-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 55675

keph2v

survey

vr16tm

survey

keph2v

survey

vr16tm

survey

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 5700

keph2v

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 6075

E 1,955,000E 1,960,000

W 92° 01' 00"

E 1,965,000

W 92° 00' 00"

E 1,970,000

W 91° 59' 00"

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 3485

W 92° 02' 00"

E 1,975,000E 1,980,000

E 1,955,000E 1,960,000

W 92° 01' 00"

E 1,965,000

W 92° 00' 00"

E 1,970,000

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 9095

W 92° 02' 00"

E 1,975,000E 1,980,000

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 Information

TR 8420 TR 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 6225

TR 3135

TR 8395
 

D 

HYDROGEN SULFIDE INFORMATION 

Discussions regarding geologic information are considered proprietary and have been omitted from this 

public copy EP. Wells nearby in Keathley Canyon Blocks 919, 292, 470 and 681 have tested similar 

age sections as the proposed locations, SE 39 “A”, ”B”, “C” and “D” and SE 40 “A”, “B” , “C”, and 

“D” locations without encountering any H2S. These wells include the 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 (Union Oil) 681 OCS-G 20949 #1. 

Since no (H2S) 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 approximately 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 depict 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 seafloor disturbances. 

(b) Topographic Features Map 

The proposed activities are not within 1,000 feet of a no-activity zone or within the 3-mile radius 

zone of an identified topographic feature. Therefore, no map is required 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 identified topographic feature. Therefore, the topographic features 

statement required by NTL No. 2008-G04 is not applicable. 

(d) Live Bottoms (Pinnacle Trend) Map 

The activities proposed in this plan are not within 200 feet of any pinnacle trend feature with 

vertical relief equal to or greater than 8 feet. 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 potentially 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 coverage”, and, therefore, under the guidance set 

out in NTL No. 2008-G06, a Remotely Operated Vehicle Monitoring Survey Plan is required. 

Pursuant to NTL 2008-G06, operators may be required to conduct remotely operated vehicle 

(ROV) surveys during the proposed 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 location 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 observations as described in the subject NTL and 

Form MMS-141 prior to commencing operations and prior to moving off location. The 

observations will be documented using Form MMS-141, or a facsimile 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 agencies must ensure that any 

actions they authorize, fund, or carry out are not likely 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 required to address site-specific 

information on the presence of federally listed threatened or endangered species and critical 

habitat designated under the ESA and marine mammals 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 that one or more of these species could be seen 

in the area of our operations. The following table reflects the Federally-listed endangered and 

threatened species in the lease area 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 Balaenoptera musculus E Xa -- None

Fin whale Balaenoptera physalus E Xa -- None

Humpback whale Megaptera novaeangliae E Xa -- None

North Atlantic right whale Eubalaena glacialis E Xa -- None

Sei whale Balaenoptera borealis E Xa -- None

Sea Turtles 

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, Eb X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys 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 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 Quality Information

This EP does not propose activities for which the State of Florida is an affected State. Therefore, 

the discussion required per NTL 2008-G04 is not applicable to this EP. 

(k) Socioeconomic Information 

The activities proposed in this plan are not located offshore Florida. Therefore, socioeconomic 

information required per NTL 2008-G04 is not applicable to this EP. 
 

F 

WASTE AND DISCHARGE INFORMATION 

The following estimates were prepared utilizing Anadarko’s experience with similar 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 wetted 

with 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/gals/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 bbls/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/day 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 

overboard 
 

Cuttings 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 personnel 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. Therefore, 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) Emission amount (in tons) associated with 

your proposed exploration activities more than 90% of the amounts calculated 

using the following formulas: CT = 3400D2/3 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. Per 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 Complex 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 

Amounts1

 (tons)

Calculated 

Exemption 

Amounts2 (tons)

Calculated 

Complex Total 

Emission 

Amounts3 (tons)

Particulate matter (PM) 190.50 7425.90 N/A 

Sulphur dioxide (SO2) 873.92 7425.90 N/A 

Nitrogen oxides (NOx) 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 

Amounts1

 (tons)

Calculated 

Exemption 

Amounts2

 (tons)

Calculated 

Complex Total 

Emission 

Amounts3

 (tons)

Particulate matter (PM) 192.35 7425.90 N/A 

Sulphur dioxide (SO2) 882.41 7425.90 N/A 

Nitrogen oxides (NOx) 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 and the Oil Spill Response Certification letter 

accepted by BOEMRE on July 27, 2011 for Anadarko Petroleum Corporation and its 

subsidiaries, Kerr-McGee Oil & Gas Corporation and Anadarko E&P Company L.P. (Company 

Numbers 00981, 02219 and 00148, respectively) 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 Clean Gulf Associates (CGA). Personnel would be 

obtained from the Marine Spill Response Corporation’s (MSRC) STARS network, including a 

supervisor to operate the equipment. 

In addition Anadarko has a contract with National Response Corporation (NRCC) for additional 

equipment. NRCC’s Independent Contractor Network (ICN) will provide the closest available 

personnel and additional equipment as needed. 

Anadarko is a member of the Helix Well Containment Group (HWCG), a combination of the 

Helix Fast Response System (HFRS) and the common equipment and services. This agreement 

allows access to subsea well containment and well shut-in equipment. 

Anadarko is also a member of the Marine Well Containment Company (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 30.1o 21 o 21 o 

* Note–for the OSRP exploratory worst case discharge scenario only the Area/Block is referenced in the OSRP. Exploratory drilling 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 response capabilities per previous discussions with Rusty Wright. 

Anadarko has determined that the worst-case scenarios from the activities proposed in this Initial 

EP do not supersede the worst-case scenario for Garden Banks Block 346. 

Since Anadarko has the capability to respond to the worst-case spill scenario included in our 

Regional OSRP, and since the worst-case scenarios 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 the maximum extent practicable, to a worst-case 

discharge, or a substantial threat of such a discharge, resulting from the activities proposed in our 

EP. 

(b) Worst-Case Discharge Volume Assumptions 

Worst-case discharge (WCD) calculations and assumptions within this section utilized guidelines 

and requirements pursuant with NTL No. 2010-N06. The following information summarizes the 

WCD scenario for Sigsbee Escarpment 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 analysis, the largest spill volume originating from the proposed 

activity would be an uncontrolled blowout of the well during 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 Initial 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 Analysis Model (OSRAM) for the Western Gulf of 

Mexico. Additional information may be referenced in the “Oil-Spill Risk Analysis: Contingency 

Planning Statistics for Gulf of Mexico OCS Activities” (OCS Report MMS 2004-026), using the 

average conditional probability for 3, 10, and 30 day impacts. 

Sigsbee Escarpment 39 is located within Launch 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 parish within the Gulf of Mexico for this operation. Matagorda 

County is located Texas and includes Big Boggy NWR, a portion of San Bernard NWR, and 

Mad Island Wildlife Management Area (WMA). Galveston County is also located in Texas and 

includes Galveston Island State Park, Brazoria National 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 located in Louisiana and includes 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 detection to equipment deployment on-site is included in 

Table H-3. The table estimates individual times needed 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 volume at 256,561 BOPD. An ADIOS 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 bbls) of the initial volume would be 

evaporated/dispersed within 24 hours. 

If approved and appropriate, 4 sorties (8,000 gallons) from the Basler aircraft 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 during Deepwater Horizon, 

approximately 5% (11,674 bbls) of the worst case discharge volume after natural 

evaporation/dispersion could potentially be burned. 

Although unlikely in a spill lasting 30 days, potential shoreline impact in Galveston and/or 

Matagorda County, and/or Cameron Parish could occur depending on environmental conditions 
 

(wind, currents and temperature) at the time of an incident. Nearshore response may include the 

use of shoreline boom on beach areas, or protection/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 and 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/dispersion at 24 hours. This amount could be further 

reduced through the application of aerial and subsea dispersants, provided such applications were 

approved. 

Anadarko’s contingency plan for dealing with this worst-case discharge 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 continuous support for the duration of the event. 

Response resources are activated and supplemented 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 Containment Group (HWCG), a combination of the 

Helix Fast Response System (HFRS) and the common equipment and services. This agreement 

allows access to subsea well containment and well shut-in equipment. 

Anadarko is also a member of the Marine Well Containment Company (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 emergency 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 spilled and calculate additional potential of oil 

flow. A continuous aerial surveillance program would be used to assess the growth of the 

slick and the volume of oil on the water. Observations of the size of the slick on the 

water, combined with observations at the source, 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 Unified 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 trajectories. If oil is seaward 

bound, going away from land, discuss additional strategies with Unified Command. 

 7. If oil is moving in the direction of a shoreline and weather conditions are favorable, 

request approval to utilize dispersants. 

 a. Prior to commencing application operations, conduct an on-site survey in consultation 

with natural resource specialists to determine if any threatened or endangered species 

are present in the projected application area 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 aircraft, 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 applied as soon after discharge as possible, since 

weathering of the oil decreases dispersant effectiveness. The estimated window of 

opportunity for most effective use of dispersants is within 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 the oil has been on the 

water for more than three days. Ultimately, 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 location 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 for long-duration, high-volume skimming. 

Based on average travel times, the HOSS 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 encounter 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 activated 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 vessels 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) would arrive on-scene between approximately 

21.25-27.25 hours of the initial release. 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 FRU has 200 barrels of on-board storage. 

Approval will be requested to decant water after gravity separation, through a hose 

forward of the skimmer, to optimize temporary storage capacity. A 42" Boom will be 

utilized to concentrate oil so that it is thick enough to be skimmed. 

 9. Dispersants, Fast Response Units (FRU), Oil Spill Response Vessels (OSRV or R/V) 

would typically work daylight hours only. 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, trajectories, 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 could be commenced again. Safety would 

remain the first priority. 

 10. Prepare Site-Specific Waste Management Plan, Site Safety Plan, Decontamination Plans, 

Communications and Medical Plans. 

 11. If oil becomes a threat to any shoreline, data from the aerial surveillance, weather reports, 

and trajectories would be used to direct onshore teams to deploy protection/containment 

boom with reference to Area Contingency Plans 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 Wildlife Rescue and Rehabilitation Plan. 
 

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

 Additional Oil Spill Removal Organization (OSRO) personnel to relieve equipment 

operators 

 Vessels for supporting offshore operations 

 Field safety personnel 

 Continued surveillance and monitoring of oil movement 

 Helicopter, video cameras 

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

 Barge to transport recovered oil from offshore skimming system, and temporary 

storage barges to onshore disposal sites that 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 transported from Houston to Houma or other potential 

command post locations 

- Communications equipment and technicians 

 Logistics needed to support 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 contain, to the maximum extent practicable as 

defined in 30 CFR 254.6 and 30 CFR 250.26(d)(1), to the estimated worst case discharge (WCD) 

associated with the proposed activity within 30 days. Deployment time for surface containment 

equipment is subject to availability and location, 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 details 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 during the Application for Permit to Drill (APD) 

process, including the Well Containment Screening 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 prevention, 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 BOPD 
 

Table H-2 

Trajectory by Land Segment 

Following are the average conditional probabilities (expressed as percent chance) that an oil spill starting at a 

particular launch area will contact a land 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 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

1 

1 

1 

1 

2 

1 

2 

1 

2 

1 
Table H-3 

WCD Scenario Drilling Activities – Based on a single well uncontrolled blowout (223 miles from shore) Sigsbee Escarpment 39 (Location “B”) 256,561 BOPD (initial volume) 233,471(after evaporation/dispersion) API Gravity 21 

Offshore Equipment from Spill Detection to Equipment Deployment Response Time: Sigsbee Escarpment 39

Offshore Equipment 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Tra

Tim

(Stag

Spi

(3

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

Basler Spray Aircraft DC 3 Spray Aircraft Aero Commander 

-- -- 

-- -- 

1 2 2 

ASI/Houma Houma 

0 0 1 1 1 1.7

HOSS Barge Operators Tugs 

43,000 4,000 1 

8 3 

CGA/Harvey STARS VOO 

Harvey 

1 2 4 4 0 42

OSRB Valiant Operators Tugs 

24,000 20,892 1 

6 1 

NRCC/Aransas Pass ICN VOO 

Aransas Pass 

0 2 2 1 4 57 

OSRB Defender Operators Tugs 

24,000 16,500 1 

6 1 

NRCC/Bayou La Batre ICN VOO 

Bayou La Batre 

0 2 2 1 4 64 

OSRB Energy Operators Tugs 

1,512 300 1 

4 1 

NRCC/Morgan City ICN VOO 

Morgan City 

0 2 2 1 4 26

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Ingleside STARS VOO 

Ingleside 

0 2 2 1 2 23.

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 2 19 

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Lake Charles STARS VOO 

Cameron 

.5 

2 2 1 2 20.

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Morgan City STARS VOO 

Morgan City 

.5 

2 2 1 2 17.

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Harvey STARS VOO 

Harvey 

.5 

2 2 1 2 20 

FRU Operators Utility Boat 

7,540 400 2 

12 

2 

CGA/Leeville STARS VOO 

Leeville 

.5 

2 2 1 2 17.

Spill Team Area Responders (STARS) called out by Marine Spill Response Corporation (MSRC) Independent Contractor Network (ICN) called out by National Response Corporation (NRCC) Vessel of Opportunity=VOO EMS=Enterprise Marine Services K-Sea=K-Sea Operating Partnership 
Offshore Equipment, cont. 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trav

Tim

(Stagi

Spil

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

FRU Operators Utility Boat 

7,540 400 2 

12 

2 

CGA/Venice STARS VOO 

Venice 

0 2 2 1 2 18.7

Koseq Skimming Arms Operators Vessel w/ storage/hull 

89,145 2,500 5 sets 

30 

5 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 12 19 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

53,487 1,500 3 sets 

18 

3 

CGA/Leeville STARS VOO 

Leeville 

0 2 2 1 12 17.2

Koseq Skimming Arms Operators Vessel w/ storage/hull 

17,829 500 1 set 

6 1 

CGA/Fourchon STARS VOO 

Fourchon 

0 2 2 1 12 16.2

Koseq Skimming Arms Operators Vessel w/ storage/hull 

35,658 1,000 2 sets 

12 

2 

CGA/Venice STARS VOO 

Venice 

0 2 2 1 12 18.7

DBL 101 Operators Tugs 

-- 107,285 1 

20 

4 

K-Sea/Atlantic Venice 

0 2 4 2 4 60 

DBL 102 Operators Tugs 

-- 107,285 1 

20 

4 

K-Sea/Atlantic Venice 

0 2 4 2 4 60 

CTCo2605 Operators Tug 

-- 20,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 44 

CTCo 5001 Operators Tug 

-- 47,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 44 

10,000' 42" Auto Boom VOO 

-- -- 40 

20 crew 

CGA/Harvey STARS Harvey .5 2 1 2 20 

5,000' 42" Auto Boom VOO 

-- -- 20 

10 crew 

CGA/Lake Charles STARS Cameron .5 2 1 2 20.2

5,000' 42" Auto Boom VOO 

-- -- 20 

10 crew 

CGA/Galveston STARS Galveston 0 2 1 2 19 

2,500' 42" Auto Boom VOO 

-- -- 12 

6 crew 

CGA/Ingleside STARS Ingleside 0 2 1 2 23.2

2,500' 42" Auto Boom VOO 

-- -- 12 

6 crew 

CGA/Pascagoula STARS Pascagoula 0 2 1 2 24.5 

2,700' 42" Boom VOO 

-- -- 12 

6 crew 

NRCC/Aransas Pass ICN Aransas Pass 0 2 1 2 23 

4,000' 42" Boom VOO 

-- -- 16 

8 crew 

NRCC/Corpus Christi ICN Corpus Christi 0 2 1 2 23.7

1,000' 42" Boom VOO 

-- -- 6 

3 crew 

NRCC/Bayou La Batre ICN Bayou La Batre 0 2 1 2 25.5 
Offshore Equipment, cont. 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trav

Tim

(Stagi

Spil

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

300' 42" Boom VOO 

-- -- 2 

1 crew 

NRCC/Morgan City ICN Morgan City 0 2 1 2 17.7

22,400' 42" Boom VOO 

-- -- 80 

25 crew AMPOL/New Iberia New Iberia 0 2 1 2 18.7

4,800' 42" Boom VOO 

-- -- 18 

9 crew AMPOL/Harvey Harvey 0 2 1 2 20 

Spotter Helo Surveillance Helo Hand Held Radios 

-- -- -- 

-- -- -- 

1 1 

30 

PHI/Fourchon PHI/Fourchon STARS 

Spill Site Spill Site Fourchon 

1 1 

1.5 

1 1 

1.5 

-- -- -- 

2.5 2.5 

3 

Total 322,561 330,562 
Nearshore Equipment from Spill Detection to Equipment Deployment Response Time: Sigsbee Escarpment 39

Nearshore Equipment* 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trave

Time 

(Stagin

Spill) 

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

Basler Spray Aircraft DC 3 Spray Aircraft Aero Commander 

-- -- 1 

2 2 

ASI/Houma Houma 

0 0 1 1 1 .75 

OSRV Admiral Operators 

24,000 300 1 

6 

NRCC/Galveston ICN Galveston 0 2 1 2 30 

OSRV Liberty Operators 

24,000 300 1 

6 

NRCC/Miami ICN Miami 0 2 1 4 67 

SWS Egmopol Operators 

3,000 100 1 

3 

CGA/Galveston STARS Galveston 0 2 1 2 50 

SWS Egmopol Operators 

3,000 100 1 

3 

CGA/Morgan City STARS Morgan City .5 2 1 2 17 

SWS Marco Operators 

3,588 34 1 

3 

CGA/Leeville STARS Leeville .5 2 1 2 6 

SWS Marco Operators 

3,588 20 1 

3 

CGA/Lake Charles STARS Cameron .5 2 1 2 36 

SWS Marco Operators 

3,588 34 1 

3 

CGA/Venice STARS Venice .5 2 1 2 13 

56' Nearshore Skimmer Operators 

21,500 250 1 

4 

CGA/Morgan City STARS Morgan City .5 2 1 2 17 

R/V Grand Bay Operators 

5,000 65 1 

3 

CGA/Venice STARS Venice .5 2 2 .5 4 

R/V RW Armstrong Operators 

5,000 65 1 

3 

CGA/Leeville STARS Leeville .5 2 2 .5 2 

R/V Bastian Bay Operators 

5,000 65 1 

3 

CGA/Lake Charles STARS Cameron .5 2 2 .5 9.5 

R/V Timbalier Bay Operators 

5,000 65 1 

3 

CGA/Galveston STARS Galveston 0 2 2 .5 13 

CTCo2603 Operators Tug 

-- 25,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 15 

CTCo 2604 Operators Tugs 

-- 20,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 15 

CTCo 2606 Operators Tugs 

-- 20,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 15 

CTCo 2607 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 15 

CTCo 2608 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 15 
Nearshore Equipment, cont.* 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trave

Time 

(Stagin

Spill) 

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

CTCo 2609 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 15 

8-Band Rope Mop Utility Boat 

2,283 100 1/4 

1 

NRCC/Galveston VOO Galveston 0 2 1 2 20 

4-Band Rope Mop Utility Boat 

1,509 100 1/4 

1 

NRCC/Morgan City VOO Morgan City 0 2 1 2 6.75 

Vikoma Cascade Utility Boat 

5,520 100 1/4 

1 

NRCC/Houston VOO Galveston 0 2 1 2 55.5 

Vikoma Cascade Utility Boat 

5,520 100 1/4 

1 

NRCC/Sulphur VOO Sulphur 0 2 1 2 38.5 

2,000' Beach Boom -- -- 6 CGA/Galveston Galveston 0 1 2 20 1,000' Beach Boom -- -- 4 CGA/Ingleside Ingleside 0 1 2 30.5 2,000' Beach Boom -- -- 6 CGA/Pascagoula Pascagoula 0 1 2 10.5 10,000' 18" Boom VOO 

-- -- 10/4 

1 Oil Mop/New Iberia New Iberia 0 2 1 1 9.25 

10,000' 18" Boom VOO 

-- -- 10/4 

1 Oil Mop/Houston Houston 1 2 1 1 22.5 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Port Arthur Port Arthur 0 2 1 1 17 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Houma Fourchon .5 2 1 1 5 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Port Allen Port Allen 0 2 1 1 9 

20,000' 18" Boom VOO 

-- -- 20 

8 crew Oil Mop/Belle Chasse Venice .5 2 1 1 5.5 

15,000' 18" Boom VOO 

-- -- 14 

6 crew Oil Mop/Gretna Gretna 0 2 1 1 5.5 

Wildlife Support Trailer -- -- 1/ 2 crew CGA/Harvey Harvey .5 1 2 2 Bird Scare Cannons -- -- 2 CGA/Venice Venice .5 1 2 3.5 Bird Scare Cannons -- -- 1 CGA/Galveston Galveston .5 1 2 6.5 Bird Scare Cannons -- -- 1 CGA/Ingleside Ingleside .5 1 2 10 Bird Scare Cannons -- -- 2 CGA/Lake Charles Cameron .5 1 2 5 Bird Scare Cannons -- -- 2 CGA/Pascagoula Pascagoula .5 1 2 3.25 Bird Scare Cannons -- -- 2 CGA/Harvey Harvey .5 1 2 2 Spotter Helo Surveillance Helo Hand Held Radios 

-- -- -- 

-- -- -- 

1 1 

30 

PHI/Fourchon PHI/Fourchon STARS 

Spill Site Spill Site Fourchon 

1 1 

1.5 

1 1 

1.5 

-- -- -- 

.5 .5 

3 

Total 121,096 135,798 

*Some equipment may be used offshore up to approximately 25 miles from shore 
 

H-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 Environmental 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, storms 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 the Marine Mammal Protection Act. 

Anadarko will operate in accordance with applicable regulations, including: 

NTL No. 2007-G02 – “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program” 

NTL No. 2007-G03 “Marine Trash and Debris Awareness and Elimination”, and 

NTL No. 2007-G04 “Vessel Strike Avoidance 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 turtles and if the operators activities are 

responsible remain available to assist in the recovery and comply with applicable 

mitigation measures when conducting seismic operations. It also requires 

operators to comply with applicable Notices 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 transported via a supply vessel as follows: 

a. Size of fuel supply vessel: 230 feet 

b. Carrying capacity of fuel 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 with 

syntheticbased 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 
Sigsbee Escarpment Blocks 39 and 40 

Environmental Impact Analysis for Initial Exploration Plan 

Figure 1. Vicinity map for the lease area.
 

L 

ONSHORE SUPPORT FACILITIES INFORMATION

(a) General 

Per NTL No. 2008-G04, the following tables reflect 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 primary service base cannot be utilized 

Anadarko will exercise the use of an alternate service base during drilling and/or 

completion operations. 

(b) Support Base 

No support base construction or expansion is planned for these activities. 

(c) Waste Disposal 

Disposed wastes describe those wastes generated by the proposed activity that are 

disposed of by means other than by release into 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 onshore 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 with 

syntheticbased 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 MANAGEMENT ACT INFORMATION 

Issues identified in the Louisiana Coastal Zone Management Program include the 

following: general coastal use guidelines, levees, linear facilities (pipelines); dredged soil 

deposition; shoreline modifications, surface 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 activities; 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 27779)

Sigsbee Escarpment Block 40 (OCS-G 27780)

Offshore Louisiana

June 2011

Prepared for:

Jill Fowler

Regulatory Analyst

Anadarko Petroleum Corporation

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) 219-3000
Sigsbee 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 Critical 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-Endangered 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 Shorebirds and Coastal Nesting Birds..............................................................................48
Contents

(Continued)

Page

Sigsbee Escarpment Blocks 39 and 40 June 2011

Environmental 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 Archaeological 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 Socioeconomic 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.............................................................................................................68
Sigsbee 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 Benthic 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 Kennicutt, 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 Escarpment Blocks 39 and 

40 (From: National Marine Fisheries Service, 2009) ...........................................................53

7 Wildlife refuges, wilderness areas, and state and national parks within the 

geographic range of the potential shoreline contacts after 120 days 

(From: 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........................43
Sigsbee 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 Management, 

Regulation and Enforcement

BOP blowout preventer

BOPD barrels of oil per day

B.P. before present

BPD barrels per day

CH4 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 capacity

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

NOx nitrogen oxides

NPDES National Pollutant Discharge Elimination 

System

NPS National Park Service

NRC National Research Council

NRCC National Response Corporation

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

SOx 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 Eastern Partnership
Sigsbee Escarpment Blocks 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) provides 

an analysis of environmental impacts based on the SHLs of these eight wellsites.

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) from 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 semisubmersible, 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 Operators (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 

Environmental Assessment (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 recent 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 

evaluating 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. Of 151 well blowouts in the Gulf of 

Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills. The total 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 production-related operations on the 

U.S. Outer Continental Shelf (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 blowout is estimated to be about once every 26 years.”
Sigsbee Escarpment Blocks 39 and 40 June 2011

Environmental Impact 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 Certification 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 blowout. Anadarko’s program meets the response planning requirements of 

the relevant coastal states and applicable Federal 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 describes 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.

This 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 NTLs 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 Information 

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 

company 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 Plans, 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 scenario 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-G39 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 Gulf 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 applicable 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 requirements 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 training, 

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-G03 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; and 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.
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A. Impact-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 activity 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 debris;

• 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 semisubmersible; 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 benthic communities.

The drilling vessel for the well proposed in this 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.
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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 & lights)

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 and 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 Protected 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 whales -- -- -- -- -- -- -- -- -- --

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)

Gulf sturgeon (threatened) -- -- -- -- -- -- -- -- -- X(6)

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

Coastal and Marine Birds

Marine birds X -- -- -- -- -- -- X X(6) X(6)

Shorebirds and coastal nesting birds -- -- -- -- -- -- -- X -- X(6)

Fisheries 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 sites -- --(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)

Socioeconomic 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.
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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) protected 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 greater 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 blocks.

(2) Activities with any bottom disturbance within an OCS lease block protected through 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 H2S concentrations greater than 500 ppm might be encountered. 

• Based on CFR 250.417(c), Anadarko is requesting that BOEMRE classify the area as “H2S absent.” 

Anadarko will submit an H2S 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 

determine 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 

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

• No impacts on archaeological resources are expected. The lease area is not on the list of high-probability 

blocks for shipwrecks and is well beyond 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 mammals, 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 tankers or barges.

• Not applicable.
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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 the wellbore (SHL) where the bottom template and 

blowout preventer (BOP) are located. Depending on the specific well configuration, this area is 

generally about 0.25 ha (0.62 ac).

Anchoring causes physical compaction of the seafloor beneath the anchor, and chains or lines 

can disturb the bottom as well as resuspend sediments 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 to 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 

fuels 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 (SOx), nitrogen oxides (NOx), volatile organic compounds (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 this 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

Effluent 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 (USEPA). 

Any discharges 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 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 synthetic-based drilling muds (SBMs) 

will be 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, uncontaminated fresh water and seawater, and ballast water.
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A.5 Water Intake

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 intake 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 (those 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 generated 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 Prevention 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 discharging 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 USEPA 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 outside 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, requires 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. 

No 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-trips 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) 
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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.

A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

• Small fuel spill, which is the most likely type of spill during OCS exploration activities; and

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

The following subsections summarize assumptions about the sizes and fates of these spills, as 

well as Anadarko’s spill response plans. Impacts are analyzed in Section 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, and this size is predicted to be the most common 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 for 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 (PAHs), 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 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 (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 effectiveness of spill response activities. 

However, given 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, the 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 changes in 
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the density, viscosity, and water content of the product spilled. It 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 coastal 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 would have a 9% or less probability of reaching the 

coastal areas of Louisiana within 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 

expected 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. Gulf 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 rates for the entire OCS are not anticipated 

(BOEMRE, 2011).

. In accordance with requirements of NTL 2010-N06, Anadarko has estimated a WCD 

for this EP as 256,561barrels 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 is 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. 

Anadarko will also comply with NTL 2010-N10 and the Interim Final Drilling Safety Rule, which 

specifies additional safety measures for OCS activities.

Spill Trajectory. The fate of a large oil spill in the lease area would depend on meteorological 

and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a 
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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 (Earthjustice, 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 

but 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 catastrophic 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 five hypothetical launch points in the 

Central and Western Gulf of Mexico Planning Areas. These launch point locations were 

deliberately placed in areas identified as having a high possibility of finding the largest oil 

volumes in each region. 

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf area 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. Western Gulf of Mexico slope area—lat. 27.51367 N, long. 94.51836 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 continue on a 

daily basis to help position equipment and human resources throughout the duration of any 

major spill or uncontrolled release.
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Table 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).

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 -- -- -- --

“--” = Values <0.5%; any areas where percent chance within 120 days of all seasons are all <0.5% are not shown.

Weathering. 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. The 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 stranding on shore or sedimentation to the 

seafloor (NRC, 2003).
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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 lost 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 then 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 with Applicable Regulations and Evaluation of 

Information Demonstrating Adequate Spill Response and Well Containment Resources:

. BOEMRE has issued recent NTL’s and guidance 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 facilities. 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 regulations, 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 

surface 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 OSRP; 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, explains 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 required 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); and (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 relief 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 ensure 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 Certification Letter per 

30 CFR 254.2(b) to BOEMRE on 15 June 2011. This plan contains detailed information on “Quick 

Response” procedures including:
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Environmental 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 access 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 capable of operating in shallow waters and the 

offshore/nearshore areas. These vessels have oleophilic brush pack skimming systems 

operating in troughs built into the hulls; below deck storage; and marine electronics packages 

including marine, aircraft and company 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 control 

room overlooking the skimmer deck. The estimated daily recovery capacity (EDRC) for the 

HOSS barge is approximately 43,000 barrels.

CGA is currently adding to its equipment stockpile, and has recently acquired 11 sets of 

Koseq skimming arms and two Aqua 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. NRCC 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 (OSRBs), Defender and 

Valiant, are equipped with spill containment and recovery gear to respond on request.

NRCC's Supplemental Offshore Skimming Systems (SOSSs) 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 and 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 single ram capping stack and 

dispersant injection capability for installation 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 for a detailed description of 

Anadarko’s site-specific response to the worst 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 common equipment and services of that
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Environmental Impact Analysis for Initial Exploration Plan Page 16

group. This 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 BOPD 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 stacks in addition to those available through MWCC.

A.9.4 Other Accidents Not Analyzed in Detail

The lease sale 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 are discussed briefly 

below along with a hydrogen sulfide (H2S) release. There 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 in 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 hydrates tend to form. Spill volumes are anticipated 

to remain about the same, but spill frequency can be expected to improve because of advances 

in subsea processing (BOEMRE, 2011).

Synthetic-based Fluid Spills. Synthetic-based fluids (SBF’s) have been used since 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 and 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 when 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 collisions 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 these 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 flow 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, while 
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Environmental Impact Analysis for Initial Exploration Plan Page 17

blowouts are considered to be 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 control. 

Measures 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. 

H2S Release. Pursuant to 30 CFR 250.490(c), Anadarko requests that the Regional Supervisor, 

Field Operations, classify the area in the proposed drilling operations as an area where H2S is 

absent. This request is also included in the EP. Based on this, no further discussion of H2S is 

warranted.

B. Affected Environment

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), water depths at 

the wellsites (Figure 2) in 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 communities near the wellsites (AOA Geophysics Inc., 2008).

A detailed description of the regional affected environment is provided in EISs prepared in 

2007 and 2008 (MMS, 2007b, 2008), including meteorology, oceanography, geology, air and 

water quality, benthic 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 were applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis 

Group, 2010a, b, c). Despite more limited 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 impossible 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 imagery (ESRI, 2010), the surface slick 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. Prior to the Macondo incident, water quality in deep, offshore 

waters of the Gulf of Mexico was 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 40 from those

predicted in the multi-lease-sale EISs (MMS 2007b, 2008; BOEMRE, 2011).
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Environmental Impact Analysis for Initial Exploration Plan Page 18

Figure 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 Impact Analysis for Initial Exploration Plan Page 19

C. Impact Analysis

This section analyzes the potential 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 for 

Gulf of Mexico deepwater operations and activities (MMS, 2000). The information in these 

documents is incorporated by reference. Potential site-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 status 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, 2011). Two metropolitan areas in Texas are nonattainment areas for 

8-h ozone (Dallas-Fort Worth, and Houston-Brazoria), and El Paso County is a nonattainment 

area for PM10 (USEPA, 2011).

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 southerly 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 calculations 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 large 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 potential impacts on air quality presented in 

previous multi-lease-sale EISs (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. 

Primary air pollutants typically associated with OCS activities are suspended PM, SOx, NOx, VOCs, 

and CO. Primary air pollutants typically associated with OCS activities are suspended PM, SOx, 
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Environmental Impact Analysis for Initial Exploration Plan Page 20

NOx, 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 

BOEMRE 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 (CO2) and methane (CH4) 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 CO2 emissions from all OCS activities in the 

2007-2012 leasing program are about 0.08% to 0.016% of the global CO2 emissions from fossil 

fuel combustion. Greenhouse gas emissions 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, 2007b) 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 (MMS, 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 any 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 Prevention 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 review 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 of a small spill on air quality are expected to be consistent with those analyzed 

and discussed in EISs prepared for lease sales in 2007 and 2008 (MMS, 2007b, 2008). The 

probability of a small spill would be minimized by Anadarko’s preventative measures during 
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Environmental Impact Analysis for Initial Exploration Plan Page 21

routine operations, including fuel transfer. In the unlikely event of a spill, implementation of 

Anadarko’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 those 

analyzed and discussed in the lease sale EISs (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 conditions 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 impacts 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 NOx, SOx, CO, and 

PM, as well as greenhouse gases. In situ burning would occur only after authorization 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 water 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 occurrences 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) from the Macondo spill site. Based the 

general circulation pattern seen in the Gulf of Mexico 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 affecting water quality are effluent discharges and two types of accidents: 

a small fuel spill and a large oil spill (WCD).
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Environmental Impact 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 down current 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 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. 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, little or no impact on water 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 overboard 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, little 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 water 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 of a small spill on water quality are expected to be consistent with those 

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, including 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 the 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 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. However, it is estimated that over 

90% of a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2). 
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Environmental Impact 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 fractions of diesel are dominated by two- and three-ringed PAHs, 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 so 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 spill 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 water quality are expected to be consistent with those 

analyzed and discussed in the lease sale EISs (MMS, 2007b, 2008). A large spill would affect 

water quality by producing a slick on the water surface and increasing 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. 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;). However, 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 (223 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% chance 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

Water 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 microseepages were seen within 

610 m (2,000 ft) of the wellsites (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 features 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 considered low (AOA Geophysics Inc., 2008).
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Environmental Impact 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 northeast 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 Wellsite C and 

3,810 m (12,500 ft) northeast of the Wellsite D. These features should be 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 

semisubmersible 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 Slope Habitats and Benthic Ecology study (Wei, 2006; 

Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area. 

The nearest 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 9,022 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. Benthic 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 Kennicutt, 2009).

Station

Distance to 

Lease Area 

(mi)

Water 

Depth (m)

Abundance

Meiofauna

(individuals/m2)

Macroinfauna

(individuals/m2)

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 1,600

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) 

densities in water depths representative of the lease area (2,440 to 2,635 m [8,005 to 8,645 ft]) 

typically range from approximately 84,000 to 157,000 individuals/m2 (Rowe and 

Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant 

groups in the meiofauna, accounting for about 90% of total abundance. 

The benthic macroinfauna is characterized by small mean individual sizes and low densities, 

both of which are a reflection of the meager primary production in Gulf of Mexico surface 

waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equation 
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Environmental Impact 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/m2

, 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 through 4), two of which are divided 

horizontally. The lease area is in Zone 3W and at the border of the 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, Paraonella 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 motile 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

Drilling 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, cuttings and seawater-based 

“spud mud” will be released at the seafloor. Excess cement slurry will 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 the 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 larval 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 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.

Discharges of washed SBM cuttings from the rig may 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 Associates, 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 

conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in 

concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may be 
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Environmental Impact Analysis for Initial Exploration Plan Page 26

adversely affected due to both the toxicity of the base fluid and organic enrichment (with 

resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease 

as opportunistic species that tolerate low oxygen and high H2S 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.

The areal extent of impacts from drilling discharges will be small. Assuming 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 coarse 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) indicated 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; BOEMRE, 2011). 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 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 persistence. 

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 features 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 bottom 

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 Schroeder, 2007; 

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic 

carbonates created by chemosynthetic communities.
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The nearest known chemosynthetic 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 

considered 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 Discharges

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 considered low. Monitoring 

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 this 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 the 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 high-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. Incubation experiments with environmental isolates demonstrated faster than expected 
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Environmental Impact Analysis for Initial Exploration Plan Page 28

hydrocarbon biodegradation 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 benthic 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 blowout. 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 organisms 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 

recreational 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 preliminary 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 brown 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 substance. 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 topographic 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) and typically would not carry a plume 

up onto the continental shelf edge.
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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 small 

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 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 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 stipulation, 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 

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) 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 includes 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 Coast are listed in Table 5. The table also indicates 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 

conservation. 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 Manatee.
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Table 5. Federally-listed endangered and threatened species in the lease area 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

West Indian manatee Trichechus manatus latirostris E -- X Florida (Peninsular)

Blue whale Balaenoptera musculus E Xa -- None

Fin whale Balaenoptera physalus E Xa -- None

Humpback whale Megaptera novaeangliae E Xa -- None

North Atlantic right whale Eubalaena glacialis E Xa -- None

Sei whale Balaenoptera borealis E Xa -- None

Sea Turtles

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, Eb X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys 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 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.

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 possible and potential 

impacts from the proposed leasing in the Western Gulf of Mexico Planning Area on 

endangered/threatened species and their designated critical habitat (MMS, 2007a,b). 

A biological assessment was prepared for each consultation. The formal ESA 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 associated 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 adversely 
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Environmental Impact 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 consultations 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. These 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 affected 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 marsh 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 (Physeter macrocephalus). Resident populations of sperm 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 correlated 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 movements 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 immatures, 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 that 

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).
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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 intermittent 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.

Current threats to sperm whale populations worldwide are discussed in a final recovery plan for 

the sperm whale recently published by NOAA (NMFS, 2010a). Threats are defined as “any factor 

that could represent an impediment to recovery” and these include fisheries interactions, 

anthropogenic noise, vessel interactions, contaminants 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 Gulf 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 good 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 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.

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 Central 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 insignificant 

(NMFS, 2007).

Drilling rig lighting and rig presence are not identified as IPFs 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 or 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 ft) 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 this 
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NTL will 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 sheltering 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 harassment 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 reactions 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 aircraft were short-term and probably of no long-term biological significance.

While 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 this altitude would minimize the 

potential for disturbing sperm whales. Therefore, no significant impacts are expected.

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 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 
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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 

toxic fumes; ingestion 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 small 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 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; 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 activity 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 disturbing these animals.

C.3.2 West Indian Manatee (Endangered)

Most 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 warmer 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 

spill (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 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 manatees.
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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 protected 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 disturbed 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 Louisiana 

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) 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 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 rare 
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Environmental Impact 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 scope 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 these mysticete whales as affected species in its Biological Opinion for the 

Five-Year Oil and Gas Leasing Program in the Central 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 14 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 below, and additional information on these groups is presented in the lease sale EIS 

(MMS, 2007b).

Mysticete whales. Two non-endangered mysticete whales are known from the Gulf of Mexico. 

The Bryde’s whale (Balaenoptera edeni) has been sighted most frequently 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 minke 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 temperate 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 whales 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). Any of these species could occur in the lease 

area.
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Delphinids

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 dispersion, 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 clymene), false killer whale (Pseudorca crassidens), Fraser’s dolphin

(Lagenodelphis hosei), killer whale (Orcinus orca), melon-headed whale (Peponocephala electra), 

pantropical spotted dolphin (Stenella attenuata), pygmy killer whale (Feresa attenuata), 

short-finned pilot whale (Globicephala macrorhynchus), Risso’s dolphin (Grampus griseus), 

rough-toothed dolphin (Steno bredanensis), spinner dolphin (Stenella longirostris), and striped 

dolphin (Stenella coeruleoalba). The most common non-endangered cetaceans 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 Rig 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 activities (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 IPFs 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 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 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/calf pairs, pods, or large assemblages of cetaceans are 

observed near an underway vessel, when safety permits. Compliance with this NTL will 
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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 (Würsig 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 preventative 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 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 

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 

toxic 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 spill, 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 foraging distribution and/or patterns, changing 
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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 marine 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)

Five 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 populations, which are listed 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 information and in 

consideration of the Macondo oil spill event. Information 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 

impacts on sea turtles. In most foreseeable cases, exposure to hydrocarbons persisting in the 

sea following the dispersal of an oil 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 

adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and nearshore 

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 area, 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, 2007b). 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 

anywhere 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 typically 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 impacts on 

sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature 
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Environmental Impact 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 Rig 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 routine 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 sea 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 cause 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, during 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 for 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 disturb 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 

expected.

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 Mexico 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 response 
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Environmental Impact 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 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 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 

toxic 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 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, inflammation, 

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 habitat, 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, implementation of Anadarko’s OSRP is expected to minimize the 

potential for these types of impacts on sea turtles. EP Section H provides detail on spill 

response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest 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 effects 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 contact oil 
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Environmental Impact 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 response 

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 therefore 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 result 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 sandy 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 large 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)

The lease area is 223 miles (359 km) from the nearest shorelines inhabited by Piping 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 the shoreline, as detailed in the OSRP.
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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 Gulf of Mexico reefs and banks and spawning Atlantic bluefin 

tuna; and critical habitat for beach mice, Gulf sturgeon, Piping Plover, and Whooping Crane.
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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-introduced 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 fields (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 Whooping Cranes as the lease area is approximately 

318 miles (511 km) from its critical habitat (Aransas NWR) and the revised OSRA modeling 

(BOEMRE, 2011) predicts a 3% probability (in spring) that an oil spill originating in this lease area 

would reach the Matagorda Island area of the Aransas NWR in Calhoun County, Texas, within 

30 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 areas 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 agencies 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, Florida 

(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 quality 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; Sulak 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) to Suwannee Sound, Florida 

(Levy County) (NMFS, 2010b) (Figure 3). A species description is presented in the lease sale EIS 
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(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 IPF 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 

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 Gulf sturgeon are discussed in the lease sale EISs (MMS, 2000, 

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 this species.

The lease area is about 302 miles (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 event 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 sturgeon 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 (Endangered)

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 recent 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 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)

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 modeling 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.
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In the event of oil contacting these beaches, beach 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 

sight 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 season when 

they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and 

shorebirds 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 distance from shore. For a 

discussion of shorebirds 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, shearwaters, and jaegers were the 

most frequently sighted seabirds in the deepwater area. From these surveys, four ecological 

categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants 

(e.g., shearwaters, storm petrels, and boobies); 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 Terns) (Hess and Ribic, 2000).

Common seabird species include Wilson’s Storm-Petrel (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 over the open ocean typically are <10 birds/km2

.

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 temporary 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 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 
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impacts on the birds due 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 rigs 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 offshore structures, resulting 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 

similar. 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; apparently the birds’ geomagnetic compass is upset by the 

red 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 effect 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 Mexico 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 Helicopter 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 significant.

Impacts of a Small Fuel Spill

Potential spill impacts on marine 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.

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 reduce the potential for impacts on marine and pelagic birds. 

EP Section 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 response measures. Section A.9.2 discusses the likely fate 
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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 fumes. 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 open 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 information from previous EISs was found that would alter 

the potential impacts 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, shearwaters, 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/km2

. 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 treated 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 Shorebirds 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 Gulf Coast, including diving birds, shorebirds, 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 similar 

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 Brown 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 and Parks, 2011) and as a 

species of special concern by the State of Florida (Florida Fish and Wildlife Conservation 
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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 live in the northern Gulf Coast, generally nesting on protected 

islands (USFWS, 2010b).

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 Coast is 

inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 

1992).

IPFs potentially affecting shorebirds 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 shorebirds or coastal nesting birds, 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 waters prior to breaking up. Compliance with NTL 2007-G03 will 

minimize the potential for marine debris-related impacts on shorebirds.

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas near Port Fourchon and Houma, 

Louisiana, where shorebirds 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 individuals (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 (Rodgers 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 shoreline, 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 type 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 (Bélanger 

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 these 
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guidelines in effect, it is likely 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 oil 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, 2010c). According 

to the International Bird Rescue Research Center (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 Egret

• 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 unidentified 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 as 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 damaged if an oiled adult sits on the nest.
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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 Fisheries 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 influence 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 

mesoscale 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 inhabiting 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 epipelagic 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 the 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 Discharges

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 to 
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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 cooling 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 drilling 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 seawater 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 damage (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 resources are discussed in recent EISs (MMS, 2007b, 2008).

For this EP, there are no unique site-specific issues with respect to spill impacts.

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 the potential for impacts on pelagic communities, including 

ichthyoplankton. EP Section 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 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 phytoplankton, zooplankton, and nekton. Due 

to the limited areal extent and short duration of water quality impacts, small fuel spill would be 

unlikely to produce detectable impacts on pelagic communities.
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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 water 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 amended, 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 Fishery Management 

Plans for corals and coral reefs, shrimps, stone crabs, spiny lobsters, reef fishes, coastal 

migratory pelagic fishes, and red drums. In 2005, the EFH for these managed species was 

redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 

2005). The 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 edge 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, billfishes, 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: National Marine Fisheries Service, 2009). 

Species Life Stage

Blue marlin Juvenile and adult

White marlin Juvenile and adult

Skipjack tuna Spawning

Yellowfin tuna Spawning, juvenile, and adult

Bigeye thresher shark All

Bigeye tuna Adult

Bluefin tuna Spawning, eggs, larvae, and adult

Longfin mako shark All

Oceanic whitetip shark All

Swordfish Larvae, juvenile, and adult

Tiger shark Adult

White marlin Juvenile and adult
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Recent research indicates the central and western Gulf of Mexico may be important 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 the HAPC is approximately 300,000 km2

(15,000 mi2). 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 Mexico 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 Generic 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 

shrimps, red drums, reef fishes, coastal migratory pelagics, stone crabs, spiny lobsters, corals

and coral reefs, billfishes, and highly migratory species. The Highly Migratory Species Fisheries 

Management Plan was recently amended to update EFH and HAPC for the bluefin tuna 

spawning 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, 2009a,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 with the elements described 

above 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 Reserves, 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 structure in the deepwater environment, will act as an 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 (Holland 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 structure, 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 domestic wastes, deck drainage, and miscellaneous 

discharges such as desalination unit brine and uncontaminated cooling water, firewater, and 
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ballast water. Impacts on water quality have been discussed previously. No significant impacts 

on EFH for highly migratory 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 short 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 preventative 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 open 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). For this EP, 

there are no unique site-specific issues 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 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 

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 Mexico. 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 the 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 (MMS, 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 extent 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 shrimps, stone crabs, spiny 

lobsters, reef fishes, coastal migratory pelagic fishes, and red drums. It would result in adverse 
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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 seafloor habitat for managed demersal fish and shellfish species.

The 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 deep 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. Although there are reports of 

subsurface plumes resulting from the use of subsea dispersants 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 (Nowlin 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 

multi-lease-sale EIS and the 2009-2012 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 multi-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 cultural 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 shipwrecks 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 archaeological 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 archaeological 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. Impacts of a large oil spill (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.
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Impacts of a Large Oil Spill (WCD)

The MMS (2007b) estimated that a severe subsurface blowout could resuspend 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 

archaeological 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 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 

shipwreck sites beyond the 300-m (984-ft) radius estimated by MMS (2007a, 2008), depending 

on its extent, 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 would 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 contacting 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 

and 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 level 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 sea 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 Coastal Environments, Inc. (CEI) suggests that sea level at 

12,000 years B.P. would 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 prehistoric 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) water depth as 

the seaward extent for archaeological site potential in Gulf of Mexico region (BOEMRE, 2011).
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Water depths 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 archaeological 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 blowout. 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 Coast, prehistoric sites occur frequently along the barrier islands and 

mainland coast and along 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 of 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 site (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 submerged 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 wildlife 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 small 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 waters 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 minor 
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incremental impact on coastal habitats or protected areas. Impacts will be minimized 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 include 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 

from 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. Wildlife refuges, wilderness areas, and state and national parks within the geographic 

range of the potential shoreline contacts after 120 days (From: BOEMRE, 2011).

County or Parish Wildlife Refuge, Wilderness Area, or

State/National Park

Cameron County, Texas

Lower Rio Grande 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 National 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

Kleberg 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

Mission-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 Reserve

Aransas National Wildlife Refuge

Matagorda Island State Park

Guadalupe Delta WMA

Welder Flats Coastal Preserve
Table 7. (Continued.)

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County or Parish Wildlife 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

Peach 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

Anahuac 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 Area

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 Refuge; 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 (MMS, 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 on 
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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 for 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. Thirty 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 concentration 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 wetland 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 analysis 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, no new information from previous EISs was found that would alter the 

potential impacts 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 has occurred historically in the project area, primarily during spring and 

summer. In 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 outside 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 sensors, 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 continental 
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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 rigs offshore Texas and Louisiana. Due to the distance 

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 acoustic 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 are 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 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 potential for impacts. EP Section 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.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event 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 operating 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 spill 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 northern 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 spill response measures. The recent Macondo 
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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, 2010d). At its peak on 12 July 2010, closures 

encompassed 217,821 km2 (84,101 mi2

), 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 provides 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 involved 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 

meteorological 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 material, 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 large 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 offshore vessels, including 

USCG personnel, civilian contractors, and other responders who were exposed 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 H2S such as headaches, dizziness, 

nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010).
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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 existing 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 potential for impacts. EP Section 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 that is dissipated within 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, 2007b, 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 work; 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, including 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% chance 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 recent 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 Tourism

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.
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However, no new information from previous EISs was found that would alter the potential 

impacts 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 preventative 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 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 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 spill 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 encourages 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 shorelines 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 Economics, 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 Coast is discussed in recent lease sale EISs (MMS, 2007b, 

2008). There are no routine IPFs potentially 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 fraction of the level of activity 

occurring at the shorebases.
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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 needed. For example, during 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 comply 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 wellsites 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 uses 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 response 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 USCG-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 

stipulations 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 existing 

pipelines and flowlines.
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D. Environmental Hazards

D.1 Geologic Hazards

The shallow hazards assessment conducted by AOA Geophysics Inc. (2008) concludes that the 

wellsite is free of any significant geological hazards and are suitable for the proposed 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 currents, 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 the 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 large 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

No formal alternatives were evaluated in this EIA for an EP. However, various technical and 

operational options, including the location of the wellsite 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 applicable Federal, State, 

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 Section H.
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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 information 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 Gulf of Mexico Sale Numbers 196.