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-07604

Type - Supplemental Exploration Plan

Lease(s) - OCS-G21817 Block - 768 Green Canyon Area

Operator - Anadarko Petroleum Corporation

Wells B and BB

Not Found

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.

Michelle Griffitt

Plan Coordinator

Description -

Rig Type -

Subject:

From:

April 29, 2013
SUPPLEMENTAL EXPLORATION PLAN 

S-7604 

ANADARKO PETROLEUM CORPORATION 

GREEN CANYON BLOCK 768 

OCS-G 21817 

PUBLIC COPY 

RECORD OF CHANGE LOG 

Submission 

Type 

Date Sent to 

BOEMRE 

Summary of 

Submission 

Page 

Numbers 

Initial 2/20/2013 Initial plan submittal All 

Amendment 3/19/2013 Clarify drilling fluid info 63-64 

Amendment 4/04/2013 Update NTL reference 82 

Final 4/04/2013 Submit final EP All 

Amendment 4/15/2013 Revised support vessel 

info 

84 

 
 

PUBLIC 

SUPPLEMENTAL EXPLORATION PLAN 

GREEN CANYON BLOCK 768 

OCS-G 21817 

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 

1 – CDs Public Information

February, 2013 
 

SUPPLEMENTAL EXPLORATION PLAN 

LEASE OCS-G 21817 

GREEN CANYON BLOCK 768 

 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 two wells total in Green Canyon Block 768. 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 locations 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 768 wells 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) Additional Pollution Prevention Measures 

No additional measures are proposed under this plan. The activities proposed in this plan are not 

located offshore Florida. 
 

(g) Description of Previously Approved Lease Activities 

Anadarko has previously approved well locations in Green Canyon Block 768. Approval was 

granted to drill and complete the following two well locations under the Initial Exploration Plan 

(filed by Samedan Oil Corporation) for Green Canyon Block 768 (Plan Control No. N-7895) 

approved on October 24, 2003: 

Well 

Location 

Status of Well Location Potential Future Operations 

A Used location to drill GC 768 #SS001 

well. 

Currently producing well. 

B Used location to drill GC 768 #SS002 

well.

Currently producing well. 

Approval was granted to drill and complete the following well location under the Supplemental 

DOCD for Green Canyon Block 768 (Plan Control No. S-6985) approved on April 27, 2007: 

Well 

Location 

Status of Well Location Potential Future Operations 

003 Used location to drill GC 768 #SS003 

well. 

Currently producing well.
U.S. Department of the Interior OMB Control Number: 1010-0151

Bureau of Ocean Energy Management OMB Approval Expires: 12/31/14

 

OCS PLAN INFORMATION FORM 

General Information 

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

Company Name: BOEM Operator Number: 

Address: Contact Person: 

Phone Number: 

E-Mail Address: 

If a service fee is required under 30 CFR 550.125(a), provide the Amount paid Receipt No. 

Project and Worst Case Discharge (WCD) Information

Lease(s): Area: Block(s): Project Name (If Applicable): 

Objective(s) Oil Gas Sulphur Salt Onshore Support Base(s): 

Platform/Well Name: Total Volume of WCD: API Gravity: 

Distance to Closest Land (Miles): Volume from uncontrolled blowout: 

Have you previously provided information to verify the calculations and assumptions for your WCD? Yes No 

If so, provide the Control Number of the EP or DOCD with which this information was provided 

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

Do you propose to use a vessel with anchors to install or modify a structure? Yes No 

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

Description of Proposed Activities and Tentative Schedule (Mark all that apply) 

Proposed Activity Start Date End Date No. of Days 

Drill and Complete Well Location B 

Drill and Complete Well Location BB

Description of Drilling Rig Description of Structure 

Jackup Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Fixed platform Compliant tower 

Semisubmersible Submersible Spar Guyed tower

DP Semisubmersible Other (Attach Description) 

Drilling Rig Name (If Known): 

Floating production 

system 

Other (Attach Description) 

Description of Lease Term Pipelines 

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

Form BOEM- 0137 (December 2011- Supersedes all previous editions of this form which may not be used.) Page 1 of 4
OCS PLAN INFORMATION FORM (CONTINUED) 

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): 

Previously reviewed under an approved EP or 

DOCD? 

Yes No 

Is this an existing well 

or structure? 

Yes No If this is an existing well or structure, list the 

Complex ID or API No. 

Do you plan to use a subsea BOP or a surface BOP on a floating facility to conduct your proposed activities? Yes No 

WCD info For wells, volume of uncontrolled 

blowout (Bbls/day): 

For structures, volume of all storage and 

pipelines (Bbls): 

API Gravity of 

fluid 

Surface Location Bottom-Hole Location (For Wells) Completion (For multiple completions, 

enter separate lines) 

Lease No. OCS OCS OCS 

OCS 

Area Name 

Block No. 

Blockline 

Departures 

(in feet)

N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L 

N/S Departure: F____ L 

N/S Departure: F____ L 

E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L 

E/W Departure: F____ L 

E/W Departure: F____ L 

Lambert XY 

coordinates 

X: X: X: 

X: 

X: 

Y: Y: Y: 

Y: 

Y: 

Latitude/ 

Longitude

Latitude Latitude Latitude 

Latitude 

Latitude 

Longitude Longitude Longitude 

Longitude 

Longitude 

Water Depth (Feet): MD (Feet): TVD (Feet): 

Anchor Radius (if applicable) in feet: 

MD (Feet): 

MD (Feet): 

MD (Feet): 

TVD (Feet): 

TVD (Feet): 

TVD (Feet): 

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 = 

 

Form BOEM- 0137 (December 2011- Supersedes all previous editions of this form which may not be used.) Page 2 of 4
OCS PLAN INFORMATION FORM (CONTINUED)

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): 

Previously reviewed under an approved EP or 

DOCD? 

Yes No 

Is this an existing well 

or structure? 

Yes No If this is an existing well or structure, list the 

Complex ID or API No. 

Do you plan to use a subsea BOP or a surface BOP on a floating facility to conduct your proposed activities? Yes No 

WCD info For wells, volume of uncontrolled 

blowout (Bbls/day): 298,799 BOPD

For structures, volume of all storage and 

pipelines (Bbls): n/a

API Gravity of 

fluid

Surface Location Bottom-Hole Location (For Wells) Completion (For multiple completions, 

enter separate lines) 

Lease No. OCS OCS OCS

OCS

Area Name 

Block No. 

Blockline

Departures 

(in feet)

N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L

N/S Departure: F____ L 

N/S Departure: F____ L 

E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L 

E/W Departure: F____ L 

E/W Departure: F____ L 

Lambert XY

coordinates 

X: X: X: 

X:

X:

Y: Y: Y:

Y:

Y:

Latitude/

Longitude

Latitude Latitude Latitude 

Latitude

Latitude

Longitude Longitude Longitude 

Longitude

Longitude

Water Depth (Feet): MD (Feet): TVD (Feet): 

Anchor Radius (if applicable) in feet: 

MD (Feet): 

MD (Feet): 

MD (Feet): 

TVD (Feet): 

TVD (Feet): 

TVD (Feet): 

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 = 

Form BOEM- 0137 (December 2011- Supersedes all previous editions of this form which may not be used.) Page 2 of 4

GC 768 "BB" x

x n/a

x

G 218

Green Canyon

768

358'FNL

3408'FWL

2,300,208.37

9,883,801.63

27.2229219

90.9693098

5257'

N/A

 

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 BSEE 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 

10,000 bbls per well** 

Synthetic-based (internal olefin, ester) 10,000 bbls per well 

Oil-based NA 

**The actual volume ordered out will be an estimated 10,000 bbls/well of mud. Once on location this volume will 

be cut back and mixed with seawater to different desired mud weights which will increase the volume that is 

discharged at the seafloor. The estimated volume that will be discharged at the seafloor will be approximately 

32,000 bbls/well. 

(c) New or Unusual Technology 

Anadarko does not propose to use any new or unusual technology to drill the well 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 

Green Canyon 768 #4 well (EP Location “B”) is addressed in this blowout scenario since it is the location 

with the highest potential worst case discharge (WCD) rate for Green Canyon Block 768. A similar 

approach would be taken in the event of a blowout for the GC 768 “BB” well covered under this plan. 
 

Based on NTL No. 2010-N06 guidance, the maximum hydrocarbon discharge for Green Canyon Block 

768 is calculated to be 298,799 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. 

Information Requirements 

Blowout Scenario 

The GC 768 #4 well will be drilled to the sand objectives, as outlined in the Geological and Geophysical 

Information section of this Plan, utilizing a MODU rig with a marine riser and subsea BOP. 

The Blowout Scenario assumes the well has reached its objective TD and a hydrocarbon influx occurs 

from the objective intervals, followed by a well control event. The subsea BOP and marine riser fail, and 

a blowout occurs at the seabed. The WCD scenario assumes 12-1/4” open-hole across the objective 

intervals and 14” casing back to the mudline, as per the attached wellbore schematic (Attachment H-1). 

The WCD scenario assumes simultaneous flow from the objective zones. 

Estimated Flow Rate of the Potential Blowout 

Category Supplemental EP 

Type of Activity Drilling 

Facility Location (area/block) Green Canyon Block 768 

Facility Designation MODU 

Distance to Nearest Shoreline (miles) 127 

Uncontrolled Blowout (volume per day) 298,799 bbls 

Type of Fluid(s) Crude Oil 

a) Potential for the well to bridge over: 

Mechanical collapse of the reservoirs in the open-hole section of the wellbore was not considered. 

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 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 ROB 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 January 30, 2013, there were over 20 

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 drillship 

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

to Chevron and is on location in Walker Ridge 677 working on the St. Malo North Prospect. 

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 5,500’ of water with at least a 10k Stack is required for any relief well 

operation. The Transocean Discoverer Clear Leader drillship meets these 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 85 days, for a total estimated time of 92–106 days from time of blowout to finishing the 
 

relief well. 

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, 2, and 3, 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 298,799 BOPD based on the objective sand 

intervals. 

 The maximum total volume during a blowout could potentially be 31,672,694 bbls assuming 

106 days for the maximum duration of a blowout, multiplied by the worst case daily 

uncontrolled blowout volume of 298,799 bbls. 

g) Measures taken to reduce the likelihood of a blow-out: 

 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 it provides assurance 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, which is 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 perform pressure tests, in accordance with the law, to confirm 

integrity on all relevant barriers. 

In addition, all intermediate and production casing strings returned to the wellhead will be 

locked down prior to proceeding with subsequent wellbore construction. 

 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, an independent third-party will verify the subsea BOP is 

designed for the specific equipment on the rig and the 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. It will also provide periodic assurance 

on the performance of both primary and secondary BOP control systems including actual 

interface operations with the ROV and ROV panel. 

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

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

training certificate, renewed 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 manage a well control situation; thereby minimizing 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. Wild Well Control, Inc. will be contacted and 

mobilized, if required, to support Anadarko’s operational team, both at onshore and offshore 

locations. 

 The conceptual relief well design is similar to the design of the GC 768 #4 well with respect 

to identical casing weights, grades, and setting points. A site clearance letter has been 

prepared that includes an assessment of the specific seafloor and subsurface hazards for an 

area within a 2,000 ft radius of the primary location, within which a relief well could be 

drilled. There is negligible potential for high-density chemosynthetic or other benthic 

communities within this 2,000 ft radius. 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 will be submitted and reviewed to determine the 

most appropriate location of the relief well. 

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

from surface to TD. Back-up long-lead equivalent to the original well design will be carried 

in stock to allow a rapid response. This includes a spare deepwater subsea wellhead system, 

the large OD casing (36”, 28”, 22”, 18”, 16”), and required connectors. 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 are 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 of the EP, along with the attachments. 

(b) Structure Contour Maps 

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

block, the surface locations of each well and locations 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 each proposed well are 

enclosed as Attachment C-3.

(e) Shallow Hazards Report 

A Shallow Hazards Report prepared by Fugro GeoServices, Inc. for Green Canyon Block 768 was 

previously submitted with the Initial Exploration Plan for the block. 

(f) Shallow Hazards Assessment 

Shallow Hazards Site Clearance Letters for the proposed well locations in Green Canyon Block 768 are 

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 wells 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. 








































 

D 

HYDROGEN SULFIDE INFORMATION 

The proposed GC 768 “B” well will only penetrate sections which were previously penetrated by 

three of the GC 768 wells within approximately 250’ of the surface location of the proposed 

wells and had no recorded amounts of Hydrogen Sulfide. The objective intervals have been 

penetrated by all of the Ticonderoga Field wells mentioned above, the closest being the Kerr 

McGee (Anadarko) GC 768-2 (API # 608114044700) well at a distance of 16,000’. None of 

these penetrations encountered any Hydrogen Sulfide. 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 5,257 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, and surface location of the proposed well is included in Section A. 

Analysis 

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

within 2000 feet of each proposed muds and cuttings discharge location. 

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

within 250 feet of any seafloor disturbances. 

(b) Topographic Features Map 

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

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

(c) Topographic Features Statement (Shunting) 

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

Protective Zone of an identified topographic feature. Therefore, the topographic features 

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

(d) Live Bottoms (Pinnacle Trend) Map 

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

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

G04. 

(e) Live Bottoms (Low Relief) Map 

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

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

(f) Potentially Sensitive Biological Features 

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

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

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

Green Canyon Block 768 is 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

Lease Area Coastal Gulf of Mexico

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, E

b 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.

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 Block 768 is not located in an area designated as having high archaeological potential and, as such, 

an Archaeological Report is not required per NTL No. 2011-JOINT-G01. However, an Archaeological Report 

prepared by Fugro Geoservices, Inc covering the proposed Green Canyon Block 768 well locations is being 

submitted 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. Projected amounts may vary during the course 

of drilling operations. 

(a) Projected Generated Wastes 

Type of Waste Composition Projected Amount Treatment/Storage/Disposal 

Synthetic-based 

drilling fluids 

Synthetic-based 

drilling muds 

10,000 bbls/well Re-use and/or transport to shore in 

DOT approved containers 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 

2,500 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) 

32,000 bbls/well** Discharge overboard or at seafloor 

Cuttings wetted 

with water-based 

fluids 

Cuttings coated with 

water-based drilling 

muds/fluids 

2,000 bbls/well Discharge overboard 

Chemical product 

waste (well 

treatment fluids) 

Ethylene glycol 

Methanol 

500 bbls total 

125 bbls total 

Transport to shore in DOT 

approved containers to Fourchon, 

Louisiana for pick up. 

Completion Fluids Brine, spent acid, 

prop sand, debris 

3,000 bbls/well Transport to shore in DOT 

approved containers to Fourchon, 

Louisiana and on to Newpark 

Base. 

Non-pollutant 

completion fluids 

Low density 

uninhibited 

completion brines 

5,000 bbls/well Discharge overboard 

Workover fluids Brine, spent acid, 

prop sand, debris 

3,000 bbls/well Transport to shore in DOT 

approved containers to Fourchon, 

Louisiana and on to Newpark 

Base. 

Trash and debris Refuse generated 

during operations 

250 bbls total Transport to shore in disposal bags 

by vessel to shorebase for pickup 

by municipal operations. 

*Sanitary Wastes Treated human body 

waste 

750,000 gals total Chlorinate and discharge 

overboard 

*Domestic Waste Gray water 750,000 gals total Chlorinate and discharge 

overboard 

Deck drainage Platform washings 

and rainwater 

525,000 total Treat for oil and grease and 

discharge overboard 

Produced water N/A N/A N/A 

Desalinization Unit Seawater 52,500 bbls total Discharge overboard 
 

Wash water Drill water (fresh) 7,500 bbls total Discharge overboard 

Blowout preventer 

fluid 

Blend (3% Stack 

Magic & Filtered 

Fresh Water) 

19,821 gals total Discharge at seafloor 

Ballast water Seawater 47,650 m3/year Discharge overboard 

Bilge water Seawater 47,550 bbls total Discharge overboard through 15 

ppm equipment 

Excess cement at 

the seafloor 

Nitrified cement 

slurry 

700 bbls/well Discharge at seafloor 

Fire water Seawater 137,142 bbls/day/well Discharge overboard 

Cooling water Seawater 137,142 bbls/day/well Discharge overboard 

Produced Sand N/A N/A N/A 

Used oil Excess oil from 

engines 

538 bbls total Transport in DOT approved 

containers to shore for recycling 

*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. 

**The actual volume ordered out will be an estimated 10,000 bbls/well of mud. Once on location this volume will 

be cut back and mixed with seawater to different desired mud weights which will increase the volume that is 

discharged at the seafloor. The estimated volume that will be discharged at the seafloor will be approximately 

32,000 bbls/well (NOTE: there will be two wells for a total of 64,000 bbls). 

(b) Projected Ocean Discharges

Type of Waste Total Amount to be 

Discharged 

Discharge Rate Discharge Method 

*Sanitary Wastes 750,000 gals 25 gals per person 

daily 

Chlorinate and discharge 

overboard 

*Domestic waste 750,000 gals 25 gals per person 

daily 

Chlorinate and discharge 

overboard 

Deck drainage 525,000/bbls 3500 bbls/day Treat for oil and grease and 

discharge 

Blowout preventer fluid 19,821 gals total 925 gals/week/well; 

Vents on a weekly 

basis 

Discharge at seafloor 

Desalinization Unit 52,500 bbls 350 bbls/day Discharge overboard 

Wash water 7,500 bbls 50 bbls/day Discharge overboard 

Ballast water 47,650 m3/year Not continuous Discharge overboard 

Bilge water 47,550 bbls 317 bbls/day Discharge overboard through 15 

ppm equipment 

Excess cement at the 

seafloor 

1,400 bbls 20 bbls/min Discharge at seafloor 

Fire water 20,571,300 bbls 137,142 bbls/day Discharge overboard 

Cooling water 20,571,300 bbls 137,142 bbls/day Discharge overboard 

Cuttings wetted with 

Water-based fluids 

4,000 bbls 1,000 bbls/hr max Discharge overboard 

Water-based drilling 

fluids 

64,000 bbls** 1,000 bbls/hr max Discharge at seafloor or 

overboard 

Cuttings wetted with 

Synthetic-based fluids 

5,000 bbls 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 

10,000 bbls 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. 

**The actual volume ordered out will be an estimated 10,000 bbls/well of mud. Once on location this volume will 

be cut back and mixed with seawater to different desired mud weights which will increase the volume that is 

discharged at the seafloor. The estimated volume that will be discharged at the seafloor will be approximately 

32,000 bbls/well (NOTE: there will be two wells for a total of 64,000 bbls). 

 (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.

(c) Summary Information 

The following tables summarize information regarding the peak year emissions generated from the Plan 

Emissions and Complex Total Emissions: 

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) 79.03 4229.10 79.03 

Sulphur dioxide (SO2) 362.57 4229.10 362.57 

Nitrogen oxides (NOx) 2717.79 4229.10 2717.79 

Volatile organic compounds (VOC) 82.41 4229.10 82.41 

Carbon monoxide (CO) 598.57 85904.27 598.57 

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) 78.27 4229.10 78.27 

Sulphur dioxide (SO2) 359.07 4229.10 359.07 

Nitrogen oxides (NOx) 2691.62 4229.10 2691.62 

Volatile organic compounds (VOC) 81.62 4229.10 81.62 

Carbon monoxide (CO) 592.86 85904.27 592.86 
 

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 August 24, 2012 for Anadarko Petroleum Corporation and 

its subsidiaries, Anadarko US Offshore Corporation and Anadarko E&P Company L.P. 

(Company Numbers 00981, 02219 and 00148, respectively) in accordance with 30 CFR Part 

254. 

(ii) Spill Response Sites 

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

Houma, Louisiana 

Harvey, Louisiana 

Venice, Louisiana 

Lake Charles, Louisiana 

Galveston, Texas 

Fourchon, Louisiana 

Harvey, Louisiana 

Venice, Louisiana 

Cameron, Louisiana 

Galveston, Texas 

(iii) OSRO Information 

Anadarko maintains a contract with Clean Gulf Associates (CGA) for spill response equipment. 

Various equipment locations are staged throughout the Gulf of Mexico. CGA equipment can be 

referenced on their website: http://www.cleangulfassoc.com/. 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 the Marine Spill Response Corporation (MSRC) for 

spill response equipment. MSRC stages equipment throughout the Gulf of Mexico and has 

recently completed a large expansion of its resources, with particular focus on deepwater. The expansion 

is known as “Deep Blue”. MSRC capabilities and a complete equipment listing are available online at: http://www.msrc.org/. 

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 

(area/block) GB 346 GC 768 

Facility Designation * GB 346 “A” GC 768 “B” 

Distance to Nearest 

Shoreline 118 miles 127 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** 298,799 bopd 

Type of Oil(s) Oil Oil 

API Gravity 30.1o 32.2 o /30.9o

* 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 approved under EP Plan Control No. N-9579. Anadarko elected to denote a higher volume in the 

Regional OSRP for planning purposes to demonstrate equipment response capabilities per previous discussions with Rusty 

Wright. 

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

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 scenarios determined for our EP does not replace the 

worst-case scenario in our Regional OSRP approved on August 24, 2012, 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 768: 

Discussions regarding geologic information are considered proprietary and have been omitted 

from this public copy of the EP, along with the attachments. 

 (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 298,799 

BOPD with an API gravity of 32.2o

. 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 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 Block 768 is located within Launch Area 45. According to the BOEMRE 

OSRAM, the trajectory indicates a 4% probability of potential impact to the shoreline in 

Cameron Parish, Louisiana. The results are shown in Table H-2. 

Cameron Parish is 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. 

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 298,799 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 14% (41,832 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% (14,940 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 

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 256,967 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 

dynamically positioned (DP) semi-submersible drilling rig would be determined by 

marine surveyors. Operations and Unified Command would continue to assess the 

adequacy of response equipment capacities based on this continually updated mass 

balance. 

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

objectives and priorities. 

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

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

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

request approval to utilize dispersants. 
 

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

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

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

application. 

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

surveillance aircraft and spotter. Mobilize MSRC contracted aircraft(s) if needed. 

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/MSRC 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 

Louisiana CZM Containment Response Information 

Anadarko has the capability to respond and contain, to the maximum extent practicable as 

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

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

equipment is subject to availability and location, weather conditions, potential security zones 

around the spill site, and site/well specific assessment data. Personnel safety is always first and 

foremost. Refer to further details on equipment and timing provided in Section H–Oil Spill 

Information and Table H-3 of the EP. 

The potential WCD will be further evaluated during the Application for Permit to Drill (APD) 

process, including the Well Containment Screening Tool (WCST) and associated subsea 

containment plan for enhanced planning purposes. 

There will be no new or unusual technology deployed that has not been previously deployed for 

Gulf of Mexico oil spill prevention, control, and/or cleanup. 
 

Table H-1 

Worst Case Discharge Calculation 

(Based on Blowout during Drilling Operations)

Calculations for Uncontrolled Blowout> 10 miles from shore: Block 768 

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

 ii. API Gravity 32.2 ̊

 iii. EP Location Used for NTL No. 2010-N06 WCD for GC 768 SEP well “B” 

 iv. Largest Anticipated WCD Rate during blowout 298,799 BOPD 

 v. WCD Total for Drilling Operations for GC 768 (> 10 miles from shore): 298,799 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 768 

Drilling 

(127 miles from 

shore) 

G21817 LA 45 

Central 

Planning 

Area 

Calhoun, TX 

Matagorda County, TX 

Brazoria County, TX 

Galveston County, TX 

Jefferson County, TX 

Cameron Parish, LA 

Vermilion Parish, LA 

Iberia, LA 

Lafourche Parish, LA 

Terrebonne Parish, LA 

Plaquemines Parish, LA 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

-- 

1 

1 

1 

2 

1 

4 

2 

1 

1 

2 

2 
Table H-3 

WCD Scenario Drilling Activities – Based on a single well uncontrolled blowout (127 miles from shore) Green Canyon Block 768 298,799 BOPD (initial volume) 256,967 BOPD (after evaporation/dispersion) API Gravity 32.2o 

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 

Deep Blue Responder LFF 100 Brush + OSRV 6,600' 44" Sea Sentry Boom 660' 67" LAMOR 

18,086 4,000 1 

1 

14 crew MSRC/Fourchon Fourchon 

0 2 2 

1 4 32 

Gulf Coast Responder Transrec 350 + OSRV 5,280' 44" Sea Sentry Boom 2,640' 67" LAMOR 

10,567 4,000 1 

1 

14 crew MSRC/Lake Charles Lake Charles 

0 2 2 

1 4 37 

Louisiana Responder Transrec 350 + OSRV 2,640' 44" Sea Sentry II Boom 5,280' 67" LAMOR 

10,567 4,000 1 

1 

14 crew MSRC/Fort Jackson Fort Jackson 

0 2 2 

1 4 34 

FRU Operators Utility Boat 

4,251 200 1 

6 1 

CGA/Ingleside STARS VOO 

Ingleside 

0 2 2 1 2 2

FRU Operators Utility Boat 

4,251 200 1 

6 1 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 2 19 

FRU Operators Utility Boat 

4,251 200 1 

6 1 

CGA/Lake Charles STARS VOO 

Cameron 

.5 

2 2 1 2 15

FRU Operators Utility Boat 

4,251 200 1 

6 1 

CGA/Morgan City STARS VOO 

Morgan City 

.5 

2 2 1 2 14

FRU Operators Utility Boat 

4,251 100 1 

6 1 

CGA/Harvey STARS VOO 

Harvey 

.5 

2 2 1 2 13 

FRU Operators Utility Boat 

8,502 400 2 

12 

2 

CGA/Leeville STARS VOO 

Leeville 

.5 

2 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 

FRU Operators Utility Boat 

8,502 400 2 

12 

2 

CGA/Venice STARS VOO 

Venice 

0 2 2 1 2 15 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

89,150 10,000 5 sets 

30 

5 

CGA/Galveston STARS VOO 

Galveston 

0 2 2 1 12 18 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

53,490 6,000 3 sets 

18 

3 

CGA/Leeville STARS VOO 

Leeville 

0 2 2 1 12 14 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

17,830 2,000 1 set 

6 1 

CGA/Fourchon STARS VOO 

Fourchon 

0 2 2 1 12 13 

Koseq Skimming Arms Operators Vessel w/ storage/hull 

35,660 4,000 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 

6,679' 44" Sea Sentry II Boom VOO 

-- -- 20 

10 crew 

MSRC/Lake Charles STARS Lake Charles 

0 2 

1 2 22 

1,980' 44" Sea Sentry II Boom VOO 

-- -- 12 

6 crew 

MSRC/Fort Jackson STARS Fort Jackson 

0 2 

1 2 22..
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 

3,190' 44" Sea Sentry II Boom VOO 

-- -- 20 

10 crew 

MSRC/Pascagoula STARS Pascagoula 

0 2 

1 2 19 

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 316,609 321,270 

Spill Team Area Responders (STARS) called out by Marine Spill Response Corporation (MSRC) Vessel of Opportunity=VOO EMS=Enterprise Marine Services K-Sea=K-Sea Operating Partnership 
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 

Foilex 250 Skimmer Storage Bladder 

3,977 500 1 

3 MSRC/Lake Charles Cameron 0 2 1 2 15 

Foilex 250 Skimmer Storage Bladder 

3,977 500 1 

3 MSRC/Fort Jackson Venice 0 2 1 4 13 

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 

Aardvac 800 Skimmer Storage Bladder 

3,840 500 1 

3 MSRC/Pascagoula Pascagoula 0 2 1 2 13 

WP-1 Skimmer Storage Bladder 

3,017 500 1 

3 MSRC/Pascagoula Pascagoula 0 2 1 2 13 

GT 185 Storage Bladder 

1,371 500 1 

3 MSRC/Pascagoula Pascagoula 0 2 1 2 13 

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 74,446 137,298 

*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. 2012-G02 – “Implementation of Seismic Survey Mitigation Measures and 

Protected Species Observer Program” 

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

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

Species Reporting” 
 

J 

LEASE STIPULATIONS INFORMATION 

Lease Sale # 175: 

Military Area: Green Canyon Block 768 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. Total Fuel Tank 

Storage Capacity 

Max. No. in Area at 

any Time 

Trip Frequency or 

Duration 

Supply Vessel 336,227 gallons 1 2 trips/week 

Helicopter 735.3 gallons 1 10 trips/week 

Crew Vessel 50,000 gallons 1 3 trips/week 

(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: 336,227 gallons 

c. Frequency that fuel supply vessel will visit the facilities: twice 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 133 

miles to GC 768.

(c) Vicinity Map 

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

(d) Produced Liquid Hydrocarbons Transportation Vessels 

Produced liquid hydrocarbons from future flow tests on wells in Green Canyon Block 768 will be 

transported by barge. Flow tests will not exceed 48 hours/well without further approval. 

Transport Method Vessel Capacity Average Volume to be Loaded 

(per transfer) 

No. of Transfers 

(Yearly Average) 

Barge 50,000-130,000 bbls 30,000-40,000 bbls 1-2 

Production from the well will be routed through portable surface well test equipment and safety 

controls aboard the rig. Gas will be flared and liquids (oil & water) will be collected in US Coast 

Guard approved tanks and a barge. The well will be produced / cleaned up and measured using 

various meters through portable surface well test equipment including a separator to a maximum 

rate of 17,500 bpd and 18,000 mcfpd. A three phase separator will be used to analyze water cut 

if present. All liquids (hydrocarbons and water) will then be transferred to a coast guard 

approved barge via tested & approved petroleum transfer hose. We will have a Safe Breakaway 

Coupling (KLAW) installed between the hoses connecting the barge-end and the rig-end. If this 

device parts the KLAW is designed to contain all fluids from both hoses. 
 

 (e) Solid and Liquid Wastes Transportation 

Type of 

Waste 

Composition Total 

Projected 

Amount 

Rate Transport 

Method 

Name/Location of 

Facility 

Disposal 

Method 

Syntheticbased 

drilling 

fluid or 

mud 

Syntheticbased drilling 

muds 

20,000 bbls 10,000 bbls/well Re-use 

and/or 

transport to 

shore in 

DOT 

approved 

containers. 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Station Port Arthur. USLL 

Galveston and Fourchon 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 

disposal facility) or 

USLL (landfarm). 

Cuttings 

wetted with 

syntheticbased muds 

Cuttings coated 

with synthetic 

drilling muds, 

including 

drilled out 

cement 

250-500 bbls 125-250 

bbls/well* 

*An estimated 

5-10% of cuttings 

may be 

transported to 

shore 

Re-use 

and/or 

transport to 

shore in 

DOT 

approved 

containers. 

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). 

Chemical 

product 

waste (well 

treatment 

fluids) 

Ethylene 

glycol 

Methanol 

500 bbls 

125 bbls 

100 bbls/month 

25 bbls/month 

Transport to 

shore in 

DOT 

approved 

containers 

for pick up 

Chemwaste in Sulphur, 

LA and Veolia Port 

Arthur, TX or to Newpark, 

Port Arthur as nonhazardous 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 

6,000 bbls 3,000 bbls/well Transport to 

shore in 

DOT 

approved 

containers 

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 

6,000 bbls 3,000 bbls/well Transport to 

shore in 

DOT 

approved 

containers 

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 

250 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 

537.5 bbls 430 bbls/120 days Transport in 

DOT 

approved 

containers to 

shore for 

pick up 

American Recovery 

Fourchon, LA 

Recycled 

*Total amount assumes 2 wells at 75 days/well 
!

!

!

Green Canyon

Block 768

Nearest

Shoreline

Houma

Port Fourchon

MM II SS SS II SS SS II PP PP II

LL OO UU II SS II AA NN AA

TT EE XX AA SS

127 Miles

139

Miles

165 Miles

88°40'0"W

88°40'0"W

89°20'0"W

89°20'0"W

90°0'0"W

90°0'0"W

90°40'0"W

90°40'0"W

91°20'0"W

91°20'0"W

92°0'0"W

92°0'0"W

92°40'0"W

92°40'0"W

93°20'0"W

93°20'0"W

94°0'0"W

94°0'0"W

94°40'0"W

94°40'0"W

30°40'0"N30°40'0"N

30°0'0"N30°0'0"N

29°20'0"N29°20'0"N

28°40'0"N28°40'0"N

28°0'0"N28°0'0"N

27°20'0"N27°20'0"N

0 25 50 100 Kilometers

Figure 1. Location of Green Canyon Block 768.

Coordinate System: GCS North American 1927

Path: V:\Jobs\2332\MXD\Task30_GC768\2332_T30_GC768_Fig01.mxd

[

Author:

Date Saved: 2/5/2013 4:18:08 PM

Name: 2332_T30_GC768_Fig01

Date: 2/5/2013

Time: 4:20:59 PM

User: gore

Legend

Bathymetry

Block of Interest

Lease Block Boundary

0 25 50 100 Miles
 

L 

ONSHORE SUPPORT FACILITIES INFORMATION

(a) General 

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

to provide supplies and service support for the activities proposed in this EP. 

Name Primary Location(s) Existing/New/Modified 

Anadarko Service Base Fourchon, Louisiana Existing 

Anadarko Service Base (Helicopter base) Houma, LA Existing 

Name *Alternate Locations Existing/New/Modified 

Anadarko Service Base Galveston, TX Existing 

Anadarko Service Base Cameron, LA Existing 

Anadarko Service Base Lake Charles, LA Existing 

Anadarko Service Base Houma, 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.

**Helicopter base only 

(b) Support Base 

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

(c) Waste Disposal 

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

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

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

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

environment. 

Type of 

Waste 

Composition Total 

Projected 

Amount 

Rate Transport 

Method 

Name/Location of 

Facility 

Disposal 

Method 

Syntheticbased 

drilling 

fluid or 

mud 

Syntheticbased drilling 

muds 

20,000 bbls 10,000 bbls/well Re-use 

and/or 

transport to 

shore in 

DOT 

approved 

containers. 

Waste - Port Fourchon, 

LA and on to Newpark 

Fourchon Transfer Station 

#1 & #2. Newpark 

Transfer Station Morgan 

City. Newpark Transfer 

Station Port Arthur. USLL 

Galveston and Fourchon 

Transfer Station. If 

recycled, returned to 

vendor (Bariod or MI). 

Re-used and/or 

recycled; if can’t 

be reused and/or 

recycled the waste 

is disposed of at 

Newpark (injection 

disposal facility) or 

USLL (landfarm). 
 

Cuttings 

wetted with 

syntheticbased muds 

Cuttings coated 

with synthetic 

drilling muds, 

including 

drilled out 

cement 

250-500 bbls 125-250 

bbls/well* 

*An estimated 

5-10% of cuttings 

may be 

transported to 

shore 

Re-use 

and/or 

transport to 

shore in 

DOT 

approved 

containers. 

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). 

Chemical 

product 

waste (well 

treatment 

fluids) 

Ethylene 

glycol 

Methanol 

500 bbls 

125 bbls 

100 bbls/month 

25 bbls/month 

Transport to 

shore in 

DOT 

approved 

containers 

for pick up 

Chemwaste in Sulphur, 

LA and Veolia Port 

Arthur, TX or to Newpark, 

Port Arthur as nonhazardous 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 

6,000 bbls 3,000 bbls/well Transport to 

shore in 

DOT 

approved 

containers 

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 

6,000 bbls 3,000 bbls/well Transport to 

shore in 

DOT 

approved 

containers 

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 

250 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 

537.5 bbls 430 bbls/120 days Transport in 

DOT 

approved 

containers to 

shore for 

pick up 

American Recovery 

Fourchon, LA 

Recycled 

*Total amount assumes 2 wells at 75 days/well 
 

M 

COASTAL ZONE MANAGEMENT ACT INFORMATION 
 

TEXAS COASTAL MANAGEMENT PROGRAM 

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 

235 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 235 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 235 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 235 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 235 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 200 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 200 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 200 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 768 (OCS-G 21817)

Offshore Louisiana

February 2013

Prepared for:

Jill Fowler

Regulatory Analyst

Anadarko Petroleum Corporation

1201 Lake Robbins Drive 

The Woodlands, Texas 77380

Telephone: (832) 636-1554

Prepared by:

CSA Ocean Sciences Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997

Telephone: (772) 219-3000
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page ii

Contents

Page

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

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

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

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

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

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

A.5 Water Intake...................................................................................................................................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) ........................................................................................44

C.3.8 Gulf Sturgeon (Threatened)..............................................................................................45

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

C.3.10 Beach Mice (Endangered).................................................................................................46

C.3.11 Elkhorn Coral (Endangered)..............................................................................................47
Contents

(Continued)

Page

Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page iii

C.4 Coastal and Marine Birds..............................................................................................................47

C.4.1 Marine Birds......................................................................................................................47

C.4.2 Shorebirds and Coastal Nesting Birds...............................................................................50

C.5 Fisheries Resources ......................................................................................................................52

C.5.1 Pelagic Communities and Ichthyoplankton ......................................................................52

C.5.2 Essential Fish Habitat........................................................................................................54

C.6 Archaeological Resources.............................................................................................................58

C.6.1 Shipwreck Sites.................................................................................................................58

C.6.2 Prehistoric Archaeological Sites........................................................................................59

C.7 Coastal Habitats and Protected Areas..........................................................................................60

C.8 Socioeconomic and Other Resources...........................................................................................63

C.8.1 Recreational and Commercial Fishing ..............................................................................63

C.8.2 Public Health and Safety ...................................................................................................64

C.8.3 Employment and Infrastructure .......................................................................................65

C.8.4 Recreation and Tourism....................................................................................................66

C.8.5 Land Use............................................................................................................................67

C.8.6 Other Marine Uses............................................................................................................67

D. Environmental Hazards.........................................................................................68

D.1 Geologic Hazards..........................................................................................................................68

D.2 Severe Weather............................................................................................................................68

D.3 Currents and Waves .....................................................................................................................68

E. Alternatives ..........................................................................................................68

F. Mitigation Measures.............................................................................................69

G. Consultation .........................................................................................................69

H. Preparers..............................................................................................................69

I. References.............................................................................................................69
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page iv

List of Tables

Table Page

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

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

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

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

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

(Modified from: BOEM, 2012b, Appendix C)........................................................................ 13

4 Benthic community data from stations near the lease area in similar water 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: BOEM, 2012b) ........................................................................................................... 61

List of Figures

Figure Page

1 Location of Green Canyon Block 768...................................................................................... 2

2 Bathymetric map of the lease area showing the surface hole locations of wells "B"

and "BB" in Green Canyon Block 768 ................................................................................... 18

3 Location of selected environmental features in relation to the lease area. ........................43
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page v

Acronyms and Abbreviations

ADIOS2 Automated Data Inquiry for Oil Spills 2

Anadarko Anadarko Petroleum Corporation

bbl barrel

BHL bottom hole location

BLPD barrels of liquid per day

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Management,

Regulation and Enforcement

BOP blowout preventer

BOPD barrels of oil per day

B.P. Before Present

BSEE Bureau of Safety and Environmental

Enforcement

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  

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ESA Endangered Species Act

FAD fish‐attracting device

FR Federal Register

FRV fast response vessel

Fugro Fugro Geoconsulting, Inc.

GPS global positioning system

GC Green Canyon

GMFMC Gulf of Mexico Fishery Management

Council

H2S hydrogen sulfide

HAPC Habitat Area of Particular Concern

HOSS high‐volume open sea skimmer

IPF impact‐producing factor

MARPOL International Convention for the

Prevention of Pollution from Ships

MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MMSCFD million standard cubic feet per day

MSRC Marine Spill Response Corporation

MWCC Marine Well Containment Company

NAAQS National Ambient Air Quality

Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric

Administration

NOx nitrogen oxides

NPDES National Pollutant Discharge

Elimination System

NPS National Park Service

NRDA Natural Resource Damage Assessment

NTL Notice to Lessee

NWR National Wildlife Refuge

OBM oil‐based mud

OCS Outer Continental Shelf

OSAT Operational Scientific Advisory Team

OSRA Oil Spill Risk Analysis

OSRB oil spill response barge

OSRP Oil Spill Response Plan

OSRV oil spill response vessel

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

PSV platform supply vessel

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
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 1

Introduction

Anadarko Petroleum Corporation (Anadarko) is submitting a Supplemental Exploration Plan (EP) 

for Green Canyon (GC) Block 768 (GC 768. The EP includes two exploratory wells designated "B"

and "BB". Both the surface hole locations (SHLs) and bottom hole locations (BHLs) for both wells 

will be in Block GC 768. This Environmental Impact Analysis (EIA) provides information on 

the exploratory wells based on the SHLs.

The lease area is 127 miles (204 km) southwest of the nearest shoreline, 139 miles (224 km)

from the onshore support base at Port Fourchon, Louisiana, and 165 miles (265 km) from the 

helicopter base at Houma, Louisiana (Figure 1). Water depth in the project area is predicted to 

be 1,602 m (5,257 ft) The drilling rig is yet to be determined but will be either a dynamically 

positioned (DP) drillship or a DP semisubmersible rig.

This EIA was prepared for submittal to the Bureau of Ocean Energy Management (BOEM) 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; BOEM, 2012a). The analyses from these documents are incorporated here 

by reference. Updated environmental baseline information relative to the Macondo incident 

presented in the Final Supplemental EIS for Central Planning Lease Sale 216/222 (BOEM, 2012b) 

and the Final Supplemental EIS for Western Planning Area Lease Sale 218 (BOEMRE, 2011a) has 

also been incorporated.

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 Final Supplemental EIS for the 

Central Gulf of Mexico Planning Area, BOEM confirmed that "significant changes to the spill 

rates for the entire OCS are not anticipated" (BOEM, 2012b).
Green Canyon Block 768 February 2013

Environmental Impact Analysis-for Supplemental Exploration Plan Page 2

Figure 1. Location of Green Canyon Block 768.
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 3

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 BSEE’s Final 

Drilling Safety Rule (75 Federal Register (FR) 63365) issued following the Macondo incident, the 

baseline risk of a catastrophic blowout is estimated to be about once every 26 years.

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

Response Plan (OSRP) approved on 24 August 2012 for Anadarko and its subsidiaries, Anadarko 

U.S. Offshore Corporation, and Anadarko E&P Company L.P. (Company Numbers 00981, 02219,

and 00148, respectively) in accordance with 30 Code of Federal Regulations (CFR) Part 254.

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.

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

Analysis (EIA).

NTL Title Summary

2012-N06

Guidance to Owners and 

Operators of Offshore Facilities 

Seaward of the Coast Line 

Concerning Regional Oil Spill 

Response Plans 

Provides clarification, guidance, and information for 

preparation of regional Oil Spill Response Plans. 

Recommends description of response strategy for worst 

case discharge (WCD) scenarios to ensure capability to 

respond to oil discharges is both efficient and effective. 

2012-BSEE-G01 Marine Trash and Debris 

Awareness and Elimination

Instructs operators to exercise caution in the handling and 

disposal of small items and packaging materials; requires the 

posting of placards at prominent locations on offshore 

vessels and structures; and mandates a yearly marine trash 

and debris awareness training and certification process.

2012-JOINT-G01

Vessel Strike Avoidance and 

Injured/Dead Protected Species 

Reporting

Recommends protected species identification guides be 

carried on all Gulf of Mexico petroleum vessels and that 

vessel operators and crews maintain a vigilant watch for 

marine mammals. Vessels are to slow down or stop to avoid 

striking protected species, and operators are required to 

report sightings of any injured or dead protected species.

2011-JOINT-G01

Revisions to the List of OCS Blocks 

Requiring Archaeological Resource 

Surveys and Reports

Provides new information of which Outer Continental Shelf

(OCS) blocks require archaeological surveys and reports and 

required survey line spacing in each block. This NTL 

augments NTL 2005-G07.
Table 1. (Continued).

Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 4

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 BOEM

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 

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.

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.

BOEMRE = Bureau of Ocean Energy Management, Regulation and Enforcement; BSEE = Bureau of Safety and 

Environmental Enforcement.
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 5

A. Impact-Producing Factors

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

resources adapted from Form BOEM-142. An "X" indicates that an IPF could reasonably be 

expected to affect a certain resource, and a dash (--) indicates no impact or negligible impact. 

Where there may be an effect, an analysis is provided in Section C. Potential IPFs for the 

proposed activity are listed below and briefly discussed in the following sections.

• Drilling rig presence (including noise 

and lights)

• Physical disturbance to the seafloor

• Air pollutant emissions

• Effluent discharges

• Water intake

• Onshore waste disposal

• Marine debris

• Support vessel and helicopter traffic

• Accidents

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

Two types of exploratory drilling rigs are available for this project: a DP drillship and a 

DP semisubmersible. Both types of drilling rigs use a global positioning system (GPS), specific 

computer software, and sensors in conjunction with their own propellers and thrusters to 

maintain position. Essentially, through satellite navigation, the location of the vessel is precisely 

monitored and thrusters positioned at various locations about the vessel’s hull are activated to 

provide any required station-keeping adjustment. This allows operations at sea where mooring 

or anchoring is not feasible.

The drilling vessel for the wells proposed in this EP will be on site for an estimated 150 days total

(75 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 DP drillships and 

DP 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.
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 6

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

Environmental Resources

Impact-producing Factors

Drilling Rig 

Presence (incl. 

noise & lights)

Physical 

Disturbance 

to Seafloor

Air 

Pollutant 

Emissions

Effluent 

Discharges

Water 

Intake

Onshore 

Waste 

Disposal

Marine 

Debris

Support 

Vessel/Helo 

Traffic

Accidents

Small Fuel 

Spill

Oil Spill 

(WCD)

Physical/Chemical Environment

Air quality and greenhouse gases -- -- --X(9) -- -- -- -- -- X(6) X(6)

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

Seafloor Habitats and Biota

Soft bottom benthic communities -- X -- X -- -- -- -- -- X(6)

High-density deepwater benthic communities -- --(4) -- --(4) -- -- -- -- -- X(6)

Designated topographic features -- --(1) -- --(1) -- -- -- -- -- --

Pinnacle trend area live bottoms -- --(2) -- --(2) -- -- -- -- -- --

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(6)

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

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

Socioeconomic and Other Resources

Recreational and commercial fishing X -- -- -- -- -- -- -- X(6) X(6)

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

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

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

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

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

WCD = worst case discharge.
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Table 2 Footnotes and Applicability:

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

anchors will be on the seafloor within the following:

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

(b) 1,000-m, 1-mi, or 3-mi zone of any topographic feature (submarine bank) protected by the Topographic 

Features Stipulation attached to an Outer Continental Shelf (OCS) lease;

(c) Essential Fish Habitat (EFH) criteria of 500 ft from any no-activity zone; or

(d) Proximity of any submarine bank (500-ft buffer zone) with relief greater than 2 m that is not protected by 

the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or 

no-activity zone. There are no submarine banks in the blocks.

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom 

(Pinnacle Trend) Stipulation attached to an OCS lease.

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

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

(Low-Relief) Stipulation attached to an OCS lease. 

• The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area.

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

• No impacts on high-density deepwater benthic communities are anticipated. There are no features 

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

any drilling mud/cuttings discharge location. 

(5) Exploration or production activities where H2S concentrations greater than 500 ppm might be encountered. 

• GC 768 was classified as "H2S absent" under the initial EP dated 24 October 2001 in accordance with 

30 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 BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such 

blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the 

proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would 

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

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

survey blocks (BOEM, 2012c) and is well beyond the 60-m depth contour used by the BOEM as the 

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

(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals 

or sea turtles or their critical habitats. 

• IPFs that may affect marine mammals, sea turtles, or their critical habitats include drilling rig presence, 

support vessel and helicopter traffic, and accidents. See Section C.

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

• Not applicable.
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A.2 Physical Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP drillships and DP semisubmersibles disturb 

only a very small area of the seafloor around the wellbore (SHL) where the bottom template and 

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

generally about 0.25 ha (0.62 ac) (MMS, 2007a).

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 BOEM 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 Fourchon for recycling and/or disposal at 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, 

ncontact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit 

brine, uncontaminated freshwater and seawater, and ballast water.

A.5 Water Intake

Seawater will be drawn from the ocean for once-through, noncontact 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. GMG290000 does 
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not specify requirements for existing facilities (those that started construction before 

16 July 2006). The DP drilling vessel ultimately selected for this project will be in compliance 

with all cooling water intake structure requirements.

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 approximately 250 bbl over the life of 

this project. The 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 BOEM. For example, BOEM 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, BSEE issued NTL 2012-BSEE-G01, which instructs operators to exercise 

caution in the handling and disposal of small items and packaging materials, requires the posting 

of placards at prominent locations on offshore vessels and structures, and mandates a yearly 

marine trash and debris awareness training and certification process.

A.8 Support Vessel and Helicopter Traffic

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 boat 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 approximately 10 round-trips per week between the drilling rig and the 

heliport. The helicopter will be used to transport personnel and small supplies and will normally 

take the most direct route of travel between the shorebase and the lease area when air traffic 

and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m 

(700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines, 

and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and 

park properties. Additional guidelines and regulations specify that helicopters maintain an 

altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012d).
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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), BOEMRE (2011a), and BOEM (2012b) analyzed 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 BOEM (2012a), 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; BOEM, 2012b). 

The median size for spills <1 bbl is 0.024 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl 

(BOEM, 2012a). 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. Due to its light density, diesel will not sink to the 

seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this 

generally occurs only in coastal areas with high suspended solids loads (National Research 

Council, 2003) and would not be expected to occur to any appreciable degree in offshore waters 

of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring 

microbes (National Oceanic and Atmospheric Administration [NOAA], 2006).

. The fate of a small fuel spill in the lease area would depend on meteorological and 

oceanographic conditions at the time, as well as the effectiveness of spill response activities. 

However, given the open ocean location of the lease area and response actions, it is expected 

that impacts from a small spill would be minimal (BOEMRE, 2011a; BOEM, 2012b).

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

Automated Data Inquiry for Oil Spills 2 (ADIOS2) model. This model uses the physical properties 

of oils in its database to predict the rate of evaporation and dispersion over time, as well as 

changes in the density, viscosity, and water content of the 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 127 miles (204 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 three-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 deep drilling blowout during exploration drilling based on 

U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout 

frequency of 0.0017 per exploratory well for non-North Sea locations (International Association 

of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts 

lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEM is in 

the process of updating these spill frequency estimates to include the recent Macondo event; 

however, significant changes to the spill rates for the entire OCS are not anticipated 

(BOEMRE, 2011a; BOEM, 2012d). As noted in the Introduction, the baseline risk of a 

catastrophic blowout is estimated to be once every 26 years (BSEE Final Drilling Safety Rule,

75 FR 63365).

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

for this EP as 298,799 barrels of oil per day (BOPD). An estimate of 7 to 21 days is required to 

suspend operations on a deepwater Gulf of Mexico well and begin drilling a relief well. This 

assumes 0 to 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 85 days, for a 

total estimated time of 92 to 106 days from time of blowout to finishing the relief well. The 

maximum total volume during a blowout could potentially be 31,672,694 bbl, assuming 

106 days for the maximum duration of a blowout. The detailed analysis of this calculation can be 

found in EP Section H.

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 Final Drilling Safety Rule, which specifies additional

safety measures for OCS activities.
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Spill Trajectory

To address this criticism, a special OSRA run was conducted for the recent BOEM Western and 

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

model did not evaluate the fate of a spill over time periods longer than 30 days, nor did it 

predict the fate of a release that continues over a period of weeks or months, as in the Macondo 

incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the 

chemical composition or biological weathering of oil spills, the spreading and splitting of oil 

spills, or spill response activities. The model does not assume a particular spill size but has 

generally been used by the BOEM to evaluate contact probabilities for spills greater than 

1,000 bbl.

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 launch point nearest to the 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 
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Environmental Impact Analysis for Supplemental Exploration Plan Page 13

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).

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: BOEM, 2012b, 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, State 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. BOEM 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 BOEM (2012b) guidance is provided below.
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This NTL, effective 10 August 2012, provides clarification, guidance, and information on the 

preparation and submittal of regional OSRPs for owners and operators of oil handling, 

storage, or transportation facilities, inclusive of pipelines, located seaward of the coastline. 

It states that lessees, designated operators, and pipeline right-of-way holders are 

responsible for preparation and submission of these plans. Some of the clarifications and 

recommended practices in the NTL are based on lessons learned from the Macondo oil spill 

response.

NTL 2012-N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the 

Coast Line Concerning Regional Oil Spill Response Plans:

NTL 2010-N10 – Statement of Compliance with Applicable Regulations and Evaluation of 

Information Demonstrating Adequate Spill Response and Well Containment Resources: 

This NTL, effective 8 November 2010, applies only to operators conducting operations using 

subsea or surface BOPs on floating facilities. It requires that lessees and operators must 

submit a statement signed by an authorized company official with each well permit 

application indicating that they will conduct all of their authorized activities in compliance 

with all applicable regulations, including the Increased Safety Measures Regulations at 

75 FR 63346. The NTL also informs lessees that BOEMRE will evaluate whether the 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 a Regional OSRP which was approved on 24 August 2012. The OSRP 

provides detailed plans 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 18 June 2010, explains the procedures for the lessee or operator to 

submit supplemental information for new or previously submitted EPs, Development and 

Production Plans, or Development Operations Coordination Documents. The required 

supplemental information includes the following: (1) a description of the blowout scenario 

as required by 30 CFR 254(b) and 254(h); (2) a description of their assumptions and 

calculations used in determining the volume of the WCD required by 30 CFR 254.26; 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 

BOEM announced in NTL 2010-N10, which states that BOEM will review 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 
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• 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 phones, 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 

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 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. Additional CGA equipment can be referenced on the website: 

http://www.cleangulfassoc.com/.

Anadarko also has a contract with the Marine Spill Response Corporation (MSRC) for additional 

spill response equipment. MSRC has a dedicated fleet for the Atlantic/Gulf of Mexico region and 

additional available equipment staged throughout the U.S. The equipment MSRC staged 

throughout the Gulf of Mexico includes 7 oil spill response vessels (OSRVs), 2 fast response 

vessels (FRVs), 5 oil spill response barges (OSRBs), 5 platform supply vessels (PSVs), and 

15 shallow water barges. Various equipment is outfitted with x-band and infrared technology.

MSRC recently completed a large expansion of its resources and capability in the Gulf of Mexico, 

with particular focus on deepwater. The expansion is known as "Deep Blue." Additional MSRC 

capabilities and a complete equipment listing is available on-line at: http://www.msrc.org/.

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.

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 
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 16

hydrogen sulfide (H2S) release. There are no other site-specific issues for the drilling of the wells

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, 

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; BOEM, 2012b).

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 fluids

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-1990s, 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, 2011b).

Vessel Collisions. BOEM data show that from 1996 to 2009 there were 226 OCS-related 

collisions. Most collision mishaps are the result of service vessels colliding with platforms or 

vessel collisions with pipeline risers. Approximately 10% of vessel collisions with platforms in 

the OCS resulted in diesel spills, and in several collision incidents, fires resulted from 

hydrocarbon releases. To date, the largest diesel spill associated with a collision occurred in 

1979 when an anchor-handling boat collided with a drilling platform in the Main Pass lease area, 

spilling 1,500 bbl. Diesel fuel is the product most frequently spilled, but oil, natural gas, 

corrosion inhibitor, hydraulic fluid, and lube oil have also been released as the result of vessel 

collisions. Human error accounted for approximately half of all reported vessel collisions from 

2006 to 2009. As summarized in MMS (2007b) and BOEM (2012b), 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 BOEM-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 the NTL 2010-06 package 

submitted with the exploration plan, as required. The potential for a loss-of-well-control event 

will be minimized by adhering to the requirements of applicable regulations such as the Final 

Drilling Safety Rule and NTL 2010-N10, which specify additional safety measures for 

OCS activities.
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H2S Release. Green Canyon Block 768 was classified as H 2 S absent under the initial EP dated 

24 October 2003. Based on this, no further discussion of H2S is warranted.

B. Affected Environment

The lease area is in the western Gulf of Mexico, 127 miles (204 km) from the nearest shoreline, 

and 139 miles (224 km) from the onshore support base at Port Fourchon, Louisiana (Figure 1).

Based on the site clearance survey conducted by Fugro Geoconsulting, Inc. (Fugro) (2012) water 

depth at the wellsites is anticipated to be 1,602 m (5,257 ft) (Figure 2). There is no evidence of 

significant seafloor or subsurface faulting, fluid expulsion features, or high-density deepwater 

benthic communities near the wellsites (Fugro, 2012).

A detailed description of the regional affected environment, 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 is provided in recent lease sale EISs (MMS, 2007b, 2008; 

BOEM, 2012a). 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 conditions in the offshore waters of the Gulf of Mexico were 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; BOEM, 2012a).

The lease area is located approximately 189 miles (304 km) southwest of the Macondo spill site. 

Based on an analysis of satellite imagery, the surface slick did extend over the lease area and 

there is the possibility that water quality in the lease area was briefly 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 long-term change in water quality conditions in the 

lease area from those predicted in the recent lease sale EISs (MMS, 2007b, 2008; 

BOEMRE, 2011a; BOEM, 2012a,b).
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Figure 2. Bathymetric map of the lease area showing the surface hole locations of wells "B" and "BB" in Green Canyon Block 768.
Green Canyon Block 768 February 2013

Environmental Impact Analysis for Supplemental Exploration Plan Page 19

C. Impact Analysis

This section analyzes the potential direct and indirect impacts of routine activities and accidents. 

Impacts have been analyzed extensively in recent lease sale EISs for the Central and Western 

Gulf of Mexico Planning Areas (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012b) as well as 

the Environmental Assessment for Gulf of Mexico deepwater operations and activities 

(MMS, 2000). The information in these documents is incorporated by reference. Potential 

site-specific issues are addressed in this section.

C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site-specific air quality data for the project area due to the distance from shore. 

Because of the distance from shore-based pollution sources and the lack of sources offshore, air 

quality at the wellsites is expected to be good. The attainment status of Federal OCS waters is 

unclassified because there is no provision in the Clean Air Act for classification of areas outside 

State waters (MMS, 2007b).

As 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).

BOEM 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; BOEM, 2012b).

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 described in recent lease

sale EISs, the incremental contribution to cumulative impacts from activities similar to 

Anadarko’s proposed activities 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 BOEM 

completed the lease sale EISs, the USEPA has adopted a new short-term NAAQS for nitrogen 

dioxide (NO2). 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).

Because of 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 BOEM 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 BOEM is required to notify the National Park Service (NPS) and U.S. Fish and 

Wildlife Service (USFWS) if emissions from proposed projects may affect the Breton Class I area.

Additional review and mitigation measures may be required for sources within 186 miles 

(300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering 

agencies (NPS, 2010). The lease area is approximately 188 miles (303) from the Breton 

Wilderness Area, so air quality impacts on the Wilderness Area are not expected. Anadarko will 

comply with all BOEM 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; 

BOEM, 2012b). 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; 

BOEM, 2012b).

A large oil spill (WCD) could potentially affect air quality by introducing VOCs through 

evaporation from the slick. The extent and persistence of impacts would depend on the 

meteorological and oceanographic conditions at the time and the effectiveness of spill response 

measures. Real-time wind and current data from the project area would be available at the 

time of a spill and would be used to assess the fate and effects of VOCs released. Additional air 

quality impacts could occur if response measures included in situ burning of the floating oil. 

Burning would generate a plume of black smoke and result in emissions of NOx, SOx, CO, and 

PM, as well as greenhouse gases. However, in situ burning would occur only after authorization 

from the USEPA.

Because of the lease area location (127 miles [204 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 189 miles (304 km) from the Macondo spill site. Based 

on the general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface 

slick from that discharge did not extend over the lease area during the spill, and 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; BOEM, 2012b). 

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. 

Because the density of diesel is less than the density of seawater, diesel will not 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 sediments and be removed from the water column (Operational Scientific 

Advisory Team [OSAT], 2010).

Because of the lease area location (127 miles [204 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 project area is approximately 1,602 m (5,257 ft). The seafloor 

around the proposed wellsites is smooth and stable. The immediate regions around the 

proposed well locations show no evidence of seafloor instability within 610 m (2,000 ft) of the 

wellsites. No areas of possible hard bottom or microseepages were seen within 610 m (2,000 ft) 

of any of the wellsites (Fugro, 2012).

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 wellsites. No areas of gaseous sediments or 

possible hydrocarbon seepage were defined in the study area, and the presence of 

chemosynthetic communities is considered negligible (Fugro, 2012).

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 stations in water depths similar to the proposed drilling 

area.
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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 Water Depth

(m)

Abundance

Meiofauna

(individuals/m2)

Macroinfauna

(individuals/m2)

Megafauna

(individuals/ha)

B1 2,256 157,417 1,446 252

GKF 2,460 84,348 737 --

C4 1,446 273,585 3,045 743

MT4 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 (1,602 m [5,257 ft]) typically range from 

approximately 117,000 to 290,000 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

.

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 which includes the Alaminos Canyon, basin and 

nonbasin sites as well as the base of the Sigsbee Escarpment with stations ranging in depth from 

1,600 to 3,008 m. The most abundant species in Zone 3W were the polychaetes Levinsenia 

uncinata, Paraonella monilaris, and Tachytrypane sp. A; the bivalve Heterodonta sp. B; and the 

isopod Macrostylis sp.

Megafaunal densities from nearby stations ranged from 191 to 1,600 individuals/ha. 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 

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 DP semisubmersibles 

disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP 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 approximately 33 miles (53 km)

norththwest of the lease area in GC 287. The nearest identified deep water coral communities 

are in GC 852, 14 miles (23 km) west-southwest of the lease area.

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

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

mud/cuttings discharge locations (Fugro, 2012).

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 DP semisubmersibles 

disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP 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 Fugro (2012) report, there will be no impacts on chemosynthetic or deepwater coral 

communities from this project.

Impacts of Effluent Discharges

The site clearance survey (Fugro, 2012) 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 

blowout are still unknown due to the depth and the 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 by 40 m (50 by 130 ft) was covered by what 

appeared to be a brown flocculent substance (floc). 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. Based on hopanoid petroleum biomarkers from the floc, researchers 

concluded that it contained oil from the Macondo spill. The injured and dead corals were in an 

area where a subsea plume of oil had been documented during the spill in June, 2010; corals 

elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be 

experiencing higher mortality. The research team concluded that the observed coral injuries 

likely resulted from exposure to the subsurface oil plume (White et al., 2012).

C.2.3 Designated Topographic Features

The block is not within or near a designated topographic feature or a no-activity zone as 

identified in NTL 2009-G39. The nearest designated topographic feature is Ship Shoal in 

Ewing Bank Block 945, 56 miles (90 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, 207 miles (333 km) northeast

of 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 246 miles (397 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 
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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 

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

(BOEM, 2012b). The existing consultation recognizes that BOEM-required mitigations and other 

reasonable and prudent measures should reduce the likelihood of impacts from all 

BOEM-authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include 

the West Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of 

beach mouse. Critical habitat has been designated for all of these species as indicated in Table 5

and discussed in individual sections.

Two other coastal species (Bald Eagle and Brown Pelican) are discussed in the MMS (2007b) 

lease sale EIS are no longer listed as endangered or threatened. These are discussed in 

Section C.4.2, Shorebirds and Coastal Nesting Birds.

The sperm whale and five species of sea turtles are the only endangered or threatened species 

likely to occur at or near the lease area. No critical habitat has been designated for these 

species in the Gulf of Mexico.

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right 

whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare 

or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these 

species in the Gulf of Mexico.

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., 2012). No critical habitat for the sperm whale has been designated in the Gulf of Mexico.

The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical 

features such as eddies associated with the Loop Current (Jochens et al., 2008). Sperm whale 

populations in the north-central Gulf of Mexico are present there throughout the year

(Davis et al., 2000). Results of a multi-year tracking study show female sperm whales typically 

concentrated along the upper continental slope between the 200- and 1,000-m (656- and 

3,280-ft) depth contours (Jochens et al., 2008). Male sperm whales were more variable in their 

movements and were documented in water depths greater than 3,000 m (9,843 ft). Generally, 

groups of sperm whales sighted in the Gulf of Mexico during the MMS-funded Sperm Whale 

Seismic Study (SWSS) consisted of mixed-sex groups comprising adult females and immatures, 
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and groups of bachelor males. Typical group size for mixed groups was 10 individuals 

(Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the 

lease area. Movements of satellite-tracked individuals suggest that this area of the Gulf 

continental slope is within the home range of the Gulf of Mexico population (within the 

95% utilization distribution) (Jochens et al., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support 

vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill 

(WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid 

dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the 

mobility of these marine mammals. Compliance with NTL 2012-BSEE-G01 will minimize the 

potential for marine debris-related impacts on sperm whales.

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

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

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

anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from 

marine debris, research, predation and natural mortality, direct harvest, competition for 

resources, loss of prey base due to climate change and ecosystem change, and cable laying.

In the Gulf of Mexico, the impacts from many of these threats are identified as either low or 

unknown (BOEMRE, 2011a; BOEM, 2012b).

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; BOEM, 2012a,b) 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, the BSEE and BOEM issued

NTL 2012-JOINT-G01, which recommends protected species identification training and that 
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vessel operators and crews maintain a vigilant watch for marine mammals and slow down or 

stop their vessel to avoid striking protected species, and requires operators to report sightings 

of any injured or dead protected species. When whales are sighted, vessel operators and crews 

are required to attempt to maintain a distance of 91 m (300 ft) or greater whenever possible. 

Vessel operators are required to reduce vessel speed to 10 knots or less, when safety permits,

when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an 

underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well 

as reduce the chance for disturbing sperm whales.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales. With 

implementation of the mitigation measures in NTL 2012-JOINT-G01, NMFS concluded that the 

likelihood of collisions between vessels and sperm whales would be reduced to insignificant 

levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an 

advantageous response to avoid a potential threat and is not expected to result in any 

significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, 

or have any consequences at the population level. With implementation of the vessel strike 

avoidance measures requirement to maintain a distance of 91 m (300 ft) from sperm whales, 

the NMFS concluded that the potential for harassment of sperm whales would be reduced to 

discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) 

documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an 

altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during 

3 (12%) of 24 sightings. All three reactions consisted of a hasty dive and occurred at less than 

360 m (1,180 ft) lateral distance from the aircraft. Additional reactions were seen when aircraft 

circled certain whales to make further observations. Based on other studies of cetacean 

responses to sound, the authors concluded that the observed reactions to brief overflights by 

the aircraft were short-term and probably of no long-term biological significance.

While flying offshore in the Gulf of Mexico, helicopters maintain altitudes above 213 m (700 ft) 

during transit to and from the working area. In the event that a whale is seen during transit, the 

helicopter will not approach or circle the animals. Although responses are possible (Smultea 

et al., 2008), the NMFS (2007) and BOEM (2012d) 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; BOEMRE, 2011a; BOEM, 2012a,b) 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.
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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 (Marine Mammal Commission [MMC], 2011). However, 

due to the limited areal extent and short duration of water quality impacts from a small fuel 

spill, as well as the mobility of sperm whales, no significant impacts would be expected.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs 

(MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b,d) and by NMFS (2007). For this EP, there 

are no unique site-specific issues with respect to spill impacts on these animals.

Impacts of oil spills on sperm whales can include direct impacts from oil exposure, as well as 

indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and 

dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, 

inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of 

toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from 

the activities and noise of response vessels and aircraft. Complications of the above may lead to 

dysfunction of immune and reproductive systems, physiological stress, declining physical

condition, and death. Behavioral responses can include displacement of animals from prime 

habitat, disruption of social structure, changing prey availability and foraging distribution and/or 

patterns, changing reproductive behavior/productivity, and changing movement patterns or 

migration (MMC, 2011).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury 

or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to reduce 

the potential for striking or disturbing these animals.

C.3.2 West Indian Manatee (Endangered)

Most of the Gulf of Mexico manatee population is located in peninsular Florida (USFWS, 2001). 

Manatee sightings in Louisiana have increased as the species extends its presence farther west 

of Florida in the warmer months (Wilson, 2003). A species description is presented in a recent 

lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).

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

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

area is approximately 127 miles (204 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 
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prior to breaking up. Compliance with NTL 2012-BSEE-G01 will minimize the potential for 

marine debris-related impacts on manatees.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel 

strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). 

To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012-JOINT-G01, which 

recommends protected species identification training and that vessel operators and crews 

maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid 

striking protected species, and requires operators to report sightings of any injured or dead 

protected species. Compliance with 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 relatively low altitudes of 20 to 160 m (66 to 525 ft). Helicopters used in 

support operations maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 

305 m (1,000 ft) over unpopulated areas or across coastlines, and 610 m (2,000 ft) over 

populated areas and sensitive habitats such as wildlife refuges and park properties. In addition, 

guidelines and regulations specify that helicopters maintain an altitude of 305 m (1,000 ft) 

within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). 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, 2011). Direct physical and physiological effects can include skin 

irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; 

inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey 

(or contaminated vegetation, in the case of manatees); and stress from the activities and noise 

of response vessels and aircraft. Complications of the above may lead to dysfunction of immune 

and reproductive systems, physiological stress, declining physical condition, and death. 

Behavioral responses can include displacement of animals from prime habitat, disruption of 

social structure, changing prey availability and foraging distribution and/or patterns, changing 

reproductive behavior/productivity, and changing movement patterns or migration 

(MMC, 2011).

In the event that a large spill reached coastal waters where manatees were present, the level of 

vessel and aircraft activity associated with spill response could disturb manatees and potentially 

result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate 

in accordance with NTL 2012-JOINT-G01 to reduce the potential for striking or disturbing these 

animals, and therefore no significant impacts are expected.

C.3.3 Endangered Mysticete Whales

Five endangered mysticete whales (blue whale, fin whale, humpback whale, North Atlantic right 

whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare 
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or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these 

species in the Gulf of Mexico.

Because of the rare occurrence of these whales in the Gulf of Mexico and the limited scope and 

duration of the project, it is highly unlikely that any endangered mysticete would come into 

contact with any project activities, either routine operations or accidents. NMFS did not include 

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; BOEMRE, 2011a; 

BOEM, 2012a,b,d), 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, including 2 species of 

mysticete whales, 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 

nonendangered cetaceans in the deepwater environment are odontocetes such as the 

pantropical spotted dolphin, spinner dolphin, and Clymene dolphin. A brief summary is 

presented below, and additional information on these groups is presented in a recent lease sale 

EIS (MMS, 2007b).

Mysticete whales. Two species of nonendangered 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.
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Delphinids. Fourteen species of delphinids are known from the Gulf of Mexico, including 

Atlantic spotted dolphin (Stenella frontalis), bottlenose dolphin (Tursiops truncatus), Clymene

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

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

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

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

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 nonendangered cetaceans in the deepwater environment are the pantropical spotted 

dolphin, spinner dolphin, and Clymene dolphin.

Bottlenose dolphins

IPFs potentially affecting nonendangered marine mammals include drilling rig presence, noise, 

and lights; support vessel and helicopter traffic; and two types of accidents–a small fuel spill and 

a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on marine 

mammals due to rapid dispersion, the small area of ocean affected, the intermittent nature of 

the discharges, and the mobility of marine mammals. Compliance with NTL 2012-BSEE-G01 will 

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

. Bottlenose dolphin populations in the northern Gulf of Mexico are 

separated by the NMFS into 37 geographically distinct population units, or stocks, for 

management purposes (Waring et al., 2012). NMFS (2013) has proposed to classify the Gulf of 

Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the Bay, Sound, and 

Estuarine Stocks as strategic stocks, based primarily on the occurrence of an "unusual mortality 

event" of unprecedented size and duration (which began in February 2010 and is ongoing) that 

has affected these stock areas. Carmichael et al. (2012) hypothesized that the unusual number 

of bottlenose dolphin strandings in the northern Gulf of Mexico during this time may have been 

associated with environmental perturbations including sustained cold weather and the 

Macondo spill in 2010 as well as large volumes of cold freshwater discharge in the early months 

of 2011.

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most 

odontocetes (toothed whales and dolphins) use higher frequency sounds than those produced 

by OCS drilling activities (Richardson et al., 1995). Noise intensity associated with drilling is 

relatively weak, and the noise exposure of an individual animal would be transient. There are 

other OCS facilities and activities near the lease area, and the region as a whole has a large 

number of similar sources. Due to the limited scope and short duration of drilling activities, this 

project would represent a small temporary contribution to the overall noise regime, and any 

short-term impacts are not expected to be biologically significant to marine mammal 

populations.

Drilling rig lighting and rig presence are not identified as IPFs for marine mammals in recent 

lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b,d).

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals, and there is also a risk of 

vessel strikes. Data concerning the frequency of vessel strikes are presented in a recent lease 

sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued
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NTL 2012-JOINT-G01, which recommends protected species identification training and that 

vessel operators and crews maintain a vigilant watch for marine mammals and slow down or 

stop their vessel to avoid striking protected species, and requires operators to report sightings 

of any injured or dead protected species. Vessel operators and crews are required to attempt to 

maintain a distance of 91 m (300 ft) or greater when whales are sighted and 45 m (150 ft) when 

small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels 

must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt 

changes in direction until the cetacean has left the area. Vessel operators are required to 

reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of 

cetaceans are observed near an underway vessel, when safety permits. Compliance with 

NTL 2012-JOINT-G01 will minimize the likelihood of vessel strikes as well as reduce the chance 

for disturbing marine mammals, and therefore no significant impacts are expected.

Aircraft traffic also has the potential to disturb marine mammals (Würsig et al., 1998). However, 

while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and 

from the working area. In addition, guidelines and regulations specify that helicopters maintain 

an altitude of 305 m (1,000 ft) within 91 m (300 ft) of marine mammals (BOEM, 2012a,d). 

Maintaining this altitude will minimize the potential for disturbing marine mammals, and no 

significant impacts are expected (BOEM, 2012a,d).

Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008; 

BOEMRE, 2011a; BOEM, 2012a,b), 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, 2011). However, due to the limited areal extent 

and short duration of water quality impacts from a small fuel spill, as well as the mobility of 

marine mammals, no significant impacts would be expected.
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Impacts of a Large Oil Spill (WCD)

Potential spill impacts on marine mammals are discussed in MMS (2000, 2007b, 2008; 

BOEMRE, 2011a; BOEM, 2012a,b). For this EP, there are no unique site-specific issues. Impacts 

of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect 

impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) 

(MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, 

or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; 

ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, 

in the case of manatees); and stress from the activities and noise of response vessels and 

aircraft. Complications of the above may lead to dysfunction of immune and reproductive 

systems, physiological stress, declining physical condition, and death. Behavioral responses can 

include displacement of animals from prime habitat, disruption of social structure, changing 

prey availability and foraging distribution and/or patterns, changing reproductive 

behavior/productivity, and changing movement patterns or migration (MMC, 2011).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response 

could disturb marine mammals and potentially result in vessel strikes, entanglement, or other 

injury or stress. Response vessels would operate in accordance with NTL 2012-JOINT-G01 to 

reduce the potential for striking or disturbing these animals, and therefore no significant 

impacts are expected.

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 2010, 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 Five-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 (BOEM, 2012b).

BOEMRE (2011a) and BOEM (2012b) 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.
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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, 2012);

• Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, 

Tamaulipas, Mexico (NMFS et al., 2011). Kemp’s ridley turtles typically do not nest 

anywhere near the project area, although there have been occasional reports of Kemp’s 

ridleys nesting in Alabama (Share the Beach, 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 2012-BSEE-G01 will minimize the potential for marine debris-related 

impacts on sea turtles.

Impacts of Drilling Rig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that 

may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include 

behavioral disruption and temporary or permanent displacement from the area near the sound 

source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures 

(Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced 

during routine operations. Helicopters and service vessels may also affect sea turtles due to 

machinery noise and/or visual disturbances. The most likely impacts would be short-term 

behavioral changes such as diving and evasive swimming, disruption of activities, or departure 

from the area. Due to the limited scope and short duration of drilling activities, these 

short-term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 

1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they 

are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The 

NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are 

insignificant.

Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles, and there is also a risk of vessel 

strikes. Data show that vessel traffic is one cause of sea turtle mortality in the Gulf of Mexico 

(Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in 

clear weather, they can be difficult to spot from a moving vessel when resting below the water 

surface, during nighttime, or during periods of inclement weather. To reduce the potential for 

vessel strikes, BSEE and BOEM issued NTL 2012-JOINT-G01, which recommends protected 
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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; BOEMRE, 

2011a; BOEM, 2012a,b) 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 

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 127 miles (204 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, 
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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 2012-JOINT-G01 to reduce the 

potential for striking or disturbing these animals, and therefore no significant impacts are 

expected.

C.3.6 Piping Plover (Threatened)

The Piping Plover (Charadrius melodus) is a migratory shorebird that overwinters along the 

southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of 

hunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical 

overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, 

Alabama, and Florida (Figure 3). Piping Plovers inhabit coastal sandy beaches and mudflats, 

feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to 

foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in a 

recent lease sale EIS (MMS, 2007b).

A large oil spill (WCD) is the only IPF potentially affecting Piping Plovers. There are no IPFs 

associated with routine project activities that could affect these birds. A small fuel spill in the 

lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be 

expected to make landfall or reach coastal waters prior to breaking up (see explanation in 

Section A.9.2).
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Figure 3. Location of selected environmental features in relation to the lease area.
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Impacts of a Large Oil Spill (WCD)

The lease area is 127 miles (204 km) from the nearest shorelines inhabited by Piping Plovers 

(Figure 3). The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) 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 nonmigrating 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; BOEM, 2012a). A large oil spill (WCD) is the only IPF potentially affecting 

Whooping Cranes. A small fuel spill in the lease area would also be unlikely to affect Whooping 

Cranes, due to the distance from Aransas NWR. As explained in Section A.9.2, a small fuel spill 

would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill (WCD)

A large oil spill is unlikely to affect Whooping Cranes as the lease area is approximately 

345 miles (556 km) from its critical habitat designated in the Aransas NWR. The revised 

OSRA modeling (BOEM, 2012b) 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.
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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 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; BOEMRE, 2011a; BOEM, 2012b) and by NMFS (2007). For this EP, there are no unique 

site-specific issues with respect to this species.

The lease area is approximately 199 miles (320 km) from the nearest Gulf sturgeon critical 

habitat. The revised OSRA modeling (BOEM, 2012b) 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. 

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 under the 

ESA on 1 April 2003. 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 
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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; BOEMRE, 2011a; BOEM, 2012a) 

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 mouse (Peromyscus polionotus) occur on the barrier 

islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawhatchee, 

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).

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on beach mice are discussed in recent lease sale EISs (MMS, 2007b, 2008; 

BOEMRE, 2011a; BOEM, 2012a). 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 274 miles (440 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 
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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°F and 86°F) and significant water movement. Elkhorn coral was 

once one of the most abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep

in tropical and subtropical waters. In the northern Gulf of Mexico, 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 of Mexico. 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 

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

.
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Trans-Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be 

present in the lease area. Migrant birds may use offshore structures and rigs for resting, 

feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be 

attracted to offshore structures because of the lights and the fish populations that aggregate 

around these structures.

IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; 

support vessel and helicopter traffic; and two types of accidents - a small fuel spill and a large oil 

spill (WCD). Effluent discharges are likely to have negligible impacts on the birds due to rapid 

dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the 

mobility of these animals. Compliance with NTL 2012-BSEE-G01 will minimize the potential for 

marine debris-related impacts on birds.

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 study in the North Sea indicated that rig lighting causes circling behavior in various birds, 

especially on cloudy nights; apparently the birds’ geomagnetic compass is upset by the red part 

of the spectrum from the lights currently in use (Nederlandse Aardolie Maatschappij, 2007). 

The numbers varied greatly, from none at all to some tens of thousands of birds per night per 

rig, with an apparent effect radius of up to 3 miles (5 km). A study in the Gulf of Mexico also 

noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider 

in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and 

foggy days in the Gulf of Mexico versus the North Sea. In laboratory experiments, Poot et al. 

(2008) found the magnetic compass of migratory birds to be wavelength dependent. Migratory 

birds require light from the blue-green part of the spectrum for magnetic compass orientation, 

whereas red light (visible long-wavelength) disrupts their magnetic orientation. They designed a 

field study to test if and how changing light color influenced migrating birds under field 

conditions. During field studies they found that nocturnally migrating birds were disoriented 

and attracted by red and white light (containing visible long-wavelength radiation), whereas 

they were clearly less disoriented by blue and green light (containing less or no visible 

long-wavelength radiation) (Poot et al., 2008). 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.
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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; 

BOEMRE, 2011a; BOEM, 2012 a,b). 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; BOEMRE, 2011a; BOEM, 2012 a,b). For this EP, there are no unique site-specific issues 

with respect to spill impacts on these animals.

BOEM has reexamined the analyses for coastal and marine birds presented in MMS 

(2007b, 2008) and determined that no new information was found that would alter the 

potential impacts on marine and pelagic birds (BOEMRE, 2011a; BOEM, 2012b).

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) 

reported that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted 

seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird 

densities over the open ocean typically are <10 birds/km2

. The number of pelagic birds that 

could be affected in open, offshore waters would depend on the extent and persistence of the 

oil slick.
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The recent Macondo spill provides relevant information about the species of pelagic birds that 

may be affected in the event of a large oil spill. Birds that have been treated for oiling include 

several pelagic species such as the Northern Gannet, Magnificent Frigatebird, and Masked 

Booby (USFWS, 2011). 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 nonendangered 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; BOEMRE, 2011a; BOEM, 2012a).

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, 2012). 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 127 miles (204 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 2012-BSEE-G01

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

Impacts of Support Vessel and Helicopter Traffic

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

Louisiana, where shorebirds and coastal nesting birds may be found. These activities could 

periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands 

that may support feeding, resting, or breeding birds).
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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 USFWS (2011), 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

• Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling
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• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were 

Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, 

unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

While the Macondo spill had direct and indirect impacts to coastal and marine birds, it is 

premature to conclude impacts over a long period (BOEM, 2012b). Modeling of Macondo spill 

related bird impacts is underway by NRDA, but results have not yet been released. 

Antonio et al. (2011) modeled bird-mortality from the Macondo spill showing cumulative 

carcass numbers and mortality rate increasing exponentially from the start of the Macondo spill 

until the mortality rate began to decline after the 97th day of the spill. Note that the collected 

animals would be a small subset of the total number of impacted birds and therefore, the 

collected animals would represent an underestimated measure of the overall impact of the 

Macondo event (BOEM, 2012b).

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or 

wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the 

water, which could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency 

of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they 

can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be 

exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill 

animals immediately, more often it results in lung, liver, and kidney damage, which can lead to 

death. Bird eggs may be damaged if an oiled adult sits on the nest.

As noted above, the Brown Pelican was recently removed from the Federal endangered species 

list. Over 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, 

(USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in 

the event of a catastrophic spill reaching coastal waters. Issues for Brown Pelicans include direct 

contact with oil, disturbance by cleanup activities, and long-term habitat contamination.

C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater 

environment of the northern Gulf of Mexico. The biological oceanography of the region is 

dominated by the influence of the Loop Current, whose surface waters are among the most 

oligotrophic in the world’s oceans. Superimposed on this low-productivity condition are 

productive "hot spots" associated with entrainment of nutrient-rich Mississippi River water and 

mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an 

important role in determining biogeographic patterns and controlling primary productivity in the 

northern Gulf of Mexico (Biggs and Ressler, 2000).
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Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and 

larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae

become part of the planktonic community for various lengths of time (10 to 100 days, 

depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, 

noise, and lights; effluent discharges; water intakes; and two types of accidents -a small fuel spill 

and a large oil spill (WCD).

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish-attracting

device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes 

such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting 

surface structures (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, noncontact 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 
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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; 

BOEMRE, 2011a; BOEM, 2012a,d). For this EP, there are no unique site-specific issues with 

respect to spill impacts.

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will mitigate the potential for impacts on pelagic communities, including 

ichthyoplankton. EP Section H provides detail on spill response measures. Given the open 

ocean location of the lease area, the duration of a small spill and opportunity for impacts to 

occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton. 

Due to the limited areal extent and short duration of water quality impacts, 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.
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The BOEM (2012b) has reexamined the analysis for fish resources and EFH presented in recent 

lease EISs (MMS, 2007a,b), in consideration of the Macondo event. No substantial new 

information was found that would alter the impact conclusions for fish resources and EFH 

presented in MMS (2007a,b).

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management 

Plans for corals and coral reefs, shrimps, stone crab, spiny lobster, reef fishes, coastal migratory 

pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in 

Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). The EFH 

for most of these GMFMC-managed species is on the continental shelf in waters shallower than 

183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef 

fishes, and shrimps. EFH for corals and coral reefs includes some shelf-edge topographic 

features on the Texas-Louisiana OCS, the nearest of which are in GB 127, located approximately 

119 miles (191 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 tuna (adults and juveniles)

• Bigeye thresher shark (all)

• Blue marlin (juveniles, adults)

• Longfin mako shark (all)

• Oceanic whitetip shark (all)

• Skipjack tuna (adults and spawn)

• Swordfish (larvae, juveniles, adults)

• Tiger shark (adults)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, 

adults)

• Whale shark (all)

• Sailfish (adult)

• Silky shark (all)

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. However, NOAA did classify 

the bluefin tuna 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 
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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 BOEM’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some 

EFH requirements may change with the new agreement. Until the new agreement is in place, 

the 1999 Programmatic Consultation with the elements described above will be followed 

(BOEMRE, 2011a; BOEM, 2012b).

Other HAPCs have been identified by the GMFMC (2005). These include the Florida Middle 

Grounds, Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, 

Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico

(Figure 3). The nearest HAPC is Jakkula Bank, located approximately 64 miles (103 km) to the 

north-northwest of the lease area.

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 
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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; BOEMRE, 2011a; 

BOEM, 2012a,d). For this EP, there are no unique site-specific issues with respect to spill 

impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the 

concentrations of petroleum hydrocarbons and their degradation products. The extent and 

persistence of impacts would depend on the meteorological and oceanographic conditions at 

the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate 

of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally 

within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha 

(1.2 to 12 ac), depending on sea state and weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, 

including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the 

lease area. A spill would also produce short-term impact on water quality in the HAPC for 

spawning bluefin tuna, which covers much of the deepwater Gulf of Mexico. The areal extent of 

the affected area would represent a negligible portion of the HAPC.

A small fuel spill would not affect EFH for corals and coral reefs, the nearest EFH being the 

topographic features located approximately 119 miles (191 km) from the lease area along the 

shelf edge south of Louisiana. A small fuel spill would float and dissipate on the sea surface and 

would not contact these features.

Impacts of a Large Oil Spill (WCD)

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008; BOEMRE, 2011a; 

BOEM, 2012a,d). 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 in the subsurface as well. Given the extent of EFH designations in 

the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimps, stone crab, spiny 

lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse 

impacts on water quality and water column biota including phytoplankton, zooplankton, and 

nekton. In coastal waters, sediments could be contaminated and result in persistent 

degradation of the seafloor habitat for managed demersal fish and shellfish species.

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).
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The topographic features, located in GB 127, 56 miles (90 km) north of the lease area, are 

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 BOEM (2012b) 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 BOEM-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 high-probability 

areas (some of which show evidence of impacts from permitted activities prior to their 

discovery), a survey is now required for exploration and development projects.

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks

(BOEM, 2012c). Four sonar contacts interpreted as unidentified debris on the seafloor lie within 

610 m (2,000 ft) of the proposed wellsites. There were no indications of wrecks or other 

archaeological resources detected during the site clearance survey (Fugro, 2012). Anadarko will 

abide by the applicable requirements of NTL 2005-G07, which stipulate that work be stopped at 

the project site if any previously undetected archaeological resource is 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. 
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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 BOEM 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 91 m 

(300 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).

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 between 2,076 to 2,118 m (6,810 to 6,950 ft), the lease area is well beyond 

the 60-m (197-ft) depth contour used by the BOEM as the seaward extent for prehistoric 

archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are 

not 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).
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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; BOEMRE, 2011a; BOEM, 2012a,b,d) 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 

127 miles (204 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 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; 

BOEMRE, 2011a; BOEM, 2012a,b,d). 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. NWRs 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.
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Table 6. Wildlife refuges, wilderness areas, and State and National parks within the geographic 

range of the potential shoreline contacts after 120 days (From: BOEM, 2012b).

County or Parish, State Wildlife Refuge, Wilderness Area, or

State/National Park

Cameron County, Texas

Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park

Andy Bowie County Park 

Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas

Lower Rio Grande Valley National Wildlife Reserve

Laguna Atascosa National Wildlife Reserve 

Padre Island National Seashore

Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore

Laguna Madre Estuarine and Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore

Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas

Laguna Madre Estuarine and Coastal Marine Area

Mustang Island State Park

Lake Corpus Christi State Park

Port Aransas Park

Mission-Aransas National Estuarine Research Reserve

Aransas County, Texas 

Mission-Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas

Mission-Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Matagorda Island State Park

Guadalupe Delta 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
Table 6. (Continued).

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County or Parish, State Wildlife Refuge, Wilderness Area, or

State/National Park

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. 

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; 

BOEMRE, 2011a; BOEM, 2012b).
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C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreational and commercial fishing presented in 

MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill.

No new information was found that would alter the potential impacts on commercial fishing

(BOEMRE, 2011a; BOEM, 2012b).

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 (Pleoticus robustus) are caught by 

trawlers in water depths of about 250 to 550 m (820 to 1,804 ft). Tilefishes (primarily 

Lophalotilus chamaeleonticeps) are caught by bottom longlining in water depths from about 

165 to 450 m (540 to 1,476 ft) (Continental Shelf Associates, Inc., 2002).

Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) 

(Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to 

recreational fishers would be petroleum rigs offshore Texas and Louisiana. Due to the distance 

from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and 

lights). Two types of potential accidents are also addressed below – a small fuel spill and a large 

oil spill (WCD).

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.
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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.

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 127 miles (204 km) from the nearest shoreline (Louisiana)

and nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. 

Response crews would be equipped with appropriate safety equipment to avoid injury and 

health effects. A small fuel spill would not be expected to make landfall or reach coastal waters 

prior to breaking up (see Section A.9.2).
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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, e.g., 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 

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.
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Impacts of a Large Oil Spill (WCD)

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008; 

BOEM, 2012a,b). 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 BOEM (2012b), a recent study 

explored the economic impacts of the Macondo spill on oil and gas industry employment due to 

suspension of deepwater drilling (Inter-Agency Economic Report, 2010). The study indicates 

that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by 

about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs along the 

Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion 

over a six-month period; this direct reduction in spending affected employment in the industries 

that supply the Gulf drilling industry and in all other industries affected by declines in consumer 

and business spending (Inter-Agency Economic Report, 2010).

C.8.4 Recreation and Tourism

BOEM has reexamined the analyses for recreation and tourism presented in MMS (2007b, 2008) 

based on additional information and in consideration of the Macondo oil spill event. No new 

information was found that would alter the potential impacts on recreation and tourism 

(BOEMRE, 2011a; BOEM, 2012b).

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 2012-BSEE-G01 will minimize the chance of trash or debris being lost 

overboard from the drilling rig and subsequently washing up on beaches.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko’s preventative measures during 

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

Anadarko’s OSRP will potentially help mitigate and reduce the potential for impacts. 

EP Section H provides detail on spill response measures. Given the open ocean location of the 

lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are 

no known recreational or tourism activities occurring in the lease area, and as explained in 

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

prior to breaking up.

Impacts of a Large Oil Spill (WCD)

Potential impacts of an oil spill on recreation and tourism are discussed in recent EISs 

(MMS, 2007b, 2008; BOEM, 2012a). For this EP, there are no unique site-specific issues with 

respect to these impacts.
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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 (BOEM, 2012b) as summarized in Section A.9.3 (Table 3), there is a 

17% 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 three-year period at 

$22.7 billion (Oxford Economics, 2010).

C.8.5 Land Use

Land use along the northern Gulf Coast is discussed in recent lease sale EISs (MMS, 2007b, 2008; 

BOEM, 2012a,b). 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 

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 BOEM requirements and lease stipulations to avoid 

impacts on uses of the area by military vessels and aircraft.

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.
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Impacts of a Large Oil Spill (WCD)

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The 

block is not located within any USCG-designated fairway or shipping lane. In the event of a large 

spill requiring numerous response vessels, coordination would be required to manage the vessel 

traffic for safe operations. Anadarko will comply with BOEM 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 site clearance surveys conducted by Fugro (2012) concluded that the wellsites are free of 

any significant geological hazards and are suitable for the proposed activities. See EP Section C

for supporting geological and geophysical information.

D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed 

activities. Extreme weather, including high winds, strong currents, and large waves, was 

considered in the design criteria for the drilling rigs under consideration for this project. High 

winds and limited visibility during a severe storm could disrupt support activities (vessel and 

helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety 

reasons until the storm or weather event passes. In the event of a hurricane, procedures as 

outlined in the Hurricane Evacuation Plan would be adhered to.

D.3 Currents and Waves

Metocean conditions such as sea states, wind speed, ocean currents, etc. will be continuously 

monitored. Under most circumstances, physical oceanographic conditions are not expected to 

have any effect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies 

and intrusions) and large waves were considered in the design criteria for the drilling rigs under 

consideration for this project. High waves during a severe storm could disrupt support activities 

(i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the 

drilling rig for safety reasons until the storm or weather event passes.

E. Alternatives

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

operational options, including the location of the wellsites and the selection of a drilling unit, 

were considered by Anadarko in developing the proposed action.
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F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and 

BOEM lease stipulations and NTLs. The project will comply with all applicable Federal, State, 

and local requirements concerning air pollutant emissions, discharges to water, and solid waste 

disposal. All project activities will be conducted under guidance by 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 Marine Sciences Inc. Contributors included

M. John Thompson (Senior Scientist);

Neal Phillips, Ph.D. (Senior Scientist);

Keith VanGraafeiland (GIS/Remote Sensing Specialist);

Kristen L. Metzger (Library and Information Services Director); and

Kim Dunleavy (Technical Editor).

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