ewing Bank

FAD fish

- attracting device

GB Garden Banks

GPS global positioning system

GMFMC Gulf of Mexico Fishery Management
Council

HAPC Habitat Area of Particular Concern

HFRS Helix Fast Response System

HOSS high

- volume open sea skimmer

HWCG Helix Well Containment Group

IPF impact

- producing factor

MARPOL International Convention for the

Prevention of Pollution from Ships

MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MMSCFD million standard cubic feet per day MP Main Pass

MWCC Marine Well Containment Company
NAAQS National Ambient Air Quality Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric
Administration

NO x nitrogen oxides

NPDES National Pollutant Discharge Elimination System

NPS National Park Service

NRC National Research Council

NRCC National Response Corporatio n
NTL Notice to Lessees

NWR National Wildlife Refuge

OCS Outer Continental Shelf

OSAT Operational Scientific Advisory Team

OSRA Oil Spill Risk Analysis

OSRB Oil Spill Response Barge

OSRP Oil Spill Response Plan

OSRV Oil Spill Response Vessel

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

SBF synthetic

- based fluid

SBM synthetic

- based mud

SE Sigsbee Escarpment

SHL surface hole location

SMT spill management team

SO x sulfur oxides

SOSS Supplemental Offshore Skimming System

SWSS Sperm Whale Seismic Study

USCG U.S. Coast Guard

USEPA U.S. Environmental Protection Agency

USFWS U.S. Fish and Wildlife Service

VOC volatile organic compound

VOO Vessel of Opportunity

WCD worst case discharge

WCEP Whooping Crane Easte rn PartnershipSigsbee Escarpment Block s 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 1 

## Introduction

Anadarko Petroleum Corporation (Anadarko) is submitting an Initial Exploration Plan (EP) for Sigsbee Escarpment Blocks 39 and 40 (SE 39, SE 40)

. Eight wells will be drilled; four prospects in SE 39 and four prospects in SB 40

. All wells have their surface hole locations (SHL) and bottom hole locations (BHL) in the same block and are tentatively scheduled to be drilled between the
second half of 2011 and the first half of 2012. This Environmental Impact Analysis (EIA) provide s an analysis of environmental impacts based on the SHLs of these eight wellsite s.

The lease area is 223 miles (359 km) south of the nearest shoreline, 243 miles (392 km) from the onshore support base at Port Fourchon, Louisiana, and 262 miles (422 km) fro m the helicopter base at Houma, Louisiana ( Figure 1 ). Water depths at the wellsites range from 2,541 to 2,612 m (8,336 to 8,569 ft). The drilling rig is yet to be determined but will include the options of a dynamically positioned (DP) drillship, a DP se misubmersible, or a moored semisubmersible.

This EIA was prepared for submittal to the BOEMRE in accordance with applicable regulations, and is a project

- and site

- specific analysis of Anadarko’s planned activities. As specified in

Notice to Lessees and O perators ( NTL ) 2008

- G04, an EIA is a project

- specific analysis that focuses on the impacts of a specific plan to the extent feasible. Potential impacts have been analyzed at a broader level in the Gulf of Mexico deepwater operations and activities

E nviron mental A sses sment (EA) (MMS, 2000), Programmatic Environmental Impact Statements (EISs) for the Outer Continental Shelf Oil and Gas Leasing Programs (MMS, 2007a

, b

, 2008), and
the most re c ent Gulf of Mexico OCS Oil and Gas Lease Sale: 2011 Western Planning Area Lease Sale 218; Draft Supplemental Environmental Impact Statement (BOEMRE, 2011). The analysis from these documents is incorporated here by reference.

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for
evaluat ing oil spill risk during exploratory drilling . According to Holand (1997), the average frequency of a loss of well control incident or “blowout” during exploratory drilling in the

U.S. Gulf of Mexico is 0.00593 blowouts per well drilled, or 1 blowout per 169 exploration wells drilled. Similarly, the MMS (now BOEMRE) Safety and Environmental Management Program blowout incident rate for 1996 to 1999 was approximately 5 blowouts per 1,000 well starts, or 1/200 ( MMS, 2000 ). More recently in its supplemental EIS for the Western Gulf of Mexico Planning Area, BOEMRE confirmed that “significant changes to the spill rates for the entire OCS are not anticipated” (BOEMRE, 2011).

Historically, most blowouts have not resulted in oil spills . O f 151 well blowouts in t he Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills. The to tal volume released from
all these spills was 1,000 bbl of crude oil and condensate ( MMS, 2007a). Between 1964 and 1999, almost all offshore spills (94%) from drilling and p roduction

- related operations on the

U.S. O uter C ontinental S helf (OCS) were less than or equal to 1 bbl in size (Anderson and LaBelle, 2000) . As BOEMRE recognized in its Interim Final Safety Rule, 75 Fed. Reg. 63365 (10 October 2010) following the Macondo blowout and oil spill, “Based on the occurrence of only a single catastrophic blowout, the GOM Deepwater wells drilled historically (4,123) and the forecasted future drilling activity in the GOM (160) wells per year), the baseline risk of a catastrophic b lowout is estimated to be about once every 26 years.”Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 2

Figure 1. Vicinity map for the lease area.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 3 Anadarko submitted an updated Gulf of Mexico Regional Oil Spill Response Plan (OSRP) on
21 July 2011. In addition, Anadarko submitted a Regional OSRP Cert ification Letter per

30 CFR 254.2(b) to BOEMRE on 21 July 2011

. The Certification Letter was accepted by BOEMRE on 27 July 2011. The OSRP provides a detailed plan by which Anadarko will respond to rapidly and effectively manage oil spills that may result from drilling and production operations.
Anadarko has designed its response program based on a regional capability of responding to a range of spill volumes that increase from small operational spills up to a worst case discharge (WCD) from a well blowou t. Anadarko’s program meets the response planning requirements of
the relevant coastal states and applicable F ederal oil spill planning regulations. The OSRP includes information regarding Anadarko’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental sensitivities. The OSRP descri bes personnel and equipment mobilization, the incident management team organization, and an overview of actions and notifications to be taken in the event of a spill.

Th is EIA is organized into Sections A through I corresponding to the information required by

NTL 2008

- G04. The main impact

- related discussions are in Section A (Impact

- Producing Factors)
and Section C (Impact Analysis). Table 1 lists and summarizes the NTL s that are referenced in
this EIA.

Table 1. Notices to Lessees and Operators (NTLs) that are referenced in this Environmental Impact Analysis ( EIA )

.

NTL Title Summary

2010

- N10 Statement of Compliance with Applicable Regulations and
Evaluation of Informati on Demonstrating Adequate Spill Response and Well Containment

Resources Informs operators using subsea blowout preventers (BOPs) or surface BOPs on floating facilities that applications for well permits must include a statement signed by an authorized

comp any official stating that the operator will conduct all activities in compliance with all applicable regulations, including the increased safety measures regulations (75 FR 63346). Informs operators that BOEMRE will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond to a
blowout or other loss of well control.

2010

- N06 Information Requirements for Exploration Plans, Development
and Production Pl ans, and Development Operations
Coordination Documents on the

OCS Rescinds the limitations set forth in NTL 2008

- G04 regarding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in
blowout scenari o and worst case discharge scenario descriptions.

2009

- G40 Deepwater Benthic Communities Guidance for avoiding and protecting high

- density deepwater benthic communities (including chemosynthetic and deepwater coral communities) from damage caused by Outer Continental Shelf (OCS) oil and gas activities in water depths greater than 300 m (984 ft). Prescribes separation distances
of 610 m (2,000 ft) from each mud and cuttings discharge
location and 76 m (250 ft) from all other seafloor
disturbances.

2009

- G3 9 Biologically

- Sensitive Underwater
Features and Areas Guidance for avoiding and protecting biologically sensitive features and areas (i.e., topographic features, pinnacles, low relief live bottom areas, and other potentially sensitive biological features) when conducting OCS operations in water depths less than 300 m (984 ft) in the Gulf of Mexico.Table 1. (Continued).

Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 4 NTL Title Summary

2009

- G06 Military Warning and Water Test

Areas Provides contact links to individual command headquarters for the military warning and water test areas in the G ulf of Mexico. Lease stipulations require lessees or designated
operators to enter into an agreement with the appropriate individual military command headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in the app licable warning area or water test area before commencing such traffic.

2008

- G04 Information Requirements for Exploration Plans and Development Operations
Coordination Documents Guidance on the information requirements for OCS plans, including EIA require ments and information regarding compliance with the provisions of the Endangered Species
Act and Marine Mammal Protection Act.

2007

- G04 Vessel Strike Avoidance and Injured/Dead Protected Species Reporting Recommends protected species identification traini ng, recommends that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species.

2007

- G 03 Marine Trash and Debris
Awareness and Elimination Instructs operators to exercise caution in the handling and disposal of small items and packaging materials; requires the posting of placards at prominent locations on offshore vessels and structures; an d mandates a yearly marine trash and debris awareness training and certification process.

2005

- G07 Archaeological Resource Surveys and Reports Provides guidance on regulations regarding archaeological discoveries, specifies requirements for archaeological resource surveys and reports, and outlines options for protecting archaeological resources.Sigsbee Escarpment Blocks 39 and 40 June 201 1 Environmental Impact Analysis for Initial Exploration Plan Page 5 

## A. Impac t

- Producing Factors

Table 2 is a matrix of impact

- producing factors (IPFs) and potentially affected environmental resources adapted from Form MMS

- 142. An “X” indicates that an IPF could reasonably be expected to affect a certain resource, and a dash (

-- ) indicates no impact or negligible impact. Where there may be an effect, an analysis is provided in Section C

. Potential IPFs for the proposed activit y are listed below and briefly discussed in the following subsections:

• Drilling rig presence (including noise and lights);

• Physical disturbance to the seafloor;

• Air pollutant emissions;

• Effluent discharges;

• Water intake;

• Onshore waste disposal;

• Marine deb ris;

• Support vessel and helicopter traffic; and

• Accidents.



## A.1 Drilling Rig Presence (including noise and lights)

The three types of exploratory drilling rigs available for this project are the following:

1. Dynamically positioned (DP) drillship;

2. DP semisubme rsible; and

3. Anchored semisubmersible.

DP drillships and DP semisubmersibles use a geographic positioning system (GPS) and sensors in conjunction with their own propellers and thrusters to maintain position. Essentially, through satellite navigation, the location of the vessel is precisely monitored, and thrusters positioned at various locations about the vessel’s hull are activated to provide any required stationkeeping adjustment. This allows operations at sea where mooring or anchoring is not feasible

.
An anchored semisubmersible requires the placement of anchors on the seafloor and thus is subject to NTL 2009 G40 requiring anchors to be placed a minimum of 76 m (250 ft) from deepwater b enthic c ommunities

.

The drilling vessel for the well proposed in t his EP will be on site for an estimated 120 days for
each well

. The physical presence of the drilling rig in the ocean can attract pelagic fishes and
other marine life

, as discussed in Section C.5.1

.
Drilling operations produce noise that includes strong tonal components at low frequencies, and
in some cases infrasonic frequencies (MMS, 2000). Drilling noise from drillships and semisubmersibles is not particularly intense and is strongest at low frequencies, averaging

10 to 500 Hz (Richardson et al., 1995 ). From a drilling rig , sound and vibration paths to the water flow either through the air or through the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with applicable Federal safety regulations.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial E xploration P lan Page 6 Table 2. Matrix of impact

- producing factors and affected environmental resources. X = potential impact; dash (

-- ) = no impact or negligible impact.

Environmental Resources Impact

- producing Factors Drilling Rig Presence (incl. noise & light s) Physical Disturbance to Seafloor Air Pollutant
Emissions Effluent Discharges Water Intake Onshore
Waste Disposal Marine Debris Support Vessel/Helo

Traffic Accidents Small Fuel Spill Oil Spill (WCD) Physical/Chemical Environment Air quality a nd greenhouse gases

-- -- X (9)

-- -- -- -- -- X (6) X (6) Water quality

-- -- -- X

-- -- -- -- X (6) X (6) Seafloor Habitats and Biota Soft bottom benthic communities

-- X

-- X

-- -- -- -- -- X (6) High

- density deepwater benthic communities

-- -- (4)

-- - - (4 )

-- -- -- -- -- X (6) Designated topographic features

-- -- (1)

-- -- (1)

-- -- -- -- -- -- Pinnacle trend area live bottoms

-- -- (2)

-- -- (2)

-- -- -- -- -- -- Eastern Gulf live bottoms

-- -- (3)

-- -- (3)

-- -- -- -- -- -- Threatened, Endangered, and Pro tected Species and Critical Habitat Sperm whale (endangered) X (8)

-- -- -- -- -- -- X (8) X (6,8) X (6,8) West Indian manatee (endangered)

-- -- -- -- -- -- -- X (8)

-- X (6,8) Endangered mysticete whale s

-- -- -- -- -- -- -- -- -- -- Non

- endangered marine mammals (protected) X

-- -- -- -- -- -- X X (6) X (6) Sea turtles (endangered/threatened) X (8)

-- -- -- -- -- -- X (8) X (6,8) X (6,8) Piping Plover (threatened)

-- -- -- -- -- -- -- -- -- X (6) Whooping Crane (endangered)

-- -- -- -- -- -- -- -- -- X (6) Gul f sturgeon (threatened)

-- -- -- -- -- -- -- -- -- X (6) Beach mice (endangered)

-- -- -- -- -- -- -- -- -- X (6) Coastal and Marine Birds

Marine birds X

-- -- -- -- -- -- X X (6) X (6) Shorebird s and coastal nesting birds

-- -- -- -- -- -- -- X

-- X (6)
F isheries Resources Pelagic communities and ichthyoplankton X

-- -- X X

-- -- -- X (6) X (6) Essential Fish Habitat X

-- -- X X

-- -- -- X (6) X (6) Archaeological Resources Shipwreck sites

-- -- (7)

-- -- -- -- -- -- -- X (6) Prehistoric archaeological site s

-- -- (7)

-- -- -- -- -- -- -- X (6) Coastal Habitats and Protected Areas

Beaches

-- -- -- -- -- -- -- -- -- X (6) Wetlands and seagrass beds

-- -- -- -- -- -- -- X

-- X (6) Coastal wildlife refuges and wilderness areas

-- -- -- -- -- -- -- -- -- X (6)
S ocioeconomic and Other Resources

Recreational and commercial fishing X

-- -- -- -- -- -- -- X (6) X (6) Public health and safety

-- -- -- -- -- -- -- -- -- X (6) Employment and infrastructure

-- -- -- -- -- -- -- -- -- X (6) Recreation and tourism

-- -- -- -- -- -- -- -- -- X (6) Land use

-- -- -- -- -- -- -- -- -- X (6) Other marine uses

-- -- -- -- -- -- -- -- -- X (6)

WCD = worst case discharge.Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 7 Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary or topographic feature . Specifically, if the well, rig site, or any anchors will be on the seafloor within the following: (a) 4

- mi zone of the Flower Garden Banks, or the 3

- mi zone of Stetson Bank; (b) 1,000

- m, 1

- mi, or 3

- mi zone of any topographic feature (submarine bank) pro tected by the Topographic Features Stipulation attached to an Outer Continental Shelf (OCS) lease; (c) Essential Fish Habitat (EFH) criteria of 500 ft from any no

- activity zone; or (d) Proximity of any submarine bank (500

- ft buffer zone) with relief greate r than 2 m that is not protected by the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or no

- activity
zone. There are no submarine banks in the block s

. (2) Activities with any bottom disturbance within an OCS lease block protected th rough the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.

• The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area.

(3) Activities within any Eastern Gulf OCS block where seafloor habitats are protected by the Live Bottom (Low

- Relief) Stipulation attached to an OCS lease.

• The Live Bottom (Low

- Relief) Stipulation is not applicable to the lease area.

(4) Activities on blocks designated by BOEMRE as being in water depths 300 m or greater.

• No impacts on high

- density deepwater benthic communities are anticipated. There are no features indicative of high

- density chemosynthetic communities or coral communities within 610 m ( 2,000 ft) of

any drilling mud/cuttings discharge location.

(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be encountered.

• Based on CFR 250.417 (c ), Anadarko is requesting that BOEMRE classify the area as “H 2 S absent .”
Anadark o will submit an H 2 S Contingency Plan prepared according to 30 CFR 250.417(f) before conducting the proposed exploration activities.

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you
determi ne would impact these environmental resources. If the proposed action is located a sufficient distance from a resource that no impact would occur, the EIA can note that in a sentence or two.

• Accidental hydrocarbon spills could affect the resources marked (X) in the matrix, and impacts are analyzed in Section C

. (7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by BOEMRE as having high

- probability for the occurrence of shipwrecks or prehistoric sites, including such blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would

occu r, the EIA can note that in a sentence or two.

• No impacts on archaeological resources are expected. T he lease area is not on the list of high

- probability blocks for shipwrecks and is well bey ond the 60

- m depth contour used by BOEMRE as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico.

(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals
or sea turtles or their critical habitats.

• IPFs that may affect marine mamma ls, sea turtles, or their critical habitats include drilling rig presence and emissions, support vessel and helicopter traffic , and accidents. See Section C

. (9) Production activities that involve transportation of produced fluids to shore using shuttle t ankers or barges.

• Not applicable.Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 8 

## A.2 Physical Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP drillships and DP semisubmersibles disturb only a very small area of the seafloor around t he wellbore (SHL) where the bottom tem plate and blowout preventer (BOP) are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac).

Anchoring cause s physical compaction of the seafloor beneath the anchor

, and chains or lines
can disturb the botto m as well as resuspend sediment s as they move about

. A disturbed area
on the sea bottom called the “anchor sweep” forms by the swing arc of anchor lines scraping across bottom within the range allowed by the anchoring system configuration (BOEMRE, 2011).
Anchored semisubmersibles will disturb approximately 2 to 3 ha (5 to 7 ac) of seafloor at each
well site , depending on the number of anchors and their mooring configurations (MMS, 2007b).



## A.3 Air Pollutant Emissions

Air pollutant emissions are estimated t o be insignificant according to EP Section G

. Offshore air pollutant emissions will result from operations of the drilling rig, as well as service vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The combustion of
fu els occurs on diesel

- powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended particulate matter (PM), sulfur oxides (SO
x ), nitrogen oxides (NO
x ), volatile organic com pounds (VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accordance with BOEMRE requirements
demonstrates that the projected emissions are below exemption levels set by the applicable regulations in 30 CFR 250.303 . Based on th is and the distance to shore, it can be concluded that the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required.



## A.4 Effluent Discharges

Efflue nt discharges are summarized in EP Section F

. All offshore discharges will be in
accordance with requirements of the National Pollutant Discharge Elimination System (NPDES)
General Permit No. GMG290000 issued by the U.S. Environmental Protection Agency ( U SEPA )

. Any d ischarges will be in compliance with the permit terms and will be monitored as required by the permit.

Water

- based drilling muds and cuttings will be released at the seafloor during the initial well
intervals before the marine riser is set tha t allows returns to the surface. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. All muds and cuttings associated with synthetic

- based drilling muds (SBMs)
will b e collected on the rig and either reused by the vendor, or transported to Port Fourchon for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

Other effluent discharges in accordance with the NPDES permit will include excess cement,

non

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, unco ntaminated fresh water and sea water, and ballast water.Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 9 

## A.5 Water Intak e

Seawater will be drawn from the ocean for once

- through, non

- contact cooling of machinery on the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water i ntake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organisms. The current general NPDES permit No. GMG 290000 does not specify requirements for existing facilities (t hose that started construction before

16 July 2006)

. The rig planned for use in this EP is not a “new” facility as defined by the NPDES permit and therefore is not subject to the cooling water intake regulations.



## A.6 Onshore Waste Disposal

Wastes generate d during drilling are tabulated in EP Section F

. Approximately 50 bbl of trash will be generated each month of operations, or a total of 200 bbl for each well proposed under this EP. This trash will be transported to shore in disposal bags where it will be picked up by municipal operators for final disposal in accordance with applicable regulations.



## A.7 Marine Debris

Anadarko will comply with all regulations relating to solid wastes handling and disposal, including the International Convention for the Pr evention of Pollution from Ships (MARPOL 73/78) Annex V requirements, the USEPA’s and U.S. Coast Guard’s ( USCG ) regulations, along with those of BOEMRE

. For example, BOEMRE regulations at 30 CFR 250.300(a)
and (b)(6) prohibit operators from deliberately d ischarging containers and other similar materials (i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools and containers (especially drums), and
other material. USCG and USEP A regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, posting informational placards, manifesting trash sent to shore, and using special precautions such as covering outsi de trash bins to prevent accidental loss of solid waste. In addition to its regulations in Part 250, BOEMRE has issued NTL 2007

- G03

, which instructs operators to exercise caution in the handling and disposal of small items and packaging materials, require s the posting of placards at prominent locations on offshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process.



## A.8 Support Vessel and Helicopter Traffic

Anadarko will use existing shorebase facilities at Port Fourchon, Louisiana , for onshore support for vessel activities. Air transportation (helicopters) will come out of facilities in Houma, Louisiana.

N o terminal expansion or construction is planned at either location

.
The project will be supported by one crew boat and one supply vessel. The crew vessel will
make three round

- trip s per week and the supply vessel will make two round

- trips per week. The boats will normally move to the project area via the most direct route from the shorebase

.
A helicopter will make one round

- trip daily between the drilling rig and the heliport

. The helicopter will be used to transport personnel and small supplies and will normally take the
most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m (700 ft)Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 10 while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines, and

610 m (2,000 ft) over populated areas and sens itive habitats such as wildlife refuges and park properties.



## A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

• S mall fuel spill, which is the most likely type of spill during OCS exploration activ ities; and

• WCD for this EP, which is an oil spill resulting from an uncontrolled blowout.

The following subsections summarize assumptions about the size s and fate s of these spills, as
well as Anadarko ’s spill response plans. Impacts are analyzed in Sectio n C

.
The lease sale EIS (MMS, 2007b) analyzes three other types of accidents: chemical spills, vessel collisions, and loss of well control. The information in the lease sale EIS is incorporated here. These accidents are discussed briefly in Section A.9.4

.



### A.9.2 Small Fuel Spill

Spill Size . According to the analysis in MMS (2007b ; BOEMRE, 2011 ), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have been < 1 bbl, a nd this size is predicted to be the most c ommon in ongoing and
future OCS activities in the Western and Central Gulf of Mexico Planning Areas . As spill size increases the incident rate declines dramatically (MMS, 2007b ; BOEMRE, 2011 ). The average
size fo r spills < 1 bbl is 0.07 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl (MMS, 2007b). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

The water

- soluble fractions of diesel are dominated by two

- and three

- ringed polycyclic aromatic hydrocarbons (PAH s ), which are moderately volatile (National Research Council [NRC], 2003). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel is so light that it will not sink to the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high

- suspended solids loads (NRC, 2003) and would not be exp ected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes ( National Oceanic and Atmospheric Administration [ NOAA ] , 2006). . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiv eness of spill response activities. However, g iven the open ocean location of the lease area and response actions, it is expected
that impacts from a small spill would be minimal (BOEMRE, 2011)

.

For purposes of this EIA, t he fate of a small diesel fuel spill was estimated using NOAA’s ADIOS2 (Automated Data Inquiry for Oil Spills) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and dispersion over time, as well as chan ges inSigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 11 the density, viscosity, and water content of the product spilled. I t is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea
surface with diesel fuel on it during this 24

- hour period would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill,
indicate that a small fuel spill would not have any impacts on coas tal or shoreline resources.
The lease area is 223 miles (359 km) south of the nearest shoreline. Modeling results discussed below indicate that a spill in the lease area w ould have a 9% or less probability of reaching the
coastal areas of Louisiana withi n 10 days after a spill. By this time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, without taking into

account Anadarko ’s response measures. MMS (2007b) concluded that spills <1,000 bbl are not

exp ected to persist as a slick on the surface of the water beyond a few days and are unlikely to make landfall or reach coastal waters prior to breaking up. MMS (2007b) noted that this conclusion is supported by a previous analysis of 3

- day trajectory model runs, previous weathering analyses, and historical records of spill incidents.

Spill Response



### A.9.3 Crude Oil Spill (Worst Case Discharge) . In the unlikely event the shipboard prevention procedures fail to prevent a fuel spill, response equipment and trained personnel would be activated so that any spill effects
would be localized and would result only in short

- term environmental consequences.

EP Section 9b provides a detailed discussion of Anadarko ’s response to a spill.

Spill Size

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a blowout during exploration drilling based on U.S. Gu lf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of

0.0017 per exploratory well for non

- North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005 , half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEMRE is in the process of updating these spill frequency estimates to include the recent Macondo event; however, significant changes to the spill rat es for the entire OCS are not anticipated ( BOEMRE, 2011 ). . In accordance with r equirements of NTL 2010

- N06, Anadarko has estimated a WCD
for this EP as 256,561 barrels per day (BPD). The estimated time to drill a relief well is 61 days, and the total volume of a spill over this duration would be 15.65 million barrels of oil ( MMBO ). The detailed analysis of this calculation can be found in EP Section H

.

As noted in the introduction, the baseline risk of a catastrophic blowout is estimated to be once every 26 years (BOEMRE Interim Final Safety Rule 75 Fed. Reg. 63365

– 10 October 2010).

Included in EP Section H i s Anadarko ’s calculations and information as required by

NTL 2010

- N06, which include descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout.

A nadarko will also comply with NTL 2010

- N 10 and the Interim Final Drilling Safety Rule, which specif ies additional safety measures for OCS activities.

Spill Trajectory

. The fate of a large oil spill in the lease area would depend on meteorological
and ocea nographic condition s at the time. The Oil Spill Risk Analysis (OSRA) model is aSigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 12 computer simulation of oil spill transport that uses realistic data for winds and currents to predict spill fate. While this model has received some criticism recently (Earth justice, 2011), it is still the most widely, scientifically accepted model for estimating the fate of small fuel spills.

The primary criticism of the earlier OSRA model results as provided in Ji et al. (2004) was that
the model did not evaluate the fate of a spill over time periods longer than 30 days, nor does it predict the fate of a release that continues over a period of weeks or months, as in the Macondo ( Deepwater Horizon ) incident. Also as noted by Ji et al. (2004), the OSRA model does not take

into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size
bu t has generally been used by BOEMRE to evaluate contact probabilities for spills greater than 1,000 bbl.

To address this criticism a special OSRA run was conducted for the recent BOEMRE Western Gulf
of Mexico Planning Area Supplemental EIS (BOEMRE, 2011) in order to estimate the impacts of a possible future cat astrophic long

- duration oil spill. In this OSRA model run

, a hypothetical high

- volume, long

- duration oil spill was assumed to have occurred, and the analysis emphasized modeling a spill that continued for 90 consecutive days, with each trajectory tracked for up to 120 days.

The OSRA model run for this analysis was conducted for f ive hypothetical launch points in the

C entral and W estern Gulf of Mexico Planning Areas. These launch point locations were deliberately placed in area s identified as having a hig h possibility of finding the largest oil volumes in each region.

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf are a west of the Mississippi River

— lat. 28.98660 N, long. 92.17851 W;

2. Central Gulf of Mexico shelf area east of the Mississippi River

— lat. 29.91388 N, long. 88.15338 W;

3. Central Gulf of Mexico slope area

— lat. 27.31998 N, long. 90.22203 W;

4. Western Gulf of Mexico shelf area

— lat. 27.55423 N, long. 96.76627 W; and

5. We stern Gulf of Mexico slope area

— lat. 27.51367 N, long. 94.5 1836 W.

The results for Launch Point 3, are the most applicable to this project area and within the Central Planning Area are presented in Table 3

.
OSRA is a preliminary risk assessment model. In the event of an actual oil spill, realtime monitoring and trajectory modeling would be conducted using current and wind data available from the rigs and permanent production structures in the area. Satellite and aerial monitoring of the plume and realtime trajectory modeling using wind and current data would co ntinue on a daily basis to help position equipment and human resources throughout the duration of any major spill or uncontrolled release.Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 13 Table 3. Conditional probabilities expressed as percent chance that an oil spill starting at
Launch Point 3 w ill c ontact a c ertain p arish, c ounty, or c oastline within 120 d ays (From: BOEMRE, 2011 Appendix C).

Season Winter Spring Summer Fall

Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120 County or Parish Percent Chance

Cameron, Texas

-- -- -- 2

-- -- -- -- -- -- -- 2

-- -- -- 2 Willacy, Texas

-- -- -- 3

-- -- -- -- -- -- -- 2

-- -- -- 3 Kenedy, Texas

-- -- -- 8

-- -- -- 1

-- -- -- 9

-- -- -- 5 Kleberg, Texas

-- -- 1 6

-- -- -- -- -- -- -- 4

-- -- 1 6
Nueces, Texas

-- -- 1 6

-- -- -- -- -- -- -- 2

-- -- 1 2
Aransas, Texas

-- -- -- 5

-- -- -- 1

-- -- -- 3

-- -- -- 2 Calhoun, Texas

-- -- 1 6

-- -- -- -- -- -- -- 6

-- -- 1 4 Matagorda, Texas

-- -- 2 17

-- -- 3 4

-- -- -- 11

-- -- 1 6 Brazoria, Texas

-- -- 3 12

-- -- 1 3

-- -- 2 8

-- -- 1 5 Galveston, Texas

-- -- 3 10

-- -- 3 6

-- -- 2 5

-- -- 1 4 Jefferson, Texas

-- -- 1 4

-- -- 7 9

-- -- 1 1

-- -- -- 2 Cameron, Louisiana

-- -- 1 4

-- -- 11 12

-- 1 1 4

-- -- -- 4 Vermilion, Louisiana

-- -- 1 2

-- -- 5 6

-- 1 1 2

-- -- -- -- Iberia, Louisiana

-- -- -- 1

- - -- 4 4

-- -- -- -- -- -- -- -- Terrebonne, Louisiana

-- 1 2 3

-- 4 12 14

-- -- -- 2

-- -- -- -- Lafourche, Louisiana

-- -- 1 1

-- 2 8 10

-- -- 1 2

-- -- -- -- Jefferson, Louisiana

-- -- -- 1

-- -- 2 2

-- -- 1 1

-- -- -- -- Plaquemines, Louisiana

-- - - -- 1

-- 2 10 12

-- -- 1 2

-- -- -- -- Jackson, Mississippi

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Baldwin, Alabama

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Bay, Florida

-- -- -- -- -- -- -- 1

-- -- -- -- -- -- -- -- Franklin, Florida

-- - - -- 1

-- -- -- -- -- -- -- -- -- -- -- -- Monroe, Florida

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- 1 Dade, Florida

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- -- Coastline

Texas

-- -- 12 78

-- -- 14 24

-- -- 6 54

-- -- 4 41

Louisiana

-- 1 6 14

-- 9 52 60

-- 1 4 13

-- -- -- 6 Mississippi

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Alabama

-- -- -- -- -- -- 1 1

-- -- -- -- -- -- -- -- Florida

-- -- -- 1

-- -- 1 4

-- -- -- 2

-- -- -- 2 Tamaulipas, Mexico

-- -- -- 4

-- -- -- 1

-- -- -- 10

-- -- -- 10

Veracruz

- Llave, Mexico

-- -- -- -- -- -- -- -- -- -- 1 7

-- -- -- 1 Tabasco, Mexico

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- --

“

- - ” = V alues <0.5% ; any areas where percent chance within 120 days of all season s are all <0.5% are not shown.

Wea thering . Following an oil spill, several physical, chemical, and biological processes, collectively called weathering, interact to change the physical and chemical properties of the oil, influencing potential effects to marine organisms and ecosystems. T he most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water

- in

- oil emulsions, photochemical oxidation, microbial degradation, adsorption to suspended particulate matter, and stran ding on shore or sedimentation to the seafloor (NRC, 2003).Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 14 Weathering decreases the concentration of oil and produces changes in its chemical composition, physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are lo st rapidly by evaporation and dissolution from a slick on the water surface. Evaporated hydrocarbons are degraded rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n

- alkanes and t hen the light aromatics from the oil. Other petroleum components are biodegraded more slowly.
Photo

- oxidation attacks mainly the medium and high molecular weight PAHs in the oil on the
water surface.

Spill Response

NTL 2010

- N10

— Statement of Compliance wit h Applicable Regulations and Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources : . BOEMRE has issued re c ent NTL’s and g uidance documents that clarify additional
oil

- spill requirements after the Macondo spill occurred ( BOEMRE, 2011 ). These spill

- response

- related NTL’s are listed in Table 2 and the guidance documents are as follows:

This NTL, effective November 8, 2010, applies only to operators conducting operations using subsea or surface BOP’s on floating fac ilities. It explains that lessees and operators submit a statement signed by an authorized company official with each application for a well permit indicating that they will conduct all of their authorized activities in compliance with all applicable regu lations, including the Increased Safety Measures Regulations at 75 FR 63346. The NTL also informs lessees that BOEMRE will be evaluating whether or not each operator has submitted adequate information demonstrating that it has access to and can deploy

sur face and subsea containment resources that would be adequate to promptly respond to a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current OS RP; therefore, there is an incentive for voluntary compliance

.

NTL 2010

- N06

— Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations Coordination Documents on the OCS:
This NTL, effective June 18, 2010, e xplains the procedures for the lessee or operator to submit supplemental information for new or previously submitted EP’s, DPP’s, or DOCD’s. The required supplemental information includes the following: (1) a description of the blowout scenario as require d by 30 CFR 250.213(g) and 250.243(h); (2) a description of their assumptions and calculations used in determining the volume of the worst

- case discharge required by 30 CFR 250.219(a)(2)(iv) (for EP’s) or 30 CFR 250.250(a)(2)(iv) (for DPP’s and DOCD’s); an d (3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early intervention in the event of a blowout, including the arrangements for drilling reli ef wells and any other measures proposed. The early intervention methods of the third requirement could actually include the surface and subsea containment resources that BOEMRE
announced in NTL 2010

- N10, which states that BOEMRE will begin reviewing to e nsure that the measures are adequate to promptly respond to a blowout or other loss of well control.

Anadarko submitted an updated Gulf of Mexico Regional Oil Spill Response Plan (OSRP) on 9 June 2011. In addition, Anadarko submitted a Regional OSRP Certi fication Letter per

30 CFR 254.2(b) to BOEMRE on 15 June 2011. This plan contains detailed information on “Quick Response” procedures including:Sigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 15 • Responsibilities of all Anadarko and contract personnel to report any observed discharge
from known or unknown sources;

• Procedures to locate and determine the size of a discharge; and

• Contact information for alerting the spill management team (SMT) complete with names, phone numbers, and contact points.

In the event of a worst case discharge spill, Anadarko has a ccess to surface and subsea response/containment capabilities that could be implemented through various organizations
under contract. Anadarko's primary spill response equipment provider is Clean Gulf Associates (CGA).

CGA has four skimming vessels capab le of operating in shallow waters and the offshore/nearshore areas. These vessels have o leophilic brush pack skimming systems operating in troug hs built into the hulls; below deck storage ; and marine electronics packages including marine, aircraft and com pany frequency radios, radar, moving map plotters ( global positioning system [ GPS ] ), satellite phone , and depth finders. CGA also offers nine

Fast Response Systems staged throughout the Gulf of Mexico available for offshore use.

The CGA high

- volume open sea skimmer ( HOSS ) barge consists of a skimming system built into an oil recovery barge. There are four 1,000

- barrel recovered oil storage tanks built into the hull where oil can be separated and offloaded. Skimming operations are conducted from the cont rol room overlooking the skimmer deck. The estimated daily recovery capacity (EDRC) for the

HOS S barge is approximately 43,000 barrels.

CGA is currently adding to its equipment stockpile, and has rec ently acquired 11 sets of Koseq skimming arms and two Aq ua Guard skimmers. In addition, an x

- band radar/infrared tracking system is installed on the HOSS barge.

Anadarko has a contract with National Response Corporation (NRCC) for additional spill response equipment. NR C C has a dedicated fleet for the Gulf of Mexico, and has additional available equipment staged throughout the United States. Oil Spill Response Vessels (OSRV)
include the Admiral, Energy

, and Liberty

. Their Oil Spill Response Barges (OSRB s ), Defender and
Valiant

, are equipped with spill contai nment and recovery gear to respond on request.

NRCC's Supplemental Offshore Skimming Systems (SOSS s ) are stored on trailers as units consisting of skimmers, boom, and hydraulic power sources in various locations. Units can be mobilized to a staging area a nd loaded onto a supplemental offshore vessel. Vessels of Opportunity (VOO) will be needed for deployment.

In addition, Anadarko is a member of the Marine Well Containment Company (MWCC) and in the event of an incident, MWCC can provide a 15 ,000

- psi singl e ram capping stack and
d ispersant injection capability for installatio n on a damaged well. MWCC can also install and operate the interim containment system, including subsea flowlines, manifold

, and risers. The interim system is engineered to be used in depths up to 3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day ( BLPD ) (and 120 million standard cubic feet per day [ MMSCFD ] of gas) with potential for expansion. See EP Section H f or a detailed description of
Anadarko ’s site

- specific response to the w orst case spill for this plan.

Anadarko also is a member of the Helix Well Containment Group (HWCG), part of the Helix Fast Response System (HFRS) group , and has available the comm on equipment and services of thatSigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 16 group. Th is agreement allows access to subsea well containment and well shut

- in equipment including the Q4000 and Helix Producer I vessels to facilitate control and containment of spills. At full capacity, the Helix HFRS vessels can handle approximately 55,000 BOP D or 70,000 BLPD

, and 95 MMSCFD at 10,000 psi in water depths to 2,438 m (8,000 ft). HWCG can also provide 10,000

- or 15,000

- psi dual ram capping stack s in addition to those available through MWCC.



### A.9.4 Other Accidents Not Analyzed in Detail

The lease sa le EIS (MMS, 2007b) discusses three other types of accidents: chemical spills, vessel collisions, and loss of well control. The information from the EIS on these topics remains valid and is incorporated by reference into this document. These accidents ar e discussed briefly below along with a hydrogen sulfide ( H 2 S ) release . T here are no other site

- specific issues raised by well drilling proposed in this EP.

Chemical Spills

. Chemicals are stored and used to condition drill muds and during production
and i n well completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the largest volumes spilled. Completion fluids compose the largest quantity of
fluids used and therefore are the largest releases. Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater operations where gas hydrat es tend to form. Spill volumes are anticipated to remain about the same, but spill frequency can be expected to improve because of adv ances in subsea processing (BOEMRE, 2011 )

.
Synthetic

- based Fluid Spills

. Synthetic

- based fluids (SBF’s) have been used s ince the mid 1990’s. In deepwater drilling, synthetic

- based muds (SBM’s) may be preferred over petroleum oil

- based muds because of SBM’s superior performance properties. The synthetic oils used in SBM’s are relatively nontoxic to the marine environment a nd have the potential to biodegrade. Three SBF spills of >1,000 bbl occurred between 2001 and 2004. Between 5 and 20 SBF releases are anticipated each year, with the majority being <50 bbl in size. The volume of the synthetic portion of the drill fluid rather than the total volume of the drill fluid is now used to describe spill size. Accidental riser disconnects could result in the release of large quantities of drilling fluids and are of particular concern w hen SBF’s are in use (BOEMRE, 2011).

Vessel Collisions

. BOEMRE data show that from 1996 to 2009 there were 226 OCS

- related
collisions. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline risers. Approximately 10 % of vessel collision s with platforms in the OCS caused diesel spills. Fires resulted from hydrocarbon releases in several of the collision
incidents. To date, the largest diesel spill associated with a collision occurred in 1979 when an
anchor

- handling boat collided with a drilling platform in the Main Pass leasing area, spilling 1,500 bbl. Diesel fuel is the product most frequently spilled while oil, natural gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of a vessel collision. Human error accounts for approximately half of all reported vessel collisions from 2006 to 2009. As summarized in MMS ( 2007b ) and BOEMRE (2011) environmental impact statements, vessel collisions occasionally occur during routine operations. Some of the se collisions have caused spills of diesel fuel or chemicals. Anadarko will comply with all USCG and BOEMRE

- mandated safety requirements to minimize the potential for vessel collisions.

Loss of Well Control . A loss of well control is the uncontrolled flo w of a reservoir fluid that may result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, whileSigsbee Escarpment Blocks 39 and 40 June 2011
Enviro nmental Impact Analysis for Initial Exploration Plan Page 17 blowouts are considered to b e a subset of more serious incidents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling
fluid or loss of oil. Anadarko has a robust system in place to prevent loss of well con trol.

M easures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout are described in EP Section H as required by

NTL 2010

- 06

. The potential for a loss

- of

- well

- control event will be minimized by adhering to the requirements of applicable regulations such as the Interim Final Drilling Safety Rule and

NTL 2010

- N10 , which specify additional safety measures for OCS activities.

H 2 S Release . Pursuant to 30 CFR 250.490(c), Anadarko requ ests that the Regional Supervisor, Field Operations, classify the area in the proposed drilling operations as an area where H 2 S is absent. This request is also included in the EP. Based on this, no further discussion of H 2 S is
warranted.



## B. Affected En vironment

The lease area is in the central Gulf of Mexico, 223 miles (359 km) south of the nearest shoreline, and 243 miles (392 km) from the onshore support base at Port Fourchon, Louisiana ( Figure 1 ). Based on the geohazards assessment by AOA Geophysics Inc. (2008), w ater depths at the wellsites ( Figure 2 ) i n the lease area range from 2,541 to 2,612 m (8,336 to 8,569 ft) . There is no evidence of significant seafloor or subsurface faulting, fluid expulsion features, or high

- density deepwater benthic comm unities near the wellsites ( AOA Geophysics Inc., 2008)

.
A detailed description of the regional affected environment i s provided in EISs prepared in

2007 and 2008 (MMS, 2007b, 2008), including meteorology, oceanography, geology, air and water quality, benth ic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses. These regional descriptions remain valid and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource are presented in Section C , including site

- specific and/or new information if available.

The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the
oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants we re applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a, b, c). Despite more limit ed information on the water quality of deep water, it is
clear that the condition of the offshore waters of the Gulf of Mexico was altered by the Macondo event. Various monitoring efforts and environmental studies are in progress, but it is currently impo ssible to estimate precisely the long

- term impacts that this spill will have on offshore water quality ( BOEMRE, 2011 ).

The lease area is located approximately 293 miles (471 km) southwest of the Macondo spill site. Based on an analysis of satellite imager y (ESRI, 2010), the surface slic k did not extend over the lease area. In light of the current information available, there is no indication that water quality
in the lease area was affected

. P rior to the Macondo incident, water quality in deep, offshore

waters of the Gulf of Mexico wa s expected to be good

, with low levels of contaminants (Kennicutt, 2000)

. Based on the information currently available, there is no reason to expect any change in water quality conditions in the areas of lease SE 39 and SE 4 0 from those predicted in the multi

- lease

- s ale EISs (MMS 2007b, 2008; BOEMRE, 2011)

.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 18

F igure 2. Bathymetric map of the lease area showing the proposed well surface location. (Water depth in meters.)Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 19 

## C. Impact Analysis

This section analy z es the potenti al direct and indirect impacts of routine activities and accidents. Impacts have been analyzed extensively in the multi

- lease

- sale EISs for the Western and Central
Gulf of Mexico Planning Areas (MMS, 2007b, 2008) as well as the environmental assessment fo r Gulf of Mexico deepwater operations and activities (MMS, 2000). The information in these documents is incorporated by reference. Potential s ite

- specific issues are addressed in this

section.



## C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site

- specific air quality data for the project area due to the distance from shore

. Because of the distance from shore

- based pollution sources and the lack of sources offshore

, air quality at the wellsites is expected to be good. The attainment statu s of Federal OCS waters is unclassified because there is no provision in the Clean Air Act for classification of areas outside

State waters (MMS, 2007b)

.

As of May 2011, all Louisiana, Mississippi, Alabama, and Florida coastal counties and parishes

are in attainment of the National Ambient Air Quality Standards (NAAQS) for all criteria pollutants (USEPA, 201 1 ). Two metropolitan areas in Texas are n onattainment areas for

8

- h ozone (Dallas

- Fort Worth, and Houston

- Brazoria), and El Paso County is a nonattainm ent area for PM 10 (USEPA, 201 1 ).

Winds in the region are driven by the clockwise circulation around the Bermuda High (MMS, 2007b). The Gulf of Mexico is located to the southwest of this center of circulation, resulting in a prevailing southeasterly to sou therly flow, which is conducive to transporting emissions toward shore. However, circulation is also affected by tropical cyclones (hurricanes) during summer and fall, and by extratropical cyclones (cold fronts) during winter.

As noted earlier, based on c alculations made pursuant to applicable regulations, emissions from drilling activities are not expected to be significant as they are below exemption levels. Therefore, the only potential effects to air quality would be from a small fuel spill and a larg e oil spill (WCD).

BOEMRE has re

- examined the analysis for air quality presented in MMS 2007b and 2008 based

on additional information and in consideration of the Macondo oil spill event

. No substantial
new information was found that would alter the poten tial impact s on air quality presented in previous multi

- lease

- sale EIS s (BOEMRE, 2011).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant
emissions will result from the drilling rig operations and helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel

- powered generators, pumps, or motors and from lighter fuel motors.

P rimary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO
x , VOCs,
and CO. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x ,Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 20 NO
x , VOCs, and CO. Emissions of pollutants into the atmosphere from these activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. As
BOEMRE found in the multi

- lease

- sale EISs, the incremental contribution of activities similar to Anadarko’s proposed activities to the cumulative impacts is not significant and will not cause or contribute to a violation of any national ambient air quality standard (MMS, 2007b, 2008). Since

BOEMR E completed the multi

- lease

- sale EISs, USEPA has adopted a new short

- term NAAQS for nitrogen dioxide. The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore , emissions
from Anadarko’s proposed initial EP are not likely to contribute to violations of any NAAQS
onshore.

Carbon dioxide (CO 2 ) and methane (CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activities. According to the Programmatic EIS (MMS, 2007a), estimated CO 2 emissions from all OCS activities in the

2007

- 2012 leasing program are about 0.08% to 0.016% of the global CO 2 emissions from fossil fuel combustion. Greenhouse gas e missions may contribute to climate change, with important effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this proposed project represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the lease sale EIS (MMS

, 2 007b) or Programmatic EIS (MMS, 2007a).

Due to the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MM S, 2007b)

, emissions of air pollutants from routine activities in the Central
Gulf of Mexico Planning Area are projected to have minimal impacts to onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the
distance of these emissions from the coastline

. The Air Quality Emissions Report (see

EP Section G ) prepared in accordance with BOEMRE requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303

, the emissions will not significantly affect the air quality of the onshore area for a ny of the criteria pollutants.

The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Preventio n of Significant Deterioration (PSD) Class I air quality area. BOEMRE is required to notify the National Park Service (NPS) and U.S. Fish and Wildlife Service ( USFWS ) if emissions from proposed projects may affect the Breton Class I area.
Additional revi ew and mitigation measures may be required for sources within 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 296 mi (476 km) from the Breton
Wilderness Area. Because of this distance, impacts on the Breton Wilderness Area are not expected.



### Impacts of a Small Fuel Spill

Potential impacts o f a small spill on air quality are expected to be consistent with th os e analyzed
and discussed in EISs prep ared for lease sales in 2007 and 2008 (MMS, 2007b, 2008). The probability of a small spill would be minimized by Anadarko ’s preventative measures duringSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 21 routine operations, including fuel transfer. In the unlikely event of a spill, implementation of
Anad arko ’s OSRP will reduce the potential impacts. EP Section H includes a detailed discussion
of the spill response measures that would be employed

. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model ( see Section A.9.2 ) indicates that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather
conditions.

A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on air quality are expected to be consistent with th os e analyzed and discussed in the lease sale E ISs (MMS, 2007b, 2008 ; BOEMRE, 2011 ).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts would depend on the meteorological and oceanographic conditio ns at the time and the effectiveness of spill response

measures. Realtime wind and current data from the project area would be available at the time of a spill and would be used to assess the fate and effects of VOCs released. Additional air quality impa cts could occur if response measures included in situ burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of NO x , SO
x , CO, and PM, as well as greenhouse gases

. In situ burning would occur only after authoriz ation from

USEPA.

Due to the lease area location (223 miles [359 km]) from the nearest shoreline), most air quality impacts would occur in offshore waters with minimal chance to affect onshore air quality.



### C.1.2 Water Quality

There are no site

- specific wat er quality data for the lease area. Due to the lease location in deep, offshore waters, water quality is expected to be good, with low levels of contaminants. As noted in the lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occur rences of natural seepage of oil, gas, and brines in near

- surface sediments and up through the water column.

The lease area is located approximately 293 mi (471 km) f r om the Macondo spill site

. Based the general circulation pattern seen in the Gulf of Mex ico and on satellite imagery (ESRI, 2010), the
surface slick from that discharge did not extend over the lease area during the spill . The existing water quality in the lease area is not expected to have been affected by that release.

IPFs potentially affe cting water quality are effluent discharges and two types of accidents:

a small fuel spill and a large oil spill (WCD).Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 22 

### Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and several
kilometers do wn c urrent from the discharge point of drilling muds and cuttings

. Water

- based drilling muds and cuttings will be released at the seafloor during the initial well intervals before
the marine riser is set that allows returns to the surface. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. All muds and cuttings associated with SBMs will be collected on the rig and either reused by the vendor, or transported to Port F ourchon for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit. There will be no persistent impacts on water quality in the lease area (NRC, 1983; Neff, 1987 ; Neff et al., 2000 ).

Treated sanitary and domestic wastes may have a slight transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements will be

met , therefore, l ittle or no impact on wat er quality is anticipated.

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling rig will flow o verboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements.
Based on adherence to permit limits and applicable regulations, l ittle or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, firewater, and ballast w ater are expected to be diluted rapidly

, resulting in little or no impact on water quality.

Support vessels will discharge treated sanitary and domestic wastes. These will have a slight effect on water quality in the immediate vicinity of the discharges. All support vessel discharges will be in accordance with USCG regulations and, as applicable, the NPDES Vessel General Permit, and therefore are not expected to cause significant impacts on water quality.



### Impacts of a Small Fuel Spill

Potential impacts o f a small spill on wate r quality are expected to be consistent with th os e analyzed and discussed in recent EISs (MMS, 2007b, 2008). The probability of a small spill would be minimized by Anadarko ’s preventative measures during routine operations

, includin g fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP will help mitigate
and reduce the impacts

. EP Section H provides detail on spill response measures in addition to the summary information provided in this EIA

. Given th e open ocean location of the lease area, the extent and duration of water quality impacts from a small spill would not be significant.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petro leum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, i t is estimated that over

90% o f a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2 ).Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 23 The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

The water

- soluble fr actions of diesel are dominated by two

- and three

- ringed PAH s , which are moderately volatile (NRC, 2003). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel is s o light that it is not possible for the oil to sink and pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high

- suspended solid loads (NRC, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

A small fuel spill would not affect coastal water quality because the spi ll would not be expected

to make landfall or reach coastal waters due to both response efforts that would be undertaken
as well as natural attenuation (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on wate r q uality are expected to be consistent with th os e analyzed and discussed in the lease sale EISs (MMS, 2007b, 2008). A large spill w ould affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum hydrocarbon s and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at
the surface, although new information from the Macondo spill indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c ; ). How ever, dispersants would be applied only after approval from the USEPA

. Small droplets in the water may adhere

to suspended sediment and be removed from the water column (Operational Scientific Advisory Team (OSAT) 2010).

Due to the lease area location (22 3 miles or 359 km from the nearest shoreline)

, it is expected
that most water quality impacts would occur in offshore waters , especially in the event of a spill lasting less than 30 days

. Based on the revised OSRA modeling ( BOEMRE, 2011 ), there is a 78% c hance that oil from a spill in this lease area would reach shorelines in Texas in winter and a

60 % chance of contacting coastlines in Louisiana in spring within 120 days.



## C.2 Seafloor Habitats and Biota

W ater depths at the proposed SHL range from 2,541 to 2,612 m (8,336 to 8,569 ft) . The seafloor is slightly undulated and featureless at the proposed wellsites and expected to be composed of normal marine clays. No areas of possible hard bottom or mic roseepages were seen within

610 m (2,000 ft) of the wells ites (AOA Geophysics Inc., 2008)

.
Based on the absence of hard bottom areas detected by side

- scan sonar during the hazards survey, the seafloor is expected to consist mainly of soft bottom communities. The geohazards assessment did not identify any featur es that could support high

- density deepwater benthic
communities within 610 m (2,000 ft) of the wellsite. No areas of gaseous sediments or possible hydrocarbon seepage were defined in the study area, and the presence of chemosynthetic

communities is consi dered low ( AOA Geophysics Inc., 2008 ).Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 24 Within the anchor touchdown areas of both wells C and D in Block SE 40 there is a potential high

- density deepwater chemosynthetic community site located 3,468 and 2,438 m (11,380 and 8,000 ft.) to the east and northea st of the SHLs for these two wells. There are also potential high

- density deepwater benthic communities with possible deepwater coral within the 304 m (1,000 ft) anchoring buffer area 3,712 m (12,180 ft) southeast of the W ellsite C and 3,810 m (12,500 ft) northeast of the W ellsite D. These features should b e avoided by at least

76 m (250 ft), and preferably by 152 m (500 ft) as per MMS NTL 2009

- G40, when planning the final configuration of anchors and anchor chain touchdown areas if an anchored
semisubmer sible is selected as the drilling rig for this project (AOA Geophysics Inc., 2010).



### C.2.1 Soft Bottom Benthic Communities

There are no site

- specific benthic community data from the lease area. However, data from the
Northern Gulf of Mexico Continental Slo pe Habitats and Benthic Ecology study (Wei, 2006;

Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area.
The neare st station (B3) is located at 24 miles (39 km) and 22 miles (35 km) from SE 39 and

SE 40

, respectively. Table 4 summarizes data from three nearby stations (B3, NB4, and NB5) located in water depths similar to the lease area (2,020 to 2,600 m [6,627 to 8530 ft]) and two more distant stations (W5 and GFK ) in similar water depths (2,460 to 2,750 m [8,071 to 9,0 22 ft]) to the lease area. Sediments at the closer stations were predominantly clay (47.9% to 57.8%), with 35% to 40.7% silt. The more distant stations at similar water depths were composed of clay (52.7% to 59.9%) and silt (33.6% to 44.5%).

Table 4

. Ben thic community data from stations near the lease area and in greater water depths and more distant stations in more similar depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (From: Wei, 2006 ; Rowe and Ke nnicutt, 2009).

Station Distance to

Lease Area (mi) Water Depth (m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna (individuals/m 2 ) Megafauna (individuals/ha)

B3 22 2,600 155,817 814 362

NB4 31 2,020 148,409 1,443

-- NB5 54 2,065 117,263 706 1,6 00

W5 86 2,750 104,552 659 0

GFK 130 2,460 84,348 737

-- Meiofaunal and megafaunal abundance from Rowe and Kennicutt (2009); macroinfaunal abundance from

Wei (2006).

Meiofauna (animals passing through a 0.5

- mm sieve but retained on a 0.062

- mm sieve)
den sities in water depths representative of the lease area (2,440 to 2,635 m [8,005 to 8,645 ft]) typically range from a pproximately 84,000 to 157,000 individuals/m 2 ( Rowe and Kennicutt, 2009). Nematodes, nauplii

, and harpacticoid copepods were the three dom inant groups in the meiofauna, accounting for about 90% of total abundance.

The benthic macroinfauna is characterized by s mall mean individual size s and low densities

, both of which are a reflection of the meager primary production in Gulf of Mexico surfa ce

waters (Wei, 2006). Densities decrease exponentially with water depth . Based on an equationSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 25 presented by Wei (2006), macroinfaunal densities in the water depths of the lease area are expected to be about to 984 to 1,036 individuals/m 2

, or greater than the numbers in Table 4

.
Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth

- dependent faunal zones (1 th rough 4), two of which are divided horizontally. The lease area is in Zone 3W and at the border of t he southwestern end of

Zone 3E. Zone 3W, with stations in water depths of 1,875 to 3,008 m (6,152 to 9,869 ft)

, had the polychaetes Levinsenia uncinata

, P araonella monilaris

, Tachytrypane sp. A, the bivalve
Heterodonta sp., and the isopod Macrostylis “256” as the most abundant taxa.

Megafaunal densities from nearby stations B3 and NB5 were 362 and 1,600 individuals/ha ( Table 4 ). Common megafauna included m otile groups such as decapods, ophiuroids, holothurians, and demersal fishes, as well as sessile groups such as sponges and anemones.

Bacteria are also an important component in terms of biomass and cycling of organic carbon (Cruz

- Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about

1 to 2 g C m − 2 in the top 15 cm of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout
at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Impacts of Effluent Discharges

Dri lling muds and cuttings are the only effluents that are likely to affect benthic communities. During initial well interval(s) before the marine riser is set, cu ttings and seawater

- based “spud mud” will be released at the seafloor. Excess cement slurry wi ll also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry components typically include cement mix and some of t he same chemicals used in

water

- based drilling muds (Boehm et al., 2001 ). The main impacts will be burial and smothering of benthic organisms within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling muds, and cement slurry will eventually be recolonized through larva l settlement and migration from adjacent areas. Because some deep

- sea biota grow and reproduce slowly, recovery may require several years.

All muds and cuttings associated with synthetic

- based drilling muds (SBMs) will be collected on the rig and either r eused by the vendor, or transported to Port Fourchon for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

Discharges of washed SBM cuttings from the rig ma y affect benthic communities, primarily within several hundred meters of the wellsite. The fate and effects of SBM cuttings have been reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico by Continental Shelf Ass ociates, Inc. (2004, 2006). In general, washed cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic
conditi ons (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may beSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 26 adversely affected due to both the toxicity of the base fluid and organic enrichmen t (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic fluid is decomposed by microbes, the area will gradually return to pre

- drilling conditions. Disturbed sediments will be recolonized through larval settlement and migration from adjacent areas.

T he areal extent of impacts from drilling discharges will be small. As suming a typical effect
radius of 500 m (1,640 ft), the affected area around each wellsite would represent about 3% of
the seafloor within a lease block . Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope ( Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic communities in the region.



### Impacts of a Large Oil Spill (WCD)

The most likely effects of a subsea blowout on benthic communities would be within a few
hundred meters of the wellsite. BOEMRE in its lease sale EIS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius.
While coar se sediments (sands) would probably settle at a rapid rate within 400 m (1,312 ft) from the blowout site, fine sediments (silts and clays) could be resuspended for more than

30 days and dispersed over a much wider area. Based on previous studies, surface sediments at the project area are assumed to largely be silt and clay ( Rowe and Kennicutt, 2009 ).

Previous lease sale EIS documents (MMS, 2007a, 2008) i n dicat ed that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity o f the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010 ; BOEMRE, 2011 ). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). Wh ile the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and per sistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (NRC, 2003).



### C.2.2 High

- Density Deepwater Benthic Communities

As defined by NTL 2009

- G40, high

- density deepwater benthic communities are f eatures or areas that could support high

- density chemosynthetic communities, or features or areas that could support high

- density deepwater corals and other associated high

- density hard botto m communities. Chemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schr oeder, 2007;

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities.Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 27 The nearest known che mosynthetic community site is approximately 109 miles (175 km ) north
of the lease area SE 39, and the nearest identified deepwater coral block is located in SE 40,

54 miles (87 km) to the north

- northeast of the lease area.

The geohazards assessment of the lease area did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling mud/cuttings discharge location. No areas of gaseous sediments or possible hydrocarbon seepage were defined in the study area, and the presence of chemosynthetic communities is
consider ed low. The nearest identified area of seepage potentially supporting high density chemosynthetic communities lies well over 610 m (2,000 ft) to the north of the wellsites.

IPFs potentially affecting high

- density deepwater benthic communities are effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor.

A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface

.


### Impacts of Effluent Di scharges

The shallow hazards study did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling location

, and the presence of chemosynthetic communities in the lease area is co nsidered low. Mo nitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft ) of the wellsite , although detectable deposits may extend beyond thi s distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 2005). Because of the water depth of the lease area, drilling discharges would be expected to result in thinner, more diffuse accumulations on the seafloor than those
documented in t he literature. Although small amounts of cuttings particles may reach areas inhabited by high

- density deepwater benthic communities, the discharges are not expected to
result in significant impacts to these communities.



### Impacts of a Large Oil Spill (WCD)

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact hig h

- density deepwater benthic communities beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajectory, and persistence. Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants , and such approval would be obtained from the USEPA prior to the use of dispersants

.
The biological effects and expected fate of the oil remaining in the Gulf of Mexico from the Deepwater Horizon blowout are still unknown due to the depth and magnitude of this event. Hazen et al. (2010) reported changes in plume hydrocarbon composition with distance from the

source . I ncubation experiments with environmental isolates demonstrated faster than expectedSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 28 hydrocarbon biodegrad ation rates at 5°C. Based on these results, Hazen et al. (2010) suggested the potential exists for intrinsic bioremediation of the oil plume in the deep

- water column without substantial oxygen drawdown.

Potential impacts of oil on high

- density deepwater b enthic communities are discussed by
BOEMRE in its lease sale EIS (2007b). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very constant and occurs at low rates compared to the potential rates of oil release from a blow out. In addition, seep organisms also require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organ isms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; change in sediment characteristics; and reduction or loss of one or more commercial and

rec reational fishery habitats. Sublethal effects could be long

- lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water temperature and diseases).

The potential for a spill to affect deepwater corals is indicated by p reliminary findings from a recent (October 2010) survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010; BOEMRE, 2011). Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead when they visually observed dead and dying corals with sloughing tissue and discoloration. Much of the soft coral observed in an area measuring about 15 to 40 m (50 to 130 ft) was covered by what appeared to be a brow n substance. Ninety percent of 40 large corals were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) away had a colony of stony corals similarly affected and partially covered with a
similar brown substanc e. Until laboratory analyses are conducted, scientists cannot be certain what caused the impacts. Sediment and coral samples were collected with a remotely operated vehicle and brought to the surface for analyses. Further testing will also determine if the substance is oil, and if so, whether it is consistent with the release from the Macondo spill.



### C.2.3 Designated Topographic Features

The block is not within or near a designated topographic feature or a no

- activity zone as
identified in NTL 2009

- G39. The nearest designated topographic feature is located in
Garden Banks (GB) Block 128 approximately 131 miles (210 km) from this project area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to designated to pographic features due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) a nd typically would not carry a plume

up onto the continental shelf edge

.Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 29 

### C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by

NTL 2009

- G39, the nearest pinnacle trend block is Main Pass (MP) 290, which lies 311 miles (501 km) to the northeast of SE 40.

There are no IPFs associated with either routine operations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A s mall fuel spill would float on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these feat ures would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.



### C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low

- Relief) Stipulation, which applies to

Eastern Gulf of Mexico Planning Area leases in water depths of 100 m (328 ft) or less. The
nearest block covered by the live bottom stip ulation, as defined by NTL 2009

- G39, is

Destin Dome (DD) Block 573 approximately 350 miles (563 km) northeast from the lease area.

There are no IPFs associated with either routine operations or accidents that could cause impacts to eastern Gulf live bottom areas due to the distance from the lease area. A small fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor
fea tures. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf

.



## C.3 Threatened, Endangered, and Protected Species and Critical Habitat

This section discusses species listed as endangered or threatened under the Endangered Species Act ( ESA ) . In addition, it includ es all marine mammal species in the region, which are protected
under the Marine Mammal Protection Act ( MMPA )

.
Endangered or threatened species that may occur in the project area and/or along the northern
Gulf C oast are listed in Table 5 . The table also i ndicates the location of critical habitat (if designated in the Gulf of Mexico). Critical habitat is defined as (1) specific areas within the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and (2) specific areas outside the geographical area occupied by the species if the agency determines that the area itself is essential for

conserva tion. The National Marine Fisheries Service ( NMFS ) has jurisdiction for ESA

- listed cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction for

ESA

- listed birds and the West Indian M anatee.Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 30 Table 5

. Federally

- listed endangered and threatened species in the lease ar ea and along the
northern Gulf C oast.

Species Scientific Name Status Potential Presence Critical Habitat Designated in Gulf of Mexico Lease
Area Coastal

Marine Mammals Sperm whale Physeter macrocephalus E X

-- None West Indian manatee Trichechus manatus latirostris E

-- X Florida (Peninsular)
Blue whale Balaenoptera musculus E X a

-- None Fin whale Balaenoptera physalus E X a

-- None Humpback whale Megaptera novaeangliae E X a

-- None North Atlantic right whal e Eubalaena glacialis E X a

-- None Sei whale Balaenoptera borealis E X a

-- None Sea Turtles

Loggerhead turtle Caretta caretta T X X None Green turtle Chelonia mydas T, E b X X None Leatherback turtle Dermochelys coriacea E X X None Hawksbill turtle Er etmochelys imbricata E X X None Kemp’s ridley turtle Lepidochelys kempii E X X None Birds

Piping Plover Charadrius melodus T

-- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E

-- X Coastal Texas (Aransas National Wildlife Refuge)
Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T

-- X Coastal Louisiana, Mississippi, Alabama, and Florida (Panhandle)
Terrestrial Mammals

Beach mice (Alabama, Choctawhatchee, Perdido Key, St. Andrew) Peromyscus p olionotus E

-- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = e ndangered; T = t hreatened.

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to be present in the lease area.

b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.

As mandated by the ESA, BOEMRE consulted with NMFS and USFWS on possibl e and potential impacts from the proposed leasing in the Western Gulf of Mexico Planning Area on endangered/threatened species and their designated critical h abitat (MMS, 2007a,b).

A biological assessment was prepared for each consultation. The formal ES A consultation with NMFS was concluded with receipt of the Biological Opinion on 3 July 2007 (NMFS, 2007 ). The Biological Opinion concludes that the proposed lease sales and as sociated activities in the
Gulf of Mexico in the current 5

- Year Program are not likely to jeopardize the continued existence of threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with a letter dated 14 September 2007. The USFWS concurred with BOEMRE’s determination that proposed actions of the current 5

- Year Program were not likely to adverselySigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 31 affect the threatened/endangered species or designated critical habitat under USFWS jurisdiction. Following the Macondo oil spill BOEMRE requested reinitiation of ESA consultation
with both NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on

24 September 2010. The USFWS responded with a letter to BOEMRE on 27 September 2010.
The reinitiated con sultations are not complete at this time, although BOEMRE is in discussions with both agencies. The existing consultations remain in effect until the reinitiated consultations are completed ( BOEMRE, 2011 ).

Coastal endangered or threatened species include the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of beach mice. Critical habitat has been designated for all of these species as indicated in Table 5 and discussed in individual sections.

Two other coastal species (Bald Eagle and Brown Pelican) discussed by BOEMRE in its lease sale

EIS (2007b) are no longer listed as endangered or threatened . T hese are discussed under
Coastal and Marine Birds.

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No critical habitat has been designated for these species in the Gulf of Mexico.

There are no other endangered animals or plants in the Gulf of Mexico that are reasonably likely
to be affec ted by either routine or accidental events. Other species occurring at certain locations in the Gulf of Mexico such as the smalltooth sawfish ( Pristis pectinata ), elkhorn coral ( Acropora palmata ), staghorn coral ( Acropora cervicornis ), and Florida salt ma rsh vole ( Microtus pennsylvanicus dukecampbelli ) are remote from the lease area and highly unlikely to
be affected.



### C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the sperm whale ( Physet er macrocephalus )

. Resident populations of s perm whales occur within the
Gulf of Mexico. A species description is presented in the lease sale EIS (MMS, 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a “strategic stock” ( defined as a stock that may have unsustainable human

- caused impacts) by NOAA Fisheries (Waring et al., 2009). No critical habitat for the sperm whale has been designated in the Gulf of Mexico.

The distribution of sperm whales in the Gulf of Mexico is corr elated with mesoscale physical features such as eddies associated with the Gulf of Mexico Loop Current (Jochens et al., 2008). Sperm whale populations in the north

- central Gulf of Mexico are present there throughout the

year (Davis et al., 2000). Results of a multi

- year tracking study show female sperm whales typically concentrated along the upper continental slope between the 200

- and 1,000

- m (656

- and 3,280

- ft) depth contours ( Jochens et al., 2008 ). Male sperm whales were more
variable in their movemen ts and were documented in water depths greater than 3,000 m (9,843 ft). Generally, groups of sperm whales sighted in the Gulf of Mexico during the

MMS

- funded Sperm Whale Seismic Study (SWSS) consisted of mixed

- sex groups comprising
adult females and immat ures, and groups of bachelor males. Typical group size for mixed groups was 10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the lease area. Movements of satellite

- tracked individuals suggest tha t this area of the Gulf continental slope is within the home range of the Gulf of Mexico population (within the 95% utilization distribution) (Jochens et al., 2008).Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 32 IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents

– a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the in termittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2007

- G03 will minimize the potential
for marine debris

- related impacts on sperm whales

.

C urrent threats to sperm whale populations worldwide are discussed i n a final recovery plan for the sperm whale recently published by NOAA (NMFS, 2010 a ). Threats are defined as “any factor that could represent an impediment to recovery” and these include fisheries interactions, anthropogenic noise, vessel interactions, co ntaminants and pollutants, disease, injury from marine debris, research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due to climate change and ecosystem change, and cable laying. In
the G ulf of Mexico , the impacts from many of these threats are identified as either low or
unknown ( BOEMRE, 2011 )

.


### Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb sperm whales. Sperm whales appear to have g ood low

- frequency hearing, but the available data do not indicate a consistent response to anthropogenic noise (Jochens et al., 2008). Noise associated with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be trans ient. There
are other OCS facilities and activities near the lease area

, and the region as a whole has a large number of similar sources. Due to the limited scope and short duration of d rilling activities, this project would represent a small temporary c ontribution to the overall noise regime.

The NMFS (2007) analyzed the potential for impacts of drilling

- related noise on sperm whales in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Cen tral and Western
Gulf of Mexico Planning Areas

. The analysis noted that semisubmersible drilling rigs show low sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are in significant (NMFS, 2007).

Drilling rig lighting and rig presence are not identified as IPF s for sperm whales in recent lease sale EISs (MMS, 2007b, 2008) or the NMFS (2007) Biological Opinion.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a ). Data concerning the frequency of vessel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BOEMRE has issued NTL 2007

- G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant
watch for marine mammals and slow down o r stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a
distance of 91 m (300 f t) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel when safety permits. Compliance with thisSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 33 NTL w ill minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm whales.

The NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western
Gulf of Mexico Planning Areas. With implementation of the mitigation measures in

NTL 2007

- G04, NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. The NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or shelt ering to individuals, or have any consequences at the level of the population. With implementation of the vessel strike avoidance measures requirement to
maintain a distance of 90 m (295 ft) from sperm whales, the NMFS concluded that the potential
for har assment of sperm whales would be reduced to discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an
altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during three (12%) of 24 sightings. All three reactions consisted of a hasty dive and occurred at less than

360 m (1,180 ft) lateral distance from the aircraft. Additional react ions were seen when aircraft
circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by
the air craft were short

- term and probably o f no long

- term biological significance.

W hile flying offshore in the Gulf of Mexico , helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animals. Although responses are possible based on the Smultea et al. (2008) study, the NMFS (2007) concluded that t his altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expect ed

.


### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in the lease
sale EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Gulf of Mexico Planning Areas. Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals that were not analyzed in the previous documents

.
The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will mitigate and lessen the potential for impacts on sperm whales. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water su rface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measu res. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturallySigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 34 within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, dep ending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingest ion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft ( Marine Mammal Commission [ MMC ] , 2010). However, due to the limited areal extent and short duration of water quality impacts from a sma ll fuel spill, as well as the mobility of sperm whales, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Gulf of Mexico Planning Areas. For this EP

, there are no unique site

- specific issues with respect to spill impacts on these animals.

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can includ e skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime
habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or
patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

In the event of a large spill, the level of vessel and aircraft a ctivity associated with spill response could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007

- G04 to reduce the potential for striking or dis turbing these animals.



### C.3.2 West Indian Manatee (Endangered)

M ost of the manatee population is located in peninsular Florida (USFWS, 2001). Manatee sightings in Louisiana have been increasing as they extend their presence farther west of Florida
in the w armer months (Wilson, 2003). A species description is presented in the lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil

s pill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees, as the lease

area is approximately 223 miles (359 km) from the nearest shoreline ( Louisiana ). As explained in

Section A.9.2 , a small fuel spill would not be expected t o make landfall or reach coastal waters prior to breaking up

. Compliance with NTL 2007

- G03 will minimize the potential for marine
debris

- related impacts on manatees.Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 35 

### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). To reduce the potential for vessel strikes, BOEMRE has issued NTL 2007

- G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species

, and requires operators to report sightings of any injured or dead prote cted species. Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic also has the potential to disturb manatees. Rathbun (1988) reported that
manatees were disturbe d more by helicopters than by fixed

- wing aircraft; however, the helicopter was flown at a relatively low altitude of 20 to 160 m (66 to 525 ft). Helicopters used in support operations maintain a minimum altitude of 213 m (700 ft) while in transit offshore

, 305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts are expected.



### Impacts of a Large Oil Spill (WCD)

The revised OSRA results ( BOEMRE, 2011 ) summarized in Table 3 predict that during the spring
there is a 9 % chance of an oil spill from this location impacting shorelines along the Lou isiana

coast within 10 days

. There is no critical manatee habitat designated in the areas potentially affected and it is doubtful any manatees would be impacted.

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) direct ly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircr aft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of
social s tructure

, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

In the event that a large spill reached coastal waters where manatees were present , the level of vessel and aircraft activity associated with spill response could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate
in accordance with NTL 2007

- G04 to reduce the potential for striking or disturbing these
animals , and therefore no significant impacts are expected

.



### C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rareSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 36 or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.

Due to the rare occurrence of these whales in the Gulf of Mexico and the limited sco pe and duration of the project, it is highly unlikely that any endangered mysticete would come into contact with any project activities , either routine operations or accidents . The NMFS (2007) did not include any of thes e mysticete whales as affected species in its Biological Opinion for the

Five

- Year Oil and Gas Leasing Program in the Cen tral and Western Gulf of Mexico Planning

Areas . Potential impacts are analyzed in recent lease sale EISs (MMS, 2007b, 2008)

, and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts would be the same as those discussed below in Section C.3.4

.



### C.3.4 Non

- Endangered Marine Mammals (Protected)

Excluding the seven endangered species that have been cited previously, there are 22 additional species of marine mammals that may be found in the Gulf of Mexico. All marine mammals are protected species under the MMPA. This includes two mysticete whales, the dwarf and pygmy sperm whales, 4 species of beaked whales, and 1 4 species of delphinids . The most common

non

- endangered cetaceans in the deepwater environment are odontocetes such as the pantropical spotted dolphin, spinner dolphin, and clymene dolphin. A brief summary is presented belo w, and a dditional information on these groups is presented in the lease sale EIS (MMS, 2007b).

Mysticete whale s . Two non

- endangered mysticete whales are known from the Gulf of Mexico. The Bryde’s whale ( Balaenoptera edeni ) has been sighted most frequentl y along the 100

- m (328

- ft) isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the DeSoto Canyon region and off western Florida, although there have been some in the

west

- central portion of the northeastern Gulf. The m inke whale ( Balaenoptera acutorostrata ) is considered rare in the Gulf of Mexico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it is possible that Bryde’s whales could occur
in the lease area.

Dwarf and pygmy sperm whales

. At sea, it is difficult to differentiate dwarf sperm whales ( Kogia sima ) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as “ Kogia spp.” Both species have a worldwide distribution in tempe rate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mullin et al., 1991). Either species could occur in the
lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked whale ( Ziphius cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon

europaeus ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the most common and Sowerby’s is extralimital. Due to the difficulties of at

- sea identification,
beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked wha les or are grouped into an undifferentiated complex ( Mesoplodon spp. and Ziphius spp.). In the northern Gulf of Mexico, they are broadly distributed in waters greater than 1,000 m (3,281 ft) over lower slope and abyssal landscapes (Davis et al., 2000). A ny of these species could occur in the lease

area.Sigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 37 D elphinids

IPFs potentially affecting non

- endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill represented by the WCD for this EP ). Effluent discharges are likely to have negligible impacts on marine mammals due to rapid di spersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of marine mammals. Compliance with NTL 2007

- G03 will minimize the potential for marine debris

- related impacts on
marine mammals. . Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted dolphin ( Stenella frontalis ), bottlenose dolphin ( Tursiops truncatus ), clymene dolphin ( Stenella cl ymene ), f alse killer whale ( Pseudorca crassidens )

, Fraser’s dolphin ( Lagenodelphis hosei ) , k iller whale ( Orcinus orca ) , m elon

- headed whale ( Peponocephala electra )

, p antropical spotted dolphin ( Stenella attenuata )

, p ygmy killer whale ( Feresa attenuata )

, sho rt

- finned pilot whale ( Globicephala macrorhynchus ) , R isso’s dolphin ( Grampus griseus )

,
r ough

- toothed dolphin ( Steno bredanensis ) , s pinner dolphin ( Stenella longirostris ) , and s triped dolphin ( Stenella coeruleoalba )

. The most common non

- endangered cetacean s in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and clymene dolphin. However, any of these species could occur in the lease area.



### Impacts of Drilling Ri g Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher frequency sounds than the dominant low frequencies produced by OCS drilling activit ies (Richardson et al., 1995). Noise associated with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be
transient. There are other OCS facilities and activities near the lease area

, and the region as a
whole has a large number of similar sources. Due to the limited scope and short duration of drilling activities , this project would represent a small temporary contribution to the overall noise regime

, and any short

- term impacts are not expected to be biologically significant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPF s for marine mammals in lease sale EISs (MMS, 2007b, 2008).



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals

, and there is also a risk of
vessel strikes. Data concerning the frequency of vessel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BOEMRE has issued NTL 2007

- G04,
which reco mmends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any inju red or dead protected species. Vessel operators and crews are required to attempt to maintain a
distance of 91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direction until the cetacean has left the area. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/ca lf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel

, when safety permits. Compliance with this NTL willSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 38 minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine
mammals , and therefore no significant impacts are expected

.

Aircraft traffic also has the potential to disturb marine mammals (W ü rsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing marine mammals

, and no significant impacts are expected ( MMS, 2007b ).



### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008)

, and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For
this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko ’s preve ntative measures during fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP is expected to
lessen the potential for impacts on marine mammals. EP Section H provides detail on spill

response measures , along with a summary of those measures in this EIA

. Given the open ocean location of the lease area, the limited duration of a small spill and response efforts, it is expected that any impacts would be brief and minimal

.
A small fuel spill in offshore waters would produce a sli ck on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of sp ill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha ( 1.2 to 12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of

t oxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel s pill, as well as the mobility of marine mammals, no significant impacts would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in the Outer Continental Oil and Gas Leasing Program EIS for 2007 and 2008 as well as the original deepwater EIS from

2000 (MMS, 2000; 2007b ; and 2008)

. For this EP , there are no unique site

- specific issues

. Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of
social structure

, changing prey availability and fora ging distribution and/or patterns

, changingSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 39 reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response
could disturb m arine mammals and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007

- G04 to reduce the potential for striking or disturbing these animals , and therefore no significant impacts are expected

.



### C.3. 5 Sea Turtles (Endangered/Threatened)

F ive species of endangered or threatened sea turtles may be found near the lease area. Endangered species are the leatherback ( Dermochelys coriacea ), Kemp's ridley ( Lepidochelys kempii ), and hawksbill ( Eretmochelys imbricata ) turtles. The loggerhead turtle ( Caretta caretta ) is a threatened species. The green turtle ( Chelonia mydas ) is listed as threatened, except for the
Florida and Pacific Coast of Mexico breeding population s , which are lis ted as endangered. Species descriptions are presented in the lease sale EIS (MMS, 2007b).

BOEMRE has reexamined the impacts analysis presented in MMS 2007b and 2008 for the five sea turtles species that inhabit the Gulf of Mexico based on additional infor mation and in consideration of the Macondo oil spill event. I nformation from the 5

- year status reviews for federally listed sea turtles in the Gulf of Mexico has been incorporated in the 2011 Draft Supplemental EIS for the Western Gulf of Mexico Planning Area Lease Sale 218 (BOEMRE, 2011). However, no new information from previous EISs was found that would alter the potential impact s on sea turtles. In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oi l slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles.

Leatherbacks and loggerheads are the most likely species to be present near the lease area as adu lts. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and near shore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea turtles may be present in deepwater areas, including the lease ar ea, where they may be
associated with Sargassum and other flotsam.

Sea turtle nesting in the northern Gulf of Mexico can be summarized by species as follows:

• Loggerhead turtles

– Loggerheads nest in significant numbers along the Florida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007 b ) . The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR ;

• Green and leatherback turtles

– Green and leatherback turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2010);

• Kemp’s ridley turtles

– The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas, Mexico (NMFS et al., 2010). Kemp’s ridley turtles typically do not nest

an ywhere near the project area, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles

– Hawksbills typica lly do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill represented by the WCD for this EP ). Effluent discharges are likely to have negligible im pacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent natureSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 40 of the discharges. Compliance with NTL 2007

- G03 will minimize the potential for marine
debris

- related impacts on sea turtles.



### Impacts of Drilling R ig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disruption and temporary or permanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced during routin e operations. Helicopters and service vessels may also affect sea turtles due to machinery noise and/or visual disturbances. The most likely impacts would be short

- term behavioral changes such as diving and evasive swimming, disruption of activities, or departure from the area. Due to the limited scope and short duration of drilling activities , these
short

- term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of s ea turtle hatchlings (Witherington, 1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are insignificant.



### Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles

, and there is also a risk of vessel
strikes. Data show that vessel traffic is one ca use of sea turtle mortality in the Gulf of Mexico (Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in clear weather, they can be difficult to spot from a moving vessel when resting below the water surface, du ring nighttime, or during periods of inclement weather. To reduce the potential for vessel strikes, BOEMRE has issued NTL 2007

- G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch fo r sea turtles and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are sighted, vessel operators and crews are required to attempt to maintain a distance of 45 m (150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Helicopter traffic also has the potential to d isturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are

expe cted.



### Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the
Central and Western Gulf of Mex ico Planning Areas

. For the EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP is expected to

minimize potential impacts on sea turtles. EP Section H provides detail on spill responseSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 41 measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity f or impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally

w ithin 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritati on, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2010). Howeve r, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches, as the
lease area is 223 miles (359 km) from the nearest shoreline (Louisiana). As explained in

Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

.


### Impacts of a Large Oil Spill (WCD)

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and physiological effects can include skin irritation, inflam mation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g., from in situ burning of oil) ; ingestion of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime h abitat

, disruption of social structure

, changing food availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010). In the unlikely event of a spill, implement ation of Anadarko ’s OSRP is expected to minimize the potential for these types of impacts on sea turtles. EP Section H provide s detail on spill

response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) sugge st that sea turtles show no avoidance behavior when they encounter an oil slick

, and any sea turtle in an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface

over time , which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

Spilled oil reaching sea turtle nesting beaches could have e ffects on nesting sea turtles and egg development (NMFS, 2007) . An oiled beach could affect nest site selection or result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that c ontact oilSigsbee Escarpment Blocks 39 and 40 June 2011
Environmental Im pact Analysis for Initial Exploration Plan Page 42 residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired movement and normal bodily functions (NMFS, 2007).

In the event of a large spill, the level of vessel and aircraft activity associated with spill res ponse could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007

- G04 to reduce the potential for striking or disturbing these animals , and therefo re no significant impacts are expected

.



### C.3. 6 Piping Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a res ult of hunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 3 ) . Piping Plovers inhabit coastal s andy beaches and mudflats, feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in
the lease sale EIS (MMS, 2007b).

A l arge oil spill (WCD) is the only IPF potentially affecting Piping Plovers. There are no IPFs associated with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 )

.


### Impacts of a Large Oil Spill (WCD)

Th e lease area is 223 miles (359 km) from the nearest shoreline s inhabited by Pip ing Plovers.
The revised OSRA results (BOEMRE, 2011) summarized in Section A.9.3 ( Table 3 ) predict there is

a 4 % probability (in spring) that an oil spill from this lease area would reach a shoreline designated as critical habitat for the wintering Piping Plover within 10 days. Plovers could physically oil themselves while foraging on oiled shores or secondarily contaminate themselves through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills occur during winter months when plovers are most common along the coastal Gulf or if spills
contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill cleanup. Anadarko has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching th e shoreline, as detailed in the OSRP.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 43

Figure 3. Location of selected environmental features in relation to the lease area. Shown are Essential Fish Habitat (EFH) for coral and coral reefs; Habitat Areas of Particular Concern (HAPCs) for northwestern G ulf of Mexico reefs and banks and spawning Atlantic b luefin tuna; and critical habitat for beach mice, Gulf sturgeon, Piping Plover, and Whooping Crane.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 44 

### C.3. 7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership [WCEP], 2010). One population winters along the Texas coast at Aransas NWR and summers at Wood Buffalo National Park in Canada. This population represents the majority of the world’s population of free

- ranging Whooping Cranes and reached a record population of
270 at Aransas NWR in December 2008 (WCEP, 2010). A non

- migrating population has been

re

- introduced in central Florida, and another re

- in troduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fie lds (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species ( Figure 3 )

. A species description is presented in a recent lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would also be unlikely to affect Whooping Cranes, due to the distance from

Aransas NWR. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. 

### Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whoopin g Cranes as t he lease area is approximately

318 miles (511 km) from its critical habitat (Aransas NWR) and t he revised OSRA modeling (BOEMRE, 2011) predicts a 3% probability (in spring) that an oil spill originating in this lease area would reach the Matag orda Island area of the Aransas NWR in Calhoun County, Texas, within

3 0 days and an 17 % probability (in winter ) of oil reaching that area in 120 days.

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in
oiled ar eas or secondarily contaminate themselves through ingestion of contaminated shellfish, frogs, and fishes . It is possible that some death of Whooping Cranes could occur. In the event of a spill, Anadarko would work with the applicable State and Federal ag encies to prevent impacts from a spill

.



### C.3. 8 Gulf Sturgeon (Threatened)

The Gulf sturgeon ( Acipenser oxyrinchus desotoi ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Flori da (Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water qual ity changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Su lak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) t o Suwannee Sound, F lorida (Levy County) (NMFS, 2010 b ) ( Figure 3 )

. A species description is presented in the lease sale EISSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 45 (MMS, 2007b) and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995)

.
A large oil spill (WCD) is the only I PF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fishes. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be

ex pected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 )

.


### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in the lease sale EISs ( MMS, 2000, 2007b, 2008) and by the NM FS (2007) in its Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Gulf of Mexico Planning Areas. For this EP , there are no unique site

- specific issues with respect to this species.

The lease area is about 302 mil es (486 km) from the nearest Gulf sturgeon critical habitat. The
revised OSRA modeling ( Table 3 ) predicts that a spill in the lease area has 1% or less probability of contacting the coastal areas inhabited by Gulf sturgeon within 30 or 120 days

.

In the ev ent of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. Based on the life history of this species, subadult and adult Gulf stu rgeon would be most vulnerable to an estuarine or marine oil spill, and would be vulnerable only during winter months ( from 1 September through 30 April) when this species is foraging in estuarine and marine habitats (NMFS, 2007).



### C.3. 9 Beach Mice (Endange red)

Four subspecies of endangered beach mice ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawatchee, Perdido Key, and

St. Andrew beach mice. Critical habitat has been designated for all four subspecies ; Figure 3 shows the critical habitat combined for all four subspecies . Species descriptions are provided in

a rece nt lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill in
the lease area would not affect beach mice because a sm all fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2 )

.


### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in the lease sale EISs (MMS, 2007b , 2008).
For this EP , there are no unique site

- specific issues with respect to these species that were not analyzed in these documents

.

The lease area is about 380 miles (612 km) southwest from the nearest beach mouse critical
habitat . The revised OSRA m odeling summarized in Section A.9.3 ( Table 3 ) predicts that a spill
in the lease area has a 1% or less probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 days.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 46 In the event of oil contacting these beaches, b each mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of sweat glands, ear tissues, and throat tissues; disruption of sigh t and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.



## C.4 Coastal and Marine Birds

C.4.1 Marine Birds

Marine birds include seabirds and other species that may occur in the pelagic environment of the project areas (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore over the open ocean, except during breeding sea son when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and
shorebird s may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the dis tance from shore. For a
discussion of shorebird s and coastal nesting birds, see Section C.4.2

.
Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm

- petrels, shear waters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, f our ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (e.g., shearwaters, storm petrels, and boob ies); summer residents that breed in the Gulf (e.g., Sooty Tern, Least Tern, Sandwich Tern, and Magnificent Frigatebird); winter residents (e.g., gannets, gulls, and jaegers); and permanent resident species (e.g., Laughing Gulls, Royal Terns, and Bridled T erns) (Hess and Ribic, 2000).

Common seabird species include Wilson’s S torm

- P etrel ( Oceanites oceanicus ) , Magnificent Frigatebird ( Fregata magnificens ), Northern Gannet ( Morus bassanus ), Masked Booby ( Sula dactylatra ), Brown Booby ( Sula leucogaster ), Cory’ s Shearwater ( Calonectris diomedea ), Greater Shearwater ( Puffinus gravis ), and Audubon Shearwater ( Puffinus lherminieri ). Seabirds
are distributed Gulf

- wide and are not specifically associated with the lease area.

Relationships with hydrographic features were found for several seabird species, possibly due to effects of hydrography on nutrient levels and productivity of surface waters where birds forage. GulfCet II did not estimate bird densities; however, Powers (1987) indicates that seabird
densities ov er the open ocean typically are <10 birds/km 2

.

Trans

- Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and rigs for resting, feeding, or as tempor ary shelter from inclement weather (Russell, 2005). Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate
around these structures.

IPFs potentially affecting marine and pelagic birds include drill ing rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill represented by the WCD for this EP ). Effluent discharges are likely to have negligibleSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 47 impacts on the birds du e to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2007

- G03 will minimize the potential for marine debris

- related impacts on birds.



### Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent rig s may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over
water have been known to strike of fshore structures, resulti ng in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and other land

- based structures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be
simila r. In some cases, migrants simply do not see a part of the rig until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans

- Gulf migrant species, and most of the migrants that stop over on rigs probably benefit from their stay, particularly in spring (Russell, 2005). Due to the limited scope and short duration of drilling activities in this EP, any impacts on populations of either seabirds or trans

- Gulf migrant birds are not expected to be significant.

A recent study in the North Sea indicated that rig lighting causes circling behavior in various birds, especially on cloudy nights; a pparently the birds’ geomagnetic compass is upset by the

r ed part of the spectrum from the lights currently in use (Nederlandse Aardolie Maatschappij, 2007). The numbers varied greatly, from none at all to some tens of thousands of birds per night per rig, with an apparent effe ct radius of up to 3 miles (5 km). A study in the Gulf of Mexico also noted the phenomenon, but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in the Gulf of Mexic o vs. the North Sea. Due to the limited scope and short duration of drilling activities proposed in this EP

, lighting impacts, collisions

, or other adverse effects are unlikely, and no significant impacts are expected.



### Impacts of Support Vessel and Helico pter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore waters. It is likely that individual birds would experience, at most, only short

- term behavioral disruption

, and the impact would not be sig nificant.



### Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in recent EISs (MMS, 2007b, 2008)

. F or this

EP , there are no unique site

- specific issues with respect to spill impacts on these animals.

The probability of a fue l spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will reduce the potential for impacts on marine and pelagic birds.

EP Sec tion H provides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill respon se measures. Section A.9.2 discusses the likely fateSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 48 of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of
toxic fu mes. Due to the limited areal extent and short duration of water quality impacts from a small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the low densities of birds in o pen ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine and pelagic birds are discussed in recent EISs (MMS, 2007b, 2008). For this EP , there are no unique site

- specific issues with respect to spill impacts on these
animals.

BOEMRE has reexamined the analysis for coastal and marine birds presented in MMS 2007b and
2008 and determined that no new info rmation from previous EISs was found that would alter
the potential impact s on marine and pelagic birds (BOEMRE, 2011).

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported that terns, storm

- petrels, sh earwaters, and jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2 . The number of pelagic birds that
could be affected in open, offshore waters would depend on the extent and persistence of the
oil slick.

The recent Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been tr eated for oiling include several pelagic species such as the Northern Gannet

, Magnificent Frigatebird, and Masked Booby (International Bird Rescue Research Center, 2010). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.



### C.4.2 Shorebird s and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non

- endangered birds are also found along the northern Gul f C oast, including diving birds, shorebird s, marsh birds, wading birds, and
waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, flats, dunes, bars, barrier islands, and sim ilar habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull

- Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in recent lease sale EISs (MMS, 2007b, 2008).

The Brow n Pelican ( Pelecanus occidentalis ) was delisted from federal endangered status in 2009 (USFWS, 2010c). However, this species is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries an d Parks, 2011) and as a species of special concern by the State of Florida (Florida Fish and Wildlife ConservationSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 49 Commission, 2010). Brown Pelicans inhabit coastal habitats and forage within both coastal
waters and waters of the inner continental shelf. Aerial and shipboard surveys, including
GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans li ve in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010 b ).

The Southern Bald Eagle ( Haliaeetus leucocephalus ) was delisted from its threatened status in
the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern U.S., including coastal habitats along the Gulf of Mexico. The Gulf C oast is inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebird s and coastal nesting birds include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely
to affect shorebird s or coastal nesting birds, as the lease area is 223 miles (359 km) from the

n earest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2007

- G03 will minimize the potential for marine debris

- related impacts on shorebi rds.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas n ear Port Fourchon and Houma, Louisiana, where shorebird s and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between species and between individ uals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel pathways; known distances are from 20 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard

- powered boat (Rodger s and Schwikert, 2002). Flushing distances may be similar or less for the support vessels to be used for Anadarko’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreli ne, so disturbances to nesting birds, eggs, and chicks is not expected. Vessel operators will use designated navigation channels and comply with posted speed and wake restrictions while transiting sensitive inland
waterways. Due to the limited scope and short duration of drilling activities, any short

- term impacts are not expected to be biologically significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the typ e of aircraft, the bird species, the activities that animals were previously engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances for some species (B élanger and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91

- 36D recommends that pilots maintain a minimum altitude of 610 m (2,000 ft) when flying over

noise

- sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. This is greater than the distance (slant range) at which aircraft overflights have been reported to cause behavioral effects on most species of birds studied (Efroymson et al., 2000). With theseSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 50 guidelines in effect, it is lik ely that individual birds would experience, at most, only short

- term
behavioral disruption.



### Impacts of Large Oil Spill (WCD)

The revised OSRA modeling results ( BOEMRE, 2011 ) summarized in Section A.9.3 predict that
there is a 78% chance (in winter) that oi l from a spill in this lease area would reach shorelines in
Texas and a 60% chance (in spring) of contacting coastlines in Louisiana within 120 days.

Data from the Macondo spill provide additional information about the species of coastal birds that may be affected in the event of a catastrophic spill of a similar nature and duration. This information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds had been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, over 2,000 oiled birds have been collected alive and about 1,200 released (NMFS, 2010 c ). According
to the International Bird Rescue Research Cente r (2010), bird species that have been treated for oiling include the following:

• Brown Pelican

• White Pelican

• Masked Booby

• Magnificent Frigatebird

• Laughing Gull

• Herring Gull

• Northern Gannet

• Black Crowned Night Heron

• Tri

- colored Heron

• Green Heron

• Cattle Egre t

• Snowy Egret

• Reddish Egret

• Least Bittern

• Common Tern

• Royal Tern

• Caspian Tern • Sandwich Tern

• Forsters Tern

• Black Tern

• Gull

- billed Tern

• Least Tern

• Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling

• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead, oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and unidenti fied Tern. There are no reports of Bald Eagle oiling.

Coastal birds can be exposed to oil as they float on the water’s surface, dive during foraging, or wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they can ingest and inhale the oil on their bodies. Scavengers such a s Bald Eagles and gulls can be exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be dama ged if an oiled adult sits on the nest.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 51 As noted above, the Brown Pelican was recently removed from the endangered species list. Over 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in the event of a catastrophic spill reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup activities, and long

- term habitat contamination.



## C.5 Fish eries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater environment of the northern Gulf of Mexico. The biological oceanography of the region is dominated by the i nfluence of the Loop Current, whose surface waters are among the most oligotrophic in the world’s oceans. Superimposed on this low

- productivity condition are productive “hot spots” associated with entrainment of nutrient

- rich Mississippi River water and

m esoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an important role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabi ting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents (a small fuel spill and a large oil spill [WCD]).



### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish

- attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagi c fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (e.g., Holland et al., 1990; Higashi, 1994; Relini et al., 1994 MMS 2000, 2007b,

2008 ). This FAD effect could possibly enhance th e feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are considered minor.



### Impacts of Effluent Discha rges

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but should be diluted rapidly to undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges . Deck drainage from contaminated areas will be passed through an
oil

- and

- water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but should be diluted rapidly toSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 52 undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and
uncontaminated coo ling water, fire water, and ballast water

, are expected to be diluted rapidly and have little or no impact on water column biota.



### Impacts of Water Intakes

Seawater will be drawn from the ocean for once

- through, non

- contact cooling of machinery

on the drill ing rig. The rig planned for use in this EP is not a “new” facility as defined by the NPDES permit and therefore is not subject to the cooling water intake regulations for Phase III
facilities under Section 316(b) of the Clean Water Act

.

The intake of sea water for cooling water will entrain plankton. The low intake velocity should allow most strong swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, drifting plankton would not be able to escape entrainment with the exception of a few fast swimming larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily through changes in water temperature during the route from cooling intake structure to discharge structure and mechanical d amage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities , any short

- term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.



### Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resource s are discussed in recent EISs (MMS, 2007b, 2008)

. F or this EP , there are no unique site

- specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by Anad arko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will mitigate the potential for impacts on pelagic communities

, including ichthyoplankton. EP Section H pr ovides detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water sur face and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measur es. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depe nding on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton. Due to the limited areal extent and short duration of water quality impacts, small fuel spill would be unlikely to produc e detectable impacts on pelagic communities.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 53 

### Impacts of a Large Oil Spill (WCD)

A large oil spill could affect water column biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes are especially vulnerable to oiling because they inhabit the upper layers of the water column, and they will die if exposed to certain toxic fractions of spilled oil. Impacts would be potentially greater if local scale currents retained planktonic larval assemblages (and the floating oil slick)
within the same wat er mass.



### C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson

- Stevens Fishery Conservation and Management Act, as a mended, Federal agencies are required to consult on activities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fishery Management Councils.

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fi shery Management Plans for corals and coral reefs, shrimp s , stone crab s , spiny lobster s , reef fishes, coastal migratory pelagic fishes, and red drum s . In 2005, the EFH for these managed species was
redefined in Generic Amendment No. 3 to the various Fishe ry Management Plans (GMFMC, 2005). T he EFH for most of these GMFMC

- managed species is on the continental shelf in waters shallower than 183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps. EFH for corals and coral reefs includes some shelf

- edge topographic features on the Texas

- Louisiana OCS, the nearest of which are shelf edge topographic features in GB128 located approximately 131 miles (210 km) north of the lease area along the shelf edg e south of Louisiana.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfi shes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include those species and life stages listed
in Table 6

.

Table 6. Transient fish species that may be present in Sigsbee Escarpment Blocks 39 and 40 (From: N ational Marine Fisheries Service, 2009).

Species Life Stage

Blue marlin Juvenile and a dult

White marlin Juvenile and a dult Skipjack tuna Spawning
Yellowfin tuna Spawning

, j uvenile

, and a dult Bigeye t hresher s hark All Bigeye tuna Adult
Bluefin tuna Spawning, eggs, l arvae , and adult Longfin m ako s hark All

Oceanic w hitetip s hark All

Swordfish Larvae

, j uvenile

, and a dult Tiger s hark A dult

White marlin Juvenile and a dultSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 54 Recent research indicates the central and western Gulf of Mexico may be import ant spawning habitat for Atlantic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of th e HAPC is approximately 300,000 km 2 (15,000 mi 2 )

. The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern United States and Canadian coasts, followed by migration to the Gulf of Mexi co to spawn in April, May, and June (NMFS, 2009).

In 2005, a new amendment to the original EFH Generic Amendment was finalized (GMFMC, 2005). One of the most significant proposed changes in this amendment reduced the extent of
EFH relative to the 1998 Ge neric Amendment by removing the EFH description and
identification from waters between 100 fathoms and the seaward limit of the Exclusive Economic Zone ( EEZ )

. There are Fishery Management Plans in the Gulf of Mexico OCS region for shrimp s , red drum s , reef fishes, coastal migratory pelagics, stone crabs, spiny lobsters, coral s and coral reefs, billfish es , and highly migratory species. The Highly Migratory Species Fisheries Management Plan was recently amended to update EFH and HAPC for the bluefin tuna

spa wning area ( NMFS , 2009). There are current NTL’s (2009

- G39 and 2009

- G40) that provide guidance and clarification of the regulations with respect to biologically sensitive underwater
features and areas and benthic communities that are considered EFH (MMS, 2009 a,b ). A new EFH consultation has been initiated between BOEMRE’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation w ith the elements described

a bove will be the rule ( BOEMRE, 2011 ).

Other HAPCs have been identified in the Gulf of Mexico by the GMFMC (2005). These include the Florida Middle Grounds, Madison

- Swanson Marine Reserve, Tortugas North and South Ecological Res erves, Pulley Ridge, and several individual reefs and banks of the northwestern
Gulf of Mexico ( Figure 3 )

. The nearest of these is Rezak Sidner Bank

, located approximately

135 miles (218 km) north of the lease area.

Routine IPFs potentially affecting EFH include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents

– a small fuel spill and a large oil spill (WCD).



### Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structur e in the deepwater environment, will act as a n FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holl and et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS 2000, 2007b, 2008 ). This FAD effect would possibly enhance feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary str ucture, any impacts on EFH for highly migratory pelagic fishes are considered minor.



### Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling muds and cuttings, treated sanitary and domest ic wastes, deck drainage, and miscellaneous discharges such as desalination unit brine and uncontaminated cooling water, firewater, andSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 55 ballast water. Impacts on water quality have been discussed previously. No significant impacts

on EFH for highly migra tory pelagic fishes are expected from these discharges.



### Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope and s hort duration of drilling activities , any short

- term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically significant.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventat ive measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will help diminish the potential for impacts on EFH. EP Section H provides
detail on spill response measures. Given the o pen ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008)

. F or this EP

, there are no unique site

- specific is sues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depe nd on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the
lease area. A spill would also produce short

- term impact on water quality in the HAPC for spawning Atlantic bluefin tuna, which covers much of the deepwater Gulf of Mex ico. The areal extent of the affected area would represent a negligible portion of the HAPC.

A small fuel spill would not affect EFH for corals and coral reefs, the nearest EFH being the topographic features located approximately 131 miles (210 km) from t he lease area, along the shelf edge south of Louisiana. A small fuel spill would float and dissipate on the sea surface and
would not contact these features.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on EFH are discussed in recent EISs (M MS, 2007b, 2008). For this EP

, there are no unique site

- specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially the subsurface as well. Given the exte nt of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimp s , stone crab s , spiny
lobster s , reef fishes, coastal migratory pela gic fishes, and red drum s . It would result in adverseSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 56 impacts on water quality and water column biota including phytoplankton, zooplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloo r habitat for managed demersal fish and shellfish species.

T he lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or sublethal impacts on spawning tuna. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The nearest indentified de ep water coral sits is located approximately 54 miles (87 km)
north

- northeast of the lease area in Block SE 40. An accidental spill would be unlikely to affect
this area . A surface slick would not reach these features . A lthough there are reports of
subs urface plumes resulting from the use of subsea dispersant s during the Macondo spill , the distance and difference in water depth are factors that would make an impact unlikely

. Near

- bottom currents in the region are expected to flow along the isobaths (Now lin et al., 2001) and typically would not carry a plume up onto the continental shelf edge

.



## C.6 Archaeological Resources

C.6.1 Shipwreck Sites

BOEMRE has reexamined the analysis for archaeological resources presented in the

m ulti

- lease

- sale EIS and the 200 9

- 2012 Supplemental EIS (MMS 2007b and 2008)

. This Supplemental EIS is based on additional information available since the publication of these two
documents and in consideration of the Macondo oil spill event. Substantial new information
that alters the impact conclusion for archaeological resources presented in the m ulti

- lease

- sale
EIS and the 2009

- 2012 Supplemental EIS has come to light as a result of BOEMRE

- sponsored studies and industry surveys. Specifically, evidence of damage to significant cultur al resources (i.e., historic shipwrecks) has been shown to have occurred because of an incomplete knowledge of seafloor conditions in lease areas >200 m (656 ft) deep that have been exempted from high

- resolution surveys. Since significant historic shipwre cks have been recently discovered outside the previously designated high

- probability areas (some of which show evidence of impacts from permitted activities prior to their discovery), a survey will now be required prior to construction beginning in 2011 in the area of potential effect for all OCS operations as a requirement of the plan permit issued by BOEMRE

.

SE 39 and SE 40 are not on the list of leases with a high potential for historic shipwrecks . There were no indications of wrecks or other archaeolog ical resources detected during the site clearance survey ( AOA Geophysics Inc. , 2008)

. Anadarko will abide by the applicable requirements of NTL 2005

- G07, which stipulate that work be stopped at the project site should any previously undetected archaeologi cal resource be discovered after work has begun until appropriate surveys and evaluations have been completed.

Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. I mpacts of a large oil s pill (WCD) are the only IPFs considered. A small fuel spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 57 

### Impacts of a Large Oil Spill (WCD)

The MMS (2007b) estimate d that a severe subsurface blowout could resus pend and disperse
sediments within a 300

- m (984

- ft) radius. Because there are no historic shipwrecks in the lease area, this impact would not be relevant.

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect
archaeolo gical sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were report ed at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Join t Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact shipwreck sites beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending

on its exte nt, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the seafloor it could adversely affect their condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance
with NTL 2005

- G07 Anadarko will immediately halt operations, take steps to ensure that the site is not disturbed in any way

, and contact the Regional Supervisor, Leasing and Environment,
within 48 hours of its discovery. Anadarko w ould cease all operations within 305 m (1,000 ft) of the site until the Regional Director provides instructions on steps to take to assess the site’s potential historic significance and protect it.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. The revised OSRA modeling summarized in Table 3 predicts that there is a

78% probability of oil from a spill in the lease area reaching shorelines in Texas (in winter) within 120 days and a 60% probability of co ntacting coastlines in Louisiana (in spring) within 120 days. As noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from oil contact

an d contamination of the site and its environment.



### C.6.2 Prehistoric Archaeological Sites

Available evidence suggests that sea level in the northern Gulf of Mexico was at least 90 m (295 ft), and possibly as much as 130 m (427 ft), lower than present sea lev el during the period 20,000

- 17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand around 3,500 years B.P. (Pearson et al., 1986).

During periods that the continental shelf was exposed above se a level, the area was open to habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently accepted to be around 12,000 years B.P. (Aten, 1983). The sea

- level curve for the
northern Gulf of Mexico proposed by Coa stal Environments, Inc. (CEI) suggests that sea level at 12,000 years B.P. wo uld have been approximately 45

- 60 m (148

- 197 ft) below the present

- day sea level (CEI, 1977 and 1982). On this basis, the continental shelf shoreward of the 45

- to 60

- m (148

- to 197

- ft) bathymetric contours has potential for prehis toric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry date of prehistoric man into North America, the MMS adopted the 60

- m (197

- ft) wa ter depth as the seaward extent for archaeological site potential in Gulf of Mexico region (BOEMRE, 2011)

.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 58 W ater depth s in the wellsite areas are 2,541 to 2,612 m ( 8,336 to 8,569 ft)

– well beyond the

60

- m (197

- ft) depth contour used by BOEMRE as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archa eological resources because the oil would float and dissipate
on the sea surface.



### Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea bl owout. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius.

Along the northern Gulf C oast, prehistoric sites occur frequently along the barrier islands and
mainland coast and alo ng the margins of bays and bayous (MMS, 2007b). The revised OSRA modeling summarized in Table 3 predicts that there is a 78 % probability of oil from a spill in the lease area reaching shorelines in Texas (in winter) within 120 days and a 60% probability o f oil reaching Louisiana shorelines (in spring) within 120 days. If a spill did reach a prehistoric site along these shorelines it could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a si te (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).



## C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities are described in recent EISs (MMS, 2007b, 2008) and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. Generally, most of the northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerge d seagrass beds occurring in sheltered areas
behind the barrier islands and in estuaries.

Due to the distance from shore, there are no IPFs associated with routine activities that are likely to affect beaches and dunes, wetlands, seagrass beds, coastal wil dlife refuges, wilderness areas, or any other managed or protected coastal area. The support bases at Port Fourchon and

Houma are not in a wildlife refuge or a wilderness area. Potential impacts of support vessel traffic are addressed briefly below.

A sm all fuel spill in the lease area would be unlikely to affect coastal habitats, as the lease area is 223 miles (359 km) from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal wa ters prior to breaking up.



### Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support operations, including crew boats and supply boats as detailed in EP Section K

, may have a minorSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 59 incremental impact on coastal habitats or protected areas. Impacts will be mini mized by following the speed and wake restrictions in harbors and channels.



### Impacts of a Large Oil Spill (WCD)

Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b, 2008). Coastal habitats inshore of the project area includ e barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP , there are no unique site

- specific issues with respect to
coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that there is a 78 % probability of oil
fro m a spill in the lease area reaching shorelines in Texas (in winter) within 120 days and a

60% probability of oil reaching Louisiana shorelines (in spring) within 120 days.

The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries. National wildlife refuges and other protected

areas along the coast are discussed in the lease sale EIS (MMS, 2007b) and Anadarko ’s OSRP.
Coastal and near coastal wildlife refuges, wilderness areas , and state and national parks within the geographic range of the potential shoreline contacts after 120 days are listed in Table 7

.

Table 7. W ildlife refuges, w ilderness areas , and state and national parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEMRE, 2011)

.

County or Parish W ildlife Refuge, Wilderness Area, or State/National Park

Cameron County, Texas Lower Rio Gr ande Valley National Wildlife Refuge Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park Andy Bowie County Park Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas Lower Rio Grande Valley Na tional Wildlife Reserve Laguna Atascosa National Wildlife Reserve

Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Kl eberg County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine and Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park
Port Aransas Park

Miss ion

- Aransas National Estuarine Research Reserve

Aransas County, Texas Mission

- Aransas National Estuarine Research Reserve Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas Mission

- Aransas National Estuarine Research Rese rve Aransas National Wildlife Refuge Matagorda Island State Park Guadalupe Delta WMA

Welder Flats Coastal PreserveTable 7. (Continued.)

Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 60 County or Parish W ildlife Refuge, Wilderness Area, or State/National Park

Matagorda County, Texas Big Boggy NWR

Aransas NWR
Mad Island WMA

San Bernard NWR

Brazoria County, Texas San Bernard NWR

Pe ach Point WMA

Brazoria NWR Christmas Bay Coastal Preserve and Christmas Bay
State Park

Galveston County, Texas Galveston Island State Park

Brazoria NWR Apffel Park

Seawolf Park

Old Fort Travis Park
Atkinson Island WMA

Ft. Anahuc Park

An ahuac NWR

Mcfaddin NWR

Jefferson County, Texas Mcfaddin NWR

Sea Rim State Park Murphree WMA

Texas Point NWR

Cameron Parish, Louisiana Sabine NWR

Cameron Prairie NWR

Lacassine NWR
Little Pecan Island Natural Area

Peveto Woods Natural Are a Lower Neches WMA

Rockefeller WMA

Vermilion Parish, Louisiana Louisiana Rockefeller WMA Paul J. Rainey WMA

Terrebonne Parish, Louisiana Atchafalaya Delta WMA Mandalay NWR Isles Dernieres Barrier Islands Refuge

Pointe Au Chein WMA

Lafourche Parish, Louisiana Louisiana Pointe Au Chein WMA

Wisner WMA

Plaquemines Parish, Louisiana Salvador WMA

Jean Lafitte National Historical Park and Preserve

Delta NWR

Pass A Loutre WMA

Breton NWR
St. Bernard State Park

NWR = National Wildlife R efuge; WMA = Wildlife Management Area.

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (M MS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil

- and

- water mousse, or tarballs (MMS, 2007b). Oil is generally deposited onSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 61 beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist fo r several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation will experience
dieback. Th irty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacted wetlands are expected to be converted permanently to open

- water habitat. The critical concentration of oil is that concentra tion above which impacts to wetlands will be long

- term and recovery will take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. Critical concentrations of various oils are expected to vary broadly for wetla nd types and wetland plant species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b).



## C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEMRE has reexamined the analy sis for recreational and commercial fishing presented in

MMS 2007b and 2008 based on additional information and in consideration of the Macondo oil spill event. However, n o new information from previous EISs was found that would alter the potential impact s on commercial fishing (BOEMRE, 2011)

.
The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining ha s occurred historically in the project area, primarily during spring and

summer. I n August 2000, the Federal government closed two areas in the northeastern Gulf of Mexico to longline fishing (65 Federal Register 47214, 1 August 2000). The lease is outsi de of
the closure areas.

Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to retrieve it. Longlines are often set near oceanographic features such as fronts or downwellings, with the aid of sophisticated on

- board
temperature sen sors, depth finders, and positioning equipment. Vessels are 10 to 30 m (33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main homeports for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. Benthic species targeted by commercial fishers occur on the upper continentalSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 62 slope, well inshore of the project area. Royal red shrimp are caught by trawlers in water depths
of about 250 to 550 m (820 to 1,804 ft). Tilefish are caught by bottom longlining in water depths from about 165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rig s offshore Texas and Louisiana. Due to the distan ce from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights). Two potential accidents are also addressed below

– a small fuel spill and a large oil spill (WCD).



### Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 1999, a portion of a pelagic longline snagged on the acous tic Doppler current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident. Generally, longline fishers use radar and are aware of offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent discharges a re likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be min imized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the even t of a small fuel spill. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vessels oper ating in the lease area. A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

Potential spil l impacts on fishing activities are discussed in recent EISs (MMS, 2007b, 2008). For
this EP , there are no unique site

- specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the north ern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spi ll response measures. The recent MacondoSigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 63 spill provides information about the maximum potential extent of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010 d ). At its peak on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the EEZ in the Gulf of Mexico.



### C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially alleviate the potential for impacts. EP Section H provide s detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 223 miles (359 km) from the nearest shoreline and nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects. A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



### Impacts of a Large Oil Spill (WCD)

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel invo lved in the incident and those responding to the spill. The drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, the

met eorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, including skin contact or breathing VOCs . Crude oil is a highly flammable mate rial

, and any smoke or vapors from a crude oil fire can cause irritation, and in large quantities may pose a health
hazard.

Data from the recent Macondo spill provide relevant information about the types of health issues that may occur in the event of a la rge oil spill (Centers for Disease Control and Prevention, 2010a). Wildlife cleaning and rehabilitation workers have reported concerns including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildlife

- cleaning workers. Personnel working on offshore vessels or providing direct oversight to o ffshore vessels, including

USCG personnel, civilian contractors, and other responders who were expose d to oil and dispersants

, had a 7 to 12 times higher prevalence of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S such as headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010).Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 64 

### C.8.3 Employment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and infrastructure. The project involves drilling with support from exist ing shorebase facilities in

Louisiana . No new or expanded facilities will be constructed, and no new employees are expected to move permanently into the area. The project will have a negligible impact on socioeconomic conditions such as local employment, existing offshore and coastal infrastructure (including major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially mitigate and reduce the pot ential for impacts. EP Section H provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated wi thin a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.



### Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 20 07b, 2008).
For this EP , there are no unique site

- specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of w ork; it could result in temporary employment as part of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, in cluding service and support operations that are an important part of local economies.

The lease area is 223 miles (359 km) from the nearest shoreline. Based on revised OSRA modeling ( BOEMRE, 2011 ) as summarized in Section A.9.3 ( Table 3 )

, there is a 78 % c hance that oil from a spill in this lease area would reach shorelines in Texas (in winter) and a 60% chance of contacting shorelines in Louisiana (in spring) within 120 days. In addition to the analysis presented by MMS (2007b, 2008 ; BOEMRE, 2011 ), a rece nt study explored the economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater drilling (Inter

- Agency Economic Report, 2010). The study indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs along the Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion over a 6

- month period. This direct reduction in spending by the rigs affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spending (Inter

- Agency Economic Report, 2010)

.



### C.8.4 Recreation and To urism

BOEMRE has reexamined the analysis for recreation and tourism presented in MMS 2007b and

2008 based on additional information and in consideration of the Macondo oil spill event.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 65 However, n o new information from previous EISs was found that would al ter the potential impact s on recreation and tourism ( BOEMRE, 2011 ).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities due to the distance from shore. Compliance with NTL 2007

- G03 will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s prev entative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially help mitigate and reduce the potential for impacts.

EP Section H provide s detail on spill response m easures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are
no known recreational or tourism activities occurring in the lease area, and as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



### Impacts of a Large Oil Spill (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in recent EISs (MMS, 2007b, 2008). For this EP , there are no unique site

- specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the s pill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourag es people to stay away. Based on the
revised OSRA modeling ( BOEMRE, 2011 ) as summarized in Section A.9.3 ( Table 3 )

, there is a 78% chance that oil from a spill in this lease area would reach shorelines in Texas (in winter) and

a 60% chance of contacting s horelines in Louisiana (in spring) within 120 days.

In addition to the analysis presented by MMS (2007b, 2008), recent and ongoing studies have explored the economic impacts of the Macondo spill including tourism and “brand” damage (IEM, 2010; Oxford Econo mics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a 3

- year period at $22.7 billion (Oxford Economics, 2010)

.



### C.8.5 Land Use

Land use along the northern Gulf C oast is disc ussed in recent lease sale EISs (MMS, 2007b, 2008). There are no routine IPFs potential ly affecting land use. The project will use existing onshore support facilities in Louisiana . The land use at the existing shorebase sites is industrial. The project will not involve any new construction or changes to existing land use and, therefore, will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fr action of the level of activity occurring at the shorebase s

.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 66 A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.



### Impacts of a Large Oil Spill (WCD)

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A large spill could have limited temporary impacts on land use along the coast if additional staging areas were nee ded. For example, d uring the Macondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging

areas could be needed. These areas would eventually return to their original use as the response is demobilized.



### C.8.6 Other Marine Uses

The lease area is not located within any USCG

- designated fairway or shipping lane or Military Warning Area

. Anadarko will c omply with BOEMRE requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

The hazards survey did not identify any wells

, pipelines or flowlines, or other subsea facilities in the vicinity of the proposed w ellsites in SE 39 and SE 40 . The nearest wellhead is KC964 #1 located approximately 4.6 to 5.4 miles (7.4 to 8.7 km) north of the proposed wellsites and the nearest pipeline approximately 80 to 81 miles (129 to 130 km). There are no other known

marine us es of the lease area.

There are no IPFs from routine project activities that are likely to affect other marine uses. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses, as spill r esponse activities would be mainly within the lease area
and the duration would be brief.



### Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The block is not located within any U SCG

- designated fairway or shipping lane. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Anadarko will comply with BOEMRE requirements and lease stipulati ons to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure that no anchoring or seafloor

- disturbing activities occur near the exi sting pipelines and flowlines.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 67 

## D. Environmental Hazards

D.1 Geologic Hazards

The shallow hazards assessment conducted by AOA Geophysics Inc. (20 08 ) concludes that the
well site is free of any significant geological hazards and are suitable for the propose d activities.

See EP Section C for supporting geological and geophysical information.



## D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. Extreme weather, including high winds, strong curren ts, and large waves, was considered in the design criteria for the drilling rig. High winds and limited visibility during a severe storm could disrupt support activities (vessel and helicopter traffic) and make it necessary to suspend some activities on t he drilling rig for safety reasons until the storm or weather event passes. In the event of a hurricane, procedures as outlined in the Hurricane
Evacuation Plan would be adhered to.



## D.3 Currents and Waves

Metocean conditions such as sea states, wind speed , ocean currents, etc. will be continuously
monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions) and la rge waves were considered in the design criteria for the drilling rig. High waves during a severe storm could disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes.



## E. Alternatives

N o formal alternatives we re evaluated in this EIA for an EP . However, various technical and operational options

, including the location of the well site and the selection of a drilling unit

, were considered by Anadarko in developing the proposed action.



## F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and

BOEMRE lease stipulations and NTLs. The project will comply with all ap plicable F ederal, S tate, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by Anadarko’s OSRP and will
include the measures described in EP Sec tion H

.Sigsbee Escarpment Blocks 39 and 40 June 2011 Environmental Impact Analysis for Initial Exploration Plan Page 68 

## G. Consultation

No persons or agencies were consulted during the preparation of this EIA.



## H. Preparers

The EIA was prepared by CSA International, Inc. Contributors included

• M. John Thompson (Senior Scientist);

• Carlyle Kalloo (Senior Scientist) ;

• Neal Phillips, Ph.D. (Senior Scientist);

• Luis Lagera , Jr., Ph.D. (Senior Scientist);

• Bruce Graham (Senior Scientist);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director ) ; and

• Kim Dunleavy ( Technical Editor).



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### O ADMINISTRATIVE INFORMATION

(a) Proprietary Information

Proprietary copies of this plan contain inform ation not available to the public and include structure maps, seismic information, cross sections, depths of wells, etc.

(b) Bibliography

Shallow Hazards Report Final Sale Package for Western Gu lf of Mexico Sale Numbers 196.