UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - N-09662

Type - Initial Exploration Plan

Lease(s) - OCS-G32678 Block - 416 Walker Ridge Area

OCS-G32688 Block - 460 Walker Ridge Area

Operator - ConocoPhillips Company

Wells A, B and D

DRILLSHIP

Attached is a copy of the subject plan for public comments on issues that 

should be addressed in an Environmental Assessment.

It has been deemed submitted as of this date and is under review for approval.

Chiquita Hill

Plan Coordinator

Description -

Rig Type -

Subject:

From:

October 25, 2012
 PUBLIC INFORMATION 

August, 2012 

INITIAL EXPLORATION PLAN 

Lease Number(s): OCS-G 32678/32688 

Area/Block: Walker Ridge Blocks 416 and 460 

Prospect Name: Thorn

Offshore: Louisiana

Submitted by: ConocoPhillips Company 

600 North Dairy Ashford Road 

 Houston, Texas 77079-1175 

Bruce R. Wilcoxon 

 (281) 293-5337 

Bruce.R.Wilcoxon@ConocoPhillips.com 

Estimated startup date: January, 2013 

Authorized Representative: No. of Copies Being Submitted: 

Jodie Connor or Judy Davidson Proprietary: 1 & CD 

J. Connor Consulting, Inc. Public Info: 1 & CD 

16225 Park Ten Place, Suite 700 

Houston, Texas 77084 For BOEM: 

(281) 578-3388 Plan No. 

jodie.connor@jccteam.com or 

judy.davidson@jccteam.com 

Assigned to: 
RECORD OF CHANGES 

Date Section Page Remarks 

08/21/12 All All Submittal of Initial EP 

09/12/12 F Attachment 

F-1 

Waste Discharge Table was amended to include 

completion fluids. 

 L Attachment 

L-1 

Onshore Waste Disposal Table was amended to revise 

the disposal method for recyclable trash and debris to 

recycle. 

09/20/12 L Attachment 

L-1 

Onshore Waste Disposal Table was revised to amend 

Trash and Debris (non-recyclable) to a total of 120,000 

bbls per well, and Trash and Debris (non-recyclable) to 

burial. 
CONOCOPHILLIPS COMPANY

INITIAL EXPLORATION PLAN 

LEASES OCS-G32678 AND 32688 

 WALKER RIDGE BLOCKS 416 AND 460 

SECTION A Plan Contents 

SECTION B General Information

SECTION C Geological, Geophysical Information

SECTION D H2S Information 

SECTION E Biological, Physical and Socioeconomic Information

SECTION F Wastes and Discharge Information 

SECTION G Air Emissions Information

SECTION H Oil Spills Information

SECTION I Environmental Monitoring Information 

SECTION J Lease Stipulations Information 

SECTION K Environmental Mitigation Measures Information 

SECTION L Support Vessels and Aircraft Information 

SECTION M Onshore Support Facilities Information 

SECTION N Coastal Zone Management Act (CZMA) Information 

SECTION O Environmental Impact Analysis

SECTION P Administrative Information 
List of Attachments 

Attachment A-1 OCS Plan Information Form 

Attachment A-2 Well Location Plat 

Attachment A-3 Bathymetry Map 

Attachment A-4 Pay.Gov Receipt 

Attachment B-1 Blowout Scenario 

Attachment C-1 Structure Map 

Attachment C-2 Seismic Lines 

Attachment C-3 Cross Sections 

Attachment C-4 Shallow Hazards Assessment 

Attachment C-5 Stratigraphic Column 

Attachment C-6 Isopach Map 

Attachment E-1 Biological Map 

Attachment F-1 Generated Wastes Table 

Attachment H-1 Spill Response Discussion 

Attachment L-1 Wastes Transported To Shore Table 

Attachment L-2 Vicinity Map 

Attachment N-1 Louisiana Coastal Zone Management Certification 
SECTION A 

PLAN CONTENTS 

(A) PLAN INFORMATION FORM 

ConocoPhillips Company (ConocoPhillips) was awarded Walker Ridge Blocks 416 and 460 at 

Central Gulf of Mexico Sale Number 206. The lease expiration date for both leases is July 31, 

2018. To date, no operations have been conducted on these two blocks.

Under this initial EP, ConocoPhillips proposes to drill, test and complete three wells. Additional 

operations which will be covered under this Initial EP include the setting of a subsea wellhead 

over the proposed well locations. 

These wells will be drilled with a Dynamically Positioned Drillship and will involve a subsea 

BOP stack. Subsea wellheads will be installed with the drilling unit on location. See attached 

OCS Plan Information Form included as Attachment A-1. 

(B) LOCATION 

Included as Attachment A-2 is a Well Location Map depicting the proposed surface and bottomhole locations of the proposed wells. Also included as Attachment A-3 is a Bathymetry Map 

showing the water depths across the lease blocks and the locations of the proposed wells. 

(C) SAFETY AND POLLUTION PREVENTION FEATURES

Safety features on the drilling unit will include well control, pollution prevention, and blowout 

prevention equipment as described in 30 CFR Part 250, Subparts C, D, E, and O; and as further 

clarified by BSEE Notices to Lessees, and current policy making invoked by the BOEM, BSEE, 

Environmental Protection Agency and the U.S. Coast Guard. Schematics of the BOP and control 

system will be provided with the Applications for Permit to Drill as required by NTL No. 2010-

N10. An approved welding procedure and schematic of the location of the designated safe 

welding areas will also be available on the rig. 

The rig will be equipped with safety and fire-fighting equipment required to comply with USCG 

and ABS requirements. Appropriate life saving equipment such as life rafts, life jackets, ring 

buoys, etc., as prescribed by the U.S. Coast Guard, will be maintained on the rig at all times. 

Pollution prevention measures include installation of curbs, gutters, drip pans, and drains on 

drilling deck areas to collect all contaminants and debris. Compliance will be maintained with 

the EPA NPDES Permit which covers the leases. The rig will be monitored daily and any waste 

or fuel resulting in pollution of the Gulf waters will be reported to the representative in charge 

for immediate isolation and correction of the problem. Any spill will be reported to the 

appropriate governmental agencies. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page A-1 

 Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
ConocoPhillips Company August, 2012 

Initial Exploration Plan Page A-2 

 Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

(D) STORAGE TANKS AND/OR PRODUCTION VESSELS 

All facility tanks of 25 barrels or more: 

Type of 

Storage Tank 

Type of 

Facility 

Tank Capacity 

(bbls) 

Number 

of Tanks 

Total 

Capacity 

(bbls) 

Fluid 

Gravity 

(API) 

 Fuel oil 

 (Marine Diesel) Drillship 32,000 3 96,000 32.4°

(F) ADDITIONAL MEASURES 

ConocoPhillips does not propose additional safety, pollution prevention, or early spill detection 

measures beyond those required by 30 CFR 250. 

(G) COST RECOVERY FEE 

Included as Attachment A-4 is a Pay.Gov receipt in the amount of $10,326.00 (Agency Tracking 

Number 74335790394). 
U.S. Department of the Interior OMB Control Number: 1010-0151 

Minerals Management Service OMB Approval Expires: July 31, 2008

OCS PLAN INFORMATION FORM 

GENERAL INFORMATION 

Type of OCS Plan: X Exploration Plan (EP) Development Operations Coordination Document (DOCD) 

Company Name: ConocoPhillips Company BOEM Operator Number: 00056 

Address: 

600 North Dairy Ashford Road 

Contact Person: Jodie Connor or Judy Davidson 

Houston, Texas 77079 Phone Number: (281) 578-3388 

 Email Address: Jodie.Connor@jccteam.com or 

Judy.Davidson@jccteam.com 

Lease(s):32678/32688 Area: WR Block(s): 416/460 Project Name (If Applicable): Thorn 

Objective(s): Oil Gas Sulphur Salt Onshore Base: Fourchon, LA Distance to Closest Land (Miles): 171 

Description of Proposed Activities (Mark all that apply) 

 Exploration drilling Development drilling 

 Well completion Installation of production platform 

 Well test flaring (for more than 48 hours) Installation of production facilities 

 Installation of caisson or platform as well protection structure Installation of satellite structure 

 Installation of subsea wellheads and/or manifolds Commence production 

 Installation of lease term pipelines Other (Specify and describe) 

Have you submitted or do you plan to submit a Conservation Information Document to accompany this plan? Yes X No 

Do you propose to use new or unusual technology to conduct your activities? Yes X No 

Do you propose any facility that will serve as a host facility for deepwater subsea development? Yes X No 

Do you propose any activities that may disturb a BOEM-designated high-probability archaeological area? Yes X No 

Have all of the surface locations of your proposed activities been previously reviewed and approved by BOEM? Yes X No 

Tentative Schedule of Proposed Activities 

Proposed Activity Start 

Date 

End Date No. of 

Days 

Drill, complete and install subsea wellhead and TA Well Location A 01-01-13 04-27-13 116 

Drill, complete and install subsea wellhead and TA Well Location B 01-01-14 04-27-14 116 

Drill, complete and install subsea wellhead and TA Well Location D 01-01-15 04-27-15 116 

Description of Drilling Rig Description of Production Platform 

 Jackup Drillship Caisson Tension leg platform 

 Gorilla Jackup Platform rig Well protector Compliant tower 

 Semisubmersible Submersible Fixed platform Guyed tower 

 DP Semisubmersible Other (Attach Description) Subsea manifold Floating production system 

 Drilling Rig Name (If Known): Spar Other (Attach description) 

Description of Lease Term Pipelines 

From (Facility/Area/Block) To (Facility/Area/Block) Diameter (inches) Length (Feet) 

 BOEM Form BOEM-137 (October 2011 - Supersedes all previous editions of form BOEM-0137 which may not be used. 

*Collection has been submitted to OMB and is automatically renewed each month until approval.)

ATTACHMENT A-1
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one ConocoPhillips of this page for each proposed well/structure 

BOEM Form BOEM-137 (October 2011 - Supersedes all previous editions of form BOEM-0137 which may not be used. 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): A Subsea Completion 

Anchor Radius (if applicable) in feet: NA Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS-G 32688 

Area Name WR 

Block No. 460 

Blockline 

Departures 

(in feet) 

N/S Departure: 2,622’ FNL 

E/W Departure: 2,457’ FEL 

Lambert X-Y 

coordinates 

X: 2,310.183’ 

Y: 9,628.098’ 

Latitude/ 

Longitude 

26o 31’ 09.16” 

90o 57’ 04.84” 

 TVD (Feet): MD (Feet Water Depth (Feet):-6,915 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to 

inform you that BOEM collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for BOEM approval. We use the information to facilitate our review and data entry for OCS 

plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 550.197. An agency may not 

conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid 

Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form 

is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate 

that burden to average 600 hours per response, or 640 with an accompanying EP (1,000 hours in AKOCSR), or 690 (1,700 in 

AKOCSR) with an accompanying DPP or DOCD including the time for reviewing instructions, gathering and maintaining data, 

and completing and reviewing the forms associated with subpart B. Direct comments regarding the burden estimate or any other 

aspect of this form to the Information Collection Clearance Officer, Bureau of Ocean Energy Management, 381 Elden Street, 

Herndon, VA 20170.
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one ConocoPhillips of this page for each proposed well/structure 

BOEM Form BOEM-137 (October 2011 - Supersedes all previous editions of form BOEM-0137 which may not be used. 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): B Subsea Completion 

Anchor Radius (if applicable) in feet: NA Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS- G 32688 

Area Name WR 

Block No. 460 

Blockline 

Departures 

(in feet) 

N/S Departure: 2,624’ FNL 

E/W Departure: 832’ FEL 

Lambert X-Y 

coordinates 

X: 2,311,808’ 

Y: 9,628,096’ 

Latitude/ 

Longitude 

26o 31’ 08.88” 

90o 56’ 46.95” 

 TVD (Feet): MD (Feet): Water Depth (Feet):-6,965 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to 

inform you that BOEM collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for BOEM approval. We use the information to facilitate our review and data entry for OCS 

plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 550.197. An agency may not 

conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid 

Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form 

is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate 

that burden to average 600 hours per response, or 640 with an accompanying EP (1,000 hours in AKOCSR), or 690 (1,700 in 

AKOCSR) with an accompanying DPP or DOCD including the time for reviewing instructions, gathering and maintaining data, 

and completing and reviewing the forms associated with subpart B. Direct comments regarding the burden estimate or any other 

aspect of this form to the Information Collection Clearance Officer, Bureau of Ocean Energy Management, 381 Elden Street, 

Herndon, VA 20170.
OCS PLAN INFORMATION FORM (CONTINUED) 

Include one ConocoPhillips of this page for each proposed well/structure 

BOEM Form BOEM-137 (October 2011 - Supersedes all previous editions of form BOEM-0137 which may not be used. 

Proposed Well/Structure Location 

Well or Structure Name/Number (If renaming well or structure, reference previous name): D Subsea Completion 

Anchor Radius (if applicable) in feet: Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. OCS- G 32678 

Area Name WR 

Block No. 416 

Blockline 

Departures 

(in feet) 

N/S Departure: 4,125’ FNL 

E/W Departure: 2,880’ FEL 

Lambert X-Y 

coordinates 

X: 2,309,760’ 

Y: 9,642,435’ 

Latitude/ 

Longitude 

26o 33’ 31.18” 

90o 57’ 06.97” 

 TVD (Feet): MD (Feet): Water Depth (Feet):-7,195 

Anchor Locations for Drilling Rig or Construction Barge (If anchor radius supplied above, not necessary) 

Anchor Name 

or No. Area Block X Coordinate Y Coordinate Length of Anchor 

Chain on Seafloor

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

 X = Y = 

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to 

inform you that BOEM collects this information as part of an applicant’s Exploration Plan or Development Operations 

Coordination Document submitted for BOEM approval. We use the information to facilitate our review and data entry for OCS 

plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 550.197. An agency may not 

conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid 

Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form 

is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate 

that burden to average 600 hours per response, or 640 with an accompanying EP (1,000 hours in AKOCSR), or 690 (1,700 in 

AKOCSR) with an accompanying DPP or DOCD including the time for reviewing instructions, gathering and maintaining data, 

and completing and reviewing the forms associated with subpart B. Direct comments regarding the burden estimate or any other 

aspect of this form to the Information Collection Clearance Officer, Bureau of Ocean Energy Management, 381 Elden Street, 

Herndon, VA 20170.
±

3® 3

3

3

3® 3

3

3

Proposed WR460-A Well

90°59'0"W90°58'0"W90°57'0"W

26°31'0"N

26°30'0"N

26°29'0"N

2,300,0002,305,0002,310,000

9,615,000

9,620,000

9,625,000

9,630,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters

Chart Scale 1" = 2,000'

Well Location Plat - Public Information

Walker Ridge 460

G32688

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD

WR460-A SL 2,622ft FNL 2,457ft FEL 2,310,183 9,628,098 26° 31' 09.16"N 90° 57' 04.84"W -6,915

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD

WR460-B SL 2,624ft FNL 832ft FEL 2,311,808 9,628,096 26° 31' 08.88"N 90° 56' 46.95"W -6,965

Proposed Location - WR460-A

Proposed Location - WR460-B

Proposed 

WR460-B Well
±

3® 3

3

3

3® 3

3

3

3® 3

3

3

Proposed WR416-D Well

90°59'0"W90°58'0"W90°57'0"W

26°34'0"N

26°33'0"N

26°32'0"N

2,300,0002,305,0002,310,000

9,630,000

9,635,000

9,640,000

9,645,000

0 1,000 2,000 500 Feet

0 250 500 125 Meters

Chart scale 1" = 2,000'

Well Location Plat - Public Information

Location Call N/S Call E/W X Coordinate Y Coordinate Latitude Longitude WD

WR416-D SL 4,125ft FNL 2,880ft FEL 2,309,760 9,642,435 26° 33' 31.18"N 90° 57' 06.97"W -7,195

Proposed Location - WR416-D

Walker Ridge 416

G32678
±

3® 3

3

3

3® 3

3

3

3® 3

3

3

-7200

-7150

-7100

-7050

-7000

-6950 -6900 -6850

-6800

-7100

-7200

-7050

-7050

-7150

-7100

-7000

-6950

90°57'0"W90°58'0"W90°59'0"W

26°34'0"N

26°33'0"N

26°32'0"N

2,300,000

2,305,0002,310,000

9,630,000

9,635,000

9,640,000

9,645,000

0 500 1,000 2,000 Feet

0 125 250 500 Meters

Chart scale 1" = 2,000' Bathymetry Plat

Proposed WR416-D

X: 2,309,760

Y: 9,642,435

FEL of WR 416: 2,880ft

FNL of WR 416: 4,125ft

Walker Ridge 416

G32678

Universal Transverse Mercator Zone 15 North, US Feet

Spheroid Clarke 1866, 

Datum North American Datum 1927

Prime Meridian Greenwich

False Easting 1,640,416.666667

False Northing 0

Meridian Scale Factor 0.9996

Origin Latitude 0.0000

Origin Longitude -93.0000
±

3® 3

3

3

3® 3

3

3 -7000

-6950

-7050

-6900

-7100

-6850

-7150

-6800

-6750

-7200

-6700

-6750

-6900

-6850

-6850

-6850

-6800

-6950

-7000

-6850

-6950

-6850

-6850

-6950

-6950

-6800

-6800

90°57'0"W

90°58'0"W

90°59'0"W

26°31'0"N

26°30'0"N

26°29'0"N

2,300,000

2,305,000

2,310,000

9,615,000

9,620,000

9,625,000

9,630,000

0 500 1,000 2,000 Feet

0 125 250 500 Meters

Chart scale 1" = 2,000'

Proposed WR460-A

X: 2,310,183

Y: 9,628,098

FEL of WR 460: 2,457ft

FNL of WR 460: 2,622ft

Proposed WR460-B

X: 2,311,808

Y: 9,628,096

FEL of WR 460: 832ft

FNL of WR 460: 2,624ft

Walker Ridge 460

G32688

Bathymetry Plat

Universal Transverse Mercator Zone 15 North, US Feet

Spheroid Clarke 1866, 

Datum North American Datum 1927

Prime Meridian Greenwich

False Easting 1,640,416.666667

False Northing 0

Meridian Scale Factor 0.9996

Origin Latitude 0.0000

Origin Longitude -93.0000
Online Payment

Step 3: Confirm Payment 1 | 2 | 3

Pay.gov Tracking Information 

Payment Summary 

Thank you. 

Your transaction has been successfully completed.

Application Name: BOEM Exploration Plan - BF

Pay.gov Tracking ID: 257C499P

Agency Tracking ID: 74335790394

Transaction Date and Time: 07/17/2012 18:33 EDT

Address Information

Account Holder 

Name: jon gaynor 

Billing Address:

17407 

Saddlebrush tr. 

Billing Address 

2:

City: Houston 

State / Province: TX 

Zip / Postal 

Code: 77095 

Country: USA 

Account Information

Card Type: Visa 

Card

Number: ************3620 

Region: Gulf of Mexico 

Contact: 

Bruce Wilcoxon 281-

293-5337 

Company

Name/No: 

ConocoPhillips, 

00056 

Lease

Number(s): 32678, 32688, , , 

Area-Block:

Walker Ridge WR, 

416: , 460: , : , : , 

Surface

Locations: 3 

Payment Information

Payment Amount: $10,326.00

Transaction Date 

and Time:

07/17/2012 

18:33 EDT

Pay.gov - Online Payment Page 1 of 1

https://www.pay.gov/paygov/payments/authorizePlasticCardPayment.html 7/17/2012
SECTION B 

GENERAL INFORMATION 

(A) APPLICATIONS AND PERMITS 

Listed in the table below are additional permits/applications to be filed before operations can 

commence under this EP: 

Application/Permit Issuing Agency Status 

Applications for Permit to Drill BSEE To be submitted 

(B) DRILLING FLUIDS 

Type of Drilling Fluid Estimated Volume of Drilling Fluid to be 

Used per Well 

Water-based – 

Barite, Sodium Chloride Brine, Salt, 

Xantham Gum, Poly Plus, Lime, Poly Pac 

UL, Caustic Soda, Defoam X, 

Greencide 25g 

80,000 bbls water based mud (including 

dilution) 

Oil-based (diesel, minerals, oil) 0 bbls 

Synthetic-based (internal olefin, ester) 

Barite, Synthetic B, Suremul, Surewet, 

Rheflat, Rhethik, Lime, Calcium Chloride 

15,000 bbls synthetic-based mud (including 

dilution) 

(C) NEW OR UNUSUAL TECHNOLOGY 

No new or unusual technology is proposed for these operations. 

(D) BONDING STATEMENT 

The bond requirements for the activities and facilities proposed in this EP are satisfied by a 

$3,000,000.00 area-wide development bond, furnished and maintained according to 30 CFR 256, 

subpart I; NTL No. 2000-G16, "Guidelines for General Lease Surety Bonds;" 

(E) OIL SPILL FINANCIAL RESPONSIBILITY (OSFR) 

ConocoPhillips Company, BOEM Company Number 00056, will demonstrate oil spill financial 

responsibility for the facilities proposed in this EP according to 30 CFR Part 553; and NTL No. 

2008-N05, "Guidelines for Oil Spill Financial Responsibility for Covered Facilities". 

(F) DEEPWATER WELL CONTROL STATEMENT 

ConocoPhillips Company, BOEM Company Number 00056, will have the financial capability to 

drill a relief well and conduct other emergency well control operations. 

(G) BLOWOUT SCENARIO 

• Estimated Initial Flow Rate (bbls/day): Well Location A - 75,043 bbls/day 

• Maximum duration of potential blowout (days): 76 days 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page B-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
• Total Volume (bbls) (flow rate x duration): Based on the initial flow rate and the expected 

time to drill a relief well, the total discharge would be 5,703,268 bbls (initial flow rate x 

duration). However, incorporating the expected decline in flow rate over the time it takes to 

drill a relief well, the total discharge would be 3,956,000 bbls. 

• Discussion of potential for well to bridge over (include backup to support your assumption): 

The Thorn well worst case discharge estimate (WCD) has been based on a no bridge over 

assumption. Therefore the WCD volume is the likely rate and volume for a catastrophic failure 

without any restriction in the wellbore. Any bridging would restrict the assumed WCD flow 

rate and could, in the extreme case, curtail flow all together. 

• Discussion of likelihood for Surface intervention to stop blowout; As the Thorn well is 

planned to be a subsea well, minimal surface well control equipment will be in place to 

intervene should the primary subsea well control equipment fail. Neither the riser nor the 

diverter system beneath the rig floor is designed to shut in a flowing well. All intervention 

activities will most likely take place subsea and will involve the use of equipment provide by 

an industry consortium such as Marine Well Containment Company, of which ConocoPhillips 

is a member. 

Relief Well 

• Rig type capable of drilling relief well at water depth and to TD: The relief well would be 

drilled by a 5th or 6th generation drillship such as the Transocean Discoverer Inspiration (DIN) 

or the Discoverer Clear Leader (DCL) 

• Rig package constraints (if none, make statement to that effect): Both of the planned MODU’s 

have the ability to drill in the water depths expected for the planned well and have hook load 

capacities to drill a relief well. 

• Time to acquire rig and move onsite (days): It is estimated the time to notify the current 

operator of the DIN or DCL, suspend operations (TA), pull riser and transit to the Thorn 

location would be 16 days. 

• Drilling time (days): From rig arrival on location until the blown out well is intersected and 

killed, it is anticipated a total of 60 days would be required. 

• Statement whether possibility of using nearby platform was considered: No production 

platforms exist in the area and could not be used to drill a relief well. 

Other 

• Measures to reduce the likelihood of a blowout: Normal operational procedures followed in 

the industry will be practiced such as periodic flow checks, surge/swab monitoring and pit 

monitoring for increase levels which would indicate an influx from the formation into the 

wellbore (kick). The likelihood of a blowout is related to the number of “kicks” experienced 

with the goal to minimize the number of kicks taken in the drilling of the well. Mud weights 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page B-2 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
ConocoPhillips Company August, 2012 

Initial Exploration Plan Page B-3 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

will be employed to maintain sufficient hydrostatic pressure on the open formations to 

minimize the potential for kicks to occur. 

• Measures to enhance ability to conduct effective and early intervention in event of a blowout: 

ConocoPhillips is a member of the Marine Well Containment Company (MWCC), and 

industry consortium developed to aid its members in the unlikely event of a major subsea 

blowout. Membership in this consortium allows ConocoPhillips to access field proven 

equipment which is designed to be installed on a blowout well. ConocoPhillips will have in 

place prior to drilling commencement a “Covered Well Addendum” certificate from MWCC 

stating MWCC has reviewed the drilling plan and agreeing ConocoPhillips has access to the 

appropriate equipment to cap a blown out subsea well. 

• Arrangements for drilling relief wells: ConocoPhillips has a Mutual Aid Agreement with the 

current operators of the two MODU’s which could be used to drill a relief well – depending on 

which vessel can reach the Thorn location first. Required back up equipment such as subsea 

wellheads will have been either procured or identified from another operator. Most if not all

required tangibles for an emergency well are readily available in the GOM. 

• Any other measures: No 

Please see Attachment B-1 for additional NTL-2010-N06 calculations and data. 
SECTION C 

GEOLOGICAL AND GEOPHYSICAL INFORMATION 

(A) GEOLOGICAL DESCRIPTION

Proprietary Copy Only 

(B) STRUCTURE CONTOUR MAPS 

Current structure contour maps drawn on the top of each prospective hydrocarbon sand, showing 

the entire lease block, the location of each of the proposed wells, and the locations of geological 

cross-sections are included as Attachment C-1. (Proprietary Copy Only)

(C) INTERPRETED 3-D SEISMIC LINE(S) 

Attached to the Proprietary Information ConocoPhillips of this plan as Attachment C-2 are 

interpreted 3-D seismic lines. These lines are depth migrated, annotated with depth scale, and 

are within 500 feet of the surface locations of the proposed wells. (Proprietary Copy Only) 

(D) GEOLOGICAL STRUCTURE CROSS-SECTIONS

An interpreted geological structure cross-section showing the location and depth of each 

proposed well and at least one key horizon and the objective sands labeled using standard 

biostratigrahic terms are included as Attachment C-3. (Proprietary Copy Only) 

(E) SHALLOW HAZARDS REPORT 

A shallow hazards survey was conducted by Gardline Surveys, Inc. over Walker Ridge Blocks 

416, 417, 460 and 461 is being submitted under separate cover. 

 (F) SHALLOW HAZARDS ASSESSMENT 

Shallow hazards assessments prepared by Gardline Surveys, Inc. for Walker Ridge Blocks 416 

and 460 are included as Attachment C-4.

(G) HIGH-RESOLUTION SEISMIC LINES 

An annotated seafloor rendering map (Map 1 of 4) prepared by Fugro Geoservices, Inc. is 

included in Section E as Attachment E-1.

 

(H) STRATIGRAPHIC COLUMN

A generalized biostratigraphic/lithostratigraphic column depicting each well from the seafloor to 

total depth, with each objective horizon labeled, is included as Attachment C-5. (Proprietary 

Copy Only)

(I) TIME VS DEPTH TABLES

Proprietary Copy Only

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page C-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION D 

HYDROGEN SULFIDE INFORMATION 

(A) CONCENTRATION 

ConocoPhillips does not anticipate encountering any H2S during the proposed operations. 

(B) CLASSIFICATION 

Proprietary Data 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page D-1 

 Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION E 

BIOLOGICAL, PHYSICAL AND SOCIOECONOMIC INFORMATION 

(A) CHEMOSYNTHETIC COMMUNITIES REPORT 

The seafloor disturbing activities proposed in this plan are in water depths greater than 300 

meters (984’). Fugro Geoservices, Inc. was contracted to provide an assessment of the shallow 

conditions at the three proposed surface locations. The purpose of the assessment was to address 

seafloor conditions that may impact exploratory drilling operations within 2,000 feet of the 

proposed wellsites. ConocoPhillips will avoid all high-density deepwater benthic communities 

by 2,000 feet from each proposed mud and cuttings discharge location and 250 feet from the 

location of all other seafloor disturbances. 

Map 

Map 1 of 4 prepared by Fugro Geoservices, Inc. entitled "Archaeological, Bathymetry and 

Seafloor Features Map" is included as Attachment E-1. Using 3-D seismic data, the map depicts 

bathymetry, seafloor and shallow geological features, surface locations of the proposed wells, 

and a radius circle of 2,000 feet around each location. 

Analysis 

All seafloor features and areas located within 2,000 feet of each proposed muds and cuttings 

discharge location have been evaluated for high-density chemosynthetic communities. The 

proposed wells will be drilled with a drillship, thus, there are no associated anchors, anchor 

chains or wire ropes. 

Using 3-D seismic information, all seafloor features and areas that could be disturbed by the 

activities proposed in this plan have been identified. The likelihood of these proposed activities 

disturbing these seafloor and shallow geologic features is discussed below: 

Walker Ridge Block 416 Well Location D and Walker Ridge Block 460 Well Locations A and B 

do not contain features or areas that could support high-density chemosynthetic or deepwater 

benthic communities within 2000 feet of any proposed muds and cuttings discharge location or 

within 250 feet from the location of other seafloor disturbances. 

(B) TOPOGRAPHIC FEATURES MAP 

Activities proposed in this EP do not fall within 305 meters (1000 feet) of a topographic “no 

activity zone”. Therefore, no map is required per NTL No. 2008-G04. 

(C) TOPOGRAPHIC FEATURES STATEMENT (SHUNTING) 

All activities proposed under this EP will be conducted outside all Topographic Feature 

Protective Zones, therefore shunting of drill cuttings and drilling fluids is not required. 

(D) LIVE BOTTOMS (PINNACLE TREND) MAP 

Walker Ridge Blocks 416 and 460 are not located within 61 meters (200 feet) of any live-bottom 

(pinnacle trend) features. Therefore, no map is required per NTL No. 2008-G04. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page E-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
(E) LIVE BOTTOMS (LOW RELIEF) MAP 

Walker Ridge Blocks 416 and 460 are not located within 30 meters (100 feet) of any live-bottom 

(low-relief) features. Therefore, no map is required per NTL No. 2008-G04. 

(F) POTENTIALLY SENSITIVE BIOLOGICAL FEATURES 

Walker Ridge Blocks 416 and 460 are not located within 30 meters (100 feet) of potentially 

sensitive biological features. Therefore, no map is required per NTL No. 2008-G04. 

(G) REMOTELY OPERATED VEHICLE (ROV) SURVEYS 

BOEM has determined sufficient data has been gathered in Grid Area 11; therefore, ROV 

surveys will not be conducted prior to or after drilling operations for the purpose of biological 

and physical observations. 

(H)THREATENED AND ENDANGERED SPECIES, CRITICAL HABITAT, AND MARINE 

MAMMAL 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, Title 30 CFR 550.221, Subpart B, and further outlined in 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 proposed 

activities under this plan. 

There are five (5) species of sea turtles that may be found in the Gulf of Mexico (see table 

below). NOAA fisheries currently list all five of these turtles as endangered (E) or threatened 

(T). 

Species Scientific Name Status 

Potential Presence 

Critical Habitat Designated 

in the Gulf of Mexico Lease Area Coastal 

Sea Turtles 

Loggerhead carettsa caretta T x x None 

Green Chelonia mydas T,E x x None

Leatherback Dermochelys coriacea E x x None

Hawksbill Eretmochelys imbricata E x x None

Kemp’s Ridley Lepidochelys kempli E x x None

In addition, there are 28 species of marine mammals that may be found in the Gulf of Mexico. 

The table provided below identifies the seven (7) species of marine mammals that are listed as 

endangered or threatened. 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 during operations. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page E-2 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
ConocoPhillips Company August, 2012 

Initial Exploration Plan Page E-3 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

Species Scientific Name Status 

Potential Presence 

Critical Habitat 

Designated in the 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 masculus E X -- None

Fin whale Balaenoptera physalus E X -- None

Humpback whale Megaptera novaeangliae E X -- None

North Atlantic right whale Eubalaena glacialis E X -- None 

Sei whale Balaenopiera borealis E X -- None 

(I) ARCHAEOLOGICAL REPORT 

An archaeological report, entitled “Archaeological Assessment Blocks 416, 417, 460 and 461 

Walker Ridge Area Gulf of Mexico" prepared by Fugro Geoservices, Inc. is being submitted 

under separate cover. Per Fugro, "It is possible that historic shipwreck materials may not be 

detected by the geophysical instruments or may be obscured by modern debris. If wooden 

planking or other cultural materials that could represent shipwreck remains are encountered, the 

BOEM/BSEE archaeologists must be contacted immediately to provide an assessment of these 

artifacts, and all operations must cease within 1,000 feet of the exposed object." ConocoPhillips 

will comply with this requirement as necessary. 

(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 No. 2008-G04 is not applicable to this EP. 
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461

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JOB NO.: 24125002

POSITIONING BY: STARFIX

INTERPRETATION BY: M. SAMSON

DATE: JUNE 26, 2012

DWG NO.: 24125002.dwg

REVISION NO.: 0

DRAFTED BY: C. NOEL

MAP 1 OF 4

SURVEY DATES: APRIL 8 - 12, 2012

SURVEY VESSEL: FUGRO ENTERPRISE

200 DULLES DRIVE - LAFAYETTE, LOUISIANA 70506 - (337) 237-2636

Fugro GeoServices, Inc.

3,000 4,000

FEET

0 1,000 2,000

SCALE = 1:12,000

5,000

GEODETIC DATUM: NAD27

PROJECTION: UTM GRID UNITS: US SURVEY FEET

ZONE: U.T.M. 15 (NORTH)

 *** IMPORTANT - PLEASE NOTE ***

ANY COMMUNICATION AND/OR POWER CABLES THAT MAY BE PRESENT

IN THE AREA CANNOT BE LOCATED BY INSTRUMENTS UTILIZED DURING

THIS SURVEY. INQUIRIES SHOULD BE MADE TO INTERESTED PARTIES AS TO

THE PRESENCE OF SUCH OBSTRUCTIONS.

SHOT POINT & SHOT POINT No.

PROJECT

LOCATION

APPLIED ACOUSTIC VELOCITY = HARMONIC MEAN

ZERO DATUM = SEA LEVEL

CONTOUR INTERVAL = 10 FOOT

l l l l l

HACHURES ON DOWNTHROWN SIDE

NORMAL FAULT BURIED 1'-10' FEET BELOW SEAFLOOR,

(MINIMUM AVOIDANCE BOUNDARY WHERE APPLICABLE)

SIDE SCAN SONAR CONTACT WITH REFERENCE NUMBER

2

10'

l l l l l

HACHURES ON DOWNTHROWN SIDE

FAULT SCARP WITH SEAFLOOR OFFSET IN FEET,

1

1

1

NUMBER X COORDINATE Y COORDINATE

NUMBER X COORDINATE Y COORDINATE NUMBER X COORDINATE Y COORDINATE NUMBER X COORDINATE Y COORDINATE

CHECKED BY: B. DUVAL

ARCHAEOLOGICAL, BATHYMETY,

 & SEAFLOOR FEATURES MAP

BLOCKS 416, 417, 460, & 461

WALKER RIDGE AREA

HIGH PROBABILITY CHEMOSYNTHETICS WITH REFERENCE NUMBER

MEDIUM PROBABILITY CHEMOSYNTHETICS REFERENCE NUMBER

LOW PROBABILITY CHEMOSYNTHETICS REFERENCE NUMBER

AREA WITH MOUND-LIKE FEATURES WITH AMBIENT HEIGHT IN FEET
SECTION F 

WASTES AND DISCHARGES INFORMATION 

(A) PROJECTED GENERATED WASTES AND OCEAN DISCHARGES 

The table provided as Attachment F-1 summarizes information on the projected solid and liquid 

wastes likely to be generated by the activities proposed in this EP, and those wastes that will be 

discharged to the GOM. 

No wastes will be treated, stored or disposed of downhole at the offshore facility (NTL No. 

2009-G35). 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page F-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
(M POB 200 di 

A

 GENERATED WASTES 

Projected generated waste Projected ocean disch

Type of Waste Composition Pro Amounjected t per well Discharge rate Discharge M

Will drilling occur ? If yes, list muds and cuttings

Water-based drilling fluid Seawater and freshwater G Lignite, Barite el, NaCl, 80,000 bbls 1200 bbl/hr Max Rate Dis or charge over

at seafloor 

Cuttings wetted with water-based fluid

Cuttings generated while usbased drilling fluid

ing water- 4000 bbls 1200 bbl/hr Max Rate Dis or charge over

at seafloor 

Cuttings wetted with synthetic-based fluid

Cuttings generated while ussynthetic-based drilling fluid

ing 6000 bbls 500 bbls / day Dis or charge over

at seafloor 

Will humans be there? If yes, expect conventional waste

Domestic waste Gray water 900,000 gallons 6,000 gal/day (Max POB 200 Re andmove floatin

discharge 

Sanitary waste y Treated sanitary waste y 600,00 g 0 allons 4,000 gal/day (Max POB 200 Ch ax s dicharge lorinate and over

charge over

Is there a deck? If yes, there will be Deck Drainage

Deck Drainage Rainwater and rig washings 11,600 bbls 100 bbls/day Tre andat for oil and 

discharge 

Will you conduct well treatment, completion, or workover? 

Well treatment fluids NA NA NA N Non-pollutant completions fluids

Salt solutions, weighted brinpolymers and various additiv

es, 

es 8,000 bbls 200 bbl/hr Discharge over

Workover fluids NA NA NA NA 

Miscellaneous discharges. If yes, only fill in those associated with your activity. 

Desalinization unit discharge Rejected water from watermaker unit 23,200 bbl 200 bbls/day Discharge over

Blowout preventer fluid Blend (3% Stack Magic & po water) table 335 bbl 20bbl/week Dis or charge over

at seafloor 
A

Ballast water Uncontaminated seawater u maintain proper draft. sed to As needed As needed Discharge over

Bilge water Uncontaminated seawater 685 bbl As needed Discharge over

Excess cement at seafloor Cement slurry 1000 bbl 500 bbl/day Dis or charge over

at seafloor 

Fire water Seawater with no addition of chemicals As needed 140,000bbl/dayDischarge over

Cooling water Seawater with no addition of chemicals 16,240,000 bbl 140,000bbl/dayDischarge over

Will you produce hydrocarbons? If yes fill in for produced water.

Produced water NA NA NA N 

Will you be covered by an individual or general NPDES permit ? NPDES
SECTION G 

AIR EMISSIONS INFORMATION 

(A) EMISSIONS WORKSHEETS AND SCREENING QUESTIONS 

 Screen Procedures for EP’s Yes No 

Is any calculated Complex Total (CT) Emission amount (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)? X 

Do your emission calculations include any emission reduction measures or modified 

emission factors? X 

Are your proposed exploration activities located east of 87.5° W longitude? X 

Do you expect to encounter H2S at concentrations greater than 20 parts per million (ppm)? X 

Do you propose to flare or vent natural gas for more than 48 continuous hours from any 

proposed well? X 

Do you propose to burn produced hydrocarbon liquids? X 

There are no existing facilities or activities co-located with the currently proposed activities; 

therefore, the Complex Total Emissions are the same as the Plan Emissions and are provided in 

the table below. 

Drillship 

Air Pollutant 

Plan 

Emission 

Amounts 

(tons) 

Calculated 

Exemption 

Amounts 

(tons) 

Calculated 

Complex Total 

Emission 

Amounts (tons) 

Carbon Monoxide (CO) 459.41 104747.34 459.41 

Particular Matter (PM) 61.25 5694.30 61.25 

Sulphur Dioxide (SO2) 281.01 5694.30 281.01 

Nitrogen Oxides (NOx) 2105.62 5694.30 2105.62 

Volatile Organic Compounds (VOC) 63.17 5694.30 63.17 

This information was calculated by: Judy Davidson 

 (281) 578-3388 

 Judy.Davidson@jccteam.com

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page G-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION H 

OIL SPILLS INFORMATION 

(A) OIL SPILL RESPONSE PLANNING 

All proposed activities and facilities in this EP will be covered by the Regional OSRP filed by 

ConocoPhillips Company, BOEM GOM Number 00056, in accordance with 30 CFR 254 and 

approved on September 17, 2009 and modifications to that plan submitted January, 2011 and 

October, 2011 (currently pending approval). 

(B) SPILL RESPONSE SITES 

Primary Response Equipment Location Preplanned Staging Location 

Ingleside, Texas Aransas Pass, Texas 

Galveston, Texas Port O’Connor, Texas 

Port Arthur, Texas Freeport, Texas 

Lake Charles, Louisiana Galveston, Texas 

Houma, Louisiana Sabine Pass, Texas 

Belle Chase, Louisiana Lake Charles, Louisiana 

Venice, Louisiana Cameron, Louisiana 

Baton Rouge, Louisiana Morgan City, Louisiana 

Leeville, Louisiana Houma, Louisiana 

Fort Jackson, Louisiana Fourchon, Louisiana 

Pascagoula, Mississippi Grand Isle, Louisiana 

Tampa, Florida Venice, Louisiana 

Fort Jackson, Louisiana 

Pascagoula, Mississippi 

 Theodore, Alabama 

(C) OSRO INFORMATION

Clean Gulf Associates (CGA) and Marine Spill Response Corporation (MSRC) are the primary 

equipment providers for ConocoPhillips in the Gulf of Mexico region and maintain a dedicated 

fleet of vessels and other spill response equipment permanently located at designated ports. CGA 

and MSRC have the ability to rapidly mobilize and deploy substantial spill response resources on 

a 24 hour, 7 days a week basis. MSRC and/or their Spill Team Area Responders (STARs) 

subcontractors will operate all CGA equipment. In addition ConocoPhillips has a contract with 

National Response Corporation (NRC) for additional equipment. NRC's Independent Contractor 

Network (ICN) will provide the closest available personnel and additional equipment as needed. 

ConocoPhillips’ Oil Spill Response Plan includes subsea well containment capability through 

their Sponsor Membership in the Marine Well Containment Company (MWCC) LLC. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page H-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
ConocoPhillips Company August, 2012 

Initial Exploration Plan Page H-2 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

(D) WORST-CASE SCENARIO COMPARISON 

Category Regional OSRP 

WCD 

EP 

WCD 

Type of Activity Drilling Drilling 

Facility Location (Area/Block) Garden Banks Block 783 Walker Ridge Block 460 

Facility Designation Magnolia TLP 

Well Well A 

Distance to Nearest Shoreline 

(miles) 149 miles 174 miles 

Volume 

 Storage tanks (total) 2,158 barrels NA 

 Flowlines on Facility 200 barrels NA 

 Uncontrolled blowout 228,313 barrels 75,043 barrels 

Total Volume 230,671 barrels 75,043 barrels 

Type of Oil(s) 

(crude, condensate, diesel) Crude Oil Crude Oil 

API Gravity 400 280

ConocoPhillips has determined that the worst-case scenario from the activities proposed in this 

EP does not supersede the worst-case scenario from Regional OSRP. Since ConocoPhillips has 

the capability to respond to the appropriate worst-case spill scenario included in its revised 

regional OSRP submitted on October 4, 2011, and since the worst-case scenario determined for 

this EP does not replace the appropriate worst-case scenario in our regional OSRP, we hereby 

certify that ConocoPhillips 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 

As a member of CGA, NRCC and MWCC, ConocoPhillips 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 the EP. 

By letter dated September 1, 2011 ConocoPhillips submitted an OSRP certification statement 

certifying ConocoPhillip's capability to respond to the worst case discharge and requesting 

approval to operate for a period not to exceed two years while the Regional OSRP is pending 

approval. This certification statement was accepted by the BOEM on September 8, 2011. Worst 

case discharge calculations for Garden Banks Block 783, identified as the Regional OSRP worst 

case discharge, were approved on March 29, 2012 in the DOCD (Control Number 7506) as 

additional information to the plan per NTL 2010-N06. 

A Spill Response Discussion is included as Attachment H-1.
ATTACHMENT H-1 

SPILL RESPONSE DISCUSSION 

For the purpose of NEPA and Coastal Zone Management Act analysis, the largest spill volume 

originating from the proposed activity would be a well blowout during drilling operations, 

estimated to be 75,043 barrels of crude oil with an API gravity of 28°. 

Land Segment and Resource Identification

Trajectories of a spill and the probability of it impacting a land segment have been projected 

utilizing information in the BSEE Oil Spill Risk Analysis Model (OSRAM) for the Central and 

Western Gulf of Mexico available on the BSEE website. The results are shown in Figure 1. The 

BSEE OSRAM identifies a 3% probability of impact to the shorelines of Cameron Parish, 

Louisiana within 30 days. Cameron Parish includes the east side of Sabine Lake, Sabine National 

Wildlife Refuge, Calcasieu Lake, Lacassine National Wildlife Refuge (inland) and Grand Lake. 

Cameron Parish also includes the area along the coastline from Sabine Pass to Big Constance 

Lake in Rockefeller Wildlife Refuge. This region is composed of open public beaches, 

marshlands and swamps. It serves as a habitat for numerous birds, finfish and other animals, 

including several rare, threatened and endangered species. 

Response

ConocoPhillips will make every effort to respond to the Worst Case Discharge (WCD) as 

effectively as practicable. A description of the response equipment under contract to contain and 

recover the WCD is shown in Figure 2.

Using the estimated chemical and physical characteristics of crude oil, an ADIOS weathering 

model was run on a similar product from the ADIOS oil database. The results indicate 11% or 

approximately 8,254 barrels of crude oil would be evaporated/dispersed within 24 hours, with 

approximately 66,789 barrels remaining. 

Spill Response WR 460 A Barrels of Oil 

WCD Volume 75,043 

Less 11% natural evaporation/dispersion 8,254 

Remaining volume 66,789 

Daily dispersant capability 7,540 

Oil addressed by in-situ burning 3,339 

Figure 2 outlines equipment, personnel, materials and support vessels as well as temporary 

storage equipment available to respond to a spill of approximately 66,789 barrels. The volume 

accounts for the amount remaining after evaporation/dispersion at 24 hours. The list estimates 

individual times needed for procurement, load out, travel time to the site and deployment. Figure 

2 also indicates how operations will be supported. 

The ConocoPhillips’s Oil Spill Response Plan includes alternative response technologies such as 

dispersants and in-situ burn. Strategies will be decided by Unified Command based on the size 
of the spill, weather and potential impacts. If aerial dispersants are utilized, 8 sorties (9,600 

gallons) from two of the DC-3 aircrafts and 4 sorties (8,000 gallons) from the Basler aircraft 

would provide a daily dispersant capability of 7,540 barrels. If the conditions are favorable for 

in-situ burning, the proper approvals have been obtained and the proper planning is in place, insitu burning of oil may be attempted. Using estimates based on the Deepwater Horizon spill of 

2010, up to 5% or approximately 3,339 barrels of the total daily WCD volume could be burned. 

Slick containment boom would be immediately called out and on-scene as soon as possible. 

Offshore response strategies may include attempting to skim utilizing Clean Gulf Associate's 

HOSS Barge, and nine Fast Response Units (FRU), along with Marine Spill Response 

Corporation's (MSRC) Deep Blue Responder, Gulf Coast Responder, Texas Responder, PSV – 

HOS Centerline, and PSV – HOS Strongline, with a total derated skimming capacity of 142,723 

barrels. Temporary storage associated with skimming equipment equals 38,952 barrels. If 

additional storage is needed, three 20,000 barrel storage barges and a 47,000 barrel storage barge 

may be mobilized and centrally located to provide temporary storage allowing the skimmers to 

stay in the area of operations as much as possible. Safety is first priority. Air monitoring will 

be accomplished and operations deemed safe prior to any containment/skimming attempts. 

If the spill went unabated, shoreline impact in Cameron Parish, Louisiana would depend upon 

existing environmental conditions. Shoreline protection would include the use of CGA’s near 

shore and shallow water skimmers with a totaled derated skimming capacity of 13,253 barrels. 

Temporary storage associated with skimming equipment equals 256 barrels. If additional storage 

is needed, a 23,000 barrel storage barge may be mobilized and centrally located to provide 

temporary storage allowing the skimmers to stay in the area of operations as much as possible. 

Onshore response may include the deployment of shoreline boom on beach areas, or protection 

and sorbent boom on vegetated areas. A Master Service Agreement with ES&H will ensure 

access to 40,000 feet of 18” shoreline protection boom. Figure 2 outlines individual times 

needed for procurement, load out, travel time to the site and deployment. Strategies would be 

based upon surveillance and real time trajectories that depict areas of potential impact given 

actual sea and weather conditions. The State of Louisiana Initial Oil Spill Response Plan for 

Cameron Parish and Unified Command would be consulted to ensure that environmental and 

special economic resources would be correctly identified and prioritized to ensure optimal 

protection. Shoreline protection strategies depict the protection response modes applicable for oil 

spill clean-up operations. The State of Louisiana Initial Oil Spill Response Plan provides detailed 

shoreline protection strategies for this area, and it describes necessary action to keep the oil spill 

from entering Louisiana’s coastal wetlands, based on the assumption that removal of the released 

oil will be much easier and less damaging to fragile coastal ecosystems if done in the open 

waters of the Gulf of Mexico. Supervisory personnel have the option to modify the deployment 

and operation of equipment allowing a more effective response to site-specific circumstances. 

ConocoPhillips’s contract Spill Management Team holds a copy of the State of Louisiana Initial 

Oil Spill Response Plan. 

Based on the anticipated WCD scenario, ConocoPhillips can be onsite with contracted oil spill 

recovery equipment with adequate response capacity to contain and recover surface 

hydrocarbons, and prevent land impact, to the maximum extent practicable, within an estimated 

45 hours (based on the equipment’s Effective Daily Recovery Capacity (EDRC)). 
Initial Response Considerations 

Actual actions taken during an oil spill response will be based on many factors which include but 

are not limited to: 

• Weather 

• Equipment and materials availability 

• Ocean currents and tides 

• Location of the spill 

• Product spilled 

• Amount spilled 

• Environmental risk assessments 

• Trajectory and product analysis 

• Well status, i.e., shut in or continual release 

ConocoPhillips will take action to provide a safe, aggressive response to contain and recover as 

much of the spilled oil as quickly as it is safe to do so. In an effort to protect the environment, 

response actions will be designed to provide an “in-depth” protection strategy meant to recover 

as much oil as possible as far from environmentally sensitive areas as possible. Safety will take 

precedence over all other considerations during these operations. 

Upon notification of a spill, the following actions will be taken: 

• Information will be confirmed 

• An assessment will be made and initial objectives set 

• Oil Spill Response Organizations (OSRO) and appropriate agencies will be notified 

• ICS 201, Initial Report Form will be completed 

• Initial Safety plan will be written and published 

• Unified Command will be established 

o Overall safety plan developed to reflect the operational situation and coordinated 

objectives 

o Areas of responsibility established for Source Control and each surface operational 

site 

o On-site command and control established 

Offshore Response Actions 

Equipment Deployment

Surveillance 

• Surveillance Aircraft will be deployed within two hours of Qualified Individual (QI) 

notification, or at first light

• Provide trained observer to provide on site status reports 

• Provide command and control platform at the site if needed 

• Continual surveillance of oil movement by remote sensing systems, aerial photography 

and visual confirmation 

• Continual monitoring of vessel assets using vessel monitoring systems 
Dispersant application assets 

• Put Airborne Support Inc. (ASI) on standby 

• With the Federal On-Scene Coordinator (FOSC), conduct analysis to determine 

appropriateness of dispersant application 

• Gain FOSC approval for use of dispersants on the surface 

• Deploy aircraft in accordance with a plan developed for the actual situation 

• Coordinate movement of dispersants, aircraft, and support equipment and personnel 

• Confirm dispersant availability for current and long range operations 

• Start ordering dispersant stocks required for expected operations 

Containment boom 

• Call out early and expedite deployment to be on scene as soon as possible 

• Ensure boom handling and mooring equipment is deployed with boom 

• Provide continuing reports to vessels to expedite their arrival at sites that will provide for 

their most effective containment 

• Use Vessels of Opportunity (VOO) to deploy and maintain boom 

Dedicated offshore skimming systems 

General 

• Deployed to the highest concentration of oil 

• Assets deployed at safe distance from aerial dispersant and in-situ burn operations 

CGA HOSS Barge 

• Use in areas with heaviest oil concentrations 

• Consider for use in areas of known debris (seaweed, and other floating materials) 

CGA FRUs 

• To the area of the thickest oil 

• Use as far off-shore as allowed 

• VOOs 140’ – 180’ in length 

• VOOs with minimum of 18’ x 38’ or 23’ x 50’ of optimum deck space 

MSRC Oil Spill Response Vessels (OSRV) 

• Use in areas with heaviest oil concentrations 

• Use as far off-shore as allowed 

MSRC Responders 

• Use in areas with heaviest oil concentrations 

• Consider for use in areas of known debris (seaweed, and other floating materials) 
Storage Vessels 

• Establish availability of CGA contracted assets 

• Early call out (to allow for tug boat acquisition and deployment speeds) 

• Phase mobilization to allow storage vessels to arrive at the same time as skimming 

systems 

• Position as closely as possible to skimming assets to minimize offloading time 

Vessels of Opportunity (VOO) 

• Use ConocoPhillips’s contracted resources as applicable 

• Industry vessels are usually best for deployment of Vessel of Opportunity Skimming 

Systems (VOSS) 

• Acquire additional resources as needed 

• Consider use of local assets, i.e. fishing and pleasure craft 

• Expect mission specific and safety training to be required 

• Plan with the US Coast Guard for vessel inspections 

In-situ Burn assets 

• Determine appropriateness of in-situ burn operation in coordination with the FOSC and 

affected State On-Scene Coordinator (SOSC) 

• Determine availability of fire boom and selected ignition systems 

• Start ordering fire boom stocks required for expected operations 

• Contact boom manufacturer to provide training if required 

• Determine assets to perform on water operation 

• Build operations into safety plan 

• Conduct operations in accordance with an approved plan 
Near Shore Response Actions 

Timing 

• Place near shore assets on standby and deploy in accordance with planning based on the 

actual situation, actual trajectories and oil budgets 

• VOO identification and training in advance of spill nearing shoreline if possible 

• Outfitting of VOOs for specific missions 

• Deployment of assets based on actual movement of oil 

Considerations 

• Water depth, vessel draft 

• Shoreline gradient 

• State of the oil 

• Use of VOOs 

• Distance of surf zone from shoreline 

Equipment Deployment 

Surveillance 

• Provide trained observer to direct skimming operations 

• Continual surveillance of oil movement by remote sensing systems, aerial photography 

and visual confirmation 

• Continual monitoring of vessel assets 

Dispersant Use 

• Generally will not be approved within 3 miles of shore or with less than 10 meters of 

water depth 

• Approval would be at Regional Response Team level (Region 6) 

Vessel Deployment 

Dedicated Near Shore skimming systems 

• Fast Response Vessels (FRV) 

• Egmopol and Marco Shallow Water Skimmer (SWS) 

• Operate with aerial spotter directing systems to observed oil slicks 

VOO 

• Use ConocoPhillips’s contracted resources as applicable 

• Industry vessels are usually best for deployment of Vessel of Opportunity Skimming 

Systems (VOSS) 

• Acquire additional resources as needed 

• Consider use of local assets, i.e. fishing and pleasure craft 

• Expect mission specific and safety training to be required 

• Plan with the US Coast Guard for vessel inspections 

• Operate with aerial spotter directing systems to oil patches 
Shoreline Protection Operations 

Response Planning Considerations 

• Environmental risk assessments (ERA) to determine priorities for area protection 

• Time to acquire personnel and equipment and their availability 

• Previous contingency planning contained in the appropriate Area Contingency Plan, and 

currently for Louisiana, The State of Louisiana Initial Oil Spill Response Plan, Deep 

Water Horizon, dated 2 May 2010 

Actions 

Placement of boom 

• Position boom in accordance with the ERA based on the actual situation or the 

appropriate ACP 

• Assess timing of booming operations to ensure it is where it needs to be at time of 

impact. Consider: 

o Trajectories 

o Weather forecast 

o Oil Impact forecast 

o Verified spill movement 

o Boom, manpower and vessel (shallow draft) availability 

o Near shore boom and support material, (stakes, anchors, line) 

Beach Preparation 

Considerations and Actions 

• Use of a 10 mile go/no go line to determine timing of beach cleaning 

• Shoreline Cleanup and Assessment Team Reports and recommendations 

• Determination of Archeological sites and gaining authority to enter 

• Monitoring of tide tables and weather to determine extent of high tides 

• Pre cleaning of beaches by moving waste above high tide lines to minimize waste 

• Staging of equipment and housing of response personnel as close to the job site as 

possible to maximize on-site work time 

• Boom tending, repair, replacement and security (use of local assets may be advantageous) 

• Constant awareness of weather and oil movement for resource redeployment as necessary 

• In-situ burn may be considered when marshes have been impacted 

• Passive clean up of marshes should be considered and appropriate stocks of sorbent boom 

and/or sweep obtained 

• Earthen berms and shoreline protection boom may be considered to protect sensitive 

inland areas 
Decanting Strategy 

Recovered oil and water mixtures will typically separate into distinct phases when left in a 

quiescent state. When separation occurs, the relatively clean water phase can be siphoned or 

decanted back to the recovery point with minimal, if any, impact. Decanting therefore increases 

the effective on-site oil storage capacity and equipment operating time. FOSC/SOSC approval 

will be requested prior to decanting operations. This practice is routinely used for oil spill 

recovery. 

CGA Equipment Limitations 

The capability for any spill response equipment, whether a dedicated or portable system, to 

operate in differing weather conditions will depend on the capabilities of the vessel on which the 

system is placed. Most importantly, however, the decision to operate will be based on the 

judgment of the Unified Command and/or the Captain of the vessel, who will ultimately have the 

final say in terminating operations. Skimming equipment listed below may have operational 

limits which exceed those safety thresholds. As was seen in the Deepwater Horizon (DWH) oil 

spill response, vessel skimming operations ceased when seas reached 5-6 feet and vessels were 

often recalled to port when those conditions were exceeded. Systems listed below are some of 

the most up-to-date systems available and were employed during the Deepwater Horizon spill. 

Boom 3 foot seas, 20 knot winds 

Dispersants Winds more than 25 knots 

Visibility less than 3 nautical miles 

Ceiling less than 1,000 feet. 

FRU 8 foot seas 

HOSS Barge/OSRB 8 foot seas 

Koseq Arms 8 foot seas 

OSRV 4 foot seas 
Environmental Conditions in the Gulf of Mexico

Louisiana is situated between the easterly and westerly wind belts, and therefore, experiences 

westerly winds during the winter and easterly winds in the summer. Average wind speed is 

generally 14-15 mph along the coast. Wave heights average 4 and 5 feet. However, during 

hurricane season, Louisiana has recorded wave heights ranging from 40 to 50 feet high and 

winds reaching speeds of 100 mph. Because much of southern Louisiana lies below sea level, 

flooding is prominent. 

Surface water temperature ranges between 70 and 80 ̊F during the summer months. During the 

winter, the average temperature will range from 50 and 60 ̊F. 

The Atlantic and Gulf of Mexico hurricane season is officially from 1 June to 30 November. 

97% of all tropical activity occurs within this window. The Atlantic basin shows a very peaked 

season from August through October, with 78% of the tropical storm days, 87% of the minor 

(Saffir-Simpson Scale categories 1 and 2) hurricane days, and 96% of the major (Saffir-Simpson 

categories 3, 4 and 5) hurricane days occurring then. Maximum activity is in early to mid 

September. Once in a few years there may be a hurricane occurring "out of season" - primarily in 

May or December. Globally, September is the most active month and May is the least active 

month. 
FIGURE 1 

TRAJECTORY BY LAND SEGMENT 

Trajectory of a spill and the probability of it impacting a land segment have been projected 

utilizing ConocoPhillips’s WCD and information in the BSEE Oil Spill Risk Analysis 

Model (OSRAM) for the Central and Western Gulf of Mexico available on the BSEE 

website using 30 day impact. The results are tabulated below. 

Area/Block OCS-G Launch 

Area 

Land Segment and/or 

Resource 

Conditional 

Probability (%) 

within 30 days 

Drill and complete 3 

wells 

WR 460 A 

174 miles from shore 

G32688 C047 Matagorda, TX 

Brazoria, TX 

Galveston, TX 

Jefferson, TX 

Cameron, LA 

Vermilion, LA 

Terrebonne, LA 

Plaquemines, LA 

1 

1 

2 

1 

3 

1 

1 

1
WCD Scenario– BASED ON WELL BLOWOUT DURING DRILLING OPERATIONS (174 miles from s

66,789 bbls of crude oil (Volume considering natural weathering) API Gravity 28° 

FIGURE 2 – Equipment Response Time to WR 460 A 

Dispersants/Surveillance 

Dispersant/Surveillance Dispersant Capacity (gal) Storage Capacity Persons Req. From Hrs to Procure Hrs to Loadout Travel 

site 

CGA 

Basler 67T 2000 NA 2 Houma 1 1 1.1 

ASI 

DC 3 1200 NA 2 Houma 1 1 1.4 DC 3 1200 NA 2 Houma 1 1 1.4 Aero Commander NA NA 2 Houma 1 1 1.1 

Offshore Response 

Offshore Equipment 

Pre-Determined Staging EDRC Storage Capacity VOO Persons Required From Hrs to Procure Hrs to Loadout Hrs to GOM T

S

CGA 

HOSS Barge 43000 4000 3 Tugs 8 Harvey 7 0 5 

Recovered Oil Storage 

Pre-Determined Staging EDRC Storage Capacity VOO Persons Required From Hrs to Procure Hrs to Loadout Hrs to GOM T

S

Enterprise Marine Services LLC (available through contract with CGA) 

CTCo 2604 NA 20000 1 Tug 6 Amelia 4 12 4 CTCo 2605 NA 20000 1 Tug 6 Amelia 4 12 4 CTCo 2606 NA 20000 1 Tug 6 Amelia 4 12 4 CTCo 5001 NA 47000 1 Tug 6 Amelia 4 12 4 
Offshore Equipment 

Pre-determined Staging EDRC Storage Capacity VOO Persons Required From Hrs to Procure Hrs to Loadout Hrs to GOM 

MSRC 

Deep Blue Responder LFF 100 Brush + OSRV 6,600’ 44” Sea Sentry II Boom 660’ 67” LAMOR 

18086 4000 NA 14 Fourchon 2 0 1 

PSV – HOS Centerline 1 Crucial Disk 88/30 1,320’ EFC (cont inflate) 

11122 10626 NA 14 Fourchon 12 12 1 

PSV – HOS Strongline 1 Crucial Disk 88/30 1,320’ EFC (cont inflate) 

11122 10626 NA 14 Fourchon 12 12 1 

Gulf Coast Responder Transrec 350 + OSRV 5,280’ 44” Sea Sentry II Boom 2,640’ 67” LAMOR 

10567 4000 NA 14 Lake Charles 2 0 1 

Texas Responder Transrec 350 + OSRV 4,620’ 44” Sea Sentry II Boom 3,300’ 67” LAMOR 

10567 4000 NA 14 Galveston 2 0 1 
Staging Area: Fourchon

Offshore Equipment 

Preferred Staging EDRC Storage Capacity VOO Persons Req. From Hrs to Procure Hrs to Loadout Travel to Staging T

CGA 

FRU (1) + 100 bbl Tank (1) 4251 100 1 Utility 6 Harvey 1 2 2.75 FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Morgan City 1 2 2.5 FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Galveston 1 2 7 FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Ingleside 1 2 9.5 FRU (1) + 100 bbl Tank (2) 4251 200 1 Utility 6 Lake Charles 1 2 4 FRU (2) + 100 bbl Tank (4) 8502 400 2 Utility 12 Venice 1 2 4 FRU (2) + 100 bbl Tank (4) 8502 400 2 Utility 12 Leeville 1 2 .5 

Offshore Equipment 

Preferred Staging EDRC Storage Capacity VOO Persons Req. From Hrs to Procure Hrs to Loadout Travel to Staging T

CGA 

42” Auto Boom (5000’) NA NA 10 Crew 20 Galveston 1 2 7 42” Auto Boom (10000’) NA NA 20 Crew 40 Harvey 1 2 2.75 42” Auto Boom (2500’) NA NA 6 Crew 12 Ingleside 1 2 9.5 42” Auto Boom (5000’) NA NA 10 Crew 20 Lake Charles 1 2 4 42” Auto Boom (2500’) NA NA 6 Crew 12 Pascagoula 1 2 4 1000’ Hydro-Fire Boom NA NA 8 Utility 40 Harvey 1 4 2.5 

MSRC 

44” Sea Sentry II Boom (2860’) NA NA 6 Crew 12 Ingleside 1 2 9.5 44” Sea Sentry II Boom (4290’) NA NA 10 Crew 20 Galveston 1 2 7 44” Sea Sentry II Boom (6679’) NA NA 10 Crew 20 Lake Charles 1 2 4 44” Sea Sentry II Boom (1980’) NA NA 6 Crew 12 Fort Jackson 1 2 3.75 44” Sea Sentry II Boom (3190’) NA NA 10 Crew 20 Pascagoula 1 2 4 2000’ Hydro-Fire Boom NA NA 16 Utility 80 Lake Charles 1 4 4 
Nearshore Response 

Nearshore Recovered Oil Storage 

Pre-Determined Staging EDRC Storage Capacity VOO Persons Required From Hrs to Procure Hrs to Loadout Hrs to GOM T

S

Enterprise Marine Services LLC (available through contract with CGA) 

CTCo 2607 NA 23000 1 Tug 6 Amelia 4 12 4 

Staging Area: Cameron 

Nearshore and Inland 

Skimmers With Staging EDRC Storage Capacity VOO Persons Req. From Hrs to Procure Hrs to Loadout Travel to Staging T

Dep

CGA 

SWS Egmopol 3000 100 NA 3 Galveston 1 2 3.5 SWS Egmopol 3000 100 NA 3 Houma 1 2 4 SWS Marco 3588 34 NA 3 Houma 1 2 4 SWS Marco 3588 20 NA 3 Lake Charles 1 2 1 Rope Mop 77 2 0 3 Belle Chasse 1 2 4.5 
Shoreline Protection 

Staging Area: Cameron 

Shoreline Protection 

Boom VOO Persons Req. Storage/Warehouse Location Hrs to Procure Hrs to Load Out Travel to Cameron Travel to Deployment 

ES&H (available through MSA) 

20,000’ 18” Shoreline Boom 8 Crew 20 New Iberia, LA .5 .5 2.5 2 20,000’ 18” Shoreline Boom 8 Crew 20 Belle Chasse, LA .5 .5 4.5 2 

Beach Boom EDRC Storage Capacity VOO Persons Req. From Hrs to Procure Hrs to Loadout Travel to Staging T

Dep

CGA 

Beach Boom (2000’) NA NA NA 6 Galveston 1 2 3.5 Beach Boom (1000’) NA NA NA 4 Ingleside 1 2 6 Beach Boom (2000’) NA NA NA 6 Pascagoula 1 2 5.5 

Wildlife Response EDRC Storage Capacity VOO Persons Req. From Hrs to Procure Hrs to Loadout Travel to Staging T

Dep

CGA 

Wildlife Support Trailer NA NA NA 2 Houma 1 2 4 Bird Scare Guns (24) NA NA NA 2 Belle Chasse 1 2 4.5 Bird Scare Guns (12) NA NA NA 2 Galveston 1 2 3.5 Bird Scare Guns (24) NA NA NA 2 Houma 1 2 4 Bird Scare Guns (12) NA NA NA 2 Ingleside 1 2 6 Bird Scare Guns (24) NA NA NA 2 Lake Charles 1 2 1 Bird Scare Guns (24) NA NA NA 2 Pascagoula 1 2 5.5 

Response Asset Total 

Offshore EDRC 142,723 Offshore Recovered Oil Storage 145,952 Nearshore / Shallow Water EDRC 13,253 Nearshore / Shallow Water Recovered Oil Storage 23,256 
SECTION I 

ENVIRONMENTAL MONITORING INFORMATION 

(A) MONITORING SYSTEMS 

ConocoPhillips has a number of safety systems and practices in place to minimize the occurrence and 

subsequent impact of accidental releases. The systems are designed to alert operators with alarms in 

the event of a release. 

ConocoPhillips employees, contractors, and subcontractors are responsible for maintaining a vigilant 

watch for oil spill discharges of any magnitude from ConocoPhillips facilities and operations. Any 

person who observes or becomes aware of an oil spill shall immediately report the incident to the 

person in charge of the facility. The Person in Charge must then immediately notify the “On Call” 

Qualified Individual/Incident Commander. 

Facility operators are trained to respond to the various system alarms in order to identify and control 

releases immediately. The routine responsibilities that ensure oil spills will be detected and mitigated 

as soon as possible by facility operation personnel may include, but are not limited to the following: 

• Daily visual monitoring of all discharge points to ensure no presence of oil on the water. 

• Routine walk-through and monitoring of equipment and vessel pressures, temperatures, levels, etc. 

to ensure proper operation of all equipment at the facility. 

• Immediate response to alarms and signals that may indicate a possible release of oil. 

• Identify and shut off the source as soon as possible, taking safety into account. 

• Notify the ConocoPhillips Person in Charge as soon as possible to mitigate spill event. 

Additional monitoring will be conducted during routine helicopter flights to the facility and by routine 

marine vessels traveling to and from the facility. As stated above, any spills or sheens observed by 

these routine activities will be reported to the facility Person in Charge. 

Eddy or Loop currents will be monitored as per NTL 2009-G02 via Horizon Marine Services. 

ConocoPhillips subscribes to Impact Weather Service which provides real-time weather conditions 

such as tropical depressions, storms and/or hurricanes entering the Gulf. 

(B) INCIDENTAL TAKES 

To mitigate against incidental takes of protected species, all activities will be conducted in accordance 

with the following Notices to Lessees: 

• NTL No. 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting” 

• BSEE NTL No. 2012-G01, “Marine Trash and Debris Awareness and Elimination” 

• NTL-No. 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures and 

 Protected Species Observer Program” 

Operations proposed in this plan will not use explosives or an air gun. An auxiliary notification will be 

filed in support of a borehole seismic survey (VSP). Trained observers and a ramp-up procedure will 

be used per NTL No. 2012-JOINT-G02. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page I-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
ConocoPhillips Company August, 2012 

Initial Exploration Plan Page I-2 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

(C) FLOWER GARDEN BANKS NATIONAL MARINE SANCTUARY 

Walker Ridge Blocks 416 and 460 are not located in the Flower Garden Banks National Marine 

Sanctuary; therefore, provisions for monitoring the impact of an oil spill are not required in this EP. 
SECTION J 

LEASE STIPULATIONS INFORMATION 

Exploration activities are subject to the following stipulation attached to Leases OCS-G 32678 and 

OCS-G 32688 (Walker Ridge Blocks 416 and 460). 

Marine Protected Species 

Lease Stipulation No. 8 is meant to reduce the potential taking of marine protected species. 

ConocoPhillips will operate in accordance with NTL 2012-JOINT-G01 to minimize the risk of vessel 

strikes to protected species, report observations of injured or dead protected species, and prevent the 

intentional and/or accidental introduction of debris into the marine environment.

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page J-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION K 

ENVIRONMENTAL MITIGATION MEASURES INFORMATION 

(A) INCIDENTAL TAKES

Mitigation measures and monitoring for incidental takes of protected species will be conducted in 

accordance with the following Notices to Lessees, as applicable, to avoid or minimize impacts to any 

of the species listed in the ESA as a result of the operations conducted herein: 

• NTL No. 2012-JOINT-G01, “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting” 

• BSEE NTL No. 2012-G01, “Marine Trash and Debris Awareness and Elimination” 

• NTL No. 2012-JOINT-G02, “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program” 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page K-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION L 

SUPPORT VESSELS* AND AIRCRAFT INFORMATION 

(A) GENERAL 

The most practical, direct route from the shorebase as permitted by weather and traffic conditions will 

be utilized. 

Type Maximum Fuel 

Tank Capacity 

Maximum 

Number in Area 

at Any Time 

Trip 

Frequency or 

Duration 

Supply Vessel (PSV) 200,000 gallons 2 2 Trips/Week 

Fast Supply Vessel (FSV) 25,000 gallons 1 3 Trips/Week 

Helicopter 760 gallons 1 10/Week 

(B) DIESEL OIL SUPPLY VESSELS 

Fuel for the drilling unit will be transported via a supply vessel as follows: 

Size of Fuel 

Supply Vessel 

Capacity of Fuel 

Supply Vessel 

Frequency of 

Fuel Transfers 

Route Fuel Supply 

Vessel Will Take 

240’ minimum 200,000 gallons Every 20 days Most direct route 

from Fourchon, LA 

*Please note the actual vessels have not yet been contracted. 

(C) SOLID AND LIQUID WASTE TRANSPORTATION 

Table 2, “Wastes You Will Transport and/or Dispose of Onshore” is included in this section as 

Attachment L-1. 

(D) VICINITY MAP 

Enclosed as Attachment L-2 is a vicinity map showing the location of the activities proposed herein 

relative to the shoreline with the distance of the proposed activities from the shoreline and the primary 

route(s) of the support vessels and aircraft that will be used when traveling between the onshore 

support facilities and the drilling unit. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page L-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
Solid and Liquid Wastes 

transportation 

Type of Waste Composition Transport Method Name/Location of Facility 

Will drilling occur ? If yes, fill in the muds and cuttings. 

Spent Synthetic-based drilling fluid or mud SBM drilling fluids with high water % Internal mud tanks on marine vessel MI-SWACO, Port Fourchon Facility 

Synthetic-based drilling fluid or mud Used synthetic based drilling fluids Internal mud tanks on marine vessel MI-SWACO, Port Fourchon Facility 

Oil-based drilling fluid or mud NA NA NA 

Cuttings wetted with Water-based fluid NA NA NA Cuttings wetted with Synthetic-based fluid NA NA NA Cuttings wetted with oil-based fluids NA NA NA 

Will you produce hydrocarbons? If yes fill in for produced sand

ATTACHMENT L-1

WASTES TRANSPORTED TO SHORE 

Projected generated waste Waste Dis

Will you produce hydrocarbons? If yes fill in for produced sand.

Produced sand NA NA NA Trash and debris (non-recyclable) Non-recyclable non- hazardous trash and debris Storage bins on supply boat Newpark, Port Fourchon 

Trash and debris (recyclable) Recyclable non-hazardous trash and debris Bags or storage bins on supply boat Newpark, Port Fourchon 

Used oil

Used oil, oil filters, rags, pads, empty drums, cooking oil

Vendor supplied DOT storage bins on supply vessel then trucked to vendor facility.

Newpark, Port Fourchon 

Tank wash water Clean supply vessel tanks Truck Newpark, Port Fourchon Chemical product wastes Paints, solvents, unused chemicals, etc. Vendor supplied DOT storage bins on supply vessel then trucked to vendor facility. Newpark, Port Fourchon 

Will you have additional wastes that are not permitted for discharge? If yes, fill in the appropriate rows. 
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uth Marsh Island

North

Fourchon

Cocodrie

Grand Isle

River Ridge

Green Canyon

Walker Ridge

Ship Shoal

Eugene Island

Lund

South Timbalier

Atwater Valley

Ewing Bank

Grand Isle

Eugene Island South Ship Shoal South

West Delta

South Timbalier South

South Pelto

Terrebonne Lafourche

Plaquemines

ConocoPhillips Vicinity Map

Walker Ridge Block 416/460

WR416

W

R

416: ~171 Mile

s to

S

h

ore

W

R

4

6

0: ~17

4

Mile

s to

S

h

ore

WR416: ~182.5

Miles

to

Fourchon, LA

WR460: ~185.5

Miles

to

Fourchon, LA

WR460
SECTION M 

ONSHORE SUPPORT FACILITIES INFORMATION 

(A) GENERAL 

Per NTL No. 2008-G04, the following table reflects the onshore facilities to be utilized to provide 

supplies and services support for the activities proposed in this Exploration Plan. 

The onshore support bases for water and air transportation will be located in existing terminals in 

Fourchon and Amelia, Louisiana. 

Name of Shorebase Location Existing/New/Modified 

Chouest Port (C-Port) Port Fourchon, LA Existing 

PHI Heliport Amelia, LA Existing 

MI SWACO Port Fourchon, LA Existing 

Newpark Port Fourchon, LA Existing 

(B) SUPPORT BASE CONSTRUCTION OR EXPANSION 

There will be no new construction of an onshore support base, nor will an existing support base be 

expanded as a result of the operations proposed in this Exploration Plan. 

(C) WASTE DISPOSAL 

Table 2, “Wastes You Will Transport and/or Dispose of Onshore” is included in Appendix L as 

Attachment L-1.

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page M-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
SECTION N 

COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION 

Relevant enforceable policies were considered in certifying consistency for Louisiana. A certificate of 

Coastal Zone Management Consistency for the state of Louisiana is enclosed as Attachment N-1. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page N-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 

SECTION O 

ENVIRONMENTAL IMPACT ANALYSIS (EIA) 

 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page O-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688) 
Environmental Impact Analysis

INITIAL EXPLORATION PLAN

for

Walker Ridge Block 416 (OCS-G 32678)

Walker Ridge Block 460 (OCS-G 32688)

Offshore Louisiana

August 2012

Prepared for:

Bruce Wilcoxon

HSE Lead – Gulf of Mexico Exploration

ConocoPhillips Company

600 North Dairy Ashford

Houston, Texas 77079-1175

Telephone: (281) 295-5337

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997

Telephone: (772) 219-3000
Walker Ridge Blocks 416 and 460 August 2012 

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

A.3 Air Pollutant Emissions...................................................................................................................5

A.4 Effluent Discharges.........................................................................................................................8

A.5 Water Intake...................................................................................................................................8

A.6 Onshore Waste Disposal.................................................................................................................8

A.7 Marine Debris................................................................................................................................. 8

A.8 Support Vessel and Helicopter Traffic ............................................................................................9

A.9 Accidents ........................................................................................................................................9

A.9.1 Types of Accidents Evaluated .............................................................................................9

A.9.2 Small Fuel Spill ....................................................................................................................9

A.9.3 Crude Oil Spill (Worst Case Discharge) .............................................................................11

A.9.4 Other Accidents Not Analyzed in Detail............................................................................14

B. Affected Environment...........................................................................................15

C. Impact Analysis.....................................................................................................17

C.1 Physical/Chemical Environment...................................................................................................17

C.1.1 Air Quality .........................................................................................................................17

C.1.2 Water Quality....................................................................................................................19

C.2 Seafloor Habitats and Biota..........................................................................................................22

C.2.1 Soft Bottom Benthic Communities...................................................................................22

C.2.2 High-Density Deepwater Benthic Communities...............................................................24

C.2.3 Designated Topographic Features....................................................................................26

C.2.4 Pinnacle Trend Area Live Bottoms....................................................................................26

C.2.5 Live Bottom/Low Relief.....................................................................................................27

C.3 Threatened, Endangered, and Protected Species and Critical Habitat........................................27

C.3.1 Sperm Whale (Endangered)..............................................................................................29

C.3.2 West Indian Manatee (Endangered).................................................................................32

C.3.3 Endangered Mysticete Whales.........................................................................................33

C.3.4 Non-Endangered Marine Mammals (Protected)..............................................................34

C.3.5 Sea Turtles (Endangered/Threatened) .............................................................................37

C.3.6 Piping Plover (Threatened)...............................................................................................40

C.3.7 Whooping Crane (Endangered) ........................................................................................42

C.3.8 Gulf Sturgeon (Threatened)..............................................................................................43

C.3.9 Beach Mice (Endangered)................................................................................................. 43

C.4 Coastal and Marine Birds..............................................................................................................44

C.4.1 Marine Birds......................................................................................................................44

C.4.2 Shorebirds and Coastal Nesting Birds...............................................................................47
Contents

(Continued)

Page

Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page iii

C.5 Fisheries Resources ......................................................................................................................49

C.5.1 Pelagic Communities and Ichthyoplankton ......................................................................49

C.5.2 Essential Fish Habitat........................................................................................................52

C.6 Archaeological Resources.............................................................................................................55

C.6.1 Shipwreck Sites.................................................................................................................55

C.6.2 Prehistoric Archaeological Sites........................................................................................56

C.7 Coastal Habitats and Protected Areas..........................................................................................56

C.8 Socioeconomic and Other Resources...........................................................................................59

C.8.1 Recreational and Commercial Fishing ..............................................................................59

C.8.2 Public Health and Safety ...................................................................................................61

C.8.3 Employment and Infrastructure .......................................................................................62

C.8.4 Recreation and Tourism....................................................................................................63

C.8.5 Land Use............................................................................................................................64

C.8.6 Other Marine Uses............................................................................................................65

C.9 Cumulative Impacts......................................................................................................................65

D. Environmental Hazards.........................................................................................66

D.1 Geologic Hazards..........................................................................................................................66

D.2 Severe Weather............................................................................................................................67

D.3 Currents and Waves .....................................................................................................................67

E. Alternatives ..........................................................................................................67

F. Mitigation Measures.............................................................................................67

G. Consultation .........................................................................................................67

H. Preparers..............................................................................................................68

I. References.............................................................................................................68
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page iv

List of Tables

Table Page

1 Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact 

Analysis (EIA) .........................................................................................................................3

2 Matrix of impact-producing factors and affected environmental resources........................6

3 Conditional probabilities of a spill in the lease area contacting shoreline segments 

(From: Ji et al., 2004 ............................................................................................................12

4 Benthic community data from stations near the lease area (Data from: Wei, 2006; 

Rowe and Kennicutt, 2009) ................................................................................................. 22

5 Federally listed endangered and threatened species potentially occurring in the 

lease area and along the northern Gulf Coast ....................................................................28

6 Wildlife refuges, wilderness areas, and State and National parks within the 

geographic range of the potential shoreline contacts within 30 days following an 

oil spill in the lease area ......................................................................................................58

List of Figures 

Figure Page

1 Vicinity map for the lease area..............................................................................................2

2 Bathymetric map of Walker Ridge (WR) Blocks 460 and 416 showing the surface 

locations of proposed wells................................................................................................. 16

3 Location of selected environmental features in relation to the lease area........................41
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page v 

Acronyms and Abbreviations

ADIOS2 Automated Data Inquiry for Oil Spills 2 

bbl barrel

BLPD barrels of liquid per day

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Management, 

Regulation and Enforcement

BOP blowout preventer

BOPD barrels of oil per day

BSEE Bureau of Safety and Environmental 

Enforcement

CH4 methane

CO carbon monoxide

CO2 carbon dioxide

CFR Code of Federal Regulations

CGA Clean Gulf Associates

COP ConocoPhillips Company

DP dynamically positioned

DPS distinct population segment

EA Environmental Assessment

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ERMA Environmental Response Management 

Application

ESA Endangered Species Act

FAD fish-attracting device

FR Federal Register

Gardline Gardline Surveys Inc.

GMFMC Gulf of Mexico Fishery Management 

Council

H2S hydrogen sulfide

HAPC Habitat Area of Particular Concern

EP Exploration Plan

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

MSRC Marine Spill Response Corporation

MWCC Marine Well Containment Company

NAAQS National Ambient Air Quality Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric 

Administration

NO2 nitrogen dioxide

NOx nitrogen oxides

NPDES National Pollutant Discharge Elimination 

System

NPS National Park Service

NRDA Natural Resource Damage Assessment

NTL Notice to Lessees and Operators

NWR National Wildlife Refuge

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

OSRA Oil Spill Risk Analysis

OSHA Occupational Safety and Health 

Administration

OSRP Oil Spill Response Plan

PAH polycyclic aromatic hydrocarbon

PM particulate matter

SBM synthetic-based mud

SOx sulfur oxides

SOPEP Shipboard Oil Pollution Emergency Plan

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

WCD worst case discharge

WR Walker Ridge
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 1 

Introduction

ConocoPhillips (COP) is submitting an Initial Exploration Plan (EP) to the Bureau of Ocean Energy 

Management (BOEM1

) for Walker Ridge (WR) Blocks 416 and 460. Under the Initial EP, COP 

plans to drill up to three wells in WR 460 and 416. Drilling is anticipated to begin in May 2013 

and is expected to require approximately 116 days per well.

The lease area is 171 miles (275 km) south-southwest of the nearest shoreline (Louisiana), 

183 miles (295 km) from the onshore support base at Port Fourchon, Louisiana, and 215 miles 

(347 km) from the helicopter support base at Amelia, Louisiana (Figure 1). Water depths in the 

lease area range from 2,108 to 2,193 m (6,915 to 7,195 ft). The drilling rig is yet to be 

determined but will be a dynamically positioned (DP) drillship. 

This Environmental Impact Analysis (EIA) is a project- and site-specific analysis of COP’s planned 

activities prepared in accordance with the requirements of the Outer Continental Shelf Lands 

Act (OCSLA), Federal regulations including 30 Code of Federal Regulations (CFR) 550.212(o) and 

550.227, and Notice to Lessees and Operators (NTL) 2008-G04. As specified in NTL 2008-G04, an 

EIA focuses on the impacts of a specific plan to the extent feasible. Potential impacts have been 

analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the 

Outer Continental Shelf (OCS) Oil and Gas Leasing Program (MMS, 2007a), in multi-lease-sale 

EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008), and in the 

Environmental Assessment (EA) for Gulf of Mexico deepwater operations and activities 

(MMS, 2000). In addition, the Final Supplemental EIS for Central Planning Area lease 

sales 216/222 updates environmental information in light of the Macondo (Deepwater Horizon) 

incident and addresses potential impacts of a catastrophic spill (BOEM, 2012). The analyses 

from these documents are incorporated by reference.

COP submitted a revised Gulf of Mexico Regional Oil Spill Response Plan (OSRP) on 

4 October 2011 and a Regional OSRP Certification Letter per 30 CFR 254.2(b) to BOEMRE on 

1 September 2011. The Certification Letter was accepted by BOEMRE on 8 September 2011. 

Worst case discharge (WCD) calculations for Garden Banks Block 783, identified as the Regional 

OSRP WCD, were approved on 29 March 2012 in the DOCD (Control Number N-7506) as 

additional information to the plan per NTL 2010-N06. The regional OSRP details COP’s plan for 

response to rapidly and effectively manage oil spills that may result from drilling and production 

operations. COP has designed its response program based on a regional capability of response 

to spills ranging from small operational spills to a WCD from a well blowout. COP’s spill 

response program meets the response planning requirements of the relevant coastal states and

applicable Federal oil spill planning regulations and also includes information regarding COP’s

regional oil spill organization and dedicated response assets, potential spill risks, and local 

environmental sensitivities. The regional 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. In addition to the OSRP, ConocoPhillips 

operations will be governed by the company’s Safety and Environmental Management System 

(SEMS), a comprehensive system designed to reduce or eliminate the probability of incidents 

leading to harm to the offshore environment.

 

1 On 1 October 2011, the Bureau of Ocean Energy Management, Regulation and Enforcement (BOEMRE), formerly the 

Minerals Management Service (MMS), was replaced by the BOEM and the Bureau of Safety and Environmental Enforcement 

(BSEE) as part of a major reorganization.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 2 

Figure 1. Vicinity map for the lease area.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 3 

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 BOEM, BSEE, and JOINT NTLs 

applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) applicable to this Environmental Impact 

Analysis (EIA). 

NTL Title Summary

2012-BSEE-G01 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.

2012-JOINT-G01

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 injured or dead protected species.

2011-JOINT-G01

Revisions to the List of OCS Blocks 

Requiring Archaeological Resource 

Surveys and Reports

Provides new additions to the list of Outer Continental Shelf 

(OCS) blocks that require archaeological surveys and reports

(augments NTL 2005-G07).

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 comply with all applicable regulations, 

including the increased safety measures regulations (75 FR 63346). 

Informs operators that BOEMRE will evaluate 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 by 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.

2009-G06 Military Warning and Water Test 

Areas

Provides contact links to command headquarters for 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 military command 

headquarters concerning electromagnetic emissions and the use of 

boats and aircraft within warning areas or water test areas.
Table 1. (Continued).

Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 4 

NTL Title Summary

2008-G04

Information Requirements for 

Exploration Plans and Development 

Operations Coordination 

Documents

Provides 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.

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.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 5 

A. Impact-Producing Factors

Table 2 is a matrix of impact-producing factors (IPFs) and potentially affected environmental 

resources adapted from Form BOEM-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 sections. 

• 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

• Accidents

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

The exploration wells will be drilled using a DP drillship. The drillship will be on site for an 

estimated 116 days per 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 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.

A.2 Physical Disturbance to the Seafloor

DP drillships disturb only a very small area of the seafloor around the wellbore where the 

bottom template and blowout preventer are located. Physical disturbance of the seafloor will 

be limited to the area where the wellbore penetrates the substrate, where the blowout 

preventer is placed, and where water-based drilling mud and cuttings will be discharged at the 

seafloor during the initial well intervals prior to setting the marine riser. Depending on the 

specific well configuration, this area is generally about 0.25 ha (0.62 ac) per well. 

A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in 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 fuel by 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 BOEM requirements demonstrates that the projected 

emissions are below exemption levels specified by 30 CFR 250.303. Therefore, emissions are

not expected to significantly affect the air quality of the onshore area for any of the criteria 

pollutants. No further analysis or control measures are required.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 6 

Table 2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (--) = no impact or negligible impact.

Environmental Resources

Impact-producing Factors

Drilling Rig 

Presence (incl. 

noise & 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) -- -- -- -- -- --

Live Bottom/Low-Relief -- --(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 -- X(6)

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

Coastal wildlife refuges and wilderness areas -- -- -- -- -- -- -- X -- 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.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 7 

Table 2 Footnotes and Applicability:

(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any 

anchors will be on the seafloor within the following:

(a) 4-mi zone of the Flower Garden Banks, or the 3-mi zone of Stetson Bank;

(b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) 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 a 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.

• Activities occur within the Central Gulf OCS, therefore the Live Bottom (Low-Relief) Stipulation is not 

applicable to the lease area.

(4) Activities on blocks designated by the BOEM 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.

• EP Section D contains COP’s request for classification as an area in which H2S is absent.

(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 the BOEM 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 blocks that 

have a high potential for historic shipwrecks and is well beyond the 60-m depth contour used by the 

BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. An 

archaeological assessment by Fugro (2012) did not detect any shipwreck remains or other archaeological 

resources in the lease area.

(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, 

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.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 8 

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 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 that allows their return to the surface is set. Excess cement 

slurry will also be released at the seafloor during casing installation for the riserless portion of 

the drilling operations. 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 at an 

approved facility. Cuttings wetted with SBMs will be discharged at the seafloor in accordance 

with the NPDES permit.

Other effluent discharges in accordance with the NPDES permit will include non-contact cooling 

water, blowout preventer fluid, treated sanitary and domestic wastes, deck drainage, 

desalination unit brine, and uncontaminated fresh water and seawater for ballast, bilge and 

firewater systems. 

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. All affected intakes will be in accordance with the design, 

monitoring, and recordkeeping requirements of the NPDES permit.

A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F. Approximately 2,276 lb of 

recyclable and non-recyclable trash and debris will be generated per day of operations, or a 

total of 264,000 lb per well. The trash will be transported in storage bins or disposal bags to 

Port Fourchon, where it will be picked up by municipal operators for final disposal in accordance 

with applicable regulations.

A.7 Marine Debris

COP will comply with all regulations relating to solid waste handling and disposal, including the 

International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V 

requirements and USEPA and U.S. Coast Guard (USCG) regulations, as well as those of the BSEE. 

For example, BSEE 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. USEPA and USCG 

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 
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accidental loss of solid waste. In addition to the regulations in 30 CFR 250, BSEE issued 

NTL 2012-BSEE-G01, 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

COP’s primary shorebase facility will be located in Port Fourchon, Louisiana. The primary 

helicopter base will be located in Amelia, Louisiana. No terminal expansion or construction is 

planned at the locations.

The project will be supported by one crew boat and two supply vessels. It is estimated that the 

crew boat will make three round-trips per week and each supply vessel will make two 

round-trips per week. On average, support vessels will make a total of seven round-trips per 

week. The boats typically will move to the project area via the most direct route from the 

shorebase.

A helicopter will make 10 round-trips per week 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) 

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:

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

• The 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 COP’s spill response plans. Impacts are analyzed in Section C. 

Three other types of accidents were analyzed in EISs by MMS (2007b) and BOEM (2012): 

chemical spills, vessel collisions, and loss of well control. These types of accidents are discussed 

briefly in Section A.9.4. 

A.9.2 Small Fuel Spill

Spill Size. According to the analyses in MMS (2007b) and BOEM (2012), 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 the spill size 

increases, the incident rate declines dramatically (MMS, 2007b; BOEMRE, 2011; BOEM 2012). 

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 
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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, 2003). 

The constituents of these oils are light to intermediate in molecular weight and can be readily 

degraded by aerobic microbial oxidation. Due to its light density, diesel 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 (National Research 

Council, 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; BOEM, 2012). 

For purposes of this EIA, the fate of a small diesel fuel spill was estimated using NOAA’s 

Automated Data Inquiry for Oil Spills 2 (ADIOS2) 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 the density, viscosity, and water content of the spilled product. 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 171 miles (275 km) from the nearest shoreline (Louisiana). Modeling results 

discussed below indicate that a spill in the lease area would have a 3% or less probability of 

reaching the coastal areas of Louisiana within 30 days after a spill. By that time, essentially 

100% of a small fuel spill would have been dispersed or evaporated by natural processes, 

without taking into account COP’s response measures. MMS (2007b) similarly 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

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 

. The drilling rig utilized for these operations will comply with all applicable 

regulations regarding pollution prevention and control. The rig will have a Shipboard Oil 

Pollution Emergency Plan (SOPEP), which is reviewed and approved annually by the American 

Bureau of Shipping. The SOPEP is provided to assist employees in dealing with an unexpected 

discharge of oil. Its primary purpose is to set in motion the necessary actions to stop or 

minimize the discharge of oil and to mitigate its effects. Effective planning ensures that the 

necessary actions are taken in a structured, logical, and timely manner.
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and would result only in short-term environmental consequences. EP Section H provides a 

detailed discussion of COP’s response to a spill.

A.9.3 Crude Oil Spill (Worst Case Discharge)

Spill Size

In accordance with requirements of NTL 2010-N06, COP has estimated an initial WCD flow rate 

of 75,043 barrels of oil per day (BOPD) for this EP. The estimated maximum total time to drill a 

relief well is 76 days. This estimate includes time to suspend current operations on an existing

well, mobilization of another rig, transport of the relief-drilling rig to the blowout location, and 

60 days to drill the relief well and perform kill operations. Based on the initial flow rate and the 

expected time to drill a relief well, the total discharge would be 5,703,268 bbl (initial flow rate x 

duration). However, incorporating the expected decline in flow rate over the time it takes to 

drill a relief well, the total discharge would be 3,956,000 bbl. The detailed analysis of this 

calculation can be found in EP Section B. 

. 

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for 

evaluating oil spill risk during exploratory drilling. Historically, blowouts are rare events and 

most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a deep 

drilling 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). Of 

151 well blowouts in the Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills, 

with a total combined volume of 1,000 bbl of crude oil and condensate released (MMS, 2000). 

Between 1964 and 1999, almost all offshore spills (94%) from drilling and production-related 

operations on the OCS were less than or equal to 1 bbl in size (Anderson and LaBelle, 2000). 

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. BOEM 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; BOEM, 2012). According 

to BOEMRE’s Interim Final Drilling Safety Rule (75 Federal Register (FR) 63365 dated 

10 October 2010) issued following the Macondo incident, the baseline risk of a catastrophic 

blowout is estimated to be about once every 26 years. 

Included in EP Section B are COP’s calculations and information as required by NTL 2010-N06, 

including 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. COP 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 

computer simulation of oil spill transport that uses realistic data for winds and currents to 

predict spill fate. The OSRA report by Ji et al. (2004) provides conditional contact probabilities 

for shoreline segments. The results for Launch Area 47 (where the lease area is located) are 

presented in Table 3. The model predicts no shoreline contacts within 10 days after a spill. 

After 30 days, four Texas counties and four Louisiana parishes may be contacted, ranging from 
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Matagorda County, Texas, to Plaquemines Parish, Louisiana. The greatest probability of 

shoreline contact after 30 days is 3% for Cameron Parish, Louisiana.

Table 3. Conditional probabilities of a spill in the lease area contacting shoreline segments 

(From: Ji et al., 2004). Values are conditional probabilities that a hypothetical spill in 

the lease area (represented by Oil Spill Risk Analysis Launch Area 47) could contact 

shoreline segments within 3, 10, or 30 days.

Shoreline 

Segment County or Parish, State Conditional Probability of Contacta (%)

3 Days 10 Days 30 Days

C08 Matagorda County, Texas -- -- 1

C09 Brazoria County, Texas -- -- 1 

C10 Galveston County, Texas -- -- 2 

C12 Jefferson County, Texas -- -- 1 

C13 Cameron Parish, Louisiana -- -- 3 

C14 Vermilion Parish, Louisiana -- -- 1

C17 Terrebonne Parish, Louisiana -- -- 1

C20 Plaquemines Parish, Louisiana -- -- 1 a Conditional probability refers to the probability of contact within the stated time period, assuming that a spill has 

occurred (-- indicates less than 0.5%).

The original OSRA modeling conducted by Ji et al. (2004) did not evaluate the fate of a spill over 

time periods longer than 30 days, nor did it predict the fate of a release that continues over a 

period of weeks or months, as in the Macondo 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 the BOEM/MMS to evaluate 

contact probabilities for spills greater than 1,000 bbl.

To provide supplemental information about spill scenarios not addressed in the 30-day OSRA,

a special OSRA run was conducted to simulate a spill that continues over 90 consecutive days, 

with each trajectory tracked for 120 days during four seasons for the recent Western and 

Central Gulf of Mexico Planning Area Supplemental EISs (BOEMRE, 2011; BOEM, 2012). The 

spatial resolution of this special OSRA run is limited, with five launch points to represent the 

entire northern Gulf of Mexico. The nearest launch point to the lease area is Launch Point #3, 

which is about 71 miles (114 km) to the northeast. For this launch point, potential shoreline 

contacts after 120 days range from Cameron County, Texas (at the Texas/Mexico border) to 

Dade County in southeastern Florida. Based on statewide contact probabilities after 120 days, 

Texas and Louisiana shorelines have the highest likelihood of contact during all four seasons, 

with Louisiana having higher probabilities in spring (60%) and Texas having higher probabilities 

during all other seasons (ranging from 41% to 78%). The modeling predicts only a 1% probability 

of a spill contacting Alabama and Mississippi shorelines, and only during spring. The modeling 

predicts that Florida shorelines could be contacted in any season, with statewide probabilities 

ranging from 1% to 4%. Based on the 120-day trajectories, counties, or parishes with greater 

than 10% contact probability during any season range from Matagorda County, Texas, to 

Plaquemines Parish, Louisiana – the same geographic range predicted using the 30-day OSRA as 

summarized in Table 3. 

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, 
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Environmental Impact Analysis for Initial Exploration Plan Page 13 

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 (National Research Council, 2003).

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

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

. COP submitted a revised Gulf of Mexico Regional OSRP to BOEMRE on 

4 October 2011. In addition, COP submitted a Regional OSRP Certification Letter per 

30 CFR 254.2 (b) to BOEMRE on 1 September 2011, which was accepted by BOEMRE on 

8 September 2011. The OSRP provides a detailed plan for COP to respond to rapidly and 

effectively manage oil spills that may result from drilling and production operations. The OSRP 

contains detailed information on “Quick Response” procedures including responsibilities of all 

COP and contract personnel to report any observed discharge from known or unknown sources;

• contact information for alerting the spill management team complete with names, phone 

numbers, and locations.

In the event of a WCD, COP has access to surface and subsea response/containment capabilities 

that could be implemented through various organizations under contract. Clean Gulf Associates 

(CGA) and Marine Spill Response Corporation (MSRC) are the primary equipment providers for 

COP in the Gulf of Mexico region. CGA and MSRC have the ability to rapidly mobilize and deploy 

substantial spill response resources on a 24-hour, 7-days-a-week basis. MSRC and/or their Spill 

Team Area Responders will operate all CGA equipment. COP also is contracted with National 

Response Corporation for additional equipment. The Independent Contractor Network of 

National Response Corporation will provide the closest available personnel and additional 

equipment as needed. 

COP’s OSRP includes subsea well containment capability through their Sponsor Membership in 

the Marine Well Containment Company (MWCC) LLC. In the event of an incident, MWCC can 

provide a 15,000-psi single ram capping stack and dispersant injection capability. MWCC can 

also install and operate the interim containment system, including subsea flowlines, manifold, 

and risers. The interim system is engineered for use 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.

COP also is contracted with the Marine Spill Response Corporation (MSRC) for additional spill 

response equipment. MSRC has a dedicated fleet for the Atlantic/Gulf of Mexico region and 

additional available equipment staged throughout the United States. The equipment MSRC 

stages throughout the Gulf of Mexico includes seven oil spill response vessels, two fast response 
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Environmental Impact Analysis for Initial Exploration Plan Page 14 

vessels, five oil spill response barges, five platform supply vessels, and 15 shallow-water barges. 

Various equipment is outfitted with x-band and infrared technology.

MSRC recently completed a large expansion of its resources and capability in the Gulf of Mexico, 

with particular focus on deepwater activities. The expansion is known as “Deep Blue.” 

Additional MSRC capabilities and a complete equipment listing are available on-line at:

http://www.msrc.org/. 

See EP Section H for a detailed description of COP’s site-specific response to the WCD for this 

plan.

A.9.4 Other Accidents Not Analyzed in Detail

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 along with a hydrogen sulfide (H2S) release 

are discussed briefly below. There are no other site-specific issues raised by well drilling 

proposed in this EP.

Chemical Spills

A study of environmental risks of chemical products used in OCS activities determined that only 

two chemicals could potentially affect the marine environment in the concentrations typically 

used: zinc bromide and ammonium chloride (Boehm et al., 2001). The project addressed by this 

EP does not anticipate the use of either zinc bromide or ammonium chloride. Most other 

chemicals are either nontoxic or used in small quantities. No significant impacts are expected 

from chemical spills.

. Chemicals are used in drilling operations to achieve technical goals in the 

drilling process, improve the efficiency and safety of drilling, and protect associated equipment. 

Chemicals used during exploration and drilling include surfactants, bentonite clays, olefins, 

inorganic salts, glycols, polymers, barite, and calcium carbonate. In addition to chemicals used 

in drilling fluids, the following chemicals are likely to be used on the rig: ethylene glycol 

(blowout prevention control fluid, used in closed cooling loops for crane and main engines and 

brake coolers), cement (used to cement casing in place), solvents (used in painting operations), 

hydraulic fluids (used in cranes and other hydraulic rig equipment), lubricating oil and grease 

(used in reciprocating and electrical equipment), and sodium hypochlorite (dilute, used as 

laundry bleach and disinfectant). Supplies are renewed on a regular basis by transfer in 

containers from supply boats (Boehm et al., 2001).

Vessel Collisions. BOEM 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 resulted in diesel spills, and in several collision incidents fires resulted from 

hydrocarbon releases. 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, although oil, natural 

gas, corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of 

vessel collisions. Human error accounts for approximately half of all reported vessel collisions 

from 2006 to 2009. As summarized in MMS (2007b) and BOEM (2012), vessel collisions 

occasionally occur during routine operations. Some of these collisions have caused spills of 

diesel fuel or chemicals. COP will comply with all USCG- and BOEM-mandated safety 
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Environmental Impact Analysis for Initial Exploration Plan Page 15 

requirements to minimize the potential for vessel collisions. Impacts are discussed further in 

recent lease sale EISs (MMS, 2007b; BOEMRE, 2011; and BOEM, 2012).

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 

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. COP 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. In accordance with Title 30 CFR 250.490(c), COP has requested that WR Blocks 416 

and 460 be classified by the BOEM as H2S absent. This determination was based on the 

evaluation of two offset wells (WR 372 Well 1 [OCS-G 18701] and WR 508 Well 1 

[OCS-G 17001]), which penetrated the stratigraphic section equivalent to the target interval 

proposed in this EP. Therefore, an H2S release is not analyzed further.

B. Affected Environment

The lease area is in the central Gulf of Mexico, 171 miles (275 km) from the nearest shoreline

(Louisiana), 183 miles (295 km) from the onshore support base at Port Fourchon, Louisiana, and 

215 miles (347 km) from the helicopter base at Amelia, Louisiana (Figure 1).

Figure 2 shows bathymetric maps of WR 416 and WR 460, including the proposed well surface 

locations. Based on the well clearance letters prepared by Gardline Surveys Inc. (Gardline, 

2012), the water depths of the proposed surface locations range from 2,108 to 2,193 m 

(6,915 to 7,195 ft). There is no evidence of significant seafloor or subsurface faulting, fluid 

expulsion features, or high-density deepwater benthic communities within a 610-m (2,000-ft) 

radius of the proposed well locations.

A detailed description of the regional affected environment is provided in recent lease sale EISs, 

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 (MMS, 2007b, 2008; BOEMRE, 2011; BOEM, 

2012). These regional descriptions remain valid and are incorporated by reference. General 

background information is presented below, and brief descriptions of each potentially affected 

resource, including site-specific and/or new information if available, are presented in Section C. 
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Environmental Impact Analysis for Initial Exploration Plan Page 16 

Figure 2. Bathymetric map of Walker Ridge (WR) Blocks 460 and 416 showing the surface locations of proposed wells. (Water depth is in feet.)
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 17 

The Macondo spill has resulted in environmental impacts to portions of the Gulf of Mexico. The 

lease area is located approximately 218 miles (351 km) west-southwest of the Macondo spill 

site. While the Macondo spill resulted in impacts to water quality in the area of the spill, based 

on an analysis of satellite imagery (Environmental Response Management Application [ERMA] 

Gulf Response, 2012), the surface slick did not extend over the lease area, therefore, existing 

water quality in the lease area was not likely to have been affected. 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). 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). Various 

monitoring efforts and environmental studies are in progress, but it is not currently possible to 

precisely estimate the long-term impacts the spill will have on offshore water quality (BOEMRE, 

2011; BOEM, 2012). Based on the information currently available and distance from the 

Macondo spill site, there is no reason to expect any change in water quality conditions in the 

lease area from those predicted prior to and since the Macondo spill in the recent lease sale EISs

(MMS, 2007b, 2008 and BOEMRE, 2011; BOEM, 2012). 

C. Impact Analysis

This section analyzes the potential direct and indirect impacts of routine activities and accidents. 

Impacts have been analyzed extensively in recent lease sale EISs for the Central and Western 

Gulf of Mexico Planning Areas (MMS, 2007b, 2008; BOEMRE, 2011; BOEM 2012) as well as the 

Environmental Assessment (EA) 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. Because of the distance from 

shore-based pollution sources and the lack of sources offshore, air quality in the lease area 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 March 2012, all Alabama, Florida, and Mississippi coastal counties adjacent to the Central 

and Western Planning Areas are in attainment of the National Ambient Air Quality Standards 

(NAAQS) for all criteria pollutants (USEPA, 2012). Two metropolitan areas in Texas are 

nonattainment areas for 8-h ozone (Dallas-Fort Worth and Houston-Brazoria); and El Paso 

County, Texas, is a nonattainment area for PM-10 (USEPA, 2012).

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.
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Environmental Impact Analysis for Initial Exploration Plan Page 18 

BOEM (2012) has reexamined the analysis for air quality presented in previous lease sale EISs 

(MMS, 2007b, 2008) based on additional information and in consideration of the Macondo oil 

spill event. No substantial new information was found that would alter the analysis of potential 

impacts on air quality. 

Potential IPFs for air quality would be routine air pollutant emissions, a small fuel spill, and a 

large oil spill (WCD).

Potential 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, 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.

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 prepared in 

accordance with BOEM requirements shows that the projected emissions are below exemption 

levels (EP Section G). 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. No 

further analysis or control measures are required and no significant onshore impacts are 

expected.

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).

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 Class I air quality 

area. The BOEM 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 227 miles (366 km) from the Breton 

Wilderness Area, and therefore significant impacts on the Class I area are not expected.
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Environmental Impact Analysis for Initial Exploration Plan Page 19 

Potential 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 recent lease sales (MMS, 2007b, 2008; BOEMRE, 2011; 

BOEM, 2012). The probability of a small spill would be minimized by COP’s preventative 

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

implementation of COP’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).

Potential 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 recent lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011; 

BOEM, 2012).

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. Real-time 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. However, in situ burning would occur only after authorization 

from the USEPA.

Due to the lease area location (171 miles [275 km]) from the nearest shoreline (Louisiana), most 

air quality impacts would occur in offshore waters with minimal chance to affect onshore air 

quality. Air quality monitoring following the Macondo spill provides an indication of the 

potential for air quality impacts from a large spill. The USEPA and the affected states conducted 

extensive air quality monitoring along the Gulf coast. The air quality monitoring indicated that 

the levels of ozone and particulates were at levels well below those that would cause short-term 

health problems and did not detect any pollutants at levels expected to cause long-term harm 

(BOEM, 2012). 

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 a recent lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of 

Mexico are relatively homogeneous with respect to temperature, salinity, and oxygen. 
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 20 

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 218 miles (351 km) from the Macondo spill site. Based 

on the general circulation pattern seen in the Gulf of Mexico and satellite imagery (ERMA Gulf 

Response, 2012), the surface slick from that discharge did not extend into this lease area during 

the spill and water quality within in the lease area was not affected. Water quality in deep, 

offshore waters of the Gulf of Mexico is 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 lease area from those predicted in the recent 

lease sale EISs (MMS 2007b, 2008; BOEMRE, 2011; BOEM, 2012). 

IPFs potentially affecting water quality are effluent discharges and two types of accidents – 

a small fuel spill and a large oil spill (WCD).

Potential 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 for water-based drilling muds and cuttings. 

SBMs will be collected on the rig and either reused by the vendor, or transported to 

Port Fourchon and onwards to an approved facility for recycling and/or disposal in an approved 

facility. Cuttings wetted with SBMs will be discharged at the seafloor in accordance with the 

NPDES permit. All NPDES permit limitations and requirements will be met. There will be no 

persistent impacts on water quality in the lease area (National Research Council, 1983; 

Neff, 1987; Neff et al., 2000).

Treated sanitary and domestic wastes, including those from support vessels, may have a slight 

transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit 

limitations and requirements and USCG regulations (as applicable) 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. Pollution prevention measures that will 

be used by COP to meet NPDES permit requirements include the installation of curbs, gutters, 

drip pans, and drains on deck areas to collect all contaminants and debris. Most deck drains and 

some of the joints at the edge of the rig floor will go overboard or into the moonpool, 

respectively. A dedicated drip pan will be installed under the rotary table to prevent ocean 

discharge from the drains. The pipe racks, mud pump room, sack store, and drill floor drains go 

to a holding tank, which is served by a dedicated oily water separator. The well test area, engine 

room, and other major machinery spaces drains all go to slops tanks, which are served by a large 

general-service, oily water separator. The containment devices are temporary and are not 

meant for permanent storage of waste. On the rare occasion that they contain wastes, they will 

be pumped, mopped, or cleaned within a short period of time. The chances of damage to a 

containment structure during such time as it contains wastes are exceedingly small. Based on 

adherence to COP’s pollution prevention measures, permit limits, and applicable regulations, 

little or no impact on water quality is anticipated.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 21 

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, 

resulting in little or no impact on water quality.

Potential 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; BOEMRE, 2011; BOEM, 2012). The 

probability of a small spill would be minimized by COP’s preventative measures during routine 

operations, including fuel transfer. In the unlikely event of a spill, implementation of COP’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). 

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 (National Research Council, 2003). The constituents of these oils are light to 

intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. 

Due to its light density, diesel 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 solid loads (National Research Council, 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).

Potential 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 recent lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011; 

BOEM, 2012). 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 Science Advisory Team Unified Area Command, 2010).
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 22 

Due to the lease area location (171 miles [275 km] from the nearest shoreline [Louisiana]), it is 

expected that most water quality impacts would occur in offshore waters. Depending on the 

spill trajectory and the effectiveness of spill response measures, coastal water quality could be 

affected. Based on the 30-day OSRA modeling predictions (Table 3), nearshore waters and 

embayments of Cameron Parish, Louisiana, are the coastal areas with the most potential for 

water quality to be affected. 

C.2 Seafloor Habitats and Biota

Water depths at the proposed well locations range from 2,108 to 2,193 m (6,915 to 7,195 ft). 

The seafloor at the proposed well locations appears to be smooth and featureless; at WR 460-A 

and WR 460-B it dips to the northeast at approximately 3.4o

, and at WR 416-D it dips to the 

southeast at <1.0o

 (Gardline, 2012). Because no hard bottom areas were detected by side-scan 

sonar during the site clearance survey, the seafloor is expected to consist mainly of soft bottom 

communities. The survey did not identify any features that could support high-density 

deepwater benthic communities within a 610-m (2,000-ft) radius of the three potential well 

locations. 

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. 

Table 4 summarizes data from nearby stations in water depth similar to the lease area. 

Sediments at these two stations were predominantly clay (55% to 60%) and silt (40% to 55%).

Table 4. Benthic community data from stations near the lease area (Data from: Wei, 2006; 

Rowe and Kennicutt, 2009). 

Station Water Depth

(m)

Abundance

Meiofauna

(individuals/m2) 

Macroinfauna

(individuals/m2) 

Megafauna

(individuals/ha)

NB5 2,065 117,263 706 1,600

B1 2,255 157,417 1,446 252

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal data from Wei (2006). 

Densities of meiofauna (animals passing through a 0.5-mm sieve but retained on a 0.062-mm 

sieve) in water depths representative of the lease area (2,108 to 2,193 m [6,915 to 7,195 ft]) 

typically are approximately 200,000 individuals/m2 (Rowe and Kennicutt, 2009). Nematodes, 

nauplii, and harpacticoid copepods were the three dominant meiofaunal groups, accounting for 

about 90% of total abundance.

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

both of which reflect the meager primary production in Gulf of Mexico surface waters 

(Wei, 2006). Densities decrease exponentially with water depth. Based on an equation 

presented by Wei (2006), macroinfaunal densities in the water depths of the lease area are 

expected to be about 1,339 to 1,426 individuals/m2

, or between the macroinfauna densities for 

the closest locations with similar water depths listed in Table 4. 
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Environmental Impact Analysis for Initial Exploration Plan Page 23 

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. The most abundant taxa present in this zone, with 

stations in water depths of 1,875 to 3,008 m (6,152 to 9,869 ft) were the polychaetes Levinsenia 

uncinata, Paraonella monilaris, and Tachyrtrypane sp., a bivalve Heterodonata sp. B and an 

isopod Macrostylis 256. Megafaunal densities from nearby stations NB5 and B1 were 1,600 and 

252 individuals/ha, respectively (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 also are 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/m2 in the top 15 cm of sediments (Rowe and Kennicutt, 2009).

IPFs potentially affecting soft bottom benthic communities are physical disturbances to the 

seafloor, 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 would float and dissipate on the sea surface.

Potential Impacts of Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships disturb the seafloor only 

around the wellbore where the bottom template and blowout preventer are located. 

Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac) per 

well. 

The areal extent of these impacts from a DP rig would be small compared to the lease area 

itself, and these type soft bottom communities are ubiquitous along the northern Gulf of Mexico 

continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Physical 

disturbance of the seafloor during this project will have no significant impact on soft bottom 

benthic communities in the region. 

Potential 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.

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily 

within several hundred meters of each 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 
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 24 

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 

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 a single exploratory 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.

Potential 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. The MMS (2007b) estimated 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).

Recent lease sale EISs (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). 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 (National Research 

Council, 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; 
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 25 

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

carbonates created by chemosynthetic communities.

The nearest known high-density deepwater benthic community is located approximately 

41 miles (65 km) north-northwest of the lease area in GC 852. Three localized fluid escape 

features with the potential to harbor sensitive sessile benthic communities were identified 

within the Gardline four-block survey area (WR 416, WR 417, WR 460, and WR 461); the nearest 

identified area is located in WR 416/WR 417, approximately 1.8 to 2.8 km (5,977 to 9,034 ft) 

from the well locations (Gardline, 2012). Based on the well clearance letters by Gardline (2012)

as summarized in EP Section C, there are no features or areas that could support significant 

deepwater benthic communities within a 610-m (2,000-ft) radius around the proposed wellsites. 

Therefore, the potential for high-density deepwater communities near the wellsites is 

considered low (Gardline, 2012).

A large oil spill (WCD) from a well blowout at the seafloor is the only IPF potentially affecting

high-density deepwater benthic communities. A small fuel spill would not affect benthic 

communities because the diesel fuel would float and dissipate on the sea surface. Because a 

DP drillship will be used, there will be no physical disturbance to the seafloor from anchoring 

during the drilling activities analyzed in this EIA. 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). 

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.

Potential 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 

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 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 deepwater column without substantial 

oxygen drawdown.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 26 

Potential impacts of oil on high-density deepwater benthic communities are discussed in 

MMS (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). 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 observed dead and dying corals with sloughing tissue and discoloration. Much of the soft 

coral observed in an area measuring about 15 by 40 m (50 by 130 ft) was covered by what 

appeared to be a brown flocculent material (BOEMRE, 2010) with signs of widespread stress, 

including varying degrees of tissue loss and excess mucous production (White et al., 2012). 

Researchers concluded, based on hopanoid petroleum biomarker analysis of the flocculent 

material, that it contained oil from the Macondo spill. The injured and dead corals were in an 

area where a subsea plume of oil had been documented during the spill in June, 2010; corals 

elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be 

experiencing higher mortality. The research team concluded that the observed coral injuries 

likely resulted from exposure to the subsurface oil plume (White et al., 2012).

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 Ship Shoal South 

101 miles (162 km) north of the lease area in Ewing Bank Block 945. 

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. 

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 area is in Main Pass Block 290, which lies 241 miles 

(387 km) northeast of the lease area.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 27 

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 Live Bottom/Low Relief

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 Block 573, approximately 277 miles (446 km) northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause 

impacts to 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.
Walker Ridge Blocks 416 and 460 August 2012 

Environmental Impact Analysis for Initial Exploration Plan Page 28 

Table 5. Federally listed endangered and threatened species potentially occurring 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

b X X None

Green turtle Chelonia mydas T, Ec 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 In September 2011, NMFS and USFWS listed nine distinct population segments (DPS) of loggerhead turtles under 

the Endangered Species Act. The Northwest Atlantic Ocean DPS was designated as threatened (76 FR 58868). c The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

As mandated by the ESA, BOEM consulted NMFS and the USFWS on possible and potential 

impacts from the proposed leasing in the Gulf of Mexico 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 Five-Year Leasing Plan for Western and 

Central Planning Areas 2007-2012 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 MMS’s determination that 

proposed actions of the current Five-Year Leasing Plan were not likely to adversely affect 

threatened/endangered species or designated critical habitat under USFWS jurisdiction. 

Following the Macondo spill, BOEM requested to reinitiate an ESA consultation with both NMFS 

and USFWS on 30 July 2010. At present, the NMFS and USFWS have placed the consultation 

process on hold because they feel the environmental baseline information needs to be updated 
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for the post-Macondo spill environment based on the results of the Natural Resource Damage 

Assessment (NRDA) process. The NRDA data have yet to be released, and the existing

consultation remains in effect (BOEM, 2012). The existing consultation recognizes that 

BOEM-required mitigations and other reasonable and prudent measures should reduce the 

likelihood of impacts from all BOEM-authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include 

the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of 

beach mouse. 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) are discussed in the MMS (2007b) 

lease sale EIS are no longer listed as endangered or threatened. These are discussed in 

Section C.4.2, Shorebirds and Coastal Nesting 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.

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.

There are no other endangered plants or animal species in the Gulf of Mexico that are

reasonably likely to be effected by either routine or accidental events associated with this EP.

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 a recent 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 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 
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within the home range of the Gulf of Mexico population (within the 95% utilization distribution) 

(Jochens et al., 2008).

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 2012-BSEE-G01 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 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; BOEM, 2012). 

Potential 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 mid-frequency hearing, but the available data do not indicate a consistent 

response to anthropogenic noise (Southall et al., 2007). Noise intensity associated with drilling 

is relatively weak, and the noise exposure of an individual animal 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 noise 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. 

NMFS analyzed the potential for impacts of drilling-related noise on sperm whales in its 

Biological Opinion for the Gulf of Mexico Oil and Gas Activities: Five-Year Leasing Plan for 

Western and Central Planning Areas 2007-2012 (NMFS, 2007). The analysis noted that 

semisubmersible drilling rigs emit 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 were not identified as IPFs for sperm whales in recent lease 

sale EISs (MMS, 2007b, 2008) or the NMFS (2007) Biological Opinion.

Potential 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 are presented in a recent lease sale EIS 

(MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued 

NTL 2012-JOINT-G01, 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 
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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 safety permits,

when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an 

underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well 

as reduce the chance for disturbing sperm whales.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales. With 

implementation of the mitigation measures in NTL 2012-JOINT-G01, NMFS concluded that the 

likelihood of collisions between vessels and sperm whales would be reduced to insignificant 

levels. 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 population level. With implementation of the vessel strike 

avoidance measures requirement to maintain a distance of 91 m (300 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 

3 (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 

(Smultea et al., 2008), the NMFS (2007) concluded that this altitude would minimize the 

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

Potential Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent lease 

sale EISs (MMS, 2007b, 2008) and by NMFS (2007). 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 COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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 
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Environmental Impact Analysis for Initial Exploration Plan Page 32 

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 (Marine Mammal Commission [MMC], 2011). 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.

Potential 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 NMFS (2007). 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, 2011). 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, 2011).

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 2012-JOINT-G01 to reduce 

the potential for striking or disturbing these animals.

C.3.2 West Indian Manatee (Endangered)

Most of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001). 

Manatee sightings in Louisiana have increased as the species extends its presence farther west 

of Florida in the warmer months (Wilson, 2003). A species description is presented in a recent 

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 because the 

lease area is approximately 171 miles (275 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 2012-BSEE-G01 will minimize the 

potential for marine debris-related impacts on manatees.
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Potential 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, BSEE and BOEM issued NTL 2012-JOINT-G01, 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 NTL 2012-JOINT-G01 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 relatively low altitudes 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.

Potential Impacts of a Large Oil Spill (WCD)

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, 2011). 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, changes to foraging distribution and/or patterns, changing reproductive 

behavior/productivity, and changing movement patterns or migration (MMC, 2011).

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 2012-JOINT-G01 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 

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. NMFS did not include 
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Environmental Impact Analysis for Initial Exploration Plan Page 34 

any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007). 

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. This includes 2 mysticete 

whales, the dwarf and pygmy sperm whales, 4 species of beaked whales, and 14 species of 

delphinids. All marine mammals are protected species under the MMPA. 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 a recent lease sale 

EIS (MMS, 2007b).

Mysticete whales. Two species of 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 water depths 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.

Delphinids. 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), 
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Environmental Impact Analysis for Initial Exploration Plan Page 35 

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

dolphin (Stenella coeruleoalba). Any of these species could occur in the lease area. The most 

common non-endangered cetaceans in the deepwater environment are the pantropical spotted 

dolphin, spinner dolphin, and Clymene dolphin.

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 (WCD). 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 2012-BSEE-G01 will 

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

Potential 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 those produced 

by OCS drilling activities (Richardson et al., 1995). Noise intensity associated with drilling is 

relatively weak, and the noise exposure of an individual animal 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 recent 

lease sale EISs (MMS, 2007b, 2008).

Potential 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 are presented in a recent lease 

sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued 

NTL 2012-JOINT-G01, 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 

NTL 2012-JOINT-G01 will 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).
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Potential 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 COP’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of COP’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, 2011). 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.

Potential Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2000, 2007b, 

2008; BOEMRE, 2011; BOEM, 2012). 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, 2011). 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, 2011).

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 2012-JOINT-G01 to 

reduce the potential for striking or disturbing these animals, and therefore no significant 

impacts are expected. 
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Environmental Impact Analysis for Initial Exploration Plan Page 37 

Data from the Macondo spill indicate that numerous marine mammals could be affected by a 

large spill. According to NMFS (2011a), through April 2011, 157 dead marine mammals were 

reported, of which most were bottlenose dolphins. Other affected species included 

dwarf/pygmy sperm whale, melon-headed whales, and spinner dolphins. Because of known low 

detection rates of carcasses, it is possible that the number of marine mammal deaths is 

significantly underestimated (Williams et al., 2011). Also, necropsies to confirm the cause of 

death could not be conducted for many of these marine mammals, and it is possible that some 

were not related to the Macondo spill.

C.3.5 Sea Turtles (Endangered/Threatened)

Five species of endangered or threatened sea turtles may be found near the lease area. 

Leatherback (Dermochelys coriacea), Kemp's ridley (Lepidochelys kempii), and hawksbill 

(Eretmochelys imbricata) turtles are endangered. The Northwest Atlantic Ocean distinct 

population segment of the loggerhead turtle (Caretta caretta) is classified as threatened 

(76 FR 58868). 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 MMS (2007b).

The extent and scope of the Macondo spill represents new information not assessed in the 

existing ESA Section 7 consultation under the current Five-Year Program. As a result of this new 

information, BOEM reinitiated ESA Section 7 consultation on the existing Gulf of Mexico lease 

sale EIS with NMFS and the USFWS on 30 July 2010. However, NMFS and the USFWS have 

placed the consultation process on hold pending the results of the NRDA post-Macondo spill 

data review, which has yet to be released. The existing consultation currently remains in effect 

(BOEM, 2012). 

BOEMRE (2011) and BOEM (2012) reexamined the impacts analyses presented in MMS (2007b, 

2008) for the five sea turtle species that inhabit the Gulf of Mexico based on additional 

information and in consideration of the Macondo spill. No new information was found that 

would alter the potential impacts on sea turtles described in previous EISs. 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 

turtle species 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 

(Florida Fish and Wildlife Conservation Commission, 2012a) and, to a lesser extent, from 

Texas through Alabama (NMFS and USFWS, 2008). 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, 2012b,c);
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• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, 

Tamaulipas, Mexico (NMFS et al., 2011). 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, 2012); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area

(USFWS, 2011a). 

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 

(WCD). 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 of the discharges. 

Compliance with NTL 2012-BSEE-G01 will minimize the potential for marine debris-related 

impacts on sea turtles.

Potential 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.

Potential Impacts of 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, BSEE and BOEM issued NTL 2012-JOINT-G01, 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. 
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This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are 

expected.

Potential Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008) and the 

NMFS Biological Opinion (NMFS, 2007). 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 COP’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of COP’s OSRP is expected to minimize 

potential impacts on sea turtles. 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.

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. 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 171 miles (275 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. 

Potential 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. In the unlikely event of a 

spill, implementation of COP’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.
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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).

The OSRA results summarized in Table 3 predict that Texas and Louisiana shorelines that 

support limited sea turtle nesting could be contacted within 30 days. The nearest nesting area 

of loggerhead turtles is found in St. Bernard Parish, Louisiana, on beaches within the Breton 

NWR. This area is not expected to be contacted within 30 days. The 120-day OSRA modeling 

estimates no contacts with Alabama and Florida Panhandle shorelines that support significant 

loggerhead sea turtle nesting within 30 days and a maximum contact probability of 1% for these 

areas within 120 days (BOEM, 2012). 

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 

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 2012-JOINT-G01 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 a 

recent 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). 
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Figure 3. Location of selected environmental features in relation to the lease area.
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Potential Impacts of a Large Oil Spill (WCD)

The lease area is 171 miles (275 km) from the nearest shorelines inhabited by Piping Plovers 

(Figure 3). The OSRA results summarized in Table 3 indicate that Texas and Louisiana shorelines 

designated as critical habitat for the wintering Piping Plover could be contacted by a spill within 

30 days. The highest probability of shoreline contact after 30 days is for Cameron Parish, 

Louisiana (3%). 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. COP has 

extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching 

the shoreline, as detailed in the OSRP.

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, 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 (Whooping Crane Eastern Partnership, 2010). 

A nonmigrating population has been reintroduced in central Florida, and another reintroduced 

population summers in Wisconsin and migrates to the southeastern United States 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. 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. 

Potential Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately 

358 miles (576 km) from its critical habitat designated in the Aransas NWR. The OSRA results 

summarized in Section A.9.3 (Table 3) predicts no contacts with shorelines of the Aransas NWR 

(Calhoun County, Texas) within 30 days. The supplemental OSRA modeling (BOEM, 2012) 

predicts that contact probabilities for Calhoun County range seasonally from <1% to 6% after 

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 Whooping Crane deaths could occur. In the event of a 
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spill, COP 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 today 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). 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 a recent lease sale EIS (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 fish. 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). 

Potential Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in recent EISs (MMS, 2007b, 2008; 

BOEMRE, 2011; BOEM, 2012) and by NMFS (2007). For this EP, there are no unique site-specific 

issues with respect to this species.

The lease area is approximately 242 miles (389 km) from the nearest Gulf sturgeon critical 

habitat. The OSRA modeling (Table 3) estimates no contacts with coastal areas inhabited by 

Gulf sturgeon within 30 days. The additional OSRA modeling (BOEM, 2012) predicts that a spill 

in the lease area has 2% or less probability of contacting any coastal areas inhabited by Gulf 

sturgeon within 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 from 

1 September through 30 April when this species is foraging in estuarine and shallow marine 

habitats (NMFS, 2007).

C.3.9 Beach Mice (Endangered)

Four subspecies of endangered beach mouse (Peromyscus polionotus) occur on the barrier 

islands of Alabama and the Florida Panhandle: the Alabama, Choctawhatchee, Perdido Key, and 

St. Andrew beach mice. Critical habitat has been designated for all four subspecies; Figure 3
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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 Section A.9.2). 

Potential Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in recent 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 310 miles (499 km) northeast from the nearest beach mouse critical 

habitat. The OSRA modeling summarized in Section A.9.3 (Table 3) predicts no contacts with 

Alabama and Florida shorelines inhabited by beach mice within 30 days. The additional OSRA 

modeling by BOEM (2012) 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.

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 area (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 

(shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Sooty Tern, 

Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); 

and permanent resident species (Laughing Gulls, Royal Terns, Bridled Terns) (Hess and 

Ribic, 2000).
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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’s 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. 

The GulfCet II study 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 (WCD). Effluent discharges are likely to have negligible 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 2012-BSEE-G01 will minimize the potential for 

marine debris-related impacts on birds.

Potential 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 described 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). In 

laboratory experiments, Poot et al., (2008) found the magnetic compass of migratory birds to be 

wavelength dependent. Migratory birds require light from the blue-green part of the spectrum 

for magnetic compass orientation, whereas red light (visible long-wavelength) disrupts their 

magnetic orientation. A field study was designed to test if and how changing light color 
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influenced migrating birds under field conditions. It was found that nocturnally migrating birds 

were disoriented and attracted by red and white light (containing visible long-wavelength 

radiation), whereas they were clearly less disoriented by blue and green light (containing less or 

no visible long-wavelength radiation) (Poot et al., 2008). 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 versus 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.

Potential 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.

Potential 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 COP’s preventative measures during routine 

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

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.

Potential 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.

BOEM has reexamined the analyses for coastal and marine birds presented in MMS (2007b, 

2008) and determined that no new information was found that would alter the potential 

impacts on marine and pelagic birds (BOEMRE, 2011; BOEM, 2012).
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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 (USFWS, 2011b). 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 

Commission, 2011). 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 lives 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 United States, 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 because the lease area is 171 miles (275 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 2012-BSEE-G01 will minimize the potential for marine debris-related impacts on shorebirds.
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Potential Impacts of Support Vessel and Helicopter Traffic

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

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 COP’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 guidelines in effect, it is likely that individual birds would experience, at most, 

only short-term behavioral disruption.

Potential Impacts of Large Oil Spill (WCD)

Data from the Macondo spill provide additional information about the species of coastal and 

shore birds that may be affected in the event of a catastrophic spill of a similar nature and 

duration. BOEM (2012) provides supplemental information to the analysis presented in the 

lease sale EIS (MMS, 2007b). As of May 12, 2011 (the last publicly available report on collected 

birds), USFWS (2011b) reported that 6,381 total birds were found dead or found alive and later 

died, of which an unknown number of deaths were attributable to the Macondo spill. According 

to the USFWS (2011b), bird species that were 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
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• Forster’s Tern

• Black Tern

• Gull-billed Tern

• Least Tern

• Black Skimmer

• Common Loon

• 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.

While the Macondo spill had direct and indirect impacts to coastal and marine birds, it is 

premature to conclude impacts over a long period (BOEM, 2012). Modeling of Macondo 

spill-related bird impacts is underway by the NRDA, but results have not yet been released. 

Antonio et al. (2011) modeled bird mortality from the Macondo spill showing cumulative carcass 

numbers and mortality rate increasing exponentially from the start of the Macondo spill until 

the mortality rate began to decline after the 97th day of the spill. Note that the collected 

animals would be a small subset of the total number of impacted birds and, therefore, the 

collected animals would represent an underestimated measure of the overall impact of the 

Deepwater Horizon event (BOEM, 2012).

Coastal birds can be exposed to oil as they float on the water 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.

As noted above, the Brown Pelican was recently removed from the Federal 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 
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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).

Potential 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 (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.

Potential 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 

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.

Potential Impacts of Water Intakes

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery 

on the drilling rig. The estimated intake and discharge rate of cooling water is 140,000 BPD 

(5.88 MGD) and another 140,000 BPD (5.88 MGD) for fire water.

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 reduce the potential for adverse environmental impacts from impingement and 
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entrainment of aquatic organisms. All affected intakes will be in accordance with the design, 

monitoring, and recordkeeping requirements of the NPDES permit.

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.

Potential 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 COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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, a small fuel spill would 

be unlikely to produce detectable impacts on pelagic communities.

Potential 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 and they will die if exposed to certain toxic fractions of spilled oil. 

Impacts potentially would be greater if local-scale currents retained planktonic larval 

assemblages (and the floating oil slick) within the same water mass.

The BOEM (2012) has reexamined the analysis for fish resources, including ichthyoplankton, in 

consideration of the Macondo event. Although there remains incomplete or unavailable 

information on the impacts of the Macondo event, BOEM (2012) found there was no substantial 
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new information that would alter the impact conclusions for fish resources and EFH presented in 

previous EISs (MMS, 2007a,b).

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 BOEM (2012) has reexamined the analysis for fish resources and EFH presented in recent 

lease EISs (MMS, 2007a,b), in consideration of the Macondo event. No substantial new 

information was found that would alter the impact conclusions for fish resources and EFH 

presented in MMS (2007a,b).

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management 

Plans for corals and coral reefs, shrimps, stone crab, spiny lobster, reef fishes, coastal migratory 

pelagic fishes, and red drum. 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, which is located 92 miles (148 km) north-northwest of the 

lease area.

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 the following species and life stages

(NMFS, 2009):

• Albacore tuna (adults)

• Atlantic bigeye tuna (adults)

• Atlantic bluefin tuna (spawn, eggs, 

larvae, adults)

• Blue marlin (juveniles, adults)

• Common thresher shark (all)

• Longbill spearfish (juveniles, adults)

• Longfin mako shark (all)

• Oceanic whitetip shark (all)

• Skipjack tuna (spawn, adults)

• Swordfish (larvae, juveniles, adults)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, 

adults)

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).
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On 27 May 2011, after an extensive scientific review, NMFS announced that Atlantic bluefin 

tuna currently do not warrant species protection under the ESA (NMFS, 2011b). However, 

NMFS classified the tuna as a species of concern, effectively placing it on a watch list as the 

agency awaits new data on the impact of a stricter international management regimen. 

A new amendment to the original EFH Generic Amendment was finalized in 2005

(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. The Highly Migratory Species Fisheries Management Plan was amended in 2009 

to update EFH and HAPC to include the bluefin tuna spawning area (NMFS, 2009).

There are current NTLs (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 BOEM’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 followed 

(BOEMRE, 2011; BOEM, 2012).

Other HAPCs have been identified 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 Jakkula Bank, located approximately 103 miles (166 km)

north-northwest 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).

Potential 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.

Potential 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, fire water, and 

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.
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Potential 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.

Potential Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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 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 coral EFH is located 

92 miles (148 km) north-northwest of the lease area. A small fuel spill would float and dissipate 

on the sea surface and would not contact these features.

Potential 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 crab, spiny 

lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse 

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. 
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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 closest sensitive habitat (topographic high, pinnacle area, or coral EFH) to the lease area is a 

coral EFH, located 92 miles (148 km) north-northwest of the lease area. An accidental spill 

would be unlikely to affect this area, since a surface slick would not reach these features due to 

their depth.

C.6 Archaeological Resources

C.6.1 Shipwreck Sites

WR 416 and 460 are not on the list of lease blocks with a high potential for historic shipwrecks. 

As required by 30 CFR 550.194(a)(2), an archaeological assessment survey was conducted by 

Fugro (2012) which indicated that there is no evidence of shipwrecks or other archaeological 

resources near the proposed surface locations.

Should there be any indication that potential shipwreck sites could be affected, in accordance 

with NTL 2005-G07, COP will immediately halt operations, take steps to ensure that the site is 

not disturbed in any way, and contact the BOEM Regional Supervisor, Leasing and Environment, 

within 48 hours of its discovery. COP would cease all operations within 305 m (1,000 ft) of the 

site until the Regional Supervisor provides instructions on steps to take to assess the site’s 

potential historic significance and protect it.

Because there are no known shipwreck sites in the lease area, there are no routine IPFs that are 

likely to affect shipwrecks or other archaeological resources in these blocks. A small fuel spill 

would not affect shipwrecks because the oil would float and dissipate on the sea surface. 

Therefore, a large oil spill (WCD) is the only IPF considered.

Potential Impacts of a Large Oil Spill (WCD)

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, COP will take 
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appropriate steps to limit any potential impact and will contact the BOEM Regional Supervisor, 

Leasing and Environment within 48 hours of its discovery. 

A spill entering shallow coastal waters could conceivably contaminate an undiscovered 

shipwreck site. The OSRA modeling summarized in Table 3 predicts that Texas and Louisiana 

shorelines could be contacted by a spill within 30 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

The wellsites are in water depths ranging from 2,108 to 2,193 m (6,915 to 7,195 ft), which is well 

beyond the 60-m (197-ft) depth contour used by the BOEM as the seaward extent for 

prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric 

archaeological sites are not expected to be present in the lease area, the only relevant accident

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.

Potential Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not expected to be present 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 OSRA modeling 

summarized in Table 3 estimates that Texas and Louisiana shorelines could be contacted by a 

spill within 30 days and the 120-day OSRA model estimates that Mississippi, Alabama, and 

Florida coastlines could be contacted 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, the only IPF associated with routine activities in the lease area 

that potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, 

wilderness areas, or any other managed or protected coastal area is related to support vessel 

traffic. The primary support bases at Port Fourchon and Amelia, Louisiana are not in wildlife 
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refuges or wilderness areas. 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 

171 miles (275 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.

Potential 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 or protected areas. Over time with a large 

number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. 

Impacts will be minimized by following the speed and wake restrictions in harbors and channels.

Potential 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 OSRA modeling summarized in Table 3 predicts that shorelines of Texas and Louisiana could 

be affected within 30 days. Cameron Parish, Louisiana, has the highest potential of contact for 

the 30-day interval (3%). After 30 days, four Texas counties and four Louisiana parishes may be 

contacted, ranging from Matagorda County, Texas, to Plaquemines Parish, Louisiana (BOEM, 

2012). 

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. NWRs and other protected areas along the 

coast are discussed in a recent lease sale EIS (MMS, 2007b) and COP’s OSRP. Coastal and near 

coastal wildlife refuges, wilderness areas, and State and National parks within the geographic 

range of the potential shoreline contacts within 30 days are presented in Table 6. 

Additional coastal areas could be contacted in the event of a spill persisting for more than 

30 days. In the 120-day OSRA modeling (BOEM, 2012), potential shoreline contacts after 

120 days ranged from Cameron County, Texas (at the Texas/Mexico border) to Dade County in

southeastern Florida. These areas include habitats such as barrier beach and dune systems, 

wetlands, and submerged seagrass beds that support diverse wildlife, including endangered or 

threatened species. However, in the 120-day OSRA modeling, counties or parishes with greater 

than 10% contact probability during any season ranged from Matagorda County, Texas, to 

Plaquemines Parish, Louisiana, which is identical to the geographic range identified in the 

30-day OSRA modeling.
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Table 6. Wildlife refuges, wilderness areas, and State and National parks within the geographic 

range of the potential shoreline contacts within 30 days following an oil spill in the 

lease area. See Table 3 for contact probabilities of individual shoreline segments. 

County or Parish, State Wildlife Refuge, Wilderness Area, or

State/National Park

Matagorda County, Texas 

Big Boggy National Wildlife Refuge

Aransas National Wildlife Refuge

Mad Island Wildlife Management Area

San Bernard National Wildlife Refuge

Brazoria County, Texas

San Bernard National Wildlife Refuge

Peach Point Wildlife Management Area

Brazoria National Wildlife Refuge

Christmas Bay Coastal Preserve and Christmas Bay State Park 

Galveston County, Texas

Brazoria National Wildlife Refuge

Galveston Island State Park

Apffel Park

Seawolf Park

Old Fort Travis Park

Atkinson Island Wildlife Management Area

Ft. Anahuac Park

Anahuac National Wildlife Refuge

McFaddin National Wildlife Refuge

Candy Abshier Wildlife Management Area

Atkinson Island Wildlife Management Area

Jefferson County, Texas 

McFaddin National Wildlife Refuge

Sea Rim State Park

J.D. Murphree Wildlife Management Area

Texas Point National Wildlife Refuge

Cameron Parish, Louisiana 

Sabine National Wildlife Refuge

Cameron Prairie National Wildlife Refuge

Lacassine National Wildlife Refuge

Little Pecan Island Natural Area

Peveto Woods Natural Area

Lower Neches Wildlife Management Area

Rockefeller Wildlife Management Area

Vermilion Parish, Louisiana Louisiana Rockefeller Wildlife Management Area

Paul J. Rainey Wildlife Management Area

Terrebonne Parish, Louisiana

Atchafalaya Delta Wildlife Management Area

Mandalay National Wildlife Refuge

Isles Dernieres Barrier Islands Refuge

Plaquemines Parish, Louisiana

Salvador Wildlife Management Area

Delta National Wildlife Refuge

Pass A Loutre Wildlife Management Area

Breton National Wildlife Refuge

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 

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 
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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).

A blowout resulting in a large oil spill (WCD) is an extremely rare event, and the probability of 

such an event will be minimized by COP’s well control and blowout prevention measures as 

detailed in EP Section B. In the unlikely event of a spill, implementation of COP’s OSRP will 

mitigate and reduce the impacts. EP Section H provides detail on spill response measures. 

Therefore, no significant spill impacts on coastal habitats are expected.

C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in 

MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill. 

No new information was found that would alter the potential impacts on commercial fishing

(BOEMRE, 2011; BOEM, 2012). 

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 FR 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 typically are 10 to 30 m 

(33 to 98 ft) long, and their trips last from about 1 to 3 weeks. The main Gulf of Mexico 
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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 

slope, well inshore of the project area. Royal red shrimp (Pleoticus robustus) are caught by 

trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Tilefishes (primarily 

Lophalotilus chamaeleonticeps) 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 types of potential accidents are also addressed below – a small fuel spill and a large 

oil spill (WCD).

Potential 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.

Potential Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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).
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Potential 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 

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, 2011c). At its peak on 2 June 2010, closures 

encompassed 88,522 mi2 (229,270 km2

), or 36.6% of the U.S. Exclusive Economic Zone in the 

Gulf of Mexico. BOEM (2012) notes that fisheries closures from a large spill event could have a 

negative effect on short-term fisheries catch and/or marketability.

The BOEM (2012) reexamined the analysis for impacts to commercial fish resources presented 

in recent lease sale EISs (MMS, 2007b, 2008) and found that no substantial newly published, 

peer-reviewed information was found that would alter the overall conclusion that the potential 

impacts on commercial and recreational fishing activities from an accidental oil spill are 

anticipated to be minimal because the potential for oil spills is very low, because most events 

are small and of short duration, and because the effects are so localized that fishes are typically 

able to avoid the affected area. Fish populations may be affected by an oil spill event should it 

occur, but they would be primarily affected if the oil reaches the productive shelf and estuarine 

areas where many fishes spend a portion of their life cycle. The probability of an offshore spill 

affecting these nearshore environments is also low. BOEM (2012) concludes that impacts on 

catch or value of catch would be insignificant compared with natural variability and other 

pressures affecting the resource.

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.

Potential Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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 171 miles (275 km) from the nearest shoreline (Louisiana)

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).
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Potential 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, 

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. Initial symptoms from cleanup workers 

who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H2S, 

e.g., headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain 

(Solomon and Janssen, 2010). Wildlife cleaning and rehabilitation workers reported concerns 

including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, 

dizzy, or fatigued (King and Gibbins, 2011). Hand, shoulder, or back pain was also reported by 

some wildlife cleaning workers. Awkward postures, repetitive motions, and heavy lifting tasks 

were noted by investigators as contributing to musculoskeletal symptoms. However, the most 

common occupational hazard identified for spill response workers was heat stress from work in 

a hot and humid environment (King and Gibbins, 2011).

A blowout resulting in a large oil spill (WCD) is an extremely rare event, and the probability of 

such an event will be minimized by COP’s well control and blowout prevention measures as 

detailed in EP Section H. In the unlikely event of a spill large enough to require extensive use of 

subcontracted cleanup labor, compliance with COP’s OSRP and subcontractor HSE requirements 

as well as NOAA and the Occupational Safety and Health Administration (OSHA) requirements 

will eliminated or minimize the potential for such adverse impacts to the work force.

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.

Potential Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by COP’s preventative measures during routine 

operations, including fuel transfer. In the unlikely event of a spill, implementation of COP’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.
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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 171 miles (275 km) from the nearest shoreline. Based on the 30-day 

OSRA modeling as summarized in Table 3, as well as the 120-day modeling by BOEM (2012), 

Texas and Louisiana coastal areas have the most potential to be affected by a spill. Potential 

shoreline contacts after 120 days range from Cameron County, Texas (at the Texas/Mexico 

border) to Dade County in southeastern Florida (BOEM, 2012). 

In addition to the analyses presented by MMS (2007b, 2008) and BOEM (2012), 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 six-month period; this direct reduction in spending 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). 

As noted by BOEM (2012), the short-term social and economic consequences for the Gulf coast 

region should a large spill occur include the opportunity cost of employment and expenditures 

that could have gone to production or consumption rather the spill cleanup efforts. Nonmarket 

effects such as traffic congestion, strains on public services, shortages of commodities or 

services, and disruptions to the normal patterns of activities or expectations could also occur in 

the short term. These negative, short-term social and economic consequences of a spill are 

expected to be modest in terms of projected cleanup expenditures and the number of people 

employed in cleanup and remediation activities (BOEM, 2012). Net employment impacts from a 

spill would not be expected to exceed 1% of baseline employment in any given year 

(BOEM, 2012). 

C.8.4 Recreation and Tourism

BOEM has reexamined the analyses for recreation and tourism presented in MMS (2007b, 2008) 

based on additional information and in consideration of the Macondo oil spill event. No new 

information was found that would alter the potential impacts on recreation and tourism 

(BOEMRE, 2011; BOEM, 2012).

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. 
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Compliance with NTL 2012-BSEE-G01 will minimize the chance of trash or debris being lost 

overboard from the drilling rig and subsequently washing up on beaches.

Potential Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by COP’s preventative measures during routine 

operations including fuel transfer. In the unlikely event of a spill, implementation of COP’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; BOEM, 2012). 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 

30-day OSRA modeling as summarized in Table 3, as well as the 120-day OSRA modeling by 

BOEM (2012), Texas and Louisiana shorelines are the areas with the most potential to be 

contacted by a spill. However, potential shoreline contacts after 120 days range from 

Cameron County, Texas (at the Texas/Mexico border) to Dade County in southeastern Florida 

(BOEM, 2012). 

According to BOEM (2012), should an oil spill occur and contact a beach area or other 

recreational resource, it would cause some disruption during the impact and cleanup phases of 

the spill. However, these effects may be small in scale and of short duration depending on the 

size of the spill and the extent of the contact. In the unlikely event that a spill occurs that is 

sufficiently large enough to affect large areas of the coast and, through public perception, have 

effects that reach beyond the damaged area, effects to recreation and tourism could be 

significant (BOEM, 2012). 

In addition to the analysis presented by MMS (2007b, 2008) and BOEM (2012), 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 

three-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; 

BOEM, 2012). 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 
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Environmental Impact Analysis for Initial Exploration Plan Page 65 

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. 

A large oil spill (WCD) is the only relevant accident 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.

Potential 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.

According to BOEM (2012), there is low probability that an accidental oil spill will significantly 

affect land use and coastal infrastructure in the region, in part because an offshore spill would 

have a small probability of contacting onshore resources. 

C.8.6 Other Marine Uses

The lease area is not located within any USCG-designated fairway or shipping lane. The lease 

area is not located within a Military Warning Area. There are no existing man-made seabed 

infrastructures within 610 m (2,000 ft) of the proposed wellsites (Gardline, 2012).

There are no IPFs from routine project activities that are likely to affect other marine uses of the 

lease area. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not 

have any impacts on other marine uses because spill response activities would be mainly within 

the lease area and the duration would be brief.

Potential Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The 

blocks are 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. COP will comply with BOEM requirements and lease 

stipulations to avoid impacts on uses of the area by military vessels and aircraft.

C.9 Cumulative Impacts

For purposes of NEPA, cumulative impact is defined as “the impact on the environment which 

results from the incremental impact of the action when added to other past, present, and 

reasonably foreseeable future actions regardless of what agency (Federal or non-Federal) or 

person undertakes such other actions” (40 CFR 1508.7). Any single activity or action may have a 

negligible impact(s) by itself, but when combined with impacts from other activities in the same 

area and/or time period, substantial impacts may result.
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Prior Studies. The BOEM and MMS also recently analyzed the cumulative impacts of 

OCS development activities similar to those planned in this EP in several documents. The level 

and types of activities planned in COP's EP are within the range of activities described and 

evaluated in the Final EIS for Gulf of Mexico OCS Oil and Gas Lease Sales 2007-2012: Western 

Planning Area Sales 204, 207, 210, 215, and 218, and Central Planning Area Sales 205, 206, 208, 

213, 216, and 222 (MMS, 2007b), as updated by a 2008 Final Supplemental EIS for Gulf of 

Mexico OCS Oil and Gas Lease Sales 2009-2012: Central Planning Area Sales 208, 213, 216, and 

222 and Western Planning Area Sales 210, 215, and 218 (MMS, 2008), as well as Final 

Supplemental EIS for Gulf of Mexico OCS Oil and Gas Lease Sale 2012: Central Planning Area 

Sale 216/222 (BOEM, 2012). Past, present, and reasonably foreseeable activities were identified 

in the cumulative effects scenario. These documents are incorporated by reference.

Cumulative Impacts of Activities in the Initial EP

The BOEM (2012) Central Planning Area lease sale EIS analyzed the environmental and 

socioeconomic impacts from the proposed lease sale, OCS program, and other activities 

affecting the resources, ecosystems, and human environment other than the proposed action 

including both human-induced and natural phenomena. The cumulative impacts analysis 

provides a discussion of all impacts (including non-OCS activities) projected to occur from past, 

proposed, and foreseeable future activities that have taken or will take place within the 

geographic area of the Central Planning Area during the 40-year period of 2010 to 2050.

. The MMS (2007b) multi-lease-sale EIS included 

a lengthy discussion of cumulative impacts, which analyzed the environmental and 

socioeconomic impacts from the incremental impact of the 11 proposed lease sales, in addition 

to all activities (including non-OCS activities) projected to occur from past, proposed, and future 

lease sales during the 40-year period of 2007 to 2046 (see EIS page 4-301). The EIS considered 

exploration, delineation, and development wells; platform installation; service-vessel trips; and 

oil spills. The EIS examined the potential cumulative effects on each specific resource for the 

entire Gulf of Mexico.

The level and type of activity proposed in COP’s Initial EP are within the range of activities 

described and evaluated in the recent multi-lease-sale EISs and Central Planning Area EIS. The 

numerous new safety measures implemented by the BOEM and BSEE and the mitigation and 

safety measures proposed by COP in its Initial EP reduce the likelihood of a large spill and 

improve the effectiveness of any response in the extremely unlikely event that another large 

spill occurs. Thus, for all impacts, the incremental contribution of COP’s proposed actions to the 

cumulative impacts analysis in these prior analyses is not significant.

D. Environmental Hazards

D.1 Geologic Hazards

Well clearance letters prepared by Gardline (2012) concluded that the wellsites are free of any 

significant geological hazards and are suitable for the proposed activities. See EP Section C for 

supporting geological and geophysical information.
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Environmental Impact Analysis for Initial Exploration Plan Page 67 

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 rigs under consideration for this project. 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 rigs under 

consideration for this project. 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 alternate wellsite locations and the selection of a drilling unit, 

were considered by COP in developing the proposed action.

F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and 

BOEM 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 COP’s OSRP and will include 

the measures described in EP Section H. 

G. Consultation

No persons or agencies were consulted during the preparation of this EIA.
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Environmental Impact Analysis for Initial Exploration Plan Page 68 

H. Preparers

The EIA was prepared by CSA International, Inc. Contributors included

• Deborah Fawcett (Project Scientist 2);

• Neal Phillips, Ph.D. (Senior Scientist);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director); and

• Kim Dunleavy (Technical Editor).

I. References 

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Science & Technology Bulletin, Vol. 6, No. 5/6, pp. 303-321. Elsevier Science Ltd., PII: S1353-2561(01) 

00049-4. U.S. Minerals Management Service, Herndon, VA.

Antonio, F.J., R.S. Mendes, and S.M. Thomaz. 2011. Identifying and modeling patterns of tetrapod vertebrate 

mortality rates in the Gulf of Mexico oil spill. Aquatic Toxicology 105(1-2):177-179.

Barkuloo, J.M. 1988. Report on the conservation status of the Gulf of Mexico sturgeon, Acipenser oxyrinchus 

desotoi. U.S. Department of the Interior, U.S. Fish Wildlife Service, Panama City, FL. 33 pp.

Bélanger, L. and J. Bédard. 1989. Responses of Staging Greater Snow Geese to Human Disturbance. Journal of 

Wildlife Management 53:713-719.

Biggs, D.C. and P.H. Ressler. 2000. Water column biology, pp. 141-187. In: Continental Shelf Associates, Inc. 

Deepwater Program: Gulf of Mexico Deepwater Information Resources Data Search and Literature Synthesis. 

Volume I: Narrative Report. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico 

OCS Region, New Orleans, LA. OCS Study MMS 2000-049.

Boehm, P., D. Turton, A. Raval, D. Caudle, D. French, N. Rabalais, R. Spies, and J. Johnson. 2001. Deepwater 

program: Literature review, environmental risks of chemical products used in Gulf of Mexico deepwater oil 

and gas operations. Volume I: Technical report. U.S. Department of the Interior, Minerals Management 

Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2001-011. 326 pp.

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SECTION P 

ADMINISTRATIVE INFORMATION 

(A) EXEMPTED INFORMATION DESCRIPTION 

The proposed bottom-hole locations of the planned wells have been removed from the Public 

Information copies of the EP as well as any information concerning the target objectives, geologic or 

geophysical data, and any interpreted geology or subsurface information. 

(B) BIBLIOGRAPHY 

1. Gardline Surveys, Inc. 3D Geohazard Assessment Walker Ridge Blocks 416, 417, 460 and 461. 

2. Fugro Geoservices, Inc. Archaeological Assessment Walker Ridge Blocks 416, 417, 460 and 

 461. Report No. 2412-5002. 

ConocoPhillips Company August, 2012 

Initial Exploration Plan Page P-1 

Walker Ridge Blocks 416 and 460 (OCS-G 32678 and OCS-G 32688)