UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field 

Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - S-07509

Type - Supplemental Exploration Plan

Lease(s) - OCS-G16783 Block - 727 Green Canyon Area

OCS-G18421 Block - 683 Green Canyon Area

Operator - Anadarko Petroleum Corporation

Well No. 002

DP SEMISUBMERSIBLE

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:

December 8, 2011
SUPPLEMENTAL EXPLORATION PLAN 

S-7509 

ANADARKO PETROLEUM 

CORPORATION 

GREEN CANYON BLOCKS 727 & 683 

OCS-G 18421 & 16783 

PUBLIC COPY 

RECORD OF CHANGE LOG 

Submission 

Type 

Date Sent to 

BOEMRE 

Summary of 

Submission 

Page 

Numbers 

Initial 09/14/2011 Submit Supplemental EP All 

Amendment 09/28/2011 Revised H2S Statement 30 

Amendment 10/10/2011 Submit proposed 

directional survey 

N/A 

Amendment 10/31/2011 Send revised waste info 10, 34-35, 55-

56, 58-59 

Final version of EP 11/30/2011 Final copy of plan with 

all revisions included 

All 

Record of Change 

Log 

11/30/2011 Record of Change Log 1 

 
 

PUBLIC 

SUPPLEMENTAL EXPLORATION PLAN 

GREEN CANYON BLOCKS 683 & 727 

OCS-G 18421 & 16783 

OFFSHORE, LOUISIANA

 

Anadarko Petroleum Corporation 

1201 Lake Robbins Drive 

The Woodlands, Texas 77380 

Contact: Jill Fowler 

jill.fowler@anadarko.com 

(832) 636-1554 

1 – Hard Copy Confidential 

1 – CD Confidential 

1 – Hard Copy Public Information 

3 – CDs Public Information

September, 2011 
 

SUPPLEMENTAL EXPLORATION PLAN 

LEASE OCS-G 18421 & 16783 

GREEN CANYON BLOCKS 683 & 727 

 A. Plan Contents 

 B. General Information 

 C. Geological, Geophysical 

D. Hydrogen Sulfide Information 

 E. Biological, Physical and Socioeconomic Information 

F. Wastes and Discharge Information 

 G. Air Emissions Information 

 H. Oil Spill Information 

I. Environmental Monitoring Information 

 J. Lease Stipulations 

 K. Support Vessels and Aircraft Information 

 L. Onshore Support Facilities Information 

M. Coastal Zone Management Act Information 

N. Environmental Impact Analysis 

O. Administrative Information 
 

A 

PLAN CONTENTS

(a) Plan Information Form 

Under this Supplemental Exploration Plan, Anadarko Petroleum Corporation (Anadarko) proposes to drill 

and complete one well. The well will have a surface location in Green Canyon Block 683, and the 

bottom-hole location in Green Canyon Block 727. The well will be drilled using either a Dynamically 

Positioned (DP) Drillship or DP Semisubmersible drilling rig. Drilling and completion operations for the 

proposed well location will utilize a Subsea BOP stack. OCS Plan Information Form MMS-137 is 

enclosed as Attachment A-1. 

(b) Location 

Enclosed as Attachment A-2 is a well location plat at a scale of 1 inch = 2000 feet that depicts the 

surface location and water depth of the proposed well. 

(c) Safety and Pollution Prevention Features 

Safety features on the drilling unit will include well control, pollution prevention, safe welding 

procedures, and blowout prevention equipment as described in Title 30 CFR Part 250, Subparts C, D, E, 

G and O; and as further clarified by BOEM Notices to Lessees, and applicable regulations of the 

Environmental Protection Agency and the U.S. Coast Guard. The appropriate life rafts, life jackets, ring 

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

(d) Storage Tanks and Production Vessels 

The Green Canyon Block 683/727 well will be drilled with a DP drillship DP semisubmersible unit. 

Type of Facility Type Of Storage 

Tank 

Tank 

Capacity 

Number 

Of Tanks 

Total 

Capacity 

Fluid 

Gravity 

(Api) 

Total 

Capacity of 

all Tanks for 

Rig Type 

Drillship Fuel Oil Storage 

Tank 

16,564 bbls 1 16,564 bbls No. 2 Diesel 6 tanks total= 

36,595.9 bbls 

 Fuel Oil Storage 

Tank 

16,685.5 

bbls 

1 16,685.5 bbls No. 2 Diesel 

 Fuel Oil Settleing 

Tanks 

836.6 bbls 2 1,673.2 bbls No. 2 Diesel 

 Fuel Oil Day Tanks 836.6 bbls 2 1,673.2 bbls No. 2 Diesel 

DP Semi Fuel Oil Hull 

Tanks 

4,541 bbls 2 9,082 bbls No. 2 Diesel 7 tanks total= 

16,689 bbls 

 Fuel Oil Hull 

Tanks 

3,392 bbls 2 6,784 bbls No. 2 Diesel 
 

 Fuel Oil Deck Day 

Tank 

629 bbls 1 629 bbls No. 2 Diesel 

 Fuel Oil Deck 

Settling Tank 

164 bbls 1 164 bbls No. 2 Diesel 

 Fuel Oil 

Emergency 

Generator 

30 bbls 1 30 bbls No. 2 Diesel 

(e) Pollution Prevention Measures 

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

pollution prevention and control. The rig has a Shipboard Oil Pollution Emergency Plan 

(SOPEP), which is reviewed and approved annually by the American Bureau of Shipping (ABS). 

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, logicalm and timely manner. 

Pollution prevention measures include 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 go overboard or into the moonpool, respectively. To prevent ocean discharge 

from the drains there is a dedicated drip pan under the rotary table. 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. They are not meant for permanent storage of waste. On the rare occasion 

that they contain wastes, they are 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. 

(f) Description of Previously Approved Lease Activities 

Anadarko has previously approved well locations in both Green Canyon Block 683 and 727. 

Approval was granted to drill and complete the following well locations under the Initial 

Exploration Plan (filed by Shell) for Green Canyon Block 683 (Plan Control No. N-7797) 

approved on August 8, 2003: 

Well 

Location 

Status of Well Location Potential Future Operations 

A Used location to drill GC 683 #001 

ST02 well. 

Well has been completed; preparing to place on 

production. 

B Well location open. Possible well location for future drilling operations. 

C Well location open. Possible well location for future drilling operations.

D Well location open. Possible well location for future drilling operations.

E Well location open. Possible well location for future drilling operations.
 

Approval was granted to drill and complete the following well locations under the Initial 

Exploration Plan (filed by Shell) for Green Canyon Block 727 (Plan Control No. N-7577) 

approved on December 24, 2002: 

Well 

Location 

Status of Well Location Potential Future Operations 

A Well location open. Possible well location for future drilling operations.

B Well location open. Possible well location for future drilling operations.

C Used location to drill GC 727 #001 

well. 

Well was P&A’d in 2003.

D Well location open. Possible well location for future drilling operations.

E Well location open. Possible well location for future drilling operations.
U.S. Department of the Interior 

Minerals Management Service OCS PLAN INFORMATION FORM 

OMB Control Number: 1010-0051 

OMB Approval Expires: July 31, 2008 

General Information 

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

Company Name: Anadarko Petroleum Corporation MMS Operator Number: 00981 

Address: 1201 Lake Robbins Drive Contact Person: Jill Fowler 

The Woodlands, TX 77380 Phone Number: (832) 636-1554 

E-Mail Address: Jill.fowler@anadarko.com 

Lease(s): G18421/ G16783 Area: GC Block(s): 683/727 Project Name (If Applicable): Caesar/Tonga 

Objective(s): x Oil x Gas Sulphur Salt Onshore Base: Fourchon, LA Distance to Closest Land (Miles): 120 

Description of Proposed Activities (Mark all that apply) 

x Exploration drilling Development drilling 

x 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 

x 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 an MMS-designated high-probability archaeological area? Yes x No 

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

Tentative Schedule of Proposed Activities 

Proposed Activity Start Date End Date No. of Days 

Drill and complete well 002 in GC 727 04-01-2012 09-28-2012 180 

 

 

 

 

 

Description of Drilling Rig Description of Production Platform 

Jackup X Drillship Caisson Tension leg platform 

Gorilla Jackup Platform rig Well protector Compliant tower 

Semisubmersible Submersible Fixed platform Guyed tower 

X 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) 

 

 

 

MMS FORM MMS-137 (July 2005 – Supersedes all previous editions of form MMS-137, which may not be used.) Page 1 of 5 
OCS PLAN INFORMATION FORM 

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

Proposed Well/Structure Location 

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

002 

Subsea Completion 

Anchor Radius (if applicable) in feet: 

N/A x Yes No 

Surface Location Bottom-Hole Location (For Wells) 

Lease No. 

OCS-G 18421 

Area Name 

Green Canyon 

Block No. 

683 

N/S Departure: 519’ FSL 

Blockline 

Departures 

(in feet) 

E/W Departure: 7706’ FWL 

X: 2,352,025.5 

Lambert X-Y 

coordinates 

Y: 9,900,518.6 

Latitude 27.26644902 

Latitude/ 

Longitude 

Longitude 90.8090187 

TVD (Feet) : MD (Feet): Water Depth (Feet): 4,484’ 

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 = 

 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 MMS collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document 

submitted for MMS 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 250.196. 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, or 690 with an accompanying DP 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, Mail Stop 4230, Minerals 

Management Service, 1849 C Street, N.W., Washington, DC 20240. 

MMS FORM MMS-137 (July 2005 – Supersedes all previous editions of form MMS-137, which may not be used.) Page 2 of 5 

 

B 

GENERAL INFORMATION 

(a) Applications and Permits 

Prior to beginning exploration operations the following application(s) will be submitted for 

approval: 

Application/Permit Issuing Agency Status 

Permits to Drill BOEM To be submitted 

(b) Drilling Fluids 

Type of Drilling Fluid Estimated Volume Per Well 

Water-based (NaCl saturated, seawater, 

freshwater, barite) for Pump and Dump 

50,000 bbls per well 

Synthetic-based (internal olefin, ester) 14,000 bbls per well 

Oil-based NA 

(c) New or Unusual Technology 

Anadarko does not propose to use any new or unusual technology to drill the wells proposed in 

this plan. 

(d) Bonding Statement 

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

area-wide bond furnished and maintained according to 30 CFR part 256, subpart I; NTL No. 

2000-G16, “Guidelines for General Lease Surety Bonds,” and National NTL No. 2008-N07, 

“Supplemental Bond Procedures”. 

(e) Oil Spill Financial Responsibility (OSFR) 

Anadarko Petroleum Corporation (Company Number 00981) has demonstrated oil spill financial 

responsibility for the facilities proposed in this EP according to 30 CFR Part 253, and NTL No. 

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

(f) Deepwater Well Control Statement 

Anadarko Petroleum Corporation (Company Number 00981) has the financial capability to drill 

a relief well and conduct other emergency well control operations if required. 

(g) Blowout Scenario

Anadarko prepared this blowout scenario pursuant to guidance provided in NTL No. 2010-N06. The well 

location under this Supplemental EP has been determined to have the highest worst-case discharge rate 
 

for Green Canyon Block 727 and was utilized for the following blowout scenario. Based on NTL No. 

2010-N06 guidance, the maximum hydrocarbon discharge is calculated to be 340,281 BOPD. 

Purpose 

This information provides a generic blowout scenario, additional information regarding any 

potential oil spill, the measures Anadarko Petroleum will take to prevent a blowout, and if 

necessary, promptly respond to manage a blowout scenario if one occurs. The following 

information is pursuant with 30 CFR 250.213(g), 250.219, 250.250 and NTL No. 2010-N06. 

Background 

This section has been developed to document the additional information requirements for 

Exploration Plans as requested by NTL No. 2010-N06. The GC 727 #2 development well will be 

drilled as a directional well from a SHL in GC Block 683 into GC Block 727. 

Information Requirements 

Blowout Scenario 

The GC 727 #2 well will be drilled to the objective sand(s), as outlined in the Geological and 

Geophysical Information section of this Plan, utilizing a MODU rig with a marine riser and subsea BOP. A typical sub-sea wellhead system, conductor, and surface and intermediate casing 

program will be used. 

The Blowout Scenario assumes a hydrocarbon influx occurs from the objective intervals, 

followed by a well control event. The sub-sea BOP and marine riser fails, and a blowout occurs 

at the seabed. The WCD scenario assumes a 13-5/8” x 14” casing string set, 11-7/8” liner set, 

and 10-5/8” x 12-1/4” open hole drilled as per the attached wellbore schematic (Attachment H1). 

Estimated Flow Rate of the Potential Blowout 

Category Supplemental EP 

Type of Activity Development Drilling 

Facility Location (area/block) GC Block 727 

Facility Designation MODU 

Distance to Nearest Shoreline (miles) 120 

Uncontrolled Blowout (volume per day) 340,281 bbl 

Type of Fluid(s) Crude Oil- API gravity 28.9 

a) Potential for the well to bridge over: 

Discussions regarding geologic information are considered proprietary and have been omitted 

from this public copy EP. 

b) Measures to enhance the ability to conduct effective and early intervention in the 

event of a blowout: 

The likelihood of surface intervention to stop a blowout is high and is based on the following 

equipment specific to the MODU that has been contracted to do this drilling program: 
 

 ROV Secondary BOP Control System: The BOP is confirmed to have a ROV 

Intervention Panel and circuits that have the following attributes: 

 Hot stab is capable of closing one set of: 

– Blind-Shear Rams (one set) 

– Pipe Rams (one set) 

– Unlatch the Lower Marine Riser Package 

 ROV hot stab to be function tested in conjunction with the Stump test and tested 

at the same rate and pressure as the pump installed on the ROV used by the rig. 

 BOP panels also can be operated by an ROV from an independent supply boat in 

the event of a loss-of-rig scenario. 

 Deadman/Autoshear Function: The rig is equipped with an automated sequence that 

closes the blind shear rams in the event of any of the following scenarios: 

 Inadvertent disconnect of the LMRP 

 Loss of both hydraulic pressure and electrical supply from the surface BOP 

control system 

No human interface is required once these systems are armed. 

c) Availability of a rig to drill a relief well: 

Per the preliminary Mutual Aid agreements that are being worked between E&P Operators in the 

Gulf of Mexico, Anadarko will select from the best rig option available in the Gulf of Mexico 

fleet if and when it is required for relief well work. As of August 1, 2011, there were 15 

additional rigs capable of operating under these conditions in the Gulf of Mexico. A rig that 

could be used to drill a relief well is the Transocean Discoverer Clear Leader, which is a drill 

ship capable of drilling in 12,000 ft of water without any constraints. The rig is currently under 

contract to Chevron and is on location in Green Canyon Block 640 working on the Tahiti South 

Project. 

There are no nearby platforms from which to drill a relief well. 

It is not feasible to drill a relief well from land. 

d) Rig constraints: 

A rig capable of drilling in 4,500 ft of water with a 15k Stack is required for any relief well 

operations. The Transocean Discoverer Clear Leader drill ship meets theses requirements. 

e) Time taken to mobilize a rig and drill a relief well: 

An estimate of 7-21 days is required to suspend operations on a deepwater GOM well and begin 

drilling the relief well. This assumes 0-14 days to suspend current operations on an existing well 

and 7 days to mobilize and be ready to spud the relief well. The estimated time to drill the relief 

well is 125 days, for a total estimated time of 132-146 days from time of blowout to finishing the 

relief well. The drilling days were based on the proposed days to drill the GC 727 #2 well 

through the objective sands (interval of WCD) with additional time added for ranging. 
 

The time estimate provided for the plan well is inclusive of 'both' drilling 'and' completion 

operations. As a completion is not typically part of relief well operations no time has been 

included for completion operations in the relief well estimate. Therefore the estimated time for a 

relief well should be less than for the plan well. In addition, information and learning from the 

drilling of the original well may provide opportunities to optimize drilling performance for relief 

well operations and thus reduce the required drilling time. 

f) Assumptions and calculations used in approved or proposed Oil Spill Response 

Plan: 

 The Merlin reservoir simulator and Avalon nodal analysis programs were used to 

estimate the WCD for this well. Supporting input data can be found on Data Sheets 1 

through 3 in Section H, and Merlin and Avalon files are included as Electronic 

Attachments 1 and 2. At the seafloor, the estimated worst case discharge for the well 

is 340,281 BOPD based on the objective sand intervals.

 The maximum total volume during a blowout could potentially be 49,681,026 bbl 

assuming 146 days for the maximum duration of a blowout, multiplied by the worst case 

daily uncontrolled blowout volume of 340,281 bbl. 

g) Measures taken to reduce the likelihood of a blowout: 

 Well Design: Anadarko utilizes a systematic well design process for the planning and 

construction of a well operation. This process taps into the vast depth of experience 

Anadarko possesses in the Deep Water drilling arena and involves a multi-team peer 

review of the well design, shallow hazards, and formation pressure hazards expected 

during drilling. This process minimizes the potential for an unplanned well control event 

that could lead to a blowout. This process will also include a Registered Professional 

Engineer review and approval of the final casing design and cementing program. 

A detailed pre-drill assessment of formation pressure provided by Anadarko’s Geological and 

Geophysical team, along with third-party consultants, allows for a mud program that provides an 

overbalanced mud weight for the safe drilling of the well. For an exploration well, this may also 

include taking formation pressures to confirm the actual formation pressure during the well 

construction process to minimize the risk of an unplanned well control event. The pore pressure 

environment is understood due to the nearby offset wells. 

The well construction process also requires a systematic review and management acceptance of 

the start-up preparation work for the rig and crews and the third-party technical audit work on the 

rig and the rig’s well control equipment. This measures the rig’s ability to handle an unplanned 

well control event and provide assurance that the rig can successfully mitigate a loss of well 

control event and prevent it from becoming a blowout scenario. 

 Barrier Philosophy: For all well designs, Anadarko requires and uses a redundant 

barrier philosophy, that being two independent tested barriers, including one mechanical 

barrier, across each flow path during well operations. 

For the final casing string (or liner if it is the final string), there shall be two mechanical barriers 

in addition to cement inside the wellbore. 
 

It is also standard practice to conduct pressure testing, in accordance with the law, to confirm 

integrity on all relevant barriers. 

In addition, all intermediate and production casings returned to the wellhead will be locked down 

before subsequent wellbore construction is proceeded. 

 BOP and Well Control Equipment: The rig will have an 18-3/4” 15k psi BOP with 

primary and secondary BOP control systems. The BOP will have been completely 

recertified compliant to OEM specifications by a qualified third-party. Prior to 

commencement of operations, independent third-party verification will be obtained that 

the sub-sea BOP is designed for the specific equipment on the rig and this specific well 

design. 250.416(f) 

 BOP and Well Control Equipment Testing: To ensure effectiveness of the BOP and 

well control equipment, a testing program will be conducted prior to running the BOP 

and then during the well operations. This testing program will provide compliance with 

current federal regulations for pressure and function testing and will also provide periodic 

assurance on the performance of both primary and secondary BOP control systems 

including actual interface operations with the ROV and the ROV panel. 

 Well Control Training and Drills: Anadarko requires that key nominated onshore and 

offshore positions, including rig contractor personnel, hold a WellCAP or equivalent well 

control training certificate, renewable every two years for the type of floating drilling 

operation being conducted. Anadarko also monitors compliance for its personnel with the 

federal regulations and Sub-Part O for well control training. 

A comprehensive program of well control drills will be conducted offshore to ensure readiness to 

identify and then manage a well control situation and thereby minimize the potential for a well 

control event to lead to a blowout scenario. 

h) Arrangements for drilling a relief well: 

 Anadarko maintains a master agreement with Wild Well Control, Inc. for advice, 

management, engineering, well kick pre- and post-modeling, and resource support for an 

unplanned loss-of-well-control event. If any well control event occurs, Wild Well 

Control, Inc. would be contacted and mobilized if required to support Anadarko’s 

operational team, both in the onshore and offshore locations. 

 The conceptual relief well design is similar to the design of the GC 727 #2 well, in that 

casing weights, grades, and setting points would be identical. A two block wide shallow 

hazard assessment has been completed (and submitted) for GC Blocks 683 and 727. Site 

clearance letters for surface locations in both blocks have been completed and deemed 

acceptable for drilling. A surface location approximately 3,204 ft southwest of the 

proposed well GC 727 #2 surface location has been identified as a suitable SHL for the 

relief well. The potential areas for high density chemo-synthetic communities in the study 

area have been identified and can be avoided. Depending on the nature of the blowout 

scenario, well geometry, and total depth required to intersect the blowout, previously 

submitted surface locations and/or additional surface locations would be submitted and 

all reviewed for best suitability for the location of the relief well if needed. The 
 

conceptual well design is not anticipated to take over 2 days to finalize upon 

initialization. 

 Anadarko’s philosophy is to carry adequate inventory in stock to drill a complete well(s) 

from surface to TD. Back-up long-lead equipment equivalent to the original well design 

will be carried in stock to allow a rapid response. This includes a spare deepwater sub-sea 

wellhead system and the large OD casing (36”, 28”, 22”, 18”, and 16”) and connectors 

required. Smaller OD casing (13 5/8”, 11 7/8”, and 9 7/8”) is considered widely available 

on the ground in the GOM and would be resourced out of existing inventory or from 

suppliers as required. 

 Existing service agreements will be in place for support services, including drilling fluids, 

casing running, cementing, ROVs, solids control, mud logging, directional drilling, 

LWD/MWD, logging, boats, and helicopters. 

 Specialist services for range finding to drill the relief well in close proximity to the 

original wellbore at the reservoir depth will be provided through Vector Magnetics LLC. 

Sperry Drilling/Halliburton and Schlumberger have in-house personnel to supplement 

Vector Magnetics LLC under our existing directional drilling agreements. 
 

C 

GEOLOGICAL AND GEOPHYSICAL INFORMATION 

(a) Geological Description 

Discussions regarding geologic information are considered proprietary and have been 

omitted from this public copy EP. 

(b) Structure Contour Maps 

Current structure maps drawn to the top of each productive hydrocarbon sand showing the entire 

lease block, the surface location of the well and location of geological cross-sections, are 

enclosed as Attachment C-1.

(c) Interpreted 2-D and/or 3-D Seismic Lines 

Interpreted seismic lines are enclosed as Attachment C-2.

(d) Geological Structure Cross-Sections 

Interpreted geological structure cross-sections showing the location and depth of the proposed 

well are enclosed as Attachment C-3.

(e) Shallow Hazards Report 

A Shallow Hazards Report prepared by Geoscience Earth & Marine Services, Inc. (GEMS) for 

Green Canyon Block 683 was previously submitted by Shell Exploration and Production 

Company (Shell) with their Initial Exploration Plan. Both GEMS and Shell have granted 

Anadarko permission to utilize the report for this plan. 

(f) Shallow Hazards Assessment 

Shallow hazards site clearance letter for the proposed surface location in Green Canyon Block 

683 is enclosed as Attachment C-4.

(g) High-resolution Seismic Lines 

High resolution seismic lines are enclosed as Attachment C-5. 

(h) Stratigraphic Column 

A generalized stratigraphic column depicting the well from the seafloor to total depth is included 

as Attachment C-6. 
 

(i) Time Vs. Depth Tables 

The proposed activities under this EP are not considered to be in areas where there is no well 

control. Therefore, a seismic travel time versus depth table is not required per NTL No. 2008-

G04. 
10615 SHADOW WOOD DRIVE 

SUITE 200 

HOUSTON, TEXAS 77043 

Phone: (713) 468-1410 

Fax: (713) 468-1438 

E-mail: gems@gemsinc.com

Wellsite GC 727-2 

July 20, 2011 Project No. 0711-1949 

Anadarko Petroleum Corporation 

1201 Lake Robbins Drive 

The Woodlands, Texas 77380 

Attention: Mr. Todd A. Fowler 

Site Clearance Letter 

Proposed Wellsite GC 727-2 

Block 683 (OCS-G-18421) 

Green Canyon Area 

Gulf of Mexico 

Anadarko Petroleum Corporation, (Anadarko) plans to drill an exploration well in Block 683 of the Green 

Canyon (GC) area, Gulf of Mexico. This letter addresses specific seafloor and subsurface geologic 

conditions to the Top of Salt at a depth of approximately 637 ft below the mudline (bml) at the Proposed 

Wellsite GC 727-2. The following discussion is based on findings provided within the main body of the

geohazard report for Block GC 683 (OCS-G-18421), which was originally submitted to Shell Exploration and 

Production Company (Shell) on April 28, 2003, GEMS Report No. 0103-615 (GEMS, 2003). 

The surface location for Proposed Wellsite GC 727-2 is in the south-central portion of GC 683. The 

proposed location constitutes the newest phase of the development of the Caesar/Tonga field and lies 

approximately 185 ft northwest of the existing GC 683 #1 location. Anadarko provided the following 

coordinates for GC 727-2: 

Proposed Wellsite GC 727-2 

Spheroid & Datum: Clarke 1866, NAD27 

Projection: UTM Zone 15 North, U.S. Survey ft Line Reference Block Calls GC 683 

X: 2,352,025.5 Latitude: 27° 15' 59.36446" N Inline: 2361 7,705.5 ft FWL 

Y: 9,900,518.6 Longitude: 90° 48' 32.46723" W Crossline: 4587 518.6 ft FSL 

Anadarko will drill this well using a dynamically positioned drilling vessel. Our assessment addresses the 

seafloor conditions within a 2,000 ft radius around the proposed wellsite location. 

Attachments 

The page-size maps and figures accompanying this letter have been extracted from the main report’s original 

maps and 3-D data volume and centered on the proposed well location. 

Map GC 727-2-1: Bathymetry Map 

Map GC 727-2-2: Seafloor Rendering 

Map GC 727-2-3: Seafloor Amplitude Rendering 

Map GC 727-2-4: Geologic Features Map 

Figure GC 727-2-1: Portion of Inline 2361 and Crossline 4587 Showing Conditions Beneath 

Proposed Wellsite GC 727-2 
Project No. 0711-1949 

- 2 - Wellsite GC 727-2

Figure GC 727-2-2: Tophole Prognosis Chart, Proposed Wellsite GC 727-2, Green Canyon 

Block 683 

NTL Requirements 

The following report complies with the Bureau of Ocean Energy Management, Regulation, and Enforcement 

(BOEMRE, formerly MMS) Notice to Lessees (NTL’s) 2008-G05 and 2009-G40 (MMS, 2008a and 2010). 

The operator will be required to follow NTL’s 2008-G04 and -G06 with respect to an ROV monitoring 

survey as well as pre- and post-spud ROV visual inspection surveys (MMS, 2008b and 2008c). 

The Federal lease block GC 683 is not considered archaeologically significant (MMS, 2008d); however, 

pursuant to the “Pre-Seabed Disturbance Survey Mitigation” released by the BOEMRE, (BOEMRE, 2011a), 

an archaeological assessment of high-resolution data or video will be required prior to any bottom disturbing 

activities. 

Power Spectrum. According to NTL 2008-G05 (MMS, 2008a), 3-D seismic reflection data may be used for 

shallow hazard assessments with approval from the BOEMRE, Gulf of Mexico Region. A power spectrum 

analysis was conducted from the 3-D seismic data cube licensed to Anadarko to illustrate the data 

parameters. The power spectrum curve (below) was generated within a 500-ft radius of the intersection of 

the inline and crossline at the proposed wellsite. We converted the amplitude vs. frequency spectrum,

generated by the SMT software, to power vs. frequency by squaring the amplitude values as described by J. 

A. Coffeen, 1978.

Power Spectrum Analysis Curve, GC 683, Proposed Wellsite GC 727-2

The section of data between the seafloor and the Top of Salt is highly fractured and deformed as a 

result of the shallow salt mass at the proposed wellsite. The close proximity of the salt has likely 

contributed to some lower frequency content on the 3-D data. 
Project No. 0711-1949 

- 3 - Wellsite GC 727-2

Man-Made Features 

Numerous wells and pipelines are present within and/or surrounding the area of seismic data coverage 

(BOEMRE, 2011b). Table 1 provides a summary of the exploration and development wells drilled within 

the area. 

 Table 1: Existing Wells near Proposed Wellsite GC 727-2 

Surface Area/ 

Block Well Name Operator Well Status Distance/Direction From Proposed Well GC 727-2

GC 683 001 Kerr McGee Side-Tracked/Completed 185 feet/SE 

GC 727 001 Anadarko Petroleum Corp. Temporarily Abandoned 2.3 miles/SW 

GC 726 001 Anadarko Petroleum Corp. Side-Tracked 3.4 miles/SW 

GC 726 SS001 Anadarko Petroleum Corp. Side-Tracked/Completed 3.4 miles/SW 

GC 726 GC 770-1 Anadarko Petroleum Corp. Side-Tracked/Completed 3.4 miles/SW 

GC 639 001 Eni US Operating Co. Inc. Drilling Suspended 3.6 miles/NE 

GC 640 002 Chevron USA Inc. Side-Tracked 4.9 miles/NE 

GC 640 PS001 Chevron USA Inc. Side-Tracked/Completed 4.9 miles/NE 

GC 640 PS002 Chevron USA Inc. Completed 4.9 miles/NE 

GC 640 PS003 Chevron USA Inc. Side-Tracked 4.9 miles/NE 

GC 640 PS004 Chevron USA Inc. Application for Permit to 

Drill 4.9 miles/NE 

GC 640 PS005 Chevron USA Inc. Application for Permit to 

Drill 4.9 miles/NE 

GC 640 PS006 Chevron USA Inc. Application for Permit to 

Drill 4.9 miles/NE 

GC 640 PS007 Chevron USA Inc. Application for Permit to 

Drill 4.9 miles/NE 

GC 640 PS008 Chevron USA Inc. By-Passed/Completed 4.9 miles/NE 

GC 640 IS002 Chevron USA Inc. Completed Water 

Injector Well 5.4 miles/NE 

GC 640 IS003 Chevron USA Inc. Application for Permit to 

Drill 5.4 miles/NE 

GC 640 IS004 Chevron USA Inc. Application for Permit to 

Drill 5.4 miles/NE 

Several pipelines and associated umbilicals are present throughout the area of 3-D seismic data coverage. 

Two 12-inch proposed oil pipelines and a 5-inch proposed umbilical generally trend northeast-southwest

across the central portion of GC 727 which connect the Proposed Wellsite GC 727-2 and the GC 683 #1 well 

with Anadarko’s Constitution Development in GC 680. Two proposed 9-inch pipelines, a proposed 6-inch 

pipeline, and two proposed 6-inch umbilicals trend southwest-northeast which connects Chevron’s 

Production Drill Center South in GC 640 to the Tahiti Spar in GC 641. BP Exploration and Production, 

Inc.’s 2-inch fiber optic cable (Segment No. 17364), trends northeast-southwest, approximately 4.9 miles 

south of the proposed location. A 2-inch, north-south trending branch (Segment No. 17847) of the BP fiber 

optic cable extends north of the primary cable route, approximately 4.6 miles southeast of the proposed 

wellsite (BOEMRE, 2011b). 

Wellsite Conditions 

The surface location is clear of any constraining geologic conditions within a 2,000 ft radius circle from the 

proposed location. 
Project No. 0711-1949 

- 4 - Wellsite GC 727-2

Water Depth and Seafloor Conditions. Seafloor conditions are favorable for exploration drilling at the 

proposed wellsite location. The water depth at the proposed location is about -4,484 ft (Map GC727-2-1). 

The Proposed Wellsite GC 727-2 lies along an expansive shallow salt ridge approximately 3,800 ft east of 

Ship Basin. The seafloor in this area is irregular as a result of the numerous fault scarps and the deformation 

of the shallow overburden by the underlying salt (Map GC727-2-2). The seafloor generally dips toward the 

west-southwest at about 0.7°. The near-surface sediments are expected to be normally consolidated clays 

forming a drape over the area. 

Deepwater Benthic Communities. There is no indication of fluids or gas venting from nearby faults at the 

seabed. Features or areas that could support high-density deepwater benthic communities are not located 

within 2,000 ft of the proposed location. The Seafloor Amplitude Rendering (Map GC727-2-3) shows 

normal or ambient amplitudes along the seabed at, and near, the proposed wellsite. 

The closest area of possible seepage is approximately 3,000 ft north-northeast of the proposed wellsite 

(Maps GC727-2-3 and GC727-2-4). There is a potential for deepwater benthic communities surrounding this 

area. 

Stratigraphy. Stratigraphic conditions are shown on Figures GC727-2-1 and GC727-2-2. The seafloor and 

near surface sediments at the Proposed Wellsite GC 727-2 are expected to be hemipelagic and pelagic clays 

and silty clays. The stratigraphic section between the seafloor and the Top of Salt is approximately 637 ft 

thick. The section above the Top of Salt is folded and highly fractured. In general, the sediments between 

the seafloor and 343 ft below mudline (bml), consists of hemipelagic silts, clays and mud-rich, 

mass-transport deposits. Sediments below 343 ft bml (-4,852 ft bss, below sea surface) to the Top of Salt at 

about 637 ft bml (-5,147 bsl) are likely composed of stiff, overconsolidated clays and clay-rich turbidites. 

Alternating sand, silt, and clay layers are possible within this unit. 

Faults. No seafloor faults are expected to be penetrated by the Proposed Wellsite GC 727-2; however, there 

are several faults near the proposed surface location (Figures GC727-2-1 and GC727-2-2). The closest 

seafloor fault to the proposed wellsite is approximately 1,000 ft to the northeast. The fault trends northeastsouthwest and is downthrown to the southeast. 

No distinct faults were mapped at the Proposed Wellsite GC 727-2; however, the stratigraphic unit above the 

Top of Salt is likely to be highly fractured as a result of the past motion of the underlying shallow salt 

structure. Other faults are likely to exist that are beyond the resolution of the data. 

Shallow Gas and Shallow Water Flow. Significant shallow gas is not expected at this wellsite within the 

upper 637 ft of sediment (Figures GC727-2-1 and GC727-2-2). The potential for shallow water flow at this 

well location is considered negligible (Figure GC727-2-2). 

Shallow Gas. The potential for encountering shallow gas at the Proposed Wellsite GC 727-2 ranges 

from negligible to low. The well path will not penetrate any high-amplitude events between the seafloor and 

the Top of Salt (637 ft bml), Map GC727-2-4 and Figure GC727-2-2. A low potential for encountering 

shallow gas exists from 343 ft bml to the Top of Salt (637 ft bml). An increase in amplitude character in 

places may indicate an increase in minor amounts of gas within possible thin sand layers within this interval. 

There is a negligible potential for encountering shallow gas between the seafloor and 343 ft bml. 

Water flow. There is a negligible potential for shallow water flow within the sedimentary section from 

the seafloor to the Top of Salt (637 ft bml), Figure GC727-2-2. Any thin sand or silty-sand layers 

encountered are not expected to be overpressured. Additionally, the potential for an overpressured 

environment is considerably reduced by faulting and the thin overburden above the shallow salt. 
Project No. 0711-1949 

- 5 - Wellsite GC 727-2

Closing

The Proposed Exploration Wellsite GC 727-2 in Green Canyon Block 683 appears suitable for exploration 

drilling operations. The potential for encountering thin sand layers increases between 343 ft bml and the 

Top of Salt (637 ft bml), but we do not anticipate any significant overpressures associated with this interval. 

In addition, caution is advised as drilling activities must avoid existing infrastructure within close proximity 

of the proposed location. 

We appreciate the opportunity to be of service to Anadarko Petroleum Corporation, and look forward to 

working with Anadarko on future projects. 

Sincerely, 

GEOSCIENCE EARTH & MARINE 

SERVICES, INC. ®

Carla Cleveland 

Associate Geoscientist 

Erin Williams Janes Daniel L. Lanier 

Project Manager - Senior Geoscientist Vice President – Geoscience 

Attachments (4 Maps and 2 Figures) 

Distribution: Mr. Todd A. Fowler, Anadarko Petroleum Corporation (6 Copies) 
Project No. 0711-1949 

- 6 - Wellsite GC 727-2

REFERENCES 

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011a, Pre-seabed disturbance survey mitigation, 

released by BOEMRE in March 2011. 

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011b, Free ASCII Data Files, published on the 

BOEMRE Gulf of Mexico Region Homepage, http://www.gomr.boemre.gov/homepg/pubinfo/freeasci/freedesc.html, 

Accessed July, 2011. 

Coffeen, J. A., 1978, Seismic Exploration Fundamentals: Tulsa, the Petroleum Publishing Co., p. 125. 

Geoscience Earth & Marine Services, Inc. (GEMS), 2003, Geologic and Stratigraphic Assessment Block 683, Green 

Canyon Area, Gulf of Mexico, Project No. 0103-615. Report submitted to Shell Exploration and Production Company. 

Minerals Management Service, 2008a, Notice to lessees and operators of federal oil, gas, and sulphur leases and pipeline 

right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, Shallow hazards requirements: U. S. 

Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G05. 

Minerals Management Service, 2008b, Notice to lessees and operators of federal oil, gas, and sulphur leases in the outer 

continental shelf, Gulf of Mexico OCS region, Information Requirements for Exploration Plans and Development 

Operations Coordination Documents, U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, 

NTL 2008-G04. 

Minerals Management Service, 2008c, Notice to lessees and operators of federal oil, gas, and sulphur leases in the outer 

continental shelf, Gulf of Mexico OCS region, Remotely operated vehicle surveys in deepwater: U. S. Department of the 

Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G06. 

Minerals Management Service, 2008d, Notice to lessees and operators (NTL) of federal oil and gas leases and pipeline 

right-of-way (ROW) holders on the outer continental shelf (OCS), Gulf of Mexico OCS region (GOMR), Revisions to 

the list of OCS lease blocks requiring archaeological resource surveys and reports: U. S. Department of the Interior, 

Minerals Management Service, Gulf of Mexico, NTL 2008-G20. 

Minerals Management Service, 2010, Notice to lessees and operators of federal oil and gas leases in the outer continental 

shelf, Gulf of Mexico OCS region, Deepwater benthic communities: U. S. Department of the Interior, Minerals 

Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27, 2010. 
2175.0

4587.0

2250.0

4587.0

2325.0

4587.0

2400.0

4587.0

2475.0

4587.0

2550.0

4587.0

35000 37500 40000 42500 45000 47500 50000 52500 55000 57500 60000

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

2.600

2.700

2.800

2.900

3.000

3.100

3.200

3.300

3.400

2361.0

4425.0

2361.0

4500.0

2361.0

4575.0

2361.0

4650.0

2361.0

4725.0

2361.0

4800.0

32500 35000 37500 40000 42500 45000 47500

1.700

1.800

1.900

2.000

2.100

2.200

2.300

2.400

2.500

2.600

2.700

2.800

2.900

3.000

3.100

3.200

3.300

3.400

Line:

Trace:

Horizontal

Distance (ft):

Line:

Trace:

Horizontal

Distance (ft):

REL I E MPLI U AT V A T DE REL I E MPLI U AT V A T DE PEAK

TROUGH

Project No. 0711-1949 Filename: 11949_fig_GC 727-2_1.cdr

NORTH SOUTH

Figure GC 727-2-1. Portion of Inline 2361 and Crossline 4587 Showing Conditions 

 Beneath Proposed Wellsite GC 727-2 

WEST EAST

Inline 2361

Crossline 4587 TWO-WAY TRAVEL TIME (SEC)

PROPOSED

WELLSITE

GC 727-2

SEAFLOOR

HORIZON B

PROPOSED

WELLSITE

GC 727-2

HORIZON A

HORIZON C

REL I E MPLI U AT V A T DE REL I E MPLI U AT V A T DE PEAK

TROUGH

TWO-WAY TRAVEL TIME (SEC)

GC

684

GC

683

GC

682

TOP

OF

SALT

SALT

SEAFLOOR

HORIZON A

TOP OF 

SALT

GC

727

GC

683

SALT
2361.0

4500.0

2361.04575.0

2361.04650.0

37500 40000 42500

1.7001.8001.9002.0002.1002.2002.3002.4002.5002.6002.7002.8002.9003.0003.1003.2003.3003.400

WATER

FLOW AND

GAS

POTENTIAL

Shallow Water Flow and Gas Potential

HIGH

0 1 2 3

0 = NEGLIGIBLE

1 = LOW2 = MODERATE

3 = HIGH

SEAFLOOR

NEGLIGIBLE

Two-way Travel Time (sec)

Horizon Lithology/Stratigraphy

Figure GC 727-2-2. Tophole Prognosis Chart, Proposed Wellsite GC 727-2, Green Canyon Block 683

Potential Drilling

Constraints

Filename: 11949_fig_GC 727-2_2.cdr Project No. 0711-1949

Water

Flow Gas

3-D Seismic Section Through

Proposed Wellsite GC 727-2

X = 2,352,025.5 ft; Y = 9,900,518.6 ft

 Inline 2361 at Crossline 4587

W E

TWT

(sec, bml)

Depth

(ft, bml)

Depth

(ft, bss)

Inline 2361

-4,484

-4,852 343 0.137

TWT

(sec, bss)

1.845

1.982

The seafloor slopes to the west-southwest at 0.7o. There is a negligible potential for high-density deepwater benthic communities within 2,000 ft of the surface location.

~HORIZON A

PROPOSED

WELLSITE

GC 727-2

RELATIVE AMPLITUDE

Peak Trough

Line:

Trace:

Horizontal

Distance (ft):

TOP OF SALT -5,147 637 0.246 2.091

Negligible potential for shallow gas and overpressured sands. Hemipelagic silts and clays with thin mud-rich, mass-transport deposits.

Discontinuous, fractured bedding. Predominantlyhard clays and silts interlayered with thin sands.

Low potential for shallow gas. Negligible potential for overpressured sands. 




 

D 

HYDROGEN SULFIDE INFORMATION 

The proposed GC 727-2 well will penetrate and test stratigraphic sections in both GC 683 and 

GC 727. The supra-salt section has previously been penetrated by the Kerr McGee GC 683-1 

(API # 608114042700) approximately 186’ SE of the proposed well and had no recorded 

amounts of Hydrogen Sulfide. The sub-salt section has been penetrated by five additional wells 

in GC 683 including the aforementioned KM GC 683-1, five wells in GC 726 located 

approximately 2.6 miles SSW, including the Anadarko GC 726-1 ST1 (API # 608114049504), 

and the Chevron GC 727-1 (API # 608114037200) located approximately 2 miles to the SSE. 

None of these penetrations encountered any Hydrogen Sulfide within the supra or sub-salt 

section. Since no (H2S) was encountered in any of these wells we request the area be classified 

as a "zone where the absence of H2s has been confirmed.”
 

E 

 BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION 

(a) Chemosynthetic Communities Report 

The seafloor disturbing activities proposed in this plan are in approximately 4,484’ of water. The well 

will be drilled with a DP Drillship or DP Semisubmersible drilling unit. 

Maps 

A map prepared using 3-D seismic data to depict bathymetry, seafloor and shallow geological features, 

surface locations of the proposed wells, and positions of anchors and chains relative to the proposed 

operations is included in Section A. 

Analysis 

Features or areas that could support high-density chemosynthetic communities are not located within 

2000 feet of the proposed muds and cuttings discharge location. 

Features or areas that could support high-density chemosynthetic communities are not located within 250 

feet of any seafloor disturbances. 

(b) Topographic Features Map 

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

an identified topographic feature. Therefore, no map is required per NTL No. 2008-G04. 

(c) Topographic Features Statement (Shunting) 

Anadarko does not plan to drill more than two wells from the same surface location within the Protective 

Zone of an identified topographic feature. Therefore, the topographic features statement required by NTL 

No. 2008-G04 is not applicable. 

(d) Live Bottoms (Pinnacle Trend) Map 

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

relief equal to or greater than 8 feet. Therefore, no map is required per NTL No. 2008-G04. 

(e) Live Bottoms (Low Relief) Map 

The activities proposed in this plan are not within 100 feet of any live bottom low relief features. 

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

(f) Potentially Sensitive Biological Features 

The activities proposed in this plan are not within 200 feet of any potentially sensitive biological features. 

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

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

Green Canyon Blocks 683 and 727 are located within Deepwater Grid Area 10. This grid is considered to 

have “adequate ROV survey coverage”, and therefore, under the guidance set out in NTL No. 2008-G06, 

a Remotely Operated Vehicle Monitoring Survey Plan is not required. 

(h) Threatened and Endangered Species Information 

Under Section 7 of the Endangered Species Act (ESA) all federal agencies must ensure that any actions 

they authorize, fund, or carry out are not likely to jeopardize the continued existence of a listed species, or 

destroy or adversely modify its designated critical habitat. 

In accordance with the 30 CFR 250, Subpart B, effective May 14, 2007, and further outlined in Notice to 

Lessees (NTL) 2008-G04, lessees/operators are required to address site-specific information on the 

presence of federally listed threatened or endangered species and critical habitat designated under the 

ESA and marine mammals protected under the Marine Mammal Protection Act (MMPA) in the area of 

proposes activities under this plan. 

Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer 

Continental Shelf; however, it is possible that one or more of these species could be seen in the area of 

our operations. The following table reflects the Federally-listed endangered and threatened species in the 

lease area and along the northern Gulf coast: 

Species Scientific Name Status 

Potential Presence Critical Habitat 

Designated in 

Gulf of Mexico 

Lease 

Area Coastal 

Marine Mammals 

Sperm whale Physeter macrocephalus E X -- None

Florida manatee Trichechus manatus 

latirostris E -- X Florida 

(Peninsular)

Blue whale Balaenoptera musculus E Xa -- None

Fin whale Balaenoptera physalus E Xa -- None

Humpback whale Megaptera novaeangliae E Xa -- None

North Atlantic right whale Eubalaena glacialis E Xa -- None

Sei whale Balaenoptera borealis E Xa -- None

Sea Turtles 

Loggerhead turtle Caretta caretta T X X None

Green turtle Chelonia mydas T, Eb X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys imbricata E X X None

Kemp’s ridley turtle Lepidochelys kempii E X X None

Birds 

Piping Plover Charadrius melodus T -- X 

Coastal Texas, 

Louisiana, Mississippi, 

Alabama, and Florida 

(Panhandle) 

Whooping Crane Grus americana E -- X 

Coastal Texas 

(Aransas National 

Wildlife Refuge)

Fishes 

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X 

Coastal Louisiana, 

Mississippi, Alabama, 

and Florida (Panhandle)

Terrestrial Mammals 

Beach mice (Alabama, 

Choctawhatchee, Perdido 

Key, St. Andrew)

Peromyscus polionotus E -- X Alabama and Florida 

(Panhandle) beaches 

Abbreviations:  E = Endangered; T = Threatened.   a

   The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are

unlikely to be present in the lease area.
 

b

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

The Environmental Impact Analysis in Section N of this plan further discusses potential impacts 

and mitigation measures related to threatened and endangered species. 

(i) Archaeological Report 

Green Canyon Blocks 683 and 727 are not located in an area designated as an area of high 

archaeological potential and, as such, an Archaeological Report is not required per NTL No. 

2008-G04. However, per new BOEMRE guidelines concerning the potential damage to 

archaeological resources by bottom disturbing activities (BOEMRE 2011), Anadarko has 

submitted a copy of the Archeological Assessment conducted by Fugro Geoservices, Inc with 

this plan. The survey was conducted in accordance with the latest guidelines established by the 

BOEMRE in 2011. 

(j) Air and Water Quality Information

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

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

(k) Socioeconomic Information 

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

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

F 

WASTE AND DISCHARGE INFORMATION 

The following estimates were prepared utilizing Anadarko’s experience with similar drilling operations. 

Estimated maximum discharge rates are reflected below. 

(a) Projected Generated Wastes 

Type of Waste Composition Projected Amount Treatment/Storage/Disposal 

Synthetic-based 

drilling fluids 

Synthetic-based 

drilling muds 

14,000 bbls/well Re-use and/or transport to shore in 

tanks to Fourchon, Louisiana and 

on to base/transfer station. If 

recycled, returned to vendor (Bariod 

or MI).

Cuttings wetted 

with syntheticbased fluids 

Cuttings coated with 

synthetic drilling 

muds/fluids, 

including drilled out 

cement 

8,000 bbls/well Treated and discharge overboard 

*Note, an estimated 5-10% of cuttings 

may be transported to shore in tanks 

and/or cutting boxes and on to the 

base/transfer station if oil still 

remains. 

Water-based 

drilling fluids 

Water based drilling 

muds (NaCl 

saturated, seawater, 

freshwater, barite) 

50,000 bbls/well Discharge overboard or at seafloor 

Cuttings wetted 

with water-based 

fluids 

Cuttings coated with 

water-based drilling 

muds/fluids 

24,000 bbls/well Discharge overboard 

Chemical product 

waste (well 

treatment fluids) 

Ethylene glycol 

Methanol 

100 bbls/month 

25 bbls/month 

Transport to shore in barrels to 

Fourchon, Louisiana for pick up. 

Completion Fluids Brine, spent acid, 

prop sand, debris 

3,000 bbls per well Transport to shore in barrels to 

Fourchon, Louisiana and on to 

Newpark Base. 

Non-pollutant 

completion fluids 

Low density 

uninhibited 

completion brines 

5,000 bbls/well Discharge overboard 

Workover fluids Brine, spent acid, 

prop sand, debris 

3,000 bbls per well Transport to shore in barrels to 

Fourchon, Louisiana and on to 

Newpark Base. 

Trash Refuse generated 

during operations 

50 bbls/month Transport to shore in disposal bags 

by vessel to shorebase for pickup 

by municipal operations. 

*Sanitary Wastes Treated human body 

waste 

300,000/gals/well Chlorinate and discharge 

overboard 

*Domestic Waste Gray water 300,000/gals/well Chlorinate and discharge 

overboard 

Deck drainage Platform washings 

and rainwater 

210,000/bbls/well Treat for oil and grease and 

discharge overboard 

Produced water N/A N/A N/A 

Desalinization Unit Seawater 21,000/bbl/well Discharge overboard 

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

Blowout preventer 

fluid 

Blend (3% Stack 

Magic & Filtered 

Fresh Water) 

925 gals/week/well Discharge at seafloor 
 

Ballast water Seawater As needed Discharge overboard 

Bilge water Seawater 685 bbls/well Discharge overboard through 15 

ppm equipment 

Excess cement at 

the seafloor 

Nitrified cement 

slurry 

1,200 bbls/well Discharge at seafloor 

Fire water Seawater 137,142 bbls/day Discharge overboard 

Cooling water Seawater 137,142 bbls/day Discharge overboard 

Produced Sand N/A N/A N/A 

Used oil Excess oil from 

engines 

645 bbls/well Transport in totes to shore for 

recycling. 

(b) Projected Ocean Discharges

Type of Waste Total Amount to 

be Discharged 

Discharge Rate Discharge Method 

*Sanitary Wastes 300,000/gals/well 25 gals per person 

daily 

Chlorinate and discharge 

overboard 

*Domestic waste 300,000/gals/well 25 gals per person 

daily 

Chlorinate and discharge 

overboard 

Deck drainage 210,000/bbls/well 3500 bbls/day Treat for oil and grease and 

discharge 

Blowout preventer fluid 925 gals/week/well Vents on weekly 

basis 

Discharge at seafloor 

Desalinization Unit 21,000/bbl/well 350 bbls/day Discharge overboard 

Wash water 3,000 bbl/60 day well 50 bbls/day Discharge overboard 

Ballast water As needed Not continuous Discharge overboard 

Bilge water 685 bbls/well 317 bbls/day Discharge overboard through 15 

ppm equipment 

Excess cement at the 

seafloor 

1,200 bbls/well 20 bbls/min Discharge at seafloor 

Fire water 137,142 bbls/day NA Discharge overboard 

Cooling water 137,142 bbls/day NA Discharge overboard 

Cuttings wetted with 

Water-based fluids 

24,000 bbls/well 1,000 bbls/hr max Discharge overboard 

Water-based drilling 

fluids 

50,000 bbls/well 1,000 bbls/hr max Discharge at seafloor or 

overboard 

Cuttings wetted with 

Synthetic-based fluids 

8,000 bbls/well NA Treated and discharge overboard 

*Note, an estimated 5-10% of 

cuttings may be transported to shore 

in tanks and/or cutting boxes and on 

to the base/transfer station if oil still 

remains.

Non-pollutant 

completion fluids 

5000 bbl/well 100 bbl/hour Discharge overboard 

*The rig is designed for maximum personnel capacity of 200 people. The discharge rates are based off of maximum personnel 

capacity but will generally not have this many personnel onboard during drilling and/or completion operations. 

(c) Modeling Report 

The proposed activities under this plan do not meet the U.S. Environmental Protection Agency 

requirements for an individual NPDES permit. Therefore, modeling report requirements per 

NTL No. 2008-G04 is not applicable to this EP. 
 

G 

AIR EMISSIONS INFORMATION 

(a) Screening Questions 

Screening Questions for EP’s Yes No

Is any calculated Complex Total (CT) Emission amount (in tons) associated with your 

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

following formulas: CT = 3400D2/3 for CO, and CT = 33.3D for the other air pollutants 

(where D = distance to shore in miles)? 

 No 

Do your emission calculations include any emission reduction measures or modified 

emission factors? 

 No 

Are your proposed exploration activities located east of 87.5 W longitude? No 

Do you expect to encounter H2S at concentrations greater than 20 parts per million (ppm)? No 

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

proposed well? 

 No 

Do you propose to burn produced hydrocarbon liquids? No 

(b) Emissions Worksheets 

Air emissions worksheets have been prepared using a DP Drillship and DP Semisubmersible 

drilling units. Air emissions worksheets are available upon request. Per NTL No. 2008-G04, if 

an operator “answers no to all of the above screening questions from the appropriate table, 

provide”: 

 

 (1) “Summary information regarding the peak year emissions that will be generated by 

and associated with your Plan Emissions and Complex Total Emissions. This information is 

compiled on the summary form of the two sets of worksheets, and you can submit either these 

summary forms or the format below. You do not need to include the entire set of worksheets.” 

(c) Summary Information 

If drilled with a DP Semisubmersible: 

Air Pollutant Plan Emission 

Amounts1

 (tons)

Calculated 

Exemption 

Amounts2

 (tons)

Calculated Complex 

Total Emission 

Amounts3 (tons)

Particulate matter (PM) 93.94 3996.00 N/A 

Sulphur dioxide (SO2) 430.97 3996.00 N/A 

Nitrogen oxides (NOx) 3229.32 3996.00 N/A 

Volatile organic compounds (VOC) 96.88 3996.00 N/A 

Carbon monoxide (CO) 704.58 82717.95 N/A 

If drilled with a DP Drillship: 

Air Pollutant Plan Emission 

Amounts1

 (tons)

Calculated 

Exemption 

Amounts2

 (tons)

Calculated Complex 

Total Emission 

Amounts3 (tons)

Particulate matter (PM) 94.86 3996.00 N/A 

Sulphur dioxide (SO2) 435.16 3996.00 N/A 

Nitrogen oxides (NOx) 3260.72 3996.00 N/A 

Volatile organic compounds (VOC) 97.82 3996.00 N/A 

Carbon monoxide (CO) 711.43 82717.95 N/A 
 

The air emission calculations were calculated by: 

Jill Fowler 

Regulatory Analyst 

(832) 636-1554 

jill.fowler@anadarko.com 

 
 

H 

OIL SPILL INFORMATION 

(a) Oil Spill Response Planning 

(i) OSRP Information 

All the proposed activities and facilities in this EP are covered by the Regional Oil Spill 

Response Plan (OSRP) approved on June 24, 2009 and the Oil Spill Response Certification letter 

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

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

Numbers 00981, 02219 and 00148, respectively) in accordance with 30 CFR Part 254. Anadarko 

submitted a revision to its Regional OSRP on July 21, 2011 updating the exploratory WCD to 

Garden Banks Block 346. The revision is pending approval. 

(ii) Spill Response Sites 

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

Harvey, Louisiana 

Venice, Louisiana 

Lake Charles, Louisiana 

Leeville, Louisiana 

Morgan City, Louisiana 

Harvey, Louisiana 

Venice, Louisiana 

Cameron, Louisiana 

Leeville, Louisiana 

Morgan City, Louisiana 

(iii) OSRO Information 

Anadarko’s primary equipment provider is Clean Gulf Associates (CGA). Personnel would be 

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

supervisor to operate the equipment. 

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

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

personnel and additional equipment as needed. 

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

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

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

Anadarko is also a member of the Marine Well Containment Company (MWCC), which 

provides access to containment response capabilities and includes subsea dispersant injection 

equipment. 
 

(iv) Worst-Case Scenario Determination 

Category Regional OSRP EP 

Type of Activity Exploratory Exploratory 

Facility Location GB 346 GC 727 

Facility Designation * GB 346 “A” GC 727 #002 

Distance to Nearest 118 miles 120 miles 

 Storage Tanks (total) N/A N/A 

 Flowlines (on facility) N/A N/A 

 Pipelines N/A N/A 

 Uncontrolled Blowout 350,000 bopd** 340,281 bopd 

Type of Oil(s) Oil Oil 

API Gravity 30.1o 28.9o

* Note–for the OSRP exploratory worst case discharge scenario only the Area/Block is referenced in the OSRP. Exploratory drilling facility 

designations (proposed well location names) are typically not included in the OSRP. 

** The volume denoted in the Regional OSRP is higher than the NTL No. 2010-N06 (256,700 bopd) and BOEMRE (321,108 

bopd) calculations. Anadarko elected to denote a higher volume in the Regional OSRP for planning purposes to 

demonstrate equipment response capabilities per previous discussions with Rusty Wright. 

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

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

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

Regional OSRP, and since the worst-case scenario determined for our EP does not replace the 

worst-case scenario in our revised Regional OSRP submitted on July 21, 2011, I hereby certify 

that Anadarko has the capability to respond, to the maximum extent practicable, to a worst-case 

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

EP. 

(b) Worst-Case Discharge Volume Assumptions 

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

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

WCD scenario and assumptions for Green Canyon Block 727: 

Discussions regarding geologic information are considered proprietary and have been omitted 

from this public copy EP. 

(c) Oil Spill Response Discussion

For the purpose of NEPA analysis, the largest spill volume originating from the proposed 

activity would be an uncontrolled blowout of the well during drilling operations at 340,281 

BOPD with an API gravity of 28.9o

. A discussion of the blowout scenario from this proposed 

activity is included within this Supplemental EP in accordance with NTL No. 2010-N06. 
 

Land Segment and Resource Identification Modeling

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

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

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

Contingency Planning Statistics for Gulf of Mexico OCS Activities” (OCS Report MMS 2004-

026), using the average conditional probability for 3, 10, and 30 day impacts. 

Green Canyon Blocks 727 is located within Launch Area 46. According to the BOEMRE 

OSRAM, the trajectory indicates a 3% probability of potential impact to the shoreline in 

Cameron and/or Plaquemines Parish, Louisiana. The results are shown in Table H-2. 

Cameron and/or Plaquemines Parish are identified as the most probable potential impacted parish 

or county within the Gulf of Mexico for this operation. Cameron Parish is located in Louisiana 

and includes Cameron Prairie National Wildlife Refuge (NWR), East Cove Unit (a part of the 

Cameron Prairie NWR), Lacassine NWR, and Sabine NWR. Plaquemines Parish is also located 

in Louisiana and includes Delta NWR, Pass-a-Loutre Wildlife Management Area (WMA), and 

Bohemia State WMA. 

Response 

Anadarko will make every effort to respond to the worst-case discharge as effectively as 

possible. Response equipment available to respond to the worst-case discharge and the estimated 

time of a spill response from oil spill detection to equipment deployment on-site is included in 

Table H-3. The table estimates individual times needed for procurement, load out, travel time to 

the site and deployment. In the event of an actual incident equipment and times can vary. 

For the purpose of response scenario discussion, an uncontrolled blowout of the well would be 

considered the largest potential spill volume at 340,281 BOPD. An ADIOS weathering model 

was run based on a similar type of oil expected to be produced from this well. Based on this 

information, approximately 11% (37,431 bbls) of the initial volume would be 

evaporated/dispersed within 24 hours. 

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

(9,600 gallons) from two DC-3 aircrafts could disperse approximately 7,540 barrels of oil. 

If the conditions are appropriate, and the necessary approvals and permits have been obtained, 

in-situ burning may be utilized. Based on in-situ burn operations during Deepwater Horizon, 

approximately 5% (15,143 bbls) of the total initial worst case discharge could be burned. 

Although unlikely in a spill lasting thirty (30) days, potential shoreline impact in Cameron and/or 

Plaquemines Parish, Louisiana could occur depending on environmental conditions (wind, 

currents and temperature) at the time of an incident. Nearshore response may include the use of 

shoreline boom on beach areas, or protection/sorbent boom on vegetated areas. Surveillance and 

real time trajectories would aide in determining the most appropriate strategies to respond to a 

spill. 
 

Table H.3 provides an example of offshore and nearshore equipment, response times, and 

personnel to respond to a spill of 302,850 bbls, which is the estimated amount that would remain 

considering natural evaporation/dispersion at 24 hours. This amount could be further reduced 

through the application of aerial and subsea dispersants, and in-situ burning provided such 

applications/actions were approved. 

Anadarko’s contingency plan for dealing with this worst-case discharge would be to activate its 

Spill Management Team and equipment resources as described in its Gulf of Mexico Regional 

Oil Spill Response Plan (OSRP) and provide continuous support for the duration of the event. 

Response resources are activated and supplemented according to need. These resources would 

remain engaged in the response until the incident is deemed complete or until released by 

Unified Command. 

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

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

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

Anadarko is also a member of the Marine Well Containment Company (MWCC), which 

provides access to containment response capabilities and includes subsea dispersant injection 

equipment. 

In the event of a blowout, Anadarko may: 

 1. Evacuate personnel, if necessary. Deploy emergency responders in an effort to preserve 

human life, if necessary. 

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

the amount of oil discharged. 

 3. Notify agencies. 

 4. Assess the amount of oil that has been spilled and calculate additional potential of oil 

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

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

water, combined with observations at the source, would be used to provide a constant 

update. Additional potential to release fuel from the remaining tanks onboard the drilling 

rig would be determined by marine surveyors. Operations and Unified Command would 

continue to assess the adequacy of response equipment capacities based on this 

continually updated mass balance. 

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

objectives and priorities. 

 6. Monitor the oil spill with aerial surveillance and obtain trajectories. If oil is seaward 

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

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

request approval to utilize dispersants. 

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

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

are present in the projected application area or otherwise at risk from dispersant 

application. 

 b. Upon approval, mobilize one Basler aircraft and two DC-3 aircrafts from Houma, with 

surveillance aircraft and spotter. Rotate aircraft, spraying the leading edge of the spill 

and working back to the source. Monitor/sample for effectiveness (USCG SMART 

Team). Truck additional dispersants from CGA stockpile to Houma, if necessary. 

 c. Dispersants are most effective when applied as soon after discharge as possible, since 

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

opportunity for most effective use of dispersants is within 48-72 hours post-release. 

The oil may still be dispersible after 72 hours on the water surface, but the 

effectiveness of dispersant use would likely be diminished after the oil has been on the 

water for more than three days. Ultimately, the USCG SMART monitoring protocol 

will be used to determine whether or not dispersant operations are effective. 

 d. Once the CGA HOSS barge is on location and in the skimming mode, dispersants 

would only be used if required and approved. 

 8. Deploy offshore mechanical oil containment and recovery equipment. Attempt to recover 

as much oil at sea as possible, utilizing: 

 a. The CGA HOSS barge, will be positioned in a stationary mode, will be situated downwind and down-current from location for long-duration, high-volume skimming. 

Based on average travel times, the HOSS barge could be on location within 

approximately 31 hours of the release. The de-rated skimming capacity of the HOSS 

barge is 43,000 bbls per day. However, only the oil encountered by a skimmer can be 

recovered. In order to maximize oil encounter rate, boom will be deployed in a 

V-configuration in front of the HOSS barge to funnel oil to the skimmers. If 

necessary, temporary barges can be activated to support continuous skimming 

operations. (These barges arrive on-site at approximately the same time as the HOSS 

barge.) For an on-going release, multiple barges are deployed to provide for 

continuous off-loading of skimmer storage vessels and shuttling of recovered oil to an 

onshore waste handling facility. Sufficient barges are available to provide enough 

temporary storage for continuous recovery operations. 

 b. CGA’s Fast Response Units (FRU) would arrive on-scene between approximately 

17-25 hours of the initial release. These skimmers operate downstream of the HOSS 

barge and are used to recover pockets and streamers of oil that may move past the 

large stationary skimmer. Each FRU has 200 barrels of on-board storage. Approval 
 

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

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

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

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

would typically work daylight hours only. The HOSS barge can operate continuously, 

including night operations. Available technology will be considered such as remote 

sensing devices that will enable 24 hour surveillance, trajectories, and planning. All 

response vessels are designed to be able to remain offshore continuously throughout the 

response. Even if sea conditions prohibit effective skimming, these resources would 

remain offshore until skimming operations could be commenced again. Safety would 

remain the first priority. 

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

Communications and Medical Plans. 

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

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

boom with reference to Area Contingency Plans and in coordination with State and 

Federal On-Scene Coordinators. 

 a. Implement pre-designated strategies. 

 b. Identify resources at risk in spill vicinity. 

 c. Develop/implement appropriate protection tactics. 

 12. Establish Site-Specific Wildlife Rescue and Rehabilitation Plan. 

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

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

operators 

 Vessels for supporting offshore operations 

 Field safety personnel 

 Continued surveillance and monitoring of oil movement 

 Helicopter, video cameras 

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

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

storage barges to onshore disposal sites that are identified in Area Contingency Plans 

(ACP) 

 Logistics needed to support equipment: 

- Staging areas 

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

- Fueling facilities 

- Decontamination stations 
 

- Dispersant stockpile transported from Houston to Houma or other potential 

command post locations 

- Communications equipment and technicians 

 Logistics needed to support responder personnel 

- Medical aid stations 

- Safety personnel

- Food 

- Berthing 

- Additional clothing/safety supplies 

- Decontamination stations 
 

Table H-1 

Worst Case Discharge Calculation 

(Based on Blowout during Drilling Operations)

Calculations for Uncontrolled Blowout> 10 miles from shore: Block 727 

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

 ii. API Gravity 28.9 ̊

 iii. EP Location Used for NTL No. 2010-N06 WCD for GC 727 SEP well “#002” 

 iv. Largest Anticipated WCD Rate during blowout 340,281 BOPD 

 v. WCD Total for Drilling Operations for GC 727 (> 10 miles from shore): 340,281 BOPD 
 

Table H-2 

Trajectory by Land Segment 

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

particular launch area will contact a land segment as included in the BOEMRE Oil Spill Risk Analysis Model 

(OSRAM) for the Central Gulf of Mexico. This information can be found on the BOEMRE website using 3/10/30 

day potential impact, as applicable. The results are listed below. 

Area/Block OCS-G Launch 

Area Land Segment and/or Resource 

Conditional Probability (%) 

3 

days 

10 

days 

30 

days 

Green Canyon 

Blocks 727 

Drilling 

(120 miles from 

shore) 

G16783 LA 46 

Central 

Planning 

Area 

Matagorda County, TX 

Brazoria County, TX 

Galveston County, TX 

Jefferson County, TX 

Cameron Parish, LA 

Vermilion Parish, LA 

Lafourche Parish, LA 

Terrebonne Parish, LA 

Plaquemines Parish, LA 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

1 

1 

2 

1 

3 

1 

1 

1 

3 
Table H-3 

WCD Scenario Drilling Activities – Based on a single well uncontrolled blowout (120 miles from shore) Green Canyon Block 727 340,281 BOPD (initial volume) 302,850 BOPD (after evaporation/dispersion) API Gravity 28.9o 

Offshore Equipment from Spill Detection to Equipment Deployment Response Time: Green Canyon Block 

Offshore Equipment 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Tra

Tim

(Stag

Spi

(3

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

Basler Spray Aircraft DC 3 Spray Aircraft Aero Commander 

-- -- 

-- -- 

1 2 2 

ASI/Houma Houma 

0 0 1 1 1 1 

HOSS Barge Operators Tugs 

43,000 4,000 1 

8 3 

CGA/Harvey STARS VOO 

Harvey 

1 2 4 4 0 26 

OSRB Valiant Operators Tugs 

24,000 20,892 1 

6 1 

NRCC/Aransas Pass ICN VOO 

Aransas Pass 

0 2 2 1 4 40 

OSRB Defender Operators Tugs 

24,000 16,500 1 

6 1 

NRCC/Bayou La Batre ICN VOO 

Bayou La Batre 

0 2 2 1 4 33 

OSRB Energy Operators Tugs 

1,512 300 1 

4 1 

NRCC/Morgan City ICN VOO 

Morgan City 

0 2 2 1 4 17 

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Ingleside STARS VOO 

Ingleside 

0 2 2 1 2 2

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 2 19 

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Lake Charles STARS VOO 

Cameron 

.5 

2 2 1 2 15

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Morgan City STARS VOO 

Morgan City 

.5 

2 2 1 2 14

FRU Operators Utility Boat 

3,770 200 1 

6 1 

CGA/Harvey STARS VOO 

Harvey 

.5 

2 2 1 2 13 

FRU Operators Utility Boat 

7,540 400 2 

12 

2 

CGA/Leeville STARS VOO 

Leeville 

.5 

2 2 1 2 14 

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

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trav

Tim

(Stagi

Spil

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

FRU Operators Utility Boat 

7,540 400 2 

12 

2 

CGA/Venice STARS VOO 

Venice 

0 2 2 1 2 15 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

89,145 2,500 5 sets 

30 

5 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 12 18 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

53,487 1,500 3 sets 

18 

3 

CGA/Leeville STARS VOO 

Leeville 

0 2 2 1 12 14 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

17,829 500 1 set 

6 1 

CGA/Fourchon STARS VOO 

Fourchon 

0 2 2 1 12 13 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

35,658 1,000 2 sets 

12 

2 

CGA/Venice STARS VOO 

Venice 

0 2 2 1 12 14 

DBL 101 Operators Tugs 

-- 107,285 1 

20 

4 

K-Sea/Atlantic Venice 

0 2 4 2 4 41 

DBL 102 Operators Tugs 

-- 107,285 1 

20 

4 

K-Sea/Atlantic Venice 

0 2 4 2 4 41 

CTCo 2605 Operators Tug 

-- 20,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 25 

CTCo 5001 Operators Tug 

-- 47,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 25 

10,000' 42" Auto Boom VOO 

-- -- 40 

20 crew 

CGA/Harvey STARS Harvey .5 2 1 2 13 

5,000' 42" Auto Boom VOO 

-- -- 20 

10 crew 

CGA/Lake Charles STARS Cameron .5 2 1 2 15.5 

5,000' 42" Auto Boom VOO 

-- -- 20 

10 crew 

CGA/Galveston STARS Galveston 0 2 1 2 19 

2,500' 42" Auto Boom VOO 

-- -- 12 

6 crew 

CGA/Ingleside STARS Ingleside 0 2 1 2 21 

2,500' 42" Auto Boom VOO 

-- -- 12 

6 crew 

CGA/Pascagoula STARS Pascagoula 0 2 1 2 16 

2,700' 42" Boom VOO 

-- -- 12 

6 crew 

NRCC/Aransas Pass ICN Aransas Pass 0 2 1 2 22 

4,000' 42" Boom VOO 

-- -- 16 

8 crew 

NRCC/Corpus Christi ICN Corpus Christi 0 2 1 2 22..

1,000' 42" Boom VOO 

-- -- 6 

3 crew 

NRCC/Bayou La Batre ICN Bayou La Batre 0 2 1 2 19 

300' 42" Boom VOO 

-- -- 2 

1 crew 

NRCC/Morgan City ICN Morgan City 0 2 1 2 14 
Offshore Equipment, cont. 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trav

Tim

(Stagi

Spil

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

22,400' 42" Boom VOO 

-- -- 80 

25 crew AMPOL/New Iberia New Iberia 0 2 1 2 17 

4,800' 42" Boom VOO 

-- -- 18 

9 crew AMPOL/Harvey Harvey 0 2 1 2 13 

Spotter Helo Surveillance Helo Hand Held Radios 

-- -- -- 

-- -- -- 

1 1 

30 

PHI/Fourchon PHI/Fourchon STARS 

Spill Site Spill Site Fourchon 

1 1 

1.5 

1 1 

1.5 

-- -- -- 

2 2 2 

Total 322,561 330,562 
Nearshore Equipment from Spill Detection to Equipment Deployment Response Time: Green Canyon Bloc

Nearshore Equipment* 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trave

Time 

(Stagin

Spill) 

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

Basler Spray Aircraft DC 3 Spray Aircraft Aero Commander 

-- -- 1 

2 2 

ASI/Houma Houma 

0 0 1 1 1 1 

OSRV Admiral Operators 

24,000 300 1 

6 

NRCC/Galveston ICN Galveston 0 2 1 2 12 

OSRV Liberty Operators 

24,000 300 1 

6 

NRCC/Miami ICN Miami 0 2 1 4 29 

SWS Egmopol Operators 

3,000 100 1 

3 

CGA/Galveston STARS Galveston 0 2 1 2 10 

SWS Egmopol Operators 

3,000 100 1 

3 

CGA/Morgan City STARS Morgan City .5 2 1 2 12 

SWS Marco Operators 

3,588 34 1 

3 

CGA/Leeville STARS Leeville .5 2 1 2 11 

SWS Marco Operators 

3,588 20 1 

3 

CGA/Lake Charles STARS Cameron .5 2 1 2 8 

SWS Marco Operators 

3,588 34 1 

3 

CGA/Venice STARS Venice .5 2 1 2 10 

56' Nearshore Skimmer Operators 

21,500 250 1 

4 

CGA/Morgan City STARS Morgan City .5 2 1 2 13 

R/V Grand Bay Operators 

5,000 65 1 

3 

CGA/Venice STARS Venice .5 2 2 .5 8 

R/V RW Armstrong Operators 

5,000 65 1 

3 

CGA/Leeville STARS Leeville .5 2 2 .5 7 

R/V Bastian Bay Operators 

5,000 65 1 

3 

CGA/Lake Charles STARS Cameron .5 2 2 .5 11.5 

R/V Timbalier Bay Operators 

5,000 65 1 

3 

CGA/Galveston STARS Galveston 0 2 2 .5 12 

CTCo2603 Operators Tug 

-- 25,000 1 

6 1 

EMS/Amelia Amelia

0 2 4 4 0 20 

CTCo 2604 Operators Tugs 

-- 20,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 20 

CTCo 2606 Operators Tugs 

-- 20,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 20 

CTCo 2607 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 20 

CTCo 2608 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 20 
Nearshore Equipment, cont.* 

Owner/Location Initial Staging 

Hours to 

Staging 

Area 

Time to 

Procure 

(1) 

Time 

to 

Load Out 

(2) 

Trave

Time 

(Stagin

Spill) 

(3) 

Type 

Derated 

Capacity 

(bbls) 

Storage 

(bbls) 

No. of 

Units/ 

Persons 

CTCo 2609 Operators Tugs 

-- 23,000 1 

6 1 

EMS/Amelia Amelia 

0 2 4 4 0 20 

8-Band Rope Mop Utility Boat 

2,283 100 1/4 

1 

NRCC/Galveston VOO Galveston 0 2 1 2 8 

4-Band Rope Mop Utility Boat 

1,509 100 1/4 

1 

NRCC/Morgan City VOO Morgan City 0 2 1 2 5 

Vikoma Cascade Utility Boat 

5,520 100 1/4 

1 

NRCC/Houston VOO Galveston 0 2 1 2 8.75 

Vikoma Cascade Utility Boat 

5,520 100 1/4 

1 

NRCC/Sulphur VOO Sulphur 0 2 1 2 6 

2,000' Beach Boom -- -- 6 CGA/Galveston Galveston 0 1 2 8 1,000' Beach Boom -- -- 4 CGA/Ingleside Ingleside 0 1 2 10 2,000' Beach Boom -- -- 6 CGA/Pascagoula Pascagoula 0 1 2 6 10,000' 18" Boom VOO 

-- -- 10/4 

1 Oil Mop/New Iberia New Iberia 0 2 1 1 4.5 

10,000' 18" Boom VOO 

-- -- 10/4 

1 Oil Mop/Houston Houston 1 2 1 1 8.75 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Port Arthur Port Arthur 0 2 1 1 7.25 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Houma Fourchon .5 2 1 1 3.5 

10,000' 18" Boom VOO 

-- -- 10 

4 crew Oil Mop/Port Allen Port Allen 0 2 1 1 4.5 

20,000' 18" Boom VOO 

-- -- 20 

8 crew Oil Mop/Belle Chasse Venice .5 2 1 1 3 

15,000' 18" Boom VOO 

-- -- 14 

6 crew Oil Mop/Gretna Gretna 0 2 1 1 4 

Wildlife Support Trailer -- -- 1/ 2 crew CGA/Harvey Harvey .5 1 2 3 Bird Scare Cannons -- -- 2 CGA/Venice Venice .5 1 2 3.25 Bird Scare Cannons -- -- 1 CGA/Galveston Galveston .5 1 2 8.25 Bird Scare Cannons -- -- 1 CGA/Ingleside Ingleside .5 1 2 10 Bird Scare Cannons -- -- 2 CGA/Lake Charles Cameron .5 1 2 5.25 Bird Scare Cannons -- -- 2 CGA/Pascagoula Pascagoula .5 1 2 5 Bird Scare Cannons -- -- 2 CGA/Harvey Harvey .5 1 2 4 Spotter Helo Surveillance Helo Hand Held Radios 

-- -- -- 

-- -- -- 

1 1 

30 

PHI/Houma PHI/Houma STARS 

Spill Site Spill Site Fourchon 

1 1 

1.5 

1 1 

1.5 

-- -- -- 

1.5 1.5 

2 

Total 121,096 135,798 

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

H-3 (continued) 

Operational Limitations of Response Equipment 

 HOSS Barge–8 foot seas 

 Fast Response Unit (FRU)–8 foot seas 

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

 Boom–3 foot seas, 20 knot winds 

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

1,000 feet 
 

I 

Environmental Monitoring and Environmental Mitigation Measures 

(a) Monitoring 

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

Anadarko subscribes to Wilkins Weather Service which provides real-time weather 

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

(b) Incidental Takes 

Although marine mammals may be seen in the area, Anadarko does not believe that its 

operations proposed under this EP will result in the harassment, capture, collection or 

killing of any mammals covered by the Marine Mammal Protection Act. 

Anadarko will operate in accordance with applicable regulations, including: 

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

Protected Species Observer Program” 

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

NTL No. 2007-G04 “Vessel Strike Avoidance and Injured/Dead Protected Species 

Reporting” 
 

J 

LEASE STIPULATIONS INFORMATION 

Lease Sale # 166: 

Military Area: Green Canyon Block 683 is located within Military Warning Area W-92. 

Anadarko will contact the Naval Air Station, Air Operations Department, New Orleans, 

Louisiana in order to coordinate and control the electromagnetic emissions during these 

proposed operations. 

Lease Sale # 157: 

Military Area: Green Canyon Block 727 is located within Military Warning Area W-92. 

Anadarko will contact the Naval Air Station, Air Operations Department, New Orleans, 

Louisiana in order to coordinate and control the electromagnetic emissions during these 

proposed operations. 
 

K 

Support Vessels and Aircraft Information 

(a) General 

Type Max. Fuel Tank 

Storage Capacity 

Max. No. in Area at 

any Time 

Trip Frequency or 

Duration 

Supply Vessel 3500 gallons 1 2 trips/week 

Helicopter 280 gallons 1 7 trips/week 

Crew Vessel 1500 gallons 1 3 trips/week 

Tug Boat N/A N/A N/A 

(b) Diesel Oil Supply Vessels 

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

a. Size of fuel supply vessel: 230 feet 

b. Carrying capacity of fuel supply vessel: 309,270 gallons 

c. Frequency that fuel supply vessel will visit the 

facilities: once per week 

d. Routes the fuel supply vessel will use to travel 

between the onshore support base and proposed 

facility: 

6 miles from Port Fourchon to the mouth of 

Bayou Lafourche, then approximately 125 

miles to GC 683/727. 

(c) Vicinity Map 

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

(d) Solid and Liquid Wastes Transportation 

Type of 

Waste 

Composition Total 

Projected 

Amount 

Rate Transport 

Method 

Name/Location of 

Facility 

Disposal 

Method 

Syntheticbased drilling 

fluid or mud 

Synthetic- based 

drilling muds 

14,000 bbls 14,000 

bbls/well 

Re-use 

and/or 

transport to 

shore in 

tanks. 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Station Port Arthur. USLL 

Galveston and Fourchon 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 

dipsosal facility) or 

USLL (landfarm). 

Cuttings 

wetted with 

syntheticbased muds 

Cuttings coated 

with synthetic 

drilling muds, 

including drilled 

out cement 

400-800 bbls 400-800 

bbls/well* 

*An 

estimated 

5-10% of 

Re-use 

and/or 

transport to 

shore in 

tanks and/or 

cutting 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 
 

cuttings may 

be 

transported 

to shore 

boxes. Station Port Arthur. USLL 

Galveston and Fourchon 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

disposal facility) or 

USLL (landfarm). 

Chemical 

product 

waste (well 

treatment 

fluids) 

Ethylene glycol 

Methanol 

600 bbls 

150 bbls 

100 

bbls/month 

25 

bbls/month 

Transport 

to shore in 

drums 

and/or tote 

tanks for 

pick up 

Chemwaste in Sulphur, 

LA and Veolia Port 

Arthur, TX or to 

Newpark, Port Arthur 

as non-hazardous waste. 

Can be returned 

to vendor and/or 

used at another 

facility; MEG is 

solidified and 

disposed of in a 

landfill. 

Methanol is 

incinerated or 

used for fuels 

blending. 

Completion 

fluids 

Brine, spent 

acid, prop 

sand, debris 

3,000 bbls 3,000 

bbls/well 

Transport 

to shore in 

cuttings 

boxes, 

drums, 

and/or 

vessel tanks 

for pick up 

Sent to Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer 

Station #1 & #2. 

Newpark Transfer 

Station Morgan City. 

Newpark Transfer 

Station Port Arthur. 

USLL Galveston and 

Fourchon Transfer 

Station 

Unused brine can 

be returned to 

vendor and/or 

stored for use on 

another job. 

Used brine and 

spent acid is 

transferred to 

Newpark's 

Processing & 

Transfer facility 

for injection. 

Workover 

fluids 

Brine, spent 

acid, prop 

sand, debris 

3,000 bbls 3,000 

bbls/well 

Transport 

to shore in 

cuttings 

boxes, 

drums, 

and/or 

vessel tanks 

for pick up 

Sent to Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer 

Station #1 & #2. 

Newpark Transfer 

Station Morgan City. 

Newpark Transfer 

Station Port Arthur. 

USLL Galveston and 

Fourchon Transfer 

Station 

Unused brine can 

be returned to 

vendor and/or 

stored for use on 

another job. 

Used brine and 

spent acid is 

transferred to 

Newpark's 

Processing & 

Transfer facility 

for injection. 

Trash and 

debris 

Refuse 

generated 

during 

operations 

300 bbls 50 

bbls/month 

Transport 

to shore in 

disposal 

bags by 

vessel to 

shorebase 

for pickup 

by 

municipal 

operations 

Recycled Material in 

ARC, New Iberia, LA. 

Trash disposed of at 

SWDI landfill. 

Recycled and/or 

disposed in 

landfill. 

Used oil Excess oil from 

engines 

645 bbls 430 

bbls/120 

days 

Transport 

in totes to 

shore for 

pick up 

American Recovery 

Fourchon, LA 

Recycled 

*Total amount assumes 1 well at 180 days/well 
Green Canyon Blocks 683 and 727 

Environmental Impact Analysis 

Figure 1. Location of Green Canyon Blocks 683 and 727.
 

L 

ONSHORE SUPPORT FACILITIES INFORMATION

(a) General 

Per NTL No. 2008-G04, the following tables reflect the onshore facilities Anadarko will utilize to 

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

 

Name Primary Location Existing/New/Modified 

Anadarko Service Base Fourchon, Louisiana Existing 

Name *Alternate Locations Existing/New/Modified 

Anadarko Service Base Galveston, TX Existing 

Anadarko Service Base Cameron, LA Existing 

Anadarko Service Base Pascagoula, MS Existing 

*In the unlikely event Anadarko’s primary service base cannot be utilized Anadarko will 

exercise the use of an alternate service base during drilling and/or completion operations. 

(b) Support Base 

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

(c) Waste Disposal 

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

means other than by release into the water of the GOM at the site where they are generated. 

These wastes can be disposed of by offsite release, injection, encapsulation, or placement at either 

onshore or offshore permitted locations for the purposes of returning them back to the 

environment. 

Type of 

Waste 

Composition Total 

Projected 

Amount 

Rate Transport 

Method 

Name/Location of 

Facility 

Disposal 

Method 

Syntheticbased drilling 

fluid or mud 

Synthetic- based 

drilling muds 

14,000 bbls 14,000 

bbls/well 

Re-use 

and/or 

transport to 

shore in 

tanks. 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Station Port Arthur. USLL 

Galveston and Fourchon 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 

dipsosal facility) or 

USLL (landfarm). 

Cuttings 

wetted with 

syntheticbased muds 

Cuttings coated 

with synthetic 

drilling muds, 

including drilled 

out cement 

400-800 bbls 400-800 

bbls/well* 

*An 

estimated 

5-10% of 

cuttings may 

be 

Re-use 

and/or 

transport to 

shore in 

tanks and/or 

cutting 

boxes. 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Station Port Arthur. USLL 

Galveston and Fourchon 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 

disposal facility) or 

USLL (landfarm). 
 

transported 

to shore 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

Chemical 

product 

waste (well 

treatment 

fluids) 

Ethylene glycol 

Methanol 

600 bbls 

150 bbls 

100 

bbls/month 

25 

bbls/month 

Transport 

to shore in 

drums 

and/or tote 

tanks for 

pick up 

Chemwaste in Sulphur, 

LA and Veolia Port 

Arthur, TX or to 

Newpark, Port Arthur 

as non-hazardous waste. 

Can be returned 

to vendor and/or 

used at another 

facility; MEG is 

solidified and 

disposed of in a 

landfill. 

Methanol is 

incinerated or 

used for fuels 

blending. 

Completion 

fluids 

Brine, spent 

acid, prop 

sand, debris 

3,000 bbls 3,000 

bbls/well 

Transport 

to shore in 

cuttings 

boxes, 

drums, 

and/or 

vessel tanks 

for pick up 

Sent to Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer 

Station #1 & #2. 

Newpark Transfer 

Station Morgan City. 

Newpark Transfer 

Station Port Arthur. 

USLL Galveston and 

Fourchon Transfer 

Station 

Unused brine can 

be returned to 

vendor and/or 

stored for use on 

another job. 

Used brine and 

spent acid is 

transferred to 

Newpark's 

Processing & 

Transfer facility 

for injection. 

Workover 

fluids 

Brine, spent 

acid, prop 

sand, debris 

3,000 bbls 3,000 

bbls/well 

Transport 

to shore in 

cuttings 

boxes, 

drums, 

and/or 

vessel tanks 

for pick up 

Sent to Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer 

Station #1 & #2. 

Newpark Transfer 

Station Morgan City. 

Newpark Transfer 

Station Port Arthur. 

USLL Galveston and 

Fourchon Transfer 

Station 

Unused brine can 

be returned to 

vendor and/or 

stored for use on 

another job. 

Used brine and 

spent acid is 

transferred to 

Newpark's 

Processing & 

Transfer facility 

for injection. 

Trash and 

debris 

Refuse 

generated 

during 

operations 

300 bbls 50 

bbls/month 

Transport 

to shore in 

disposal 

bags by 

vessel to 

shorebase 

for pickup 

by 

municipal 

operations 

Recycled Material in 

ARC, New Iberia, LA. 

Trash disposed of at 

SWDI landfill. 

Recycled and/or 

disposed in 

landfill. 

Used oil Excess oil from 

engines 

645 bbls 430 

bbls/120 

days 

Transport 

in totes to 

shore for 

pick up 

American Recovery 

Fourchon, LA 

Recylcled 

*Total amount assumes 1 well at 180 days/well 
 

M 

COASTAL ZONE MANAGEMENT ACT INFORMATION 
 

The following is an evaluation that includes findings relating the coastal effects of the proposed 

activities and associated facilities to the relevant enforceable policies of the Texas’ Coastal 

Management Program (TCMP), Title 31, Part 16, Chapter 501, Subchapter B:

(Category 2) 

Construction, Operation & Maintenance of Oil & Gas Exploration & Production 

Facilities 

No operations are proposed in or near any critical areas. The proposed activities are explorative in 

nature, so no facility construction is proposed. The proposed activities are located approximately 

230 miles from the Texas shoreline; therefore we expect no adverse impacts to CNRAs or beach 

access and use rights of the public. All activities shall be conducted in a manner that minimizes 

significant impacts to coastal resources. No adverse effects to Texas’ coastal area are expected in 

association with the proposed activities. 

(Category 3) 

Discharges of Wastewater and Disposal of Waste from Oil and Gas Exploration and 

Production Activities 

No discharge of wastewater or disposal of waste from the proposed activities will occur in the 

Texas’ coastal zone; therefore no impact to Texas’ coastal waters is expected. 

(Category 4) 

Construction and Operation of Solid Waste Treatment, Storage, and Disposal 

Facilities 

No construction of solid waste facilities or expansion of existing facilities in the coastal zone are 

proposed in the attached plan, therefore, no adverse effects on any features of Texas’ coastal cone 

are expected. 

(Category 5) 

Prevention, Response, and Remediation of Oil Spills 

The proposed activities will be covered under an approved Regional Oil Spill Response Plan. The 

plan is in place, practiced, and updated as necessary. The best practical techniques shall be 

utilized to prevent the release of pollutants or toxic substances into the environment. All involved 

vessels and facilities are designed to be capable of prompt response and adequate removal of 

accidental discharges of oil. In addition, the proposed activities are 230 miles from shore; 

therefore no damages to natural resources are expected as the result of an unauthorized discharge 

of oil into coastal waters. 

(Category 6) 

Discharge of Municipal and Industrial Waste Water to Coastal Waters 

No discharges from the proposed activities will occur in coastal waters. The proposed activities 

are 230 miles from shore; therefore there will be no effect on coastal waters. 
 

(Category 8) 

Development in Critical Areas 

None of the proposed activities will occur in a critical area; therefore no effects to Texas’ coastal 

zone are expected. The activity will not jeopardize the continued existence of species listed as 

endangered or threatened, and will not result in likelihood of the destruction or adverse 

modification of a habitat determined to be a critical habitat under the Endangered Species Act. 

The activity will not cause or contribute to violation of any applicable surface water quality 

standards. The activity will not violate any requirement imposed to protect a marine sanctuary. 

(Category 9) 

Construction of Waterfront Facilities and Other Structures on Submerged lands 

No waterfront facilities or other structures are proposed on submerged lands in the Texas coastal 

zone, therefore the proposed activities are not expected to have any adverse impacts on 

submerged lands. 

(Category 10) 

Dredging and Dredged Material Disposal and Placement 

No dredging or disposal/placement of dredged material is proposed; therefore no adverse effects 

to coastal waters, submerged lands, critical areas, coastal shore areas, or Gulf beaches are 

expected. 

(Category 11) 

Construction in the Beach / Dune System 

The proposed activities do not include any construction projects in critical dune areas or areas 

adjacent to or on Gulf beaches, therefore, no impact to Texas’ beach or dune systems are 

expected. 

(Category 15) 

Alteration of Coastal Historic Areas 

The proposed activities do not include any alteration or disturbance of a coastal historic area; 

therefore, no impacts are expected to adversely affect any historical, architectural, or 

archaeological site in Texas’ coastal zone. 

(Category 16) 

Transportation 

The proposed activities do not include any transportation construction projects within the coastal 

zone; therefore, no impacts to Texas’ coastal zone are expected. 

(Category 17) 

Emission of Air Pollutants 

The proposed activities shall be carried out in conformance with applicable air quality laws, 

standards, and regulations. Emissions from the proposed activities are not expected to have 

significant impacts on onshore air quality because of the prevailing atmospheric conditions, 

emission heights, emission rates, and the distance of these emissions from the coastline. The 
 

proposed activities will occur approximately 230 miles from shore and will be within the 

exemption limits set by BOEM, therefore, no impacts to Texas’ coastal zone is expected. 

(Category 18) 

Appropriations of Water 

The proposed activities do not include the impoundment or diversion of state water, therefore, no 

impacts to Texas’ coastal zone is expected. 

(Category 20) 

Marine Fishery Management 

The proposed activities are located approximately 230 miles from shore and are not expected to 

have any effect on marine fishery management or fishery migratory patterns within waters in the 

coastal zone of Texas. 

(Category 22) 

Administrative Policies 

The necessary information for applicable agencies to make an informed decision on the proposed 

activities has been provided In conclusion, all activities shall be consistent with Texas’ coastal 

management program and shall comply with all relevant rules and regulations. No activities are 

planned within any critical areas. Activities will be carried out avoiding unnecessary conflicts 

with other uses of the vicinity. 

 

MISSISSIPPI COASTAL ZONE MANAGEMENT ACT INFORMATION 

As authorized by the Federal Coastal Zone Management Act (CZMA), The State of 

Mississippi developed a Coastal Management Program (CMP) to allow for the review of 

proposed Federal license and permit activities affecting any coastal use or resources, in or 

outside of the Mississippi Coastal Zone. 

The OCS related oil and gas exploratory and development activities having potential 

impact on the Mississippi Coastal Zone are based on the location of the proposed 

facilities, access to those sites, best practical techniques for drilling locations, drilling 

equipment guidelines for the prevention of adverse environmental effects, effective 

environmental protection, emergency plans and contingency plans. 

Below are goals identified by the State of Mississippi and our comments and/or 

corresponding cross references: 

Goal 1: To provide for reasonable industrial expansion in the coastal area and to 

ensure the efficient utilization of waterfront industrial sites so that suitable sites are 

conserved for water dependent industry. 

The activities proposed in this plan are based out of Fourchon, Louisiana. The activities 

will not provide any industrial expansion on the coastal area of Mississippi. Therefore 

Mississippi coastal areas will be conserved for water dependent industry. 

Goal 2: To favor the preservation of the coastal wetlands and ecosystems, except 

where a specific alteration of specific coastal wetlands would serve a higher public 

interest in compliance with the public purposes of the public trust in which the 

coastal wetlands are held. 

Goal 2 is addressed in Section N, Environmental Impact Analysis. The nearest proposed 

activities will be 195 miles from the Mississippi coast. 

Goal 3: To protect, propagate and conserve the state’s seafood and aquatic life in 

connection with the revitalization of the seafood industry of the State of Mississippi. 

Goal 3 is addressed in Section N, Environmental Impact Analysis. Little impact to the 

seafood industry can be expected due to the activities occurring 195 miles from the 

Mississippi coast. 

Goal 4: To conserve the air and waters of the state, and to protect, maintain and 

improve the quality thereof for public use, for the propagation of wildlife, fish and 

aquatic life, and for domestic, agricultural, industrial, recreational and other 

legitimate beneficial uses. 

Goal 4 is addressed in Section B, General Information, Section G, Air Emissions 

Information, and Section N, Environmental Impact Analysis. 
 

Goal 5: To put to beneficial use to the fullest extent of which they are capable the 

water resources of the state, and to prevent the waste, unreasonable use, or 

unreasonable method of use of water. 

The activities proposed in this plan are based in Fourchon, Louisiana. As such, 

Mississippi’s water resources should not be impacted by the proposed activities. 

Activities occurring at the sites in the OCS will be conducted in accordance with our 

Regional Oil Spill Response Plan referenced in Section H of this plan. 

Goal 6: To preserve the state’s historical and archaeological resources, to prevent 

their destruction, and to enhance these resources wherever possible. 

Goal 6 is addressed in Section E, Biological, Physical and Socioeconomic Information, 

and Section N, Environmental Impact Analysis. 

Goal 7: To encourage the preservation of natural scenic qualities in the coastal area. 

Goal 7 is addressed in Section F, Waste Discharges Information, Section H, Oil Spill 

Information, Section G, Air Emissions Information, and Section N, Environmental 

Impact Analysis. 

Goal 8: To assist local governments in the provision of public facilities services in a 

manner consistent with the coastal program. 

As the proposed activities are located 195 miles from the Mississippi coast and are based 

out of a shorebase in Fourchon, Louisiana, local governments should not be affected. 

 

N

ENVIRONMENTAL IMPACT ANALYSIS 
Environmental Impact Analysis

SUPPLEMENTAL EXPLORATION PLAN

for

Green Canyon Block 683 (OCS G-18421) and

Green Canyon Block 727 (OCS G-16783)

Offshore Louisiana

August 2011

Prepared for:

Jill Fowler

Regulatory Analyst

Anadarko Petroleum Corporation

1201 Lake Robbins Drive 

The Woodlands, Texas 77380

Telephone: (832) 636-1694

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997

Telephone: (772) 219-3000
Green Canyon Blocks 683 and 727 August 2011

Environmental Impact Analysis Page ii

Contents

Page

Introduction ................................................................................................................1

A. Impact-Producing Factors .......................................................................................5

A.1 Drilling Rig Presence (including noise and lights)...........................................................................5

A.2 Physical Disturbance to the Seafloor..............................................................................................8

A.3 Air Pollutant Emissions...................................................................................................................8

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

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

A.6 Onshore Waste Disposal.................................................................................................................9

A.7 Marine Debris.................................................................................................................................9

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

A.9 Accidents ......................................................................................................................................10

A.9.1 Types of Accidents Evaluated ...........................................................................................10

A.9.2 Small Fuel Spill ..................................................................................................................10

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

A.9.4 Other Accidents Not Analyzed in Detail............................................................................15

B. Affected Environment...........................................................................................17

C. Impact Analysis.....................................................................................................19

C.1 Physical/Chemical Environment...................................................................................................19

C.1.1 Air Quality .........................................................................................................................19

C.1.2 Water Quality....................................................................................................................21

C.2 Seafloor Habitats and Biota..........................................................................................................23

C.2.1 Soft Bottom Benthic Communities...................................................................................23

C.2.2 High-Density Deepwater Benthic Communities...............................................................26

C.2.3 Designated Topographic Features....................................................................................28

C.2.4 Pinnacle Trend Area Live Bottoms....................................................................................28

C.2.5 Eastern Gulf Live Bottoms.................................................................................................29

C.3 Threatened, Endangered, and Protected Species and Critical Habitat........................................29

C.3.1 Sperm Whale (Endangered)..............................................................................................31

C.3.2 West Indian Manatee (Endangered).................................................................................34

C.3.3 Endangered Mysticete Whales.........................................................................................35

C.3.4 Non-Endangered Marine Mammals (Protected)..............................................................36

C.3.5 Sea Turtles (Endangered/Threatened) .............................................................................39

C.3.6 Piping Plover (Threatened)...............................................................................................42

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

C.3.8 Gulf Sturgeon (Threatened)..............................................................................................44

C.3.9 Smalltooth Sawfish (Endangered).....................................................................................45

C.3.10 Beach Mice (Endangered).................................................................................................45

C.3.11 Elkhorn Coral (Endangered)..............................................................................................46
Contents

(Continued)

Page

Green Canyon Blocks 683 and 727 August 2011

Environmental Impact Analysis Page iii

C.4 Coastal and Marine Birds..............................................................................................................46

C.4.1 Marine Birds......................................................................................................................46

C.4.2 Shorebirds and Coastal Nesting Birds...............................................................................49

C.5 Fisheries Resources ......................................................................................................................51

C.5.1 Pelagic Communities and Ichthyoplankton ......................................................................51

C.5.2 Essential Fish Habitat........................................................................................................53

C.6 Archaeological Resources.............................................................................................................56

C.6.1 Shipwreck Sites.................................................................................................................56

C.6.2 Prehistoric Archaeological Sites........................................................................................57

C.7 Coastal Habitats and Protected Areas..........................................................................................58

C.8 Socioeconomic and Other Resources...........................................................................................61

C.8.1 Recreational and Commercial Fishing ..............................................................................61

C.8.2 Public Health and Safety ...................................................................................................63

C.8.3 Employment and Infrastructure .......................................................................................63

C.8.4 Recreation and Tourism....................................................................................................64

C.8.5 Land Use............................................................................................................................65

C.8.6 Other Marine Uses............................................................................................................66

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

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

D.2 Severe Weather............................................................................................................................66

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

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

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

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

H. Preparers..............................................................................................................67

I. References.............................................................................................................68
Green Canyon Blocks 683 and 727 August 2011

Environmental Impact Analysis Page iv

List of Tables

Table Page

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

Analysis (EIA) .........................................................................................................................4

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

3 Conditional probabilities expressed as percent chance that an oil spill starting at 

Launch Point 3 will contact a certain parish, county, or coastline within 120 days 

(Modified from: BOEMRE, 2011b, Appendix C) ..................................................................13

4 Benthic community data from stations near the lease area and in greater water 

depths and more distant stations in more similar depths sampled during the 

Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study 

(Adapted from: Wei, 2006; Rowe and Kennicutt, 2009).....................................................24

5 Federally-listed endangered and threatened species potentially occurring in the 

lease area and along the northern Gulf coast.....................................................................30

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

geographic range of the potential shoreline contacts after 120 days 

(From: BOEMRE, 2011a)......................................................................................................59

List of Figures

Figure Page

1 Location of Green Canyon Blocks 683 and 727.....................................................................3

2 Bathymetric map of the lease area showing proposed well surface locations...................18

3 Location of selected environmental features in relation to the lease area........................43
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Acronyms and Abbreviations

ADIOS Automated Data Inquiry for Oil Spills

bbl barrel

BHL bottom hole location

BLPD barrels of liquid per day

BOEMRE Bureau of Ocean Energy Management, 

Regulation and Enforcement

BOPD barrels of oil per day

B.P. Before Present

CEI Coastal Environments, Inc.

CH4 methane

CO carbon monoxide

CO2 carbon dioxide

CFR Code of Federal Regulations

CGA Clean Gulf Associates

DP dynamically positioned 

EP Exploration Plan 

EA Environmental Assessment

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ESA Endangered Species Act

EW Ewing Bank

FAD fish-attracting device

FR Federal Register

GC Green Canyon

GPS global positioning system

GMFMC Gulf of Mexico Fishery Management 

Council

HAPC Habitat Area of Particular Concern

HFRS Helix Fast Response System

HOSS high-volume open sea skimmer

HWCG Helix Well Containment Group

IPF impact-producing factor

MARPOL International Convention for the 

Prevention of Pollution from Ships

MGD million gallons per day

MMBO million barrels of oil

MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MMSCFD million standard cubic feet per day

MWCC Marine Well Containment Company

NAAQS National Ambient Air Quality 

Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric 

Administration

NOx nitrogen oxides

NPDES National Pollutant Discharge 

Elimination System

NPS National Park Service

NRC National Response Corporation

NRDA Natural Resource Damage Assessment

NTL Notice to LesseeNWR National 

Wildlife Refuge

OBM oil-based mud

OCS Outer Continental Shelf

OSAT Operational Scientific Advisory Team

OSRA Oil Spill Risk Analysis

OSRP Oil Spill Response Plan

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

SBF synthetic-based fluid

SBM synthetic-based mud

SHL surface hole location

SOx sulfur oxides

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
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Introduction

Anadarko Petroleum Corporation (Anadarko) is submitting a Supplemental Exploration Plan (EP) 

for Green Canyon Blocks 683 and 727 (GC 683 and 727). The EP includes one well designated 

GC 727 #002 to be drilled and completed with the surface hole location (SHL) in the southcentral portion of GC 683 and bottom hole location (BHL) in GC 727. This Environmental Impact 

Analysis (EIA) provides information on the exploratory well based on the SHL and BHL.

The lease area is 120 miles (194 km) south of the nearest shoreline, 131 miles (211 km) from the 

onshore support base at Port Fourchon, Louisiana, and 159 miles (259 km) from the helicopter 

base at Houma, Louisiana (Figure 1). Water depth at wellsite GC 727 #002 is 1,367 m (4,484 ft) 

The drilling rig is yet to be determined but will be either a dynamically positioned (DP) drillship

or a DP semisubmersible.

This EIA was prepared for submittal to the Bureau of Ocean Energy Management, Regulation 

and Enforcement (BOEMRE, formerly Minerals Management Service [MMS]) in accordance with 

applicable regulations, and is a project- and site-specific analysis of Anadarko’s planned 

activities. As specified in the Notice to Lessees and Operators (NTL) 2008-G04, an EIA is a 

project-specific analysis that focuses on the impacts of a specific plan to the extent feasible. 

Potential impacts have been analyzed at a broader level in the Programmatic Environmental 

Impact Statement (EIS) for the Outer Continental Shelf (OCS) Oil and Gas Leasing Program 

(MMS, 2007a) and in lease sale EISs for the Western and Central Gulf of Mexico Planning Areas 

(MMS, 2007b, 2008). The analyses from these documents are incorporated here by reference. 

Also incorporated are the post-Macondo incident Draft Supplemental EIS for the Central 

Planning Area and Final Supplemental EIS for the Western Planning Area lease sales 

(BOEMRE, 2011a,b), which present updated environmental baseline information relative to the 

Macondo incident, have been reviewed. 

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

evaluating oil spill risk during exploratory drilling. According to Holand (1997), the average 

frequency of a loss of well control incident or “blowout” during exploratory drilling in the 

U.S. Gulf of Mexico is 0.00593 blowouts per well drilled, or one blowout per 169 exploration 

wells drilled. Similarly, the MMS Safety and Environmental Management Program blowout 

incident rate for 1996 to 1999 was approximately five blowouts per 1,000 well starts, or one 

blowout per 200 well starts (MMS, 2000). More recently, in its Draft Supplemental EIS for the 

Central Gulf of Mexico Planning Area, BOEMRE confirmed that “significant changes to the spill 

rates for the entire OCS are not anticipated” (BOEMRE, 2011a).

Historically, most blowouts have not resulted in oil spills. Of 151 well blowouts in the Gulf of 

Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills, with a total combined volume of 

1,000 barrels (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). 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.
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Anadarko submitted an updated Gulf of Mexico Regional Oil Spill Response Plan (OSRP) to 

BOEMRE on 21 July 2011. In addition, Anadarko submitted a Regional OSRP Certification Letter 

per 30 Code of Federal Regulations (CFR) 254.2(b) to BOEMRE on 21 July 2011. The Certification 

Letter was accepted by BOEMRE on 27 July 2011. The OSRP details Anadarko’s plan for response 

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

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

response to spills ranging from small operational spills to a worst case discharge (WCD) from a 

well blowout. Anadarko’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 Anadarko’s regional oil spill organization and dedicated response assets, 

potential spill risks, and local environmental sensitivities. The OSRP describes personnel and 

equipment mobilization, the incident management team organization, and an overview of 

actions and notifications to be taken in the event of a spill.

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

NTL 2008-G04. The main impact-related discussions are in Section A (Impact-Producing Factors) 

and Section C (Impact Analysis). Table 1 lists and summarizes the NTLs applicable to this EIA.
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Figure 1. Location of Green Canyon Blocks 683 and 727.
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Table 1. Notices to Lessees and Operators (NTLs) referenced in this Environmental Impact 

Analysis (EIA).

NTL Title Summary

2010-N10

Statement of Compliance with 

Applicable Regulations and 

Evaluation of Information 

Demonstrating Adequate Spill 

Response and Well Containment 

Resources

Informs operators using subsea blowout preventers (BOPs) or 

surface BOPs on floating facilities that applications for well 

permits must include a statement signed by an authorized 

company official stating that the operator will conduct all 

activities in compliance with all applicable regulations, including 

the increased safety measures regulations (75 FR 63346). 

Informs operators that BOEMRE will be evaluating whether each 

operator has submitted adequate information demonstrating 

that it has access to and can deploy containment resources to 

promptly respond to a blowout or other loss of well control.

2010-N06

Information Requirements for 

Exploration Plans, Development and 

Production Plans, and Development 

Operations Coordination Documents 

on the OCS

Rescinds the limitations set forth in NTL 2008-G04 regarding a 

blowout scenario and worst case discharge scenario, and 

provides guidance regarding the information required in blowout 

scenario and worst case discharge scenario descriptions.

2009-G40 Deepwater Benthic Communities

Guidance for avoiding and protecting high-density deepwater 

benthic communities (including chemosynthetic and deepwater 

coral communities) from damage caused by Outer Continental 

Shelf (OCS) oil and gas activities in water depths greater than 

300 m (984 ft). Prescribes separation distances of 610 m 

(2,000 ft) from each mud and cuttings discharge location and 

76 m (250 ft) from all other seafloor disturbances.

2009-G39 Biologically-Sensitive Underwater 

Features and Areas

Guidance for avoiding and protecting biologically sensitive 

features and areas (i.e., topographic features, pinnacles, low 

relief live bottom areas, and other potentially sensitive biological 

features) when conducting OCS operations in water depths less 

than 300 m (984 ft) in the Gulf of Mexico.

2009-G06 Military Warning and Water Test 

Areas

Provides contact links to individual command headquarters for 

the military warning and water test areas in the Gulf of Mexico. 

Lease stipulations require lessees or designated operators to 

enter into an agreement with the appropriate individual military 

command headquarters concerning the control of 

electromagnetic emissions and use of boats and aircraft in the 

applicable warning area or water test area before commencing 

such traffic.

2008-G04

Information Requirements for 

Exploration Plans and Development 

Operations Coordination Documents

Guidance on the information requirements for OCS plans, 

including EIA requirements and information regarding 

compliance with the provisions of the Endangered Species Act 

and Marine Mammal Protection Act.

2007-G04

Vessel Strike Avoidance and 

Injured/Dead Protected Species 

Reporting

Recommends protected species identification training, 

recommends that vessel operators and crews maintain a vigilant 

watch for marine mammals and slow down or stop their vessel 

to avoid striking protected species, and requires operators to 

report sightings of any injured or dead protected species.

2007-G03 Marine Trash and Debris Awareness 

and Elimination

Instructs operators to exercise caution in the handling and 

disposal of small items and packaging materials; requires the 

posting of placards at prominent locations on offshore vessels 

and structures; and mandates a yearly marine trash and debris 

awareness training and certification process.

2005-G07 Archaeological Resource Surveys 

and Reports

Provides guidance on regulations regarding archaeological 

discoveries, specifies requirements for archaeological resource 

surveys and reports, and outlines options for protecting 

archaeological resources.
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A. Impact-Producing Factors

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

resources adapted from Form MMS-142. An “X” indicates that an IPF could reasonably be 

expected to affect a certain resource, and a dash (--) indicates no impact or negligible impact. 

Where there may be an effect, an analysis is provided in Section C. Potential IPFs for the 

proposed activity are listed below and briefly discussed in the following 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)

Two types of exploratory drilling rigs are available for this project:

• Dynamically-positioned (DP) drillship; and

• DP semisubmersible.

DP drillships and DP semisubmersibles use a global positioning system (GPS), specific computer 

software, and sensors in conjunction with and their own propellers and thrusters to maintain 

position. Essentially, through satellite navigation and, the location of the vessel is precisely 

monitored, and thrusters positioned at various locations about the vessel’s hull are activated to 

provide any required stationkeeping adjustment. This allows operations at sea where mooring 

or anchoring is not feasible.

The drilling vessel for the well proposed in this EP will be on site for an estimated 150 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 and 

semisubmersibles is not particularly intense and is strongest at low frequencies, averaging 

10 to 500 Hz (Richardson et al., 1995). From a drilling rig, sound and vibration paths to the 

water flow either through the air or through the risers (MMS, 2000). Drilling rigs also maintain 

exterior lighting for navigational and aviation safety in accordance with applicable Federal safety 

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

Environmental Resources

Impact-producing Factors

Drilling Rig 

Presence (incl. 

noise & lights)

Physical 

Disturbance 

to Seafloor

Air 

Pollutant 

Emissions

Effluent 

Discharges

Water 

Intake

Onshore 

Waste 

Disposal

Marine 

Debris

Support 

Vessel/Helo 

Traffic

Accidents

Small Fuel 

Spill

Oil Spill 

(WCD)

Physical/Chemical Environment

Air quality and greenhouse gases -- -- --X(9) -- -- -- -- -- X(6) X(6)

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

Seafloor Habitats and Biota

Soft bottom benthic communities -- X -- X -- -- -- -- -- X(6)

High-density deepwater benthic communities -- --(4) -- X(4) -- -- -- -- -- X(6)

Designated topographic features -- --(1) -- --(1) -- -- -- -- -- --

Pinnacle trend area live bottoms -- --(2) -- --(2) -- -- -- -- -- --

Eastern Gulf live bottoms -- --(3) -- --(3) -- -- -- -- -- --

Threatened, Endangered, and Protected Species and Critical Habitat

Sperm whale (endangered) X(8) -- -- -- -- -- -- X(8) X(6,8) X(6,8)

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

Endangered mysticete whales -- -- -- -- -- -- -- -- -- --

Non-endangered marine mammals (protected) X -- -- -- -- -- -- X X(6) X(6)

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

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

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

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

Smalltooth sawfish (endangered) -- -- -- -- -- -- -- -- -- X(6)

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

Elkhorn coral (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.
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Table 2 Footnotes and Applicability:

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

anchors will be on the seafloor within the following:

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

(b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) protected by the Topographic 

Features Stipulation attached to an Outer Continental Shelf (OCS) lease;

(c) Essential Fish Habitat (EFH) criteria of 500 ft from any no-activity zone; or

(d) Proximity of any submarine bank (500-ft buffer zone) with relief greater than 2 m that is not protected by 

the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or 

no-activity zone. There are no submarine banks in the blocks.

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom 

(Pinnacle Trend) Stipulation attached to an OCS lease.

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

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

(Low-Relief) Stipulation attached to an OCS lease. 

• The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area.

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

• No impacts on high-density deepwater benthic communities are anticipated. There are no features 

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

any drilling mud/cuttings discharge location. 

(5) Exploration or production activities where H2S concentrations greater than 500 ppm might be encountered. 

• Previously drilled wells in the GC 683 and 727 area did not indicate the presence of H2S and BOEMRE has 

classified the area as “H2S absent” in accordance with CFR 250.490(c).

(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 BOEMRE as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such 

blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the 

proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would 

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

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

blocks for shipwrecks and is well beyond the 60-m depth contour used by the BOEMRE as the seaward 

extent for prehistoric archaeological site potential in the Gulf of Mexico.

(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals 

or sea turtles or their critical habitats. 

• IPFs that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence 

and emissions, support vessel and helicopter traffic, and accidents. See Section C.

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

• Not applicable.
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A.2 Physical Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP drillships and DP semisubmersibles disturb 

only a very small area of the seafloor around the wellbore (SHL) where the bottom template and 

blowout preventer are located. Depending upon the specific well configuration, this area is 

generally about 0.25 ha (0.62 ac).

A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in EP Section G and are estimated to be insignificant. 

Offshore air pollutant emissions will result from operations of the drilling rig, as well as service 

vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The 

combustion of fuels occurs on diesel-powered generators, pumps, or motors and from lighter 

fuel motors. Primary air pollutants typically associated with OCS activities are suspended 

particulate matter (PM), sulfur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds 

(VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accordance with BOEMRE requirements 

demonstrates that the projected emissions are below exemption levels set by the applicable 

regulations in 30 CFR 250.303. Based on this and the distance to shore, it can be concluded that

the emissions will not significantly affect the air quality of the onshore area for any of the 

criteria pollutants. No further analysis or control measures are required.

A.4 Effluent Discharges

Effluent discharges are summarized in EP Section F. All offshore discharges will be in 

accordance with requirements of the National Pollutant Discharge Elimination System (NPDES) 

General Permit No. GMG290000 issued by the U.S. Environmental Protection Agency (USEPA). 

Any discharges will be in compliance with the permit terms and 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 in an 

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

with the NPDES permit.

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

non-contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination 

unit brine, uncontaminated fresh water and seawater, and ballast water.

A.5 Water Intake

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery on 

the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the 

location, design, construction, and capacity of cooling water intake structures reflect the best 

technology available to minimize adverse environmental impact from impingement and 

entrainment of aquatic organisms. The current NPDES General Permit No. GMG 290000 does 
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Environmental Impact Analysis Page 9

not specify requirements for existing facilities (those that started construction before 

16 July 2006). The rigs being considered for use for activities described in this EP are not “new” 

facilities as defined by the NPDES permit and therefore are not subject to the cooling water 

intake regulations.

A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F. Approximately 50 bbl of trash 

will be generated each month of operations, or a total of 300 bbl over the life of this project. 

This trash will be transported in disposal bags to shore, where it will be picked up by municipal 

operators for final disposal in accordance with applicable regulations. 

A.7 Marine Debris

Anadarko will comply with all regulations relating to solid wastes handling and disposal, 

including the International Convention for the Prevention of Pollution from Ships 

(MARPOL 73/78) Annex V requirements and USEPA and U.S. Coast Guard (USCG) regulations, as 

well as those of the BOEMRE. For example, BOEMRE regulations at 30 CFR 250.300(a) and 

(b)(6) prohibit operators from deliberately discharging containers and other similar materials 

(i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable 

identification markings on equipment, tools, and containers (especially drums), and other 

material. 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 accidental loss of solid waste. In addition to the 

regulations in 30 CFR 250, MMS issued NTL 2007-G03, which instructs operators to exercise 

caution in the handling and disposal of small items and packaging materials, requires the posting 

of placards at prominent locations on offshore vessels and structures, and mandates a yearly 

marine trash and debris awareness training and certification process.

A.8 Support Vessel and Helicopter Traffic

Anadarko will use existing shorebase facilities at Port Fourchon, Louisiana, for onshore support 

for vessel activities. Air transportation (helicopters) will be based at facilities in Houma, Louisiana. 

No terminal expansion or construction is planned at either location.

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

make three round-trips per week, and the supply vessel will make two round-trips per week. 

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

A helicopter will make one round-trip daily between the drilling rig and the heliport. The 

helicopter will be used to transport personnel and small supplies and will normally take the 

most direct route of travel between the shorebase and the lease area when air traffic and 

weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m (700 ft) 

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.
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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 Anadarko’s spill response plans. Impacts are analyzed in Section C.

MMS (2007b) and BOEMRE (2011a,b) analyze three other types of accidents: 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 BOEMRE (2011a,b), 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, 2011a,b). The 

average size for spills <1 bbl is 0.07 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl

(MMS, 2007b). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational 

experience suggests that the most likely cause of such a spill would be a hose rupture resulting 

in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic 

aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council, 2003). 

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

degraded by aerobic microbial oxidation. Diesel is so light that it will not sink to the seafloor. 

Diesel dispersed in the water column can adhere to suspended sediments, but this generally 

occurs only in coastal areas with high suspended solids loads (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, 2011a,b).

For purposes of this EIA, the fate of a small diesel fuel spill was estimated using NOAA’s ADIOS2 

(Automated Data Inquiry for Oil Spills) model. This model uses the physical properties of oils in 

its database to predict the rate of evaporation and dispersion over time, as well as changes in 

the density, viscosity, and water content of the product spilled. It is estimated that over 90% of 

a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea 

surface with diesel fuel on it during this 24-hour period would range from 0.5 to 5 ha 

(1.2 to 12 ac) depending on sea state and weather conditions.
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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 120 miles (194 km) from the nearest shoreline. Modeling results discussed 

below indicate that a spill in the lease area would have a 4% or less probability of reaching the 

coastal areas of Louisiana within 10 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 Anadarko’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

A.9.3 Crude Oil Spill (Worst Case Discharge)

. In the unlikely event the shipboard prevention procedures fail to prevent a fuel 

spill, response equipment and trained personnel would be activated so that any spill effects 

would be localized and would result only in short-term environmental consequences. 

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

Spill Size

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) 

estimated a probability of 0.0021 for a 

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

for this EP as 340,281barrels of oil per day (BOPD). The estimated time to drill a relief well is 

between 132 and 146 days from the time of a blowout until the relief well is completed. The 

total volume of a spill over this duration (146 days) would be 49,681,026 barrels of oil. The 

detailed analysis of this calculation can be found in EP Section H.

deep drilling

Included in EP Section H are Anadarko’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. Anadarko 

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

additional safety measures for OCS activities.

blowout during exploration drilling based on 

U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout 

frequency of 0.0017 per exploratory well for non-North Sea locations (International Association 

of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts 

lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEMRE is in 

the process of updating these spill frequency estimates to include the recent Macondo event; 

however, significant changes to the spill rates for the entire OCS are not anticipated 

(BOEMRE, 2011a,b). As noted in the Introduction, the baseline risk of a catastrophic blowout is 

estimated to be once every 26 years (BOEMRE Interim Final Drilling Safety Rule, 75 FR 63365, 

10 October 2010). 

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. Although this model has received some criticism recently (Earthjustice, 2011), 

it is still the most widely scientifically accepted model for estimating the fate of small fuel spills. 

The primary criticism of the OSRA model results as provided in Ji et al. (2004) was that the 
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model did not evaluate the fate of a spill over time periods longer than 30 days, nor does it 

predict the fate of a release that continues over a period of weeks or months, as in the Macondo 

(Deepwater Horizon) incident. Also as noted by Ji et al. (2004), the OSRA model does not take 

into account the chemical composition or biological weathering of oil spills, the spreading and 

splitting of oil spills, or spill response activities. The model does not assume a particular spill size 

but has generally been used by the BOEMRE/MMS to evaluate contact probabilities for spills 

greater than 1,000 bbl.

To address this criticism, a special OSRA run was conducted for the recent BOEMRE Central and 

Western Gulf of Mexico Planning Area Supplemental EISs (BOEMRE, 2011a,b) in order to 

estimate the impacts of a possible future catastrophic long-duration oil spill. In this OSRA model 

run a hypothetical high volume, long-duration oil spill was assumed to have occurred, and the 

analysis emphasized modeling a spill that continued for 90 consecutive days, with each 

trajectory tracked for up to 120 days.

The OSRA model run for this revised analysis was conducted for five hypothetical launch points 

in the Central and Western Gulf of Mexico Planning Areas. These launch points were 

deliberately located in areas identified as having a high possibility of containing large oil 

reserves. 

The five launch point areas were as follows:

1. Central Gulf of Mexico shelf area west of the Mississippi River (28.98660° N 

latitude, 92.17851° W longitude);

2. Central Gulf of Mexico shelf area east of the Mississippi River (29.91388° N latitude, 

88.15338° W longitude);

3. Central Gulf of Mexico slope area (27.31998° N latitude, 90.22203° W longitude);

4. Western Gulf of Mexico shelf area (27.55423° N latitude, 96.76627° W longitude); and

5. Western Gulf of Mexico slope area (27.51367° N latitude, 94.51836° W longitude).

The results for Launch Point 3, the nearest location to this project area, are presented in 

Table 3.

OSRA is a preliminary risk assessment model. In the event of an actual oil spill, real-time 

monitoring and trajectory modeling would be conducted using current and wind data available 

from the rigs and permanent production structures in the area. Satellite and aerial monitoring 

of the plume and real-time trajectory modeling using wind and current data would continue on 

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

major spill or uncontrolled release.

Weathering. Following an oil spill, several physical, chemical, and biological processes, 

collectively called weathering, interact to change the physical and chemical properties of the oil, 

influencing potential effects to marine organisms and ecosystems. The most important 

weathering processes include spreading, evaporation, dissolution, dispersion into the water 

column, formation of water-in-oil emulsions, photochemical oxidation, microbial degradation, 

adsorption to suspended particulate matter, and stranding on shore or sedimentation to the 

seafloor (National Research Council, 2003).
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Table 3. Conditional probabilities expressed as percent chance that an oil spill starting at 

Launch Point 3 will contact a certain parish, county, or coastline within 120 days

(Modified from: BOEMRE, 2011b, Appendix C).

Season Winter Spring Summer Fall

Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

County or Parish Percent Chance

Cameron, Texas -- -- -- 2 -- -- -- -- -- -- -- 2 -- -- -- 2

Willacy, Texas -- -- -- 3 -- -- -- -- -- -- -- 2 -- -- -- 3

Kenedy, Texas -- -- -- 8 -- -- -- 1 -- -- -- 9 -- -- -- 5

Kleberg, Texas -- -- 1 6 -- -- -- -- -- -- -- 4 -- -- 1 6

Nueces, Texas -- -- 1 6 -- -- -- -- -- -- -- 2 -- -- 1 2

Aransas, Texas -- -- -- 5 -- -- -- 1 -- -- -- 3 -- -- -- 2

Calhoun, Texas -- -- 1 6 -- -- -- -- -- -- -- 6 -- -- 1 4

Matagorda, Texas -- -- 2 17 -- -- 3 4 -- -- -- 11 -- -- 1 6

Brazoria, Texas -- -- 3 12 -- -- 1 3 -- -- 2 8 -- -- 1 5

Galveston, Texas -- -- 3 10 -- -- 3 6 -- -- 2 5 -- -- 1 4

Jefferson, Texas -- -- 1 4 -- -- 7 9 -- -- 1 1 -- -- -- 2

Cameron, Louisiana -- -- 1 4 -- -- 11 12 -- 1 1 4 -- -- -- 4

Vermilion, Louisiana -- -- 1 2 -- -- 5 6 -- 1 1 2 -- -- -- --

Iberia, Louisiana -- -- -- 1 -- -- 4 4 -- -- -- -- -- -- -- --

Terrebonne, Louisiana -- 1 2 3 -- 4 12 14 -- -- -- 2 -- -- -- --

Lafourche, Louisiana -- -- 1 1 -- 2 8 10 -- -- 1 2 -- -- -- --

Jefferson, Louisiana -- -- -- 1 -- -- 2 2 -- -- 1 1 -- -- -- --

Plaquemines, Louisiana -- -- -- 1 -- 2 10 12 -- -- 1 2 -- -- -- --

Jackson, Mississippi -- -- -- -- -- -- 1 1 -- -- -- -- -- -- -- --

Baldwin, Alabama -- -- -- -- -- -- 1 1 -- -- -- -- -- -- -- --

Bay, Florida -- -- -- -- -- -- -- 1 -- -- -- -- -- -- -- --

Franklin, Florida -- -- -- 1 -- -- -- -- -- -- -- -- -- -- -- --

Monroe, Florida -- -- -- -- -- -- -- -- -- -- -- 1 -- -- -- 1

Dade, Florida -- -- -- -- -- -- -- -- -- -- -- 1 -- -- -- --

“--” = Values <1.0%. Areas where there is <0.5% chance of contact within 120 days are not shown.

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. BOEMRE has issued recent NTLs following the Macondo spill that clarify 

additional oil-spill prevention and response planning requirements. These NTLs are summarized 

in Table 2, and additional BOEMRE (2011a) guidance is provided below.

NTL 2010-N10 – Statement of Compliance with Applicable Regulations and Evaluation of 

Information Demonstrating Adequate Spill Response and Well Containment Resources: 

This NTL, effective November 8, 2010, applies only to operators conducting operations using 

subsea or surface BOPs on floating facilities. It explains that lessees and operators submit a 

statement signed by an authorized company official with each application for a well permit 

indicating that they will conduct all of their authorized activities in compliance with all 

applicable regulations, including the Increased Safety Measures Regulations at 75 FR 63346. 
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The NTL also informs lessees that BOEMRE will be evaluating whether or not each operator 

has submitted adequate information demonstrating that it has access to and can deploy 

surface and subsea containment resources that would be adequate to promptly respond to 

a blowout or other loss of well control. The NTL notifies the operator that BOEMRE intends 

to evaluate the adequacy of each operator to comply in the operator’s current OSRP; 

therefore, there is an incentive for voluntary compliance.

NTL 2010-N06 – Information Requirements for Exploration Plans, Development and 

Production Plans, and Development Operations Coordination Documents on the OCS

Anadarko submitted an updated Gulf of Mexico Regional OSRP to BOEMRE on 21 July 2011. In 

addition, Anadarko submitted a Regional OSRP Certification Letter per 30 CFR 254.2(b) to 

BOEMRE on 21 July 2011. The OSRP provides a detailed plan for Anadarko to respond to and 

rapidly and effectively manage oil spills that may result from drilling and production operations. 

The OSRP contains detailed information on “Quick Response” procedures including

:

This NTL, effective June 18, 2010, explains the procedures for the lessee or operator to 

submit supplemental information for new or previously submitted EPs, DPPs, or DOCDs. 

The required supplemental information includes the following: 1) a description of the 

blowout scenario as required by 30 CFR 250.213(g) and 250.243(h); 2) a description of their 

assumptions and calculations used in determining the volume of the worst-case discharge 

required by 30 CFR 250.219(a)(2)(iv) (for EPs) or 30 CFR 250.250(a)(2)(iv) (for DPPs and 

DOCDs); and 3) a description of the measures proposed that would enhance the ability to 

prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early 

intervention in the event of a blowout, including the arrangements for drilling relief wells 

and any other measures proposed. The early intervention methods of the third 

requirement could actually include the surface and subsea containment resources that 

BOEMRE announced in NTL 2010-N10, which states that BOEMRE will begin reviewing to 

ensure that the measures are adequate to promptly respond to a blowout or other loss of 

well control.

• responsibilities of all Anadarko and contract personnel to report any observed discharge 

from known or unknown sources;

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

• Contact information for alerting the spill management team complete with names, phone 

numbers, and locations.

In the event of a WCD, Anadarko has access to surface and subsea response/containment 

capabilities that could be implemented through various organizations under contract. 

Anadarko's primary spill response equipment provider is Clean Gulf Associates (CGA). 

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore 

areas. These vessels have oleophilic brush pack skimming systems operating in troughs built 

into the hulls; below deck storage; and marine electronics packages including marine, aircraft 

and company frequency radios, radar, moving map plotters, GPS, satellite phone, and depth 

finders. CGA also offers nine Fast Response Systems staged throughout the Gulf of Mexico 

available for offshore use.

The CGA high-volume open sea skimmer (HOSS) barge consists of a skimming system built into 

an oil recovery barge. There are four 1,000-bbl recovered oil storage tanks built into the hull 

where oil can be separated and offloaded. Skimming operations are conducted from the control 
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room overlooking the skimmer deck. The estimated daily recovery capacity for the HOSS barge 

is approximately 43,000 bbl.

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

Koseq skimming arms and two Aqua Guard skimmers. In addition, an x-band radar/infrared 

tracking system is installed on the HOSS barge.

Anadarko also has a contract with National Response Corporation (NRC) for additional spill 

response equipment. NRC has a dedicated fleet for the Gulf of Mexico and has additional 

available equipment staged throughout the U.S. NRC oil spill response vessels include the 

Admiral, Energy, and Liberty; their oil spill response barges Defender and Valiant are equipped 

with spill containment and recovery gear to respond on request.

NRC's supplemental offshore skimming systems are stored on trailers as units consisting of 

skimmers, boom, and hydraulic power sources in various locations. Units can be mobilized to a 

staging area and loaded onto a supplemental offshore vessel. Vessels of Opportunity will be 

needed for deployment.

Anadarko also is a member of the Marine Well Containment Company (MWCC). 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 to be used in depths up to 

3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day (BLPD) 

(and 120 million standard cubic feet per day [MMSCFD] of gas) with potential for expansion.

In addition, Anadarko is a member of the Helix Well Containment Group (HWCG), a part of the 

Helix Fast Response System (HFRS), and has available all the common response equipment and 

services of the HWCG group. Anadarko’s membership allows access to subsea well containment 

and well shut-in equipment including the Q4000 and Helix Producer I vessels to facilitate control 

and containment of spills. At full production capacity, the HFRS can handle up to approximately 

55,000 BOPD; 70,000 BLPD; and 95 MMSCFD of gas at 10,000 psi in water depths to 2,438 m 

(8,000 ft). HWCG also can provide a 10,000- or 15,000-psi dual ram capping stacks, in addition 

to those available through MWCC.

See EP Section H for a detailed description of Anadarko’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 are discussed briefly below along with a 

hydrogen sulfide (H2S) release. There are no other site-specific issues raised by well drilling 

proposed in this EP.

Chemical Spills. Chemicals are stored and used to condition drill muds and during production 

and in well completions, stimulation, and workover procedures. The relative quantity of their 

use is reflected in the largest volumes spilled. Completion fluids are the largest quantity used 

and comprise the largest releases. Between 5 and 15 chemical spills are anticipated each year, 

with the majority being <50 bbl in size. The most common chemicals spilled are methanol, 
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ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater 

operations where gas hydrates tend to form. Spill volumes are anticipated to remain about the 

same, but spill frequency can be expected to decrease because of advances in subsea processing 

(BOEMRE, 2011a,b).

Riser Disconnect SBM Spills. In deepwater drilling, SBMs are preferred over petroleum oil-based 

muds (OBMs) due to the superior environmental properties of SBMs. The synthetic base fluid 

used in SBMs are less toxic to the marine environment and have the potential to biodegrade. 

SBMs have been used in the Gulf of Mexico since the mid-1990’s, and between 5 and 20 SBM 

releases are anticipated each year as a result of offshore drilling programs. The majority of 

these releases are <50 bbl in size, but accidental riser disconnects may result in the release of 

medium (238 to 2,380 bbl) to large (>2,381 bbl) quantities of drilling fluids. Riser disconnect 

accidents are of particular concern when SBMs are in use (BOEMRE, 2011c).

Vessel Collisions. BOEMRE data show that from 1996 to 2009 there were 226 OCS-related 

collisions. Most collision mishaps are the result of service vessels colliding with platforms or 

vessel collisions with pipeline risers. Approximately 10% of vessel collisions with platforms in 

the OCS 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 BOEMRE (2011a), vessel collisions 

occasionally occur during routine operations. Some of these collisions have caused spills of 

diesel fuel or chemicals. Anadarko will comply with all USCG- and BOEMRE-mandated safety 

requirements to minimize the potential for vessel collisions.

Loss of Well Control. A loss of well control is the uncontrolled flow of a reservoir fluid that may 

result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is 

a broad term that includes very minor up to the most serious well control incidents, while 

blowouts are considered to be a subset of more serious incidents with greater risk of oil spill or 

human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling 

fluid or loss of oil. Anadarko has a robust system in place to prevent loss of well control. 

Measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and 

early intervention in the event of a blowout are described in EP Section H as required by 

NTL 2010-06. The potential for a loss-of-well-control event will be minimized by adhering to the 

requirements of applicable regulations such as the Interim Final Drilling Safety Rule and 

NTL 2010-N10, which specify additional safety measures for OCS activities. 

H2S Release. Pursuant to 30 CFR 250.490(c), Anadarko is requesting in the EP that the BOEMRE 

Regional Supervisor, Field Operations, classify the area in the proposed drilling operations as an 

area where H2S is absent. Based on this, no further discussion of H2S is warranted. 
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B. Affected Environment

The lease area is in the central Gulf of Mexico, 120 miles (194 km) from the nearest shoreline, 

and 131 miles (211 km) from the onshore support base at Port Fourchon, Louisiana (Figure 1).

Based on the Geohazard Survey (Geoscience Earth & Marine Services, Inc. [GEMS], 2003) and 

Site Clearance Letter (GEMS, 2011) water depth at the wellsite is 1,367 m (4,484 ft) (Figure 2). 

There is no evidence of significant seafloor or subsurface faulting, fluid expulsion features, or 

high-density deepwater benthic communities near the wellsite (GEMS, 2011).

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). 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.

The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the 

oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea 

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

Group, 2010a,b,c). Despite limited information on the water quality of deep water, it is clear 

that the condition of the offshore waters of the Gulf of Mexico was altered by the Macondo 

event. Various monitoring efforts and environmental studies are in progress, but it is not 

currently possible to precisely estimate the long-term impacts the spill will have on offshore 

water quality (BOEMRE, 2011a,b).

The lease area is located approximately 178 miles (287 km) southwest of the Macondo spill site. 

Based on an analysis of satellite imagery (ESRI, 2010), the surface slick did not extend over the

lease area and there is no indication that water quality in the lease area was affected. Prior to 

the Macondo incident, water quality in deep, offshore waters of the Gulf of Mexico was 

expected to be good, with low levels of contaminants (Kennicutt, 2000). Based on the 

information currently available, there is no reason to expect any change in water quality 

conditions in the lease area from those predicted in the recent lease sale EISs (MMS, 2007b, 

2008; BOEMRE, 2011a,b).
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Figure 2. Bathymetric map of the lease area showing proposed well surface locations. 
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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, 2011a,b) as well as the 

environmental assessment for Gulf of Mexico deepwater operations and activities (MMS, 2000). 

The information in these documents is incorporated by reference. Potential site-specific issues 

are addressed in this section.

C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site-specific air quality data for the project area due to the distance from shore. 

Because of the distance from shore-based pollution sources and the lack of sources offshore, air 

quality at the wellsite 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 noted earlier, based on calculations made pursuant to applicable regulations, emissions from 

drilling activities are not expected to be significant as they are below exemption levels. 

Therefore, the only potential effects to air quality would be from routine air pollutant emissions, 

a small fuel spill, and a large oil spill (WCD).

BOEMRE has reexamined the analysis for air quality presented in 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 potential impacts on air quality presented in 

previous lease sale EISs (BOEMRE, 2011a,b).

Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant 

emissions will result from the drilling rig operations and helicopters and service vessels. These 

emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels 

occurs primarily on diesel-powered generators, pumps, or motors and from lighter fuel motors. 

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

and CO. Emissions of pollutants into the atmosphere from these activities are not projected to 

have significant effects on onshore air quality because of the prevailing atmospheric conditions, 

emission rates and heights, and resulting pollutant concentrations. As the BOEMRE found in the 

lease sale EISs, the incremental contribution of activities similar to Anadarko’s proposed 

activities to the cumulative impacts is not significant and will not cause or contribute to a 

violation of any National Ambient Air Quality Standard (NAAQS) (MMS, 2007b, 2008). Since the 

BOEMRE completed the lease sale EISs, the USEPA has adopted a new short-term NAAQS for 

nitrogen dioxide. The standard has not yet been implemented in the Gulf Coast states, but 

given the levels of expected emissions and the distance of the project from shore, emissions 

from the activities described in Anadarko’s proposed EP are not likely to contribute to violations 

of any NAAQS onshore.
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Carbon dioxide (CO2) and methane (CH4) emissions from the project would constitute a small 

incremental contribution to greenhouse gas emissions from all OCS activities. According to the 

Programmatic EIS (MMS, 2007a), estimated CO2 emissions from all OCS activities in the 

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

fuel combustion. Greenhouse gas emissions may contribute to climate change, with important 

effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea level 

rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this 

proposed project represent a negligible contribution to the total greenhouse gas emissions from 

reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any 

of the climate change impacts evaluated in the lease sale EIS (MMS, 2007b) or Programmatic EIS 

(MMS, 2007a).

Due to the distance from shore, routine operations in the project area are not expected to have 

any impact on air quality conditions along the coast, including nonattainment areas. As noted in 

the lease sale EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central

Gulf of Mexico Planning Area are projected to have minimal impacts to onshore air quality 

because of the prevailing atmospheric conditions, emission heights, emission rates, and the 

distance of these emissions from the coastline. The Air Quality Emissions Report 

(see EP Section G) prepared in accordance with BOEMRE requirements shows that the projected 

emissions are below exemption levels; therefore, according to 30 CFR 250.303, the emissions 

will not significantly affect the air quality of the onshore area for any of the criteria pollutants. 

No further analysis or control measures are required.

The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is 

designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air 

quality area. The BOEMRE is required to notify the National Park Service (NPS) and U.S. Fish and 

Wildlife Service (USFWS) if emissions from proposed projects may affect the Breton Class I area.

Additional review and mitigation measures may be required for sources within 186 miles 

(300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering 

agencies (NPS, 2010). The lease area is approximately 178 miles (287 km) from the Breton 

Wilderness Area, so air quality impacts on the Wilderness Area are not expected. Anadarko will 

comply with all BOEMRE requirements regarding air emissions.

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, 2011a,b). 

The probability of a small spill would be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will 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.
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A small fuel spill would not affect coastal air quality because the spill would not be expected to 

make landfall or reach coastal waters prior to breaking up (see Section A.9.2).

Impacts of a Large Oil Spill (WCD)

Potential impacts of a large oil spill on air quality are expected to be consistent with those 

analyzed and discussed in recent lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a,b).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through 

evaporation from the slick. The extent and persistence of impacts would depend on the 

meteorological and oceanographic conditions at the time and the effectiveness of spill response 

measures. Realtime wind and current data from the project area would be available at the time 

of a spill and would be used to assess the fate and effects of VOCs released. Additional air 

quality impacts could occur if response measures included in-situ burning of the floating oil. 

Burning would generate a plume of black smoke and result in emissions of NOx, SOx, CO, and 

PM, as well as greenhouse gases. However, in situ burning would occur only after authorization 

from the USEPA.

Due to the lease area location (120 miles [194 km]) from the nearest shoreline, most air quality 

impacts would occur in offshore waters with minimal chance to affect onshore air quality.

C.1.2 Water Quality

There are no site-specific water quality data for the lease area. Due to the lease location in 

deep, offshore waters, water quality is expected to be good, with low levels of contaminants. As 

noted in 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. 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 178 miles (287 km) from the Macondo spill site. Based 

on the general circulation pattern seen in the Gulf of Mexico and satellite imagery (ESRI, 2010), 

the surface slick from that discharge did not extend over the lease area during the spill. The 

existing water quality in the lease area is not expected to have been affected by the Macondo 

release.

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

a small fuel spill and a large oil spill (WCD).

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 for recycling and/or disposal in an approved facility. Cuttings wetted with SBMs will 

be discharged to the seafloor in accordance with the NPDES permit. 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). 
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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. Rainwater that falls on uncontaminated 

areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on 

the drilling rig deck and other areas such as chemical storage areas and places where equipment 

is exposed will be collected and oil and water separated to meet NPDES permit requirements. 

Based on adherence to permit limits and applicable regulations, little or no impact on water 

quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and 

uncontaminated cooling water, fire water, and ballast water are expected to be diluted rapidly,

resulting in little or no impact on water quality.

Impacts of a Small Fuel Spill

Potential impacts of a small spill on water quality are expected to be consistent with those 

analyzed and discussed in recent EISs (MMS, 2007b, 2008; BOEMRE, 2011a,b). The probability 

of a small spill would be minimized by Anadarko’s preventative measures during routine 

operations, including fuel transfer. In the unlikely event of a spill, implementation of Anadarko’s 

OSRP will potentially 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. 

Diesel is so light that it is not possible for the oil to sink and pool on the seafloor. Diesel 

dispersed in the water column can adhere to suspended sediments, but this generally occurs 

only in coastal areas with high suspended solid loads (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).
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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). A large spill would affect 

water quality by producing a slick on the water surface and increasing the concentrations of 

petroleum hydrocarbons and their degradation products. The extent and persistence of impacts 

would depend on the meteorological and oceanographic conditions at the time and the 

effectiveness of spill response measures. Most of the oil would be expected to form a slick at 

the surface, although new information from the Macondo spill indicates that plumes of 

submerged oil droplets can be produced when subsea dispersants are applied at the wellhead 

(Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants 

would be applied only after approval from the USEPA. Small droplets in the water may adhere 

to suspended sediment and be removed from the water column (Operational Scientific Advisory 

Team [OSAT], 2010).

Due to the lease area location (120 miles or 194 km from the nearest shoreline), it is expected 

that most water quality impacts would occur in offshore waters, especially in the event of a spill 

lasting less than 30 days (Table 3). 

C.2 Seafloor Habitats and Biota

Water depth at the proposed BHL is 1,367 m (4,484 ft). The seafloor generally dips toward the

west-southwest at about 0.7° at the proposed wellsite GC 727 #002. The seafloor in this area is 

irregular as a result of the numerous fault scarps and the deformation of the shallow 

overburden and the near-surface sediments are expected to be normally consolidated clays

forming a drape over the area. The immediate regions around the proposed well locations have 

no evidence of seafloor instability within 610 m (2,000 ft) of the wellsite. No areas of possible 

hard bottom or microseepages were seen within 610 m (2,000 ft) of the wellsite (GEMS, 2011). 

Based on the absence of hard bottom areas detected by side-scan sonar during the Site 

Clearance Survey, the seafloor is expected to consist mainly of soft bottom communities. The 

Site Clearance Survey did not identify any features that could support high-density deepwater 

benthic communities within 610 m (2,000 ft) of the wellsite. No areas of gaseous sediments or 

possible hydrocarbon seepage were defined in the study area, and the presence of 

chemosynthetic communities is considered low (GEMS, 2011). 

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 collected at four stations. The closest stations B1 and GKF were 

located 37 and 43 miles (60 and 69 km), respectively, from the lease area. These two stations 

were in greater water depths (2,256 and 2,460 m [7,402 and 8,071 ft]) than the lease area. 

Station C4 was located at a greater distance from the lease area (64 miles [103 km]) but in a 

water depth (1,446 m [4,744 ft]) similar to that of the lease area. Station MT4, located 

107 miles (172 km) from the lease area, was in a water depth of 1,403 m (4,603 ft), similar to 

that of the lease area and is included for comparison. Sediments at the stations closest to the 

lease area (B1 and GKF) were predominantly clay (52.7% to 59.1%), with 37.4% to 44.5% silt.
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Table 4. Benthic community data from stations near the lease area and in greater water depths 

and more distant stations in more similar depths sampled during the Northern Gulf of 

Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted from: 

Wei, 2006; Rowe and Kennicutt, 2009).

Station

Distance to 

Lease Area

(miles)

Water Depth

(m)

Abundance

Meiofauna

(individuals/m2)

Macroinfauna

(individuals/m2)

Megafauna

(individuals/ha)

B1 37 2,256 157,417 1,446 252

GKF 43 2,460 84,348 737 --

C4 64 1,446 273,585 3,045 743

MT4 107 1,403 246,058 3,262 1,548

Meiofaunal and megafaunal abundances from Rowe and Kennicutt (2009); macroinfaunal abundance 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 (1,367 m [4,484 ft]) typically range from 

approximately 246,000 to 273,000 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 2,500 individuals/m2

, or greater than the numbers for the closest locations 

listed in Table 4.

Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of 

Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) 

recognized four depth-dependent faunal zones (1 through 4), two of which are divided 

horizontally. The lease area is in Zone 3W. This zone, with stations in water depths of 

1,875 to 3,008 m (6,152 to 9,869 ft), had the polychaetes Levinsenia uncinata, Paraonella 

monilaris, and Tachytrypane sp. A; the bivalve Heterodonta sp.; and the isopod 

Macrostylis “256” as the most abundant taxa.

Megafaunal densities from nearby Station B1 was 252 individuals/ha (Table 4). Densities of 

200 to 1,600 individuals/ha were reported from other stations located at a depth range similar 

to that of the lease area. 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 benthic communities are physical disturbance to the seafloor, effluent 

discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout 
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at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel 

would float and dissipate on the sea surface.

Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships or semisubmersibles 

disturb the seafloor only around the wellbore (SHL) 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). 

The areal extent of these impacts from the DP rig will 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). Impacts 

from the physical disturbance of the seafloor during this project will have no significant impact 

on soft bottom benthic communities in the region.

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 the wellsite. The fate and effects of SBM cuttings have been 

reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of 

Mexico by Continental Shelf Associates, Inc. (2004, 2006). In general, washed cuttings with 

adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas 

of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic 

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

concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may be 

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 the 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.
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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; 

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

carbonates created by chemosynthetic communities.

The nearest known chemosynthetic community site is located approximately 26 miles (41 km) 

north of the lease area in GC 994. The nearest identified deepwater coral community is located 

in GC 600, approximately 16 miles (26 km) east-northeast of the lease area.

No mounds, depressions, or hard bottom features occur within a 2,000-ft radius around the 

proposed wellsite. Therefore, the potential for high-density chemosynthetic communities 

within 2,000 ft of the proposed location is low (GEMS, 2011).

IPFs potentially affecting high-density deepwater benthic communities include physical 

disturbance of 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 fuel would float and dissipate on the sea surface.
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Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships or semisubmersibles 

disturb the seafloor only around the wellbore (SHL) 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). 

The areal extent of these impacts from the DP rig will be small, and NTL 2009-G40 requires that 

high-density deepwater benthic communities and features or areas that could support 

high-density chemosynthetic communities, or deepwater corals communities be avoided. Based 

on the GEMS (2011) report, there will be no impacts on chemosynthetic or deepwater coral 

communities from this project.

Impacts of Effluent Discharges

The Site Clearance Survey (GEMS, 2011) did not identify any features that could support 

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

locations, and the presence of chemosynthetic communities in the lease area is considered 

remote. Monitoring programs on the Gulf of Mexico continental slope have shown that benthic 

impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft) of the 

wellsite, although detectable deposits may extend beyond this distance (Continental Shelf 

Associates, Inc., 2004, 2006; Neff et al., 2005). Because of the water depth of the lease area, 

drilling discharges would be expected to result in thinner, more diffuse accumulations on the 

seafloor than those documented in the literature. Although small amounts of cuttings particles 

may reach areas inhabited by high-density deepwater benthic communities, the discharges are 

not expected to result in significant impacts to these communities.

Impacts of a Large Oil Spill (WCD)

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect 

benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical 

impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill 

location. However, during the Macondo spill, subsurface plumes were reported at a water 

depth of about 1,100 m (3,600 ft), extending at least 22 miles (35 km) from the wellsite and 

persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently 

resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the 

behavior and impacts of subsurface plumes are not well known, a subsurface plume could have 

the potential to contact high-density deepwater benthic communities beyond the 300-m 

(984-ft) radius estimated by MMS (2007a, 2008), depending on its extent, trajectory, and 

persistence. Potential impacts on sensitive resources would be an integral part of the decision 

and approval process for the use of dispersants, and such approval would be obtained from the 

USEPA prior to the use of dispersants.

The biological effects and expected fate of the oil remaining in the Gulf of Mexico from the 

Deepwater Horizon blowout are still unknown due to the depth and magnitude of this event. 

Hazen et al. (2010) reported changes in plume hydrocarbon composition with distance from the 

source. Incubation experiments with environmental isolates demonstrated faster than expected 

hydrocarbon biodegradation rates at 5 °C. Based on these results, Hazen et al. (2010) suggested 

the potential exists for intrinsic bioremediation of the oil plume in the deep water column 

without substantial oxygen drawdown.
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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 to 40 m (50 to 130 ft) was covered by what 

appeared to be a brown substance. Out of 40 large corals, 90% were heavily affected and 

showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had 

a colony of stony corals similarly affected and partially covered with a similar brown substance. 

Until laboratory analyses are conducted, scientists cannot be certain what caused the impacts. 

Sediment and coral samples were collected with a remotely operated vehicle and brought to the 

surface for analyses. Further testing will also determine if the substance is oil, and if so, 

whether it is consistent with the release from the Macondo spill.

C.2.3 Designated Topographic Features

The block is not within or near a designated topographic feature or a no-activity zone as 

identified in NTL 2009-G39. The nearest designated topographic feature is Ship Shoal South in 

Ewing Bank (EW) Block 947, located 112 miles (181 km) north of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause 

impacts to designated topographic features due to the distance from the lease area. A small 

fuel spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor 

features. If a subsurface plume were to occur, impacts on these features would be unlikely due 

to the distance and the difference in water depth. Near-bottom currents in the region are 

predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume 

up onto the continental shelf edge.

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 is Main Pass Block 290, which lies 194 miles (313 km) 

northeast from the lease area.
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There are no IPFs associated with either routine operations or accidents that could cause 

impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small 

fuel spill would float on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor 

features. If a subsurface plume were to occur, impacts on these features would be unlikely due 

to the distance and the difference in water depth. Near-bottom currents in the region are 

predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume 

up onto the continental shelf edge.

C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which applies to 

Eastern Gulf of Mexico Planning Area leases in water depths of 100 m (328 ft) or less. The 

nearest block covered by the live bottom stipulation, as defined by NTL 2009-G39, is 

Destin Dome Block 573, approximately 234 miles (377 km) northeast of the lease area.

There are no IPFs associated with either routine operations or accidents that could cause 

impacts to eastern Gulf live bottom areas due to the distance from the lease area. A small fuel 

spill would float and dissipate on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor 

features. If a subsurface plume were to occur, impacts on these features would be unlikely due 

to the distance and the difference in water depth. Near-bottom currents in the region are 

predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume 

up onto the continental shelf.

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

This section discusses species listed as endangered or threatened under the Endangered Species 

Act (ESA). In addition, it includes all marine mammal species in the region, which are protected 

under the Marine Mammal Protection Act (MMPA).

Endangered or threatened species that may occur in the project area and/or along the northern 

Gulf Coast are listed in Table 5. The table also indicates the location of critical habitat 

(if designated in the Gulf of Mexico). Critical habitat is defined as (1) specific areas within the 

geographical area occupied by the species at the time of listing, if they contain physical or 

biological features essential to conservation, and those features may require special 

management considerations or protection; and (2) specific areas outside the geographical area 

occupied by the species if the agency determines that the area itself is essential for 

conservation. The National Marine Fisheries Service (NMFS) has jurisdiction for ESA-listed 

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

ESA-listed birds and the West Indian manatee.
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Table 5. Federally-listed endangered and threatened species 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 X X None

Green turtle Chelonia mydas T, Eb X X None

Leatherback turtle Dermochelys coriacea E X X None

Hawksbill turtle Eretmochelys imbricata E X X None

Kemp’s ridley turtle Lepidochelys kempii E X X None

Birds

Piping Plover Charadrius melodus T -- X

Coastal Texas, Louisiana, 

Mississippi, Alabama, 

and Florida (Panhandle)

Whooping Crane Grus americana E -- X

Coastal Texas 

(Aransas National 

Wildlife Refuge)

Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T -- X

Coastal Louisiana, 

Mississippi, Alabama, 

and Florida (Panhandle)

Smalltooth sawfish Pristis pectinata E -- X Southwest Florida and 

the Florida Keys

Invertebrates

Elkhorn coral Acropora palmata E -- X Flower Garden Banks

Terrestrial Mammals

Beach mice (Alabama, 

Choctawhatchee, 

Perdido Key, St. Andrew)

Peromyscus polionotus E -- X Alabama and Florida 

(Panhandle) beaches

Abbreviations: E = endangered; T = threatened. a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely

to be present in the lease area. b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

As mandated by the ESA, BOEMRE 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, BOEMRE requested to reinitiate an ESA consultation with both 
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NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on 

24 September 2010, and the USFWS responded with a letter to BOEMRE on 27 September 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 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

(BOEMRE, 2011a). The existing consultation recognizes that BOEMRE-required mitigations and 

other reasonable and prudent measures should reduce the likelihood of impacts from all 

BOEMRE-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 mice. Critical habitat has been designated for all of these species as indicated in Table 5

and discussed in individual sections.

Two other coastal species (Bald Eagle and Brown Pelican) are discussed in the MMS (2007b) 

lease sale EIS are no longer listed as endangered or threatened. These species are discussed

here under Coastal and Marine Birds.

The sperm whale and five species of sea turtles are the only endangered or threatened species 

likely to occur at or near the lease area. No critical habitat has been designated for these 

species in the Gulf of Mexico.

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.

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 Gulf of Mexico Loop Current (Jochens et al., 2008). 

Sperm whale populations in the north-central Gulf of Mexico are present there throughout the 

year (Davis et al., 2000). Results of a multi-year tracking study show female sperm whales 

typically concentrated along the upper continental slope between the 200- and 1,000-m 

(656- and 3,280-ft) depth contours (Jochens et al., 2008). Male sperm whales were more 

variable in their movements and were documented in water depths greater than 3,000 m 

(9,843 ft). Generally, groups of sperm whales sighted in the Gulf of Mexico during the 

MMS-funded Sperm Whale Seismic Study (SWSS) consisted of mixed-sex groups comprising 

adult females and immatures, and groups of bachelor males. Typical group size for mixed 

groups was 10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit 

through the vicinity of the lease area. Movements of satellite-tracked individuals suggest that 
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this area of the Gulf continental slope is within the home range of the Gulf of Mexico population 

(within the 95% utilization distribution) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support 

vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill 

(WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid 

dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the 

mobility of these marine mammals. Compliance with NTL 2007-G03 will minimize the potential 

for marine debris-related impacts on sperm whales.

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

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

that could represent an impediment to recovery,” and 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, 2011a,b).

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb sperm whales. Sperm whales 

appear to have good low-frequency hearing, but the available data do not indicate a consistent 

response to anthropogenic noise (Jochens et al., 2008). Noise 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 are not identified as IPFs for sperm whales in recent lease 

sale EISs (MMS, 2007b, 2008) or the NMFS (2007) Biological Opinion.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales, and there is also a risk of vessel 

strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a). Data 

concerning the frequency of vessel strikes are presented in a recent lease sale EIS 

(MMS, 2007b). To reduce the potential for vessel strikes, MMS issued NTL 2007-G04, which 

recommends protected species identification training and that vessel operators and crews 

maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid 

striking protected species, and requires operators to report sightings of any injured or dead 

protected species. When whales are sighted, vessel operators and crews are required to 
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attempt to maintain a distance of 91 m (300 ft) or greater whenever possible. Vessel operators 

are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large 

assemblages of cetaceans are observed near an underway vessel, when safety permits. 

Compliance with this 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 2007-G04, 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 level of the population. With implementation of the vessel 

strike avoidance measures requirement to maintain a distance of 90 m (295 ft) from sperm 

whales, the NMFS concluded that the potential for harassment of sperm whales would be 

reduced to discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) 

documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an 

altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during 

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.

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 Anadarko’s preventative measures during 

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

Anadarko’s OSRP will mitigate and lessen the potential for impacts on sperm whales. Given the 

open ocean location of the lease area, the duration of a small spill and opportunity for impacts 

to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 
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of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and 

noise of response vessels and aircraft (Marine Mammal Commission [MMC], 2010). However, 

due to the limited areal extent and short duration of water quality impacts from a small fuel 

spill, as well as the mobility of sperm whales, no significant impacts would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs 

(MMS, 2007b, 2008) and by 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, 2010). Direct physical and physiological effects can include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from 

the activities and noise of response vessels and aircraft. Complications of the above may lead to 

dysfunction of immune and reproductive systems, physiological stress, declining physical 

condition, and death. Behavioral responses can include displacement of animals from prime 

habitat, disruption of social structure, changing prey availability and foraging distribution and/or 

patterns, changing reproductive behavior/productivity, and changing movement patterns or 

migration (MMC, 2010).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury 

or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the 

potential for striking or disturbing these animals.

C.3.2 West Indian Manatee (Endangered)

Most of the manatee population is located in peninsular Florida (USFWS, 2001). Manatee 

sightings in Louisiana have 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, as the lease 

area is approximately 120 miles (194 km) from the nearest shoreline (Louisiana). As explained in 

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

prior to breaking up. Compliance with NTL 2007-G03 will minimize the potential for marine 

debris-related impacts on manatees.
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Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel 

strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). To 

reduce the potential for vessel strikes, MMS issued NTL 2007-G04, which recommends 

protected species identification training and that vessel operators and crews maintain a vigilant 

watch for marine mammals and slow down or stop their vessel to avoid striking protected 

species, and requires operators to report sightings of any injured or dead protected species. 

Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant 

impacts on manatees are expected.

Helicopter traffic also has the potential to disturb manatees. Rathbun (1988) reported that 

manatees were disturbed more by helicopters than by fixed-wing aircraft; however, the 

helicopter was flown at a relatively low altitude of 20 to 160 m (66 to 525 ft). Helicopters used 

in support operations maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 

305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over 

populated areas and sensitive habitats such as wildlife refuges and park properties. This 

mitigation measure will minimize the potential for disturbing manatees, and no significant 

impacts are expected.

Impacts of a Large Oil Spill (WCD)

In the event that manatees were exposed to oil, effects could include direct impacts from oil 

exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, 

noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin 

irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; 

inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey 

(or contaminated vegetation, in the case of manatees); and stress from the activities and noise 

of response vessels and aircraft. Complications of the above may lead to dysfunction of immune 

and reproductive systems, physiological stress, declining physical condition, and death. 

Behavioral responses can include displacement of animals from prime habitat, disruption of 

social structure, changing prey availability and foraging distribution and/or patterns, changing 

reproductive behavior/productivity, and changing movement patterns or migration 

(MMC, 2010).

In the event that a large spill reached coastal waters where manatees were present, the level of 

vessel and aircraft activity associated with spill response could disturb manatees and potentially 

result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate 

in accordance with NTL 2007-G04 to reduce the potential for striking or disturbing these 

animals, and therefore no significant impacts are expected.

C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right 

whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare 

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 
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contact with any project activities, either routine operations or accidents. NMFS did not include 

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 two 

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

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

dolphin (Stenella coeruleoalba). 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 2007-G03 will 

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

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most 

odontocetes (toothed whales and dolphins) use higher frequency sounds than the dominant low

frequencies produced by OCS drilling activities (Richardson et al., 1995). Noise 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).

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, MMS issued NTL 2007-G04, 

which recommends protected species identification training and that vessel operators and 

crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to 

avoid striking protected species, and requires operators to report sightings of any injured or 

dead protected species. Vessel operators and crews are required to attempt to maintain a 

distance of 91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when small 

cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must 

attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes 

in direction until the cetacean has left the area. Vessel operators are required to reduce vessel 

speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are 

observed near an underway vessel, when safety permits. Compliance with NTL 2007-G04 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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Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008),

and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For 

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

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of Anadarko’s OSRP is expected to 

lessen the potential for impacts on marine mammals. EP Section H provides detail on spill 

response measures, along with a summary of those measures in this EIA. Given the open ocean 

location of the lease area, the limited duration of a small spill and response efforts, it is 

expected that any impacts would be brief and minimal.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and 

noise of response vessels and aircraft (MMC, 2010). However, due to the limited areal extent 

and short duration of water quality impacts from a small fuel spill, as well as the mobility of 

marine mammals, no significant impacts would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in MMS (2000, 2007b, 2008). For this 

EP, there are no unique site-specific issues. Impacts of oil spills on marine mammals can include 

direct impacts from oil exposure, as well as indirect impacts due to response activities and 

materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and 

physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of 

skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) 

directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and 

stress from the activities and noise of response vessels and aircraft. Complications of the above 

may lead to dysfunction of immune and reproductive systems, physiological stress, declining 

physical condition, and death. Behavioral responses can include displacement of animals from 

prime habitat, disruption of social structure, changing prey availability and foraging distribution 

and/or patterns, changing reproductive behavior/productivity, and changing movement 

patterns or migration (MMC, 2010).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb marine mammals and potentially result in vessel strikes, entanglement, or other 

injury or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce 

the potential for striking or disturbing these animals, and therefore no significant impacts are 

expected.
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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 loggerhead turtle (Caretta caretta) is 

currently a threatened species; however, in March 2001, NMFS and USFWS proposed to list the 

Northwest Atlantic Ocean population of loggerhead turtles as endangered (75 FR 12598). 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 5-Year Program. As a result of this new 

information, BOEMRE reinitiated ESA Section 7 consultation on the existing Gulf of Mexico lease 

sale EIS with NMFS and the USFWS on 30 July 2010. The NMFS responded with a letter to 

BOEMRE on 24 September 2010, and the USFWS responded with a letter to BOEMRE on 

27 September 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 (BOEMRE, 2011a). 

BOEMRE (2011a,b) 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 

and, to a lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant 

nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR;

• Green and leatherback turtles – Green and leatherback turtles infrequently nest on Florida 

Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2011);

• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, 

Tamaulipas, Mexico (NMFS et al., 2010). Kemp’s ridley turtles typically do not nest 

anywhere near the project area, although there have been occasional reports of Kemp’s 

ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support 

vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill 

(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 2007-G03 will minimize the potential for marine debris-related impacts on 

sea turtles.
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Impacts of Drilling Rig Presence, Noise, and Lights 

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that 

may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include 

behavioral disruption and temporary or permanent displacement from the area near the sound 

source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures 

(Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced 

during routine operations. Helicopters and service vessels may also affect sea turtles due to 

machinery noise and/or visual disturbances. The most likely impacts would be short-term 

behavioral changes such as diving and evasive swimming, disruption of activities, or departure 

from the area. Due to the limited scope and short duration of drilling activities, these 

short-term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 

1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they 

are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The 

NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are 

insignificant.

Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles, and there is also a risk of vessel 

strikes. Data show that vessel traffic is one cause of sea turtle mortality in the Gulf of Mexico 

(Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in 

clear weather, they can be difficult to spot from a moving vessel when resting below the water 

surface, during nighttime, or during periods of inclement weather. To reduce the potential for 

vessel strikes, MMS issued NTL 2007-G04, which recommends protected species identification 

training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow 

down or stop their vessel to avoid striking protected species, and requires operators to report 

sightings of any injured or dead protected species. When sea turtles are sighted, vessel 

operators and crews are required to attempt to maintain a distance of 45 m (150 ft) or greater 

whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as 

well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, 

helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. 

This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are 

expected.

Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008) and 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 Anadarko’s preventative measures during fuel 

transfer. In the unlikely event of a spill, implementation of Anadarko’s OSRP is expected to

minimize potential impacts on sea turtles. EP Section H provides detail on spill response 

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 
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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 120 miles (194 km) from the nearest shoreline (Louisiana). As explained in 

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

prior to breaking up.

Impacts of a Large Oil Spill (WCD)

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as 

indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and 

dispersants). Direct physical and physiological effects can include skin irritation, inflammation, 

or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and 

smoke (e.g., from in situ burning of oil); ingestion of oil (and dispersants) directly or via 

contaminated food; and stress from the activities and noise of response vessels and aircraft. 

Complications of the above may lead to dysfunction of immune and reproductive systems, 

physiological stress, declining physical condition, and death. Behavioral responses can include 

displacement of animals from prime habitat, disruption of social structure, changing food 

availability and foraging distribution and/or patterns, changing reproductive 

behavior/productivity, and changing movement patterns or migration. In the unlikely event of a 

spill, implementation of Anadarko’s OSRP is expected to minimize the potential for these types 

of impacts on sea turtles. EP Section H provides detail on spill response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that 

sea turtles show no avoidance behavior when they encounter an oil slick, and any sea turtle in 

an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them 

at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface 

over time, which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

Spilled oil reaching sea turtle nesting beaches could have effects on nesting sea turtles and egg 

development (NMFS, 2007). An oiled beach could affect nest site selection or result in no 

nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings 

are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil 

residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired 

movement and normal bodily functions (NMFS, 2007).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or 

stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the 

potential for striking or disturbing these animals, and therefore no significant impacts are 

expected.
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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).

Impacts of a Large Oil Spill (WCD)

The lease area is 121 miles (194 km) from the nearest shorelines inhabited by Piping Plovers 

(Figure 3). The revised OSRA results (BOEMRE, 2011a) summarized in Section A.9.3 (Table 3) 

predict that during the spring there is a 4% probability that an oil spill from the lease area would 

reach a shoreline designated as critical habitat for the Piping Plover within 10 days. Plovers 

could physically oil themselves while foraging on oiled shores or secondarily contaminate 

themselves through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers 

congregate and feed along tidally exposed banks and shorelines, following the tide out and 

foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, 

especially if spills occur during winter months when plovers are most common along the coastal 

Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on 

beaches and other activities associated with spill cleanup. Anadarko has extensive resources 

available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as 

detailed in the OSRP.

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 

non-migrating population has been reintroduced in central Florida, and another reintroduced 

population summers in Wisconsin and migrates to the southeastern U.S. for the winter. 

Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal 

marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural 

fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent 

islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is 

designated as critical habitat for the species. 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.
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Figure 3. Location of selected environmental features in relation to the lease area.
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Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately 

353 miles (568 km) from its critical habitat designated in the Aransas NWR. The revised OSRA 

modeling (BOEMRE, 2011a) predicts that there is a 3% or less probability that an oil spill 

originating in the lease area would reach the Aransas NWR within 30 days and a 17% probability 

of oil reaching that area in 120 days.

In the event of oil exposure, Whooping Cranes could physically oil themselves while foraging in 

oiled areas or secondarily contaminate themselves through ingestion of contaminated shellfish, 

frogs, and fishes. It is possible that some Whooping Crane deaths could occur. In the event of a 

spill, Anadarko would work with the applicable State and Federal agencies to prevent impacts 

from a spill.

C.3.8 Gulf Sturgeon (Threatened)

The Gulf sturgeon (Acipenser oxyrinchus desotoi) is a threatened fish species that inhabits major 

rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida 

(Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream 

into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to 

Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass 

major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. 

Populations have been depleted or even extirpated throughout this range by fishing, shoreline 

development, dam construction, water quality changes, and other factors (Barkuloo, 1988; 

Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened 

species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in 

Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 

2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the 

Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) to Suwannee Sound, Florida 

(Levy County) (NMFS, 2010b) (Figure 3). A species description is presented in 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).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on Gulf sturgeon are discussed in recent lease sale EISs (MMS, 2007b, 

2008) and by NMFS (2007). For this EP, there are no unique site-specific issues with respect to 

this species.

The lease area is approximately 190 miles (306 km) from the nearest Gulf sturgeon critical 

habitat. The revised OSRA modeling (BOEMRE, 2011a) predicts that a spill in the lease area has 

1% or less probability of contacting any coastal areas inhabited by Gulf sturgeon within 

30 or 120 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, 

ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. 
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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 Smalltooth Sawfish (Endangered)

Smalltooth sawfish (Pristis pectinata) are found in the tropical and subtropical Atlantic Ocean. 

In the Western Atlantic they have historically ranged from New York to Brazil, including the Gulf 

of Mexico and Caribbean Sea. This sawfish primarily occurs in estuarine and coastal habitats 

such as bays, lagoons, and rivers. The smalltooth sawfish was listed as endangered on 

1 April 2003, under the ESA. Its critical habitat consists of two units: the Charlotte Harbor 

Estuary Unit, which comprises approximately 89,621 ha (221,459 ac) of coastal habitat; and the 

Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha (619,013 ac)

of coastal habitat. The two units are located along the southwestern coast of Florida between 

Charlotte Harbor and Florida Bay.

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish. 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 smalltooth sawfish 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).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and 

estuarine species in recent lease sale EISs (MMS, 2007b, 2008) and by the NMFS (2007) in its 

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

smalltooth sawfish.

In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct 

ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through 

the gills. 

C.3.10 Beach Mice (Endangered)

Four subspecies of endangered beach mice (Peromyscus polionotus) occur on the barrier islands 

of Alabama and the Florida Panhandle. They are the Alabama, Choctawatchee, Perdido Key, and 

St. Andrew beach mice. Critical habitat has been designated for all four subspecies; Figure 3

shows the critical habitat combined for all four subspecies. Species descriptions are provided in 

a recent lease sale EIS (MMS, 2007b). 

A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs 

associated with routine project activities that could affect these animals due to the distance 

from shore and the lack of any onshore support activities near their habitat. A small fuel spill in 

the lease area would not affect beach mice because a small fuel spill would not be expected to 

make landfall or reach coastal waters prior to breaking up (see Section A.9.2).
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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 263 miles (423 km) southwest from the nearest beach mouse critical 

habitat. The revised OSRA modeling summarized in Section A.9.3 predicts that a spill in the 

lease area has a 1% or less probability of reaching either the Alabama or Florida shorelines 

inhabited by beach mice within 120 days.

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.3.11 Elkhorn Coral (Endangered) 

Elkhorn coral (Acropora palmata) is found primarily in shallow waters with temperatures ranging 

between 26 °C and 30 °C (79 and 86 °F) and significant water movement. Elkhorn coral was 

once one of the most abundant species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in 

tropical and subtropical waters. In the northern Gulf, elkhorn coral has been found within the 

coral cap region of the Flower Garden Banks National Marine Sanctuary (Flower Garden Banks 

National Marine Sanctuary, 2011).

There are no IPFs associated with routine project activities that could affect this species in the 

northern Gulf. A small fuel spill would not affect elkhorn coral colonies because the oil would 

float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of 

the Flower Garden Banks because of the water depth of the area. Although subsurface plumes 

were reported following the Macondo spill, these plumes resulted from the use of subsea 

dispersants at the seafloor. 

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 
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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).

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 2007-G03 will minimize the potential for marine 

debris-related impacts on birds.

Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent rigs may be exposed to contaminants including air pollutants and routine 

discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over 

water have been known to strike offshore structures, resulting in death or injury (Wiese et al., 

2001; Russell, 2005). Mortality of migrant birds at tall towers and other land-based structures 

has been reviewed extensively, and the mechanisms involved in rig collisions appear to be 

similar. In some cases, migrants simply do not see a part of the rig until it is too late. In other 

cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore 

structures are suitable stopover habitats for most trans-Gulf migrant species, and most of the 

migrants that stop over on rigs probably benefit from their stay, particularly in spring 

(Russell, 2005). Due to the limited scope and short duration of drilling activities 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 
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Mexico also noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors 

to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of 

cloudy and foggy days in the Gulf of Mexico vs. the North Sea. Due to the limited scope and 

short duration of drilling activities proposed in this EP, lighting impacts, collisions, or other 

adverse effects are unlikely, and no significant impacts are expected.

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, 

offshore waters. It is likely that individual birds would experience, at most, only short-term 

behavioral disruption, and the impact would not be significant.

Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in recent EISs (MMS, 2007b, 2008). For this 

EP, there are no unique site-specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will reduce the potential for impacts on marine and pelagic birds. 

EP Section H provides detail on spill response measures. Given the open ocean location of the 

lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects 

including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of 

toxic fumes. Due to the limited areal extent and short duration of water quality impacts from a 

small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in 

prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small 

area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds 

would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine and pelagic birds are discussed in recent EISs (MMS, 2007b, 

2008). For this EP, there are no unique site-specific issues with respect to spill impacts on these 

animals.

BOEMRE has reexamined the 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, 2011a,b).

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 
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seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird 

densities over the open ocean typically are <10 birds/km2

. The number of pelagic birds that 

could be affected in open, offshore waters would depend on the extent and persistence of the 

oil slick.

The recent Macondo spill provides relevant information about the species of pelagic birds that 

may be affected in the event of a large oil spill. Birds that have been treated for oiling include 

several pelagic species such as the Northern Gannet, Magnificent Frigatebird, and Masked 

Booby (International Bird Rescue Research Center, 2010). The Northern Gannet is among the 

species with the largest numbers of birds affected by the spill.

C.4.2 Shorebirds and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been 

discussed previously in Section C.3. Various species of non-endangered birds are also found 

along the northern Gulf Coast, including diving birds, shorebirds, marsh birds, wading birds, and 

waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and 

nesting habitats. Species that breed on beaches, flats, dunes, bars, barrier islands, and similar 

habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull-Billed 

Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is 

presented in recent lease sale EISs (MMS, 2007b, 2008).

The Brown Pelican (Pelecanus occidentalis) was delisted from Federal endangered status in 2009 

(USFWS, 2010c). However, this species is listed as a species of greatest conservation need by 

the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 2011) and as a 

species of special concern by the State of Florida (Florida Fish and Wildlife Conservation 

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 U.S., including coastal habitats along the Gulf of Mexico. The Gulf Coast is 

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

1992).

IPFs potentially affecting shorebirds and coastal nesting birds include support vessel and 

helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely 

to affect shorebirds or coastal nesting birds, as the lease area is 120 miles (194 km) from the 

nearest shoreline. As explained in Section A.9.2, a small fuel spill would not be expected to 

make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2007-G03 will 

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

Impacts of Support Vessel and Helicopter Traffic

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

Louisiana, where shorebirds and coastal nesting birds may be found. These activities could 
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periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands 

that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between 

species and between individuals (Rodgers and Schwikert, 2002). The disturbances will be 

limited to flushing birds away from vessel pathways; known distances are from 20 to 49 m 

(65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard-powered 

boat (Rodgers and Schwikert, 2002). Flushing distances may be similar or less for the support 

vessels to be used for Anadarko’s project, and some species such as gulls are attracted to boats. 

Support vessels will not approach nesting or breeding areas on the shoreline, so disturbances to 

nesting birds, eggs, and chicks is not expected. Vessel operators will use designated navigation 

channels and comply with posted speed and wake restrictions while transiting sensitive inland 

waterways. Due to the limited scope and short duration of drilling activities, any short-term 

impacts are not expected to be biologically significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly 

dependent on the type of aircraft, the bird species, the activities that animals were previously 

engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to 

cause the most intense responses over other human disturbances for some species (Bélanger 

and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91-36D 

recommends that pilots maintain a minimum altitude of 610 m (2,000 ft) when flying over 

noise-sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. 

This is greater than the distance (slant range) at which aircraft overflights have been reported to 

cause behavioral effects on most species of birds studied (Efroymson et al., 2000). With these 

guidelines in effect, it is likely that individual birds would experience, at most, only short-term 

behavioral disruption.

Impacts of Large Oil Spill (WCD)

Data from the Macondo spill provide additional information about the species of coastal birds 

that may be affected in the event of a catastrophic spill of a similar nature and duration. This 

information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According 

to USFWS (2010d) and based on the latest reports, about 5,000 dead birds have been collected 

since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, over 

2,000 oiled birds have been collected alive and about 1,200 released (NMFS, 2010c). According 

to the International Bird Rescue Research Center (2010), bird species that have been treated for 

oiling include the following:

• Brown Pelican

• White Pelican

• Masked Booby

• Magnificent Frigatebird

• Laughing Gull

• Herring Gull

• Northern Gannet

• Black Crowned Night Heron

• Tri-colored Heron

• Green Heron

• Cattle Egret

• Snowy Egret

• Reddish Egret

• Least Bittern

• Common Tern

• Royal Tern

• Caspian Tern

• Sandwich Tern

• Forster’s Tern

• Black Tern

• Gull-billed Tern

• Least Tern
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• Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling

• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were 

Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, 

unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

Coastal birds can be exposed to oil as they float on the water 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 catasrophic spill reaching coastal waters. Issues for Brown Pelicans include direct 

contact with oil, disturbance by cleanup activities, and long-term habitat contamination.

C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater 

environment of the northern Gulf of Mexico. The biological oceanography of the region is 

dominated by the influence of the Loop Current, whose surface waters are among the most 

oligotrophic in the world’s oceans. Superimposed on this low-productivity condition are 

productive “hot spots” associated with entrainment of nutrient-rich Mississippi River water and 

mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an 

important role in determining biogeographic patterns and controlling primary productivity in the 

northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and 

larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae 

become part of the planktonic community for various lengths of time (10 to 100 days, 

depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, 

noise, and lights; effluent discharges; water intakes; and two types of accidents -a small fuel spill 

and a large oil spill (WCD).
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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.

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.

Impacts of Water Intakes

Seawater will be drawn from the ocean for once-through, non-contact cooling of machinery 

on the drilling rig. Rigs considered for use for activities described in this EP are not “new” 

facilities as defined by the NPDES permit and therefore are not subject to the cooling water 

intake regulations for Phase III facilities under Section 316(b) of the Clean Water Act.

The intake of seawater for cooling water will entrain plankton. The low intake velocity should 

allow most strong-swimming juvenile fishes and smaller adults to escape entrainment or 

impingement. However, drifting plankton would not be able to escape entrainment with the 

exception of a few fast-swimming larvae of certain taxonomic groups. Those organisms 

entrained may be stressed or killed, primarily through changes in water temperature during the 

route from cooling intake structure to discharge structure and mechanical damage (turbulence 

in pumps and condensers). Due to the limited scope and short duration of drilling activities, any 

short-term impacts of entrainment are not expected to be biologically significant to plankton or 

ichthyoplankton populations.

Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resources are discussed in recent EISs (MMS, 2007b, 2008).

For this EP, there are no unique site-specific issues with respect to spill impacts.
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The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will mitigate the potential for impacts on pelagic communities, including 

ichthyoplankton. EP Section H provides detail on spill response measures. Given the open 

ocean location of the lease area, the duration of a small spill and opportunity for impacts to 

occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton. Due 

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

be unlikely to produce detectable impacts on pelagic communities.

Impacts of a Large Oil Spill (WCD)

A large oil spill could affect water column biota including phytoplankton, zooplankton, 

ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more 

likely to affect these communities. While adult and juvenile fishes may actively avoid a large 

spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes are 

especially vulnerable to oiling because they inhabit the upper layers of the water column, and 

they will die if exposed to certain toxic fractions of spilled oil. Impacts potentially would be 

greater if local-scale currents retained planktonic larval assemblages (and the floating oil slick) 

within the same water mass.

C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for 

spawning, breeding, feeding, and growth to maturity. Under the Magnuson-Stevens Fishery 

Conservation and Management Act, as amended, Federal agencies are required to consult on 

activities that may adversely affect EFH designated in Fishery Management Plans developed by 

the regional Fishery Management Councils.

The BOEMRE (2011a,b) 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 
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features on the Texas-Louisiana OCS, the nearest of which is Ship Shoal South located in EW 947,

112 miles (181 km) north of the lease area along the shelf edge south of Louisiana.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only 

remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in 

this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly 

migratory species with EFH at or near the lease area include the following species and life stages

(NMFS, 2009):

• Atlantic bluefin tuna (spawn, eggs, 

larvae, adults)

• Bigeye thresher shark (all)

• Bigeye tuna (juveniles, adults)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Longfin mako shark (all)

• Oceanic whitetip shark (all)

• Sailfish (adults)

• Shortfin mako shark (all)

• Silky shark (all)

• Skipjack tuna (spawn, adults)

• Swordfish (larvae, juveniles, adults)

• Whale shark (all)

• 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 U.S. and Canadian coasts, followed by migration 

to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009). 

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin 

tuna currently do not warrant species protection under the ESA. NOAA said the species would 

be classified as a species of concern, however, effectively placing bluefin tuna 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 (EEZ). 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 BOEMRE’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some 

EFH requirements may change with the new agreement. Until the new agreement is in place, 

the 1999 Programmatic Consultation with the elements described above will be followed 

(BOEMRE, 2011a,b).

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, 
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Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico

(Figure 3). The nearest of these is Jakulla Bank, located approximately 65 miles (105 km)

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).

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as an FAD. In 

oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, 

dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface 

structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994; MMS, 2000, 2007b, 2008). 

This FAD effect would possibly enhance feeding of epipelagic predators by attracting and 

concentrating smaller fish species. Because the drilling rig is a single, temporary structure, any 

impacts on EFH for highly migratory pelagic fishes are considered minor.

Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling 

muds and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous 

discharges such as desalination unit brine and uncontaminated cooling water, 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.

Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, 

including fish eggs and larvae (ichthyoplankton). Due to the limited scope and short duration of 

drilling activities, any short-term impacts on EFH for highly migratory pelagic fishes are not 

expected to be biologically significant.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will help diminish the potential for impacts on EFH. EP Section H provides 

detail on spill response measures. Given the open ocean location of the lease area, the duration 

of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008). For this EP, 

there are no unique site-specific issues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.
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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 EFH being the 

topographic feature of Ship Shoal South located in EW 947, 112 miles (181 km) north of the 

lease area. A small fuel spill would float and dissipate on the sea surface and would not contact 

these features.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008). For this EP, 

there are no unique site-specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the 

water surface and potentially the subsurface as well. Given the extent of EFH designations in 

the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimp, 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.

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 topographic feature of Ship Shoal South, located in EW 947, 112 miles (181 km) north of the 

lease area, is designated as EFH under the corals and coral reefs management plan. 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

The BOEMRE (2011a,b) reexamined the analyses for archaeological resources presented in MMS 

(2007b, 2008), based on additional information available since the publication of these two 

documents and in consideration of the Macondo oil spill. Substantial new information that 

alters the impact conclusion for archaeological resources presented in MMS (2007b, 2008) has 

come to light as a result of BOEMRE-sponsored studies and industry surveys. Specifically, 

evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown 

to have occurred because of an incomplete knowledge of seafloor conditions in lease areas 

>200 m (656 ft) deep that have been exempted from high-resolution surveys. Since significant 

historic shipwrecks have recently been discovered outside the previously designated 
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high-probability areas (some of which show evidence of impacts from permitted activities prior 

to their discovery), beginning in 2011 a survey will be required for exploration and development 

projects. The GC 683/727 area is not on the list of leases with a high potential for historic 

shipwrecks. There were no indications of wrecks or other archaeological resources detected 

during the site clearance survey (GEMS, 2011). Anadarko will abide by the applicable 

requirements of NTL 2005-G07, which stipulate that work be stopped at the project site should 

any previously undetected archaeological resource be discovered after work has begun until 

appropriate surveys and evaluations have been completed.

Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely 

to affect shipwrecks. Impacts of a large oil spill (WCD) are the only IPFs considered. A small fuel 

spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.

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, in accordance 

with NTL 2005-G07 Anadarko will immediately halt operations, take steps to ensure that the site 

is not disturbed in any way, and contact the BOEMRE Regional Supervisor, Leasing and 

Environment, within 48 hours of its discovery. Anadarko would cease all operations within 

305 m (1,000 ft) of the site until the Regional Supervisor provides instructions on steps to take 

to assess the site’s potential historic significance and protect it.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered 

shipwreck site. As noted by MMS (2007b), should an oil spill contact a coastal historic site, such 

as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from 

oil contact and contamination of the site and its environment.

C.6.2 Prehistoric Archaeological Sites

Available evidence suggests that sea level in the northern Gulf of Mexico was at least 90 m 

(295 ft), and possibly as much as 130 m (427 ft), lower than present sea level during the period 

20,000 to 17,000 years Before Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern 

Gulf reached its present stand around 3,500 years B.P. (Pearson et al., 1986).
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During periods that the continental shelf was exposed above sea level, the area was open to 

habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is 

currently accepted to be around 12,000 years B.P. (Aten, 1983). The sea-level curve for the 

northern Gulf of Mexico proposed by Coastal Environments, Inc. (CEI) suggests that sea level at 

12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) below the 

present-day sea level (CEI, 1977, 1982). On this basis, the continental shelf shoreward of the 

45- to 60-m (148- to 197-ft) bathymetric contours has potential for prehistoric sites dating after 

12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry 

date of prehistoric man into North America, the MMS adopted the 60-m (197-ft) water depth as 

the seaward extent for archaeological site potential in Gulf of Mexico region.

With a water depth of 1,367 m (4,484 ft), the wellsite is well beyond the 60-m (197-ft) depth 

contour used by the BOEMRE as the seaward extent for prehistoric archaeological site potential 

in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, 

the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric 

archaeological resources because the oil would float and dissipate on the sea surface.

Impacts of a Large Oil Spill (WCD)

Because prehistoric archaeological sites are not found in the lease area, they would not be 

affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe 

subsurface blowout could resuspend and disperse sediments within a 300-m (984-ft) radius.

Along the northern Gulf Coast, prehistoric sites occur frequently along the barrier islands and 

mainland coast and along the margins of bays and bayous (MMS, 2007b). 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 relate to support vessel 

traffic. The support bases at Port Fourchon and Houma, Louisiana are not in wildlife 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 

120 miles (194 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.
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Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may 

have a minor incremental impact on coastal habitats. Over time with a large number of vessel 

trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support 

operations, including crew boats and supply boats as detailed in EP Section K, may have a minor 

incremental impact on coastal habitats or protected areas. Impacts will be minimized by 

following the speed and wake restrictions in harbors and channels.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b, 2008). 

Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and 

submerged seagrass beds. For this EP, there are no unique site-specific issues with respect to 

coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that during winter there is a 

17% probability of oil from a spill in the lease area reaching shorelines in Texas within 120 days, 

and a 14% probability in spring of oil reaching Louisiana shorelines within 120 days. 

The shorelines within the geographic range predicted by the OSRA modeling (Table 3) include 

extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered 

areas behind the barrier islands and in estuaries. National wildlife refuges and other protected 

areas along the coast are discussed in a recent lease sale EIS (MMS, 2007b) and Anadarko’s 

OSRP. Coastal and near coastal wildlife refuges, wilderness areas, and State and National parks

within the geographic range of the potential shoreline contacts after 120 days are presented in 

Table 6. 

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

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

County or Parish Wildlife Refuge, Wilderness Area, or

State/National Park

Cameron County, Texas

Lower Rio Grande Valley National Wildlife Refuge

Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park

Andy Bowie County Park 

Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas

Lower Rio Grande Valley National Wildlife Reserve

Laguna Atascosa National Wildlife Reserve 

Padre Island National Seashore

Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore

Laguna Madre Estuarine and Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore

Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas

Laguna Madre Estuarine and Coastal Marine Area

Mustang Island State Park

Lake Corpus Christi State Park

Port Aransas Park

Mission-Aransas National Estuarine Research Reserve

Aransas County, Texas 

Mission-Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Goose Island State Park
Table 6. (Continued).

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County or Parish Wildlife Refuge, Wilderness Area, or

State/National Park

Calhoun County, Texas

Mission-Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Matagorda Island State Park

Guadalupe Delta Wildlife Management Area

Welder Flats Coastal Preserve

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

Galveston Island State Park

Brazoria National Wildlife Refuge

Apffel Park

Seawolf Park

Old Fort Travis Park

Atkinson Island Wildlife Management Area

Ft. Anahuc Park

Anahuac National Wildlife Refuge

Mcfaddin National Wildlife Refuge

Jefferson County, Texas 

Mcfaddin National Wildlife Refuge

Sea Rim State Park

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

Plaquemines Parish, Louisiana 

Salvador Wildlife Management Area

Jean Lafitte National Historical Park and Preserve

Delta National Wildlife Refuge

Pass-a-Loutre Wildlife Management Area

Breton National Wildlife Refuge

St. Bernard State Park

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 

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. 
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Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on 

beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach 

at varying depths and may persist for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil 

contacting wetlands, approximately 2.7 ha (6.7 ac) of wetland vegetation will experience 

dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 

85% within 10 years. About 15% of the contacted wetlands are expected to be converted 

permanently to open-water habitat. The critical concentration of oil is that concentration above 

which impacts to wetlands will be long-term and recovery will take longer than two growing 

seasons, and which causes plant mortality and some permanent wetland loss. Critical 

concentrations of various oils are expected to vary broadly for wetland types and wetland plant 

species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in 

the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of 

oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, 

which have been reported to require from years to decades following a spill (MMS, 2007b).

C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEMRE has reexamined the analysis for recreational and commercial fishing presented in 

MMS (2007b, 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, 2011a,b).

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 

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 are caught by trawlers in water depths 

of about 250 to 550 m (820 to 1,804 ft). Tilefish are caught by bottom longlining in water 

depths from about 165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).
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Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) 

(Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to 

recreational fishers would be petroleum rigs offshore Texas and Louisiana. Due to the distance 

from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and 

lights). Two potential accidents are also addressed below – a small fuel spill and a large oil spill 

(WCD).

Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For 

example, in January 1999, a portion of a pelagic longline snagged on the acoustic Doppler 

current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 

2002). The line was removed without incident. Generally, longline fishers use radar and are 

aware of offshore structures and ships when placing their sets. Therefore, little or no impact on 

pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no 

adverse impacts are anticipated. Other factors such as effluent discharges are likely to have 

negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small 

area of ocean affected, and the intermittent nature of the discharges.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H

provides detail on spill response measures. Given the open ocean location of the lease area, the 

duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small 

fuel spill. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions. Fishing activities could be 

interrupted due to the activities of response vessels operating in the lease area. A small fuel 

spill would not affect coastal water quality because the spill would not be expected to make 

landfall or reach coastal waters prior to breaking up (see Section A.9.2).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on fishing activities are discussed in recent EISs (MMS, 2007b, 2008). For 

this EP, there are no unique site-specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of 

Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in 

fishery closures, depending on the duration of the spill, the oceanographic and meteorological 

conditions at the time, and the effectiveness of spill response measures. The recent Macondo 

spill provides information about the maximum potential extent of fishery closures in the event 

of a large oil spill in the Gulf of Mexico (NMFS, 2010d). At its peak on 12 July 2010, closures 

encompassed 217,821 km2 (84,101 mi2

), or 34.8% of the U.S. Gulf of Mexico EEZ.
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C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health 

and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will potentially alleviate the potential for impacts. EP Section H provides detail 

on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect 

only a small area of the open ocean 120 miles (194 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).

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 (Centers for Disease Control and Prevention, 

2010a). Wildlife cleaning and rehabilitation workers have reported concerns including scrapes 

and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. 

Hand, shoulder, or back pain was also reported by some wildlife-cleaning workers. Personnel 

working on offshore vessels or providing direct oversight to offshore vessels, including 

USCG personnel, civilian contractors, and other responders who were exposed to oil and 

dispersants, had a 7 to 12 times higher prevalence of upper respiratory symptoms and cough 

than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential 

occupational hazard for spill response workers in general was heat stress from work in a hot and 

humid environment. Initial symptoms from cleanup workers who sought medical care in 

Louisiana were typical of acute exposure to hydrocarbons or H2S such as headaches, dizziness, 

nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010).

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 
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expected to move permanently into the area. The project will have a negligible impact on 

socioeconomic conditions such as local employment, existing offshore and coastal infrastructure 

(including major sources of supplies, services, energy, and water), and minority and lower 

income groups. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H

provides detail on spill response measures. Given the open ocean location of the lease area, the 

duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as 

the spill response would use existing facilities, resources, and personnel.

Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008). 

For this EP, there are no unique site-specific issues with respect to employment and coastal 

infrastructure. A large spill could cause economic impacts in several ways: it could result in 

extensive fishery closures that put fishermen out of work; it could result in temporary 

employment as part of the response effort; it could result in adverse publicity that affects 

employment in coastal recreation and tourism industries; and it could result in another 

suspension of OCS drilling activities, including service and support operations that are an 

important part of local economies.

In addition to the analyses presented by MMS (2007b, 2008) and BOEMRE (2011a,b), a recent 

study explored the economic impacts of the Macondo spill on oil and gas industry employment 

due to suspension of deepwater drilling (Inter-Agency Economic Report, 2010). The study 

indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico 

fell by about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs 

along the Gulf Coast. Total spending by drilling operators is estimated to have declined by 

$1.8 billion over a 6-month period; this direct reduction in spending affected employment in the 

industries that supply the Gulf drilling industry and in all other industries affected by declines in 

consumer and business spending (Inter-Agency Economic Report, 2010).

C.8.4 Recreation and Tourism

BOEMRE has reexamined the 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, 2011a,b).

There are no known recreational uses of the lease area. Recreational resources and tourism in 

coastal areas would not be affected by any routine activities due to the distance from shore. 

Compliance with NTL 2007-G03 will minimize the chance of trash or debris being lost overboard 

from the drilling rig and subsequently washing up on beaches.
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Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will potentially help mitigate and reduce the potential for impacts. 

EP Section H provides detail on spill response measures. Given the open ocean location of the 

lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are 

no known recreational or tourism activities occurring in the lease area, and as explained in 

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

prior to breaking up.

Impacts of a Large Oil Spill (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in recent EISs 

(MMS, 2007b, 2008). For this EP, there are no unique site-specific issues with respect to these 

impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate 

including the effectiveness of response measures. A large spill that reached coastal waters and 

shorelines could adversely affect recreation and tourism by contaminating beaches and 

wetlands, resulting in negative publicity that encourages people to stay away. Based on the 

revised OSRA modeling (BOEMRE, 2011a) as summarized in Section A.9.3 (Table 3), there is a 

14% probability in winter of oil from a spill in the lease area reaching shorelines in Texas and a 

14% chance in spring of contacting shorelines in Louisiana within 120 days.

In addition to the analysis presented by MMS (2007b, 2008), recent and ongoing studies have 

explored the economic impacts of the Macondo spill including tourism and “brand” damage 

(IEM, 2010; Oxford Economics, 2010). The U.S. Travel Association has estimated the economic 

impact of the Macondo spill on tourism across the Gulf Coast over a 3-year period at 

$22.7 billion (Oxford Economics, 2010). 

C.8.5 Land Use

Land use along the northern Gulf Coast is discussed in recent lease sale EISs (MMS, 2007b, 

2008). There are no routine IPFs potentially affecting land use. The project will use existing 

onshore support facilities in Louisiana. The land use at the existing shorebase sites is industrial. 

The project will not involve any new construction or changes to existing land use and, therefore, 

will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and 

services including scarce coastal resources, will represent a small fraction of the level of activity 

occurring at the shorebases.

A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on 

land use, as the response would be staged out of existing shorebases and facilities.

Impacts of a Large Oil Spill (WCD)

The initial response for a large oil spill would be staged out of existing facilities, with no effect on 

land use. A large spill could have limited temporary impacts on land use along the coast if 

additional staging areas were needed. For example, during the Macondo spill, temporary 
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staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response 

and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging 

areas could be needed. These areas would eventually return to their original use as the 

response is demobilized.

C.8.6 Other Marine Uses

The lease area is not located within any USCG-designated fairway or shipping lane or Military 

Warning Area. Anadarko will comply with BOEMRE requirements and lease stipulations to avoid 

impacts on uses of the area by military vessels and aircraft.

The nearest wellheads to the proposed operations are GC 683 #1 and GC 727 #001. GC 683 #1 is 

a side-tracked and completed well 56 m (185 ft) southeast of GC 727 #002 well. GC 727 #001 is 

a temporarily abandoned well 2.3 miles (3.7 km) southwest of GC 727 #002 (GEMS, 2011). No 

other existing man-made features or potentially hazardous seafloor conditions are identified in 

the vicinity of the proposed wellsite. 

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.

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. Anadarko will comply with BOEMRE requirements and lease 

stipulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be 

required to ensure that no anchoring or seafloor-disturbing activities occur near the existing 

pipelines and flowlines.

D. Environmental Hazards

D.1 Geologic Hazards

The geohazard and site clearance assessments conducted by GEMS (2003; 2011) concluded that 

the wellsite is free of any significant geological hazards and suitable for the proposed activities. 

See EP Section C for supporting geological and geophysical information.

D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed 

activities. Extreme weather, including high winds, strong currents, and large waves, was 

considered in the design criteria for the drilling rigs under consideration for this project. High 

winds and limited visibility during a severe storm could disrupt support activities (vessel and 
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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 the location of the wellsite and the selection of a drilling unit, 

were considered by Anadarko in developing the proposed action.

F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and 

BOEMRE lease stipulations and NTLs. The project will comply with all applicable Federal, State, 

and local requirements concerning air pollutant emissions, discharges to water, and solid waste 

disposal. All project activities will be conducted under guidance by Anadarko’s OSRP and will 

include the measures described in EP Section H.

G. Consultation

No persons or agencies were consulted during the preparation of this EIA.

H. Preparers

The EIA was prepared by CSA International, Inc. Contributors included

• M. John Thompson (Senior Scientist);

• Carlyle Kalloo (Senior Scientist);

• Neal Phillips, Ph.D. (Senior Scientist);
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• Luis Lagera, Jr., Ph.D. (Senior Scientist);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director); and

• Kim Dunleavy (Technical Editor).

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O 

ADMINISTRATIVE INFORMATION 

(a) Proprietary Information 

Proprietary copies of this plan contain information not available to the public and include 

structure maps, seismic information, cross sections, depths of wells, etc. 

(b) Bibliography 

Shallow Hazards Report 

Final Sale Package for Central Gulf of Mexico Sale Numbers 166 and 157.