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-07615

Type - Supplemental Exploration Plan

Lease(s) - OCS-G20725 Block - 646 East Breaks Area

Operator - Anadarko Petroleum Corporation
Drill & Complete - Well(s) EE and EEE

DP Semisubmersible, Drillship

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

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

Mohammad Ashfaq Plan Coordinator Description -

Rig Type - Subject: From: August 5, 2013

### SUPPLEMENTAL EXPLORATION PLAN (S-7615)

ANADARKO PETROLEUM CORPORATION

EAST BREAKS BLOCK 646 OCS-G 20725



## PUBLIC COPY

RECORD OF CHANGE LOG

Submission Type Date Sent to BOEM Summary of Submission Page
Numbers Initial 5/15/2013 Supplemental EP Submission. All Amendment 6/4/2013 Updated to correct well name to Location EE on Form 137, increase days to drill/complete well from 90 days to 105 days. Include additional well locations previously approved for East Breaks 646 in Section A. Updated Air Quality Emissions data to reflect increase in days to drill/complete well(s). Clarified drilling fluids transportation information and update discharge data. Also updated Environmental Impact Assessment to denote 105 days/well instead of 90 days/well. Initially submitted 5/31/2013, requested to re-send 6/4/2013. 4-8, 36-37, 38-39, 56, 57-59, 62-63

Amendment 6/28/2013 Update Solid and Liquid Wastes Transportation and Waste Disposal tables in Section F, K and L to also denote rate as days per well. Also include rate for cuttings wetted with synthetic based mud in Section F. 37, 58-59,
62-63

Final Copy of
Plan 7/23/2013 Complete EP Submittal to include all amendments submitted to
date. All

Add Record of Change Log 7/23/2013 Add Record of Change Log 1

# PUBLIC

SUPPLEMENTAL EXPLORATION PLAN

EAST BREAKS BLOCK 646 OCS-G 20725

OFFSHORE, TEXAS

Anadarko Petroleum Corporation
1201 Lake Robbins Drive The Woodlands, Texas 77380 Contact: Bridget O’Farrell Bridget.OFarrell-Villarreal@anadarko.com (832) 636-1694

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



### May 2013

## SUPPLEMENTAL EXPLORATION PLAN LEASE OCS-G 20725 East Breaks Block 646

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

## SECTION A PLAN CONTENTS

(a) Plan Information Form

Under this Supplemental Exploration Plan (EP) , Anadarko Petroleum Corporation (Anadarko) proposes to drill and complete two wells in East Breaks Block 646, Locations “EE” and “EEE”. Both wells will have their surface and bottom- hole locations in East Breaks Block 646. East Breaks Block 646, Location EE was previously a pproved under Plan Control No.: S-7363 and is being updated to meet current requi rements. East Breaks Block 646, Location EEE is approximately 100' East of East Breaks Block 646, Location EE. The wells will be drilled using a drillship or dynamically posit ioned (DP) semi-submersible drilling rig. Drilling and completion operations for all well locations will utilize a Subsea BOP stack. OCS Plan Information Form BOEM-137 is enclosed as Attachment A-1.

(b) Location

Enclosed as Attachment A-2 is a well location plat at a scale of 1 inch = 2,000 feet that depicts the surface locations and water depth of the proposed wells.

(c) Safety and Pollution Prevention Features

Safety features on the drilling rig will include well control, pollution prevention, safe welding procedures, and blowout prevention equipment as described in Title 30 CFR Part 250, Subparts C, D, E, G and O; and as fu rther clarified by BOEM/BSEE Notices to Lessees, and applicable regulations of the Environmenta l Protection Agency and the U.S. Coast Guard. The appropriate life rafts, life jackets, ring buoys, etc., as prescr ibed by the U.S. Coast Guard, will be maintained on the facility at all times.

### (d) Storage Tanks and Production Vessels

The proposed wells will be drilled with a dr illship or DP semi-subm ersible drilling rig.

Type of Facility Type of Storage Tank Tank Capacity Numbe r 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 Settling
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-submersible Fuel Oil Hull
Tanks 4,541 bbls 2 9,082 bbls No. 2 Diesel 7 tanks total= 16,689 bbls

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

Fuel Oil Deck Day
Tank 629 bbls 1 629 bbls No. 2 Diesel

Fuel Oil Deck Settling Tank 164 bbls 1 164 bbls No. 2 Diesel

Fuel Oil Emergency Generator 30 bbls 1 30 bbls No. 2 Diesel

### (e) Pollution Prevention Measures

The drilling rig utilized for these operations will comply with all applicable regulations regarding pollution prevention and control. The rig has a Shipboard Oil Pollution Emergency Plan (SOPEP), which is reviewed and approved annually by the American Bureau of Shipping (ABS). The SOPEP is provided to assist employees in d ealing with an unexpected discharge of oil. Its primary purpose is to set in motion the necessary actions to stop or minimi ze the discharge of oil and to mitigate its effects. Effective planning en sures that the necessary actions are taken in a structured, logical 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 pla n. The activities proposed in this plan are not located offshore Florida.

(g) Description of Previously Approved Lease Activities

Anadarko has previously approved well lo cations in East Breaks Blocks 646.

Control # Plan Type/Approval Well Location(s) Status of Well Location

N-6750 Initial EP Approved 3/30/2000 EB 602 SL / EB 646 BL
A
B C Drilled as EB 646 001. Drilled as EB 646 005. Drilled as EB 646 002. S-5381 Supplemental EP Approved 10/12/2000 EB 602 SL / EB 646 BL
D
E Drilled as EB 646 003. Open location for future drill site. S-5648 Supplemental EP Approved 7/13/2001 EB 646 F Open location for future drill site.

S-5787 Supplemental EP Approved 11/29/2001 EB 646 SL / EB 690 BL
D Open location for future drill site.
N-7320 Initial EP Approved 12/18/2001 EB 646 SL / EB 689 BL
A Open location for future drill site: S-5788 Supplemental EP Approved 1/8/2002 EB 646 G Drilled as EB 646 006.

S-7170 Supplemental EP Approved 2/12/2008 EB 646
BB
DD Drilled as EB 646 SS007 ST01. Drilled as EB 646 SS008.Control # Plan Type/Approval Well Location(s) Status of Well Location
S-7259 Supplemental EP Approved 2/26/2009 EB 646 AA, CC Open locations for future drill sites. (AA to be used as #010 well.) S-7363 Supplemental EP Approved 11/19/2009 EB 646 EE, GG, HH Open locati ons for future drill sites. (GG to be used as #009 well.)
R-5148 Revised EP Approved 10/21/2011 EB 646 #009 (GG), #010 (AA) Open loca tions for future drill sites.

N-9591 Initial/Supplemental EP Approved 12/1/2011 EB 645 AA, EE EB 646 FF, MM Open locations for future drill sites. Open locations for future drill sites.

N-7045 Initial DOCD Approved 7/18/2001 EB 602 Structure A

EB 602
1
2

3
4
5
6
7
9

EB 602 SL / EB 646 BL
1
2

3
4 Previously installed, name d EB 602 A (Nansen Spar).

Named EB 602 001, sidetracked. Placed on production, named EB 602 A009 ST01. Currently plugged and abandoned. Placed on production, na med EB 602 A005 ST01. Placed on production, na med EB 602 SS004 ST01. Placed on production, na med EB 602 A003 ST01. Placed on production, named EB 602 A007. Placed on production, na med EB 602 SS007 ST01. Placed on production, na med EB 602 SS009 ST01.

Placed on production, na med EB 646 A006 ST01. Placed on production, name d EB 646 A008 ST02 BP03. Currently plugged and abandoned. Placed on production, named EB 646 A004. Placed on production, named EB 646 A001.
N-7494 Initial DOCD Approved 10/1/2003 EB 646 SL / EB 689 BL
001

EB 646 006 Placed on production, named EB 689 SS001.

Placed on production, named EB 646 SS006. S-7297 Supplemental DOCD Approved 2/5/2009 EB 646 009 Subsea well, not yet drilled.

S-7250 Supplemental DOCD Approved 1/30/2009 EB 646 SS No.7
EB 646 SS No.8 Placed on production, na med EB SS007 ST01. Placed on production, named EB 646 SS008.U.S. Department of the Interior OMB Control Number: 1010-0151 Bureau of Ocean Energy Management OMB Approval Expires: 12/31/14



### OCS PLAN INFORMATION FORM

General Information
Type of OCS Plan: Exploration Plan (EP) Devel opment Operations Coordination Document (DOCD)

Company Name: BOEM Operator Number:

Address: Contact Person:

Phone Number:

E-Mail Address:

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

Project and Worst Case Discharge (WCD) Information
Lease(s): Area: Block: Project Name (If Applicable):
Objective(s) Oil Gas Sulphur Salt Onshore Support Base(s):

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

Distance to Closest Land (Miles): Volume from uncontrolled blowout:
Have you previously provided information to verify the calculations and assumptions for your WCD? Yes No

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

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

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

Do you propose any facility that will serve as a host facility for deepwate r subsea development? Yes No
Description of Proposed Activities and Tentative Schedule (Mark all that apply)
Proposed Activity Start Date End Date No. of Days
Exploration drilling and completion–Location E E
Exploration drilling and completion–Location EE E

Installation or modification of structure

Installation of production facilities

Installation of subsea wellheads and/or manifolds

Installation of lease term pipelines

Commence production
Other (Specify and attach description)
Description of Drilling Rig Description of Structure
Jackup Drillship Caisson Tension leg platform
Gorilla Jackup Platform rig Fixed platform Compliant tower

Semisubmersible Submersible Spar Guyed tower

DP Semisubmersible Ot her (Attach Description)

Drilling Rig Name (If Known): Floating production system Other (Attach Description)

Description of Lease Term Pipelines
From (Facility/Area/Block) To (Facility/Area/Block) Diamet er (Inches) Length (Feet)

Form BOEM- 0137 (December 2011 - Supersedes all previous editi ons of this form which may not be used.)OCS PLAN INFORMATION FORM ( CONTINUED ) Include one copy of this page for each proposed well/structure Proposed Well/Structure Location

Well or Structure Name/N umber (If renaming well or structure, reference previous name): Previously reviewed under an approved EP or
DOCD? S-7363 Yes No

Is this an existing well
or structure? Yes No If this is an existing we ll or structure, list the Complex ID or API No. Do you plan to use a subsea BOP or a surface BOP on a floa ting facility to conduct your proposed activities? Yes No

WCD info For wells, volume of uncontrolled blowout (Bbls/day): For structures, volume of all storage and pipelines (Bbls): API Gravity of fluid

Surface Location Bottom-Hole Location (For Wells) Completion (For mult iple completions, enter separate lines)

Lease No. OCS OCS OCS
OCS

Area Name

Block No.

Blockline Departures (in feet) N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L N/S Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L E/W Departure: F____ L

Lambert XY coordinates X: X: X:
X:
X:

Y: Y: Y:
Y:
Y:
Latitude/ Longitude Latitude Latitude Latitude
Latitude
Latitude Longitude Longitude Longitude Longitude Longitude Water Depth (Feet): MD (Feet): TVD (Feet):

Anchor Radius (if applicable) in feet: MD (Feet): MD (Feet): MD (Feet): TVD (Feet): TVD (Feet): TVD (Feet):

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

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

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Form BOEM- 0137 (December 2011 - Supersedes all previous editions of this form which may not be used.)OCS PLAN INFORMATION FORM ( CONTINUED ) Include one copy of this page for each proposed well/structure Proposed Well/Structure Location

:HOORU6WUXFWXUH1DPH1XPEHU,IUHQDPLQJZHOORU VWUXFWXUHUHIHUHQFHSUHYLRXVQDPH 3UHYLRXVO\UHYLHZHGXQGHUDQDSSURYHG(3RU
'2&'"  <HV  1R

,VWKLVDQH[LVWLQJZHOO
RUVWUXFWXUH" <HV 1R ,IWKLVLVDQH[LVWLQJZHOORUVWUXFWXUHOLVWWKH &RPSOH[,'RU$3,1R 'R\RXSODQWRXVHDVXEVHD% 23RUDVXUIDFH%23RQDIORDWLQJIDFLOLW\WRFRQGXFW\RXUSURSRVHGDFWLYLWLHV"  <HV  1R

WCD info )RUZHOOVYROXPHRIXQFRQWUROOHG EORZRXW%EOVGD\ )RUVWUXFWXUHVYROXPHRIDOOVWRUDJHDQG SLSHOLQHV%EOV $3,*UDYLW\RI IOXLG

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

Lease No. 2&6 2&6 2&6
2&6

Area Name 

Block No.

Blockline Departures (in feet) 16'HSDUWXUH)BBBB/ 16'HSDUWXUH )BBBB/ 16'HSDUWXUH )BBBB/ 16'HSDUWXUH)BBBB/ 16'HSDUWXUH)BBBB/ (:'HSDUWXUH)BBBB/ (:'HSDUWXUH)BBBB/ (:'HSD UWXUH)BBBB/ (:'HSDUWXUH)BBBB/ (:'HSDUWXUH)BBBB/

Lambert XY coordinates ; ; ;
;
;

< < <
<
<
Latitude/ Longitude /DWLWXGH /DWLWXGH /DWLWXGH
/DWLWXGH
/DWLWXGH /RQJLWXGH /RQJLWXGH /RQJLWXGH /RQJLWXGH /RQJLWXGH :DWHU'HSWK)HHW 0')HHW 79')HHW

$QFKRU5DGLXVLIDSSOLFDEOHLQIHHW 0')HHW 0')HHW 0')HHW 79')HHW 79')HHW 79')HHW

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

;  < 

;  < 

;  < 

;  < 

;  < 

;  < 

;  < 

;  < 

Form BOEM- 0137 'HFHPEHU

- 6XSHUVHGHVDOOSUHYLRXVHGLWLRQVRIWKLVIRUPZKLFKPD\QRWEH XVHG EEE 

## X

X

X

N/A

G 20725

East Breaks

646

512' FNL

1,908' FWL

1,158,230'

9,931,168'

27.360084 (27° 21' 36.302")

-94.485972 (-94° 29' 9.4992")

3,637'

N/A-Using DP Vessel N/A N/A-Less than N-9591

### SECTION B GENERAL INFORMATION

(a) Applications and Permits

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

Application/Permit Issuing Agency Status
Permit to Drill Bureau of Safety and Environmental Enforcement (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 7,000 bbls

Synthetic-based (internal olefin, ester) 12,500 bbls
Oil-based N/A

(c) Oils Characteristics

Oil will not be produced under this Supplemen tal Exploration Plan. Therefore the oils characteristics information is not require d per NTL 2008-G04 2(d), extended by NTL BOEM
2013-G02.

(d) New or Unusual Technology

Anadarko does not propose to use any new or u nusual technology to drill the wells proposed in this plan.

(e) Bonding Statement

The bond requirements for the activities and facili ties proposed in this EP are satisfied by an area-wide bond furnished and maintained accord ing to 30 CFR Part 556, subpart I; NTL 2000- G16, “Guidelines for General Lease Sure ty Bonds,” and National NTL 2008-N07, “Supplemental Bond Procedures”.

(f) 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 553, and NTL 2008-N05, “Guidelines for Oil Sp ill Financial Responsibility for Covered Facilities”.

### (g) Deepwater Well Control Statement

Anadarko Petroleum Corporation (Company Number 00981) has the financia l capability to drill a relief well and conduct other emergenc y well control operations if required.

(h) Blowout Scenario

Anadarko prepared this blowout scenario pursu ant to guidance provided in NTL 2010-N06. The previously approved East Breaks Block 645, Loca tion EE well is addressed in this blowout scenario since it was the location with the highest potential worst case discharge (WCD) rate for East Breaks Block 645/646, approved under Plan Control No.: N-9591. A similar approach would be taken in the event of a blowout for th e wells covered under this plan in East Breaks
646.

Based on NTL 2010-N06 guidance, the maximum hydrocarbon discharge for East Breaks Block 645 was calculated to be 155,400 bopd (approved under Plan Control No: N-9591). The worst case discharge for East Breaks Block 646 was 139,700 bopd (approved under Plan Control No.: N-9591). Anadarko has calculated the worst case disc harge for the proposed East Breaks Block 646, Location EE and EEE, and found it to be less than what was approved under Plan Control No.: N-9591 (for either block).

Purpose This overview provides a generic blowout scenario, additional information regarding any potential oil spill, and the measures Anadarko w ill take to prevent a blowout and if necessary promptly respond to manage a blowout scenario if one occurs. A similar approach would be taken to manage a blowout for East Breaks Bloc k 646 or 645. Therefore the worst case for East Breaks Block 645 is referenced since it was higher than East Breaks Block 646. (As approved under Plan Control No.: N-9591.) The following information is pursuant with 30 CFR 250.213(g), 250.219, 250.250 and NTL 2010-N06.

Information Requirements:

Blowout Scenario

The previously approved East Breaks Block 645, Location EE exploration well (Plan Control No.: N-9591) is to be drilled utilizing a using a MODU rig with a marine riser and sub-sea BOP. A typical sub-sea wellhead system, conductor, surface and intermediate casing program will be
used.

The Blowout Scenario assumes that a hydroc arbon influx occurs followed by a well control event from the objective sands. The sub-sea BOP and marine riser subsequently fail followed by a blow out to the seabed. The Worst Case Di scharge (WCD) scenario assumes 10-5/8" Open Hole with a 13-5/8" intermediate casing string a nd an 11-7/8" liner set as per attached wellbore
schematic.

### Estimated flow rate of the potential blowout:
Category Initial/Supplemental EP* Type of Activity Exploration Drilling Facility Location (area/block) EB 645 Facility Designation “EE” Distance to Nearest Shoreline (miles) 118 miles Uncontrolled blowout (volume per day) 155,400 bbls Type of Fluid(s) Crude

* Approved under Plan Control No.: N-9591 for East Breaks Block 645 and 646. The worst case discharges for East Breaks Block 646 are less than the East Breaks Block 645, but a similar approach would be taken in the event of an incident.



### a) Potential for the well to bridge over:

Mechanical collapse of th e shallow reservoirs in a blow ou t scenario is considered likely from the production history of the Nansen fiel d. This mechanical failure attributed to sand has occurred in 44% of the completions. The wells that were completed, produced,
and then failed are:

 EB 646 #4 ST01 (A-2) – 1.5 MMBO, 6.2 BCFG, 0.9 MBW

 EB 602 #2 (A-9) – 1.1 MMBO, 12.6 BCFG, 261 MBW

 EB 646 #2 ST04 (A-8) – 0.3 MMBO, 5.7 BCFG, 397 MBW

 EB 602 #7 – 12.4 MMBO, 84 BCFG, 96 MBW

b) Likelihood and measures taken for surface and/or sub-sea intervention to stop the
blowout:

The likelihood of surface intervention to prev ent, or stop, a blowout is high and is based on the following equipment specific to a capable MODU that will be contracted to do this drilling program:

 ROV Secondary BOP Control System: The BOP will be confirmed to have an ROV Intervention Panel and circuits that have the following attributes:

 Hot stab capable of closing one set of:

 Blind-Shear Rams – One Set

 Pipe Rams – One Set

 Unlatch the Lower Marine Riser Package

 Hot stab has been function tested in conjunction with the Stump Test and was tested at the same rate and pressure as the pump installed on the ROV used by the rig.

The panels capable of also be ing operated by an ROV from an independent supply boat in the ev ent of a loss of rig scenario.

###  Deadman / Autoshear function: Th e rig to be equipped with an automated sequence that closes the blind shear rams in the event of any of the following scenarios:

 Inadvertent disconnect of the LMRP

 Loss of both hydraulic pressure an d electrical supply from the surface BOP control system

No human interface is to be required once these systems are armed.

c) Availability of a rig to drill a relief well: Per the preliminary Mutual Aid agreements that are being worked between E&P Operators in the Gulf of Mexico, Anadarko will select from the best rig option available in the Gulf of Mexico fleet if and when it is required for relief well work. As of May 15, 2013 there were 15 additional rigs in the Gulf of Mexico which would be capable of operating under the conditions asso ciated with drilling a relief well for this prospect. A rig which could be used to drill a relief well is the Ensco 8500 which is a dynamically positioned semi-submersible drilling rig capable of operating in the water depths, and drilling to the total well depths, associated with a relief well for this prospect. The rig is currently under contract to Anadarko and is on location operati ng in Keathley Canyon Block 875 (SHL)/919 (BHL).

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 with a 15,000 psi BOP Stack and capable of drilling in 3,750' of water is required for any relief well operations . (Note, for East Breaks Block 646 a rig with a 15,000 psi BOP Stack and capable of drilling in 3,637' of water would be required.)

e) Time taken to mobilize a rig and drill a relief well: An estimated 7-21 days is required to suspend operations on a deepwater GOM well, mobilize to a relief well loca tion, and begin relief well drill ing operations. This estimate includes 0-14 days to suspend current opera tions on an existing well and 7 days to
mobilize to location and be r eady to spud a relief well. The estimated time to drill the relief well and perform kill operations is 153 days for an estimated total of 160-174 days from time of blowout to finishing a relief well.

### The time estimate provided for the plan well is inclusive of 'both' drilling 'and' completion operations. As a completion is no t typically part of relief well operations no time has been included for completion operations in the relief well estimate. Therefore the estimated time for a relief well should be less than for the plan well. In addition, information and learning from the drilling of the original well ma y provide opportunities to optimize drilling performance for relief we ll operations and thus reduce the required drilling time.

f) Assumptions and calculations used in a pproved or proposed Oil Spill Response
Plan:

Regional OSRP–Garden Banks Block 346

 For the OSRP exploratory worst case di scharge scenario only the Area/Block is referenced in the OSRP. Exploratory dril ling facility designati ons (proposed well location names) are typically not included in the OSRP.

 Petroleum Expert’s Prosper software was used for the nodal analysis. The WCD for the Garden Banks Block 346 #002 (Locati on A) is 321,108 bbls of oil per day.

 The maximum total volume during a bl owout could potentially be 37,890,744 bbls assuming 118 days for the maximum duration of a blowout.

 The volume denoted in the Regional OSRP is higher than the NTL 2010-N06 (256,700 bopd) and BOEM (321,108 bopd) calcul ations approved under the Initial EP (Plan Control No.: N-9579). Anadarko elected to denote a higher volume (350,000 bbls) in the Regional OSRP for planning purposes to de monstrate equipment response capabilities per prev ious discussions w ith Rusty Wright.

Supplemental EP–East Breaks Block 645, Lo cation EE (Approved un der Plan Control No.: N-9591)

 Nodal analysis was performed to calculate worst case discharge volumes. The result being that at the seafloor, the estimated worst case discharge for the well is 155,400 bopd.

 The maximum total volume during a bl owout could potentia lly be 27,039,600 bbl assuming 174 days for the maximum durati on of a blowout, multiplied by the worst case daily uncontrolled blowout volume of 155,400 bbl / day.

* Approved under Plan Control No.: N-9591 for East Breaks Block 645 and 646. The worst case discharges for East Breaks Block 646 are less than the East Breaks Block 645, but a similar approach would be taken in the event of an incident.

### g) Measures taken to enhance the ability to prevent or reduce the likelihood of a
blow-out

 Well design : Anadarko utilizes a systematic we ll design process for the planning and construction of a well operation. This pro cess utilizes the de pth of experience Anadarko possesses in the Deepwater aren a and involves a multi-disciplinary team peer review of the well design, shallow h azards, and formation pressure hazards expected during the drilling pha se of the well. This process minimizes the potential for an unplanned well control event that coul d lead to a blowout. This process will also include Professional Engineer review and certification of the final casing design and cementing program.

A detailed pre-drill assessment of form ation pressure provided by Anadarko’s Geologic/Geophysical team, along with th ird party consultants, allows for development of a mud program that provi des an overbalanced mud weight for the safe drilling of the well. For an expl oration well this may also include taking formation pressures to confirm the act ual formation pressure during the well construction process and minimize the risk of an unplanned well control event. The pore pressure environment is understood due to the numerous offset wells previously
drilled in the Nansen Field.

The well construction process also require s a systematic review and management acceptance of the start-up preparation work for the rig and crews along with the third party technical audit work on the rig and the rig’s well control equipment. This review and audit process measures the ri g’s ability to handle an unplanned well control event and provides assurance that the rig can successfully mitigate a loss of well control event and prevent it fr om becoming a blowout scenario.

 Barrier Philosophy: For all well designs, Anadar ko requires and uses a redundant barrier philosophy, that being two independent barriers for both internal and external flow paths in the final wellbore. It is also standard practi ce to conduct pressure testing, in accordance with the applicable regulations, to evaluate integrity on all relevant barriers. In addition, all intermed iate and production casings returned to the wellhead will be locked down before subse quent wellbore constr uction proceeds.

###  BOP and well control equipment: The rig will have an 18-3/4" 15,000 psi BOP with primary and secondary BOP control systems. The BOP will have been completely recertified compliant to OEM sp ecifications and all applicable federal regulations by a qualified third party. Prio r to commencement of operations at the East Breaks Block 645, Location EE well an in dependent third party verification will be obtained to verify that the subsea BOP is designed fo r the specific equipment on the rig and this specific well design.

 BOP and well control equipment testing : To ensure effectiveness of the BOP and well control equipment, a testing program will be conducted prior to running the BOP and then during the well operations at the East Breaks Block 645, Location EE well. This testing program will be in compliance with applicable federal regulations for pressure and function testing and will al so provide periodic assessment 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 contract or personnel to hold a WellCAP, or equivalent, well control traini ng certificate, renewable ever y two years for the type of floating drilling operation being conducted. Anadarko also monitors compliance of its personnel with the applicable federal regulations, including those found in 30 CFR Part 250 Sub-Part O.

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

h) Arrangements for drilling a relief well

 Anadarko maintains a master agreement with Wild Well Control for advice, management, engineering, well kick pre and post modeling, and resource support for an unplanned loss of well control event. In the event of any well control event, Wild Well Control would be cont acted and mobilized if re quired to support Anadarko’s operational team both in the onshore and offshore locations. This agreement and expertise, along with additional equipmen t access, enhances th e ability to conduct effective and early interventi on in the event of a blowout.

 The conceptual relief well design will be sim ilar to the design of the original well in that casing weights, grades a nd setting points are anticipate d to be identical or very similar. The conceptual well design is not anticipated to require more than two days to finalize upon initialization.

###  A block wide shallow hazard assessment has been completed for East Breaks Blocks 645 and 646. (Associated with Plan Control No.: S-7363 and N-9591.) Furthermore, the potential for high density chemo-synt hetic communities in the study area are negligible. Depending on the nature of the blowout scenario, well geometry, and total depth required to intersect the blowout, th e most suitable surface location will be chosen and submitted for approval as the location for the relief well.

 Anadarko’s philosophy is to carry an adequate inventory of well construction equipment to drill a complete well(s) from surface to total depth. Back-up long lead equipment equivalent to the original well design will be carried in stock to allow a rapid response. This includes a spare deepwater sub-sea wellhead system and the large OD casing (36", 22", 18", 16", and 13-5/ 8") and connectors re quired for the first part of the well. Smaller OD casing is considered readily available on the ground in the GoM and would be resourced out of ex isting inventory or from suppliers as required.

 Existing service agreements will be in pl ace for support services including drilling fluids, casing running, cementing, ROV’s, so lids control, mud logging, directional drilling, LWD/MWD, logging, boats and helicopters.

 Specialist services for range finding to dri ll the relief well in close proximity to the original wellbore at the re servoir depth may potentially be provided through Vector Magnetics LLC. Baker-Hughes, Halliburton and Schlumberger have in-house personnel to supplement Vector Magnetics under our existing directional drilling agreements.

### SECTION C GEOLOGICAL AND GEOPHYSICAL INFORMATION

(a) Geological Description

Discussions regarding geologic information are considered proprietary and have been omitted from this public copy of the EP. Note, some attachments have been not included due to proprietary information.

(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 a nd locations of geological cross-sections, were
enclosed as Attachment C-1 in the Confidential version of the EP and have been omitted from this public copy of the EP

.

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

Interpreted seismic lines were enclosed as Attachment C-2 in the Confidential EP version and have been omitted from this public copy of the EP

.

(d) Geological Structure Cross-Sections

Interpreted geological structure cross-sections showing the locat ion and depth of each proposed well were enclosed as Attachment C-3 in the Confidential version of the EP, and have been omitted from this public copy of the EP

.

(e) Shallow Hazards Report

A Shallow Hazards Report for East Breaks Block 646 was previously submitted with Plan Control No.: S-7363, a Supplemental Exploration Plan for East Breaks Block 646. The data was provided within the geohazard reports, “Geologic and Stratigraphic Assessment, Block 646 (OCS G-20725), East Breaks Area, Gu lf of Mexico” (GEMS Report No. 0607-1352).”

A Shallow Hazards Report for East Breaks Block 602 and 645, which also discussed East Breaks Block 646; was previously submitted with the In itial/Supplemental Exploration Plan for East Breaks Block 645 and 646, Plan Control No.: N-9591. The data was provided within the geohazards report, “ Geologic and Stratigraphic Assessment, Blocks 602 and 645, East Breaks Area, Gulf of Mexico” (GEMS Report No. 0409-1634). ” The report was an extension to the previous project submitted with Plan Control No.: S-7363.

### (f) Shallow Hazards Assessment

A Site Clearance Letter for the Proposed We llsite East Breaks Block 646, Location EE is included with this EP submittal and enclosed as Attachment C-4. East Breaks Block 646, Location EEE is approximately 100' East of Ea st Breaks Block 646, Locati on EE and is therefore referencing the same Site Clearance Letter since within a 500' radius.

(g) High-resolution Seismic Lines

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

(h) Stratigraphic Column

A generalized stratigraphic colu mn depicting the wells from the seafloor to total depth was
included as Attachment C-6 in the Confidential EP version and has been omitted from this public copy of the EP

.

(i) Time Vs. Depth Tables

The proposed activities under this EP are not cons idered to be in areas where there is no well control. Therefore, a seismic travel time versus depth table is not required per NTL 2008-G04, extended by NTL BOEM 2013-G02.**10615 Shadow Wood Drive Suite 200**  **Houston, Texas 77043 (713) 468-1410 (o)**  **(713) 468-1438 (f)** www.gemsinc.com

**Geoscience Earth & Marine Services, Inc. ®** // 1 FORUM ENERGY TECHNOLOGIES, INC. **May 13, 2013 Project No. 0413-2227** 

**A nadarko Petroleum Corporation**  **1201 Lake Robbins Drive The Woodlands, TX 77380** 

**Attention: Mr. Charles Contrino**



### Site Clearance Letter Proposed Wellsite EE Block 646 (OCS G

**-** 20725) East Breaks Area, Gulf of Mexico

**Anadarko Petroleum Corporation (Anadarko) plans to drill an exploration well in Block 646 (OCS G-20725) of the East Breaks (EB) area, Gulf of Mexico. This letter addresses specific seafloor and subsurface**  **geologic and stratigraphic conditions to a depth of about 6,194 ft below the mudline (bml) at the Proposed Wellsite EB646-EE location. The following discussion is based on findings provided within the geohazard**  **reports “Geologic and Stratigraphic Assessment, Block 646 (OCS G-20725), East Breaks Area, Gulf of Mexico” (GEMS Report No. 0607-1352), and “Geologic and Stratigraphic Assessment, Blocks 602 and 645,**  **East Breaks Area, Gulf of Mexico” (GEMS Report No. 0409-1634). Anadarko provided the following coordinates:** 



### Proposed Wellsite EE

Spheroid & Datum: Clarke 1866, NAD27 Projection: UTM Zone 15 North, U.S. ft Line Reference Block Calls

EB 646
**X: 1,158,128 ft Latitude: 27o 21' 36.291" N**  **Inline 1114 1,808 ft FWL** 
**Y: 9,931,168 ft Longitude: 94o 29' 10.629" W**  **Crossline 2341 512 ft FNL** 

**Anadarko plans to drill this well using a dynamically positioned drilling vessel. Our assessment addresses the seafloor conditions within a 2,000 ft radius around the proposed well location.** 

Attachments

**The 1:12,000 scale maps accompanying this letter were extracted from the main report’s original maps and 3-D data volume. The maps and figures (listed below) are centered on the proposed well location.** 

**Map EB646-EE-1: Bathymetry Map Map EB646-EE-2: Seafloor Rendering**  **Map EB646-EE-3: Seafloor Amplitude Rendering Map EB646-EE-4: Geologic Features Map**  **Figure EB646-EE-1: Inline 1114 and Crossline 2341 Showing Conditions Beneath Proposed Wellsite EE Figure EB646-EE-2: Tophole Prognosis Chart, Proposed Wellsite EE, East Breaks Block 646**  **Figure EB646-EE-3: Side-Scan Sonar Mosaic in the Vicinity of Proposed Wellsite EE Figure EB 646-EE-4: Subbottom Profiler Line 805 Showing Near-Surface Conditions Beneath Proposed** 

**Wellsite EE Project No. 0413-2227** 

**Anadarko Petroleum Corporation**

**Geoscience Earth & Marine Services, Inc. ®** FORUM ENERGY TECHNOLOGIES, INC. NTL Requirements

**The following report complies with the Bureau of Notice to Lessees (NTL’s) 2008-**  **G04, will be required to follow NTL’s 2008**  **pre- and post- spud ROV visual inspection surveys (MMS, 2008b and**  **EB 646 is not considered archaeologically significant**  **requirements set forth in NTL 2005 However, pursuant to the Pre-**  **Seabed Disturbance Survey Mitigation issued by 2011)**  **, an archaeological assessment of the To comply with the pre-**  **seabed disturbance mitigation requirements, Anadarko elected to perform a high resolution geophysical survey in the area utilizing an autonomous underwater vehicle (AUV). C & C**  **Technologies, Inc. prepared an archaeological assessment using these data (C 2011).** 

Power Spectrum. **According to NTL 2008 shallow hazard assessments with approval from the BOEM, Gulf of Mexico Region. A power spectrum analysis**  **was conducted from the 3- D seismic data cube provided by**  **power spectrum curve (below) was generated within a 500 at the proposed wellsite location. We converted the amplitude vs. frequency spectrum, generated by th**  **software, to power vs. frequency by squaring the amplitude values as described by J. A. Coffeen, 1978.**

Power Spectrum Analysis Curve,

Man-Made Features

**Anadarko’s Nansen SPAR is located in the southern portion of EB 602, approximately 1.25 miles (6,575**  **northeast of the proposed wellsite (Maps EB646**  **several wells in the Nansen field and around the Nansen field (BOEM, 201**  **646 #SS007 and #SS008 that lie approximately 4,7**  **The following report complies with the Bureau of Ocean Energy Management (**  **BOEM G04,**  **2008-G05, and 2009-G40 (MMS, 2008a,b 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**

**spud ROV visual inspection surveys (MMS, 2008b and 2008c).**  **The Federal lease block 646 is not considered archaeologically significant**  **(NTL 2011-JOINT-G01, BOEM, 2011**  **requirements set forth in NTL 2005 -G07 (MMS, 2005) are not applicable**  **in terms of high Seabed Disturbance Survey Mitigation issued by**  **BOEMRE (BOEMRE, , an archaeological assessment of the**  **site must be performed prior to any bottom disturbing activities** 

**seabed disturbance mitigation requirements, Anadarko elected to perform a high resolution geophysical survey in the area utilizing an autonomous underwater vehicle (AUV). C & C**  **Technologies, Inc. prepared an archaeological assessment using these data (C & C Technologies Inc.,** 

**According to NTL 2008 -G05 (MMS, 2008a), 3-**  **D seismic reflection data may be used for shallow hazard assessments with approval from the BOEM, Gulf of Mexico Region. A power spectrum analysis**  **D seismic data cube provided by Anadarko**  **to illustrate the data parameters. The power spectrum curve (below) was generated within a 500** 

**- ft radius of the intersection of the inline and crossline**  **at the proposed wellsite location. We converted the amplitude vs. frequency spectrum, generated by th software, to power vs. frequency by squaring the amplitude values as described by J. A. Coffeen, 1978.** 

Power Spectrum Analysis Curve, EB 646, Proposed Wellsite EE

**is located in the southern portion of EB 602, approximately 1.25 miles (6,575 (Maps EB646**  **-EE-1 through EE-4). The SPAR is the surface location to**  **several wells in the Nansen field and serves as the hub for several i**  **nfield and export pipelines within and around the Nansen field (BOEM, 201**  **3). The closest wells to the proposed wellsite are the Anadarko EB**  **approximately 4,7 60 ft and 4,890 ft, respectively,**  **to the southeast. //**  **May 13, 2013**

// 2 **BOEM , formerly MMS)**  **and 2010). The operator G06 with respect to an ROV monitoring survey as well as**  **The Federal lease block BOEM, 2011**  **); therefore, in terms of high**  **-probability. BOEMRE (BOEMRE,**  **must be performed prior to any bottom disturbing activities**

**. seabed disturbance mitigation requirements, Anadarko elected to perform a high** 

**** **resolution geophysical survey in the area utilizing an autonomous underwater vehicle (AUV). C & C & C Technologies Inc.,** 

**D seismic reflection data may be used for shallow hazard assessments with approval from the BOEM, Gulf of Mexico Region. A power spectrum analysis**  **to illustrate the data parameters. The ft radius of the intersection of the inline and crossline**  **at the proposed wellsite location. We converted the amplitude vs. frequency spectrum, generated by th e SMT**  **software, to power vs. frequency by squaring the amplitude values as described by J. A. Coffeen, 1978.**

**is located in the southern portion of EB 602, approximately 1.25 miles (6,575 ft)**  **is the surface location to nfield and export pipelines within and** 

**are the Anadarko EB to the southeast.** **Project No. 0413-2227**

**Anadarko Petroleum Corporation //**  **May 13, 2013**

**Geoscience Earth & Marine Services, Inc. ®** // 3 FORUM ENERGY TECHNOLOGIES, INC. **The closest pipeline to the proposed wellsite is a Williams Field Services 12" oil export pipeline located approximately 0.22 miles (1,442 ft) to the southeast. A 12” gas export pipeline semi-parallels the oil**  **pipeline but lies about 500 ft further to the southeast or about 2,000 ft from the proposed wellsite. The pipelines approach the Nansen Spar in EB 602 from the southwest. These are the only pipelines that are**  **within 2,000 ft of the proposed wellsite. The Williams Field Services export lines and other nearby pipelines and umbilicals should not have any impact on drilling operations at this locations. The pipelines are visible**  **on the sonar data (Figure EB646-EE-3). In addition, anchor scars extending from previous wellsites and possible pipeline barges occur along the seafloor near the proposed EB 646-EE wellsite (Figure EB646-**  **EE-3).**
**Eleven military warning areas are located within the Gulf of Mexico. These areas represent regions where the U.S. Department of Defense conducts various testing and training operations. Lessees within military**  **warning areas are required to enter into an agreement with the appropriate command headquarters concerning the control of electromagnetic emissions and the use of boats and aircraft within the warning**  **area (NTL 2009-G06, MMS 2009). East Breaks Block 646 is within the active W-602 Military Warning Area. The U.S. Navy controls the airspace of W-602. Coordination of field operations with the Navy may be**  **necessary. The command headquarters information for W-602 is:**
**Strategic Command Wing 1, Fleet Area Reconnaissance 4; Operations Department Tinker Air Force Base**  **Oklahoma City, Oklahoma 73145-8704 Telephone: (405) 739-5700/4527** 

Wellsite Conditions

**The surface location is clear of any constraining geologic conditions within a 2,000 ft radius from the proposed wellsite.** 

Water Depth and Seafloor Conditions. **The water depth at the proposed location is approximately -3,637 ft (Map EB646-EE-1). The seafloor dips slightly to the northwest at approximately 1.7**  ° **(3.0%). The proposed wellsite is in a shallow low within a northeast-southwest trending fault system (Map EB646-EE-2).**  **The seafloor at the proposed wellsite is irregular. The near-surface sediments are expected to be normally consolidated, soft clays forming a drape over the area (Figure EB646-EE-4).** 

Deepwater Benthic Communities. **The Seafloor Amplitude Rendering (Map EB646-EE-3) shows normal or ambient amplitudes along the seabed near the proposed wellsite. Subbottom profiler data, however,**  **show areas of near-surface gassy sediments approximately 1,350 ft to the southwest and 1,700-1,900 ft to the northwest (Map EB646-EE-4). Sonar data shows the seabed above the gassy zones to the northwest,** **in general, to consist of normal or ambient backscatter (Figure EB646-EE-3). No patches of high backscatter or other indications of benthic communities occur along the seabed northwest of the proposed**  **location.**
**Patches of high-backscatter seafloor returns occur above the buried zone of gassy sediments southwest of the proposed location. Benthic community development is possible within these zones. The patches**  **located approximately 1,600 to 1,900 ft from the proposed location show an increase in backscatter but generally lack an increase in bottom roughness. Minor community development is possible within these**  **patches. Just over 2,000 ft southwest of the proposed location within the zone of gassy sediments there is a patch on the seafloor that exhibits both increase in backscatter and an increase in bottom roughness**  **(Figure EB646-EE-3). The increase in roughness likely indicates authigenic carbonates and increases the potential for high-density chemosynthetic and other benthic communities.** 
Stratigraphy. **The stratigraphy at the proposed well location is illustrated on Figures EB646-EE-1, EB646- EE-2 and EB646-EE-4.** 
**The subbottom profiler data show approximately 250 ft of well-stratified, hemipelagic, clay-rich, sediments beneath the seafloor at the proposed location (Figure EB646-EE-4). The nearly transparent drape of**  **presumably very soft, high water content pelagic clays is approximately 12.5 ft thick at the proposed location. The soils beneath the drape will gradually increase in strength and decrease in water content with**  **depth. Project No. 0413-2227** 

**Anadarko Petroleum Corporation //**  **May 13, 2013**

**Geoscience Earth & Marine Services, Inc. ®** // 4 FORUM ENERGY TECHNOLOGIES, INC. **The Tophole Prognosis Chart (Figure EB646-EE-2) shows the inline annotated with calculated depths to the various horizons and predicted lithology of the sequences, along with their potential for shallow water flow**  **and shallow gas. In general, the sediments between the seafloor and the limit of investigation (about 6,194 ft bml) consist of hemipelagic clays and bedded clay-rich turbidites, interbedded with mass-transport**  **deposits. Sands may occur within channel and turbidite deposits located between 657 ft and 1,309 ft bml, and within slope-fan deposits located between 1,309 ft and 1,870 ft bml. The deeper unit may correspond**  **to the regional slope-fan sequence labeled the GB Orange Unit. Hemipelagic clays, muddy turbidites, and clay-rich gravity flow deposits dominate the stratigraphy below Horizon 40 (1,870 ft bml) to the limit of**  **investigation (6,194 ft bml). Potential sand-prone turbidite deposits may also be encountered between 2,498 ft and 4,033 ft bml.** 

Faults. **The near-surface section shows numerous faults (Figure EB646-EE-4). The proposed location occurs between two buried, northwest-southeast trending faults. The wellbore will be very close to the top**  **of the southern buried fault. The top of this fault will be ~65 ft bml. This fault is downthrown away from the proposed location. The top of the other fault is ~125 ft to the north. The well bore will intersect the fault**  **plane at approximately 230 ft bml. These faults are minor offsets and are not resolved on the 3-D data.**

**The proposed wellsite will penetrate several faults at depth. Three faults to be intersected are seafloor faults and will be encountered at approximately 1,077 ft, 1,568 ft, and 2,707 ft bml (Figures EB646-EE-1**  **and EB646-EE-2). A fourth fault to be penetrated is a buried fault and will be encountered at approximately 3,758 ft bml. All four faults are downthrown to the east and southeast. In general, the faults show**  **"brightening" of amplitudes within the subsurface, indicating that gas/fluid is potentially migrating along the fault. We recommend using caution while drilling through these faults.** 

Shallow Gas and Shallow Water Flow. **Shallow gas is not expected at this proposed wellsite (Figure EB 646-EE-2). The potential for shallow water flow at this well location is moderate within most of**  **the stratigraphic intervals between Horizon 20 and Horizon 40 (Figure EB 646-EE-2).**

Shallow Gas

. **The well path will not penetrate any high-amplitude events within the shallow tophole section (Map EB646-EE-4). The closest high-amplitude event is located approximately 380 ft northeast of**  **the proposed site. This amplitude anomaly occurs within slope-fan deposits within the Horizon 30 to Horizon 40 sequence (1,309 ft to 1,870 ft bml). Other high-amplitude events are also within the Horizon 30**  **to Horizon 40 interval as well as in the intervals immediate above and below, but these events are farther from the proposed wellsite. These amplitude anomalies suggest an increase in the amount of shallow gas**  **within likely sand-rich layers in that interval. There is a moderate potential for encountering shallow gas from 990 ft to 1,870 ft bml.** 
**There is a low potential of encountering shallow gas within thin sands located below 2,498 ft bml to the limit of investigation (6,194 ft bml). The remaining the sequences beneath the proposed wellsite have a**  **negligible potential for encountering shallow gas.**

Shallow Water Flow **. There is a moderate potential for shallow water flow within the sand-prone intervals between 657 ft and 1,870 ft bml (Figure EB646-EE-2). These sequences contain interbedded**  **turbidites and mass-transport deposits, with possible sand seams. The regional, slope fan sequence labeled the GB Orange Unit may correlate with the stratigraphic sequence between 1,309 ft and 1,870 ft**  **bml. Thin, bedded turbidite sands and discontinuous sand seams may occur within this unit. The existing wells within and adjacent to EB 646 did not report shallow water flow from the mapped Orange Unit interval;**  **however, water flow has been reported in the 657 ft to 1,309 ft interval at the Maxus EB 645 #001 well. We recommend designing your casing program to take into account the potential for shallow water flow at these**  **intervals.**
**The potential for shallow water flow is low between 1,870 ft bml and the limit of investigation at 6,194 ft bml, as the well bore may encounter thin sand seams within this interval. The remaining stratigraphic sequences**  **at the proposed wellsite have a negligible potential for encountering shallow water flow.**

Closing

**The Proposed Wellsite EE in East Breaks Block 646 appears suitable for exploration drilling operations. However, there is some potential for deepwater benthic communities approximately 2,000 ft southwest of**  **the location. In addition, caution is advised while drilling through the potentially sand-prone intervals Project No. 0413-2227** 

**Anadarko Petroleum Corporation //**  **May 13, 2013**

**Geoscience Earth & Marine Services, Inc. ®** // 5 FORUM ENERGY TECHNOLOGIES, INC. **between 657 ft and 1,870 ft bml. The potential for shallow water flow and shallow gas is increased in these intervals.** 
**Caution is also advised while drilling through the seafloor and buried faults. One minor fault will be intersected within ~230 ft bml. The deeper, major faults, in general, show "brightening" of amplitudes along**  **the fault plane, suggesting the presence of migrating gas/fluid.**

**We appreciate the opportunity to be of service to Anadarko Petroleum Corporation and look forward to working closely with you on other projects.** 

**Sincerely,**

GEOSCIENCE EARTH & MARINE SERVICES, INC. ®

**John Hoffman Daniel Lanier**  **Senior Geologist Vice President - Geoscience** 

**Thomas W. Neurauter, Ph. D. Senior Marine Geologist** 

Attachments: **(4 Maps and 4 Figures)** Distribution: **Mr. Charles Contrino, Anadarko Petroleum Corporation, The Woodlands, TX (4 Copies)**

References:

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

**Bureau of Ocean Energy Management, 2011, Notice to lessees and operators (NTL) of federal oil and gas leases and pipeline right-of-way (ROW) holders on the outer continental shelf (OCS); Revisions to the list of OCS lease blocks**  **requiring archaeological resource surveys and reports: U. S. Department of the Interior, Bureau of Ocean Energy, Bureau of Safety and Environmental Enforcement, Gulf of Mexico OCS Region (GOMR), NTL 2011-JOINT-G01.**  **Effective Date December 29, 2011.**

**Bureau of Ocean Energy Management, 2013, ASCII data files, published on the BOEM Gulf of Mexico Region homepage, <http://www.gomr.boem.gov/homepg/pubinfo/freeasci/freedesc.html>, accessed May, 2013.** 

**C & C Technologies, Inc., 2011, Archaeological Assessment Report; Nansen, Eriksson, and Mawson Exploration Prospect, Blocks 602 (OCS-G-14205), 645 (OCS-G-32822), and 646 (OCS-G-20725), East Breaks Area, Gulf of**  **Mexico, Project No. 110397.**

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

**Geoscience Earth & Marine Services, Inc.® (GEMS), 2007, Geologic and stratigraphic assessment, block 646 (OCS G 20725), East Breaks Area, Gulf of Mexico, Project No. 0607-1352.** 

**Geoscience Earth & Marine Services, Inc.® (GEMS), 2009, Geologic and stratigraphic assessment, blocks 602 and 645, East Breaks Area, Gulf of Mexico, Project No. 0409-1634.** 

**Minerals Management Service, 2005, Notice to lessees and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, Archaeological resource surveys**  **and reports: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2005-G07.**

**Minerals Management Service, 2008a, Notice to lessees and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, shallow hazards requirements:**  **U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G05.**

**Minerals Management Service, 2008b, Notice to lessees and operators of federal oil, gas, and sulphur leases and pipeline right-of-way holders in the outer continental shelf, Gulf of Mexico OCS region, information requirements for** **Project No. 0413-2227**

**Anadarko Petroleum Corporation //**  **May 13, 2013**

**Geoscience Earth & Marine Services, Inc. ®** // 6 FORUM ENERGY TECHNOLOGIES, INC. **exploration plans and development operations coordination documents: U. S. Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G04.** 

**Minerals Management Service, 2008c, Notice to lessees and operators of federal oil, gas, and sulphur leases in the outer continental shelf, Gulf of Mexico OCS region; remotely operated vehicle surveys in deepwater, U. S. Department**  **of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2008-G06.**

**Minerals Management Service, 2009, Notice to lessees and operators of federal oil and gas leases and pipeline right-of way holders on the outer continental shelf, Gulf of Mexico OCS region, Military Warning and Water Test Areas: U. S.**  **Department of the Interior, Minerals Management Service, Gulf of Mexico, NTL 2009-G06. Effective Date April 22, 2009.** 

**Minerals Management Service, 2010, Notice to lessees and operators of federal oil and gas leases in the outer continental shelf, Gulf of Mexico OCS region, deepwater benthic communities: U. S. Department of the Interior,**  **Minerals Management Service, Gulf of Mexico, NTL 2009-G40. Effective Date January 27, 2010.**1.400

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NORTH SOUTH WEST EAST Filename: 132227_ill_EB646-EE-1.cdr Project No. 0413-2227

INLINE 1114



### Illustration EB646-EE-1. Inline 1114 and Crossline 2341 Showing Conditions Beneath Proposed Wellsite EE CROSSLINE 2341 HORIZON 10 SEAFLOOR

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3.000

3.200

3.400 Horizontal Distance (ft): WATER FLOW AND GAS POTENTIAL Shallow Water Flow and Gas Potential HIGH

0 1 2 3 0 = NEGLIGIBLE 1 = LOW 2 = MODERATE 3 = HIGH NEGLIGIBLE

Horizon Lithology/Stratigraphy



### Illustration EB646-EE-2. Tophole Prognosis Chart, Proposed Wellsite EE, East Breaks Block 646 Potential Drilling Constraints Filename: 132227_ill_EB646-EE-2.cdr Project No. 0413-2227

Water Flow Gas 3-D Seismic Section Through Proposed Wellsite EE X = 1,158,128 FT; Y = 9,931,168 FT Inline 1114 at Crossline 2341 

## W E

Horizon TWT (sec, bsl) Depth (ft, bml) Depth (ft, bsl)

INLINE 1114 SEAFLOOR

HORIZON 10

HORIZON 20

HORIZON 40 1.492

1.630

1.716

1.927 401

990 -3,634

-4,035

-4,642 PROPOSED WELLSITE EE

HORIZON 30 1.825

2,498 1,568 1,077

2,707

3,758 -6,132 -5,202 -4,711

-6,341

-7,392 Stratified hemipelagic silts and clays with thin, muddy turbidites. Thin sand seams possible. There is a negligible potential for high-density chemosynthetic communities within 1,500 ft of the proposed location.

INTERFACE 1

INTERFACE 2 FAULT FAULT

FAULT

FAULT

INTERFACE 3

LIMIT OF INVESTIGATION 2.101

2.289 2.008 1.853

2.350

2.648

3.300 -4,291

-4,943

-5,504

-9,828 657

1,309

1,870

6,194 2.724 -7,667 4,033 Interbedded turbidites and channel deposits. Clay-rich, contains silts and possible sand seams.

Slope-fan turbidite deposits interbedded with clay-rich masstransport deposits. Potential sand seams likely. Unit may correlate to regional GB Orange Unit.

Predominantly clay-rich turbidity and gravity flow deposits interbedded with layered hemipelagic clays.

Potential sand-prone turbidite deposits from 2,498 ft to 4,033 ft bml. Negligible potential for shallow water flow and shallow gas.

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

Low potential for overpressured sands. Low potential for encountering shallow gas below 2,498 ft bml to the limit of investigation. Moderate potential for overpressured sands and shallow gas.

RELATIVE AMPLITUDE

12998 -12998TWO-WAY TIME TRAVEL (SEC) Predominantly clay-rich mass-transport deposits.

Slope-fan turbidite deposits interbedded with clay-rich masstransport deposits. Potential sand seams likely. Negligible potential for shallow gas and overpressured sands.

### SECTION D HYDROGEN SULFIDE INFORMATION

Discussions regarding geologic in formation are consider ed proprietary and ha ve been omitted from this public copy of the EP. Anadarko requests that the area be classified as a “zone where the
absence of H 2 

### S has been confirmed”, pursu ant to 30 CFR 250.67(c).

### SECTION E BIOLOGICAL, PHYSICAL, AND SO CIOECONOMIC INFORMATION

(a) Chemosynthetic Communities Report

The seafloor disturbing activities pr oposed in this plan are in approximately 3,637' of water. The wells will be drilled with a DP drillship or DP semi-submersible.

Maps

A map prepared using 3-D seismic data to depi ct bathymetry, seafloor and shallow geological features, and surface locations of the proposed wells is included in Section A.

Analysis

Features or areas that could support high-dens ity chemosynthetic communities are not located within 2,000' of each proposed muds and cuttings discharge location.

Features or areas that could support high-dens ity chemosynthetic communities are not located within 250' of any seafloor disturbances.

(b) Topographic Features Map

The proposed activitie s are not within 1,000 ' of a no-activity zone or within the 3-mile radius zone of an identified topographic feature. Th erefore, no map is required per NTL 2008-G04, extended by NTL BOEM 2013-G02.

(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 2008-G04, extended by NTL BOEM 2013-G02, is not applicable.

(d) Live Bottoms (Pinnacle Trend) Map

The activities proposed in this plan are not within 200' of any pinnacle trend feature with vertical relief equal to or greater than 8'. Therefore, no map is required per NTL 2008-G04, extended by
NTL BOEM 2013-G02.

(e) Live Bottoms (Low Relief) Map

The activities proposed in this plan are not with in 100' of any live bottom low relief features. Therefore, no map is required per NTL 2008-G04, extended by NTL BOEM 2013-G02.

### (f) Potentially Sensitive Biological Features

The activities proposed in this pl an are not within 200' of any potentially sensitive biological features. Therefore, no map is requir ed per NTL 2008-G04, extended by NTL BOEM 2013-
G02.

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

East Breaks Blocks 646 is located within Deepwate r Grid Area 4. This grid is considered to have “inadequate ROV survey coverage”, and, therefore, under the guidance set out in NTL 2008-G06, a Remotely Operated Vehicle Mon itoring Survey Plan may be required.

Pursuant to NTL 2008-G06, operators may be re quired to conduct remotely operated vehicle (ROV) surveys during the propo sed operations for the purpose of biological and physical observations.

Anadarko is familiar with the ROV survey and reporting provisions of NTL 2008-G06; and if required, will conduct a survey.

Anadarko will utilize ROV equipped with video imaging capabilities. The survey pattern will consist of six transects centered on the well lo cation with tracks extending approximately 100 meters away from the well on bearings of 30 degrees, 90 degrees, 150 degrees, 210 degrees, 270 degrees and 330 degrees. The seafloor will be videotaped continuously along each track.

Anadarko will make biological and physical observa tions as described in the subject NTL and Form BOEM-141 prior to comm encing operations and prior to moving off location. The observations will be documented using Form BOEM-141, or a facsimile and submitted along with videotapes, and any other imagery obtain ed, to the BOEM/BSEE within 60 days after completion of the final ROV survey.

(h) Threatened and Endangered Species Information

Under Section 7 of the Endangered Species Act (ESA) all federal ag encies must ensure that any actions they authorize, fund, or carry out are not li kely to jeopardize the continued existence of a listed species, or destroy or adversely modify its designated critical habitat.

In accordance with the 30 CFR 550, Subpart B, effective May 14, 2007, and further outlined in Notice to Lessees (NTL) 2008-G04 (extended by NTL BOEM 2013-G02), le ssees/operators are required to address site-specific information on the presence of federally listed threatened or endangered species and critical habitat designat ed under the ESA and marine mammals protected under the Marine Mammal Protection Act (MMPA) in the area of proposes activities under this plan.

### Currently there are no designated critical habitats for the listed species in the Gulf of Mexico Outer Continental Shelf; however, it is possible th at one or more of thes e species could be seen in the area of our operations. The following table reflects the Federally-listed endangered and threatened species in the lease ar ea 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

Florida manatee Trichechus manatus latirostris E -- X Florida ( Peninsular ) Blue whale B alaenoptera musculus E X a

-- None Fin whale B alaeno p tera p h y salus 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 Dermochel y s 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 ) Terrestrial Mammals Beach mice (Alabama, Choctawhatchee, Perdido Ke y , 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

East Breaks Blocks 646 is not in an area designat ed as an area of high archaeological potential and, as such, as such, an Archaeological Repor t is not required per NTL 2008-G04, extended by extended by NTL BOEM 2013-G02. However an “A rchaeological Assessmen t Report” prepared by C & C Technologies Survey Services (Proj ect #110397) was previously submitted with the Initial/Supplemental EP, Plan Control No.: N-9591. The survey included portions of East Breaks Block 601/602/645/646/689/690.

### (j) Air and Water Qu ality Information

This EP does not propose activities for which the State of Florida is an affect ed State. Therefore, the discussion required per NTL 2008-G04, extended by NTL BOEM 2013-G02, is not applicable to this EP.

(k) Socioeconomic Information

The activities proposed in this plan are not loca ted offshore Florida. Therefore, socioeconomic information required per NTL 2008-G04, extended by NTL BOEM 2013-G02, is not applicable
to this EP.

### SECTION 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.

(a) Projected Generated Wastes

Type of Waste Composition Projected Amount Treatment/Storage/Disposal Synthetic-based drilling
fluids Synthetic-based drilling muds 12,500 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 (Baroid or MI.) Cuttings wetted with synthetic-based muds Cuttings coated with synthetic drilling muds/fluids, including drilled out

cement. 2,000 bbls/well Treated and discharged overboard. *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil still
remains. Water-based drilling fluids Water-based drilling muds (NaCl saturated, seawater, freshwater, barite) 7,000 bbls/well Discharge overboard or at seafloor

Cuttings wetted with water-based fluids Cuttings coated with water-based drilling muds/fluids 1,600 bbls/well Discharge overboard or at seafloor

Chemical product waste (well treatment fluids) Ethylene glycol
Methanol 100 bbls/month 25 bbls/month Transport to shore in DOT approved containers to Fourchon, Louisiana for pick up. Completion Fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base. Non-pollutant completion fluids Low density uninhibited completion brines 5,000 bbls/well Discharge overboard

Workover fluids Brine, spent acid, prop sand, debris 3,000 bbls/well Transport to shore in DOT approved containers to Fourchon, Louisiana and on to Newpark Base. Trash and debris Refuse generated during operations 350 bbls total Transport to shore in disposal bags by vessel to shorebase for pickup by municipal operations. *Sanitary Wastes Treated human body

waste 1,050,000 gals total Chlorinate and discharge overboard

*Domestic Waste Gray water 1,050,000 gals total Chlorinate and discharge overboard Deck drainage Platform washings and rainwater 735,000 bbls total Treat for oil and grease and discharge overboard
Produced water N/A N/A N/A
Desalinization Unit Seawater 73,500 bbls total Discharge overboard
Wash water Drill water (fresh) 10,500 bbls total Discharge overboard Blowout preventer fluid Blend (3% Stack Magic & Filtered Fresh Water) 27,750 gals total Discharge at seafloor

Ballast water Seawater 47,650 m3/year Discharge overboardCont. Type of Waste Composition Projected Amount Treatment/Storage/Disposal Bilge water Seawater 66,570 bbls total Discharge overboard through 15 ppm equipment
Excess cement at the seafloor Nitrified cement slurry 400 bbls/well Discharge at seafloor

Fire water Seawater 137,142 bb ls/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 752.5 bbls total Transport in DOT approved containers to shore for recycling

(b) Projected Ocean Discharges

Type of Waste Total Amount to be Discharged Discharge Rate Discharge Method

*Sanitary Wastes 1,050,000 gals 25 gals per person daily Chlorinate and discharge overboard *Domestic waste 1,050,000 gals 25 gals per person daily Chlorinate and discharge overboard Deck drainage 735,000 bbls 3,500 bbls/day Treat for oil and grease and discharge Blowout preventer fluid 27,750 gals 925 gals/week/well Vents on weekly basis Discharge at seafloor

Desalinization Unit 73,500 bbls 350 bbls/day Discharge overboard
Wash water 10,500 bbls 50 bbls/day Discharge overboard

Ballast water As needed Not continuous Discharge overboard Bilge water 66,570 bbls 317 bbls/day Discharge overboard through 15 ppm equipment
Excess cement at the
seafloor 800 bbls 20 bbls/min Discharge at seafloor

Fire water 28,799,820 bbls 137,142 bbls/day Discharge overboard Cooling water 28,799,820 bbls 137,142 bbls/day Discharge overboard Cuttings wetted with water-based fluids 3,200 bbls 1,000 bbls/hr max Discharge overboard or at seafloor

Water-based drilling
fluids 22,000 bbls** 1,000 bbls/hr max Discharge overboard or at seafloor

Cuttings wetted with synthetic-based fluids 4,000 bbls 49 bbls/day max at largest hole section *** Treated and discharge overboard *Note, an estimated 5-10% of cuttings may be transported to shore in tanks and/or cutting boxes and on to the base/transfer station if oil still remains

. Non-pollutant completion fluids 10,000 bbls 100 bbls/hour Discharge overboard

*The rig is designed for maximum personnel capacity of 200 people. The discharge rates are based off of maximum personnel capa city but will generally not have this many personnel onboard during drilling and/or completion operations.

* *The volume ordered out will be an estimated 7,000 bbls/well of mud. Once on location this volume will be cut back and mixed w ith seawater to different desired mud weights which will increase the volume that is discharged at the seafloor. The estimated volume that will be disch arged at the seafloor will be approximately 22,000 bbls/well. ***The rate for cuttings wetted with synthetic-based fluids varies depending on the hole section and the stage of the actual dr illing process. Therefore the estimated maximum daily average for the largest hole section has been denoted, as smaller hole sections will have a decreased r ate. 

### (c) Modeling Report

The proposed activities under this plan do not meet the U.S. Environmental Protection Agency requirements for an individual NPDES permit. Therefore, modeling report requirements per NTL 2008-G04, extended by NTL BOEM 2013-G 02, is not applicable to this EP.

### SECTION 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 H 2 S at concentrations greater than 20 parts per million (ppm)? No Do you propose to flare or vent natural gas for more than 48 continuous hours from any proposed well? No

Do you propose to burn produced hydrocarbon liquids? No



### (b) Emissions Worksheets

Air emissions worksheets have been prepared using a DP Drillship, DP Semi-submersible, and a Semi-Submersible drilling rig. Air emissions worksheets are available upon request. Per NTL 2008-G04 (extended by NTL BOEM 2013- G02), if an operator “answers no to all of the above screening questions from the appropriate table, provide”:

(1) “Summary information regarding the peak year emissions that will be generated by and associated with your Plan Emissions and Complex Total Emissi ons. This information is compiled on the summary form of the two sets of worksheets, and you can subm it either these summary forms or the format below.
You do not need to include the entire set of worksheets.”



### (c) Summary Information

EB 646: If drilled with a DP Drillship

Air Pollutant Plan Emission Amounts 1 (tons) 2015 Calculated Exemption Amounts 2 (tons) Calculated Complex Total Emission Amounts 3 (tons) 2018 Particulate matter (PM) 55.32 3,962.70 92.20 Sulphur dioxide (SO 2 ) 253.79 3,962.70 422.99 Nitrogen oxides (NO
x ) 1,901.72 3,962.70 3,169.53 Volatile organic compounds (VOC) 57.05 3,962.70 95.09 Carbon monoxide (CO) 414.92 82,257.76 691.53

EB 646: If drilled with a DP Semi-submersible

Air Pollutant Plan Emission Amounts 1 (tons) 2015 Calculated Exemption Amounts 2 (tons) Calculated Complex Total Emission Amounts 3 (tons) 2018 Particulate matter (PM) 54.79 3,962.70 91.32 Sulphur dioxide (SO 2 ) 251.35 3,962.70 418.91 Nitrogen oxides (NO
x ) 1,883.40 3,962.70 3,139.00 Volatile organic compounds (VOC) 56.50 3,962.70 94.17 Carbon monoxide (CO) 410.92 82,257.76 684.87 *Plan emissions amounts (tons) are based on 105 days in 2015. **Calculated complex total emission amount s (tons) are based on 175 days in 2018.Proposed Activity Start Date End Date No. of Days

Drill and complete Location EE (E B 646) 10/1/2013 1/14/2014 105

Drill and complete Location EEE (E B 646) 3/27/2015 7/10/2015 105



### Air emissions from undrilled well locations unde r previously approved pl ans (Plan Control No.: S-7569, S-7575 and N-9591) are bei ng carried forward in the following table to reflect
Anadarko’s current estimated dr illing schedule. No revisions are being requested to the previously approved well locations under this plan:

Proposed Activity Start Date End Date No. of Days

The following “Deep Nansen” proposed well locati ons are mentioned below for reference only:

Drill and complete Location II (EB 645)–Plan Control No .: S-7569 previously approved 7/8/2013 12/30/2013 175

Drill and complete Location CC (EB 689)–Plan Control No.: S-7575 previously approved 12/31/2013 6/24/2014 175

Drill and complete Location JJ (EB 690)–Plan Control No .: S-7575 previously approved 6/25/2014 12/17/2014 175

Drill and complete Location GG (EB 645)–Plan Control No.: S-7575 previously approved 12/18/2014 6/11/2015 175

Drill and complete Location GG (EB 689)–Plan Control No.: S-7575 previously approved 6/12/2015 12/4/2015 175

Drill and complete Location AA (EB 645)–Plan Control No : N-9591 previously approved 4/22/2016 10/14/2016 175

Drill and complete Location FF (EB 646)–Plan Control No : N-9591 previously approved 10/15/2016 4/8/2017 175

Drill and complete Location FF (EB 690)–Plan Control No.: S-7575 previously approved 1/1/2017 6/25/2017 175

Drill and complete Location EE (EB 645)–Plan Control No : N-9591 previously approved 4/9/2017 10/1/2017 175

Drill and complete Location MM (EB 646)–Plan Control No : N-9591 previously approved 11/1/2018 6/25/2018 175



### The air emission calculations were calculated by:

Bridget O’Farrell Regulatory Analyst (832) 636-1694 Bridget.OFarrell-Vi llarreal@anadarko.com

### SECTION 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) last approved on April 17, 2013 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, respectivel y) in accordance with 30 CFR Part
254.

(ii) Spill Response Sites

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

### Galveston, Texas Harvey, Louisiana Houma, Louisiana Lake Charles, Louisiana Leeville, Louisiana Venice, Louisiana Galveston, Texas Harvey, Louisiana Fourchon, Louisiana Cameron, Louisiana Leeville, Louisiana Venice, Louisiana

(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 Marine Well Containment Company (MWCC), which provides access to containment response capabilities and incl udes subsea dispersant injection equipment.

### (iv) Worst-Case Scenario Determination

Category Regional OSRP EP
Type of Activity E xploratory Exploratory
Facility Location (area/block) GB 346 EB 646
Facility Designation* Location A* Location FF

Distance to Nearest Shor eline 118 Miles 118 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** 139,700 bopd ***
Type of Oil(s) Crude Crude
API Gravity 30.1 o 27.1 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 2010-N06 (256,700 bopd) and BOEM (321,108 bopd) calculations approved under EP Plan Control No.: N-9579. Anadarko elected to denote a higher volume in the Regional OSRP for planning purpos es to demonstrate equipment response capabilities pe r previous discussions with Rusty Wright. *** The worst case discharge volume(s) proposed for East Breaks Block 646, Locations EE and EEE are lower than approved worst case discharge for the block, Location FF in Plan Control No.: N-9591. Location FF is the highest approved volume for the block

.



### Anadarko has determined that the worst-case scenario from the activities proposed in this Supplemental EP does not supersede the worst- case scenario for Garden Banks Block 346 as previously filed in the Regional OSRP.

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 last approved on April 17, 2013, 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 2010-N06. An Initial/Supplemental EP, Plan Control No.: N-9591 was previously approved for East Break s Block 645/646 on December 1, 2011; the plan included the information necessary to comply with NTL 2010-N06. Within the approved plan, the WCD volume for East Breaks Block 646 wa s determined to be 139,700 bopd for Location FF. (The approved WCD volume for East Br eaks Block 645 was 155,400 bopd for Location EE.)

The supplemental well locations requested within this plan do not exceed the previously approved WCD volume for East Breaks Block 646 (or East Breaks Block 645); therefore, no additional WCD volume assu mptions are provided within this plan.

### (c) Oil Spill Response Discussion

For the purpose of NEPA analys is, the largest spill volume or iginating from the proposed activity in East Breaks Block 646 would be an un controlled blowout during drilling operations at 139,700 barrels of crude with an API gravity of 27.1 o 

### . (As approved under Plan Control No.: N-9591.) Since the East Breaks Block 646 propos ed Location EE and EEE were less than the approved Location FF (Plan Control No.: N-9 591), the discussion is based on the highest approved volume for the block. A discussion of the blowout scenario from this proposed activity is included within this Supplementa l EP in accordance with NTL 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.

East Breaks Block 646 is located within Launch Area 21. According to the OSRAM, the trajectory indicates a 9% probability of potential impact to the shoreline in Matagorda County, Texas. The results are shown in Table H-2.

Matagorda County is identified as the most probable potential imp acted parish or county within the Gulf of Mexico for this operation. Matagorda County is located in Texas and includes Big Boggy National Wildlife Refuge (NWR), Aransa s NWR, San Bernard NWR, and Mad Island Wildlife Management Area (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 would be considered the largest potential spill volume at 139,700 barre ls of crude. An ADIOS weathering model was run based on a similar type of oil expected to be produced from this well. Based on this information, approximately 13% (18,161 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% (6,077 bbls) of the wo rst case discharge volume after natural evaporation/dispersion could potentially be burned.

Although unlikely in a spill las ting 30 days, potential shorelin e impact in Matagorda County, Texas could occur depending on environmental c onditions (wind, currents and temperature) at the time of an incident. Nearshore response ma y include the use of shoreline boom on beach areas, or protection/sorbent boom on vegetated ar eas. Surveillance and real time trajectories would aide in determining the most appropr iate strategies to respond to a spill.

Table H.3 provides an example of offshore and n earshore equipment, response times, and personnel to respond to a spill of 121,539 barrels, which is the estimated amount that would remain considering natural evaporation/dispersion at 24 hours. This amount could be further reduced through the applicat ion of aerial and subsea dispersants, provided su ch applications were approved.

Anadarko’s contingency plan for de aling with this worst-case di scharge would be to activate its Spill Management Team and equipment resour ces as described in it s Gulf of Mexico Regional Oil Spill Response Plan (OSRP) and provi de continuous support for the duration of the event. Response resources are activated and supplemented according to need. These resources would remain engaged in the response until the inci dent is deemed complete or until released by Unified Command.

### Anadarko is a member of the Marine Well Containment Company (MWCC), which provides access to containment response capabilities and incl udes 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 would 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 appropriate DP drillship, DP semi-submersible or semi-submersible drilling rig would be determined by marine surveyors. Operations and Unified Command would continue to assess the adequacy of respons e 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 aircra ft and two DC-3 aircrafts from Houma if needed, with surveillance aircraft and spo tter. Rotate aircraft, spraying the leading edge of the spill and working back to the source. Monitor/sample for effectiveness (USCG SMART Team). Truck additional disp ersants from CGA or MSRC stockpile, 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 51 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) coul d arrive on-scene between approximately 13.75-28.5 hours of the initial release. Thes e skimmers operate downstream of the HOSS barge and are used to recover pockets and streamers of oil that may move past the large stationary skimme r. FRUs have approximat ely 200 barrels of on-board storage. Approval will be requested to decan t water after gravity separation, through a hose forward of the skimmer, to optimize temporary storage capacity. Auto boom will
be utilized to concentrate oil so th at 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 could be commenced again. Safety would remain the first priority.

### 10. Prepare site-specific Waste Management Plan, Site Safety Plan, Decontamination Plans, Communications and Medical Plans.

11. If oil becomes a threat to any shoreline, 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 Wildlife 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

### 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 an Uncontrolled Blowout)

Calculations for an Uncontrolled Blowout: Block 646

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

ii. API Gravity 27.1  ̊

iii. EP Location Used for NTL 2010-N06 WCD for EB 646 (Plan Control No: N-9591) Location FF

iv. Largest Anticipated WCD Rate during blowout 139,700 bbls

v. WCD Total for Drilling Operations for EB 646 (> 10 miles from shore): 139,700 bblsTable 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 la nd segment as included in the Oil Spill Risk Analysis Model (OSRAM) for the Western Gulf of Mexico. This information can be found on the BSEE website using 3/10/30 day potential impact, as applicable. The results are listed below.

Area/Block/

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

3 days 10 days 30 days

East Breaks Block 646,
Location FF (Plan Control No.: N-9591)

Drilling

(118 miles from shore) G20725 Launch
Area 21

Western Planning

Area Cameron County, TX Willacy County, TX Kenedy County, TX Kleberg County, TX Nueces County, TX Aransas County, TX Calhoun County, TX Matagorda County, TX Brazoria County, TX Galveston County, TX Jefferson County, TX Cameron Parish, LA Vermilion Parish, LA Iberia Parish, LA Terrebonne Parish, LA --

--

--

--

--

--

--

--

--

--

--

--

--

--

-- --

--

--

--

--

-- 1
1

--

--

--

--

--

--

-- 2
1
4
3
3
4
5 9
3
5
2
5
1

--

--Table H-3WCD Scenario Drilling Activities – Based on an uncontrolled blowout (118 miles from shore)East Breaks Block 646, Location FF (Plan Control No.: N-9591)139,700 bbls of crude (initial volume)121,539 bbls (after evaporation/dispersion)API Gravity 27.1oOffshore Equipment from Spill Detection to Equipment Deployment Response Time: East Breaks Block 646, Location FF (Plan ControlNo.: N-9591)Offshore 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 Houma001111.503.5HOSS BargeOperatorsTugs43,000 4,000 183CGA/HarveySTARSVOOHarvey1244046151Texas ResponderTransrec 350 + OSRV4,620'44"Sea Sentry Boom3,300'67"LAMOR10,567 4,000 1114 crewMSRC/Galveston Galveston0222209.25112.25Gulf Coast ResponderTransrec 350 + OSRV5,280'44"Sea Sentry Boom2,640'67"LAMOR10,567 4,000 1114 crewMSRC/Lake Charles Lake Charles02222014.25117.25Deep Blue ResponderLFF 100 Brush + OSRV6,600'44"Sea Sentry Boom660'67"LAMOR18,086 4,000 1114 crewMSRC/Fourchon Fourchon02222019.2122.2FRUOperatorsUtility Boat4,251 200 161CGA/InglesideSTARSVOOIngleside0221212.75116.75FRUOperatorsUtility Boat4,251 200 161CGA/GalvestonSTARSVOOGalveston022129.75113.75FRUOperatorsUtility Boat4,251 200 161CGA/Lake CharlesSTARSVOOCameron.5221215.75119.75FRUOperatorsUtility Boat4,251 200 161CGA/Morgan CitySTARSVOOMorgan City.5221217121FRUOperatorsUtility Boat8,502 400 2122CGA/LeevilleSTARSVOOLeeville0221220124FRUOperatorsUtility Boat8,502 400 2122CGA/VeniceSTARSVOOVenice.5221224.5128.5Spill Team Area Responders (STARS) called out byMarine Spill Response Corporation (MSRC)Vessel of Opportunity=VOOEMS=Enterprise Marine ServicesOffshore 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 Boat4,251 100 161CGA/HarveySTARSVOOHarvey.5221222126Koseq Skimming Arms,1 setVessel w/ storage/hull17,83010,00021CGA/GalvestonVOOGalveston021129.75123.75MSRC 570 Offshore BargeTugs2 Crucial Disk 88/302,640'44"Sea Sentry II Boom22,244 56,900 1316 crewMSRC/GalvestonVOOGalveston 02222017.25120.25CTCo2603OperatorsTug-- 25,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo2604OperatorsTug-- 20,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo2605OperatorsTug-- 20,000 161EMS/AmeliaSTARSVOOAmelia0244037142CTCo 5001OperatorsTug-- 45,000 161EMS/AmeliaSTARSVOOAmelia024403714210,000' 42" Auto BoomVOO-- -- 2010 crewCGA/HarveySTARSHarvey.5212221265,000' 42" Auto BoomVOO-- -- 2010 crewCGA/Lake CharlesSTARSCameron.521215.75119.755,000' 42" Auto BoomVOO-- -- 2010 crewCGA/GalvestonSTARSGalveston02129.75113.752,500' 42" Auto BoomVOO-- -- 126 crewCGA/InglesideSTARSIngleside021212.75116.752,500' 42" Auto BoomVOO-- -- 126 crewCGA/PascagoulaSTARSPascagoula021227.75131.7522,400' 42" BoomVOO-- -- 8025 crewAMPOL/New Iberia New Iberia021216.5120.54,800' 42" BoomVOO-- -- 189 crewAMPOL/Harvey Harvey021222126Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/GalvestonPHI/GalvestonSTARSSpill SiteSpill SiteGalveston111.5111.5------1.51.53------2.52.54.5Total 160,553 194,600Nearshore Equipment from Spill Detection to Equipment Deployment Response Time:East Breaks Block 646, Location FF (Plan Control No.: N-9591)Nearshore 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 Houma001111.503.5Trinity SWSOperators21,500 249 14CGA/GalvestonSTARSGalveston02129.25113.25SWS EgmopolOperators3,000 100 13CGA/GalvestonSTARSGalveston02124.507.5SWS EgmopolOperators3,000 100 13CGA/Morgan CitySTARSMorgan City.52128011SWS MarcoOperators3,588 34 13CGA/VeniceSTARSVenice.52129.5012.5SWS MarcoOperators3,588 34 13CGA/LeevilleSTARSLeeville.52128.5011.5SWS MarcoOperators3,588 20 13CGA/Lake CharlesSTARSCameron.5212609R/V Grand BayOperators5,000 65 13CGA/VeniceSTARSVenice.522.54.7507.25R/V RW ArmstrongOperators5,000 65 13CGA/LeevilleSTARSLeeville.522.512.75015.25R/V Bastian BayOperators5,000 65 13CGA/Lake CharlesSTARSCameron.522.510.25012.75R/V Timbalier BayOperators5,000 65 13CGA/GalvestonSTARSGalveston022.5608.5CTCo 2606OperatorsTugs-- 20,000 161EMS/Amelia Amelia0244020125CTCo 2607OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125CTCo 2608OperatorsTugs-- 23,000 161EMS/Amelia Amelia0244020125CTCo 2609OperatorsTugs-- 23,000 161EMS/Amelia Amelia02440201252,000' Beach Boom-- -- 6 CGA/Galveston Galveston0 121.5 26.51,000' Beach Boom-- -- 4 CGA/InglesideIngleside0 123282,000' Beach Boom-- -- 6 CGA/Pascagoula Pascagoula 0 12 4 2 9Nearshore Equipment, cont.Owner/Location Initial StagingHours toStagingAreaTime toProcure(1)TimetoLoad Out(2)TravelTime(Staging/Spill)(3)TimetoDeploy(4)TotalEstimatedResponseTimeTypeDeratedCapacity(bbls)Storage(bbls)No. ofUnits/Persons10,000' 18" BoomVOO-- -- 104 crewOil Mop/New Iberia New Iberia0211731210,000' 18" BoomVOO-- -- 104 crewOil Mop/Houston Houston12112.531310,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Arthur Port Arthur02112.537.510,000' 18" BoomVOO-- -- 104 crewOil Mop/Houma Fourchon.5211631110,000' 18" BoomVOO-- -- 104 crewOil Mop/Port Allen Port Allen02116.25311.2520,000' 18" BoomVOO-- -- 208 crewOil Mop/Belle Chasse Venice.5211761515,000' 18" BoomVOO-- -- 146 crewOil Mop/Gretna Gretna02118414Wildlife Support Trailer-- -- 1/ 2 crew CGA/HarveyHarvey.5 12 1.5 3 7.5Bird Scare Cannons-- -- 2 CGA/VeniceVenice.5 122 27Bird Scare Cannons-- -- 1CGA/Galveston Galveston 0 1 2 1 2 6Bird Scare Cannons-- -- 1CGA/Ingleside Ingleside 0 1 2 2.5 2 7.5Bird Scare Cannons-- -- 2CGA/Harvey Harvey .5 1 2 1.5 2 6.5Bird Scare Cannons-- -- 2CGA/Lake Charles Cameron.5 12 3.5 2 8.5Bird Scare Cannons-- -- 2CGA/Pascagoula Pascagoula 0 1 2 4.5 2 9.5Spotter HeloSurveillance HeloHand Held Radios------------1130PHI/GalvestonPHI/GalvestonSTARSSpill SiteSpill SiteGalveston111.5111.5------1.51.53------2.52.54.5Total 58,264 89,797*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

### SECTION I Environmental Monitoring and Envi ronmental Mitigation Measures

(a) Monitoring

If required, Anadarko will monitor loop currents per NTL 2009-G02.

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

Additional measures to avoid, minimize, and mitigate environmental impacts is included
in Section N–Environmental Impact Analysis.

(b) Incidental Takes

Although marine mammals may be seen in th e 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 appl icable regulations in order to avoid or
minimize incidental takes of marine mammals and other species, including:

 Joint NTL 2012-G02 “Implementation of Seismic Survey Mitigation Measures and Protected Species Observer Program”

 BSEE NTL 2012-G01 “Marine Trash and De bris Awareness and Elimination”, and

 Joint NTL 2012-G01 “Vessel Strike Avoi dance and Injured/Dead Protected Species Reporting”

### SECTION J LEASE STIPULATIONS INFORMATION

Military Areas (Stipulation No. 2)

East Breaks Block 646 is lo cated within Military Warni ng Area W-602. Anadarko will
contact the Fleet Air Reconnais sance Squadron Four (VQ-4) in order to coordinate and control the electromagnetic emission s during these proposed operations.

VQ-4 Operations Department 7791 Mercury Road Tinker AFB, Oklahoma 73145-8704 Telephone: (405) 739-5702

This stipulation includes the term s and conditions associated with: (a) Hold and Save Harmless–Lessee assumes all risks of damage or injury to persons or property, which occur in, on, or above the OCS, to any persons or to any property of any person or persons who are agents, employees, or invitees of the lessee, its agents, independent contractor s, or subcontractors doing business with the lessee in connection w ith any activities being performed by the lessee in, on, or above the OCS, if such injury or dama ge to such person or property occurs by reason of the activities of any agency of the United States Government, its contractors or subcontractors, or any of its officers, agents or employees, being conducted as apart of, or in connection w ith, the programs a nd activities of the command headquarters (b) Electromagnetic Emissions–Lessee agrees to control its own electromagnetic emissions in accordance with requirements specified to prevent damage, unacceptable interference with Departme nt of Defense flight, testing or operational activities within the designated warning area. (c) Operational–Lessee shall enter into an agreement with the commander of the individual command headquarter upon util izing an individual designated warning area prior to commencing such traffic.

### SECTION 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 transpor ted via a supply vessel as follows:

a. Size of fuel supply vessel: 230 feet

b. Carrying capacity of fu el supply vessel: 336,227 gallons
c. Frequency that fuel supply vessel will visit the facilities: once per week

d. Routes the fuel supply vessel will use to travel between the onshore support base and proposed facility: 6 miles from Port Fourchon to the mouth of Bayou Lafourche, then approximately 286
miles to EB 646.



### (c) Drilling Fluids Transportation

The following estimates were prepared utilizin g Anadarko’s experience with similar drilling operations. Estimated quantities are reflected in the table below.



### Type of Material Quantity Being Transported Transportation Method Water-based drilling fluid (NaCl saturated, seawater, freshwater, barite) for Pump and Dump 13 gallon tote tanks (liquids) 40-63 sacks on pallet (sack chemicals) Supply boat

Synthetic-based drilling fluid (internal olefin, ester) 13 gallon tote tanks (liquids) 40-63 sacks on pallet (sack chemicals) Supply boat

Oil-based drilling fluid N/A N/A

* Estimate 7,000 bbls/well ** Estimate 12,500 bbls/well Note: The estimated amount of tote tanks and size of sacks may vary during drilling operations.

### (d) Solid and Liquid Wastes Transportation

Type of
Waste Composition Total Projected Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or muds Synthetic-based drilling muds 25,000 bbls
total 12,500 bbls/well

(119.047 bbls/day/well average) Re-use and/or transport to shore in
DOT approved containers. Waste - Port Fourchon, LA and on to Newpark Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer Station Port Arthur. USLL Galveston and Fourchon
Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Cuttings wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including
drilled out

cement 200-400 bbls
total 100-200 bbls/well*

(.95bbls/day/well1.9047 bbls/day/well average)

*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 disposal facility)
or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 700 bbls
total

175 bbls
total 100 bbls/month/well

25 bbls/month/well Transport to shore in
DOT approved
containers for pick up Chemwaste in Sulphur, LA and Veolia Port Arthur, TX or to Newpark,
Port Arthur as nonhazardous waste. Can be returned to vendor and/or
used at another facility; MEG is
solidified and disposed of in a
landfill.
Methanol is
incinerated or
used for fuels blending. Completion
fluids Brine, spent acid, prop sand,
debris 6,000 bbls
total 3,000 bbls/well

(28.571 bbls/day/well average) Transport to shore in
DOT approved
containers
and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer Station Port Arthur. USLL
Galveston and Fourchon Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job.
Used brine and spent acid is
transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand,
debris 6,000 bbls
total 3,000 bbls/well

(28.571 bbls/day/well average) 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 Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent acid is
transferred toTransfer Station Newpark's Processing & Transfer facility for injection.

Trash and
debris Refuse generated during operations 350 bbls
total 50 bbls/month/well 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 752.5 bbls
total 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up American Recovery Fourchon, LA Recycled



### *Total projected amount a ssumes 2 wells at 105 days/well **Rate per day is an estimated max.average and may vary during drilling operational phases. The total amount is rounded to nearest whole number.

(e) Vicinity Map

A vicinity map is included in this section as Attachment K-1.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 2

Figure 1. Location of East Breaks Block 646

.

### SECTION L ONSHORE SUPPORT FACILITIES INFORMATION

(a) General

Per NTL 2008-G04, extended by NTL BOEM 2013- G02, the following tables reflect the onshore facilities Anadarko will utilize to pr ovide supplies and service support for the activities proposed in th is Exploration Plan.

Name Primary Location Existing/New/Modified Anadarko Service Base Fourchon, 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.



### (b) Support Base Construction or Expansion

No onshore support base constr uction or expansion is pla nned for these activities. Therefore dredging or filling activities associated with construction or expansion of facilities will not be applicable.

(c) Support Base Construction or Expansion Timetable

Since no onshore support base construction or e xpansion is planned for these activities, a timetable for land acquisition and construc tion or expansion is not applicable.

(d) Waste Disposal

Disposed wastes describe those wastes generated by the proposed activity that are disposed of by means other than by release into the water of the GOM at the site where they are generated. These wastes can be di sposed of by offsite release, injection, encapsulation, or placement at either onshore or offshore permitted locations for the purposes of returning them back to the environment.Type of
Waste Composition Total Projected Amount Rate Transport
Method Name/Location of Facility Disposal
Method

Syntheticbased drilling
fluid or muds Synthetic-based drilling muds 25,000 bbls
total 12,500 bbls/well

(119.047 bbls/day/well average) Re-use and/or transport to shore in
DOT approved containers. Waste - Port Fourchon, LA and on to Newpark Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer Station Port Arthur. USLL
Galveston and Fourchon Transfer Station. If recycled, returned to vendor (Bariod or MI). Re-used and/or recycled; if can’t be reused and/or recycled the waste is disposed of at Newpark (injection disposal facility)
or USLL (landfarm).

Cuttings wetted withsyntheticbased muds Cuttings coated with synthetic drilling muds, including drilled

out cement 200-400 bbls
total 100-200 bbls/well*

(.95bbls/day/well1.9047 bbls/day/well average)

*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 disposal facility)
or USLL (landfarm).

Chemical product waste (well

treatment fluids) Ethylene glycol

Methanol 700 bbls
total

175 bbls
total 100 bbls/month/well

25 bbls/month/well 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 6,000 bbls
total 3,000 bbls/well

(28.571 bbls/day/well average) Transport to shore in
DOT approved
containers and/or vessel
tanks for pick up Sent to Port Fourchon, LA and on to Newpark
Fourchon Transfer Station #1 & #2. Newpark Transfer Station Morgan City. Newpark Transfer Station Port Arthur. USLL
Galveston and Fourchon Transfer Station Unused brine can
be returned to
vendor and/or
stored for use on another job. Used brine and spent
acid is
transferred to Newpark's Processing & Transfer facility for injection.
Workover
fluids Brine, spent acid, prop sand,
debris 6,000 bbls
total 3,000 bbls/well

(28.571 bbls/day/well average) 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'sProcessing & Transfer facility for injection.

Trash and
debris Refuse generated during operations 350 bbls
total 50 bbls/month/well 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 752.5 bbls
total 430 bbls/120 days/well Transport in
DOT approved
containers to
shore for pick up American Recovery Fourchon, LA Recycled



### *Total projected amount a ssumes 2 wells at 105 days/well **Rate per day is an estimated max.average and may vary during drilling operational phases. The total amount is rounded to nearest whole number.

### SECTION M COASTAL ZONE MANAGEM ENT ACT INFORMATION

No additional enforceable policies/Coastal Zone Management Act consistency certification statements are included within this Supplemental EP. Coastal Zone Management consistency was previously give n by Texas, Louisiana and Mississippi with Plan Control No.: N-9591 for the approved Initial/Supplemental EP for East Breaks Block 645/646. Alabama and Florid a are not affected states.

### SECTION N ENVIRONMENTAL IMPACT ANALYSIS

# Environmental Impact Analysis

SUPPLEMENTAL EX PLORATION PLAN Ericksson Prospect

East Breaks Block 646 (OCS -G 20725 )
Offshore Texas

March 2013



### Prepared for:

Bridget O’Farrell Regulatory Analyst Anadarko Petroleum Corporation
1201 Lake Robbins Drive
The Woodlands, Texas 77380

Telephone: (832) 636

- 1694



### Prepared by:

CSA Ocean Sciences Inc.
8502 SW Kansas Avenue

Stuart, Florida 34997 Telephone: (772) 219

- 3000East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page ii 

## Contents

Page



### Introduction

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

A. Impact

- Producing Factors

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

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

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

A.2 Physical Disturbance to the Seafloor

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

A.3 Air Pollutant Emissions

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

A.4 Effluent Discharges

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

A.5 Water Intake

................................................................................................ .................................................. 9
A.6 O nshore 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 (Endange red)

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

C.3.2 West Indian Manatee (Endangered)

............................................................................................... 34
C.3.3 Endangered Mysticete Whales

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

C.3.4 Non

- Endangered Marine Mammals (Protected)

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

C.3.5 Sea Turtles (Endangered/Threatened)

............................................................................................ 39
C.3.6 Piping Plover (Threatened)

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

C.3.7 Whooping Crane (Endangered)

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

C.3.8 Gulf Sturgeon (Threatened)

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

C.3.9 Smalltooth Sawfish (Endangered)

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

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

C.3.11 Elkhorn Coral (Endangered)

............................................................................................................ 47

C.4 Coastal and Marine Birds

............................................................................................................................. 47

C.4.1 Marine Birds

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

............................................................................................. 50

## Contents
(C ontinued)

Page

East Breaks Block 646 March 2013
Environmental Impact Analysis for Supplemental Exploration Plan Page iii C.5 Fisheries Resources

................................................................................................ ...................................... 52

C.5.1 Pelagic Communities and Ichthyoplankton

..................................................................................... 52

C.5.2 Essential Fish Habitat

...................................................................................................................... 54

C.6 Archaeological Resources

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

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

C.6.2 Prehistoric Archaeological Sites

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

C.7 Coastal Habitats and Protected Areas

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

C.8 Socioeconomic and Other Resources

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

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

C.8.2 Public Health and Safety

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

C.8.3 Employment and Infrastructure

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

C.8.4 Recreation and Tourism

.................................................................................................................. 66
C.8.5 Land Use

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

C.8.6 Other Marine Uses

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



### D. Environmental Hazards

......................................................................................... 68

D.1 Geologic Hazards

................................................................................................ ......................................... 68

D.2 Severe Weather

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

................................................................................................ ..................................... 68



### E. Alternatives

.......................................................................................................... 69

F. Mitigation Measures

............................................................................................. 69

G. Consultation

......................................................................................................... 69

H. Preparers

.............................................................................................................. 69

I. References

............................................................................................................. 69East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page iv 

## List of Tables

Table Page

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

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

2 Matrix of impact

- producing factors and affected environmental r esources

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

3 Conditional probabilities expressed as percent chance that an oil spill starting at Launch Point 5 will contact a certain parish, county, or coastlin e within 120 days (Modified from: BOEM, 2012b, Appendix C)

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

4 Benthic community data from stations near the lease area in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Adapted from: Wei, 2006; Rowe and Kennicutt, 2009)

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

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 conta cts after 120 days (From: BOEM, 2012b)

...................................................................................................................... 60



## List of Figures

Figure Page

1 Location of East Breaks Block 646

......................................................................................... 2

2 Bathymetric map of the lease area showing the proposed surface hole locations

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

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

........................ 43East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page v 

## Acronyms and Abbreviations

ADIOS 2 Automated Data Inquiry for Oil Spills 2
Anadarko Anadarko Petroleum Co rporation
bbl barrel

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 metha ne CO carbon monoxide

CO 2 carbon dioxide

CFR Code of Federal Regulations

CGA Clean Gulf Associates

DP dynamically positioned

EB East Breaks

EP Exploration Plan

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

ESA Endangered Species Act

FAD fish

- attracting device

FR Federal Register

FRV fast response vessel

GEMS Geoscience Earth & Marine Services, Inc.

GPS global positioning system

GMFMC Gulf of Mexico Fishery Management Council

H 2 S hydrogen sulfide

HAPC Habitat Area of Particular Concern

HOSS high

- volume open sea skimmer

IPF impact

- producing factor

MARPOL International Convention for the
Prevention of Pollution from Ships MMC Marine Mammal Commission

MMPA Marine Mammal Protection A ct
MMS Minerals Management Service

MMSCFD million standard cubic feet per day

MSRC Marine Spill Response Corporation

MWCC Marine Well Containment Company
NAAQS National Ambient Air Quality
Standards

NMFS National Marine Fisheries Service

NOAA National Ocea nic and Atmospheric
Administration

NO
x nitrogen oxides

NPDES National Pollutant Discharge Elimination System

NPS National Park Service

NRDA Natural Resource Damage

Assessment

NTL Notice to Lessee

NWR National Wildlife Refuge

OBM oil

- based mud

OCS Outer Continental Shelf

OSAT Operational Scientific Advisory

Team
OSRA Oil Spill Risk Analysis

OSRB oil spill response barge

OSRP Oil Spill Response Plan

OSRV oil spill response vessel

PAH polycyclic aromatic hydrocarbon s
PM particulate matter

PSD Prevention of Significant

Deterioration

PSV p l atform supply vessel

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 case dischargeEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 1 

## Introduction

Anadarko Petroleum Corporation (Anadarko) is submitting a Supplemental Exploration Plan (EP)
for East Breaks ( EB ) Block 646 ( EB 646 )

. The EP includes two exploratory wells designated “ EE ”
and “ EEE ” to be drilled and completed in late 2013 with the surface hole location s (SHL s ) and
bottom hole locations in EB 646

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

The lease area is 119 miles ( 192 km) south

- south east of the nearest shoreline (Texas)

, 2 86 miles ( 46 1 km) from the onshore support base at Port Fourchon , Louisiana, and 2 75 miles ( 4 43 km) from the helicopter base at Houma, Louisiana ( Figure 1 ). Water depth in the project area is approximately 1,109 m (3,637 ft). The drilling rig is yet to be determined but will be either a dynamically positioned (DP) drillship

, a DP semisubmersible

.

This EIA was prepared for submittal to the Bureau of Ocean Energy Management ( BOEM) in accordance with applicable regulations, and is a project - and site

- specific analysis of Anadarko ’s planned activities

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

- G04, an EIA is a project

- specific analysis that focuses on the impacts of a specific plan to the extent feasible. Potential impacts have been analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the Outer Continental Shelf ( OCS ) Oil and Gas Leasing Program (MMS, 2007a) and in lease sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008 ; BOEM, 2012a ) . The analyses from these documents are incorporated here by reference. Updated environmental baseline information relative to the Maco ndo incident presented in the Final Supplemental EIS for Central Planning Lease Sale 216/222 (BOEM, 2012 b ) and the Final Supplemental EIS for Western Planning Area Lease Sale 218 (BOEMRE, 2011a) has also been incorporated.

Statistics from offshore drilling in the U.S. Gulf of Mexico provide a reasonable basis for evaluating oil spill risk during exploratory drilling. According to Holand (1997), the average frequency of a loss of well control incident or “blowout” during exploratory drilling in the

U.S. Gul f of Mexico is 0.00593 blowouts per well drilled, or one blowout per 169 exploration wells drilled. Similarly, the MMS Safety and Environmental Management Program blowout incident rate for 1996 to 1999 was approximately five blowouts per 1,000 well starts , or one blowout per 200 well starts ( MMS, 2000 ). More recently, in its Final Supplemental EIS for the Central Gulf of Mexico Planning Area, BOEM confirmed that “significant changes to the spill rates for the entire OCS are not anticipated” (BOEM, 201 2b ).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 2

Figure 1. Location of East Breaks Block 646

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 3 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 combined 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 BSEE’s Final Drilling Safety Rule (75 Federal Register (FR) 63365 ) issued following the Macondo incident, the baseline risk of a catastrophic blowout is estimated to be about once every 26 years

.
All the proposed activities and facilities di scus sed in this EP are covered by the Regional Oil Spill Response Plan (OSRP) approved on 2 4 August 2012 for Anadarko and its subsidiaries, Anadarko

U.S. Offshore Corporation

, and Anadarko Petroleum Corporation (Company Numbers 00981,

02219

, and 00148, res pectively) 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 resp onse program based on a regional capability of respon se to spill s ranging from small operational spills

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

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 Analysis). Table 1 lists and summarizes the NTLs applicable to this EIA.

Table 1. Notices to Lessees and Operators (NTLs) app licable to this Environmental Impact Analysis ( EIA ).

NTL Title Summary

2012- N06 Guidance to Owners and Operators of Offshore Facilities
Seaward of the Coast Line Concerning Regional Oil Spill Response Plans Provides clarification, guidance, and information for preparation of regional Oil Spill Response Plans. Recommends description of response strategy for worst case discharge (WCD) scenarios to ensure capability to respond to oil discharges is both efficient and effective.

2012- BSEE

- G01 Marine Trash and Debris
Awareness and Elimination Instructs operators to exercise caution in the handling and disposal of small items and packaging materials; requires the posting of placards at prominent locations on offshore vessels and structures; and mandates a yearly marine trash and debris awareness training and certification process.

2012- JOINT

- G01 Vessel Strike Avoidance and Injured/Dead Protected Species Reporting Recommends protected species identification gu ides be carried on all Gulf of Mexico petroleum vessels and that vessel operators and crews maintain a vigilant watch for
marine mammals . Vessels are to slow down or stop to avoid striking protected species, and operators are required to report sightings of any injured or dead protected species.

2011- JOINT

- G01 Revisions to the List of OCS Lease Blocks Requiring Arch a eological Resource Surveys and Reports Provides new information of which Outer Continental Shelf (OCS) blocks require arch a eological surveys and reports and required survey line spacing in each block. This NTL
augments NTL 2005

- G07.Table 1. (Continued).

East Breaks Block 646 March 2013
Environmental Impact Analysis for Supplemental Exploration Plan Page 4 NTL Title Summary

2010- N10 Statement of Compliance with Applicable Regulations and
Evaluation of Information Demonstrating Adequate Spill Response and Well Containment

Resources Informs operators using subsea blowout preventers (BOPs) or surface BOPs on floating facilities that applications for well permits must include a statement signed by an authorized company official stating that the operator will conduct all activities in compliance with all applicable regulations, including the increased safety measures regulations (75 FR 63346). Informs operators that BOEM will be evaluating whether each operator has submitted adequate information demonstrating that it has access to and can deploy containment resources to promptly respond
to a blowout or other loss of well control.

2010- N06 Information Requirements for Exploration Plans, Development and Production Plans, and Development Operations
Coordination Documents on the

OCS Rescinds the limitations set forth in NTL 2008- G04 regarding a blowout scenario and worst case discharge scenario, and provides guidance regarding the information required in blowout scenario and worst case discharge scenario descriptions.

2009- G40 Deepwater Benthic Communities Guidance for avoiding and protecting high

- density deepwater benthic communities (including chemosynthetic and deepwater coral communities) from damage caused by

OCS oil and gas activities in water depths greater than 300 m (984 ft). Pr escribes 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 biol ogically sensitive features and areas (i.e., topographic features, pinnacles, low relief live bottom areas, and other potentially sensitive biological features) when conducting OCS operations in water depths less than 300 m (984 ft) in the Gulf of Mexico.

2009- G06 Military Warning and Water Test

Areas Provides contact links to individual command headquarters for the military warning and water test areas in the Gulf of Mexico. Lease stipulations require lessees or designated
operators to enter into an agreement with the appropriate individual military command headquarters concerning the control of electromagnetic emissions and use of boats and aircraft in the applicable warning area or water test area before commencing such traffic.

2008- G04 Information Requirements for Exploration Plans and Development Operations Coordination

Documents Guidance on the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Enda ngered Species
Act and Marine Mammal Protection Act.

2005- G07 Archaeological Resource Surveys and Reports Provides guidance on regulations regarding archaeological discoveries, specifies requirements for archaeological resource surveys and reports, and ou tlines options for protecting archaeological resources.
BOEMRE = Bureau of Ocean Energy Management, Regulation and Enforcement; BSEE = Bureau of Safety and
Environmental Enforcement.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 5 

## A. Impact

- Producing Factors

Table 2 is a matrix of impact

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

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

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

. Potential IPFs for the proposed activity are listed 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 ves sel and helicopter traffic

• Accidents



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

Two types of exploratory drilling rigs are being considered for this project:

• DP drillship; and

• DP semisubmersible

.
DP drillships and DP semisubmersibles use a global positioning system (GPS) , specific computer software, and sensors in conjunction with their own propellers and thrusters to maintain position. T hrough satellite navigation, the location of the vessel is precisely moni tored, and thrusters positioned at various locations about the vessel’s hull are activated to provide required station

- keeping adjustment. This allows operations at sea where mooring or anchoring
is not feasible.

The drilling vessel for the well s proposed in this EP will be on site for an estimated 210 days total ( 1 0 5 days/well)

. T he physical presence of the drilling rig in the ocean can attract pelagic fishes
and ot he r marine life

, as discussed in Section C.5.1

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

in some cases infrasonic frequencies (MMS, 2000). Drilling noise from DP drillships and

DP semisubmersibles is not particularly intense and is strongest at low frequencies, averaging

10 to 500 Hz (Richardson et al., 1995). From a drilling rig , sound and vibration paths to the water flow either through the air or through the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with applicable Federal safety regulations.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 6 Table 2. Matrix of impact

- producing factors and affected environmental resources. X = potential impact; dash (

-- ) = no impact or negligible impact.

Environmental Resources Impact

- producing Factors Drilling Rig Presence (incl. noise & lights) Physical Disturbance to Seafloor Air Pollutant Emissions Effluent Discharges Water Intake Onshore Waste Disposal Marine Debris Support Vessel/Helo

Traffic Accidents Small Fuel Spill Oil Spill (WCD) Physical/Chemical Environment Air quality and greenhouse gases

-- -- X ( 9 )

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

-- -- -- X

-- -- -- -- X (6) X (6) Seafloor Habitats and Biota Soft bottom benthic communities

-- X

-- X

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

- density deepwater benthic communities

-- -- (4)

-- -- (4)

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

-- -- (1)

-- -- ( 1)

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

-- -- (2)

-- -- (2)

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

-- -- (3)

-- -- (3)

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

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

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

-- X (6,8) Endangered mysticete 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 (6) Wetlands and seagrass beds

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

-- -- -- -- -- -- -- -- -- X (6) Socioeconomic and Other Resources

Recreational and commercial fishing X

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

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

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

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

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

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

WCD = worst case discharge.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 7 Table 2 Footnotes and Applicability: (1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, rig site, or any anchors will be on the seafloor within the following: (a) 4- mi zone of the Flower Garden Banks, or the 3

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

- m, 1

- mi, or 3

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

- activi ty zone; or (d) Proximity of any submarine bank (500

- ft buffer zone) with relief greater than 2 m that is not protected by the Topographic Features Stipulation attached to an OCS lease.

• Not applicable. The lease is not within or near any marine sanctuary, topographic feature, or no

- activity
zone. There are no submarine banks in the blocks.
(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.

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

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

- Relief) Stipulation attached to an OCS lease.

• The Live Bottom (Low

- Relie f) Stipulation is not applicable to the lease area.

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

• No impacts on high

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

- density chemosynthetic communities or coral communities within 610 m ( 2,000 ft) of any drilling mud/cuttings discharge location.
(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be encountered.

• Based on 30 CFR 250.490(c), Anadarko is request ing that BOEM classify the area as "H 2 S absent ."

(6) All activities that could result in an accidental spill of produced liquid hydrocarbons or diesel fuel that you determine would impact these environmental resources. If the proposed action is located a sufficient distance from a resource that no impact would occur, the EIA can note that in a sentence or two.

• Accidental hydrocarbon spills could affect the resources marked (X) in the matrix, and impacts are analyzed in Sect ion C

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

- probability for the occurrence of shipwrecks or prehistoric sites, including such blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would occur, the EIA can note that in a sentence or two.

• No impacts on archaeological resources are expected. The lease area is not on the list of archaeology survey blocks (BOEM, 2012 c) and is well beyond the 60

- m depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico.
(8) All activities that you determine might have an adverse effect on endangered or threatened marine mammals
or sea turtles or their critical ha bitats.

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

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

• Not applicable.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan 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 (BOP) are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac) (MMS, 2007 a).

An anchored semisubmersible drilling rig may be used. Anchoring causes physical comp action of the seafloor beneath the anchor, and chains or lines can disturb the bottom as well as resuspend sediments as they move about. A disturbed area on the sea bottom, called the “anchor sweep,” forms by the swing arc of anchor lines scraping across bottom within the range allowed by the anchoring system configuration (BOEMRE, 2011 a ). Anchored semisubmersibles disturb approximately 2 to 3 ha (5 to 7 ac) of seafloor, depending on the number of anchors and their mooring configurations (MMS, 2007a).



## A.3 Air Pollutant Emissions

Air pollutant emissions are calculated in EP Section G and are estimated to be insignificant. Offshore air pollutant emissions will result from operations of the drilling rig, as well as service vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The
combustion of fuels occurs on diesel

- powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended particulate m atter (PM), sulfur oxides (SO
x ), nitrogen oxides (NO
x ), volatile organic compounds (VOCs), and carbon monoxide (CO).

The Air Quality Emissions Report prepared in accordance with BOEM requirements
demonstrates that the projected emissions are below exemptio n 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. GMG 290000 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 prior to installation of the marine riser

, which allow s thei r return to the surface. 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 either reused by the vendor or transported to Port Fourchon for recycling and/or disposal at an approved facility. Cuttings wetted with SBMs will be discharged to the seafloor in accordance with the NPDES permit.

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

non contact cooling water, treated sanitary and domestic wastes, dec k drainage, desalination unit brine, unco ntaminated freshwater and seawater, and ballast water.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 9 

## A.5 Water Intake

Seawater will be drawn from the ocean for once

- through, non contact cooling of machinery on the drilling rig. Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organi sms. The current NPDES General P ermit No. GMG 290000 does not specify requirements for existing facilities (those that started construction before

16 July 2006)

. The DP drilling vessel ultimately selected for this project will be in compliance
with all co olin g water intake structure requirements.



## A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in EP Section F

. Approximately 50 bbl of trash will be generated each month of operations, or a total of approximately 250 bbl over the life of this project. 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 relat ing to solid wastes handling and disposal, including the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements and USEPA and U.S. Coast Guard ( USCG ) regulations, as
well as those of the BOEM

. For example, BOEM regulations at 30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (i.e., trash and debris) into the marine environment, and 30 CFR 250.300(c) requires durable identification markings on equipment, tools

, and containers (especially drums), and other
material. USEPA and USCG regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, posting informational placard s, manifesting trash sent to shore, and using special precautions such as covering outside trash bins to prevent accidental loss of solid waste. In addition to the regulations in 30 CFR 250

, BSEE issued NTL 2012

- BSEE -G01, which instructs operators to exer cise 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

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

- trips per week, and the supply vessel will make two round

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

A helicopter will make approximately 10 round

- trips per week between the drilling rig and the heliport. The helicopter will be used to transport personnel and small supplies and will normally
take the most direct route of travel between the shorebase and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 213 mEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 10 (700 ft) while in transit offshore, 3 05 m (1,000 ft) over unpopulated areas or across coastlines,
and 610 m (2,000 ft) over populated areas and sensitive habitats such as wildlife refuges and park properties. Additional guidelines and regulations specify that helicopters maintain an
altitude of 1,000 ft (305 m) within 300 ft (91 m) of marine mammals (BOEM, 2012 d ).



## 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 a re analyzed in Section C

.

MMS ( 2007b)

, BOEMRE (2011 a), and BOEM (2012 b ) 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 Fue l Spill

Spill Size . According to the analys e s in MMS (2007b ) and BOEM (201 2a ), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills have been < 1 bbl, and this size is predicted to be the most common in ongoing and
future OCS activities in the Western and Central Gulf of Mexico Planning Areas. As the spill size increases, the incident rate declines dramatically (MMS, 2007b ; BOEMRE, 2011a; BOEM, 201 2b ).
The median size for spills < 1 bbl is 0.0 24 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl ( BOEM, 2012a ). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate

The water

- soluble fracti ons 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 aerobic microbial oxidation. Due to its light density, diesel will not sink to the
seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solids lo ads (National Research Council, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes ( National Oceanic and Atmospheric Administration [ NOAA ] , 2006). . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiveness of spill response activities. However, 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 ( BOEMRE, 2011a; BOEM, 201 2b).

For purposes of this EIA, t he fate of a small diesel fuel spill was estimated using NOA A’s Automated Data Inquiry for Oil Spills 2 (ADIOS2) model. This model uses the physical propertiesEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 11 of oils in its database to predict the rate of evaporation and dispersion over time, as well as changes in the density, viscosity, and water content of the product spilled. I t is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of
the s ea surface with diesel fuel on it during this 24

- hour period would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill,
indicat e that a small fuel spill would not have any impacts on coastal or shoreline resources.
The lease area is 119 miles ( 192 km) from the nearest shoreline (Texas)

. Modeling results discussed below indicate that a spill in the lease area w ould have an 18 % or less probability of reaching the coastal areas of Texas 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 m easures. 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 th is conclusion is supported by a previous analysis of three

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

Spill Response



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

- term environmental consequences.

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

.

Spill Size

Historically, blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a . Anadarko has d etermined that the WCD for EB 646 exploratory wells " EE " and " EEE " is below the previously approved WCD estimate for the block. The detailed analysis of this
calculation can be found in EP Section H

. The WCD for EB 646 is 139,700 bopd (crude, API 27.1)
for Well " FF " as approved under Plan C ontrol No. N

- 9591. In accordance with requirements of

NTL 2010

- N06, the highest approved po tential WCD for the EB 645 and 646 plan area is estimated to be 155,400 bopd (crude, API 27.1) at Well " EE " in EB 645 as approved under Plan

C ontrol No. N

- 9591. Therefore, for purposes of the blowout scenario, the largest potential spill
volume would be 1 55,400 bopd in accordance with the approved submission for the EB 645 and 646 plan area.

deep drilling

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

NTL 2010

- N06, including descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a bl owout. Anadarko blowout during explor ation drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per exploratory well for non

- North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil. BOEM is in the process of updating these spill frequency estimates to include the Macondo event; however, significant changes to the spill rates for the entire OCS are not anticipated ( BOEMRE, 2011 a ; BOEM, 2012 d ). As noted in the Introduction , the baseline risk of a catastrophic blowout is estimated to be once every 26 years ( BSEE Final Drilling Safety Rule, 75 FR 63365).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 12 will also comply with NTL 2010 -N 10 and the Final Drilling Safety Rule, which specif ies additional safety measures for OCS activities.

Spill Trajectory

To address this criticism

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

, 2011 a ; BOEM, 2012 b ) in order to estimate the impacts of a possible fu ture 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 t racked for up to 120 days. . The fate of a large oil spill in the lease area would depend on meteorological
and oce anographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that uses realistic data for winds and currents to predict spill fate. Although this model has received some criticism recently (E arthjustice, 2011), it is still the most widely scientifically accepted model for estimating the fate of small fuel spills.
The primary criticism of the OSRA model results as provided in Ji et al. (2004) was that the
model did not evaluate the fate of a spill over time periods longer than 30 days, nor d id it predict the fate of a release that continues over a period of weeks or months, as in the Macondo
incident. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size but has generally been used by the BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.

The OSRA model run for this revised analysis was conducted for five hypothetical launch points
in the Central 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 launch point areas were as follows:

1. Central Gulf of Mexico shelf area west of the Mississippi River (28.98660° N latitude, 92.17851 ° W longitude);

2. Central Gulf of Mexico shelf area east of the Mississippi River ( 29.91388 ° N latitude, 88.15338 ° W longitude);

3. Central Gulf of Mexico slope area ( 27.31998 ° N latitude, 90.22203 ° W longitude);

4. Western Gulf of Mexico shelf area ( 27.55423 ° N latitude, 96.76627 ° W longitude); and

5. We stern Gulf of Mexico slope area ( 27.51367 ° N latitude, 94.51836 ° W longitude).

The results for Launch Point 5 , 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 curren t data would continue on a daily basis to help position equipment and human resources throughout the duration of any major spill or uncontrolled release

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 13 Weathering

Table 3. Conditio nal probabilities expressed as percent chance that an oil spill starting at Launch Point 5 will contact a certain parish, county, or coastline within 120 d ays (Modified from: BOEM, 201 2b , Appendix C).

. Following an oil spill, several physical, chemical, and biological processes,
collectivel y called weathering, interact to change the physical and chemical properties of the oil, influencing potential effects to marine organisms and ecosystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water

- in

- oil emulsions, photochemical oxidation, microbial degradation, adsorption to suspended particulate matter, and stranding on shore or sedimentation to the seafloor (National Research Council, 2003).

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 4

-- -- -- -- -- -- 2 3

-- -- 3 5
Willacy, Texas

-- -- 1 4

-- -- -- -- -- -- 2 3

-- -- 2 3
Kenedy, Texas

-- 1 8 14

-- -- 1 1

-- -- 4 7

-- -- 6 9
Kleberg, Texas

-- -- 5 7

-- 1 2 2

-- -- 1 3

-- -- 4 5

Nueces, Texas

-- 1 5 9

-- 1 2 2

-- -- 1 1

-- -- 3 5

Aransas, Texas

-- 1 5 10

-- -- 3 3

-- -- 2 3

-- -- 4 6
Calhoun, Texas

-- 2 10 20

-- 3 11 12

-- -- 7 9

-- 1 5 7
Matagorda, Texas

-- 1 8 14

-- 18 29 30

-- 2 12 21

-- 2 9 15

Brazoria, Texas

-- -- 3 4

-- 9 13 13

-- -- 7 12

-- 1 4 6
Galveston, Texas

-- 1 2 4

-- 3 11 13

-- -- 5 12

-- 1 2 3
Jefferson, Texas

-- -- -- 1

-- -- 12 15

-- -- 1 4

-- -- -- 1

Cameron, Louisiana

-- -- -- 1

-- 1 5 6

-- -- 6 8

-- -- -- -- Vermilion, Louisiana

-- -- -- -- -- -- 2 3

-- -- 1 2

-- -- -- -- Plaquemines, Louisiana

-- -- -- -- -- -- -- -- -- -- -- 1

-- -- -- --

“--” = Values < 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 i n the oil on the
water surface.

Spill Response

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

- spill prevent ion and response planning requirements. These NTL s are summarized in Table 2

, and additional BOEM (2012 b) guidance is provided below.

NTL 2012

- N06 – Guidance to Owners and Operators of Offshore Facilities Seaward of the Coast Line Concerning Regional Oil Spill Response Plans: This NTL, effective 10 August 2012, provides clarification, guidance, and information on the preparation and submittal of regional OSRPs for owners and operators of oil handling, storage, or transportation facilities, inclusive of pipelines, located seaward of the coastline.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 14 It states that lessees, designated operators, and pipeline right

- of

- way holders are responsible for preparation and submission of these plans. Some of the clarifications and recommended practices in the NTL are ba sed on lessons learned from the Macondo oil spill

response.

NTL 2010

- N10 – Statement of Compliance with Applicable Regulations and Evaluation of Information Demonstrating Adequate Spill Response and Well Containment Resources : This NTL, effective 8 November 2010, applies only to operators conducting operations using subsea or surface BOPs on floating facilities. It explains that lessees and operators must submit a statement signed by an authorized company official with each application for a well pe rmit indicating that they will conduct all of their authorized activities in compliance with all applicable regulations, including the Increased Safety Measures Regulations at

75 FR 63346. The NTL also informs lessees that BOEMRE will be evaluating whethe r or not each operator has submitted adequate information demonstrating that it has access to and can deploy surface and subsea containment resources that would be adequate to promptly respond to a blowout or other loss of well control. The NTL notifies t he operator that BOEMRE intends to evaluate the adequacy of each operator to comply in the operator’s current OSRP; therefore, there is an incentive for voluntary compliance.

NTL 2010

- N06

– Information Requirements for Exploration Plans, Development and

Pr oduction Plans, and Development Operations Coordination Documents on the OCS

Anadarko submitted a Regional OSRP to BOEM

, which was approved on 2 4 August 2012. The

OSRP provide s detailed plan s for Anadarko to respond to and rapidly and effectively manage oil spills that may result from drilling and production oper ations. The OSRP contains detailed information on “Quick Response” procedures including : : This NTL, effective 18 June 2010, explains the procedures for the lessee or operator to submit supplemental information for new or previously submitted EPs, Development and
Produ ction Plans (DPPs) , or D evelopment O perations C oordination D ocument s (DOCDs)

. The required supplemental information includes the following: 1) a description of the blowout scenario as required by 30 CFR 2 50.213(g) (for EPs) and 2 50.243(h) (for DPPs and DOCDs) ; 2) a description of the assumptions and calculations used in determining the
volume of the WCD required by 30 CFR 2 50 .219 (for EPs) or 30 CFR 2 50.250 (for DPPs and DOCDs); and 3) a description of the measures proposed that would enhance the ability to prevent a blowout, to reduce the likelihood of a blowout, and to conduct effective and early intervention in the event of a blowout, including the arrangements for drilling relief wells and any other measures proposed. The early intervention methods o f the third requirement could actually include the surface and subsea containment resourc es that
BOEM announced in NTL 2010

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

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

• procedures to locate and determi ne the size of a discharge; and

• c ontact information for alerting the spill management team complete with names, phone numbers, and locations.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 15 In the event of a WCD, Anadarko has access to surface and subsea response/containment capabilities that could be implemented thr ough various organizations under contract. Anadarko's primary spill response equipment provider is Clean Gulf Associates (CGA).

CGA has four skimming vessels capable of operating in shallow waters and offshore/nearshore

areas. These vessels have o leophilic brush pack skimming systems operating in troughs built
into the hulls below deck storage and marine electronics packages including marine, aircraft and

company

- frequency radios, radar, moving map plotters

, GPS, satellite phone s , and depth
finders

. CGA also offers nine Fast Response Systems staged throughout the Gulf of Mex ico
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 recov ered oil storage tanks built into the hull where oil can be separated and offloaded. Skimming operations are conducted from the control room overlooking the skimmer deck. The estimated daily recovery capacity for the HOS S barge is approximately 43,000 bb l.

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

- band radar/infrared tracking system is installed on the HOSS barge. Additional CGA equipment can be refer enced on the website: http://www.cleangulfassoc.com/

.

Anadarko also has a contract with the Marine Spill Response Corporation (MSRC) for additional spill response equipment. MSRC has a dedicated fleet for the A tlantic/ Gulf of Mexico region and additional available equipment staged throughout the U

. S. The equipment MSRC staged throughout the Gulf of Mexico includes 7 oil spill response vessels (OSRVs), 2 fast response vessels (FRVs), 5 oil spill response barges (OSRBs), 5 platform supply vessels (PSVs), and

15 shallow water barges. Various equipment is outfitted with x

- band and infrared technology.

MSRC recently completed a large expansion of its resources and capability in the Gulf of Mexico, with particular fo cus on deep water. The expansion is known as “Deep Blue.” Additional MSRC capabilities and a complete equipment listing is available on

- line at: http://www.msrc.org/

.

Anadarko also is a member of the Marine Well Contain ment 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 rise rs. The interim system is engineered to be used in depths up to 3,048 m (10,000 ft) and has the capacity to contain 60,000 barrels of liquid per day (BLPD) (and 120 million standard cubic feet per day [MMSCFD] of gas) with potential for expansion.

See EP Section H 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 c ontrol. The information from the EIS on these topics remains valid and is incorporated by reference into this document. These accidents are discussed briefly below along with a hydrogen sulfide ( H 2 S) release . T here are no other site

- specific issues rais ed for the drilling of
the well proposed in this EP.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 16 Chemical Spills

. Chemicals are stored and used to condition drill muds and during production and in well completions, stimulation, and workover procedures. The relative quantity of their use is reflected in the largest volumes spilled. Completion fluids are the largest quantity used
and comprise the largest releases. Between 5 and 15 chemical spills are anticipated each year, with the majority being <50 bbl in size. The most common chemicals spilled are methanol, ethylene glycol, and zinc bromide. Additional production chemicals are needed in deepwater operations where gas hydrates tend to form. Spill volumes are anticipated to remain about the same, but spill frequency can be expected to decrease because of advances in subsea processing ( BOEMRE, 2011 a ; BOEM, 2012 b).

Riser 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 f luid s used in SBMs are less toxic to the marine environment and have the potential to biodegrade.
SBMs have been used in the Gulf of Mexico since the mid

- 1990 s , and between 5 and 20 SBM releases are anticipated each year as a result of offshore drilling programs. The majority of these releases are <50 bbl in size, but accidental riser disconnects may result in the release of medium (238 to 2,380 bbl) to large (>2,381 bbl) quantities of drilling fluids. Riser disconnect accidents are of particular concern when SBMs are in use ( BOEMRE , 201 1b ).

Vessel Collisions

. BOEM data show that from 1996 to 2009 there were 226 OCS

- related
collisions. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline ri sers. 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 Main 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 approximately half of all reported vessel collisions from

2006 to 2009. As summarized in MMS (2007b ) and BOEM (201 2b ), vessel collisions occasionally occur during routine operations. Some of these collisions have caused spills of diesel fuel or
chemicals. Anadarko will comply with all USCG - and BOEM

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

Loss of Well Control . A loss of well control is the uncontrolled flow of a reservoir fluid that may result in the release of gas, condensate, oil, drilling fluids, sand, or water. Loss of well control is a broad term that includes very minor up to the most serious well control incidents, while
blowouts are cons idered to be a subset of more serious incidents with greater risk of oil spill or human injury (MMS, 2007b). Loss of well control may result in the release of synthetic drilling
fluid or loss of oil. Anadarko has a robust system in place to prevent loss of well control.

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 regulations such as the Final Drilling Safety Rule ( Federal Register,
2012 ) and NTL 2010

- N10 , which specify additional safe ty measures for OCS activities.

H 2 S Release

. Pursuant to 30 CF R 250.4 90 (c), Anadarko is requesting in the EP that the BOEM Regional Supervisor, Field Operations, classify the area of 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.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 17 

## B. Affected Environment

The lease area is in the western Gulf of Mexico, 119 miles ( 192 km) from the nearest shoreline,
and 2 86 miles ( 46 1 km) from the onshore support base at Port Fourchon , Louisiana ( Figure 1 ).

Based on the site clearance s urvey conducted b y Geoscience Earth & Marine Services, Inc. ( as referenced in GEMS

, 2012) w ater depth at the wellsite s is approximately 1,109 m (3,637 ft) ( Figure 2 ). There is evidence of seafloor faulting and likely indications of authigenic carbonates
which can increase the potential for high

- density chemosynthetic and other benthic

communities.

A detailed description of the regional affected environment, including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered s pecies, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses i s provided in recent lease sale EISs (MMS, 2007b, 2008 ; BOEM, 2012a ). These regional descriptions remain valid and are incorporated by ref erence. General background information is presented below, and brief descriptions of each potentially affected resource, including site

- specific and/or new information if available

, are presented in
Section C

.
The Macondo spill resulted in impacts to water quality in the area of the spill. In addition to the
oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants 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 offshore water quality (BOEMRE, 2011a; BOEM, 2012 a ).

The lease area is located approxi mately 382 miles ( 615 km) west

- south west of the Macondo spill

site. Based on an analysis of satellite imagery, the surface slick did not extend over the lease

area , and the existing water quality in the lease area is not expected to have been 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 on the information currently available, there is no reason to expect any long

- term change in water quality conditions in the lease area from those predicted in the recent lease sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 18

Figure 2. Bathymetric map of the lease area showing the proposed surface hole location s.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan 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 extensively in recent lease sale EISs for the Central and Western
Gulf of Mexico Planning Areas (MMS, 2007b

, 2008; BOE MRE

, 2011 a ; BOEM, 2012 b ) as well as
the E nvironmental A ssessment 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 the distance from shore

. Because of the distance from shore

- based pollution sources and the lack of sources offshore

, air quality at the wellsite is expected to be good. The attainment status of Federal OCS waters is unclassified because there is no provision in the Clean Air Act for classification of areas outside

State waters (MMS, 2007b)

.
As noted earlier, based on calculations made pursuant to applicable regulations, emissions from drilling activities are not expected to be significant as they are below exemption levels. Therefore, the only potential effects to air quality would be from routine air pollutant emission s,

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

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

. No substantial new
information was fou nd that would alter the potential impact s on air quality presented in previous lease sale EIS s ( BOEMRE

, 2011 a ; BOEM, 2012 b ).



### Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pol lutant emissions will result from the drilling rig operations and helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel

- powered generators, pumps, or mo tors 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 BOEM 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 BOEM completed the lease sale EISs, the USEPA has adopted a new short

- term NAAQS for nitrogen dioxide. The standard has not yet been implemented in the Gulf Coast states, but given the levels of expected emissions and the distance of the project from shore, emissions
from the activities describ ed in Anadarko’s propose d EP are not likely to contribute to violations of any NAAQS onshore.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 20 Carbon dioxide (CO 2 ) and methane ( CH 4 ) emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activ ities. 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 emissions may contribute to climate change, with important effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Change, 2007). Greenhouse gas emissions from this proposed project represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the lease sale EIS (MMS

, 2007b) or Programmat ic EIS (MMS, 2007a).

Because of the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast, including nonattainment areas. As noted in the lease sale EIS (MMS, 2007b)

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

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

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

.
The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air quality area. The BOEM is required to notify the National Park Service (NPS) and U.S. Fish and Wildlife Service ( USFWS ) if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sources within 186 miles (300 km) of the Breton Class I area that e xceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 351 miles ( 565 km) from the Breton
Wilderness Area

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



### Impacts of a Small Fuel Spill

Potential 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, 2 011 a ; BOEM, 2012 b ). The probability of a small spill would be minimized by Anadarko ’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation of Anadarko ’s OSRP will reduce the potential impacts. EP Section H includes a
detailed discussion of the spill response measures that would be employed

. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A sm all fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model ( see Section A.9.2 ) indicates that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the se a 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.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan 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 a ; BOEM, 2012 b ).

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

measures. Real

- time wind and current data from the project area would be available at the time of a spill and would be used to assess the fate and effects of VOCs released. Additional air quality impacts could occur if response measures included in situ burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of NO x , SO x , CO, and PM, as well as greenhouse gases. However, in situ burning would occur only after authorization
f rom the USEPA.

Because of the lease area location ( 119 miles [ 192 km ]) from the nearest shoreline, most air quality impacts would occur in offshore waters with minimal chance to affect onshore air quality.



### C.1.2 Water Quality

There are no site

- specific water quality data for the lease area. Due to the lease location in deep, offshore waters, water quality is expected to be good, with low levels of contaminants.

As noted in a recent lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occurrences of natural seepage of oil, gas, and brines in near

- surface sediments and up through the water
column.

The lease area is located approximately 382 miles ( 615 km) fr om the Macondo spill site

. Based on the general circulation pattern seen in the Gulf of Mexico and satellite imagery, the surface
slick from that discharge did not extend over the lease area during the spill

, and the existing water quality in the lease area is not expected to have been affected by the Macondo release.

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

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



### Impacts of Effluent Discharges

In general, turbid water can be expected to extend between a few hundred meters and seve ral
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 w ater quality
in the lease area ( National Research Council , 1983; Neff, 1987 ; Neff et al., 2000 ).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 22 Treated sanitary and domestic wastes , including those from support vessels, may have a slight transient effect on water quality in the immediate vicinity of these discharges. All NPDES permit limitations and requirements and USCG regulations (as applicable) will be met , therefore, 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 rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements. Based on adherence to permit limits and applicable regulations, little or no impact on water quality is anticip ated.

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 a ; BOEM, 2012 b ). The probability of a small spill would be minimized by Anad arko ’s preventative measures during routine operations

, including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially help mitigate and reduce the impacts. EP Section H provides
detail on spill response measures in addition to the summary information provided in this EIA

. Given the open ocean location of the lease area, the extent and duration of water quality impacts from a small spill would not be significant.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at

t he time and the effectiveness of spill response measures. However, it is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours (see Section A.9.2 ). The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac) depending on sea state and weather conditions.

The water

- soluble fractions of diesel are dominated by two - and three

- ringed PAH s , which are moderately volatile (National Research Council, 2003). The constituents of these oi ls are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel is so light that it is not possible for the oil to sink and pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high suspended solid loads (National Research Council, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

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

to make landfall or reach coastal waters due to both response efforts that would be unde rtaken
as well as natural attenuation (see Section A.9.2 ).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan 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, 200 8). 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 (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). However, dispersants would be applied only after approval from the USEPA. Small droplets in the water may adhere

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

Because of the lease area location ( 119 miles [ 192 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 project area is approximately 1,109 m (3,637 ft)

. The seafloor dips slightly to the northwest at approx imately 1.7° (3.0%). The proposed wellsite s are in a shallow
low within a northeast

- southwest trendi ng fault system. The seafloor at the proposed wellsite s is irregular and the near

- surface sediments are expected to be normally consolidated soft clays forming a drape over the area

. The immediate regions between 488 m and 579 m (1,600 and 1,900 ft) from the proposed well locations show the potential for mino r benthic community development. However

, there is no evidence of high

- density chemosynthetic and other benthic communities within 610 m (2,000 ft) of the proposed wellsites (GEMS, 2012).



### C.2.1 Soft Bottom Benthic Communities

There are no site

- specific benthic community data from the lease area. However, data from the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (Wei, 2006;

Rowe and Kennicutt, 2009) can be used to describe typical benthic communities in the area.
Table 4 s ummarizes data collected at three stations in water depths similar to the proposed drilling area.

Table 4. Benthic community data from stations near the lease area in similar water depths sampled during the Northern Gulf of Mexico Continental Slope Habitat s and Benthic Ecology Study (Adapted f rom: Wei, 2006; Rowe and Kennicutt, 2009).

Station Water Depth (m) Abundance

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

RW3 1,318 248,752 1,641 195

RW4 1,570 232,842 1,399 762

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

Wei (2006).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 24 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 ( 1,100 m ) typically range from approximately 200,000 to 550,000 individuals/m 2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant meiofaunal groups, accounting for
about 90% of total abundance.

The benth ic macroinfauna is characterized by small mean individual sizes and low densities, both of which reflect the meager primary production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equation

p resented by Wei (2006), macroinfaunal densities in the water depths of the lease area are expected to be about 3,0 00 individuals/m 2 , or higher than the numbers for the closest locations
listed in Table 4

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

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

- dependent faunal zones (1 through 4), two of which are divided
ho r izontally. The lease area is in Zone 2W. W ith stations in water depths of 863 to 1, 620 m (2,831 to 5,315 ft) , t he most abundant species in this z one were the polychaetes Tharyx marioni



### , Levinsenia uncinata

, Paraonella monilaris

, Macrochaeta clavicornis , and Aricidea suecica

.
Megafaunal densities from nearby stations RW3 and RW 4 were 195 and 762 individuals/ha, respectively ( Table 4 ). Common megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal fishes as well as sessile groups such as sponges and

anemones.

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

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

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

IPFs potentially affecting benthic communities are physical disturbance to the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) resulting from a well blowout
at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Impacts of Physical Disturbance to the Seafloor

In water depths such as those encountered in the lease area, DP drillships or se misubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac). If an anchored semisubmersible is used, it is anticipated that approximately 2 to 3 ha (5 to 7 ac) of seafloor would be disturbed, depending on the number of anchors and their mooring configurations (MMS, 2007a).

T he areal extent of these impacts from the drilling rig will be small compared to the lea se 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 communities in the region

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 25 

### Impacts of Effluent Discharges

Drilling muds and cuttings are the only effluents that are likely to affect benthic communities. During initial well interval(s) before the marine riser is set, cuttings and seawater

- based “spud mud” will be released at the seafloor. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry components typically include cement mix and some of the same chemicals used in water

- based drilling muds (Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling muds, and cement slurry will eventually be recolonized through larval settlement and migration from adjacent areas. Because some deep

- sea biota grow and reproduce slowly, recovery may require several years.

Discharges of washed SBM cuttings from the rig may affect benthic communities, primarily within several hundred meters of the wellsite. The fate and effects of SBM cuttings have been reviewed by Neff et al. (2000), and monitoring studies have been conducted in the Gulf of Mexico by Continental Shelf Associates, Inc. (2004, 2006). In general, washed cuttings with adhering SBMs tend to clump together and form thick cuttings piles close to the drillsite. Areas of SBM cuttings deposition may develop elevated organic carbon concentrations and anoxic conditions (Continental Shelf Associates, Inc., 2006). Where SBM cuttings accumulate in concentrations of approximately 1,000 mg/kg or higher, benthic infaunal communities may be adversely affected due to both the toxicity of the base fluid and organic enrichment (with resulting anoxia) (Neff et al., 2000). Infaunal numbers may increase and diversity may decrease as opportunistic species that tolerate low oxygen and high H 2 S predominate (Continental Shelf Associates, Inc., 2006). As the base synthetic fluid is decomposed by microbes, the area will gradually return to pre

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

T he areal exte nt of impacts from drilling discharges will be small. Assuming a typical effect
radius of 500 m (1,640 ft), the affected area around the wellsite would represent about 3% of the seafloor within a lease block. Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic communities in the region.



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

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

Recent lease sale EISs (MMS, 2007a, 2008) in 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 andEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 26 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, 2 010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 300

- m (984

- ft) radius estimated by MMS (2007a, 2008)

, depending on its extent, trajector y, 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 as sociated high

- density hard bottom

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

CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities. The nearest known high density deepwater benthic community is approxim ately 4 miles ( 6 km) north

- northwest of the lease

area in EB 602 and consists of a seep mytilid/mussel community

.
The immediate regions between 488 m and 579 m (1,600 and 1,900 ft) from the proposed well locations show the potential for minor benthic community development. However, there is no evidence of high

- density chemosynthetic and other benthic communities with in 610 m (2,000 ft) of the wellsites (GEMS, 2012).

IPFs potentially affecting high

- density deepwater benthic communities include physical disturbance of the seafloor, effluent discharges (drilling muds and cuttings), and a large oil spill (WCD) from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on the sea surface.



### Impacts of Physical Disturbance to the Seafloor

In water depths such as are encountered in the lease ar ea, DP drillships or semisubmersibles disturb the seafloor only around the wellbore (SHL) where the bottom template and BOP are located. Depending on the specific well configuration, this area is generally about 0.25 ha (0.62 ac). If an anchored semisubmersible drilling rig is used, approximately 2 to 3 ha (5 to 7 ac)
of seafloor would be disturbed, depending on the number of anchors and their mooring configu rations (MMS, 2007a).

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

- G40 requires that high

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

- density chemosynthetic communities, or deepwater corals communities be avoided. Physical disturbance of the seafloor during this project sh ould have no impact on chemosynthetic or deepwater coral communities in the region. Based on the GEMS (2012) report, there will be no impacts on chemosynthetic or deepwater coral communities from this project.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 27 

### Impacts of Effluent Discharges

The immediate regions between 488 m and 579 m (1,600 and 1,900 ft) from the proposed well locations show the potential for minor benthic community development. However, there is no evidence of high

- density chemosynthetic and other benthic communities within 610 m (2,00 0 ft) of the wellsites (GEMS, 2012). 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 deposit s may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006; Neff et al., 2005). Because of the water depth of the lease area, drilling discharges would be expected to result in thinner, more diffuse accumulations on the seafloor than those documented in the literature. Although small amounts of cuttings particles may reach areas inhabited by high

- density deepwater benthic communities, the discharges are not expected to result in significant impacts to these

communities.



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

Recent analyses ( BOEM, 2012a ) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month ( Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potentia l to contact high

- density deepwater benthic communities beyond the 300

- m (984

- ft) radius estimated by

BOEM ( 2012a ), depending on its extent, trajectory, and persistence. Oil plumes that contact sensitive deepwater benthic communities before degrading coul d potentially impact the community (BOEM, 2012a). Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants, and such approval would be obtained from the USEPA prior to the ir use

.
The biological effects and expected fate of the oil remaining in the Gulf of Mexico from the blowout are still unknown due to the depth and magnitude of th e event. Hazen et al. (2010) reported changes in plume hydrocarbon composition with distance from th e 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 plu me in the deepwater column without substantial oxygen drawdown.

Potential impacts of oil on high

- density deepwater benthic communities are discussed in

BOEM ( 2012a ). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very constant and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep organisms also require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; change in sediment characteristics; and reduction or loss of one or more commercial and recreational fisheryEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 28 habitats. While some chemosynthetic communities may reappear relatively quickly, periods as long as hundreds of years may be required to reestabl ish a chemosynthetic seep community once it has disappeared (BOEM, 2012a). Sublethal effects to coral colonies could be long

- lasting
and affect the ir resilience of natural disturbances (e.g., elevated water temperature and diseases).

The potential for a s pill to affect deepwater corals is indicated by preliminary findings from a recent (October 2010) survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). Government and academic researchers were working at a site 1,400 m (4,600 ft) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead when they observed dead and dying corals with sloughing tissue and discoloration. Much of the soft coral observed in an area measuring about 15 by 40 m (50 by 130 ft) was covered by what appeared to be a brown flocculent substance (floc). Out of 40 large corals, 90% were heavily affected and showed dead and dying parts and discoloration. Another site 400 m (1,312 ft) farther away had a colony of stony corals similarly affected and p artially covered with a similar brown substance. Based on hopanoid petroleum biomarkers from the floc, researchers concluded that it contained oil from the Macondo spill. The injured and dead corals were in an area where a subsea plume of oil had been do cumented during the spill in June, 2010; corals elsewhere in the Gulf of Mexico outside the area affected by the plume did not appear to be experiencing higher mortality. The research team concluded that the observed coral injuries likely resulted from ex posure to the subsurface o il plume (White et al., 2012). Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants , and such approval would be obtained from the USEPA prior to the ir use

.



### 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 West Flower Garden
Bank

, 34 miles ( 55 km) north of the lease area.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.



### C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Botto m (Pinnacle Trend) Stipulation. As defined by

NTL 2009

- G39, the nearest pinnacle trend is Main Pass Block 290

, 3 88 miles ( 624 km)

east

- north east o f the lease area.

There are no IPFs associated with either routine opera tions or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small fuel spill would float on the surface and would not reach these seafloor features.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 29 In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf edge

.



### C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low

- Relief) Stipulation, which applies to

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

- G39, is
Destin Dome Block 57 3 , approximately 432 miles ( 695 km) east

- north east of the lease are a.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due
to the distance and the difference in water depth

. Near

- bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume

up onto the continental shelf

.



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

T his section discusses species listed as endangered or threatened under the Endangered Species Act ( ESA ) . In addition, it includes all marine mammal species in the region, which are protected
under the Marine Mammal Protection Act ( MMPA ).

Endangered or thr eatened 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 Gulf of Mexico). Critical habitat is defined as (1) specific ar eas 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 are as outside the geographical area occupied by the species if the agency determines that the area itself is essential for

conservation. The National Marine Fisheries Service ( NMFS ) has jurisdiction for ESA

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

ESA

- listed birds and the West Indian m anatee.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan 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 mandated by the ESA, BOEMRE consulted NMFS and the USFWS on possible and potential impacts from the proposed leasing in the Gulf of Mexico on endangered/threatened species and their designated critical habitat (MMS

, 2007a

, b)

. A 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 Ar eas 2007

- 2012 are not likely to jeopardize the continued existence ofEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 31 threatened and endangered species under NMFS jurisdiction or destroy or adversely modify designated critical habitat. The informal ESA consultation with USFWS was concluded with a
lette r 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 both
NMFS and USFWS on 30 July 2010. The NMFS responded with a letter to BOEMRE on

24 September 2010 , and t he USFWS responded with a letter to BOEMRE on 27 September 201 0. 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
environment based on the results of the Natural Resource Damage Assessme nt ( NRDA ) process. The NRDA data have yet to be released , and the existing consultation remain s in effect (BOEM, 201 2b). The existing consultation recognizes that BOEM

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

BOEM

- authorized activities in the Gulf of Mexico.

Coastal endangered or threatened species that may occur along the northern Gulf Coast include
the West Indian manatee, Piping Plover, Whooping Crane, Gulf st urgeon, 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 (2007 b)
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 right whale, and sei whale) also have been reported from the Gulf of Mexico but are considered rare or extralimital there (Würsig et al., 2000). No critical habitat has been designated for these species in the Gulf of Mexico.



### C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the sperm whale ( Physeter macrocephalus )

. Resident populations of s perm whales occur within the
Gulf of Mexico. A species description is presented in a recent lease sale EIS (MMS, 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a “strategic stock” (defined as a stock that may have unsustainable human

- caused impacts) by NOAA Fisheries (Waring

et al., 2012 ). No critical habitat for the sperm whale has been de signated 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,East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 32 groups of sperm whales sighted in the Gulf of Mexico during the MMS

- funded Sperm Whale

Seismi c Study (SWSS) consisted of mixed

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

- tracked individuals suggest that this area of the Gulf continental slope is within the home range of the Gulf of Me xico population (within the

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

IPFs potent ially affecting sperm whales include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill (WCD). Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts o n 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 impediment to recovery

, ” a nd include fisheries interactions, anthropogenic noise, vessel interactions, contaminants and pollutants, disease, injury from marine debris, research, predation and natural mortality, direct harvest, competition for resources, loss of prey base due to climate change and ecosystem change, and cable laying.

In the Gulf of Mexico , the impacts from many of these threats are identified as either low or
unknown ( BOEMRE, 2011 a ; BOEM, 2012 b).



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

Noise from routine drilling activities has the potential to disturb sperm whales. Sperm whales appear to have good low

- frequency hearing, but the available data do not indicate a consistent response to anthropogenic noise (Jochens et al., 2008). Noise intensity associated with drilling is relatively weak, and the noise exposure of an individual animal would be transient. There are
other OCS facilities and activities near the lease area

, and the region as a whole has a large
number of similar noise sources. Due to the limi ted 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 th e 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 t o produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 2007).

Drilling rig lighting and rig presence are not identified as IPF s for sperm whales in recent lease sale EISs (M MS, 2007b, 2008; BOEM, 2012a, b ) or the NMFS (2007) Biological Opinion.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a ). Data concerning the frequency of vessel strikes are presented in a recent lease sale EISEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 33 (MMS, 2007b). To reduce the potential for vessel strikes, the BSEE and BOEM issued

NTL 2012

- JOINT

- 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

o f any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a distance of 91 m (300 ft) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less

, when safety permits

, when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm wha les.

NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales . With implementation of the mitigation measures in NTL 2012

- JOINT

- G01 , NMFS concluded that the likelihood of collisions between vessels and sperm whales would be red uced to insignificant levels. NMFS concluded that the observed avoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, or have any consequences at the population level

. With implementation of the vessel strike avoidance measures requirement to maintain a distance of 9 1 m ( 300 ft) from sperm whales,
the NMFS concluded that th e potential for harassment of sperm whales would be reduced to
discountable levels.

Helicopter traffic also has the potential to disturb sperm whales. Smultea et al. (2008) documented responses of sperm whales offshore Hawaii to fixed wing aircraft flying at an altitude of 245 m (800 ft). A reaction to the initial pass of the aircraft was observed during

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

360 m (1,180 ft) lateral distance from the aircraft. Additional reactions were seen when aircraft
circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by
the aircraft were short

- term and probably of no long

- term biological significance.

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

et al., 2008), the NMFS (2007) and BOEM (2012 d ) concluded that t his altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impac ts are expected

.


### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent lease
sale EISs (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012 a, b ) and by NMFS (2007) . Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

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

.
The probability of a fuel spill will be mi nimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will mitigate and lessen the potential for impacts on sperm whales. Given theEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 34 open ocean lo cation of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

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

, depending on sea state and weather conditions.

Direct physical and phy siological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [ MMC ] , 2011 ). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of sperm whales, no signific ant impacts would be expected.



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

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012 a,b, d ) and by NMFS (2007)

. For this EP , there

are n o 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, no ise, and dispersants) (MMC, 2011 ). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Be havioral responses can include displacement of animals from prime
habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or
patterns

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

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

- JOINT

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



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

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

Manat ee sightings in Louisiana have increased as the species extends its presence farther west of Florida in the warmer months (Wilson, 2003). A species description is presented in a recent lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill (WCD). A small fuel spill in the lease area would be unlikely to affect manatees, as the leaseEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 35 area is approximately 119 miles ( 192 km) from the nearest shoreline ( Texas ). As explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. Compliance with NTL 2012

- BSEE -G01 will minimize the potential for
marine debris

- rel ated impacts on manatees.



### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees

, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001).

To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 20 12

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species

, and requires operators to report sightings of any injured or dead protected species. Compliance with NTL 2012

- JOINT

- G01 will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic also has the potential to disturb manatees. Rathbun (1988) reported that manatees were disturbed more by helicopters than by fixed

- wing aircraft; however, the helicopter was flown at relatively low altitude s of 2 0 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 sensitiv e habitats such as wildlife refuges and park properties. In addition, guidelines and regulations specify that helicopters maintain an altitude of 305 m ( 1,000 ft)
within 91 m ( 300 ft) of marine mammals (BOEM, 2012a, d ). This mitigation measure will

minimi ze 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,

no ise, and dispersants) (MMC, 2011). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes;
inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of
social structure

, changing prey availability and fora ging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

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

- JOINT

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

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 36 

### 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.

Because of 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 into contact with any project activities, either routine operations or accidents . NMFS did not include any of these mysticete whales as affected species in its Biological Opinion (NMFS, 2007)

. Potential impacts are analyzed in recent lease sale EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b, d), and those analyses are incorporated by reference. If any of these whales were present in the area, potential imp acts would be the same as those discussed below in
Section C.3.4

.



### C.3.4 Non

- Endangered Marine Mammals (Protected)

Excluding the seven endangered species that have been cited previously, there are 22 additional species of marine mammals that may be found in the Gulf of Mexico

, 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 presented in a recent lease sale EIS (MMS, 2007b).

Myst icete 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

acutorostrata ) is considered rare in the Gulf of Mexico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it is possible that Bryde’s whales could occur in the lease area.

Dwarf and pygmy sperm whales

. At sea, it is difficult to differentiate dwarf sper m whales ( Kogia sima ) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as Kogia spp. Both species have a worldwide distribution in temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mullin et al., 1991). Either species could occur in the
lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked whale ( Ziphius cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon europaeus ). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked
whale is the mo st common and Sowerby’s is extralimital. Due to the difficulties of at

- sea identification, beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undifferentiated complex ( Mesoplodon spp. and Ziphius spp .). InEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 37 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 speci es 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 )

, short

- finned pilot whale ( Globicephala 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 common non

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

Bottlenose dolphins

IPFs potentially affecting non

- endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents –a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on marine mammals due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of marine mammals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potent ial for marine debris

- related impacts on marine mammals. . Bottlenose dolphin populations in the northern Gulf of Mexico are separated by the NMFS into 37 geographically distinct population units, or stocks, for management purposes (Waring et al., 2012). NMFS (2013) has proposed to classify the Gulf of Mexico Northern Coastal Stock, Western Coastal Stock, and all 32 of the Bay, Sound, and Estuarine Stocks as strategic stocks, based primarily on the occurrence of an " unusual mortality

event " of unprecedented size and duration (which began in February 2010 and is ongoing) that has affected these stock areas. Carmichael et al. (2012) hypothesized that the unusual number
of bottlenos e dolphin strandings in the northern Gulf of Mexico during this time may have been associated with environmental perturbations including sustained cold weather and the Macondo spill in 2010 as well as large volumes of cold freshwater discharge in the early months
of 2011.



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

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use higher freq uency sounds than th ose produced by OCS drilling activities (Richardson et al., 1995). Noise intensity associated with drilling is relatively weak, and the noise exposure of an individual animal would be transient. There are
other OCS facilities and acti vities near the lease area

, and the region as a whole has a large number of similar sources. Due to the limited scope and short duration of drilling activities , this project would represent a small temporary contribution to the overall noise regime

, and a ny short

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

Drilling rig lighting and rig presence are not identified as IPF s for marine mammals in recent lease sale EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a ; BOEM, 2012a ,b, d ).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 38 

### Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals

, and there is also a risk of
vessel strikes. Data concerning the frequency of vessel strikes are presented in a previous lease
sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, BSEE and BOEM issued

NTL 2012

- JOINT

- G0 1 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow dow n or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Vessel operators and crews are required to attempt to
maintain a distance of 91 m (300 ft) or greater when wha les are sighted and 45 m (150 ft) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direction until the ce tacean has left the area. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel

, when safety permits. Compliance with

NTL 2012

- JOINT -G 01 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). Howev er, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. In addition, guidelines and regulations specify that helicopters maintain an altitude of 1,000 ft (305 m) within 300 ft (91 m) of marine mammals (BOEM, 2012a, d ). This altitude will minimize the potential for disturbing marine mammals , and no significant impacts are expected ( BOEM, 2012a, d ).



### Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b ), and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For this EP , there are no unique site

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

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

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

. Given the open ocean location of the lease area, the limited duration of a small spill and response efforts, it is expected that any impacts would be brief a nd 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 andEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 39 noise of response vessels and aircraft (MMC, 2011 ). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significan t impacts would be expected.



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

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

, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b )

. For this EP , there are no unique site

- specific issues

. Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC,

201 1 ). Direct physical and physiological effects can include skin ir ritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat

, disruption of social structure

, changing prey availability and foraging distribution and/or patterns

, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 201 1 ).

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

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

.



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

F ive species of endangered or threatened sea turtles may be found n ear the lease area.
L eatherback ( Dermochelys coriacea ), Kemp's ridley ( Lepidochelys kempii ), and hawksbill ( Eretmochelys imbricata ) turtles are endangered . The loggerhead turtle ( Caretta caretta ) is currently a threatened species ; however, in March 20 10

, 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 Section 7 consultation under the current Five

- Year Program. As a res ult 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 letter 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 c urrently remain s in effect (BOEM, 201 2b).

BOEMRE (2011a) and BOEM (201 2b) reexamined the impacts analys es 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 foreseeableEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 40 cases, exposure to hydrocarbons persisting in the sea following the dispersal of an oil slick will

resu lt 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, hawk sbill, 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 areas, including the lease area, where they may be
associated with Sargassum and other flotsam.

Sea turtle nesting in the northern Gulf of Mexico can be summarized by species as follows:

• Loggerhead turtles – Loggerheads nest in significant numbers along the Florida Panhandle and, to a lesser extent, from Texas through Alabama ( BOEM, 2012d ) . The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the

Breton NWR ;

• Green and leatherback turtles – Green and leatherback turtles infrequently nest on
Florid a Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 201 3 );

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

Tamau lipas, Mexico (NMFS et al., 2011 ). Kemp’s ridley turtles typically do not nest anywhere near the project area, although there have be en occasional reports of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

• Hawksbill turtles – Hawksbills typically do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents – a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on sea turtles due to rapid
di spersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on sea turtles.



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

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disruption and temporary or permanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced during routine operations. Helicopters and s ervice vessels may also affect sea turtles due to machinery noise and/or visual disturbances. The most likely impacts would be short

- term behavioral changes such as diving and evasive swimming, disruption of activities, or departure
from the area. Due to the limited scope and short duration of drilling activities , these
short

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

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witheringt on, 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 structur es on sea turtles are insignificant.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 41 

### 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 period s of inclement weather. To reduce the potential for vessel strikes, BSEE and BOEM issued NTL 2012

- JOINT -G01 , which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are

si ghted, vessel operators and crews are required to attempt to maintain a distance of 45 m (150 ft) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 213 m (700 ft) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are expected.



### Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b ) and the NMFS Biological Opinion (NMFS, 200 7)

. 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, implem entation of Anadarko ’s OSRP is expected to

minimize potential impacts on sea turtles. EP Section H provides detail on spill response

measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to o ccur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and 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 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 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 119 miles ( 192 km) from the nearest shoreline ( Te xas ). As explained inEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 42 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 r esult 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 result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired movement and normal bodily functions (NMFS, 2007).

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

- JOINT

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

.



### C.3. 6 Piping Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result of hunting, habitat loss and modification, predat ion, 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 inv ertebrates 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 ( BOEM, 2012d ).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 43

Figure 3. Location of selected environmental features in relation to the lease area.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 44 A large oil spill (WCD) is the only IPF potentially affecting Piping Plovers. There are no IPFs associated with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in
Section A.9.2 ).



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

Th e lease area is 119 miles (192 km) from the nearest shoreline s inhabited by Piping Plovers ( Figure 3 ). The revised OSRA results (BOEMRE, 2011a; BOEM, 2012b) summarized in
Section A.9.3 ( Table 3 ) predict that during the spring there is a 18 % probability that an oil spill
from the lease area wou ld reach a shoreline designated as critical habitat for the Piping Plover
within 10 days. Plovers could physically oil themselves while foraging on oiled shores or secondarily contaminate themselves through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some death s of Piping Plovers could occur, especially if spills occur during winter months when plovers are most common along the coastal Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill cleanup. Anadarko has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP.



### C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership, 2010). One population winters along the Texas coast at Aransas NWR and
summers at Wood Buffalo National Park in Canada ; 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 agricultura l fields (USFWS, 2007). About 9,000 ha (22,240 ac) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species

. A species description is presented in recent lease
sale EIS s ( BOEM, 2012a ,d). A large oil spill (WCD) is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would also be unlikely to affect Whooping Cranes,
due to the distance from Aransas NW R. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up

. 

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

A large oil spill is unlikely to affect Whooping Cranes as the lease area is appro ximately
140 miles ( 225 km) from its critical habitat designated in the Aransas NWR . T he revised
OSRA modeling (BOEM, 201 2b ) predicts that there is a 5 % or less probability that an oil spill originating in the lease area would reach the Aransas NWR within 30 days and a 10 % probability of oil reaching that area in 120 days

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 45 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 shellf ish, frogs, and fishes . It is possible that some Whooping Crane deaths could occur. In the event of a spill, Anadarko would work with the applicable State and Federal agencies to prevent impacts from a spill

.



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

The Gulf stu rgeon ( 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 u pstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from Lake Borgne, Louisiana (St. Bernard Parish) t o Suwannee Sound, Florida (Levy County) (NMFS, 2010 b) ( Figure 3 )

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

.
A large oil spill (WCD) is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in
Section A.9.2 ).



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

Potential spill impacts on Gulf sturgeon are discussed in recent lease sale EISs ( MMS, 2007b,

2008 ; BOEMRE, 2011a; BOEM, 2012 b ) and by NMFS (2007)

. For this EP , there are no unique
site

- specific issues with respect to this species.

The lease area is approximately 320 miles ( 515 km) from the nearest Gulf sturgeon critical
habitat. The revised OSRA modeling (BOEM, 201 2b ) predicts that a spill in the lease area has

0.5 % or less probability of contacting any coastal areas inhab ited by Gulf sturgeon within

120 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petr oleum products through the gills. Based on the life history of this species, subadult and adult Gulf sturgeon would be most vulnerable to an estuarine or marine oil spill, and would be vulnerable only during the winter when this species is foraging in est uarine and shallow marine habitats (NMFS, 2007).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 46 

### 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 approximately 89,621 ha (221,459 ac ) of coastal habitat; and the Ten Thousand Islands/Everglades Unit, which comprises approximately 250,506 ha ( 619,013 ac ) of coast al
habitat. The two units are located along the southwestern coast of Florida between Charlotte Harbor and Florida Bay.

A large oil spill (WCD) is the only IPF potentially affecting smalltooth sawfish

. There are no IPFs associated with routine project activities that could affect these fish. A small fuel spill in the lease area would be unlikely to affect smalltooth sawfish because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

Potential spill impacts on smalltooth sawfish are similar to those discussed for other coastal and estuarine species in recent lease sale EISs ( MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a ) and by the NMFS (2007) in its Biological Opinion. For this EP , there are no unique site

- specific issues with respect to smalltooth sawfish

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



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

Four subspecies of endangered beach m ouse ( Peromyscus 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 critical habitat combined for all four subspecies . Species descriptions are provided in a rece nt lease sale EIS (MMS, 2007b)

.
A large oil spill (WCD) is the only IPF potentially affecting beach mice. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill in
the lease area would not affect beach mice because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

Potential spill impacts on beach mice are discussed in recent lease sale EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a ). For this EP , there are no unique site

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

.

Th e lease area is about 438 miles ( 704 km) west

- south west from the nearest beach mouse
critical habitat . The revised OSRA modeling summarized in Section A.9.3 predicts that a spill inEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 47 the lease area has a less 0.5 % probability of reaching either the Alabama or Florida shorelines inhabited by beach mice within 120 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subseq uent infection; matting of fur; irritation of sweat glands, ear tissues, and throat tissues; disruption of sight and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup. However, any such impacts are unlikely due to the distance from shore and response actions that would occur in the event of a spill.



### C.3.11 Elkhorn Coral (Endangered)

Elkhorn coral ( Acropora palmata ) is found primarily in shallow waters with temperatures ranging between 26°C and 30°C (79 °F and 86°F) and significant water movement. Elkhorn coral
was once one of the most abundant coral species in waters ranging from 1 to 5 m (3.3 to 16 ft) deep in tropical and subtropical waters. In the northern Gulf of Mexico , e lkhorn coral has been found within the coral cap region of the Flower Ga rden Banks National Marine Sanctuary ( Flower Garden Banks National Marine Sanctuary , 2011).

There are no IPFs associated with routine project activities that could affect this species in the
northern Gulf of Mexico

. A small fuel spill would not affect elk horn coral colonies because the oil would float and dissipate on the sea surface. A WCD would be unlikely to affect the coral cap region of the Flower Garden Banks because of the water depth of the area. 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 Marine Birds

Marine birds include seabirds and other species that may occur in the pelagic environment of the project area (Cla pp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore over the open ocean, except during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shor ebird s may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the distance from shore. For a discussion of shorebird s and coastal nesting birds, see Section C.4.2

.

Seabir ds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm

- petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, f our ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Sooty Tern, Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); and permanent resident species (Laughing Gulls, Royal Terns, Bridled Terns) (Hess and Ribic, 2000).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 48 Common seabird species include Wilson’s S torm -P etrel ( Oceanites oceanicus ) , Magnificent Frigatebird ( Fregat a magnificens ), Northern Gannet ( Morus bassanus ), Masked Booby ( Sula dactylatra ), Brown Booby ( Sula leucogaster ), Cory’s Shearwater ( Calonectris diomedea ), Greater Shearwater ( Puffinus gravis ), and Audubon’s Shearwater ( Puffinus lherminieri ). Seabirds

are distributed Gulf

- wide and are not specifically associated with the lease area.

Relationships with hydrographic features were found for several seabird species, possibly due to effects of hydrography on nutrient levels and productivity of surface waters where birds forage.
The GulfCet II study did not estimate bird densities; however, Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/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 temporary shelter from inclement weather (Russell, 2005). Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate
around these structures.

IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents - a small fuel spill and a large oil spill ( WCD ) . Effluent discharges are likely to have negligible impacts on the birds due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for
marine debris

- related impacts on birds.



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

Birds that frequent 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 s tructures has been reviewed extensively, and the mechanisms involved in rig collisions appear to be similar. In some cases, migrants simply do not see a part of the rig until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans

- Gulf migrant species, and most of the migrants that stop over on rigs probably benefit from their stay, particularly in spring (Russell, 2005). Due to the limited scope and short duration of drilling activities described in this EP, any impacts on populations of either seabirds or trans

- Gulf migrant birds are not expected to be significant.

A study in the North Sea indicated that rig lighting causes circling behavior in various birds, especially on cloudy nights; 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 Mexico also noted the phenomenon but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in the Gulf of Mexico v ersus the North Sea. In laboratory experiments, Poot et al. (2008) found the magnetic compass of migratory birds to be wavelength dependent. M igratory birds require light from the blue

- green part of the spectrum for magnetic compass orientation,East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 49 whereas red light (visible long

- wavelength) disrupts their magnetic orientation. They designed a field study to test if and how changing light color influenced migrating birds under field
conditions. During field studies they found that nocturnally migrating birds were disoriented and attracted by red and white light (containing visible long

- wavelength radiation), whereas they were clearly less disorien ted by blue and green light (containing less or no visible long

- wavelength radiation) ( Poot et al., 2008 ). Due to the limited scope and short duration of drilling activities proposed in this EP

, lighting impacts, collisions

, or other adverse effects are

u nlikely, 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 exper ience, at most, only short

- term behavioral disruption

, and the impact would not be significant.



### Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b ). 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 spill response measures. Given the open ocean location of the lease area, the duration of a small spill and oppor tunity for impacts to occur would be very brief.

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

, depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of
toxic fumes. Due to the limited ar eal extent and short duration of water quality impacts from a small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.



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

Potential spill impacts on marine and pelagic birds are discussed in recent EISs (MMS, 2007b, 2008; BOEMRE, 2011a; BOEM, 2012a,b ). For this EP , there are no unique site

- specific issues with respect to spill impacts on these animals.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 50 BOEM 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 alter the potential impact s on marine and pelagic birds ( BOEMRE, 2011 a ; BOEM, 2012 b ).

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

- petrels, shear waters, and jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/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 Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic species such as the Northern Gannet

, Magnificent Frigatebird, and Masked Booby ( USFWS, 2011 ). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.



### C.4.2 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 Sandwich Tern, Wi lson’s Plover, Black Skimmer, Forster’s Tern,
Gull

- Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in recent lease sale EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM,

2012a ).

The Brown Pelican ( Pele canus occidentalis ) was delisted from Federal endangered status in 2009 (USFWS, 2010c). However, this species remains endangered on the Louisiana list of Endangered Species (Louisiana Department of Wildlife and Fisheries, 2013), is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 20 05 ) and as a species of special concern by the State of Florida (Florida Fish and Wildlife

Conservation Commission, 201 3). Brown Pelicans in habit coastal habitats and forage within both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur in deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population of Brown Pelicans live s in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010 b ).

The Southern Bald Eagle ( Haliaeetus leucocephalus ) was delisted f rom its threatened status in
the lower 48 states on 28 June 2007. The Bald Eagle is a terrestrial raptor widely distributed across the southern U.S., including coastal habitats along the Gulf of Mexico. The Gulf 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 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 shorebird s or coastal nesting birds, as the lease area is 119 miles ( 192 km) from theEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 51 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 break ing up. Compliance with NTL 2012

- BSEE

- G01 will minimize the potential for marine debris

- related impacts on shorebirds.



### Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas n ear Port Fourchon and Houma

, Louisiana, where shorebird s and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vesse l traffic may disturb some foraging and resting birds. Flushing distances vary between species and between individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel pathways; known distances are from 2 0 to 49 m (65 to 160 ft) for personal watercraft and 23 to 58 m (75 to 190 ft) for an outboard

- powered boat (Rodgers and Schwikert, 2002). Flushing distances may be similar or less for the support vessels to be used for Anadarko’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreline, so disturbances to nesting birds, eggs, and chicks is not expected. Vessel operators will use designated navigation channels and comply with posted speed and wake restrictions while transiting sensitive inland
waterways. Due to the limited scope and short duration of drilling activities, any short

- term impacts are not expected to be biologically significant to coastal bird populations.

Ai rcraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances for some species (Bélanger and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91

- 36D recommends that pilots maintain a minimum a ltitude of 610 m (2,000 ft) when flying over

noise

- sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. This is greater than the distance (slant range) at which aircraft overflights have been reported to
cause behavi oral 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 Ma condo spill provide additional information about the species of coastal birds that may be affected in the event of a catastrophic spill of a similar nature and duration. This information supplements the analysis presented in the lease sale EIS (MMS, 2007b ). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds have been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, over 2,000 oiled birds have been collected alive and abo ut 1,200 released (NMFS, 2010 c ). According
to the USFWS (2011)

, bird species that have been treated for oiling include the following:

• Brown Pelican

• White Pelican

• Masked Booby

• Magnificent Frigatebird

• Laughing Gull • Herring Gull

• Northern Gannet

• Black Crowned Night Heron

• Tri

- colored Heron

• Green HeronEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 52 • Cattle Egret

• Snowy Egret

• Reddish Egret

• Least Bittern

• Common Tern

• Royal Tern

• Caspian Tern

• Sandwich Tern

• Forster ’ s Tern

• Black Tern

• Gull

- billed Tern

• Least Tern • Black Skimmer

• Black Oystercatcher

• White Ibis

• Roseate Spoonbill

• Willet

• Sanderling

• Dunlin

• Semipalmated Sandpiper

• Killdeer

• King Rail

• Clapper Rail

• Virginia Rail

According to the USFWS (2010d), species with the largest numbers of dead oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern, unidentified Gull, and unidentified Tern. There are no reports of Bald Eagle oiling.

While the M acondo spill had direct and indirect impacts to coastal and marine birds, it is premature to conclude impacts over a long period (BOEM, 2012 b ). M odeling of Macondo spill related bird impacts is underway by NRDA

, but results have not yet been released.

An tonio et al. (2011) modeled bird

- mortality from the Macondo spill showing cumulative carcass numbers and mortality rate increasing exponentially from the start of the Macondo spill until the mortality rate began to decline after the 97th day of the spill

. Note that the collected animals would be a small subset of the total number of impacted birds and therefore, the collected animals would represent an underestimated measure of the overall impact of the
Macondo event (BOEM

, 2012 b ).

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 wat er repellency of feathers and can cause hypothermia in the right conditions. As birds groom themselves, they can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an oiled adult sits on the nest.

As noted above, the Brown Pelican was rec ently removed from the Federal endangered species list. Over 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These data indicate that Brown Pelicans may be particularly at risk of oiling in
the event of a c atastrophic spill reaching coastal waters. Issues for Brown Pelicans include direct contact with oil, disturbance by cleanup activities, and long

- term habitat contamination.



## C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and R essler (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 mostEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 53 oli gotrophic in the world’s oceans. Superimposed on this low

- productivity condition are productive “hot spots” associated with entrainment of nutrient

- rich Mississippi River water and mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an important role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs a nd larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents -a small fuel spill and a large oil spill ( WCD).



### Impacts of Drilling Rig Pre sence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a
fish

- attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994 ; MMS, 2000, 2007b, 2008 ). This FAD effect could possibly enhance the feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are
considered minor.



### Impacts of Effluent Discharges

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but should be diluted rapidly to undetectable levels within tens to
hundreds o f meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. Deck drainage from contaminated areas will be passed through an
oil

- and

- water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but should be diluted rapidly to
undetectable levels within tens to hundred s of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water

, are expected to be diluted rapidly and have little or no impact on water column biota.



### Impacts of Water Intakes

Seawater will be drawn from the ocean for once

- through, noncontact cooling of machinery

on the drilling rig. R ig s considered for use in this EP ar e not “new” facilit ies as defined by the NPDES permit and therefore are not subject to the cooling water intake regulations for Phase III
facilities under Section 316(b) of the Clean Water Act

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 54 The intake of seawater for cooling water will entrain plankton . The low intake velocity should allow most strong

- swimming juvenile fishes and smaller adults to escape entrainment or impingement. However, drifting plankton would not be able to escape entrainment with the exception of a few fast

- swimming larvae of certain taxonomic groups. Those organisms entrained may be stressed or killed, primarily through changes in water temperature during the route from cooling intake structure to discharge structure and mechanical damage (turbulence in pumps and condensers). Due to the limited scope and short duration of drilling activities , any short

- term impacts of entrainment are not expected to be biologically significant to plankton or ichthyoplankton populations.



### Impacts of a Small Fuel Spill

Potential spill impacts on f isheries resource s are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a, d). F or this EP , there are no unique site

- specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will mitigate the potential for impacts on pelagic communities

, including ichthyoplankton. EP Section H provid es detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

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

, dependin g on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, and nekton. Due to the limited areal extent and short duration of water quality impacts, a small fuel spill would be unlikely to produce detectable impacts on pelagic communities.



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

A large oil spill could affect water column biota including phytoplankton, zooplankton, ichthyoplankton , and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larv ae of fishes are especially vulnerable to oiling because they inhabit the upper layers of the water column, and they will die if exposed to certain toxic fractions of spilled oil. Impacts potentially would be greater if local

- scale currents retained planktonic larval assemblages (and the floating oil slick)
within the same water mass.



### C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson

- Stevens Fishery Conservation and Management Act, as amended, Federal agencies are required to consult onEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 55 activities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fishery Management Counci ls.

The BOEM (201 2b ) has reexamined the analysis for fish resources and EFH presented in recent lease EISs (MMS, 2007a,b) , in consideration of the Macondo event. No substantial new information was found that would alter the impact conclusions for fish resources and EFH presented in MMS (2007a,b).

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management Plans for corals and coral reefs, shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). T he EFH for most of these GMFMC

- managed species is on the continental shelf in waters shallower than
183 m (600 ft). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps. EFH for corals and coral reefs includes some shelf

- edge topog raphic features on the Texas

- Louisiana OCS, the nearest of which are located approximately 37 miles ( 60 km) north

- northeast of the lease area

. Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for w hich EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS.

Highly migratory species with EFH at or near the lease area include the following species and life stages (NMFS, 2009):

• Atlantic bluefin tuna (spawn, eggs, larvae, adults)

• Blue marlin (juveniles, adults)

• Longbill spearfish (juveniles, adults)

• Oceanic whitetip shark (all) • Skipjack tuna (spawn, adults)

• Swordfish (larvae, juveniles)

• 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 o f 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 Canadian coasts, followed by migration to the Gulf of Mexico to spawn in Apr il, May, and June (NMFS, 2009).

On 27 May 2011, after an extensive scientific review, NOAA announced that Atlantic bluefin tuna currently do not warrant species protection under the ESA

. However, NOAA did classify
the bluefin tuna as a species of concern ; however, effectively placing bluefin tuna on a watch list as the agency awaits new data on the impact of a stricter international management regimen

.

A new amendment to the original EFH Generic Amendment was finalized in 2005 (GMFMC, 2005). One of the most significant proposed changes in this amendment reduced the extent of EFH relative to the 1998 Generic Amendment by removing the EFH description and
identification from waters between 100 fathoms and the seaward limit of the Exclusiv e Economic Zone ( EEZ )

. The Highly Migratory Species Fisheries Management Plan was amended

in 2009 to update EFH and HAPC to include the bluefin tuna spawning area ( NMFS , 2009).East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 56 There are current NTLs (2009

- G39 and 2009

- G40) that provide guidance and clari fication 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 BOEM’s Gulf of Mexico Region and NOAA’s Sout heastern Region. Some

EFH requirements may change with the new agreement. Until the new agreement is in place, the 1999 Programmatic Consultation with the elements described a bove will be followed ( BOEMRE, 2011 a ; BOEM, 2012 b ).

Other HAPCs have been ident ified by the GMFMC (2005). These include the Florida Middle Grounds, Madison

- Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The Wes t Flower Garden Bank is the nearest HAPC to the lease area, located approximately 48 miles ( 78 km) to the north east

.
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 migrato ry pelagic fishes are considered minor.



### Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling muds and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous
d ischarges such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water. Impacts on water quality have been discussed previously. No significant impacts

on EFH for highly migratory pelagic fishes are expected from these discharges.



### Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope and short duration of drilling activities , any sh ort

- term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically significant.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations inclu ding fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will help diminish the potential for impacts on EFH. EP Section H provides
detail on spill response measures. Given the open ocean location of the lease area, the du ration of a small spill and opportunity for impacts to occur would be very brief.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 57 Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a, d)

. F or this EP , there are no unique site

- specific issues with respect to spill impacts.

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

, depending on sea state and weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, sw ordfishes, 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 ext ent of the affected area would represent a negligible portion of the HAPC.

A small fuel spill is not expected to affect EFH for corals and coral reefs

. T he nearest EFH is located approximately 37 miles (60 km) north

- northeast of t he lease area. A small fuel spill would float and dissipate on the sea surface and would not contact these features due to their depth

.


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

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a, d ). For this EP , there are no unique site

- specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially in the subsurface as well. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimp s , stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality and water column biota including phytoplankton, zooplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloor habitat for managed demersal fish and shellfish species.

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 pot ential for lethal or sublethal impacts on spawning tuna. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The topographic features located 37 mil es ( 60 km) north

- northeast of the lease area are designated as EFH under the corals and coral reefs management plan. An accidental spill would be unlikely to affect this area because a surface slick would not reach these features due to their depth

.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 58 

## C.6 A rchaeological Resources

C.6.1 Shipwreck Sites

The BOEM (201 2b ) 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 o f BOEM

- sponsored studies and industry surveys. Specifically, evidence of damage to significant cultural resources (i.e., historic shipwrecks) has been shown to have occurred because of an incomplete knowledge of seafloor conditions in lease areas >200 m ( 656 ft) deep that have been exempted from high

- resolution surveys. Since significant historic shipwrecks have recently been discovered outside the previously designated high

- probability areas (some of which show evidence of impacts from permitted activiti es prior to their discovery), a survey is now required for exploration and development projects.

The lease area is not on the list of OCS blocks with a high potential for historic shipwrecks (BOEM, 2012 c ). There were no indications of wrecks or other arch aeological resources detected during the site clearance survey ( as referenced in GEMS, 2012) . Anadarko will abide by the applicable requirements of NTL 2005

- G07, which stipulate that work be stopped at the project site if any previously undetected archaeological resource is discovered after work has begun until appropriate surveys and evaluations have been completed.

Because there are no shipwreck sites in the lease area, there are no routine IPFs that are likely to affect shipwrecks. I mpacts of a large oil spill (WCD) are the only IPFs considered. A small fuel spill would not affect shipwrecks because the oil would float and dissipate on the sea surface.



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

MMS (2007b) estimate d that a severe subsurface blowout could resuspend and disperse
sediments within a 300

- m (984

- ft) radius. Because there are no historic shipwrecks in the lease area, this impact would not be relevant.

Previous analyses (MMS, 2007a, 2008) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 1,100 m (3,600 ft), extending at least 22 miles ( 35 km ) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact
sh ipwreck 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 thei r 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 co ntact the BOEM Regional Supervisor, Leasing and Environment, within 48 hours of its discovery. Anadarko would cease all operations within

305 m (1,000 ft) of the site until the Regional Supervisor provides instructions on steps to take
to assess the site’ s potential historic significance and protect it.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 59 A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. 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 Present (B.P.) (Nelson and Bray, 1970). Sea level in the northern Gulf reached its present stand around 3,500 year s B.P. (Pearson et al., 1986).

During periods that the continental shelf was exposed above sea level, the area was open to habitation by prehistoric peoples. The advent of early man into the Gulf of Mexico region is currently accepted to be around 12,000 years B.P. (Aten, 1983). The sea

- level curve for the
northern Gulf of Mexico proposed by Coastal Environments, Inc. (CEI) suggests that sea level at 12,000 years B.P. would have been approximately 45 to 60 m (148 to 197 ft) 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 prehistoric sites dating after 12,000 years B.P. Because of inherent uncertainties in both the depth of sea level and the entry date of prehistoric man into North America, the MMS adopted the 60

- m (197

- ft) water depth as the seaward extent for archaeological site potential in Gulf of Mexico region

.

With a water depth of approximately 1,109 m (3,637 m)

, the wellsite s are well beyond the 60

- m (197

- ft) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill (WCD). A small fuel spill would not affect prehistoric archaeological resources because the oil would float and dissipate on the sea
surface.



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

Because prehistoric archaeological sites are not found in t he 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 prehistoric site along these shorelines it could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup ope rations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).



## C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northeastern Gulf of Mexico that may be affected by oil and gas activities
are de scribed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b, d ) and in a literature review by Collard and Way (1997). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. General ly, most of theEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 60 northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries.

Due to the distance from shore, the only IPF associated with routine act ivities in the lease area
that potentially may affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area relate to support vessel traffic . The support bases at Port Fourchon and Houma, Louisiana

, are not in wildlife refuge s or wilderness area s . Potential impacts of support vessel traffic are addressed briefly below.

A small fuel spill in the lease area would be unlikely to affect coastal habitats because the lease

ar ea is 119 miles ( 192 km ) from the nearest shoreline ( Texas ) . As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking

up.



### Impacts of Support Vessel Traffic

For OCS activities in gen eral, 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 operat ions, including crew boats and supply boats as detailed in EP Section K

, may have a minor incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and channels.



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

Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b, 2008 ; BOEMRE, 2011a; BOEM, 2012a,b, d ). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this EP , there are no unique
site

- specific issues with respect to coastal habitats.

The revised OSRA modeling summarized in Table 3 predicts that during spring there is a
30 % probability of oil from a spill in the lease area reaching sh orelines in Texas within 120 days,
and a 8% probability in s ummer of oil reaching Louisiana shorelines within 120 days.

The shorelines within the geographic range predicted by the OSRA modeling ( Table 3 ) include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered
areas behind the barrier islands and in estuaries. NWRs and other protected areas along the
coast are discussed in a recent lease sale EIS (MMS, 2007b) and Anadarko ’s OSRP. Coastal and near coastal wildlife refuges, wilderness areas , and State and National parks within the geographic range of the potential shoreline contacts after 120 days are presented in Table 6

.

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: BOEM , 2012 b).

County or Parish , State W ildlife Refuge, Wilderness Area, or State/National Park

Cameron County, Texas Lower Rio Grande Valley N ational W ildlife R efuge
Laguna Atascosa National Wildlife Refuge

Padre Island National Seashore

Isla Blanca Park Andy Bowie County Park

Texas State Park Laguna Madre Estuarine and Coastal Marine AreaTable 6. (Continued).

East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 61 County or Parish , State W ildlife Refuge, Wilderness Area, or State/National Park

Willacy County, Texas Lower Rio Grande Valley National Wildlife Reserve Laguna Atascosa National Wildlife Reserve

Padre Island National Seashore Laguna Madre Estuarine And Coastal Marine Area

Kenedy County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Kleberg County, Texas Padre Island National Seashore Laguna Madre Estuarine and Coastal Marine Area

Nueces County, Texas Laguna Madre Estuarine and Coastal Marine Area Mustang Island State Park Lake Corpus Christi State Park

Port Aransas Park

Mission

- Aransas National Estuarine Research Reserve

Aransas County, Texas Mission

- Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge

Goose Island State Park

Calhoun County, Texas Mission

- Aransas National Estuarine Research Reserve

Aransas National Wildlife Refuge
Matagorda Island State Park Guadalupe Delta W ildlife M anagement Area

Welder Flats Coastal Preserve

Matagorda County, Texas Big Boggy National Wildlife Refuge

Aransas National Wildlife Refuge

Mad Island W ildlife M anagement Area

San Bernard National Wildlife Refuge

Brazoria County, Texas San Bernard National Wildlife Refuge

Peach Point W ildlife M anagement 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 W ildlife M anagement Area

Ft. Anahuc Park

Anahuac National Wildlife Refuge

McFaddin National Wildlife Refuge Candy Abshier Wildlife Management Area Atkinson Island Wildlife Management Area

Chambers, Texas Anahuac National Wildlife Refuge McFaddin National Wildlife Refuge

Jefferson County, Texas McFaddin National Wildlife Refuge

Sea Rim State Park Murphree W ildlife M anagement Area

Texas Point National Wildlife RefugeTable 6. (Continued).

East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 62 County or Parish , State W ildlife Refuge, Wilderness Area, or State/National Park

Cameron Parish, Louisiana Sabine National Wildlife Refuge

Cameron Prairie National Wildlife Refuge

Lacassine National Wildlife Refuge

Little Pecan Island Natural Area

Peveto Woods Natural Area

Lower Neches W ildlife M anagement Area

Rockefeller W ildlife M anagement Area

Vermilion Parish, Louisiana Louisiana Rockefeller W ildlife M anagement Area Paul J. Rainey W ildlife M anagement Area

Iberia Parish, Louisiana Marsh Island Wildlife Management Area
Cypremort Point State Park Shell Keys National Wildlife Refuge

Terrebonne Parish, Louisiana Atchafalaya Delta Wildlife Management Area Mandalay National Wildlife Refuge Isles Dernieres Barrier Islands Refuge Point Au Chein Wildlife Management Area

Plaquemines Parish, Louisiana Salvador W ildlife M anagement Area

Jean Lafitte National Historical Park and Preserve

Delta National Wildlife Refuge

Pass -a- Loutre W ildlife M anagement Area

Breton National Wildlife Refuge

St. Bernard State Park

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil

- and

- water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist for several years as it slowly biodegrades and volatilizes.

Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 2.7 ha (6.7 ac) of wetl and vegetation will experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. E vidence of recovery, such a shoot production and regrowth, was noticed in heavily oiled areas along the Loui siana coast 1 year after the Macondo event (BOEM, 2012a). 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. Louisian a wetlands areEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 63 assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b ; BOEMRE, 2011a; BOEM, 2012b ).



## C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

BOEM has reexamined the analysis for recreationa l and commercial fishing presented 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 a ; BOEM, 2012 b).

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and

summer. 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 t ypically 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 tha t 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).

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 T exas and Louisiana. Due to the distance from shore, it is unlikely that recreational fishing activity is occurring in the lease area.

The only IPF s potentially affecting fisheries are drilling rig presence (including noise and lights)
and t wo types of pot ential accidents – 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 sn agged on the acoustic DopplerEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 64 current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident. Generally, longline fishers use radar and are
aware of offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic longlining is expected.

Because it is unlikely that any recreational fishing activity is occurring in the project area, no adverse impacts are anticipated. Other factors such as effluent discharges are likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H 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.

Pelagic longlining activities in the lease area, if any, could be inter rupted in the event of a small fuel spill. The area of the sea surface with diesel fuel on it would range from 0.5 to 5 ha (1.2 to 12 ac)

, depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of res ponse vessels operating in the lease area. A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

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

- specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill response measures. The 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

encompass ed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Gulf of Mexico EEZ.



### C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anad arko ’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 ocea n 119 miles ( 192 km) from the nearest shoreline ( Texas ) andEast Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 65 nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects.

A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).



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

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel involved in the incident and those responding to the spill. The drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, meteorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, including skin contact or breathing VOCs . Crude oil is a highly flammable material

, and any smoke or vapors from a crude oil fire can cause irritation, and in large quantities may pose a health
hazard.

Data from the Macondo spill provide r elevant 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,

itc hy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildlife

- cleaning workers. Personnel working on offshore vessels or providing direct oversight to o ffshore vesse ls, including USCG personnel, civilian contractors, and other responders who were exposed to oil and dispersants

, had a 7 to

12 times higher prevalence of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Preventi on, 2010b). Another potential occupational hazard for spill response workers in general was heat stress from work in a hot and humid environment. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of
acute exposure to hydrocarbons or 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 affec t employment and infrastructure. The project involves drilling with support from existing shorebase facilities in

Louisiana . No new or expanded facilities will be constructed, and no new employees are expected to move permanently into the area. The proj ect will have a negligible impact on socioeconomic conditions such as local employment, existing offshore and coastal infrastructure (including major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a sma ll fuel spill and a large oil spill (WCD) are addressed below.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially mitigate and reduce the potential for impacts. EP Section H 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.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 66 A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.



### Impacts of a Large Oil Spi ll (WCD)

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008 ; BOEM, 2012a,b ). For this EP , there are no unique site

- specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it could result in temporary employment as part of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, including service and support operations that are an important part of local economies.

In addition to the analys e s presented by MMS (2007b, 2008 ) an d BOEM (201 2b ), 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 o f 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- mont h period; this direct reduction in spending affected employment in the industries that supply the Gulf drilling industry and in all other industries affected by declines in consumer and business spending (Inter

- Agency Economic Report, 2010)

.



### C.8.4 Recreati on and Tourism

BOEM 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. No new information was found that would alter the potential impa ct s on recreation and tourism ( BOEMRE, 2011 a ; BOEM, 2012 b ).

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities due to the distance from shore. Compliance with NTL 2012

- BSEE

- G01 will minimize the chance of tras h or debris being lost overboard from the drilling rig and subsequently washing up on beaches.



### Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Anadarko ’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of
Anadarko ’s OSRP will potentially help mitigate and reduce the potential for impacts.

EP Section H 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 to affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area, and as explained in
Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 67 

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

Potential impacts of an oil spill on recreation and tourism are discussed in rece nt EISs (MMS, 2007b, 2008 ; BOEM, 2012a ). For this EP , there are no unique site

- specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on the
revised OSRA modeling (BOEM , 2012 b ) as summarized in Section A.9.3 ( Table 3 )

, there is a

30 % probability in spring of oil from a spill in the lease area reaching shorelines in Texas and a
8% chance in s ummer 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 estima ted the economic impact of the Macondo spill on tourism across the Gulf Coast over a three

- year period at $22.7 billion (Oxford Economics, 2010)

.



### C.8.5 Land Use

Land use along the northern Gulf C oast is discussed in recent lease sale EISs (MMS, 2007b, 200 8 ; BOEM, 2012a,b ). 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, will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fraction of the level of activity o ccurring at the shorebase s.

A large oil spill (WCD) is the only relevant IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.



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

The init ial 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 Mac ondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging
areas could be needed. These areas wou ld eventually return to their original use as the response is demobilized.



### C.8.6 Other Marine Uses

The lease area is located within Military Warning Area s W

- 602 and W

- 147E and Anadarko will comply with BOEM requirements and lease stipulations to avoid impacts on military vessels and aircraft operating in or near the lease site. There are existing wells and Anadarko pipelines within 610 m (2,000 ft) of the proposed wellsites (GEMS, 2012) and Anadarko will avoid these.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 68 There are no IPFs from routine project activities that are likely to affect other marine uses of the lease area. A large oil spill (WCD) is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses because spill response activities would be mainly within
the lease area and the duration would be brief.



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

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The
block is not located withi n any USCG

- designated fairway or shipping lane

. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Anadarko will comply with BOEM requirements and lease stip ulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure that no anchoring or seafloor

- disturbing activities occur near th e existing pipelines and flowlines.



## D. Environmental Hazards

D.1 Geologic Hazards

Site clearance letters prepared by GEMS (2012) concluded that the wellsites are free of any significant geological hazards and suitable for the proposed activities. Cautio n is advised when drilling through seafloor and buried faults. See EP Section C for supporting geological and geophysical information.



## D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed

activities. Ext reme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rigs under consideration for this project . High winds and limited visibility during a severe storm could disrupt support activitie s (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 b e adhered to.



## D.3 Currents and Waves

Metocean conditions such as sea states, wind speed, ocean currents, etc. will be continuously
monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed a ctivities. 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 could disrupt support acti vities (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.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 69 

## E. Alternatives

N o formal alternatives we re evaluated in this EIA for an EP . Ho wever, various technical and operational options

, including the location of the wellsite and the selection of a drilling unit, were considered by Anadarko in developing the proposed action.



## F. Mitigation Measures

The proposed action includes numerous mit igation measures required by laws, regulations, and

BOEM 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. Al l 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

• Carlyle Kalloo (Senior Scientist);

• M. John Thompson (Senior Scientist);

• Neal Phillips, Ph.D. (Senior Scientist);

• Deborah K. Fawcett (Project Scientist);

• Keith VanGraafeiland (GIS/Remote Sensing Specialist);

• Kristen L. Metzger (Library and Information Services Director ) ; and

• Kim Dunleavy (Technical Editor).



## I. References

Anderson, C.M. and R.P. LaBelle. 2000. Update of comparative occurrence rates for offshore oil spills. In: Spill
Science & Technology Bulletin, Vol. 6, No. 5/6, pp. 303

- 321. Elsevier Science Ltd., PII: S1353

- 2561(01)

00049

- 4. U.S. Minerals Management Service, Herndon, VA. Antonio, F.J., R.S. Mendes, and S.M. Thomaz. 2011. Identifying and modeling patterns of tetrapod verte brate mortality rates in the Gulf of Mexico oil spill. Aquatic Toxicology 105(1

- 2):177

- 179. Aten, L.E. 1983. Indians of the upper Texas coast. New York, NY: Academic Press. 370 pp.East Breaks Block 646 March 2013 Environmental Impact Analysis for Supplemental Exploration Plan Page 70 Barkuloo, J.M. 1988. Report on the conservation status of the Gulf o f Mexico sturgeon, Acipenser oxyrinchus desotoi. U.S. Department of the Interior, U.S. Fish Wildlif e Service, Panama City, FL.

33 pp. Bélanger, L. and J. Bédard. 1989. Responses of Staging Greater Snow Geese to Human Disturbance. Journal of
Wildlife Management 53:713

- 719. Biggs, D.C. and P.H. Ressler. 2000. Water column biology, pp. 141

- 187. In: Continental Shelf Associates, Inc. Deepwater Program: Gulf of Mexico Deepwater Information Resources Data Search and Literature Synthesis.
Volume I: Narra tive Report. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. OCS Study MMS 2000

- 049. Boehm, P., D. Turton, A. Raval, D. Caudle, D. French, N. Rabalais, R. Spies, and J. Johnson. 2001. Deepwater program: Literature review, environmental risks of chemical products used in Gulf of Mexico deepwater oil and gas operations. Volume I: Technical report. U.S. Department of the Interior, Minerals Management Service, Gulf of Mexico OCS Region, New Orleans , LA. OCS Study MMS 2001

- 011. 326 pp. Brooke, S., and W.W. Schroeder. 2007. State of deep coral ecosystems in the Gulf of Mexico region: Texas to the Florida Straits, pp. 271

- 306. In: S.E. Lumsden, T.F. Hourigan, A.W. Bruckner, and G. Dorr (eds.)

, The State of Deep Coral Ecosystems of the United States. NOAA Tech. Memo. CRCP

- 3. Silver Spring, MD. 365 pp.Bureau of Ocean Energy Management. 2011b. Bureau of Ocean Energy Management, Regulation and Enforcement Spills – Statistics and Summaries 1996

- 201 1. Website accessed 13 October 2011. http://www.boem.gov/search

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### SECTION 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 Reports previously submitted with Plan Control No: S-7363 and N-9591

 Site Clearance Letter included with this EP submittal (Covers East Breaks Block 646, Location EE and also East Breaks Block 646, Location EEE since within the same 500’ radius)

 

### Final Sale Package for Western Gulf of Mexico Lease Sale 171