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-07585

Type - Supplemental Exploration Plan

Lease(s) - OCS-G16783 Block - 727 Green Canyon Area OCS-G18421 Block - 683 Green Canyon Area
Operator - Anadarko Petroleum Corporation

Subsea Well F

DP SEMISUBMERSIBLE

Attached is a copy of the subject plan for public comments on issues that should be addressed in an Environmental Assessment.

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

Karen Dunlap
Plan Coordinator Description -

Rig Type - Subject: From: November 13, 2012

# SUPPLEMENTAL EXPLORATION PLAN S-7585

ANADARKO PETROLEUM CORPORATION

GREEN CANYON BLOCKS 727 & 683 OCS-G 18421 & 16783

PUBLIC COPY

RECORD OF CHANGE LOG

Submission Type Date Sent to BOEMRE Summary of Submission Page
Numbers Initial 09/07/2012 Submit Supplemental EP All Amendment 09/17/2012 Revise AQR Screening Question Table 35

Amendment 09/17/2012 Revise Waste Info 54-56, 58-59 Amendment 10/01/2012 Revised Structure Maps
and Cross Sections N/A

Amendment 10/11/2012 Revised G&G Maps N/A Amendment 10/24/2012 Revised G&G Maps N/A Final version of EP Final copy of plan with
all revisions included All

Record of Change Log Record of Change Log 1

# PUBLIC

SUPPLEMENTAL EXPLORATION PLAN

GREEN CANYON BLOCKS 683 & 727 OCS-G 18421 & 16783

OFFSHORE, LOUISIANA

Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380
Contact: Jill Fowler jill.fowler@anadarko.com (832) 636-1554

1 – Hard Copy Confidential
1 – CD Confidential 1 – Hard Copy Public Information
1 – CD Public Information



### September, 2012

## SUPPLEMENTAL EXPLORATION PLAN LEASE OCS-G 18421 & 16783 GREE CANYON BLOCKS 683 & 727

A. Plan Contents

B. General Information

C. Geological, Geophysical

D. Hydrogen Sulfide Information

E. Biological, Physical and Socioeconomic Information

F. Wastes and Discharge Information

G. Air Emissions Information

H. Oil Spill Information

I. Environmental Monitoring Information

J. Lease Stipulations

K. Support Vessels and Aircraft Information

L. Onshore Support Facilities Information

M. Coastal Zone Management Act Information

N. Environmental Impact Analysis

O. Administrative Information

## A PLAN CONTENTS

(a) Plan Information Form

Under this Supplemental Exploration Plan, Anadarko Pe troleum Corporation (Anadark o) proposes to drill and complete one well total in Green Canyon Blocks 683 & 72 7. The well will be drilled using either a Dynamically Positioned (DP) Drillship or DP Semisubmersible drilling rig. Drilling and completion operations for the proposed
well location will utilize a Subsea BOP stack. OCS Pl an Information Form MMS-137 is enclosed as Attachment A1.

(b) Location

Enclosed as Attachment A-2 is a well location plat at a scale of 1 inch = 2000 feet that de picts 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 cont rol, pollution prevention, sa fe 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 re gulations of the Environmental Protection Agency and the U.S. Coast Guard. The appropriate life ra fts, life jackets, ring buoys, etc., as prescribed by the U.S. Coast Guard, will be maintained on the facility at all times.

(d) Storage Tanks and Production Vessels

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

Type of Facility Type Of Storage
Tank Tank Capacity Number Of Tanks Total Capacity Fluid Gravity

(Api) Total Capacity of
all Tanks for

Rig Type

Drillship Fuel Oil Storage
Tank 16,564 bbls 1 16,564 bbls No. 2 Diesel 6 tanks total= 36,595.9 bbls

Fuel Oil Storage
Tank 16,685.5
bbls 1 16,685.5 bbls No. 2 Diesel

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

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

DP Semi Fuel Oil Hull
Tanks 4,541 bbls 2 9,082 bbls No. 2 Diesel 7 tanks total= 16,689 bbls

Fuel Oil Hull
Tanks 3,392 bbls 2 6,784 bbls No. 2 Diesel

Fuel Oil Deck Day
Tank 629 bbls 1 629 bbls No. 2 DieselFuel 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 regula tions regarding pollution prevention and control. The rig ha s 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 dea ling 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 en sures that the necessary actions are taken in a structured, logicalm and timely manner.

Pollution prevention measures includ e 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 moon pool, respectively. To prevent ocean discharge from the drains there is a dedicated drip pan un der the rotary table. The pipe racks, mud pump room, sack store, and drill floor drains go to a holding tank, which is se rved 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-serv ice, oily water separa tor. The containment devices are temporary. They are not meant for perm anent storage of waste. On the rare occasion that they contain wastes, they are pumped, moppe d, or cleaned within a short period of time. The chances of damage to a containment structur e 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 locati ons in both Green Canyon Block 683 and 727. Approval was granted to drill and complete the following well locations under the Initial Exploration Plan (filed by Shell) for Gr een Canyon Block 683 (Plan Control No. N-7797) approved on August 8, 2003:

Well Location Status of Well Location Potential Future Operations

A Used location to drill GC 683 #001
ST02 well. Well has been completed; preparing to place on production. B Well location open. Possible well location for future drilling operations. C Well location open. Possible well location for future drilling operations. D Well location open. Possible well location for future drilling operations. E Well location open. Possible well location for future drilling operations.



### Approval was granted to drill and complete the following well locati ons under the Initial Exploration Plan (filed by Shell) for Gr een Canyon Block 727 (Plan Control No. N-7577) approved on December 24, 2002:

Well Location Status of Well Location Potential Future Operations

A Well location open. Possible well lo cation for future drilling operations. B Well location open. Possible well lo cation for future drilling operations.
C Used location to drill GC 727 #001
well. Well was P&A’d in 2003.

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



### Approval was granted to drill and complete the following well location under the Supplemental Exploration Plan (filed by Anadarko) for Gr een Canyon Block 683 & 727 (Plan Control No. S7509) approved on January 6, 2012:

Well Location Status of Well Location Potential Future Operations

002 Well location open. Possible well lo cation for future drilling operations.MMS FORM MMS-137 (July 2005 – Supersedes all previous editions of form MMS-137, whic h may not be used.) Page 1 of 5 U.S. Department of the Interior Minerals Management Service OCS PLAN INFORMATION FORM OMB Control Number: 1010-0051 OMB Approval Expires: July 31, 2008

General Information

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

Company Name: Anadarko Petroleum Corporation MMS Operator Number: 00981

Address: 1201 Lake Robbins Driv e Contact Person: Jill Fowler

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

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

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

Objective(s): x Oil x Gas Sulphur Salt Onshore Base: Fourchon, LA Distance to Closest Land (Miles): 120
Description of Proposed Activi ties (Mark all that apply)

x Exploration drilling Development drilling

x Well completion Installation of production platform

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

Installation of caisson or platform as well protecti on structure Installation of satellite structure

x Installation of subsea wellheads and/or manifolds Commence production

Installation of lease term pipelines Ot her (Specify and describe)

Have you submitted or do you plan to submit a Conser vation Information Document to accompany this plan? Yes x No

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

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

Do you propose any activities that may disturb an MMS-designated hi gh-probability archaeological area? Yes x No

Have all of the surface locations of your proposed activities been previ ously reviewed and approved by MMS? Yes x No
Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Drill and complete well F in GC 727 01-01-2014 05-29-2014 148

Conduct Well Test 05-30-2014 06-01-2014 2

Description of Drilling Rig Description of Production Platform

Jackup X Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Compliant tower

Semisubmersible Submersible Fixed platform Guyed tower

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

Drilling Rig Name (If Known): Spar Other (Attach Description)
Description of Lease Term Pipelines

From (Facility/Area/Block) To (Facility/Area /Block) Diameter (Inches) Length (Feet)MMS FORM MMS-137 (July 2005 – Supersedes all previous editions of form MMS-137, whic h may not be used.) Page 2 of 5 OCS PLAN INFORMATION FORM Include one copy of this page for each proposed well/structure Proposed Well/Str ucture Location

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

Anchor Radius (if applicable) in feet:
N/A x Yes No

Surface Location Bottom-Hole Location (For Wells)

Lease No. OCS-G 18421

Area Name Green Canyon

Block No. 683

Blockline Departures (in feet) N/S Departure: 574’ FSL

E/W Departure: 7692’ FWL

Lambert X-Y coordinates X: 2,352,012

Y: 9,900,574

Latitude/ Longitude Latitude 27.266644

Longitude 90.809057

Water Depth (Feet): 4,485’

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

Anchor Name
or No. Area Block X Coordinate Y Coordinate Length of Anchor Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =
Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Docume nt submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of informati on unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for prep aring Exploration Plans and Development Operations Coordination Documents. We estimate that burden to average 600 hours per response, or 640 with an accompanying EP, or 690 with an accompanying DP or DOCD, including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the fo rms associated with subpart B. Direct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240.

### B GENERAL INFORMATION

(a) Applications and Permits

Prior to beginning exploration operations the follo wing 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 50,000 bbls per well

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

(c) New or Unusual Technology

Anadarko does not propose to use any new or unusual tec hnology to drill the well proposed in this plan.

(d) Bonding Statement

The bond requirements for the activities and facilities pr oposed in this EP are satisfied by an area-wide bond furnished and maintained according to 30 CFR pa rt 256, subpart I; NTL No. 2000-G16, “Guidelines for General Lease Surety Bonds,” and National N TL 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 Financia l Responsibility for Covered Facilities”.

(f) Deepwater Well Control Statement

Anadarko Petroleum Corporation (Company Number 0098 1) 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 previously approved Green Canyon 727 #2 well is addressed in this blowout scenario since it is the location with the highest potential worst case discharge (WCD) rate for Green Canyon Block 727. A similar approach would be taken in the event of a blowout for the well covered under this plan. Based on NTL No. 2010-N06 guidance, the maximum hydrocarbon discharge for Green Canyon Block 727 is calculated to be 340,281 BOPD.

### Purpose This information provides a generic blowout scenario, additional information regarding any potential oil spill, the measures Anadarko Petr oleum will take to prevent a blowout, and if necessary, promptly respond to manage a blow out scenario if one occurs. The following information is pursuant with 30 CF R 250.213(g), 250.219, 250.250 and NTL No. 2010-N06.

Background This section has been developed to documen t the additional information requirements for Exploration Plans as requ ested by NTL No. 2010-N06.

Information Requirements

Blowout Scenario The GC 727 “2” well will be drilled utilizing a MODU rig with a marine riser and sub-sea BOP. A typical sub-sea wellhead system, conductor, an d surface and intermediate casing program will
be used.

The Blowout Scenario assumes a hydrocarbon in flux occurs from the objective intervals, followed by a well control event. The sub-sea BOP and marine rise r fails, and a blowout occurs
at the seabed. The WCD scenario assumes a 13-5/ 8” x 14” casing string se t, 11-7/8” liner set, and 10-5/8” x 12-1/4” open hole is drilled. The objective sand(s) are the WCD scenario.

Estimated Flow Rate of the Potential Blowout
Category Supplemental EP Type of Activity Drilling Facility Location (area/block) GC Block 727 Facility Designation MODU Distance to Nearest Shoreline (miles) 120 Uncontrolled Blowout (volume per day) 340,281 bbl Type of Fluid(s) Crude Oil- API gravity 28.9

a) Potential for the well to bridge over:

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

b) Measures to enhance the ability to conduct effect ive and early intervention in the event of a
blowout: The likelihood of surface intervention to stop a blowou t is high and is based on the following equipment specific to the MODU that has been contracted to do this drilling program:

 ROV Secondary BOP Control System: The BOP is confirmed to have a ROV Intervention Panel and circuits that have the following attributes:

 Hot stab is capable of closing one set of:

– Blind-Shear Rams (one set)

– Pipe Rams (one set)

– Unlatch the Lower Marine Riser Package ROV hot stab to be function tested in conjunction with the Stump test and tested at the same rate and pressure as the pump installed on the ROV used by the rig.

 BOP panels also can be operated by an ROV from an independent supply boat in the event of a loss-of-rig scenario.

 Deadman/Autoshear Function: The rig is equi pped 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 wo rk. As of September 7, 2012 there were over 23 additional rigs capable of operating under these c onditions in the Gulf of Mexico. A rig which
could be used to drill a relief well is the Transo cean Discoverer Clear Leader which is a drill ship capable of drilling in 12,000’ of wa ter without any constraints. The rig is currently under contract to Chevron and is on location at Walker Ridge Block 677.

There are no nearby platforms from which to drill a relief well.
It is not feasible to drill a relief well from land.

d) Rig constraints:

A rig capable of drilling in 4,500 ft of water with a 15k Stack is required for any relief well operations. The Transocean Discoverer Clear Leader drill ship meets these requirements.

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

An estimate of 7-21 days is required to susp end operations on a deepwater GOM well and begin drilling the relief well. This assumes 0-14 days to su spend current operations on an existing well and 7 days to mobilize and be ready to spud the relie f well. The estimated time to drill the relief well is 125 days, for a total estimated time of 132-146 days fro m time of blowout to finishing the relief well. The drilling days were based on the proposed days to drill the GC 727 #2 well through the objective sands (interval of WCD) with a dditional time added for ranging.

The time estimate provided for the plan well is inclus ive of 'both' drilling 'and' completion operations. As a completion is not typically part of re lief well operations no time has been included for completion operations in the relief well estimate. Therefore the estimated time for a relief well should be less than for the plan well. In additi on, information and learning from the drilling of the original well may provide opportunities to optimi ze drilling performance for relief well operations and thus reduce the required drilling time.f) Assumptions and calculations used in approved or proposed Oil Spill Response Plan:

 The Merlin reservoir simulator and Avalon nodal analysis programs were used to estimate the WCD for this well. Supporting input data was pr eviously submitted with Plan Control No. S7509. At the seafloor, the estimated worst case discharge for the well is 340,281 BOPD based on the objective sand intervals.

 The maximum total volume during a blowout could potentially be 49,681,026 bbl assuming 146 days for the maximum duration of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 340,281 bbl.

g) Measures taken to reduce the likelihood of a 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 i nvolves a multi-team peer review of the well design, shallow hazards, and formation pressure ha zards expected during drilling. This process minimizes the potential for an unplanned well contro l 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 pressu re 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 fo rmation 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 startup preparation work for the rig and crews and the thir d-party technical audit work on the rig and the rig’s well control equipment. This measures the rig’s abi lity to handle an unplanne d well control event and provide assurance that the rig can successfully mitig ate a loss of well control event and prevent it from becoming a blowout scenario.

 Barrier Philosophy : For all well designs, Anadarko requires and uses a redundant barrier philosophy that being two independent tested ba rriers, including one mechanical barrier, across each flow path during well operations.

For the final casing string (or liner if it is the fina l string), there shall be two mechanical barriers in
addition to cement inside the wellbore.

It is also standard practice to c onduct pressure testing, in accordance w ith the law, to confirm integrity on
all relevant barriers.

In addition, all intermediate and production casings re turned to the wellhead w ill be locked down before subsequent wellbore construction proceeds.

 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 ha ve been completely recertified compliant to OEM specifications by a qualified third-party. Prior to commencement of operations, independentthird-party verification will be obtained that the sub-sea BOP is designed for the specific equipment on the rig and this specific well design. 250.416(f)

 BOP and Well Control Equipment Testing : To ensure effectiveness of the BOP and well control equipment, a testing program will be c onducted prior to running the BOP and then during the well operations. This testing pr ogram will provide compliance w ith current federal regulations for pressure and function testi ng and will also provide periodic assurance on the performance of both primary and secondary BOP control systems including actual interface operations with the ROV and the ROV panel.

 Well Control Training and Drills : Anadarko requires that key nominated onshore and offshore positions, including rig contractor personnel, hold a WellCAP or equivalent well control training certificate, renewable every two years for the type of floating drilling operation being conducted. Anadarko also monitors compliance for its personne l with the federal regulations and Sub-Part O for well control training.

A comprehensive program of well control drills will be conducted offshore to ensure readiness to identify and then manage a well control situation and thereb y minimize the potential for a well control event to
lead to a blowout scenario.

h) Arrangements for drilling a relief well

 The conceptual relief well design is similar to the design of the GC 727 #2 well, in that casing weights, grades, and setting poi nts would be identical. A two block wide shallow hazard assessment has been completed (and submitted) for GC Blocks 683 and 727. Site clearance
letters for surface locations in both blocks have been complete d and deemed acceptable for drilling. A surface location southwest of the proposed well GC 727 #2 surface location has
been identified as a suitable SHL for the re lief well. The potential areas for high density chemo-synthetic communities in the study area have been identified and can be avoided. Depending on the nature of the blowout scenario , well geometry, and to tal depth required to intersect the blowout, previously submitted surface locations and/or additional surface
locations would be submitted and all reviewed fo r best suitability for the location of the relief well if needed. The conceptual well design is no t anticipated to take over 2 days to finalize upon initialization.

 Anadarko’s philosophy is to carry adequate inve ntory in stock to drill a complete well(s) from surface to TD. Back-up long-lead equipment equivalent to the original well design will be carried in stock to allow a rapid res ponse. This includes a spare deepwater sub-sea wellhead system and the large OD casing (36”, 28”, 22”, 18”, and 16”) and connectors required. Smaller OD casing (13 5/8”, 11 7/8”, an d 9 7/8”) is considered widely available on the ground in the GOM and would be resourced out of existing inventory or from suppliers as required.

 Existing service agreements will be in place for support services, including drilling fluids, casing running, cementing, ROVs, solids control, mud logging, directional drilling, LWD/MWD, logging, boats , and helicopters.

 Specialist services for range finding to drill the re lief well in close proximity to the original wellbore at the reservoir depth will be provi ded through Vector Magnetics LLC. Sperry Drilling/Halliburton and Schlumberger have in-house personnel to supplement Vector Magnetics LLC under our existing di rectional drilling agreements.

### C GEOLOGICAL AND GEOPHYSICAL INFORMATION

(a) Geological Description

Discussions regarding geologic information are consid ered 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 show ing the location and depth of each proposed well are
enclosed as Attachment C-3.

(e) Shallow Hazards Report

A Shallow Hazards Report prepared by Geoscience Earth & Marine Services, Inc. (GEMS) for Green Canyon Block 683 was previously submitted by She ll Exploration and Production Company (Shell) with their Initial Exploration Plan. Both GEMS and Sh ell have granted Anadarko permission to utilize the report for this plan.

(f) Shallow Hazards Assessment

Shallow Hazards Site Clearance Letter for the propos ed well location in Green Canyon Blocks 683 & 727 will utilize the Site Clearance Letter from the previ ously approved GC 727 #002 location. A copy of the
GC 727 #002 Site Clearance Letter is enclosed as Attachment C-4.

(g) High-resolution Seismic Lines

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

(h) Stratigraphic Column

A generalized stratigraphic column depicting the 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 dept h table is not required per NTL No. 2008-G04.10615 SHADOW WOOD DRIVE
SUITE 200 HOUSTON, TEXAS 77043 Phone: (713) 468-1410 Fax: (713) 468-1438
E-mail: gems@gemsinc.com

Wellsite GC 727-2 July 20, 2011 Project No. 0711-1949

Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380

Attention: Mr. Todd A. Fowler



### Site Clearance Letter Proposed Wellsite GC 727-2 Block 683 (OCS-G-18421) Green Canyon Area
Gulf of Mexico

Anadarko Petroleum Corporation, (Anadarko) plans to drill an exploration well in Block 683 of the Gree n Canyon (GC) area, Gulf of Mexico. This letter addr esses specific seafloor and subsurface geologic conditions to the Top of Salt at a depth of approxi mately 637 ft below the mudline (bml) at the Propos ed Wellsite GC 727-2. The following discussion is bas ed on findings provided within the main body of the geohazard report for Block GC 683 (OCS-G-18421), wh ich was originally submitted to Shell Exploration a nd Production Company (Shell) on April 28, 2003, GEMS Report No. 0103-615 (GEMS, 2003).

The surface location for Proposed Wellsite GC 727-2 is in the south-central portion of GC 683. The proposed location constitutes the newest phase of t he development of the Caesar/Tonga field and lies approximately 185 ft northwest of the existing GC 6 83 #1 location. Anadarko provided the following
coordinates for GC 727-2:

Proposed Wellsite GC 727-2

Spheroid & Datum: Clarke 1866, NAD27 Projection: UTM Zone 15 North, U.S. Survey ft Line Reference Block Calls
GC 683 X: 2,352,025.5 Latitude: 27 ° 15' 59.36446" N Inline: 2361 7,705.5 ft FWL Y: 9,900,518.6 Longitude: 90 ° 48' 32.46723" W Crossline: 4587 518.6 ft FSL

Anadarko will drill this well using a dynamically p ositioned drilling vessel. Our assessment addresse s the seafloor conditions within a 2,000 ft radius around the proposed wellsite location.



### Attachments

The page-size maps and figures accompanying this le tter have been extracted from the main report’s ori ginal maps and 3-D data volume and centered on the propos ed well location.

Map GC 727-2-1: Bathymetry Map Map GC 727-2-2: Seafloor Rendering Map GC 727-2-3: Seafloor Amplitude Rendering Map GC 727-2-4: Geologic Features Map Figure GC 727-2-1: Portion of Inline 2361 and Cross line 4587 Showing Conditions Beneath

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

- 2 - Wellsite GC 727-2

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

Block 683



### NTL Requirements

The following report complies with the Bureau of Oc ean Energy Management, Regulation, and Enforcement (BOEMRE, formerly MMS) Notice to Lessees (NTL’s) 20 08-G05 and 2009-G40 (MMS, 2008a and 2010). The operator will be required to follow NTL’s 2008- G04 and -G06 with respect to an ROV monitoring survey as well as pre- and post-spud ROV visual ins pection surveys (MMS, 2008b and 2008c).

The Federal lease block GC 683 is not considered ar chaeologically significant (MMS, 2008d); however, pursuant to the “Pre-Seabed Disturbance Survey Miti gation” released by the BOEMRE, (BOEMRE, 2011a), an archaeological assessment of high-resolution dat a or video will be required prior to any bottom dis turbing
activities.

Power Spectrum. According to NTL 2008-G05 (MMS, 2008a), 3-D seism ic reflection data may be used for shallow hazard assessments with approval from the B OEMRE, Gulf of Mexico Region. A power spectrum analysis was conducted from the 3-D seismic data cu be licensed to Anadarko to illustrate the data parameters. The power spectrum curve (below) was g enerated within a 500-ft radius of the intersection of the inline and crossline at the proposed wellsite. We converted the amplitude vs. frequency spectrum, generated by the SMT software, to power vs. frequen cy by squaring the amplitude values as described by J. A. Coffeen, 1978.

Power Spectrum Analysis Curve, GC 683, Proposed Wel lsite GC 727-2

The section of data between the seafloor and the To p of Salt is highly fractured and deformed as a result of the shallow salt mass at the proposed wel lsite. The close proximity of the salt has likely contributed to some lower frequency content on the 3-D data.Project No. 0711-1949

- 3 - Wellsite GC 727-2



### Man-Made Features

Numerous wells and pipelines are present within and /or surrounding the area of seismic data coverage (BOEMRE, 2011b). Table 1 provides a summary of the exploration and development wells drilled within
the area.

Table 1: Existing Wells near Proposed Wellsite GC 7 27-2

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

GC 683 001 Kerr McGee Side-Tracked/Completed 185 feet/SE
GC 727 001 Anadarko Petroleum Corp. Temporarily Abandoned 2.3 miles/SW
GC 726 001 Anadarko Petroleum Corp. Side-Tracked 3.4 miles/SW
GC 726 SS001 Anadarko Petroleum Corp. Side-Tracked/Completed 3.4 miles/SW
GC 726 GC 770-1 Anadarko Petroleum Corp. Side-Tracked/Completed 3.4 miles/SW
GC 639 001 Eni US Operating Co. Inc. Drilling Suspe nded 3.6 miles/NE

GC 640 002 Chevron USA Inc. Side-Tracked 4.9 miles/ NE GC 640 PS001 Chevron USA Inc. Side-Tracked/Complete d 4.9 miles/NE
GC 640 PS002 Chevron USA Inc. Completed 4.9 miles/N E

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

GC 640 PS004 Chevron USA Inc. Application for Permit to
Drill 4.9 miles/NE

GC 640 PS005 Chevron USA Inc. Application for Permit to
Drill 4.9 miles/NE

GC 640 PS006 Chevron USA Inc. Application for Permit to
Drill 4.9 miles/NE

GC 640 PS007 Chevron USA Inc. Application for Permit to
Drill 4.9 miles/NE

GC 640 PS008 Chevron USA Inc. By-Passed/Completed 4 .9 miles/NE

GC 640 IS002 Chevron USA Inc. Completed Water Injector Well 5.4 miles/NE

GC 640 IS003 Chevron USA Inc. Application for Permit to
Drill 5.4 miles/NE

GC 640 IS004 Chevron USA Inc. Application for Permit to
Drill 5.4 miles/NE

Several pipelines and associated umbilicals are pre sent throughout the area of 3-D seismic data covera ge. Two 12-inch proposed oil pipelines and a 5-inch pro posed umbilical generally trend northeast-southwest across the central portion of GC 727 which connect the Proposed Wellsite GC 727-2 and the GC 683 #1 we ll with Anadarko’s Constitution Development in GC 680. Two proposed 9-inch pipelines, a proposed 6-inch pipeline, and two proposed 6-inch umbilicals trend southwest-northeast which connects Chevron’s
Production Drill Center South in GC 640 to the Tahi ti Spar in GC 641. BP Exploration and Production, Inc.’s 2-inch fiber optic cable (Segment No. 17364) , trends northeast-southwest, approximately 4.9 mil es south of the proposed location. A 2-inch, north-so uth trending branch (Segment No. 17847) of the BP f iber optic cable extends north of the primary cable rout e, approximately 4.6 miles southeast of the propose d wellsite (BOEMRE, 2011b).



### Wellsite Conditions

The surface location is clear of any constraining g eologic conditions within a 2,000 ft radius circle from the proposed location.Project No. 0711-1949

- 4 - Wellsite GC 727-2

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

### the proposed wellsite location. The water depth at the proposed location is about -4,484 ft (Map GC727-2- 1). The Proposed Wellsite GC 727-2 lies along an expans ive shallow salt ridge approximately 3,800 ft east of Ship Basin. The seafloor in this area is irregular as a result of the numerous fault scarps and the d eformation of the shallow overburden by the underlying salt (M ap GC727-2-2). The seafloor generally dips toward the
west-southwest at about 0.7°. The near-surface sed iments are expected to be normally consolidated cla ys forming a drape over the area.

Deepwater Benthic Communities. There is no indication of fluids or gas venting fro m nearby faults at the seabed. Features or areas that could support high- density deepwater benthic communities are not locat ed within 2,000 ft of the proposed location. The Seaf loor Amplitude Rendering (Map GC727-2-3) shows normal or ambient amplitudes along the seabed at, a nd near, the proposed wellsite.

The closest area of possible seepage is approximate ly 3,000 ft north-northeast of the proposed wellsit e (Maps GC727-2-3 and GC727-2-4). There is a potenti al for deepwater benthic communities surrounding th is

area.
Stratigraphy. Stratigraphic conditions are shown on Figures GC7 27-2-1 and GC727-2-2. The seafloor and near surface sediments at the Proposed Wellsite GC 727-2 are expected to be hemipelagic and pelagic cl ays and silty clays. The stratigraphic section between the seafloor and the Top of Salt is approximately 637 ft thick. The section above the Top of Salt is folded and highly fractured. In general, the sediments b etween the seafloor and 343 ft below mudline (bml), consis ts of hemipelagic silts, clays and mud-rich, mass-transport deposits. Sediments below 343 ft bm l (-4,852 ft bss, below sea surface) to the Top of Salt at about 637 ft bml (-5,147 bsl) are likely composed o f stiff, overconsolidated clays and clay-rich turbi dites. Alternating sand, silt, and clay layers are possibl e within this unit.

Faults. No seafloor faults are expected to be penetrated by the Proposed Wellsite GC 727-2; however, there are several faults near the proposed surface locati on (Figures GC727-2-1 and GC727-2-2). The closest seafloor fault to the proposed wellsite is approxim ately 1,000 ft to the northeast. The fault trends northeastsouthwest and is downthrown to the southeast.

No distinct faults were mapped at the Proposed Well site GC 727-2; however, the stratigraphic unit abov e the Top of Salt is likely to be highly fractured as a r esult of the past motion of the underlying shallow salt structure. Other faults are likely to exist that a re beyond the resolution of the data.

Shallow Gas and Shallow Water Flow. Significant shallow gas is not expected at this wel lsite within the upper 637 ft of sediment (Figures GC727-2-1 and GC7 27-2-2). The potential for shallow water flow at t his well location is considered negligible (Figure GC72 7-2-2).

Shallow Gas. The potential for encountering shallow gas at the Proposed Wellsite GC 727-2 ranges from negligible to low. The well path will not pen etrate any high-amplitude events between the seaflo or and the Top of Salt (637 ft bml), Map GC727-2-4 and Fig ure GC727-2-2. A low potential for encountering shallow gas exists from 343 ft bml to the Top of Sa lt (637 ft bml). An increase in amplitude characte r in places may indicate an increase in minor amounts of gas within possible thin sand layers within this i nterval. There is a negligible potential for encountering sh allow gas between the seafloor and 343 ft bml.

Water flow . There is a negligible potential for shallow wate r flow within the sedimentary section from the seafloor to the Top of Salt (637 ft bml), Figur e GC727-2-2. Any thin sand or silty-sand layers encountered are not expected to be overpressured. Additionally, the potential for an overpressured environment is considerably reduced by faulting and the thin overburden above the shallow salt.Project No. 0711-1949

- 5 - Wellsite GC 727-2



### Closing

The Proposed Exploration Wellsite GC 727-2 in Green Canyon Block 683 appears suitable for exploration drilling operations. The potential for encounterin g thin sand layers increases between 343 ft bml and the Top of Salt (637 ft bml), but we do not anticipate any significant overpressures associated with this interval. In addition, caution is advised as drilling activit ies must avoid existing infrastructure within close proximity of the proposed location.

We appreciate the opportunity to be of service to A nadarko Petroleum Corporation, and look forward to working with Anadarko on future projects.

Sincerely,

GEOSCIENCE EARTH & MARINE SERVICES, INC. ®

Carla Cleveland
Associate Geoscientist

Erin Williams Janes Daniel L. Lanier Project Manager - Senior Geoscientist Vice Pres ident – Geoscience

Attachments (4 Maps and 2 Figures) Distribution: Mr. Todd A. Fowler, Anadarko Petrole um Corporation (6 Copies)Project No. 0711-1949

- 6 - Wellsite GC 727-2 REFERENCES

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011a, Pre-seabed disturbance survey m itigation, released by BOEMRE in March 2011.

Bureau of Ocean Energy Management, Regulation, and Enforcement, 2011b, Free ASCII Data Files, publishe d on the BOEMRE Gulf of Mexico Region Homepage, http://www.gomr.boemre.gov/homepg/pubinfo/freeasci/ freedesc.html

, Accessed July, 2011.

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

Geoscience Earth & Marine Services, Inc. (GEMS), 20 03, Geologic and Stratigraphic Assessment Block 683 , Green Canyon Area, Gulf of Mexico, Project No. 0103-615. Report submitted to Shell Exploration and Producti on Company.

Minerals Management Service, 2008a, Notice to lesse es and operators of federal oil, gas, and sulphur l eases and pipeline right-of-way holders in the outer continental shelf , Gulf of Mexico OCS region, Shallow hazards requir ements: U. S. Department of the Interior, Minerals Management Ser vice, Gulf of Mexico, NTL 2008-G05.

Minerals Management Service, 2008b, Notice to lesse es and operators of federal oil, gas, and sulphur l eases in the outer continental shelf, Gulf of Mexico OCS region, Infor mation Requirements for Exploration Plans and Devel opment Operations Coordination Documents, U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico,
NTL 2008-G04.

Minerals Management Service, 2008c, Notice to lesse es and operators of federal oil, gas, and sulphur l eases in the outer continental shelf, Gulf of Mexico OCS region, Remot ely operated vehicle surveys in deepwater: U. S. De partment of the Interior, Minerals Management Service, Gulf of Mexi co, NTL 2008-G06.

Minerals Management Service, 2008d, Notice to lesse es and operators (NTL) of federal oil and gas lease s and pipeline right-of-way (ROW) holders on the outer continental shelf (OCS), Gulf of Mexico OCS region (GOMR), Rev isions to the list of OCS lease blocks requiring archaeologic al resource surveys and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 20 08-G20.

Minerals Management Service, 2010, Notice to lessee s and operators of federal oil and gas leases in th e outer continental shelf, Gulf of Mexico OCS region, Deepwater benthic communities: U. S. Department of the Interior, Min erals Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27, 2010.2175.0 4587.0 2250.0 4587.0 2325.0 4587.0 2400.0 4587.0 2475.0 4587.0 2550.0 4587.0

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R E L I E M P L I U

A T V A T D E

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A T V A T D E PEAK

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

NORTH SOUTH

Figure GC 727-2-1. Portion of Inline 2361 and Crossline 4587 Showing Conditions Beneath Proposed Wellsite GC 727-2 WEST EAST

Inline 2361

Crossline 4587

TWO-WAY TRAVEL TIME (SEC) PROPOSED WELLSITE GC 727-2

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TROUGH TWO-WAY TRAVEL TIME (SEC) GC 684 GC 683 GC 682

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SALT2361.04500.02361.04575.02361.04650.03750040000425001.7001.8001.9002.0002.1002.2002.3002.4002.5002.6002.7002.8002.9003.0003.1003.2003.3003.400WATERFLOW ANDGASPOTENTIALShallow Water Flow and Gas PotentialHIGH01 230 = NEGLIGIBLE1 = LOW2 = MODERATE3 = HIGHSEAFLOORNEGLIGIBLE

Two-way Travel Time (sec)HorizonLithology/StratigraphyFigure GC 727-2-2. Tophole Prognosis Chart, Proposed Wellsite GC 727-2, Green Canyon Block 683Potential DrillingConstraintsFilename: 11949_fig_GC 727-2_2.cdrProject No. 0711-1949WaterFlowGas3-D Seismic Section ThroughProposed Wellsite GC 727-2X = 2,352,025.5 ft; Y = 9,900,518.6 ftInline 2361 at Crossline 4587WETWT(sec, bml)Depth(ft, bml)Depth(ft, bss)Inline 2361-4,484-4,8523430.137TWT(sec, bss)1.8451.982The seafloor slopes to the west-southwest at 0.7o.There is a negligible potential for high-density deepwaterbenthic communities within 2,000 ft of the surface location.~HORIZONAPROPOSEDWELLSITEGC 727-2RELATIVEAMPLITUDEPeakTroughLine:Trace:HorizontalDistance (ft):TOPOFSALT-5,1476370.2462.091Negligible potential for shallow gas and overpressured sands.Hemipelagic silts and clays with thin mud-rich,mass-transport deposits.Discontinuous, fractured bedding. Predominantlyhard clays and silts interlayered with thin sands.Low potential for shallow gas.Negligible potential for overpressured sands.

### D HYDROGEN SULFIDE INFORMATION

Discussions regarding geologic information are considered proprietary and have been omitted from this public copy of the EP. Anadarko re quests that the area be classified as a "zone where
the absence of H2s has been confirmed.”

### E BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION

(a) Chemosynthetic Communities Report

The seafloor disturbing activities proposed in this plan are in approximately 4,484’ of water. The well will be drilled with a DP Drillship or DP Semisubmersible drilling unit.



### Maps

A map prepared using 3-D seismic data to depi ct bathymetry, seafloor and shallow geological features, and surface location of the propos ed 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 se afloor disturbances.

(b) Topographic Features Map

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

(c) Topographic Features Statement (Shunting)

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

(d) Live Bottoms (Pinnacle Trend) Map

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

(e) Live Bottoms (Low Relief) Map

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

(f) Potentially Sensitive Biological Features



### The activities proposed in this plan are not within 200 feet of any potentia lly sensitive biological features. Therefore, no map is required per NTL No. 2008-G04.(g) Remotely Operated Vehicle (R OV) Monitoring Survey Plan

Green Canyon Blocks 683 and 727 are located within D eepwater Grid Area 10. This grid is considered to have “adequate ROV survey covera ge”, 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 je opardize 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, effec tive May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04, lessees/operators are require d to address site-specific information on the presence of federally listed threatened or endangere d species and critical habitat designated under the ESA and marine mammals protected under the Mari ne Mammal Protection Act (MMPA) in the area of proposes activities under this plan. Currently there are no designated critical habitats fo r 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 Fede rally-listed endangered and threatened species in the lease area and along the northern Gulf coast:

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

Marine Mammals S p erm whale Ph y seter macroce p halus E X -- None West Indian manatee Trichechus manatus latirostris E -- X Florida ( Peninsular ) Blue whale B alaeno p tera musculus E X a -- None Fin whale B alaenoptera physalus E X a -- None Hum p back whale M e g a p tera novaean g liae E X a -- None North Atlantic right whale Eubalaena glacialis E X a -- None Sei whale B alaeno p tera borealis E X a -- None Sea Turtles
Lo gg erhead turtle Caretta caretta T X X None Green turtle Chelonia m y das T, E b X X None Leatherback turtle Dermochelys coriacea E X X None Hawksbill turtle Eretmochel y s imbricata E X X None Kemp’s ridley turtle L epidochelys 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 Refu g e ) 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 Ke y s Invertebrates Elkhorn coral A cro p ora p almata E -- X Flower Garden Banks Terrestrial Mammals Beach mice (Alabama, Choctawhatchee, Perdi d o Key, St. Andrew) Peromyscus polionotus E -- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = endangered; T = threatened.

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

to be present in the lease area.
b The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.The Environmental Impact Analysis in Section N of this plan further discusses potential impacts and mitigation measures related to threatened and endangered species.

(i) Archaeological Report

Green Canyon Blocks 683 and 727 are not located in an area designated as 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 Blocks 683 & 727 well location was previously submitted to BOEM on September 14, 2011 attached to plan Control No. S-7509. 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 Flor ida 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 DISCH ARGE INFORMATION

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

(a) Projected Generated Wastes Type of Waste Composition Projected Amount Treatment/Storage/Disposal Synthetic-based drilling fluids Synthetic-based drilling muds 14,000 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 wettedwith syntheticbased fluids Cuttings coated with synthetic drilling muds/fluids, including drilled

out cement 8,000 bbls/well Treated and discharge
overboard *Note, an estimated 5-10% of cuttings may be transported to shore in DOT approved
containers and on to the base/transfer station if oil still
remains

. Water-based drilling fluids Water based drilling muds (NaCl saturated,
seawater, freshwater, barite) 50,000 bbls/well Discharge overboard or at
seafloor

Cuttings wetted
with water-based
fluids Cuttings coated
with water-based drilling muds/fluids 24,000 bbls/well Discharge overboard

Chemical product waste (well treatment fluids) Ethylene glycol
Methanol 500 bbls total
125 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 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 750,000 ga ls total Chlorinate and dischargebody waste overboard *Domestic Waste Gray water 750,000 gals total Chlorinate and discharge
overboard Deck drainage Platform washings
and rainwater 525,000 bbls 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 1,200 bbls total 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.

(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 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/da y Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor 1,200 bbls 20 bbls/min Discharge at seafloorFire 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 24,000 bbls 1,000 bbls/hr max Discharge overboard

Water-based drilling
fluids 50,000 bbls 1,000 bbls/hr max Discharge overboard or at
seafloor Cuttings wetted with Synthetic-based fluids 8,000 bbls NA Treated and discharge
overboard *Note, an estimated 5-10% of cuttings may be transported to shore in DOT approved containers and on to the base/transfer station if oil
still remains

. Non-pollutant completion fluids 5,000 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.

(c) Modeling Report

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

### G AIR EMISSIONS INFORMATION

(a) Screening Questions

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

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

Are your proposed exploration activities located east of 87.5 W longitude? No Do you expect to encounter H2S at concentrations greater than 20 parts per million (ppm)? No Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? No

Do you propose to burn produced hydrocarbon liquids? No

(b) Emissions Worksheets Air emissions worksheets have been prepared us ing a DP Drillship and DP Semisubmersible drilling units. Air emissions worksheets are available upon request

.

(c) Summary Information



### Air emissions from the undrilled GC 727 #002 well location under previously approved plan Control No. S-7509 is being carried forward in the following tables to reflect Anadarko’s current drilling schedule. No revisions are being requ ested to the previously approved well location under this plan. 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
Amounts 1 (tons) Calculated Exemption
Amounts 2 (tons) Calculated Complex
Total Emission
Amounts 3 (tons) Particulate matter (PM) 77.24 3996.00 77.24 Sulphur dioxide (SO 2 ) 354.33 3996.00 354.33 Nitrogen oxides (NO

x ) 2656.03 3996.00 2656.03 Volatile organic compounds (VOC) 80.55 3996.00 80.55 Carbon monoxide (CO) 585.09 82717.95 585.09

If drilled with a DP Drillship:
Air Pollutant Plan Emission
Amounts 1 (tons) Calculated Exemption Amounts 2 (tons) Calculated Complex
Total Emission Amounts 3 (tons) Particulate matter (PM) 77.99 3996.00 77.99 Sulphur dioxide (SO 2 ) 357.77 3996.00 357.77 Nitrogen oxides (NO

x ) 2681.85 3996.00 2681.85 Volatile organic compounds (VOC) 81.33 3996.00 81.33 Carbon monoxide (CO) 590.72 82717.95 590.72The 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 Cor poration 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 w ith 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.cleangul fassoc.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 Co rporation (MSRC) for spill response equipment. MSRC stages equipm ent 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 Cont ainment Group (HWCG), a combination of the Helix Fast Response System (HFRS) and the co mmon equipment and services. This agreement
allows access to subsea well contai nment and well shut-in equipment.

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

### (iv) Worst-Case Scenario Determination

Category Regional OSRP EP Type of Activity Exploratory Exploratory Facility Location (area/block) GB 346 GC 727

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

Distance to Nearest
Shoreline 118 miles 120 miles

Storage Tanks (total) N/A N/A Flowlines (on facility) N/A N/A Pipelines N/A N/A Uncontrolled Blowout 350,000 bopd** 340,281 bopd Type of Oil(s) Oil Oil API Gravity 30.1 o 28.9 o

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

** The volume denoted in the Regional OSRP is higher than the NTL No. 2010-N06 (256,700 bopd) and BOEMRE (321,108 bopd) calculations approved under EP Plan Control No. N-95 79. Anadarko elected to denote a higher volume in the Regional OSRP for planning purposes to de monstrate equipment respons e capabilities per previous discussions with Rusty Wright.



### Anadarko has determined that the worst-case scen arios from the activities proposed in this Supplemental EP do not supersede the worst-ca se scenario for Garden Banks Block 346.

Since Anadarko has the cap ability to respond to the worst-case spill s cenario included in our Regional OSRP, and since the worst-case scenario s determined for our EP does not replace the worst-case scenario in our 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 discha rge, resulting from the ac tivities proposed in our
EP.

(b) Worst-Case Discharge Volume Assumptions

Worst-case discharge (WCD) calculations and assump tions within this section utilized guidelines and requirements pursuant with NTL No. 2010-N 06. A Supplemental EP (Control No. S-7509) was previously approved for Green Canyon Bl ock 727 on September 14, 2011; the supplemental plan included the informati on necessary to comply with NTL No. 2010-N06. Within the approved plan, the WCD volume for Green Canyon Block 727 was determined to be 340,281 BOPD. The supplemental well location reques ted within this plan does not exceed the previously approved WCD volume for Green Canyon Block 727; therefore, no additional WCD volume assumptions are provided within this plan.

### (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 drilli ng operations at 340,281 BOPD with an API gravity of 28.9 o 

### . A discussion of the blowout scenario from this proposed activity is included within this Supplemen tal EP in accordance with NTL No. 2010-N06.

Land Segment and Resource Identification Modeling

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

Green Canyon Blocks 727 is lo cated within Launch Area 46. According to the BOEMRE OSRAM, the trajectory indicates a 3% probabili ty of potential impact to the shoreline in Cameron and/or Plaquemines Parish, Louisian a. The results are shown in Table H-2.

Cameron and/or Plaquemines Parish are identified as the most probable potential impacted parish or county within the Gulf of Mexico for this op eration. Cameron Parish is located in Louisiana
and includes Cameron Prairie National Wildlife Ref uge (NWR), East Cove Unit (a part of the Cameron Prairie NWR), Lacassine NWR, and Sabine NWR. Plaque mines Parish is also located in Louisiana and includes Delta NWR, Pass-a-L outre Wildlife Management Area (WMA), and
Bohemia State WMA.

Response

Anadarko will make every effort to respond to the worst-case discharge as effectively as possible. Response equipment available to respond to the worst-case discharge and the estimated time of a spill response from oil spill detecti on 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 vol ume at 340,281 BOPD. An AD IOS weathering model was run based on a similar type of oil expected to be produced from this well. Based on this information, approximately 11% (37,431 bbl s) of the initial volume would be evaporated/dispersed within 24 hours.

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

If the conditions are appropriate, and the necessary approvals and permits have been obtained, in-situ burning may be utilized. Based on in -situ burn operations du ring Deepwater Horizon, approximately 5% (15,143 bbls) of the total in itial worst case discharge could be burned.

### Although unlikely in a spill lasting thirty (30) da ys, potential shoreline impact in Cameron and/or Plaquemines Parish, Louisiana could occur de pending on environmental conditions (wind, currents and temperature) at the time of an in cident. Nearshore response may include the use of shoreline boom on beach areas, or protection/sorbent boom on vege tated areas. Surveillance and real time trajectories would aide in determining the most appropriate strategies to respond to a spill.

Table H.3 provides an example of offshore a nd nearshore equipment, response times, and personnel to respond to a spill of 302,850 bbls, which is the estima ted amount that would remain considering natural evaporation/ dispersion at 24 hours. This amount could be further reduced through the application of aeria l and subsea dispersants, and in-situ burning provided such applications/actions were approved.

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

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

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

In the event of a blowout, Anadarko may:

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

2. Assess the damage and attempt to stop the flow at the source, if safe to do so, to reduce the amount of oil discharged. 3. Notify agencies.

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

### adequacy of response equipment capacities based on this continually updated mass
balance.

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

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

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

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

b. Upon approval, mobilize one Basler aircraft and two DC-3 aircrafts from Houma, with surveillance aircraft and spotter. Mobili ze 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 (U SCG SMART Team). Truck additional dispersants from CGA/MSRC stockpile to Houma, if necessary.

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

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

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

a. The CGA HOSS barge, will be positioned in a stationary mode, will be situated downwind and down-current from location fo r long-duration, high-volume skimming. Based on average travel times, the HO SS barge could be on location within approximately 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 encount er rate, boom will be deployed in a V-configuration in front of the HOSS barge to funnel oil to the skimmers. If necessary, temporary barges can be ac tivated to support continuous skimming operations. (These barges arrive on-site at approximately the same time as the HOSS

### barge.) For an on-going release, multiple barges are deployed to provide for continuous off-loading of skimmer storage vess els and shuttling of recovered oil to an onshore waste handling facility. Sufficient barges are available to provide enough temporary storage for continuous recovery operations.

b. CGA’s Fast Response Units (FRU) woul d arrive on-scene between approximately
17-25 hours of the initial release. These sk immers 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 onl y. The HOSS barge can operate continuously, including night operations. Available technology will be considered such as remote sensing devices that will enable 24 hour surveillance, trajecto ries, and planning. All response vessels are designed to be able to remain offshore continuously throughout the response. Even if sea conditions prohibit effective skimming, these resources would remain offshore until skimming operations c ould be commenced again. Safety would remain the first priority.

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

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

a. Implement pre-designated strategies.

b. Identify resources at risk in spill vicinity.

c. Develop/implement appropriate protection tactics.

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

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

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

 Vessels for supporting offshore operations

 Field safety personnel

 Continued surveillance and m onitoring of oil movement

 Helicopter, video cameras

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

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

 Logistics needed to support equipment:

- Staging areas

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

- Fueling facilities

- Decontamination stations

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

- Communications equipm ent and technicians

 Logistics needed to s upport responder personnel

- Medical aid stations

- 

### Safety personnel

- Food

- Berthing

- Additional clothing/safety supplies

- Decontamination stations

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

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

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

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

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

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

ii. API Gravity 28.9  ̊

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

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

v. WCD Total for Drilling Operations for GC 727 (> 10 miles from shore): 340,281 BOPDTable H-2

Trajectory by Land Segment

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

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

3 days 10 days 30 days

Green Canyon

Blocks 727

Drilling (120 miles from shore) G16783 LA 46

Central Planning

Area Matagorda County, TX Brazoria County, TX Galveston County, TX Jefferson County, TX Cameron Parish, LA Vermilion Parish, LA Lafourche Parish, LA Terrebonne Parish, LA Plaquemines Parish, LA --

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3Table H-3WCD Scenario Drilling Activities – Based on a singlewell uncontrolled blowout (120 miles from shore)Green Canyon Block 727340,281 BOPD (initial volume)302,850 BOPD (after evaporation/dispersion)API Gravity 28.9oOffshore Equipment from Spill Detection to EquipmentDeployment Response Time:Green Canyon Block 727Offshore EquipmentOwner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander--------122ASI/Houma Houma00111103HOSS BargeOperatorsTugs43,000 4,000 183CGA/HarveySTARSVOOHarvey1244026131Deep Blue ResponderLFF 100 Brush + OSRV6,600'44"Sea Sentry Boom660'67"LAMOR18,086 4,000 1114 crewMSRC/Fourchon Fourchon0221432138Gulf Coast ResponderTransrec 350 + OSRV5,280'44"Sea Sentry Boom2,640'67"LAMOR10,567 4,000 1114 crewMSRC/Lake Charles Lake Charles0221437143Louisiana ResponderTransrec 350 + OSRV2,640'44"Sea Sentry II Boom5,280'67"LAMOR10,567 4,000 1114 crewMSRC/Fort Jackson Fort Jackson0221434140FRUOperatorsUtility Boat4,251 200 161CGA/InglesideSTARSVOOIngleside0221221125FRUOperatorsUtility Boat4,251 200 161CGA/GalvestonSTARSVOOGalveston0221219123FRUOperatorsUtility Boat4,251 200 161CGA/Lake CharlesSTARSVOOCameron.5221215.5119.5FRUOperatorsUtility Boat4,251 200 161CGA/Morgan CitySTARSVOOMorgan City.5221214.5118.5FRUOperatorsUtility Boat4,251 100 161CGA/HarveySTARSVOOHarvey.5221213117FRUOperatorsUtility Boat8,502 400 2122CGA/LeevilleSTARSVOOLeeville.5221214118Offshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsFRUOperatorsUtility Boat8,502 400 2122CGA/VeniceSTARSVOOVenice0221215120Koseq Skimming ArmsOperatorsVessel w/ storage/hull89,150 10,000 5 sets305CGA/GalvestonSTARSVOOGalveston02211218132Koseq Skimming ArmsOperatorsVessel w/ storage/hull53,490 6,000 3 sets183CGA/LeevilleSTARSVOOLeeville02211214128Koseq Skimming ArmsOperatorsVessel w/ storage/hull17,830 2,000 1 set61CGA/FourchonSTARSVOOFourchon02211213127Koseq Skimming ArmsOperatorsVessel w/ storage/hull35,660 4,000 2 sets122CGA/VeniceSTARSVOOVenice02211214128DBL 101OperatorsTugs-- 107,285 1204K-Sea/Atlantic Venice0242441148DBL 102OperatorsTugs-- 107,285 1204K-Sea/Atlantic Venice0242441148CTCo 2605OperatorsTug-- 20,000 161EMS/Amelia Amelia0244025130CTCo 5001OperatorsTug-- 47,000 161EMS/Amelia Amelia024402513010,000' 42" Auto BoomVOO-- -- 4020 crewCGA/HarveySTARSHarvey.5212131175,000' 42" Auto BoomVOO-- -- 2010 crewCGA/Lake CharlesSTARSCameron.521215.5119.55,000' 42" Auto BoomVOO-- -- 2010 crewCGA/GalvestonSTARSGalveston0212191232,500' 42" Auto BoomVOO-- -- 126 crewCGA/InglesideSTARSIngleside0212211272,500' 42" Auto BoomVOO-- -- 126 crewCGA/PascagoulaSTARSPascagoula0212161206,679' 44" Sea Sentry IIBoomVOO-- -- 2010 crewMSRC/Lake CharlesSTARS Lake Charles0212221261,980' 44" Sea Sentry IIBoomVOO-- -- 126 crewMSRC/Fort JacksonSTARSFort Jackson021222..5126.5Offshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/Persons3,190' 44" Sea Sentry IIBoomVOO-- -- 2010 crewMSRC/PascagoulaSTARS Pascagoula02121912322,400' 42" BoomVOO-- -- 8025 crewAMPOL/New Iberia New Iberia0212171214,800' 42" BoomVOO-- -- 189 crewAMPOL/Harvey Harvey021213117Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/FourchonPHI/FourchonSTARSSpill SiteSpill SiteFourchon111.5111.5------222------333.5Total 316,609 321,270Spill Team Area Responders (STARS) called out by Marine Spill Response Corporation (MSRC)Vessel of Opportunity=VOOEMS=Enterprise Marine ServicesK-Sea=K-Sea Operating PartnershipNearshore Equipment from Spill Detection to Equipment Deployment Response Time: Green Canyon Block 727Nearshore Equipment*Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsBasler Spray AircraftDC 3 Spray AircraftAero Commander----122ASI/Houma Houma00111103Foilex 250 SkimmerStorage Bladder3,977 500 13MSRC/Lake Charles Cameron021215119Foilex 250 SkimmerStorage Bladder3,977 500 13MSRC/Fort Jackson Venice021413119SWS EgmopolOperators3,000 100 13CGA/GalvestonSTARSGalveston021210013SWS EgmopolOperators3,000 100 13CGA/Morgan CitySTARSMorgan City.521212015SWS MarcoOperators3,588 34 13CGA/LeevilleSTARSLeeville.521211014SWS MarcoOperators3,588 20 13CGA/Lake CharlesSTARSCameron.52128011SWS MarcoOperators3,588 34 13CGA/VeniceSTARSVenice.52121001356' Nearshore SkimmerOperators21,500 250 14CGA/Morgan CitySTARSMorgan City.521213016R/V Grand BayOperators5,000 65 13CGA/VeniceSTARSVenice.522.58010.5R/V RW ArmstrongOperators5,000 65 13CGA/LeevilleSTARSLeeville.522.5709.5R/V Bastian BayOperators5,000 65 13CGA/Lake CharlesSTARSCameron.522.511.5014R/V Timbalier BayOperators5,000 65 13CGA/GalvestonSTARSGalveston022.512014.5CTCo2603OperatorsTug-- 25,000 161EMS/Amelia Amelia0244020125CTCo 2604OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244020125CTCo 2606OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244020125CTCo 2607OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125CTCo 2608OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125Nearshore Equipment, cont.*Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/PersonsCTCo 2609OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125Aardvac 800 SkimmerStorage Bladder3,840 500 13MSRC/Pascagoula Pascagoula021213016WP-1 SkimmerStorage Bladder3,017 500 13MSRC/Pascagoula Pascagoula021213016GT 185Storage Bladder1,371 500 13MSRC/Pascagoula Pascagoula0212130162,000' Beach Boom -- -- 6 CGA/Galveston Galveston 0 1 2 8 2 131,000' Beach Boom -- -- 4 CGA/Ingleside Ingleside 0 1 2 10 2 152,000' Beach Boom -- -- 6 CGA/Pascagoula Pascagoula 0 1 2 6 2 1110,000' 18" BoomVOO-- -- 10/41Oil Mop/New Iberia New Iberia02114.539.510,000' 18" BoomVOO-- -- 10/41Oil Mop/Houston Houston12118.75313.7510,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Arthur Port Arthur02117.25312.2510,000' 18" BoomVOO-- -- 104 crewOil Mop/Houma Fourchon.52113.538.510,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Allen Port Allen02114.539.520,000' 18" BoomVOO-- -- 208 crewOil Mop/Belle Chasse Venice.5211361115,000' 18" BoomVOO-- -- 146 crewOil Mop/Gretna Gretna02114410Wildlife Support Trailer -- -- 1/ 2 crew CGA/Harvey Harvey .5 1 2 3 3 9Bird Scare Cannons -- -- 2 CGA/Venice Venice .5 1 2 3.25 2 8.25Bird Scare Cannons -- -- 1CGA/Galveston Galveston .5 1 2 8.25 2 13.25Bird Scare Cannons -- -- 1CGA/Ingleside Ingleside .5 1 2 10 2 15Bird Scare Cannons -- -- 2CGA/Lake Charles Cameron .5 1 2 5.25 2 10.25Bird Scare Cannons -- -- 2CGA/Pascagoula Pascagoula .5 1 2 5 2 10Bird Scare Cannons -- -- 2CGA/Harvey Harvey .5 1 2 4 2 9Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/HoumaPHI/HoumaSTARSSpill SiteSpill SiteFourchon111.5111.5------1.51.52------2.52.53.5Total 74,446 137,298*Some equipment may be used offshoreup to approximately 25 miles from shoreH-3 (continued)

Operational Limitations of Response Equipment

 HOSS Barge–8 foot seas

 Fast Response Unit (FRU)–8 foot seas

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

 Boom–3 foot seas, 20 knot winds

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

### I Environmental Monitoring and Envi ronmental Mitigation Measures

(a) Monitoring

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

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

(b) Incidental Takes

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

Anadarko will operate in accordance with applicable regulations, including:

NTL No. 2007-G02 – “Implementation of Se ismic Survey Mitigation Measures and Protected Species Observer Program”
BSEE NTL No. 2012-G01 “Marine Trash and De bris Awareness and Elimination”, and
JOINT NTL No. 2012-G01 “Vessel Strike A voidance and Injured/Dead Protected Species Reporting”

### J LEASE STIPULATIONS INFORMATION

Lease Sale # 166:

Military Area: Green Canyon Block 683 is loca ted within Military Warning Area W-92. Anadarko will contact the Naval Air Station, Air Operations Department, New Orleans,
Louisiana in order to coordi nate and control the electroma gnetic emissions during these proposed operations.

Lease Sale # 157:

Military Area: Green Canyon Block 727 is loca ted within Military Warning Area W-92. Anadarko will contact the Naval Air Station, Air Operations Department, New Orleans,
Louisiana in order to coordi nate and control the electroma gnetic 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 Tug Boats 218,300 gallons 1-2 Duration of operation Anchor Handling Vessel 450,698 gallons 1-2 Duration of operation

(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 125
miles to GC 683/727.

(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 Blocks 683 & 727 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 ph ase separator will be used to analyze water cut if present. All liquids (hydrocarbons and wate r) will then be transferred to a coast guard approved barge via tested & approved petroleum tr ansfer hose. We will have a Safe Breakaway Coupling (KLAW) installed between the hoses conn ecting 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 Synthetic- based drilling muds 14,000 bbls 14,000
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 containingsyntheticbased mud Cuttings coated
with ester-based synthetic drilling
muds 400-800 bbls 400-800
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
non-hazardous waste. Can be
returned to
vendor and/or
used at another facility; MEG
is solidified and disposed
of in a landfill.
Methanol is
incinerated or
used for fuels blending.

Completion
fluids Brine, spent acid, prop sand, debris 3,000 bbls 3,000
bbls/well Transport to shore in
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 3,000 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 538 bbls 430 bbls/120 days Transport in
DOT approved
containers to
shore for pick up American Recovery Fourchon,
LA Recycled



### *Total amount assumes 1 well at 150 days/wellGreen Canyon Blocks 683 and 727September 2012Environmental Impact AnalysisPage 3Figure 1. Location of Green Canyon Blocks 683 and 727.

### L ONSHORE SUPPORT FACILITIES INFORMATION

(a) General

Per NTL No. 2008-G04, the following tables reflect the onshore facilities Anadarko 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 expans ion 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 th e 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 th e 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 14,000 bbls 14,000
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 containing synthetic-based
mud Cuttings
coated with
ester-based synthetic drilling muds 400-800 bbls 400-800
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 non-hazardous waste. Can be returned
to vendor and/or
used at another facility; MEG is
solidified and disposed of in a
landfill.
Methanol is
incinerated or
used for fuels blending. Completion
fluids Brine, spent acid, prop sand, debris 3,000 bbls 3,000
bbls/well Transport to shore in 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 3,000 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 538 bbls 430 bbls/120 days Transport in DOT approved
containers to shore for pick

up American Recovery Fourchon, LA Recycled

*Total amount assumes 1 well at 150 days/well

### M COASTAL ZONE MANAGEM ENT ACT INFORMATION

### TEXAS COASTAL MANAGEMENT PROGRAM

The following is an evaluation that includes findi ngs 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. Th e proposed activities are located approximately 230 miles from the Texas shoreline; therefore we expect no adverse impacts to CNRAs or beach access and use rights of the public. All activities sh all 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 expans ion of existing facilities in the coastal zone are proposed in the attached plan, therefore, no adver se 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 n ecessary. The best practical techniques shall be utilized to prevent the release of pollutants or t oxic 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, th e proposed activities are 230 miles from shore; therefore no damages to natural resources are exp ected as the result of an unauthorized discharge
of oil into coastal waters.

(Category 6) Discharge of Municipal and Industria l Waste Water to Coastal Waters

No discharges from the proposed activities will o ccur in coastal waters. The proposed activities are 230 miles from shore; therefore there will be no effect on coastal waters.(Category 8) Development in Critical Areas

None of the proposed activities will occur in a criti cal area; therefore no effects to Texas’ coastal zone are expected. The activity will not jeopardi ze 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 vi olation 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 pr oposed 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 ma terial is proposed; therefore no adverse effects to coastal waters, submerged lands, critical area s, 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 im pact 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 transpor tation 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 th e proposed activities are not expected to have significant impacts on onshore air quality becau se of the prevailing atmospheric conditions, emission heights, emission rates, and the dist ance of these emissions from the coastline. Theproposed activities will occur approximately 2 30 miles from shore and will be within the exemption limits set by BOEM, therefore, no im pacts to Texas’ coastal zone is expected.

(Category 18) Appropriations of Water

The proposed activities do not include the impoundment or diversion of state water, therefore, no impacts to Texas’ coastal zone is expected.

(Category 20) Marine Fishery Management

The proposed activities are located approximately 230 miles from shore and are not expected to have any effect on marine fishery management or fishery migratory patterns within waters in the
coastal zone of Texas.

(Category 22)
Administrative Policies

The necessary information for app licable agencies to make an informed decision on the proposed activities has been provided In conclusion, all activ ities 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 M ANAGEMENT ACT INFORMATION

As authorized by the Federal Coastal Zone Management Act (CZMA), The State of Mississippi developed a Coastal Management Pr ogram (CMP) to allow for the review of proposed Federal license and perm it activities affecting any coasta l use or resources, in or
outside of the Missi ssippi Coastal Zone.

The OCS related oil and gas exploratory a nd development activities having potential impact on the Mississippi Coastal Zone are based on the location of the proposed facilities, access to those sites, best practic al techniques for drilling locations, drilling equipment guidelines for the prevention of adverse environmental effects, effective environmental protection, emergenc y 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 reaso nable 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 base d out of Fourchon, Louisi ana. The activities will not provide any industrial expansion on the coastal area of Mississippi. Therefore Mississippi coastal areas will be cons erved for water dependent industry.

Goal 2: To favor the preservation of the coastal wetlands and ecosystems, except where a specific alteration of specific coasta l wetlands would serve a higher public interest in compliance with the public pur poses of the public trust in which the
coastal wetlands are held.

Goal 2 is addressed in Section N, Environm ental Impact Analysis. The nearest proposed
activities will be 195 miles fr om the Mississippi coast.

Goal 3: To protect, propagate and conserve the state’s seafood and aquatic life in
connection with the revitalization of the se afood industry of the State of Mississippi.

Goal 3 is addressed in Section N, Environm ental Impact Analysis. Little impact to the seafood industry can be expected due to th e activities occurring 195 miles from the Mississippi coast.

Goal 4: To conserve the air and waters of the state, and to protect, maintain and improve the quality thereof for public use, fo r the propagation of wildlife, fish and aquatic life, and for domestic, agricultu ral, industrial, recreational and other legitimate beneficial uses.

Goal 4 is addressed in Section B, Gene ral Information, Sectio n G, Air Emissions Information, and Section N, Environmental Impact Analysis.

### Goal 5: To put to be neficial use to the fullest extent of which they are capable the water resources of the state, and to p revent 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 OC S will be conducted in accordance with our Regional Oil Spill Response Plan refere nced in Section H of this plan.

Goal 6: To preserve the stat e’s historical and archaeological resources, to prevent their destruction, and to enhance these resources wherever possible.

Goal 6 is addressed in Section E, Biologica l, Physical and Socioeconomic Information, and Section N, Environmental Impact Analysis.

Goal 7: To encourage the preservation of na tural 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 In formation, and Section N, Environmental Impact Analysis.

Goal 8: To assist local governments in the pr ovision of public facilities services in a manner consistent with the coastal program.

As the proposed activities ar e located 195 miles from the Mi ssissippi coast and are based out of a shorebase in Fourchon, Louisiana, local governments should not be affected.

### N ENVIRONMENTAL IMPACT ANALYSIS

# Environmental Impact Analysis

SUPPLEMENTAL EXPLORATION PLAN

for Green Canyon Block 683 (OCS

- G 18421 ) and

Green Canyon Block 727 (OCS

- G 16783 )

Offshore Louisiana

September 201 2

Prepared for:

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

Telephone: (832) 636

- 1554

Prepared by:

CSA International, Inc.

8502 SW Kansas Avenue

Stuart, Florida 34997 Telephone: (772) 219

- 3000Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page ii 

## Contents

Page



### Introduction

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

A. Impact

- Producing Factors

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

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

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

A.2 Physical Disturbance to the Seafloor

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

A.3 Air Pollutant Emissio ns

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

A.4 Effluent Discharges

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

A.5 Water Intake

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

A.6 Onshore Waste Disposal

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

A.7 Marine Debris

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

A.8 Support Vessel and Helicopter Traffic

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

A.9 Accidents

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

A.9.1 Types of Accidents Evaluated

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

A.9.2 Small Fuel Spill

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

A.9.3 Crude Oil Spill (Worst Case Discharge)

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

A.9.4 Other Accidents Not Analyzed in Detail

................................ ................................ ............ 15



### B. Affected Environment

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

C. Impact Analysis

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

C.1 Physical/Chemical Environment

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

C.1.1 Air Quality

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

C.1.2 Water Quality

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

C.2 Seafloor Habitats and Biota

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

C.2.1 Soft Bottom Benthic Communities

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

C.2.2 High

- Density Deepwater Benthic Communities

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

C.2.3 Designated Topographic Features

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

C.2.4 Pinnacle Trend Area Live Bottoms

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

C.2.5 Eastern Gulf Live Bottoms

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

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

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

C.3.1 Sperm Whale (Endangered)

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

C.3.2 West Indian Manatee (Endangered)

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

C.3.3 Endangered Mysticete Whales

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

C.3.4 Non

- Endangered Marine Mammals (Protected)

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

C.3.5 Sea Turtles (Endangered/Threatened)

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

C.3.6 Piping Plover (Threatened)

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

C.3.7 Whooping Crane (Endangered)

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

C.3.8 Gulf Sturgeon (Threatened)

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

C.3.9 Smalltooth Sawfish (Endangered)

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

C.3.10 Beach Mice (Endangered)

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

C.3.11 Elkhorn Coral (Endangered)

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

## Contents
( C ontinued)

Page

Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page iii C.4 Coastal and Marine Birds

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

C.4.1 Marine Birds

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

C.4.2 Shorebirds and Coastal Nesting Birds

................................ ................................ ............... 49

C.5 Fisheries Resources

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

C.5.1 Pelagic Communities and Ichthyoplankton

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

C.5.2 Essential Fish Habitat

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

C.6 Archaeological Resources

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

C.6.1 Shipwreck Sites

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

C.6.2 Prehistoric Archaeological Sites

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

C.7 Coastal Habitats and Protected Areas

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

C.8 Socioeconomic and Other Resources

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

C.8.1 Recreational and Commercial Fishing

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

C.8.2 Public Health and Safety

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

C.8.3 Employment and Infrastructure

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

C.8.4 Recreation and Tourism

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

C.8.5 Land Use

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

C.8.6 Other Marine Uses

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



### D. Environmental Hazards

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

D.1 Geologic Hazards

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

D.2 Severe Weather

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

D.3 Currents and Waves

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



### E. Alternatives

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

F. Mitigation Measures

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

G. Consultation

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

H. Preparers

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

I. References

................................ ................................ ................................ ............. 68Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page iv 

## List of Tables

Table Page

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

................................ ................................ ................................ ......................... 4

2 Matrix of impact

- producing factors and affected environmental resources

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

3 Conditional probabi lities 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, 201 2 , Appendix C)

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

4 Benthic community data from stations near the lease area and in greater water depths and more distant stations in more similar depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology S tudy (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 W ildlife refuges, wilderness areas, and state and national parks within the geographic range of the potential shoreline contacts afte r 120 days (From: BOEMRE, 2011)

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



## List of Figures

Figure Page

1 Location of Green Canyon Blocks 683 and 727

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

2 Bathymetric map of the lease area showing the surface hole location (SHL) and bottom hole location (BHL) of GC 727 Well “F”

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

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

........................ 43Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page v 

## Acronyms and Abbreviations

ADIOS Automated Data Inquiry for Oil Spills
bbl barrel

BHL bottom hole location

BLPD barrels of liquid per day

BOEM Bureau of Ocean Energy Management

BOEMRE Bureau of Ocean Energy Managem ent, 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.

CH 4 methane

CO carbon m onoxide

CO 2 carbon dioxide

CFR Code of Federal Regulations

CGA Clean Gulf Associates

DP dynamically positioned

EP Exploration Plan

EA Environmental Assessment

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ESA Endangered Species Act

EW Ewing Bank

FAD fish

- attracting device

FR Federal Register

GC Green Canyon

GPS global positioning system

GMFMC Gulf of Mexico Fishery Management
Council

H 2 S hydrogen sulfide

HAPC Habitat Area of P articular Concern

HFRS Helix Fast Response System

HOSS high

- volume open sea skimmer

HWCG Helix Well Containment Group

IPF impact

- producing factor MARPOL International Convention for the Prevention of Pollution from Ships

MMC Marine Mammal Commission

MMPA M arine Mammal Protection Act

MMS Minerals Management Service

MMSCFD million standard cubic feet per day

MWCC Marine Well Containment Company
NAAQS National Ambient Air Quality
Standards

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmosp heric
Administration

NO x nitrogen oxides

NPDES National Pollutant Discharge Elimination System

NPS National Park Service

NRC National Response Corporation

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

OSRP Oil Spill Response Plan

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

SBF syntheti c

- based fluid

SBM synthetic

- based mud

SHL surface hole location

SO x 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 c ase dischargeGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 1 

## Introduction

Anadarko Petroleum Corporation (Anadarko) is submitting a Supplemental Exploration Plan (EP)
for Green Canyon Blocks 683 and 727 (GC 683 and 727)

. The EP includes one well designated

GC 727 Well " F " to be drilled and completed with the surface hole location (SHL ) in the south

central portion of GC 683 and bottom hol e location (BHL) in GC 727

. This E nvironmental I mpact Analysis (EIA) provides information on the exploratory well based on the SHL and BHL.

The lease area is 120 miles ( 194 km) south of the nearest shoreline, 131 miles ( 211 km) from the onshore support base at Port Fourchon, Louisiana, and 159 miles ( 259 km) from the helicopter base at Houma, Louisiana ( Figure 1 ). Water depth at GC 727 Well "F" is 1,367 m (4,484 ft)

. The drilling rig is yet to be determined but will be either a dynamically positioned (DP) drillship or a
DP semisubmersible

.

This EIA was prepared for submittal to the Bureau of Ocean Energy Management, Regulation
and Enfor cement ( BOEMRE , formerly Minerals Management Service [MMS] ) in accordance with applicable regulations, and is a project

- and site

- specific analysis of Anadarko ’s planned

activities . As specified in the Notice to Lessees and Operators ( NTL ) 2008

- G04, an EI A is a project

- specific analysis that focuses on the impacts of a specific plan to the extent feasible. Potential impacts have been analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the Outer Continental Shelf ( OCS ) Oil and Gas Leasing Program (MMS, 2007a) and in lease sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008) . The analyses from these documents are incorporated here by reference. Also incorporated by reference are the pos t

- Macondo incident Draft Supplemental EIS for the Central Planning Area and Final Supplemental EIS for the Western Planning Area lease sales ( BOEMRE, 2011; Bureau of Ocean Energy Management [ BOEM ] , 2012 ), which present updated
environmental baseline inform ation relative to the Macondo incident.

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 ra te for 1996 to 1999 was approximately five blowouts per 1,000 well starts, or one blowout per 200 well starts ( MMS, 2000 ). More recently, in its Draft Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEMRE confirmed that “significant change s to the spill rates for the entire OCS are not anticipated” (BOEMRE, 2011).

Historically, most blowouts have not resulted in oil spills . O f 151 well blowouts in the Gulf of Mexico from 1971 to 1995, only 18 (12%) resulted in oil spills , with a to tal com bined volume of 1,000 barrels ( bbl ) of crude oil and condensate released (MMS, 200 0 ). Between 1964 and 1999, almost all offshore spills (94%) from drilling and production

- related operations on the OCS were less than or equal to 1 bbl in size (Anderson and LaBelle, 2000) . According to BOEMRE’s Interim
Final Drilling Safety Rule ( 75 Federal Register (FR) 63365 dated 10 October 2010 ) issued following the Macondo incident , the baseline risk of a catastrophic blowout is estimated to be about once every 26 year s

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 2 All the proposed activities and facilities disused in this EP are covered by the Regional Oil Spill Response Plan (OSRP) approved on 24 August 2012 for Anadarko Petroleum Corporation 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 respon se to spill s ranging from small operational spills

to a worst case dis charge (WCD) from a well blowout. Anadarko’s spill response program meets the response planning requirements of the relevant coastal states and applicable F ederal oil spill planning regulations and also includes information regarding Anadarko’s regional o il spill organization and dedicated response assets, potential spill risks, and local environmental
sensitivities. The OSRP descri bes personnel and equipment mobilization, the incident management team organization, and an overview of actions and notificat ions to be taken in the event of a spill.

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

NTL 2008

- G04. The main impact

- related discussions are in Section A (Impact

- Producing Factors)
and Section C (Impact Anal ysis). Table 1 lists and summarizes the NTLs applicable to this EIA.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 3

Figure 1. Location of Green Canyon Blocks 683 and 727.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 4 Table 1. Notices to Lessees and Operators (NTLs) referenced in this Environmental Impact Analysis ( EIA )

.

NTL Title Summary

2012

- BSEE

- G01 Marine Trash and Debris

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

2012

- JOINT

- G01 Vessel Strike Avoidance and Injured/Dead Protected Species Reporting Recommends protected species identification guides be
carried on all G ulf 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 Outer Continental Shelf ( OCS ) Blocks Requiring Archeological Resources Surveys and Reports Provides new information of which OCS blocks require archeological surveys and reports and required line spacing in
each block. This NTL augments NTL 20 05

- G07.

2010

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

Resources Informs operators using subsea blowout preventers (BOPs) or surface BOPs on floating fa cilities 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 regul ations (75 FR 63346). Informs operators that BOEMRE will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond to a
blowout or other loss of well control.

2010

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

OCS Rescinds the limitations set forth in NTL 2008

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

2009

- G40 Deepwater Benthic Communities Guidance for avoiding and protecting high

- density deepwater
benthi c 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
reli ef 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

co ntrol of electromagnetic emissions and use of boats and aircraft in the applicable warning area or water test area before commencing such traffic.Table 1. (Continued).

Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 5 NTL Title Summary

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 Report s 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, Regu lation and Enforcement; BSEE = Bureau of Safety and
Environmental Enforcement.



## A. Impac t

- Producing Factors

Table 2 is a matrix of impact

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

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

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

. Potential IPFs for the proposed activity are listed belo w 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)

T wo 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 and their own propellers and thrusters to maintain pos ition. Essentially, through satellite navigation

, the location of the vessel is precisely monitored and thrusters positioned at various locations about the vessel’s hull are activated to provide any required stationkeeping adjustment. This allows operati ons at sea where mooring or anchoring is not feasible.

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

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

, as discussed in Section C.5.1

.
Drilling operations produce noise that includes strong tonal components at low frequencies, and

in some cases infrasonic frequencies (MMS, 2000). Drilling noise from drillships and semisubmersibles is not particularly inten se 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 ligh ting for navigational and aviation safety in accordance with applicable Federal safety regulations.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis 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)

-- X (4)

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

-- -- (1)

-- -- ( 1)

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

-- -- (2)

-- -- (2)

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

-- -- (3)

- - -- (3)

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

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

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

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

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

- endangered marine mammals (protected) X

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

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

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

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

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

-- X (6) Fisheries Resources Pelagic communities and ichthyoplankton X

-- -- X X

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

-- -- X X

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

-- -- (7)

-- -- -- -- -- -- -- X (6) Prehistoric archaeological sites

-- -- (7)

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

Beaches

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

-- X (6) Wetlands and seagrass beds

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

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

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

-- X (6) Socioeconomic and Other Resources

Recreational and commercial fishing X

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

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

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

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

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

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

WCD = worst case discharge.Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 7 Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any anchors will be on the seafloor within the following: (a) 4

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

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

- m , 1

- mi, or 3

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

- activity zone; or (d) Pro ximity 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 featur e, or

no

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

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

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

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

- Relief) Stipulation attached to an OCS lease.

• The Live Bottom (Low

- Relief) Stipulation i s not applicable to the lease area.

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

• No impacts on high

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

- density che mosynthetic communities or coral communities within 610 m ( 2,000 ft) of any drilling mud/cuttings discharge location.

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

• Previously drilled wells i n the GC 683 and 727 area did not indicate the presence of H 2 S and BOEMRE has
classified the area as “ H 2 S absent” in accordance with 30 CFR 250. 490(c )

. (6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fu el 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 th e resources marked (X) in the matrix, and impacts are analyzed in Section C

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

- probability for the occurrence of sh ipwrecks 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 th at no impact would occur, the EIA can note that in a sentence or two.

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

- probability blocks for shipwrecks and is well beyond the 60

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

(8) All activities that you determine might have an adv erse effect on endangered or threatened marine mammals
or sea turtles or their critical ha bitats.

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

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

• Not applicable.Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 8 

## A.2 Physical Disturbance to the Seafloor

In water depths of 600 m (1,969 ft) or greater, DP drillships and DP semisubmersibles disturb only a very small area of the seafloor around the wellbore (SHL) where the bottom template and blowout preventer are located. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac) (MMS, 2007 a )

.



## 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 (SO
x ), nitrogen oxides (NO
x ), volatile organ ic compounds (VOCs), and carbon monoxide (CO).

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



## A.4 Effluent Discharges

Effluent discharges are summarized in EP Section F

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

. Any d ischarges 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 allo ws thei r return to the surface is set. Excess cement slurry will also be released at the seafloor during casing installation for the riserless port ion of the drilling operations. S ynthetic

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

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

non

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, unco ntaminated fresh water and sea water, and ballast water.



## A.5 Water Intake

Seawater will be drawn from th e ocean for once

- through, non

- contact cooling of machinery on the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the bes t technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organisms. The current NPDES General P ermit No. GMG 290000 doesGreen Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 9 not specify requirements for existing facilities (those that started construction b efore

16 July 2006)

. The DP drilling vessel ultimately selected for this project will be in compliance with all cooling water intake structure (CWIS) 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 150 bbl over the life of this project.
Th e 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 Internation al Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements and USEPA and U.S. Coast Guard ( USCG ) regulations, as well as those of the BOEMRE

. For example, BOEMRE regulations at 30 CFR 250.300(a) and (b)(6) prohibit operat ors 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 precaution s such as covering outside trash bins to prevent accidental loss of solid waste. In addition to the regulations in 30 CFR 250 , MMS issued NTL 2007

- G03

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



## A.8 Support Vessel and Helicopter Traffic

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

N o terminal expansion or construction is planned at either location

.

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

- trip s per week

, and the supply vessel will make two round

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

A helicopter will make one round

- trip daily between the drilling rig and the heliport

. The helicopter will be used to transport personnel and small supplies and will normally take the
most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 m (700 ft) while in transit offshore, 305 m (1,000 ft) over unpopulated areas or across coastlines, and

610 m (2,000 ft) over popul ated areas and sensitive habitats such as wildlife refuges and park properties.Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 10 

## 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

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

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

.

MMS ( 2007b)

, BOEMRE (2011)

, and BOEM (2012) analyze d 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 analys e s in MMS (2007b ) and BOEM (201 2 ), 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 h ave been < 1 bbl, and this size is predicted to be the most c ommon in ongoing and
future OCS activities in the Western and Central Gulf of Mexico Planning Areas . As the spill size increases, the incident rate declines dramatically (MMS, 2007b ; BOEM, 201 2 ). The average size for spills < 1 bbl is 0.07 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl (MMS, 2007b). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

The water

- soluble fractions of diesel are dominated by two

- and three

- ringed polycyclic aromatic hydrocarbons (PAH s ), 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 aerob ic microbial oxidation. Diesel is so light that it will not sink to the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally

occurs only in coastal areas with high suspended solids loads (National Research Council, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes ( National Oceanic and Atmospheric Administration [ NOAA ] , 20 06). . 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, g iven the open ocean location of the lease area and response actions, it is expected
that impacts from a small spill would be minimal (BOEM, 201 2 )

.

For purposes of this EIA, t he fate of a small diesel fuel spill was estimated using NOAA’s ADIOS2 (Automated Data Inquiry for Oil Spills) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and di spersion over time, as well as changes in the density, viscosity, and water content of the product spilled. I t is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea
surface with diesel fu el 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.Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 11 The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill,
indicate that a small fuel spill would not have any impacts on coastal or shoreline resources.
The lease area is 120 miles ( 194 km) from the nearest shoreline. Modeling results discussed below indicate that a spill in the lease area w ould have a 4 % or less probability of reaching the

c oastal areas of Louisiana within 10 days after a spill

. By that time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, without taking into

account Anadarko ’s response measures. MMS (2007b) similarly concluded that spills <1,000 bbl are not expected to persist as a slick on the surface of the water beyond a few days and are unlikely to make landfall or reach coastal waters prior to breaking up. MMS (2007b) noted that this conclusion is supported by a previous analysis of 3

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

Spill Response



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

- term environmental consequences.

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

Spill Size

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a . In accordance with requirements of NTL 2010

- N06, Anadarko has estimated a WCD
for this EP as 340,281 barrels of oil per day (BOPD). The estimated time to drill a relief well is
between 132 and 146 days from the time of a blowout un til the relief well is completed. T he total volume of a spill over this duration (146 days) would be 49,681,026 barrels of oil

. The detailed analysis of this calculation can be found in EP Section H

.

deep drilling

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

NTL 2010

- N0 6, 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

- N 10 and the Interim Final Drilling Safety Rule, which specif ies
additional safety measures for OCS activities. blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per ex ploratory well for non

- North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEMRE is in the process of updating these spill frequency estimates to include the recent Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated ( BOEMRE, 2011; BOEM, 2012 ). As noted in the Introduction , the baseline risk of a catastrophic blowout is estimated to be once every 26 years (BOEMRE Interim Final Drilling Safety Rule, 75 FR 63365,

10 October 2010).

Spill Trajectory

. The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a

compu ter 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 estim ating the fate of small fuel spills.
The primary criticism of the OSRA model results as provided in Ji et al. (2004) was that theGreen Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 12 model did not evaluate the fate of a spill over time periods longer than 30 days, nor d id it predict the fate of a release th at continues over a period of weeks or months, as in the Macondo ( Deepwater Horizon ) incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size but has generally been used by the BOEMRE /MMS to evaluate contact probabilities for spills greater than 1,000 bbl.

To address this criticism

, a specia l OSRA run was conducted for the recent BOEMRE Central and
Western Gulf of Mexico Planning Area Supplemental EIS s ( BOEMRE

, 2011; BOEM, 2012 ) 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 traject ory tracked for up to 120 days.

The OSRA model run for this revised ana lysis was conducted for five hypothetical launch points
in the Central a nd Western Gulf o f Mexico Planning Areas

. These launch point s were deliberately located in area s identified as having a high possibility of containing large oil

reserves.

The five la unch point areas were as follows:

1. Central Gulf of Mexico shelf are a 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. We stern Gulf of Mexico slope area ( 27.51367 ° N latitude, 94.51836 ° W longitude).

The resul ts 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 an d 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 pr operties of the oil, influencing potential effects to marine organisms and ecosystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water

- in

- oil emulsions, photochemica l oxidation, microbial degradation, adsorption to suspended particulate matter, and stranding on shore or sedimentation to the seafloor (National Research Council, 2003).Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 13 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 d ays (Modified from: BOEM, 201 2 , Appendix C).

Season Winter Spring Summer Fall

Day 3 10 30 120 3 10 30 120 3 10 30 120 3 10 30 120

Cou nty 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

-- -- -- --

“

- - ” = V alues < 1.0 % . A reas 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

. BO EMRE has issued re c ent NTLs following the Macondo spill that clarify
additional oil

- spill prevention and response planning requirements. These NTL s are summarized

in Table 2

, and additional BOEMRE (2011 ) guidance is provided below.

NTL 2010

- N10

– Stateme nt 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 atGreen Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 14 75 FR 63346. The NTL also informs lessees that BOEMRE will evaluat e whether the operator has s ubmitted 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 inte nds 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 Developm ent Operations Coordination Documents on the OCS

Anadarko submitted an updated Gulf of Mexico Regional OSRP to BOEMRE on 21 July 2011

. In addition, Anadarko submitted a Regional OSRP Certification Letter per 30 CFR 254.2(b) to

BOEMRE on 21 July 2011. The OSRP provides a detailed plan for Anadarko to respond to and rapidly and effectively manage oil spills that may result from dri lling 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, DPPs, or DOCDs. The required supplemental inform ation includes the following: 1) a description of the blowout scenario as required by 30 CFR 250.213(g) and 250.243(h); 2) a description of their assumptions and calculations used in determining the volume of the worst

- case discharge required by 30 CFR 250 .219(a)(2)(iv) (for EPs) or 30 CFR 250.250(a)(2)(iv) (for DPPs and DOCDs); and 3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early

interven tion in the event of a blowout, including the arrangements for drilling relief wells and any other measures proposed. The early intervention methods of the third requirement could actually include the surface and subsea containment resources that

BOEMRE a nnounced in NTL 2010

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

• responsibilities of all Anadarko and contract personnel to report any observed discharge from known or unknown sources;

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

• c ontact 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. T hese vessels have o leophilic brush pack skimming systems operating in troug hs built
into the hulls below deck storage and marine electronics packages including marine, aircraft and

company

- frequency radios, radar, moving map plotters

, GPS, satellite phone s , 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 controlGreen Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 15 room overlooking the skimmer deck. The estimated daily recovery capacity for the HOS S barge is app roximately 43,000 bbl

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

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

Anadarko also has a contract with National Response Corporation (NRC) for additional spill response equipment. NR C has a dedicated fleet for the Gulf of Mexico and has additional available equipment staged throughout the U

. S. NRC o il s pill r esponse vessels includ e the Admiral, Energy

, and Liberty ; their o il s pill r esponse b arges Defender and Valiant are equipped with spill containment and recovery gear to respond on request.

NRC's s upplemental o ffshore s kimming s ystems are stored on trailers as units consisting of skimmers, boom, and hydraulic power sources in various locations. Units can be mobilized to a staging area and loaded onto a supplemental offshore vessel. Vessels of Opportunity will be needed for deployment.

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

- psi single ram capping stack and dispersant injection capability. MWCC can also install and operate the interim containment system, including subsea flowlines, manifold, and risers. The interim system is engineered to be used in depths up to 3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day (BLPD) (and 120 million standard cubic feet per day [MMSCFD] of gas) with potential for expansion.

In addition, Anadarko is a member of the Helix Well Containment Group (HW CG), a part of the
Helix Fast Response System (HFRS)

, and has available all the common response equipment and

services of the HWCG group

. Anadarko’s membership allows access to subs ea well contain ment and well shut

- in equipment including the Q4000 and Helix Producer I vessels to facilitate control and containment of spills. At full production capacity, the HFRS can handle up to approximately 55,000 BOPD ; 70,000 BLPD ; and 95 MMSCFD o f gas at 10,000 psi in water depths to 2,438 m ( 8,000 f t). HWCG also can provide a 10,000

- or 15,000

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

.

See EP Section H f or 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 i ncorporated by reference into this document. These accidents are discussed briefly below along with a hydrogen sulfide ( H 2 S ) release . T here are no other site

- specific issues raised for the drilling of
the well 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 q uantity 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,Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 16 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, 2011; BOEM, 2012 )

.

Ris er Disconnect SBM Spills

. In deepwater drilling, SBMs a re preferred over petroleum oil

- based muds (OBMs) due to the superior environmental properties of SBMs

. The synthetic base fluid used in SBMs are less toxic to the marine environment and have the pot ential to biodegrade.
SBMs have been used in the Gulf of Mexico since the mid

- 1990’s , and between 5 and 20 SBM releases are anticipated each year as a result of offshore drilling programs. The majority of these releases are <50 bbl in size, but accidenta l riser disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,381 bbl) quantities of dril ling fluids. Riser disconnect accidents are of particular concern when SBM s are in use ( BOEM , 201 2 ).

Vessel Collisions

. BOEMRE data show th at 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

, f ires 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 M ain Pass leas e 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
collision s

. Human error account ed for ap proximately half of all reported vessel collisions from

2006 to 2009. As summarized in MMS (2007b ) and BOEMRE (2011 ), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of
diesel fuel or chemicals. Anadarko will comply with all USCG

- and BOEMRE

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

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release of gas , condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, while blowouts are considered to be a subset of more serious incidents with greater risk of oi l 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.

M easures to prevent a blowout

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

NTL 2010

- 06

. The potential for a loss

- of

- well

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

NTL 2010

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

H 2 S Release

. Pursuant to 30 CFR 250.4 90 (c), Anadarko is requesting in the EP that the BOEMRE Regional Supervisor, Fie ld Operations, classify the area in the proposed drilling operations as an
area where H 2 S is absent. Based on this, no further discussion of H 2 S is warranted.Green Canyon Blocks 683 and 727 S eptember 2012 Environmental Impact Analysis Page 17 

## B. Affected Environment

The lease area is in the central Gulf of Mexico, 120 miles ( 194 km) from the nearest shoreline,
and 131 miles ( 211 km) from the onshore support base at Port Fourchon, Louisiana ( Figure 1 ).

Based on the g eohazard s urvey conducted by Geoscience Earth & Marine Services, Inc. ( GEMS, 2003) and s ite c learance letter (GEMS, 2011)

, w ater depth at the wellsite is 1,367 m (4,484 ft) ( Figure 2 ). T here is no evidence of significant seafloor or subsurface faulting, fluid expulsion features, or high

- density deepwater benthic communities near the wellsite ( GEMS , 2011)

.

A detailed description of the regional affected environment, including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic
conditi ons, and other marine uses i s provided in recent lease sale EISs (MMS, 2007b, 2008). These regional descriptions remain valid and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource, including site

- specific and/or new information if available

, are presented in Section C

.
The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the
oil slick on the sea surface, plumes of submer ged oil droplets were produced when subsea dispersants we re applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c)

. Despite limited information on the water quality of deep water, it is clear
that condition s in the offshore waters of the Gulf of Mexico w ere 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 offshor e water quality ( BOEMRE, 2011; BOEM, 2012 ).

The lease area is located approximately 178 miles ( 287 km) southwest of the Macondo spill site. Based on an analysis of satellite imagery (ESRI, 2010), the surface slick did not extend over the
lease area and there is no indication that water quality in the lease area was affected. P rior to
the Macondo incident, water quality in deep, offshore waters of the Gulf of Mexico wa s expected to be good

, with low levels of contaminants (Kennicutt, 2000)

. Based o n the information currently available, there is no reason to expect any change in water quality
conditions in the lease area from those predicted in the recent lease s ale EISs (MMS, 2007b,
2008; BOEMRE, 2011; BOEM, 2012 )

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 18

Figure 2. Bathymetric map of the lease area showing the surface hole location (SHL) and bottom hole location (BHL) of GC 727 Well “F”

. (Water depths shown in meters.)Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 19 

## C. Impact Analysis

This section analy z es the potential direct and indirect impacts of routine activities and accidents. Impacts have been analyzed extensivel y in recent lease sale EISs for the Central and Western
Gulf of Mexico Planning Areas (MMS, 2007b

, 2008 ; BOEMRE

, 2011; BOEM, 2012 ) as well as the environmental assessment for Gulf of Mexico deepwater operations and activities (MMS, 2000). The information in these documents is incorporated by reference. Potential s ite

- specific issues
are addressed in this section.



## C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site

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

. Because of the distance from shore

- based pollution sources and the lack of sources offshore

, air quality at the wellsite is expected to be good. The attainment status of Federal OCS waters is unclassified because there is no provis ion 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 r outine air pollutant emissions,

a small fuel spill , and a large oil spill (WCD).

BOEMRE has reexamined the analysis for air quality presented in MMS (2007b, 2008) based on
additional information and in consideration of the Macondo oil spill event

. No subs tantial new
information was found that would alter the potential impact s on air quality presented in previous lease sale EIS s ( BOEMRE

, 2011; BOEM, 2012 ).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect a ir 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

- pow ered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO
x , VOCs,
and CO. Emissions of pollutants into the atmosphere from these activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. As the BOEMRE found in the
lease sale EISs, the incremental contribution of activities similar to Anadarko’s proposed activities to the cumulative impacts is not significant and will not cause or contribute to a violation of any N ational A mbient A ir Q uality S tandard (NAAQS) (MMS, 2007b

, 2008). Since the BOEMRE completed the lease sale EISs, the USEPA has adopted a new short

- term NAAQS for nitrogen dioxide. The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore, emissions
from the act ivities described in Anadarko’s propose d EP are not likely to contribute to violations of any NAAQS onshore.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 20 Carbon dioxide (CO 2 ) and methane ( CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions fro m all OCS activities. According to the Programmatic EIS (MMS, 2007a), estimated CO 2 emissions from all OCS activities in the

2007

- 2012 leasing program are about 0.08% to 0.016% of the global CO 2 emissions from fossil fuel combustion. Greenhouse gas emiss ions 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 pro ject represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the lease sale EIS (MMS

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

Due to the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MMS, 2 007b)

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

. The Air Quality Emissions Report (see EP Section G ) prepared in accordance with BOEMRE requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303

, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required

.
The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), i s designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air quality area. The BOEMRE is required to notify the National Park Service (NPS) and U.S. Fish and Wildlife Service ( USFWS ) if emissions from proposed projec ts may affect the Breton Class I area. Additional review and mitigation measures may be required for sources within 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 178 mi les ( 287 km) from the Breton
Wilderness Area

, so air quality impacts on the Wilderness Area are not expected. Anadarko will comply with all BOEMRE requirements regarding air emissions.



### Impacts of a Small Fuel Spill

Po tential impacts o f a small spill on air quality are expected to be consistent with th os e analyzed
and discussed in EISs prepared for recent lease sales (MMS, 2007b, 2008 ; BOEMRE, 2011; BOEM, 2012 ). The probability of a small spill would be minimized by An adarko ’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 VO Cs 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 21 A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

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

2012 ).

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

measures. Realtime wind and current data fro m 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 ge nerate a plume of black smoke and result in emissions of NO x , SO
x , CO, and PM, as well as greenhouse gases. However, in situ burning would occur only after authorization
from the USEPA.

Due to the lease area location ( 120 miles [ 194 km]) from the nearest shoreline, most air quality impacts would occur in offshore waters with minimal chance to affect onshore air quality.



### C.1.2 Water Quality

There are no site

- specific water quality data for the lease area. Due to the lease location in deep, off shore 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 oxy gen. 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 sedi ments and up through the water column.

The lease area is located approximately 178 miles ( 287 km) f r om the Macondo spill site

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

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

a small fuel spill and a large oil spill (WCD).



### Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and several
kilometers down c urrent 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. A ll 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 ).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 22 Treated sanitary and domestic wastes , i ncluding 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, l ittle

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 r ig 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 requir ements. Based on adherence to permit limits and applicable regulations, l ittle or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, 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 wate r quality are expected to be consistent with th os e analyzed and discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011; BOEM, 2012 ). 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
Anad arko ’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 e xtent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, i t is estimated that over 90% 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 PAH s , which are moderately volatile (National Research Council, 2003). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel is so light that it is not possible fo r the oil to sink and pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solid loads (National Research Council, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

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

to make landfall or reach coastal waters due to both response efforts that would be undertaken
as well as natural attenuation (see Section A.9.2 ).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 23 

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

Potential impacts of a large oil spill on wate r quality are expected to be consistent with th os e analyzed and discussed in recent lease sale EISs (MMS, 2007b, 2008). A large spill w ould affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum 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 (Camil li et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval from the USEPA. Small droplets in the water may adhere

to suspended sediment s and be removed from the water column (Operation al Scientific Advisory Team [ OSAT ], 2010).

Due to the lease area location ( 120 miles or 194 km from the nearest shoreline)

, it is expected
that most water quality impacts would occur in offshore waters , especially in the event of a spill lasting less than 30 days ( Table 3 ).



## C.2 Seafloor Habitats and Biota

W ater depth at the proposed B HL is 1, 367 m ( 4,484 ft) . The seafloor generally dips toward the

west

- southwest at about 0.7° at the proposed wellsite GC 727 Well "F"

. The seafloor in this area is irregula r as a result of the numerous fault scarps and the deformation of the shallow
overburden and t he near

- surface sediments are expected to be normally consolidated clays forming a drape over the area. The immediate regions around the proposed well location h ave no evidence of seafloor instability within 610 m (2,000 ft) of the wellsite. No areas of possible hard bottom or microseepages were seen within 610 m (2,000 ft) of the wellsite ( GEMS

, 201 1 )

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

- scan sonar during the s ite

c learance s urvey, the seafloor is expected to consist mainly of soft bottom communities. The Site Clearance Survey did not identify any features that could support high

- density deepwater
benthic communities within 610 m (2,000 ft) of the wellsite. No areas of gaseous sediments or possible hydrocarbon seepage were defined in the study area, and the presence of chemosynthetic communities is considered low ( GEMS , 201 1 ).



### C.2.1 Soft Bottom Benthic Communities

There are no site

- spe cific 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.

T able 4 summarizes data collected at four stations. The closest stations B1 and GKF were
located 37 and 43 miles (60 and 69 km), respectively, from the lease area. These two stations were in greater water depths (2,256 and 2,460 m [7,402 and 8,071 ft]) th an the lease area. Station C4 was located at a greater distance from the lease area (64 miles [103 km]) but in a water depth (1,446 m [4,744 ft]) similar to that of the lease area. Station MT4, located

107 miles (172 km) from the lease area, was in a wat er depth of 1,403 m (4,603 ft), similar to that of the lease area and is included for comparison. Sediments at the stations closest to the lease area (B1 and GKF) were predominantly clay ( 52.7 % to 59.1 %) , with 37.4% to 44.5% silt.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 24 Table 4

. Benthic communi ty 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 f rom: Wei, 2006 ; Rowe and Kennicutt, 2009).

Station Distance to
Lease Area

(miles) Water Depth (m) Abundance

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

B1 37 2,256 157,417 1,446 252

GKF 43 2,460 84,348 737

-- C4 64 1,446 273,585 3,045 743

MT4 107 1,403 246,058 3,262 1,548

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

Wei (2006).

Densities of meiofauna ( animals passing through a 0.5

- mm sieve but retained on a 0.062

- mm sieve) in water depths representative of the lease area ( 1, 367 m [ 4,484 ft]) typically range from approximately 246,000 to 273,000 individuals/m 2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant meiofauna l 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 decreas e 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/m 2 , or greater than the numbers for the closest locations
listed in Ta ble 4

.
Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of

Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth

- dependent faunal zones (1 through 4), two of w hich are divided
ho r izontally. The lease area is in Zone 3 W. This zone, with stations in water depths of 1,875 to 3,008 m ( 6,152 to 9,869 ft)

, had the polychaetes Levinsenia uncinata

, Paraonella
monilaris

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

Megafaunal densities from nearby S tation B1 was 252 individuals/ha ( Table 4 ). Densities of

200 to 1,600 individuals/ha were reported from other stations located at a depth range similar

to that of the lease area. Common megafauna included motile groups such as decapods, ophiuroids, ho lothurians, and demersal fishes, as well as sessile groups such as sponges and

anemones.

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

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

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

IPFs potentially affecting benthic communities are physical disturba nce to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowoutGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 25 at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.

Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships or semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and blowout preventer are locat ed. Depending upon the specific well configuration, this area is generally about 0.25 ha (0.62 ac).

T he areal extent of these impacts from the DP rig will be small compared to the lease area itself, and these type s oft 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 communi ties 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, dr illing 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 th e 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 S helf 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 e nrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic f luid is decomposed by microbes, the area will gradually return to pre

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

T he areal extent of impacts from drilling discharges will be sm all. 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 (Ga llaway, 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 26 

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

The most likely effec ts of a subsea blowout on benthic communities would be within a few
hundred meters of the wellsite. The MMS (2007b) estimat ed 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 t he project area are assumed to largely be silt and clay ( Rowe and Kennicutt, 2009 ).

Recent lease sale EISs (MMS, 2007a, 2008) i n dicat ed 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 subsurf ace 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 f eatures or areas that could support high

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

- density deepwater corals and other associated high

- density hard bottom

communities. C hemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald, 2002). Deepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007;

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities.

The nearest known chemosynthetic community site is located approx imately 26 miles (41 km)
north of the lease area in GC 994 . The nearest identified deepwater coral community is located

in GC 600, approximately 16 miles ( 26 km) east

- northeast of the lease area.

No mounds, depressions, or hard bottom features occur within a 2,000

- ft radius around the proposed wellsite. Therefore, the potential for high

- density chemosynthetic communities within 2,000 ft of the proposed location is low ( GEMS , 2011 ).

IPFs potentially affecting high

- density deepwater benthic communities include physical disturbance of the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 27 

### Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease area, DP drillships or semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and blowout preventer are located. Depending upon the specific well co nfiguration, this area is generally about 0.25 ha (0.62 ac).

T he areal extent of these impacts from the DP rig will be small , and NTL 2009

- G40 requires that high

- density deepwater benthic communities and f eatures o r areas that could support high

- density chemosynthetic communities, or deepwater corals communities be avoided

. Based on the GEMS (2011) report, there will be no i mpacts on chemosynthetic or deepwater coral

communities from this project.



### Impacts of Effluent Discharges

The s ite c learance s urvey (GEMS, 2011) did not identify any features that could support high

- density deepwater benthic communities within 610 m (2,000 ft) of the proposed drilling locations, and the presence of chemosynthetic communities in the lease area is considered

remote. Mo nitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 500 m (1,640 ft ) of the
wellsite , although detectable deposits may extend beyond this distance (Conti nental 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. A lthough 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 subsu rface 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 deepwat er 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 u se of dispersants , and such approval would be obtained from the USEPA prior to the use of dispersants

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

source . I ncubation experiments with environmental isolates demonstrated faster than 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 28 Potential impacts of oil on high

- density deepwater benthic communiti es 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 re quire 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 b y 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 ef fects 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 (Octobe r 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 observe d 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 substance. Out of 40 large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had a colony of stony corals similarly affected and partially covered with a similar brown substance. Until laboratory analyses are conducted, scientists cannot be certain what caused the impacts. Sediment and coral samples were collected with a remotely operated vehicle and brought to the surface for analyses. Further testing will also determine if the substance is oil, and if so,
whether it is consistent with the release from the Macondo spill.



### C.2.3 Designated Topographic Features

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

- activity zone as
identified in NTL 2009

- G39. The nearest designated topographic feature is Ship Shoal South in Ewing Bank (EW) Block 947, 112 miles ( 181 km) north of the lease area

.
There are no IPFs associated with either routine operations or accidents that could cause impacts to designated topographic features due to the distance from the le ase 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 c ontinental 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, 194 miles ( 313 km) northeast
from t he lease area

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 29 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 reac h 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 t he Live Bottom (Low

- Relief) Stipulation, which applies to

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

- G39, is

Destin Dome Block 573

, approximately 234 miles ( 377 km) northeast of the lease area.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these featu res 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 Threate ned, 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
und er the Marine Mammal Protection Act ( MMPA )

.
Endangered or threatened species that may occur in the project area and/or along the northern
Gulf C oast are listed in Table 5 . The table also indicates the location of critical habitat (if designated in the Gul f 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 jurisdictio n for ESA

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

ESA

- listed birds and the West Indian m anatee.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 30 Table 5

. Federally

- listed endangered and threatened species potentially occurring in the lease
area and along the northern Gulf C oast.

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

Marine Mammals

Sperm whale Physeter macrocephalus E X

-- None West Indian manatee Trichechus manatus latirostris E

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

-- None Fin whale Balaenoptera physalus E X a

-- None Humpback whale Megaptera novaeangliae E X a

-- None North Atlantic right whale Eubalaena glacialis E X a

-- None Sei whale Balaenoptera borealis E X a

-- None Sea Turtles

Loggerhead turtle Caretta caretta T X X None Green turtle Chelonia mydas T, E b X X None Leatherback turtle Dermochelys coriacea E X X None Hawksbill turtle 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 (A labama, Choctawhatchee, Perdido Key, St. Andrew) Peromyscus polionotus E

-- X Alabama and Florida (Panhandle) beaches

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

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

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

As manda ted 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 B iological A ssessment 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. T he informal ESA consultation with USFWS was concluded with a
letter dated 14 September 2007. The USFWS concurred with MMS’s determination that proposed actions of the current Five

- Year Leasing Plan were not likely to adversely affect threatened/endangered species or designated critical habitat under USFWS jurisdiction. Following the Macondo spill

, BOEMRE requested to reinitiat e an ESA consultation with bothGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 31 NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on

24 September 2010 , a nd t he USFWS responded with a letter to BOEMRE on 27 September 2010. At present, the NMFS and US FWS have placed th e consultation process on hold because they
feel the environmental baseline information needs to be updated for the post

- Macondo spill

enviro nment based on the results of the Natural Resource Damage Assessment ( NRDA ) process. The NRDA data have yet to be released , and the existing consultation remain s in effect (BOEMRE, 2011)

. The existing consultation recognizes that BOEMRE

- required mitigations and other reasonable and prudent measures should reduce the likelihood of impacts from all

BOEMRE

- authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include
the Wes t Indian manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of
beach m ouse . 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 . T hese 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 righ t 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 s perm whales occur within the
Gulf of Mexico. A species description is presented in a recent lease sal e EIS (MMS, 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a “strategic stock” (defined as a stock that may have unsustainable human

- caused impacts) by NOAA Fisheries (Waring

et al., 2009). No critical habitat for the spe rm 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

- fun ded Sperm Whale Seismic Study (SWSS) consisted of mixed

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

- tracked individuals suggest that this area of the Gulf continental slope isGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 32 within the home range of the Gulf of Mexico population (within the 95% utilization distribution) (Jochens et a l., 2008).

IPFs potentially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents

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

- G03 will minimize the potential
for marine debris

- related impacts on sperm whales

.

C urrent threats to sperm whale populations worldwide are discussed in a final recovery plan for the sperm whale r ecently published by NOAA (NMFS, 2010 a ). Threats are defined as “any factor that could represent an impedimen t 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 pre y base due to climate change and ecosystem change, and cable laying. In
the Gulf of Mexico , the impacts from many of these threats are identified as either low or
unknown ( BOEMRE, 2011; BOEM, 2012 )

.


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

Nois e 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 intens ity 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 d rilling 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 ar e not identified as IPF s for sperm whales in recent lease sale EISs (MMS, 2007b, 2008) or the NMFS (2007) Biological Opinion.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales

, and there is al so 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 s trikes, the Bureau of Safety and Environmental Enforcement ( BSEE ) and BOEM issued Joint NTL 20 12

- G0 1 , 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 33 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 NT L will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm
whales.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales . With implementation of the mitigation measures in NTL 2007

- G04 , NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential th reat 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 r equirement to maintain a distance of 9 1 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 o f 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 aut hors concluded that the observed reactions to brief overflights by
the aircraft were short

- term and probably of no long

- term biological significance.

W hile flying offshore in the Gulf of Mexico , helicopters maintain altitudes above 213 m (700 ft) during tr ansit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animals. Although responses are possible (Smultea

et al., 2008), the NMFS (2007) concluded that t his altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected

.


### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent lease
sale EISs (MMS, 2007b, 2008) and by NMFS (2007) . Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

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

.
The pro bability 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 spe rm whales. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the

concentra tions of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions atGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 34 the time and the effectiveness of spill response measures. Section A.9.2 discusses th e 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 conta minated prey; and stress from the activities and noise of response vessels and aircraft ( Marine Mammal Commission [ MMC ] , 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mo bility of sperm whales, no significant impacts would be expected.



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

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

. For this EP , there ar e no unique site

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

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

, disruption of social structure

, changing prey availability and foraging distribution and/or
patterns

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

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessel s would operate in accordance with NTL 2012

- G01 to reduce the potential for striking or disturbing these animals.



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

M ost of the manatee population is located in peninsular Florida (USFWS, 2001). Manatee sightings in Lo uisiana 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).

IPF s potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees, as the lease

area is approximately 120 miles ( 194 km) from the nearest shoreline (Louisiana). As explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. Compliance with NTL 2007

- G03 will minimize the potential for marine
debris

- related impacts on ma natees.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 35 

### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). To
red uce the potential for vessel strikes, BSEE and BOEM issued Joint NTL 20 12

- G0 1 , 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 altitude s 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 wildl ife refuges and park properties. This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts are expected.



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

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritation, inflammation, or nec rosis; 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 re sponse vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of
social structure

, changing prey availability and foraging distribution and/or patterns

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

In the event that a large spill reached coastal waters where manatees were present , the level of vessel and aircraft activity associated with spill response could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2012

- G01 to reduce the potential for striking or disturbing these
animals , and therefore no significant impacts are expected

.



### C.3.3 Endangered Mysticete Whales

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

Due to the rare occurrence of these whales in the Gulf of Mexico and the limited sco pe and duration of the project, it is highly unlikely that any endangered mysticete would come intoGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 36 contact with any project activities , either routine operations or accidents

. NMFS did not include any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007)

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

, and those analyses are incorporated by reference. If any of thes e 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 additiona l species of marine mammals that may be found in the Gulf of Mexico

, includ ing 2 species of mysticete whales, dwarf and pygmy sperm whales, 4 species of beaked whales, and 1 4 species
of delphinids . All marine mammals are protected species under the MMPA. The most common

non

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

Mysticete whale s . Two species of non

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

100

- m (328

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

- central portion of the northeastern Gulf. The minke whale ( Balaenoptera

acutorostr ata ) 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 s ea, 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 Mexi co 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 undifferen tiated 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.

D elphinids . 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 ), f alse killer whale ( Pseudorca crassidens )

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

- headed whale ( Peponocephala electra )

, p antropical spotted dolphin ( Stenella attenuata )

, p ygmy killer whale ( Feresa attenuata )

,Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 37 short

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

,
r ough

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

. Any of these species could occur in the lease area. The most

commo n non

- endangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and Clymene dolphin.

IPFs potentially affecting non

- endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents

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

- G03 will minimize the potential for marine debris

- related impacts on marine mammals.



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

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher frequency sounds than the dominant low frequencies produced by OCS drilling activities (Richardson et al., 1995). Noise intensity
associated with dril ling 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 s hort 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 an d rig presence are not identified as IPF s for marine mammals in recent lease sale EISs (MMS, 2007b, 2008).



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals

, and there is also a risk of

vess el 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 Joint

NTL 20 12

- G0 1 , which recommends protected species identification trai ning 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 opera tors 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 par allel 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

ceta ceans are observed near an underway vessel

, when safety permits. Compliance with NTL

2012

- 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 (W ü rsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the pote ntial for disturbing marine mammals

, and no significant impacts are expected ( MMS, 2007b ).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 38 

### Impacts of a Small Fuel Spill

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

, and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For
this EP , there are no unique site

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

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during fuel
transfer . In the unlikely event of a spill, implementation of Anadarko ’s OSRP is expected to
lessen the potential for impacts on marine mammals. EP Section H provides detail on spill

response measures , along with a summary of those measures in this EIA

. Given t he open ocean location of the lease area, the limited duration of a small spill and response efforts, it is expected that any impacts would be brief and minimal

.
A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally
within 24 hours. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of

mari ne mammals, no significant impacts would be expected.



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

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

, 2008)

. For this

EP , there are no unique site

- specific issues

. Impacts of oil spills on m arine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritat ion, 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 a ctivities 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 a nimals from prime habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or patterns

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

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb marine mammals and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accor dance with NTL 2012

- G01 to reduce the potential for striking or disturbing these animals , and therefore no significant impacts are expected

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 39 

### C.3. 5 Sea Turtles (Endangered/Threatened)

F ive species of endangered or threatened sea turtles may be found near the lease area. L eatherback ( Dermochelys coriacea ), Kemp's ridley ( Lepidochelys kempii ), and hawksbill ( Eretmochelys imbricata ) turtles are endangered . The loggerhead turtle ( Caretta c aretta ) is currently a threatened species ; however, in March 2001, NMFS and USFWS proposed to list the Northwest Atlantic Ocean population of loggerhead turtles as endangered (75 FR 12598) . The green turtle ( Chelonia mydas ) is listed as threatened, except for the Florida and Pacific c oast of
Mexico breeding population s , 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 Sec tion 7 consultation under the current 5

- Year Program. As a result of this new information, BOEMRE reinitiated ESA Section 7 consultation on the existing Gulf of Mexico lease
sale EIS with NMFS and the US FWS on 30 July 2010. The NMFS responded with a lett er to
BOEMRE on 24 September 2010 , and the US FWS responded with a letter to BOEMRE on
27 September 2010. However, NMFS and the US FWS 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 remain s in effect (BOEMRE, 2011)

.

BOEM (201 2 ) reexamined the impacts analys e s 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 impact s on sea turtles described in previous EISs . In most foreseeable cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick will result in sublethal impacts (e.g., decreased health, reproductive fitness, and longevity; and increased vulnerability to disease) to sea turtles.

Leatherbacks and loggerheads are the most likely species to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and near shore 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 area s, 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 Fl orida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007 b ) . The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR ;

• Green and leatherback turtles

– Green and leatherback tur tles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 201 1 );

• Kemp’s ridley turtles

– The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas, Mexico (NMFS et al., 2010). Kemp’s ridley turtles typically do not nest anywhere near the project area, although there have been occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles

– Hawksbills typica lly do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents

– a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2007

- G03 will minimize the potential for marine debris

- related impacts on
sea turtles.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 40 

### 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 tempora ry 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 rout ine 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, o r 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 Joint NTL 20 12

- G0 1 , which recommends protected species identification training and that vessel operators and crews maintain a vigila nt 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 pot ential 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 impac ts are expected.



### Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008) and the
NMFS Biological Opinion (NMFS, 2007)

. For this EP , there are no unique site

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

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP is expected to
minimize potential impacts on sea tur tles. 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 andGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 41 persistence of impacts would depend on the meteorological and oceanog raphic 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 surf ace 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 b urns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft. However, due to the limited areal extent and short
duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches, as the
lease area is 120 miles ( 194 km) from the nearest shoreline (Lo uisiana ). 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 o f 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 fo od 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 provide s 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 encoun ter an oil slick

, and any sea turtle in an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface
over time , which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

Spilled oil reaching sea turtle nesting beaches could have e ffects on nesting sea turtles and egg development (NMFS, 2007). An oiled beach could affect nest site selection or res ult 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

- G01 to reduce the potential for striking or disturbing these animals , and therefore no significant impacts are expected

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 42 

### C.3. 6 Piping Plov er (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 inverte brates 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 aff ecting 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 la ndfall or reach coastal waters prior to breaking up (see explanation in
Section A.9.2 )

. 

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

Th e lease area is 121 miles (194 km) from the nearest shoreline s inhabited by Piping Plovers ( Figure 3 ). The revised OSRA results (BOEMRE, 2011) 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 tid e 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 co uld 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 Te xas coast at Aransas NWR and
summers at Wood Buffalo National Park in Canada ; t his population represents the majority of the world’s population of free

- ranging Whooping Cranes and reached a record population of
270 at Aransas NWR in December 2008 (Whooping Crane Eastern Partnership, 2010). A

non

- migrating population has been reintroduced in central Florida, and another reintroduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands compri se the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species

. A species description is presented in a recent lease sale EIS (MMS, 2007b). A large oil spill (WCD) is the only IPF potentially affe cting 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

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 43

Figure 3. Location of selected environmental features in relation to the lease area.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 44 

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

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

3 53 miles ( 568 km) from its critical habitat designated in the Aransas NWR

. T he revised OSRA modeling (BOEMRE, 2011) 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 Wh ooping Crane deaths could occur. In the event of a spill, Anadarko would work with the applicable State and Federal agencies to prevent impacts from a spill

.



### C.3. 8 Gulf Sturgeon (Threatened)

The Gulf sturgeon ( Acipenser oxyrinchus desotoi ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatene d 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) t o Suwannee Sound, Florida (Levy County) (NMFS, 2010 b ) ( Figure 3 )

. A species description is presented in a recent lease sale EIS (MMS, 2007b) and in the rec overy plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995)

.
A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 )

.


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

Potential spill impacts on Gulf sturgeon are discussed in recent lease sale EISs ( MMS, 2007b, 2008) and by NMFS (2007)

. For this EP , there are no unique site

- specific issues with respect to this species.

The lease area is approximately 190 miles ( 30 6 km) from the nearest Gulf sturgeon critical
habitat. The revised OSRA modeling (BOEMRE, 2011) predicts that a spill in the lease area has 1% or less probability of contacting any coastal areas inhab ited by Gulf sturgeon within

30 or 120 days.

In the eve nt 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 45 Based on the life history of this species, subadult and adult Gulf stur geon 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 S malltooth S awfish (Endangered)

Smalltooth sawfish ( Pristis pectinata ) are found in the tropical and subtropical Atlantic Ocean.
In the W estern 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 approximate ly 89,621 ha ( 221,459 ac ) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha ( 619,013 ac ) of coastal
habitat. The two units are located along the southwestern coast of Florida between Charlotte
Harbo r 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 affe ct smalltooth sawfish because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 )

.


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

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in recent lease sale EISs ( MMS, 2007b, 2008) and by the NMFS (2007) in its Biological Opinion. For this EP , there are no unique site

- specific issues with respect to
smalltooth sawfish

.

In the event of oil reaching smalltooth sawfish habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills.



### C.3. 10 Beach Mice (Endangered)

Four subspecies of endangered beach m ouse ( P eromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctaw h atchee, Perdido Key, and St. Andrew beach mice. Critical habitat has been designated for all four subspecies ; Figure 3 shows the critic al 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 activitie s 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 l andfall or reach coastal waters prior to breaking up (see Section A.9.2 )

.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 46 

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

Potential spill impacts on beach mice are discussed in recent lease sale EISs (MMS, 2007b, 2008). For this EP , there are no unique site

- specific i ssues with respect to these species that were not analyzed in these documents

.

The lease area is about 263 miles ( 423 km ) southwest from the nearest beach mouse critical
habitat . The revised OSRA modeling summarized in Section A.9.3 predicts that a spill in the
lease area has a 1 % or less probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct
and indire ct 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 tox icity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.



### C.3.11 Elkhorn Coral (Endangered)

Elkhorn coral ( Acropora palmata ) is found primarily in shallow waters with temperatures ranging
between 26 °C and 30 °C (79 and 86 °F) and significant water movement. Elkhorn coral was

once one of the most abundant 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

, e lkhorn 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 wi th routine project activities that could affect this species in the
northern Gulf

. A small fuel spill would not affect elkhorn coral colonies because the oil would float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap re gion of the Flower Garden Banks because of the water depth of the area. A lthough subsurface plumes were reported following the Macondo spill, these plumes resulted from the use of subsea dispersant s at the seafloor.



## C.4 Coastal and Marine Birds

C.4.1 Ma rine 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, exc ept during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shorebird s may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the proj ect area due to the distance from shore. For a discussion of shorebird s and coastal nesting birds, see Section C.4.2

.
Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that tern s, storm

- petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, f our ecologicalGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 47 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 R ibic, 2000).

Common seabird species include Wilson’s S torm

- P etrel ( Oceanites oceanicus ) , Magnificent Frigatebird ( Fregata magnificens ), Northern Gannet ( Morus bassanus ), Masked Booby ( Sula dactylatra ), Brown Booby ( Sula leucogaster ), Cory’s Shearwater ( Calonectris diomedea ), Greater Shearwater ( Puffinus gravis ), and Audubon’s Shearwater ( Puffinus lherminieri ). Seabirds
are distributed Gulf

- wide and are not specifically associated with the lease area.

Relationships with hydrographic features were found f or 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/km 2

.

Trans

- Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and rigs for resting, feeding, or as temporar y 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 drillin g 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 smal l area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2007

- G03 will minimize the potential for marine
debris

- related impacts on birds.



### Impacts of Drilling Rig Presence, Noise, and Light s

Birds that frequent rig s may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Birds migrating over water have been known to strike offshore structures, resulti ng in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and other land

- based structures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be similar. In some cases, migrants sim ply 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 migran ts 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 migran t 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; a pparently 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 effe ct radius of up to 3 miles (5 km). A study in the Gulf of Mexi co alsoGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 48 noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in the Gulf of Mexico vs. the North Sea. Due to the limited scope and short duration of drilling activities proposed in this EP

, lighting impacts, collisions

, or other adverse effects are unlikely, and no significant impacts are expected.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore waters. It is likely that individual birds would experience, at most, only short

- term behavioral disruption

, and the impact would not be significant.



### Impacts of a Small Fuel Spill

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

. F or 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 spi ll 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 th e 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 d iscusses 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 a nd 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 area l 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

ar ea 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). Fo r this EP , there are no unique site

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

BOEMRE has reexamined the analys e s for coastal and marine birds presented in MMS (2007b, 2008) and determined that no new information was found that would a lter the potential impact s on marine and pelagic birds ( BOEMRE, 2011; BOEM, 2012 ).

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 sightedGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 49 seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2 . The number of pelagic birds that could be affected in open, offshore waters would depend on the extent and persistence of the
oil slick.

The recent Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pela gic species such as the Northern Gannet

, Magnificent Frigatebird, and Masked Booby (International Bird Rescue Research Center, 2010). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.



### C.4.2 Shorebird s and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non

- endangered birds are also found along the northern Gulf C oast, including diving birds, shorebird s, marsh birds, wading birds, and
waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, flats, dunes, bars, barrier islands, and similar
habitats include the Sandwic h Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull

- Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in recent lease sale EISs (MMS, 2007b, 2008).

The Brown Pelican ( Pelecanus occidentalis ) was delisted from Federal endangered status in 2009 (USFWS, 2010c). However, this species is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 2011) and as a species o f special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 201 1 )

. Brown Pelicans inhabit coastal habitats and forage within both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, in cluding
GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans live s in the northern Gulf Coast, g enerally nesting on protected islands (USFWS, 2010 b ).

The Southern Bald Eagle ( Haliaeetus leucocephalus ) was delisted from its threatened status in
the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed
across the s outhern U.S., including coastal habitats along the Gulf of Mexico. The Gulf C oast is inhabited by both wintering migrant and resident Bald Eagles (Johnsgard, 1990; Ehrlich et al., 1992).

IPFs potentially affecting shorebird s and coastal nesting birds incl ude support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely
to affect shorebird s or coastal nesting birds, as the lease area is 120 miles ( 194 km) from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2007

- G03 will minimize the potential for marine debris

- related impacts on shorebirds.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas n ear Port Fourchon and Houma, Louisiana, where shorebird s and coastal nesting birds may be found. These activities couldGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 50 periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary between species and between individuals (Rodgers and Schwikert, 20 02). 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). Flushi ng 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 acti vities, 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). How ever, 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.
Th is 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 simil ar 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, 2010 c ). According to the International Bird Rescue Research Center (2010), bird species that have been treated for
oilin g 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 TernGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 51 • Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling • Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

Coastal birds can be exposed to oil as they float on the water surface, dive during foraging, or
wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they can inges t 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 follow ing the Macondo spill, (USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in the event of a catasrophic spill reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cl eanup 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
northe rn Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the pl anktonic 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).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 52 

### 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,

orga nic 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 ele vated 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 perm it, 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 o nce

- through, non

- contact cooling of machinery

on the drilling rig. R ig s considered for use for activities described in this EP are not “new”
facilit ies as defined by the NPDES permit and therefore are not subject to the cooling water intake regulations fo r 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 impin gement. 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 d uring the route from cooling intake structure to discharge structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities , any short

- term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.



### Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resource s are discussed in recent EISs (MMS, 2007b, 2008)

. F or this EP , there are no unique site

- specific issues wit h respect to spill impacts.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 53 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 wou ld 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 meteorol ogical 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 ar ea 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 ex tent 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, zoopl ankton, 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, a nd 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 Fi shery Management Councils.

The BOEM (201 2 ) 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 co nclusions 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, shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pel agic 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). T he EFH
for most of these GMFMC

- managed species is on the continental shelf in waters sh allower 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 topographicGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 54 features on the Texas

- Louisiana OCS, the nearest of whic h is Ship Shoal South located in EW 947,
112 miles ( 181 km) north of the lease area along the shelf edge south of Louisiana.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include th e following species and life stages (NMFS, 2009):

• Atlantic bluefin tuna (spawn, eggs, larvae, adults)

• Bigeye thresher shark (all)

• Bigeye tuna (juveniles, adults)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Longfin mako shark (all)

• Oceanic whitetip shark (al l)

• Sailfish (adults) • Shortfin mako shark (all)

• Silky shark (all)

• Skipjack tuna (spawn, adults)

• Swordfish (larvae, juveniles, adults)

• Whale shark (all)

• White marlin (juveniles, adults)

• Yellowfin tuna (spawn, juveniles, adults)

Recent research indicates the central and western Gulf of Mexico may be important spawning habitat for Atlantic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of Mexico

, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 300,000 km 2 (15,000 mi 2 )

. The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern U.S. and Canad ian 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 ES A

. 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

i dentification from waters between 100 fathoms and the seaward limit of the Exclusive

Economic Zone ( EEZ )

. The Highly Migratory Species Fisheries Management Plan was amended

in 2009 to update EFH and HAPC to include the bluefin tuna spawning area ( NMFS , 20 09).

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, 2009 a,b ). A new EFH consultation has been initiated between BOEMRE’s Gulf of Mexico Region and NOAA’s Southeastern Region. Some EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the elements des cribed a bove will be followed ( BOEMRE, 2011; BOEM, 2012 ).

Other HAPCs have been identified by the GMFMC (2005). These include the Florida Middle Grounds, Madison

- Swanson Marine Reserve, Tortugas North and South Ecological Reserves,Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 55 Pulley Ridge, and sever al individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 )

. The nearest of these is Jakulla Bank

, located approximately 65 miles (1 05 km)
north west of the lease area.

Routine IPFs potentially affecting EFH include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents

– a small fuel spill and a large oil spill (WCD).



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

The drilling rig, as a floating structure in the deepwater environment, will act as a n FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (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 waste s, 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 pe lagic 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 du ration 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 mea sures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will help diminish the potential for impacts on EFH. EP Section H provides
detail on spill response measures. Given the open oce an location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008)

. F or this EP

, there are no unique site

- specific issues wi th 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 t he 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 hou rs. 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 56 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 w ould not affect EFH for corals and coral reefs, the nearest EFH being the topographic feature of Ship Shoal South located in EW 947, 112 miles ( 181 km) north of the
lease area. A small fuel spill would float and dissipate on the sea surface and would not contact
these features.



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

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008). For this EP

, there are no unique site

- specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially 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 shrimp, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would r esult 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 an d shellfish species.

T he lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or subl ethal impacts on spawning tuna. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The topographic f eature s of Ship Shoal South, located 112 miles ( 181 km) north of the lease area

in EW 947

, 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 (201 2 ) reexamined the analys e s for archaeological resources presented in MMS (2007b, 2008), b ased on additional information available since the publication of these two
documents and in consideration of the Macondo oil spill

. Substantial new information that alters the impact conclusion for archaeological resources presented in MMS (2007b, 2008) has come to light as a result of BOEMRE

- sponsored studies and industry surveys. Specifically,
evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to have occurred because of an incomplete knowledge of seafloor conditions in lease areas

>200 m (656 ft) deep that have been exempted from high

- resolution surveys. Since significant historic shipwrecks have recently been discovered outside the previously designatedGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 57 high

- probability areas (some of which show evidence of impacts from permitted activities prior to their discovery), beginning in 2011 a survey will be required for exploration and development projects. The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks . There were no indications of wrecks or other archaeological resources detected during the site clearance survey (GEMS , 201 1 ) . 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 eva luations have been completed.

Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. I mpacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect shi pwrecks because the oil would float and dissipate on the sea surface.



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

MMS (2007b) estimate d that a severe subsurface blowout could resuspend and disperse
sediments within a 300

- m (984

- ft) radius. Because there are no his toric 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 impa cts 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 no t well known, a subsurface plume could have the potential to contact shipwreck sites beyond the 300

- m (984

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

, depending on its extent, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the seafloor

, it could adversely affect their condition or preservation. Should there be any indication that potential shipwreck sites could be affected, in accordance
with NTL 2005

- G07 Anadarko will immediately halt operations, take steps to ensure that the site is not disturbed in any way

, and contact the BOEMRE Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. Anadarko would cease all operations within

305 m (1,0 00 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 sit e. A s 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 9 1 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 Pres ent (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).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 58 During periods that the continental shelf was exposed above sea level, the area was open to habitation by prehisto ric 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 leve l at 12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) bel ow the
present

- day sea level (CEI, 1977

, 1982). On this basis, the contine ntal shelf shoreward of the

45

- to 60

- m (148

- to 197

- ft) bathymetric contours has potential for pr ehistoric 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 archaeologica l site potential in Gulf of Mexico region

.

With a water depth of 1,367 m (4,484 ft)

, the wellsite is well beyond the 60

- m (197

- ft) depth contour used by the BOEMRE as the seaward extent for prehistoric archaeological site potential
in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources because the oil would float and dissipate on the sea surface.



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

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe
subsurface blowout could resuspend and disperse sediments within a 300

- m (984

- ft) radius.

Along the northern Gulf C oast, 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

p rehistoric 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 oile d sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).



## C.7 Coastal Habitats and Protected Areas

Co astal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities are described in recent EISs (MMS, 2007b, 2008) and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include bar rier 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.

D ue 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 a rea relate to support vessel
traffic . The support bases at Port Fourchon and Houma, Louisiana are not in a wildlife refuge or wilderness area. Potential impacts of support vessel traffic are addressed briefly below.

A small fuel spill in the lease area w ould be unlikely to affect coastal habitats, as the lease area is
120 miles ( 194 km) from the nearest shoreline (Louisiana) . As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 59 

### Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support operations, including crew boats and supply boats as detailed in EP Section K

, may have a minor incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and channels.



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

Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b, 2008). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP , there are no unique site

- specific issues with respect to
coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that during winter there is a

17 % probability of oil from a spil l in the lease area reaching shorelines in Texas within 120 days,
and a 14 % probability in spring of oil reaching Louisiana shorelines within 120 days.

The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include
extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries. National wildlife refuges and other protected

areas along the coast are discussed in a recent lease sale EIS (MMS, 2007b) and Anadarko ’s
OSRP. Coastal and near coastal wildlife refuges, wilderness areas , and State and National parks within the geographic range of the potential shoreline contacts after 120 days are presented in
Table 6

.

Table 6. W ildlife refuges, wilderness areas , and State and National parks within the geographic range of the potential shoreline contacts after 120 days (From: BOEMRE, 2011)

.

County or Parish , State W ildlife Refuge, Wilderness Area, or State/National Park

Cameron County, Texas Lower Rio Grande Valley National Wildlife Refuge
Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park Andy Bowie County Park Laguna Madre Estuarine and Coastal Marine Area

Willacy County, Texas Lower Rio Grande Valley National Wildlife Reserve Laguna Atascosa National Wildlife Reserve

Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine and Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park

Port Aransas Park

Mission

- Aransas National Estuarine Research Reserve

Aransas County, Texas Mission

- Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Goose Island State ParkTable 6. (Continued).

Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 60 County or Parish , State W ildlife Refuge, Wilderness Area, or State/National Park

Calhoun County, Texas Mission

- Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge Matagorda Island State Park Guadalupe Delta Wildlife Management Area

Welder Flats Coastal Preserve

Matagorda County, Texas Big Boggy National Wildlife Refuge

Aransas National Wildlife Refuge

Mad Island Wildlife Management Area

San Bernard National Wildlife Refuge

Brazoria County, Texas San Bernard National Wildlife Refuge

Peach Point Wildlife Management Area

Brazoria National Wildlife Refuge Christmas Bay Coastal Preserve and Christmas Bay State Park

Galveston County, Texas Galveston Island State Park

Brazoria National Wildlife Refuge Apffel Park

Seawolf Park

Old Fort Travis Park

Atkinson Island Wildlife Management Area

Ft. Anahuc Park

Anahuac National Wildlife Refuge

Mc F addin National Wildlife Refuge

Jefferson County, Texas Mc F addin National Wildlife Refuge

Sea Rim State Park Murphree Wildlife Management Area

Texas Point National Wildlife Refuge

Cameron Parish, Louisiana Sabine National Wildlife Refuge

Cameron Prairie National Wildlife Refuge

Lacassine National Wildlife Refuge

Little Pecan Island Natural Area

Peveto Woods Natural Area

Lower Neches Wildlife Management Area

Rockefeller Wildlife Management Area

Vermilion Parish, Louisiana Louisiana Rockefeller Wildlife Management Area Paul J. Rainey Wildlife Management Area

Plaquemines Parish, Louisiana Salvador Wildlife Management Area

Jean Lafitte National Historical Park and Preserve
Delta National Wildlife Refuge

Pass

- a

- Loutre Wildlife Management Area

Breton National Wildlife Refuge

St. Bernard State Park

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil

- and

- water mousse, or tarbal ls (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 incorpor ate 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 61 Oozing may also serve to expand the size of a mass as it incorporates beach mate rials. 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 (200 7b) 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 wet lands 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 ra tes, which have been reported to require from years to decades following a spill (MMS, 2007b).



## C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEMRE has reexamined the analysis for recreational and commercial fishing presen ted in

MMS (2007b, 2008) based on additional information and in consideration of the Macondo spill.

N o new information was found that would alter the potential impact s on commercial fishing ( BOEMRE, 2011; BOEM, 2012 )

.
The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and

summ er. I n 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, w ith 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). Tilefish es (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).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 62 Most recreational fishing activity in the region occurs in water depths less than 200 m (656 ft) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum rig s offshore Texas and Louisiana. Due to the distanc e 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) and t wo types of potential accidents are also address ed 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 wh en placing their sets. Therefore, little or no impact on pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent di scharges 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 w ill 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 provi de s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Pelagic longlining activities in the lease area, if any, could be interrupted i n 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 ve ssels 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)

Pote ntial 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 effectiven ess 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, 2010 d ). At its peak on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Gulf of Mexico EEZ.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 63 

### 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, implemen tation of
Anadarko ’s OSRP will potentially alleviate the potential for impacts. EP Section H provide s detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 120 miles ( 194 km) from the nearest shoreline (Louisiana) and nearly all of the diesel fuel would evaporate or disperse na turally 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 ).



### Im pacts 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 P ollution 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, t he 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 pos e 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 o ffshore vessels or providing direct oversight to o ffshore 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

t han 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 sou ght medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S , 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 areGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 64 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, servic es, 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 measure s during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H provide s detail on spill response measures. Given the o pen 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 e xisting facilities, resources, and personnel.



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

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008).
For this EP , there are no unique site

- specific issues with respect to employm ent 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 resu lt 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 a ddition to the analys e s presented by MMS (2007b, 2008 ) and BOEM (201 2 ), a recent study explored the economic impacts of the Macondo spill on oil and gas industry employment due to suspension of deepwater drilling (Inter

- Agency Economic Report, 2010). The study indicates that during the moratorium, the number of oil industry workers in the Gulf of Mexico fell by about 2,000 and may have indirectly caused a temporary loss of 8,000 to 12,000 jobs along the Gulf Coast. Total spending by drilling operators is estimated to have declined by $1.8 billion

over a 6

- month period; this direct reduction in spending affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spend ing (Inter

- Agency Economic Report, 2010)

.



### C.8.4 Recreation and Tourism

BOEMRE has reexamined the analys e s for recreation and tourism presented in MMS (2007b, 2008) based on additional information and in consideration of the Macondo oil spill event. N o new information was found that would alter the potential impact s on recreation and tourism ( BOEMRE, 2011; BOEM, 2012 ).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by a ny routine activities due to the distance from shore. Compliance with NTL 2007

- G03 will minimize the chance of trash or debris being lost overboard from the drilling rig and subsequently washing up on beaches.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 65 

### 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 impac ts.

EP Section H provide s detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely t o affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area, and as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.



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

Potential impacts of an oil spill on recreation and tourism are discussed in recent EISs (MMS, 2007b, 2008). For this EP , there are no unique site

- specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and

we tlands, resulting in negative publicity that encourages people to stay away. Based on the
revised OSRA modeling (BOEMRE, 2011) as summarized in Section A.9.3 ( Table 3 )

, there is a

14 % probability in winter of oil from a spill in the lease area reaching sh orelines in Texas and a

14 % chance in spring of contacting shorelines in Louisia na 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 o ver a 3

- year period at $22.7 billion (Oxford Economics, 2010)

.



### C.8.5 Land Use

Land use along the northern Gulf C oast is discussed in recent lease sale EISs (MMS, 2007b, 2008). There are no routine IPFs potential ly affecting land use. The project will use existing onshore support facilities in Louisiana . The land use at the existing shorebase sites is industrial. The project will not involve any new construction or changes to existing land use and, therefore,
wil l 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 shorebase s

.
A large oil spill (WCD) is th e 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, d uring the Macondo spill, temporaryGreen Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 66 staging areas were established in L ouisiana, 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

respons e is demobilized.



### C.8.6 Other Marine Uses

The lease area is not located within any USCG

- designated fairway or shipping lane or Military Warning Area. Anadarko will comply with BOEMRE requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

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 o n other marine uses because spill response activities would be mainly within
the lease area and the duration would be brief.



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

An accidental spill would be unlikely to significantly affect shipping or other marine uses. Th e block s are not located within any USCG

- designated fairway or shipping lane. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Anadarko will comply with BO EMRE 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

- dis turbing activities occur near the existing pipelines and flowlines.



## D. Environmental Hazards

D.1 Geologic Hazards

The geohazard and site clearance survey s conducted by GEMS ( 2003

, 20 11 ) conclude d that the
wellsite is free of any significant geological hazards a nd 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 pr oposed activities. Extreme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rig s under consideration for this project . High winds and limited visibility during a severe storm could di srupt 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.Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 67 

## 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 e ffect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drilling rig s under consideration for this project . High waves during a severe storm cou ld disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes.



## E. Alternatives

N o formal alternatives we re evaluated in this EIA for an EP . However, various technical and operational options

, including the location of the wellsite and the selection of a drilling unit, were considered by Anadarko in developing the proposed action.



## F. Mitigation Measures

The proposed acti on includes numerous mitigation measures required by laws, regulations, and

BOEMRE lease stipulations and NTLs. The project will comply with all applicable F ederal, S tate, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project activities will be conducted under guidance by Anadarko’s OSRP and will
include the measures described in EP Section H

.



## G. Consultation

No persons or agencies were consulted during the preparation of this EIA.



## H. Preparers

The EIA was prepared by CSA International, Inc. Contributors included

• M. John Thompson (Senior Scientist);

• Carlyle Kalloo (Senior Scientist);

• Neal Phillips, Ph.D. (Senior Scientist);

• Luis Lagera , Jr., Ph.D. (Senior Scientist);

• Keith VanGraafeila nd (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director ) ; and

• Kim Dunleavy (Technical Editor).Green Canyon Blocks 683 and 727 September 2012 Environmental Impact Analysis Page 68 

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### O ADMINISTRATIVE INFORMATION

(a) Proprietary Information

Proprietary copies of this plan contain inform ation not available to the public and include structure maps, seismic information, cross sections, depths of wells, etc.

(b) Bibliography

Shallow Hazards Report Final Sale Package for Western Gulf of Mexico Sale Number 166 and 157.