UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - N-09600

Type - Initial Exploration Plan

Lease(s) - OCS-G31507 Block - 525 Mississippi Canyon Area

Operator - Shell Offshore Inc.

Subsea Wells A, B, C, D, and E

Not Found

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

should be addressed in an Environmental Assessment.

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

Karen Dunlap

Plan Coordinator Description -

Rig Type - Subject: From: January 9, 2012Shell Offshore Inc

. P. O. Box 61933
New Orleans, LA 70161

- 1933

United States of America

Tel +1 504 728 7215

Fax +1 504 728 6747 Telex http://www.shell.com/eandp

- en
Email Sylvia.bellone @shell.com

Public Information Copy

Sep tember 30

, 2011

Ms. Liz Peuler, Section Chief

Bu reau of Ocean Energy Management

1201 Elmwood Park Boulevard New Orleans, LA 70123

- 2394

Attn: Plans Group MS 5231

SUBJECT: Initial Exploration Plan

OCS

- G 31507

, Mississippi Canyon Block 525 Offshore, Louisiana and Alabama

Dear Ms. Peuler :

In compliance with 30 CFR 250.103 and NTLs 2008

- G04

, 2009

- G27 and 2010

- N06 , giving Exploration Plan guidelines,

Shell Offshore Inc (SOI) requests your approval of this Initial Exploration Plan to drill Well Locations A, B, C, D & E

. Depending on rig availability operations could commence as early as May 201 2

.

This Plan consists of a series of attachments describing our intended operations. The attachments we desire to be exempted from disclosure under the Freedom of Information Act are marked ―Confidential‖ and excluded from the Public Information Copies of this submittal. The cost recovery fee receipt of $ 17,210 ($3,442 for e ach SL) is attached to the Proprietary copy of the Plan.

Should you require additional information, please contact Tracy Albert at 504.728.4652 or m e as shown above.

Sincerely,

Sylvia A. Bellone

## SHELL OFFSHORE INC.

INITIAL EXPLORATION PLAN

for

OCS

- G 31507, Mississippi Canyon Block 525



# PUBLIC INFORMATION COPY

PREPARED BY:



## Tracy W. Albert Regulatory Specialist

504.728. 4652

tracy.albert@shell.com

### REVISIONS TABLE to PLAN N

- 9600 :

Date of Request Plan Section What was Corrected Date

Resubmitted 10/3/2011 Section 1 Section 2j

Section 6

Section9 Verify Well ―B‖ BHL (proprietary copy only)

Clarification for duration of spill Discuss ROV survey & verify well D location.

Add CGA as OSRO 10/6/2011

10/7/2011 Section 2j Re vised structure map (Proprietary copy only.) 10/7/2011 10/31/2011 N/A BOEM Requested full set of plan to deem complete 1 1 / 0 1/2011 11/ 08 /2011 Section 2J

Section 9

Section 18 WCD calculation

WCD comparison table

WCD number 12/14/2011INITIAL EXPLORATION PLAN

OCS

- G 31507
, MISSISSIPPI CANYON BLOCK 525

OFFSHORE, LOUISIANA

TABLE OF CONTENTS

SECTION 1 PLAN CONTENTS

SECTION 2 GENERAL INFORMATION

SECTION 3 GEOLOGICAL AND GEOPHYSICAL INFORMATION

SECTION 4 HYDROGEN SULFIDE

- H 2 S INFORMATION

SECTION 5 MINERAL RESOURCE CONSERVATION INFORMATION

SECTION 6 BIOLOGICAL, PHYSICAL AND SOCIOECONOMIC

INFORMATION

SECTION 7 WASTE AND DISCHARGE INFORMATION

SECTION 8 AIR EMISSIONS INFORMATION

SECTION 9 OIL SPILLS INFORMATION

SECTION 10 ENVIRONMENT AL MONITORING INFORMATION

SECTION 11 LEASE STIPULATIONS INFORMATION

SECTION 12 ENVIRONMENTAL MITIGATION MEASURES INFORMATION

SECTION 13 RELATED FACILITIES AND OPERATIONS INFORMATION

SECTION 14 SUPPORT VESSELS AND AIRCRAFT INFORMATION

SECTION 15 ONSHORE SUPPORT FACILITIES INFORMATION

SECTION 16 SULPHUR OPERATIONS INFORMATION

SECTION 17 COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION

SECTION 18 ENVIRONMENTAL IMPACT ANALYSIS (EIA)

SECTION 19 ADMINISTRATIVE INFORMATION

### Acronyms and Abbreviations

ABS American Bureau of Shipping

ACP Area Contingency Plan

ADDS Aerial Dispersant Delivery System

ADIOS Automated Data Inquiry for Oil Spills

APD Application for Permit to Drill

AUV autonomous underwater vehicle

bbl barrels

BOEM Bureau of Oc ean Energy Management

BOP blowout preventers

BPD barrels per day ( bbl/day )

BSEE Bureau of Safety and Environmental Enforcement

CCA Clean Caribbean & Americas

CFR Code of Federal Regulations

CGA Clean Gulf Associates

CH 4 methane

CO carbon monoxide

CO 2 carbon dioxide

COTP USCG Captain of the Port

CP Coastal Preserve

DOCD Development Operations Coordination

Document

DP dynamically positioned

EA Environmental Assessment

EDRC effective daily recovery capacity

EEZ Exclusive Economic Zone

EFH Essential Fish Habitat

EIA Environmental Impact Analysis

EIS Environmental Impact Statement

EP Exploration Plan

EPA Environmental Protection Agency

ESA Endangered Species Act

ESR Enhanced Surface Rendering

ESI Environmental Sensitivity Index

FAD fish

- attracting device

GB Garden Banks

GOM Gulf of Mexico

GMFMC Gulf of Mexico Fishery Management Council

H 2 S hydrogen sulfide

HAPC Habitat Area of Particular Concern

HSE health, safety, and environment

IMO International Maritime Organization

IPF impact

- producing factor

IRCS Incidence Response Command System

ISB In

- situ burning

ISO International Organization for Standardization

MARPOL International Convention for the Prevention of

Pollution from Ships

MC Mississippi Canyon MGD million gallons per day

MMBO million barrel s of oil

MMC Marine Mammal Commission

MMPA Marine Mammal Protection Act

MMS Minerals Management Service

MSRC Marine Spill Response Company

MWCC Marine Well Containment Company

NAAQS National Ambient Air Quality Standards

NCP National Contingency Plan

NEPA National Environmental Policy Act

NMFS National Marine Fisheries Service

NOAA National Oceanic and Atmospheric

Administration

NO

x nitrogen oxides

NPDES National Pollutant Discharge Elimination System

NPS National Park Service

NRC National Research Council

NTL Notice to Lessees

NWR National Wildlife Refuge

OCS Outer Continental Shelf

OCSLA Outer Continental Shelf Lands Act

OSAT Operational Science Advisory Team

OSRA Oil Spill Risk Analysis

OSRAM Oil Spill Risk Analysis Model

OSRL Oil Spill Response Limited

OSRB Oil Spill Response Barge

OSRO Oil Spill Removal Organization

OSRP Oil Spill Response Plan

OSRV Oil Spill Response Vessel

PAH polycyclic aromatic hydrocarbon

PM particulate matter

PSD Prevention of Significant Deterioration

R&D Research and development

ROV remotely operated vehicle

RRT Regional Response Team

SEAE Environmental Site Assessment

Shell Shell Offshore Inc.

SBM synthetic

- based mud

SEP Supplemental Exploration Plan

SO

x sulfur oxides

SP State Park

SWSS Sperm Whale Seismic Study

U.S.C Unites States Code

USCG U.S. Coast Guard

USDOI U.S. Department of the Interior

USEPA U.S. Environmental Protection Agency

VOC volatile organic compound

USFWS U.S. Fish and Wildlife Service

WCD worst case discharge

WCEP Whooping Crane Eastern Partnership

WMA Wildl ife Management AreaSECTION 1: PLAN CONTENT S

A. DESCRIPTION, OBJECTIVES & SCHEDULE

This Initial Exploration Plan ( EP /Plan ) with appendices, including an Environmental Impact Analysis (EIA) found in Section 18, describes the drilling activities Shell Offshore Inc. (Shell) plans to conduct with respect to OCS

- G

31507

, Mississippi Canyon Block 525

. The wells proposed in this P lan are A, B, C, D and E

. The wells will be drilled and temporarily abandoned (cement plug s and corrosion cap) until the wells are completed and developed under future plan s . If the well s are unsuccessful, they will be permanently plugged and abandon ed in accordance with BOEM regulations.

Shell‘s plan, as detailed in this EP, is to use a drillship , the M/V Noble Globetrotter or equivalent rig (the ―Rig‖), to drill up to five ( 5 ) new exploration wells in the Mississippi Canyon Area , Block 525 ( MC 525 ), located approximately 79 miles from the nearest coastline (Louisiana), 1 64 miles from the supply base at Port Fourchon, Louisiana, and 208 miles from the helicopter terminal at Amelia , Louisiana. Water depth s at the proposed well

surface locations are between 7

, 400‘ and 7

, 600‘ (Attachment 1 A ) . The drilling activities are planned to

commence on or about May 1, 201 2 and take last approximately 1 4 8 days for the first well and approximately 128 days for the other wells . The timeframe to complete the init ial drilling activities is an estimate based on the best available information regarding downhole conditions likely to be encountered while drilling each well

and not intended to be a limitation.

The proposed r ig is a dynamically position ed (D P ) d rillship and is equipped with state

- of

- the

- art drilling equipment and well control. It is a large

, self

- contained drilling vessel with acc ommodations for a crew which

includes quarters, galley and sanitation facilities. The r ig will comply with the requir ements in the Interim Final Drilling Rules. The drilling activities will be supported by the support vessels and aircraft as well as onshore support facilities as listed in Sections 14 and 15 of the EP. Shell has employed or contracted with trained

person nel to carry out its exploration activities. Shell is committed to local hire, local contracting and local purchasing to the maximum extent possible. Shell personnel and contractors are experienced at operating in

the Gulf of Mexico and are well versed i n all Federal and State laws regulating operations. Shell‘s employees and contractors share Shell‘s deep commitment to operating in a safe and environmentally responsible manner.

Shell, through its parent and affiliate corporations, has extensive experie nce safely exploring for oil and gas in the Gulf of Mexico. Shell will draw upon this experience in organizing and carrying out its planned MC 525 drilling program

. Shell believes that the best way to manage blowouts is to prevent them from happening.

Si gnificant effort goes into the design and execution of wells and into building and maintaining staff competence. In the unlikely event of a spill, Shell‘s Regional Oil Spill Response Plan ( OSRP ) updated August

2011

, is designed to contain and respond to a spill that meets or exceeds the WCD detailed in S ection 9 of this

EP . The WCD does not take into account potential flow mitigating factors such as well bridging, obstructions in wellbore, reservoir barriers, or early intervention. We continue to invest in Research and Development (R&D) to improve safety and reliability of our well systems. All operations will be conducted in accordance with applicable federal and state laws, regulations, and lease and permit require ments. Shell will have trained personnel and monitoring programs in place to ensure such compliance.

B. LOCATION

See attached location plat (Attachment 1B) and BOEM forms (Attachments 1 C through 1H )

.

C. RIG SAFETY AND POLLU TION FEATURES :

The r ig ( Noble Globetrotter or similar) will comply with all of the regulations of the American Bureau of Shipping (ABS), International Maritime Organization (IMO) and the United States Coast Guard (USCG). All drilling operations will be conducted under the provisions of 30 CFR, Part 250, Subpa rt D , and other applicable regulations and notices, including those regarding the avoidance of potential drilling hazards and safety and pollution prevention control. Such measures as inflow detection and well control, monitoring for loss of

circulation a nd seepage loss, and casing design will be our primary safety measures. Primary pollution prevention measures are contaminated and non

- contaminated drain system

, and oily water processing.DRAIN SYSTEM POLLUTION FEATURES

Drains are provided on the r ig in all spaces and on all decks where water or oil can accumulate. The drains are divided into two categories, non

- contaminated and contaminated. All deck drains are fitted with a removable strainer plate to prevent debris entering the system.

Deck Drainage from rainfall, r ig washing, deck washing, and runoff from curbs and gutters, including drip pans and work areas, are discharged depending on if it comes in contact with the contaminated or non

contaminated areas of the r ig.

1) Non

- contaminated Dr ains

Non

- contaminated drains are designated as drains that under normal circumstances do not contain hydrocarbons, and can be discharged directly overboard. These are mostly located around the main deck and outboard in places where it is unlikely that hyd rocarbons will be found.

Drains within 50 feet of a designated chemical storage area which uses the weather deck as a primary containment means shall be designated ―normally plugged.‖ An adequate number of drains around the rig shall be designated as ―n ormally open‖ to allow run

- off of rain water. Normally open drains shall have a plug located in a conspicuous area near the drain which can be easily installed in the event of a spill.

The rig‘s drain plug program consist at a minimum of a weekly check of all deck drains leading to the sea to verify that their status is as designated If normally open they shall verify that the drain is open and that the plug is available in the area. If normally closed they shall verify that the plug is securely instal led in the

drain.

In the event a leak or spill is observed, the event shall be contained (drain plug installation and / or spill kit deployment as appropriate) and reported immediately.

Rig personnel shall ensure that the perimeter kick

- plates on weath er decks are maintained and drain plugs are in place as needed to ensure a proper seal.

2) Contaminated Drains

Contaminated drains are designated as drains that contain hydrocarbons and cannot be discharged

overboard. When oil

- based mud is used for drilling it will be collected in portable tanks and sent to shore for processing.

3 ) Oily Water Processing

Oily water is collected in an oily water tank. It must be sep arated and not pumped overboard until oil

content is < 15 ppm. The sep arated oil is pumped to a dirty oil tank and has to be sent ashore for disposal. On board the mobile offshore drilling unit ( MODU ) an oil record log has to be kept according to instructions included in the log. Any and all pollution pans are subjected to a sheen test before being pumped out. If the water passes the sheen test then it is pumped over board. If it does not pass the sheen test then the water/oil mixture is pumped to a dirty oil tank and sent to shore for disposal. All waste

oil that is sent in to be disposed of is recorded in the MODU‘s oil log book.

All discharges will be in accordance with applicable EPA NPDES permits. See Section 18 of this Plan.

4 ) Lower Hull Bilge System

• The main bilge system is designed to drain the pontoons. There are Gould‘s electrically driven, self priming centrifugal pumps

- one for each main pump room. The aux pumps can be pump out with the bilge pump but has to be line d up manually from the main pump room.

• Bilge water is pumped overboard after a sheen test has been completed.

• The pontoon bilge pumps are operable from the Bridge, and have audible and visual bilge alarms set for high and low levels.

• Portable submersible pumps are carried onboard the rig to service all column void spaces and are also

use d for emergency bilge pump in the event of the main pump room flooding.• Alternate means of pumping the bilges in each pontoon pump room include the use of:

• The ballast system emergency bilge valve which is operated from the control panel.

• Portable submersible pumps

• Emergency bilge suction line connected directly to the ballast manifold. (Main Pump rooms only)

The Bilge pumps are manual/automatic type pumps. They are equipped with sens ors that give a high and a high

- high alarm. They are set to a point at which the water gets to a certain point they will automatically turn on to pump water out in order to keep flooding under control. The pumps are also capable of being put in manual mode in which they can be turned on by hand.

5 ) Emergency Bilge System

Main ballast pumps may also be used for emergency bilge pumping directly from the pump rooms via remotely actuated direct bilge suction valves on the ballast system. These valves will operate in a fully flooded compart ment. The ballast pumps can be supplied from the emergency switchboard.

6 ) Oily Water Drain/ Sep aration System

Oily water/engine room bilge water is collected in an oily water tank. It must be sep arated and not pumped

overboard until oil content is < 15 ppm. The sep arated oil is pumped to a dirty oil tank and has to be sent ashore for disposal. On board all drilling Units, an oil record log has to be kept according to instructions included in the log. The rig floor has two skimmer tanks and each is sub jected to a sheen test before pumping overboard to ensure environmental safety. All three anchor winch windlasses have skimmer tanks and are subjected to sheen tests before discharge as well

7 ) Drain, Effluent and Waste Systems

• The r ig‘s drainage syst em is designed in line with our environmental and single point discharge policies. Drains are either hazardous, i.e. from a hazardous area as depicted on the Area Classification drawings,

or non

- hazardous drains from nonhazardous areas.

• To prevent migra tion of hazardous materials and flammable gas from hazardous to non

- hazardous areas, the drainage systems are segregated.

• The r ig drainage systems tie into oily water sep arators that take out elements in the drainage that

could harm the environment. Thi s is part of Noble‘s initiative to be good stewards of the environment. The oily water sep arators divide the drainage system into these sections:

8 ) Rig Floor Drainage

The r ig floor has been outfitted with a Facet International MAS 34

- 3 sep arator. The se p arator has coalescent plates that remove the solids from the drainage, and the remaining drainage goes to a skimmer tank. From the skimmer tank it is drained to one of the column dirty oil tank systems where it is then sent through two

sep arators and cle aned further to reduce oil content to less than 15 ppm.

9 ) Columns #3 & 4

The drains on the decks and machinery spaces are sep arated at mid ship and directed to either the #3 or #4

columns. The sep arators in these columns go through three cycles of circulation and remove oil to less than

15 ppm, then discharge the clean product to sea.

1 0 ) Main Engine Rooms

• The engine rooms have their own drainage and handling system. The engine rooms are outfitted with a dirty oil tank and the drainage in the tank is processed through the sep arator, the waste from the

sep arator goes back to the dirty oil tank and the clean w ater (less than 15 ppm) goes overboard.

• The locations and models of the sep arators are as follows:

• Column #3

– Westfalia WSD

- 18

• Column #4

– Westfalia WSD

- 18

• Drill Floor

– Facet International MAS 34

- 31 1 ) Helideck Drains

The heli deck has a de dicated drainage system around its perimeter to drain heli

- fuel from a helicopter

incident. The fuel can be diverted to the designated heli

- fuel recovery tank which is located under the

Helideck structure.

Operating configurations are as follows:

 The ov erboard piping valves and hydrocarbons take on valves are closed and locked. To unlock overboard or take on valves a permit has to be filled out.

 The oily water collection tank overflow valve is closed.

 The drill floor drains are lined

- up to the drill flo or skimmer tank. The Skimmer tanks have a high alarm which sounds by means of an air horn. Before tanks are pumped out a sheen test is performed. Water is pump out the skimmer tanks down the shunt line. Oil containment side is pumped out into 550 gal tote tanks.

 The subsurface blowout preventer ( BOP ) test area drains are normally lined

- up to drain overboard.

 The oily water sep arator continuously circulates the oily water collection tank. Waste oil is discharged into the waste oil tank and oily water is re

- circulated back into the oily water collection tank. Clean water is pumped overboard, which is controlled and monitored by the oil content detector, set at 15

ppm.
 The solids control system is capable of being isolated for cuttings collection.

 The bilg e system is normally pumped directly overboard after a sheen test has been performed.

 The engine dirty oil sump can be drained down in Port column oily water sep arator which discharges water overboard from the water side and oil being pumped out into a 55 0 gal tote tank oil containment side. There is a high audible alarm on the ballast control panel.

D. Storage Tanks

- Noble Globetrotter

Type of Storage Tank Type of Tank Number of Total Fluid Facility Capacity

(bbls) Tanks Capacity (bbls) Gravity (API)

Fuel oil MODU 2

, 652 1 2

, 652 No. 2 diesel

Fuel oil MODU 1,743 1 1

, 743 No. 2 diesel

Fuel oil MODU 5

, 767 1 5

, 767 No. 2 diesel

Fuel oil MODU 4

, 399 1 4

, 399 No. 2 diesel

Fuel oil MODU 2

, 652 1 2

, 652 No. 2 diesel

Fuel oil MODU 3

, 250 1 3

, 250 No. 2 diesel

Fuel oil MODU 4

, 399 1 4

, 399 No. 2 diesel

Fuel oil MODU 2

, 618 1 2

, 618 No. 2 diesel

Fuel oil MODU 115 4 460 No. 2 diesel

Fuel oil MODU 129 4 516 No. 2 diesel

E. Pollution Prevention Measures

Pursuant to NTL 2008

- G04 the proposed operations covered by this EP do not require Shell to specifically address the discharges of oils and greases from the Rig during rainfall or routine operations. Nevertheless, Shell has provided this information as part of its response to 1(c ) above.

F. Additional Measures

 Health, safety, and environment (HSE) are the primary topics in pre

- tour and pre

- job safety meetings. The discussion around no harm to people or environment is a key mindset. All personnel are reminded daily to inspec t work areas for safety issues as well as potential pollution issues.

 All tools that come to and from the rig have their pollution pans inspected and cleaned, and plug installation confirmed prior to leaving the dock and prior to loading on the boat.

 Preve ntive maintenance of rig equipment includes visual inspection of hydraulic lines and reservoirs

on a routine scheduled basis. All pollution pans on rig are inspected daily.

 Containment dikes are installed around all oil containment, drum storage areas, fue l vents, and fuel storage tanks.

 All used oil and fuel is collected and sent to shore for recycling.

 Direct overboard drains on the rig are checked regularly to verify drain plugs are installed.

 All trash containers are checked and emptied daily, and trash containers are kept covered. Trash is collected in a compactor and shipped to shore for disposal.

 The rig is involved in a recycling program for cardboard, plastic, paper, glass, and aluminum.

 Fuel hoses are changed on annual basis.

 Spill prevention fitt ings are installed on all liquid take

- on hoses.

 Shell has obtained International Organization for Standardization (ISO) 14001 certification.

 Shell will use low

- sulfur fuel to reduce air pollutant impacts.Attachment 1 A

- B athymetry and Surface LocationsAttachment 1 B

Bottom Hole Locations

PROPRIETARY DATAAttachment 1 C

U. S. Department of the Interior OMB Control Number: 1010

- 0 151 Minerals Management Service OMB Approval Expires: December 31, 20 11 OCS PLAN INFORMATION FORM



### General Information

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

Company Name: Shell Offshore Inc. MMS Operator Number: 0689

Address: P. O. Box 61933 Contact Person: Tracy Albert

New Orleans, LA 70161

- 1933 Phone Number: 504.728.4652

E

- Mail Address: tracy.albert@shell.com

Lease(s): OCS

- G 31507 Area: MC Block(s): 525 Project Name (If Applicable): Rydberg Deep

Objective(s): X Oil Gas Sulphur Salt Onshore Base: Fouchon & Amelia Distance to Closest Land (Miles): 79



### Description of Proposed Activities (Mark all that apply)

X Exploration drilling Development drilling

Well completion Installation of production platform

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

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

Installation of subsea wellheads and/or manifolds Commence production

Installation of lease term pipelines Other (Specify and describe)

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

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

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

Do you propose any activities that may disturb an MMS

- designated high

- probability archaeological area? X Yes No

Have all of the surface locations of your proposed activities been previously reviewed and approved by

MMS? Yes X No



### Tentative Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Drill well A 0 5 /01/12 0 9 / 2 6 /12 14 8

Drill well B 0 5 / 0 1 /1 3 0 9 /0 6 /1 3 1 28

Drill well C 05 /0 1 /1 4 0 9 / 06 /1 4 1 28

Drill well D 0 5 / 01 /1 5 0 9 / 06 /1 5 1 28

Drill well E 0 5 / 01 /1 6 09 / 06 /1 6 1 28



### Description of Drilling Rig Description of Production Platform

Jackup X Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Compliant tower

Semisubmersible Submersible Fixed platform Guyed tower

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

Drilling Rig Name (If Known): Noble Globetrotter or similar Spar Other (Attach Description)



### Description of Lease Term Pipelines

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


### N/A

MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)

Attachment 1DOCS PLAN INFORMATION FORM (CONTINUED) Include one copy of this page for each proposed well/structure



### Proposed Well/Structure Location

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

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

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline Departures (in feet) N/S Departure: 1,882 ' F S L

E/W Departure: 1,206 ' F W L

Lambert X

- Y
coordinates X: 1, 331,766

Y: 10, 329,562

Latitude/ Longitude Latitude

28.46084 723 Longitude

- 87.96089 538 TVD (Feet): MD (Feet): Water Depth (Feet): 7,476‘

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

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or Development Operations Coordination Document submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of

Informatio n Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary . The public reporting burden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including the time for reviewing instructio ns, gathering and maintaining data, and completing and reviewing the form. Direct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240

. MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)Attachment 1E

OCS PLAN INFORMATION FORM (CONTINUED) Include one copy of this page for each proposed well/structure



### Proposed Well/Structure Location

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

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

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline Departures (in feet) N/S Departure : 2,112 ' FS L

E/W Departure: 7,470 ' F W L

Lambert X

- Y
coordinates X: 1, 338,030

Y: 10, 329,79 2

Latitude/ Longitude Latitude

28.4616 1632 Longitude

- 87.9 4140200 TVD (Feet): MD (Feet ): Water Depth (Feet): 7, 566 ‘

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

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or Development Operations Coordination Document submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently v alid Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate tha t burden to average 580 hours per response, including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct comments regarding the burden estimate or any other aspect of this form to the Informa tion Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240

. MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)Attachment 1F

OCS PLAN INFORMATION FORM (CONTINUED) Include one copy of this page for each proposed well/structure



### Proposed Well/Structure Location

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

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

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline Departures (in feet) N/S Departure: 1998 ' F S L

E/W Departure: 3410 ' F W L

Lambert X

- Y
coordinates X: 1, 333,970

Y: 10, 329,678

Latitude/ Longitude Latitude

28.46121 464 Longitude

- 87.95403 751 TVD (Feet): MD (Feet): Water Depth (Feet): 7,50 5 ‘

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

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or Development Operations Coordination Document submitted for MMS approval. We use the information to

faci litate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordin ation Documents. We estimate that burden to average 580 hours per response, including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct comments regarding the burden estimate or any other a spect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240

. MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)Attachment 1G

OCS PLAN INFORMATION FORM (CONTINUED) Include one copy of this page for each proposed well/structure



### Proposed Well/Structure Location

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

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

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline Departures (in feet) N/S Departure: 4202 ' F S L

E/W Departure: 5614 ' F W L

Lambert X

- Y
coordinates X: 1, 336,174

Y: 10, 331,882

Latitude/ Longitude Latitude

28.46732 2594 Longitude

- 87.94723 080 TVD (Feet): MD (Feet): Water Depth (Feet): 7,525‘

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

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or Development Operations Coordination Document submitted for MMS approval. We u se the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for preparing Exploration Plans and Deve lopment Operations Coordination Documents. We estimate that burden to average 580 hours per response, including the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct comments regarding the burd en estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington, DC 20240

. MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)Attachment 1H

OCS PLAN INFORMATION FORM (CONTINUED) Include one copy of this page for each proposed well/structure



### Proposed Well/Structure Location

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

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

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 31507

Area Name Mississippi Canyon

Block No. 525

Blockline Departures (in feet) N/S Departure: 4782 ' F S L

E/W Departure: 858 ‘ F W L

Lambert X

- Y
coordinates X: 1, 331,418

Y: 10, 332,462

Latitude/ Longitude Latitude

28.46881 763 Longitude

- 87.96205 091 TVD (Feet): MD (Feet): Water Depth (Feet): 7,466 ‘

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

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant‘s Exploration Plan or Development Operations Coordination Document submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect proprietary data according to the Freedom of

Information Act and 30 CFR 250.196 . An agency may not conduct or sponsor, and a person is not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Control Number. The use of this form is voluntary. The public reporting b urden for this form is included in the burden for preparing Exploration Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, including the time for reviewing instructions, gathering and

mainta ining data, and completing and reviewing the form. Direct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 4230, Minerals Management Service, 1849 C Street, N.W., Washington , DC 20240

. MMS FORM MMS

- 137 (December 2008

- Supersedes all previous editions of form MMS

- 137 which may not be used.)SECTION 2 : GENERAL INFORMATION

A. Application and Permits

There are no individual or site

- specific permits other than general NPDES Permit and rig move notification that

need to be obtained.

B. Drilling Fluids

See Section 7, Table 7A for a list of drilling fluids to be used.

C. Production

Information regarding production is not included in this EP as such information is only necessary in the case

of DOCDs.

D. Oil Characteristics

Information regarding Oil Characteristics is not included in this EP as such information is only necessary in the

case of DOCDs.

E. New Or Unusual Technology

Shell is not proposing to use new or unusual technology as defined in 30 CFR 250.200 to carry out the proposed

activities in this EP

.

F. Bonding

The bond requirement fo r the activities proposed in this EP are satisfied by an area

- wide bond furnished and

maintained according to 30 CFR Part 256 , S ubpart I

- Bonding ; NTL No. 2000

- G16

, ― Guideline for General Lease Surety Bonds‖ and National NTL No. 200 8

- N0 7 , ―Supplemental Bond Proc ed ures.‖

G. Oil Spill Financial Responsibility (OSFR)

Shell Offshore Inc

. (SOI), BOEM Operator Number 0689 , has demonstrated oil spill financial responsibility for

the wells proposed in the EP according to 30 CFR P art s 250 and 253 , and NTL No. 2008

- N0 5 , ―Guidelines for Oil Spill Financial Responsibility for Covered Facilities.‖

H. Deepwater well control statement

Shell Offshore Inc

. , BOEM Operator Number 0689 , has the financial capability to drill a relief well and conduct other emergency well control operations.

I. Suspension of Production

Information regarding Suspension of Production is not included in this EP as such information is only necessary in the case of DOCDs.J. Blowout scenario

Summary

This Section 2j was prepared by Shell Offshore Inc. (Shell) pursuant to the guidance provided in the Bureau of Ocean Energy Management, Regulation and Enforcement‘s ( BOEM ) Notice to Lessees (NTL) No. 2010

- N06 with respect to blowout and worst case discharge scenario descriptions

.

Shell focuses on an integrated, three

- pronged approach to a blowout, including prevention, intervention /containment, and recovery. Shell believes that the best way to manage blowouts is to prevent them from happening. Significant effort goes into the design and execution of wells and into building and maintaining staff competence with the goal of safe and environmentally sound well construction. Shell continues to invest independently in Research an d Development (R&D) to improve safety and reliability of our well systems. Shell intends to comply with all applicable laws, regulations, rules and Notice to Lessees.

Shell is investing in R&D to improve containment systems. As outlined in Shell‘s Oil Spi ll Response Plan (OSRP), and detailed in EP Section 9a (ii), Shell has contracts with Oil Spill Removal Organizations (ORSOs) to provide the resources necessary to respond to this Worst Case Discharge (WCD) scenario.

The Worst Case Discharge (WCD) blowout scenario for Rydberg Deep is calculated for the MC

- 525 C location

of the target Sand and based on the guidelines outlined in NTL No. 2010

- N06 along with subsequent Frequently Asked Questions (FAQ) . Shell is submitting MC

- 525 C well location as the worst

- c ase scenario to

the BOEM for inclusion in our Regional OSRP. In the unlikely event of a spill, Shell‘s Regional OSRP (August 2011) is designed to contain and respond to a spill that meets or exceeds this WCD. The WCD does not take into account potential fl ow mitigating factors such as well bridging, obstructions in wellbore, reservoir barriers, or early intervention. A summary of the WCD rate and spill volume for the total duration to drill a

relief well is contained in Table 1 below.

Uncontrolled blowout rate (first 30

- days average daily rate) (Note: this number includes max daily rate of 271 ,000 bbl/d on first day) 233 ,000 bopd Duration of flow (days) based on relief well 157 days

Total volume of spill (bbls) for 157 days 28.14 MMBO

Table 1 Worst Case Discharge Summary

The Rydberg Deep prospect is located approximately 79 miles east

- southeast of the nearest shoreline in the Gulf of Mexico (GOM), in water depths between approximately 7,400‘ and 7,600‘ across the prospect. The structural component o f the target is defined by a 3

- way against faults and salt, with the top of the objective

near

- 2 4

, 858 ft subsea (SS) at the well C location . The only objective horizon with predicted flow potential is

the target reservoir

.

1) Purpose

Pursuant to 30 CFR 250.213(g), 250.219, 250.250 , and NTL No. 2010

- N06 , this document provides a blowout scenario description, further information regarding any potential oil spill, the assumptions and calculations used to determine the WCD and the measures taken to 1) enhanc e the ability to prevent a blowout and 2) respond and manage a blowout scenario if it were to occur. These calculations are based on best technical estimates of subsurface parameters that are derived from regional target formation offset well s data and

sei smic data. These parameters are better than or consistent with the estimates used by Shell to justify the investment. Therefore, these assumed parameters were used to calculate the WCD. They do not reflect probabilistic estimates.

2) Background

This att achment has been developed to document the additional information requirements for Exploration Plans as requested by NTL No. 2010

- N06 in response to the explosion and sinking of the Mobile Offshore Drilling Unit (MODU) Deepwater Horizon.3) Information R equirements

a) Blowout scenario

All five locations in the proposed Rydberg Deep EP were assessed for WCD. The MC 525 well from the proposed C location near the crest of the trap represented the highest flow potential. The C well

will be drilled to the target reservoir as outlined in the Geological and Geophysical Information Section of the Initial EP using a subsea wellhead system, conductor, surface and intermediate casing program, and using a MODU rig with a marine riser and subsea blowout preventer (BOP). A hydrocarbon influx and a well control event are modeled to occur from the target reservoir. The simulated blowout modeled results in unrestricted flow from the well at the seafloor, which represents the WCD (no restrictions in wellbore, failure/lo ss of the subsea BOP, and a blowout to the seabed).

b) Estimated flow rate of the potential blowout

Category EP

Type of Activity Drilling

Facility Location (area/block) MC

- 525

Facility Designation Noble Globetrotter

Distance to Nearest Shoreline (miles) 79 Statute miles
Uncontrolled blowout rate (first 30

- days average daily rate) (Note: this number includes max daily rate of 271 ,000 bbl/d on first day) 233 ,000 bopd

Table 2 Estimated Flow Rates of a Potential Blowout

c) Total volume and maximum duration of the potential blowout

Duration of flow (days) 157 days total duration to drill relief well (14 rig mob, 4 transit, 111 spud to top target , 28 ranging).

Total volume of spill (bbls) 28.14 MMBO based on 157 days flowing. Note: From CMG dynamic reservoir model Note: ( 233 ,000 bopd * 30 days) + ( 166

, 5 00 bopd * 127 days) = ~ 28

. 1 4

MMBO over 157 days.
Table 3 Estimated Duration and Volume of a Potential Blowout

There is usually a decline in the discharge rate as time proceeds, which is illustrated by the

differences between the first 24

- hour volume and 30

- day average rate. At very short times, e.g. during the first 24 hours, the pressure profile in the reservoir changes from the moment when a well first starts flowing (transient pressure profile) to a pseudo

- steady state pressure profile with time, and as a result the rate declines. At somewhat longer time scales, effects such as reservoir voidage and the impact o f boundaries can cause the rate to drop continuously with production. Simulation

models can include these effects and form the basis of the NTL No. 2010

- N06 calculations for 24

- hour and 30

- day rates as well as maximum duration volumes.

d) Assumptions and calculations used in determining the worst case discharge (Proprietary)

e) Potential for the well to bridge over

Mechanical failure/collapse of the borehole in a blowout scenario is influenced by several factors including in

- situ stress, rock strength, and fluid velocities at the sand face. Given the substantial fluid velocities inherent in the WCD, and the scenario as defined where the formation is not supported by a cased and cemented wellbore, it is possible that the borehole may fail/collap se/bridge over within the span of a few days, significantly reducing the outflow rates. However, th e WCD scenario contained in this report does not include any bridging.f) Likelihood for intervention to stop the blowout.

Safety of operations is Shell‘s top priority. Maintaining well control at all times to prevent a blowout is the key focus of our operations. This is derived from robust standards, well design, prudent operations, competency of personnel, and strong HSE foc us. Collectively, these constitute a robust system making blowouts extremely rare events.

Intervention Devices: Notwithstanding these facts, the main scenario for recovery from a blowout

event is via intervention with the BOP attached to the well. There are built in redundancies in the BOP system to allow activation of selected components with the intent to seal off the well bore. As a minimum, the Shell contracted rig fleet in the GOM will have redundancies meeting NTL No. 2010

- N05 (to the extent applica ble) and the Drilling Safety Rule with respect to Remotely Operated Vehicle (ROV) hot stab capabilities, a deadman system, and an autoshear system.

Containment: The experience of gaining control over the Macondo well has resulted in a better understanding of the necessary equipment and systems for well containment. As a result, industry and government are better equipped and prepared today to contain an oil well blowout in deepwater (See page 17 of the Decision Memorandum dated October 1, 2010). Shell is f urther analyzing these advances and incorporating them into its comprehensive approach to help prevent and, if needed, control another deepwater control incident.

Should the interventions at the well not be possible, specialized equipment will be used t o connect to a riser stub, damaged connector, casing stub, or to the sea floor and allow the well to be shut

- in to contain the blowout. The subsea containment assembly and other specialized connection devices will

be available from the Marine Well Containm ent Company (MWCC). If full shut

- in, following capping is not possible because of well integrity issues, the well can be flowed with back

- pressure maintained via the MWCC specialized well flow equipment. Shell is a founding member of the Marine Well

Contai nment Company which has the containment equipment and contracts for access to response capability. The response capability will incorporate lessons learned and technology advances as they apply to containment. The MWCC website can be accessed for a full de scription of the systems and components. The MWCC owns, maintains, and will deploy both existing equipment and equipment being constructed for well intervention and containment. The newly constructed system has been designed to be flexible and adaptable, and be responsive to a wide range of potential scenarios, deepwater depths up to 10,000 feet, weather conditions, and flow rates. The system components will be fully tested to ensure functionality and will be maintained in a state of continuous operational readiness. In the event of a future incident, mobilization to the field will start within days and the system will be fully operational within weeks. The new containment system will further enhance Shell‘s Regional OSRP. A detailed capping proposal will be provided as part of the Application Permit to Drill ( APD ) submission.

Shell is investing in Research and Development activities on its own to identify additional containment components and equipment that will potentially increase the range of applicati ons and effectiveness for equipment similar to that of MWCC, and systems that can be deployed more effectively in the water column that resemble ―tents or capture domes‖, and thus enhance well shut

- in capability.

g) Availability of a rig to drill a relie f well and rig package constraints

Blowout intervention can be conducted from an ROV equipped vessel, the existing drilling rig or from another drilling rig. Shell has an active portfolio of well operations in the GOM which will be supported by a total of four to six MODU rigs in 2011

– 2015 timeframe. The dynamically positioned rigs under contract, the Noble Danny Adkins, Noble Globetrotter , and the Noble Bully 1, will be the preferred rigs for blowout intervention work. However, moored rigs can also be u sed in some scenarios. Additionally, in the event of a blowout, there is the distinct possibility that other non

contracted rigs in the GOM could be utilized whether for increased expediency or better suitability. All

efforts will be made at the time to se cure the appropriate rig. Shell‘s current contracted rigs capable of operating at Rydberg Deep water depths and reservoir depths are in the following table:Rig Name Rig Type Noble Danny Adkins dynamically positioned semi Noble Bully 1 dynamically positioned drill ship Deepwater Nautilus Moored semi Noble Jim Thompson Moored semi

Noble Globetrotter * dynamically positioned drill ship

Table 4 Shell Contracted Rigs Capable at Rydberg Deep.

Above are current as of December 2011. Future modifications may change the rig’s capability.

Rig capabilities need to be assessed on a work scope specific basis.

* Noble Globetrotter estimated arrival March 201 2

h) Time taken to contract a rig, move it onsite, and drill a relief well

Relief well operations will immediately take priority and displace any activity from Shell‘s contracted rig fleet. Table 4 lists the Shell contracted rigs capable of operating at Rydberg Deep. It is expected to take an average of 14 days to safely secure the well that the rig is working on up to the point the rig departs location, and an additional 4 days transit to mobilize to the relief well site depending on distance to the site. The relief well will take approximately 111 days to drill down to the last casing string above the blowout zone, approximately 28 days for precision ranging activity to intersect the blowout well bore. Total time to drill a relief well would be ~157 days for the Rydberg Deep relief

well.

If a moored rig is chosen to conduct th e relief well operations, anchor handlers would be prioritized to prepare mooring on the relief well site while the rig is being mobilized. This mooring activity is not expected to delay initiation of relief well drilling operations. Shell has three deepwa ter anchor handlers, the Laney, Dino, and Ross Chouest, on long term contract to support its moored rigs.

It is not possible to drill relief wells from any existing platforms. Relief well locations well be planned 1,500

- 3,000 ft from the existing well lo cation

i) Measures proposed to enhance ability to prevent blowout and to reduce likelihood of a

blowout.

Shell believes that the best way to manage blowouts is to prevent them from happening. Detailed below are the measures employed by Shell with the goal of no harm to people or the environment. The Macondo incident has highlighted the importance of these pra ctices. The lessons learned from the investigation are, and will continue to be, incorporated into our operations. Measures proposed to enhance the ability to prevent a blowout and to reduce the likelihood of a blowout include the following:

Standards: Sh ell‘s well design and operations adhere to internal corporate standards, the Code of Federal Regulations, and industry standards. A robust management of change process is in place to

handle un

- defined or exception situations. Ingrained in the Shell standar ds for well control is the philosophy of multiple barriers in the well design and operations on the well.

Risk Management: Shell believes that prevention of major incidents is best managed through a systematic identification and mitigation process (Safet y Case). All Shell contracted rigs in the GOM have been operating with a Safety Case and will continue to do so. A Safety Case requires both the owner and contractors to systematically identify the risks in drilling operations and align plans to mitigate those risks; an alignment which is critical before drilling begins.

Well Design Workflow: The Well Delivery Process (WDP) is a rigorous internal assurance process with defined decision gates. The WDP leverages functional experts (internal and external) t o examine the well design at the conceptual and detailed design stages for robustness before making a recommendation to the management review board. Shell‘s involvement in global deepwater drilling, starting in the GOM in the mid

- 1980‘s, provides a signifi cant depth and breadth of internal drillingand operational expertise. Third party vendors and rig contractors are involved in all stages of the

planning, providing their specific expertise. A Drill the Well On Paper (DWOP) exercise is conducted with rig p ersonnel and vendors involved in execution of the well. This forum communicates the well plan, and solicits input as to the safety of the plan and procedures proposed.

Well and rig equipment qualification, certification, and quality assurance: All rigs wi ll meet all applicable rules, regulations, and Notice to Lessees. Shell works closely with rig contractors to ensure proper upkeep of all rig equipment, which meets or exceeds the strictest of Shell, industry, or regulatory requirements. Well tangibles are governed by our internal quality assurance/control standards and industry standards.

MWD/LWD/PWD Tools: Shell intends to use these tools at Rydberg Deep. The MWD/LWD/PWD tools are run on the drill string so that data on subsurface zones can be collected as the well advances in real time instead of waiting until the drill string is pulled to run wireline logs. Data from the tools are monitored and interpreted real time against prognosis to provide early warning of abnormal pressures to allow measures to be taken to progress the well safely.

Mud Logger: Mud logging personnel continually monitor returning drilling fluids for indications of hydrocarbons, utilizing both a hot wire and a gas chromatograph. An abrupt increase in gas or oil

carried in the return ing fluid can be an indication of an impending kick. The mud logger also monitors drill cuttings returned to the surface in the drilling fluid for changes in lithology that can be an indicator that the well has penetrated or is about to penetrate a hydrocarbon

- bearing interval. Mud logging instruments also monitor penetration rate to provide an early indication of drilling breaks that

show the bit penetrating a zone that could contain hydrocarbons. The mud logging personnel are in

close communication with both the drilling foreman and Shell representative to report any observed anomalies so appropriate action can be taken.

Remote Monitoring: The Real Time Operating Center has been used by Shell to complement and support traditional rig

- site monitorin g since 2003. Well site operations are lived virtually by onshore teams consisting of geoscientists, petrophysicists, well engineers, and 24/7 monitoring specialists. The same real time well control indicators monitored by the rig personnel are watched by the monitoring specialist for an added layer of redundancy.

Competency and Behavior: A structured training program for Well Engineers and Forem e n is practiced, which includes internal professional examinations to verify competency. Other industry

trainin g in well control, such as by International Association of Drilling Contractors (IADC) and International Well Control Forum (IWCF) are also mandated. Progressions have elements of competency and Shell continues to have comprehensive internal training progr ams. The best systems and processes can be defeated by lack of knowledge and/or improper values. We believe that a combination of HSE tools (e.g. stop work, pre

- job analysis, behavior based safety, DWOPs, and audits), management HSE involvement and enforce ment (e.g. compliance to life saving rules) have created a strong safety culture in our operations.

j) Measures to conduct effective and early intervention in the event of a blowout.

The response to a blowout is contained in our Well Control Contingency Plan (WCCP) which is a specific requirement of our internal well control standards. The WCCP in turn is part of the wider emergency response framework within Shell that addresses the overall organization response to an emergency situation. Resources are d edicated to these systems and drills are run frequently to test preparedness (security, medical, oil spill, and hurricane). This same framework is activated and tested during hurricane evacuations, thereby maintaining a fresh and responsive team.

The WCCP specifically addresses implementing actions at the emergency site that will ensure personnel safety, organizing personnel and their roles in the response, defining information requirements, establishing protocols to mobilize specialists and pre

- selecting sources, and developing mobilization plans for personnel, material and services for well control procedures. The plan references individual activity checklists, a roster of equipment and services, initial information gathering forms, a generic description of relief well drilling, strategy and guidelines, intervention techniques and equipment, site safety management, exclusion zones, and re

- boarding.k) Arrangements for drilling a relief well

The size of the Shell contracted rig fleet in the GOM from 2011

- 2015 ensures that there is adequate well equipment (e.g. casing and wellhead) available for relief wells. Rigs and personnel will also be readily available within Shell, diverted from their ac tive roles elsewhere. Resources from other operators can also be leveraged should the need arise. Generally, relief well plans will mirror the blowout well, incorporating any learning on well design based on root cause analysis of the blowout. A generic re lief well description is outlined in the WCCP.

l) Assumptions and calculations used in approved or proposed OSRP

MC 807 Subsea Well A was submitted as subsea WCD in our OSRP update of August 1, 2011 and was

covered for 2010

- N06 in Plan S

- 7499 (pending BOEM approval). Shell has designed a response program (Regional OSRP August 2011) based upon a regional capability of responding to a range of spill volumes, from small operational spills up to and including the WCD from a well blowout. Shell‘s program is developed to fully satisfy federal oil spill planning regulations. The Regional OSRP presents specific information on the response program that includes a description of personnel and equipment mobilization, the incident management team organization, and the strategies and tactics used to implement effective and sustained spill containment and recovery operations.

K. Chemical Products

Information regarding chemical products is not included in this EP as such information is not required by

BOEM GOMR.SECTION 3 : GEOLOGICAL AND GEOPHYSICAL INFORMATION

A. Geological description

Proprietary data.

B. Structure Contour Map(s)

Proprietary data.

C. Interpreted 2D and/or 3D Seismic line(s)

Proprietary data.

D. Geological Structure Cross

- section(s)

Proprietary data.

E. Shallow Hazards Report

The following reports were used for our analysis:

AUV Hazard study prepared by C&C Technologies, dated February 2009, Project # 083926

- 084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, and 613, for Mississippi Canyon 525, Pro posed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400

- 2040 for DeSoto Canyon Blocks 485 and 529 and Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and Murphy E&P‘s previously submi tted shallow hazards report No. 2400

- 2070, prepared by Fugro Geoservices,

for OCS

- G 19960, Mississippi Canyon 524 dated March 14, 2001 are also used for this EP.

Shallow Hazards Assessment

History

Shell is submitting an Initial Exploration Plan (EP) and AUV Hazard study prepared by C&C Te chnologies, dated February 2009 ( Project # 083926

- 084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, and 613 ) , for Mississippi Canyon 525, Proposed Locations A, B, C, D and E

.

Previously filed Geohazards Assessment No. 2400

- 2040 for DeSoto Canyon Blocks 485 and 529 and Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and Murphy E&P‘s previously submitted shallow hazards report No. 2400

- 2070, prepared by Fugro Geoservices,

for OCS

- G 19960, Mississippi Canyon 524 dated March 14, 2001 are also used for this EP.

Proposed Location A, Mississippi Canyon 525: Datum: D_North_American_1927 Projection: Transverse_Mercator NAD_1927_BLM_Zone_ 16N

X = 1,331,766 ft; Latitude = 28.460847229°N; Inline= 13

, 004; 1

, 206‘ FWL

Y = 10 ,329,562 ft; Longitude =

- 87.960895381°W; Crossline =10

, 166; 1

, 882‘ FSLMississippi Canyon 525, Proposed Location A is located in a water depth of approximately 7

, 476 feet. There

is no evidence of seafloor or near

- surface faulting within 2

, 000 feet of Proposed Location A. Proposed Location A will be positioned 15

, 598 feet northeast of Shell‘s previously drilled MC 568 #1 wellsit e.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location A consists of Unit 1 approximately 329 feet of normal marine drape overlying Unit 2 which is 123 feet of interbedded thin sands, silts and clay

prone distal slope fan deposits. Unit 3 is identified 452 to 1

, 910 feet below the mud line, consisting of approximately 1

, 458 feet of muds and fine

- grained mass transport deposits. Unit 4 is identified 1

, 910 to

2

, 530 feet below the mud line, consisting of 620 feet of muddy mass

- transport complex deposits. Unit 5 is

identified 2

, 530 to 4

, 004 feet below the mud line, consisting of 1

, 474 feet of sand

- prone, channel/overbank deposits interbedded with fine

- grained mass transport deposits. Unit 6 is identified 4

, 004 to 7

, 320 feet below

the mu d line, consisting of 810 feet of fine

- grained mass transport deposits with possible interbedded

discontinuous sands over sand

- prone channel/overbank deposits interbedded with fine

- grained mass transport deposits, over a 2506 foot

- thick section consisting of mostly muds interbedded with sand over a

more mud

- prone section. Unit 7 is identified 7

, 320 to 11

, 551 feet below the mud line. This 4

, 231 foot

- thick unit consists of a potential sand

- prone interval near the top, with a more mud

- dominated structure in the lower part of the interval.

An amplitude anomaly is identified approximately 125 feet from Proposed Location A within Unit 6, approximately 4

, 425 feet below the mud line. There are no other amplitude anomalies or bright

- spots
identified in the vicini ty of Mississippi Canyon 525, Proposed Location A. Proposed Location A is not expected to penetrate any amplitude anomalies.

Moderately low potential for shallow gas is identified 4

, 004 to 7

, 320 feet below the mud line. Low potential for shallow gas is identified from the seafloor to 4

, 004 feet below the mud line, and 7

, 320 to 11

, 551 feet

below the mud line.

The potential for shallow water flow is identified as low from the seafloor to 11

, 551 feet below the mud line for Mississippi Canyon, Proposed Lo cation A.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Lo cation A appears suitable for the planned activity.

Proposed Location B, Mississippi Canyon 525: Datum: D_North_American_1927 Projection: Transverse_Mercator NAD_1927_BLM_Zone_16N

X = 1,338,030 ft; Latitude = 28.461616320°N; Inline= 13

, 116; 7

, 470‘ FWL Y = 10,329,792 ft; Longitude =

- 87.941402002°W; Crossline =10

, 062; 2

, 112‘ FSL

Mississippi Canyon 525, Proposed Location B is located in a water depth of approximately 7

, 566 feet. There

is n o evidence of seafloor or near

- surface faulting within 2

, 000 feet of Proposed Location B. Proposed Location B will be positioned 20

, 468 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 52 5, Proposed Location B consists of Unit 1 approximately 257 feet of normal marine drape overlying Unit 2, which is 101 feet of interbedded thin sands, silts and clay

prone distal slope fan deposits. Unit 3 is identified 358 to 1

, 870 feet below the mud lin e, consisting of approximately 1

, 512 feet of muds and fine

- grained mass transport deposits. Unit 4 is identified 1

, 870 to

2

, 425 feet below the mud line, consisting of 555 feet of fine

- grained mass

- transport complex deposits. Unit 5

is identified 2

, 425 to 3

, 858 feet below the mud line, consisting of 1

, 433 feet of sand

- prone, channel/overbank deposits interbedded with fine

- grained mass transport deposits. Unit 6 is identified 3

, 858 to 7

, 078 feet below the mud line, consisting of 956 feet of fine

- grained ma ss transport deposits with possible interbedded

discontinuous sands over sand

- prone channel/overbank deposits interbedded with fine

- grained mass transport deposits and a 2

, 264 foot

- thick unit consisting of mostly muds interbedded with sand over a more

mud

- prone section. Unit 7 is identified 7

, 078 to 10

, 885 feet below the mud line. This 3

, 807 foot

- thick unit consists of a potential sand

- prone interval near the top, with a more mud

- dominated structure in the lower part of the interval.A moderate amplitude anomaly is identified approximately 300‘ from Proposed Location B within Unit 6,

approximately 4

, 234 feet below the mud line. There are no other amplitude anomalies or bright

- spots identified in the vicinity of Mississippi Canyon 525, Proposed Location B . Proposed Location B is not expected to penetrate any amplitude anomalies.

Low potential for shallow gas is identified the seafloor 10

, 885 feet below the mud line.

The potential for shallow water flow is identified as low from the seafloor to 10

, 885 feet below the mud line for Mississippi Canyon, Proposed Location B.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous U nderwater Vehicle) survey, Mississippi Canyon 525, Proposed Location B appears suitable for the planned activity.

Proposed Location C, Mississippi Canyon 525: Datum: D_North_American_1927 Projection: Transverse_Mercator NAD_1927_BLM_Zone_16N

X = 1,333 ,970 ft; Latitude = 28.461214644°N; Inline= 13

, 044; 3

, 410‘ FWL Y = 10,329,678 ft; Longitude =

- 87.954037508°W; Crossline =10

, 130; 1

, 998‘ FSL

Mississippi Canyon 525, Proposed Location C is located in a water depth of approximately 7

, 505 feet. There

is no evidence of seafloor or sub

- surface faulting within 2000 feet of Proposed Location C. Proposed Location C will be positioned 17

, 232 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location C consists of Unit 1 approximately 300 feet of normal marine drape overlying Unit 2, which is 117 feet of interbedded thin sands, silts and clay

prone distal slope fan deposits. Unit 3 is identified 417 to 1

, 894 feet below the mud line, consisting of approximately 1

, 477 feet of muds and fine

- grained mass transport deposits. Unit 4 is identified 1

, 894 to

2

, 482 feet below the mud line, consisting of 588 feet of fine

- grained mass

- transpor t complex deposits. Unit 5

is identified 2

, 482 to 3

, 966 feet below the mud line, consisting of 1

, 484 feet of sand

- prone, channel/overbank deposits interbedded with fine

- grained mass transport deposits. Unit 6 is identified 3

, 966 to 7

, 215 feet below

the m ud line, consisting of 812 feet of fine

- grained mass transport deposits with possible interbedded

discontinuous sands over sand

- prone channel/overbank deposits interbedded with fine

- grained mass transport deposits, and a 2

, 437 foot

- thick section consisting of mostly muds interbedded with sand over a

more mud

- prone section. Unit 7 is identified 7

, 215 to 11

, 275 feet below the mud line. This 4

, 060 foot

- thick unit consists of a potential sand

- prone interval near the top, with a more mud

- dominated structure in the lower part of the interval.

A moderate amplitude anomaly is identified approximately 4

, 400 feet below the mud line in Unit 6. Another moderate amplitude anomaly is identified approximately 475 feet from Proposed Location C within Unit 5.approximatel y 3

, 200 feet below the mud line. There are no other amplitudes or bright

- spots identified in the vicinity of Mississippi Canyon 525, Proposed Location C. The casing program for Proposed Location C is designed for possible amplitude penetration.

Moderate ly low potential for shallow gas is identified 2

, 482 to 3

, 966 feet below the mud line. Low potential for shallow gas is identified from the seafloor to 2

, 482 feet below the mud line, and 3

, 966 to 11

, 275 feet

below the mud line.

The potential for shallo w water flow is identified as low from the seafloor to 11

, 275 feet below the mud line for Mississippi Canyon, Proposed Location C.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ES R‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Location C appears suitable for the planned activity.Proposed Location D, Mississippi Canyon 525:

Datum: D_North_American_1927 Projection: Transverse_Mercator NAD_1927_BLM_Zone_16N

X = 1,336,174 ft; Latitude = 28.467325943°N; Inline= 13

, 120; 5

, 614‘ FWL Y = 10,331,882 ft; Longitude =

- 87.947230796°W; Crossline =10

, 130; 4

, 202‘ FSL

Mississippi Canyon 525, Proposed Location D is located in a water depth of approximately 7

, 525 feet. There

is no evidence of seafloor or near

- surface faulting within 2

, 000 feet of Proposed Location D. Proposed Location D will be positioned 20

, 347 fe et northeast of Shell‘s previously drilled wellsite.

The stratigraphy at the site of Mississippi Canyon 525, Proposed Location D consists of Unit 1 approximately 271 feet of normal marine drape overlying Unit 2, which is 117 feet of interbedded thin sands , silts and clay

prone distal slope fan deposits. Unit 3 is identified 388 to 1

, 891 feet below the mud line, consisting of approximately 1

, 503 feet of muds and fine

- grained mass transport deposits. Unit 4 is identified 1

, 891 to

2

, 407 feet below the mud l ine, consisting of 516 feet of fine

- grained mass

- transport complex deposits. Unit 5

is identified 2

, 407 to 3

, 861 feet below the mud line, consisting of 1

, 454 feet of sand

- prone, channel/overbank deposits interbedded with fine

- grained mass transport deposi ts. Unit 6 is identified 3

, 861 to 7

, 141 feet below the mud line, consisting of 908 feet of fine

- grained mass transport deposits with possible interbedded

discontinuous sands over sand

- prone channel/overbank deposits interbedded with fine

- grained mass transport deposits and a 2

, 372 foot

- thick section consisting of mostly muds interbedded with sand over a

more mud

- prone section. Unit 7 is identified 7

, 141 to 11

, 038 feet below the mud line. This 3

, 897 foot

- thick unit consists of a potential sand

- prone i nterval near the top, with a more mud

- dominated structure in the lower part of the interval.

Proposed Location D may penetrate a moderately high amplitude anomaly in Unit 6, approximately 4

, 275 feet below the mud line. There are no other amplitudes or br ight

- spots identified in the vicinity of Mississippi Canyon 525, Proposed Location D. The casing program for Proposed Location D is designed for possible amplitude penetration.

Moderately high potential for shallow gas is identified 3

, 861 to 7

, 141 feet b elow the mud line, in Unit 6. Low potential for shallow gas is identified from the seafloor to 3861 feet below the mud line and 7

, 141 to 11

, 038

feet below the mud line.

The potential for shallow water flow is identified as low from the seafloor to 11

, 0 38 feet below the mud line for Mississippi Canyon, Proposed Location D.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Un derwater Vehicle) survey, Mississippi Canyon 525, Proposed Location D appears suitable for the planned activity.

Proposed Location E, Mississippi Canyon 525 Datum: D_North_American_1927 Projection: Transverse_Mercator NAD_1927_BLM_Zone_16N

X = 1,331,41 8 ft; Latitude = 28.468817633°N; Inline= 13

, 048; 858‘ FWL Y = 10,332,462 ft; Longitude =

- 87.962050905°W; Crossline =10

, 222; 4

, 782‘ FSL

Mississippi Canyon 525, Proposed Location E is located in a water depth of approximately 7

, 466 feet. There

is no evidence of seafloor or sub

- surface faulting within 2

, 000 feet of Proposed Location E. Proposed Location E will be positioned 17

, 653 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite.

Th e stratigraphy at the site of Mississippi Canyon 525, Proposed Location E consists of Unit 1 approximately 300 feet of normal marine drape overlying Unit 2, which is 126 feet of interbedded thin sands, silts and clay

prone distal slope fan deposits. Unit 3 is identified 426 to 1

, 884 feet below the mud line, consisting of approximately 1

, 458 feet of muds and fine

- grained mass transport deposits. Unit 4 is identified 1

, 884 to

2

, 496 feet below the mud line, consisting of 612 feet of fine

- grained mass

- transpo rt complex deposits. Unit 5

is identified 3

, 943 to 7

, 320 feet below the mud line, consisting of 1

, 447 feet of sand

- prone, channel/overbank deposits interbedded with fine

- grained mass transport deposits. Unit 6 is identified 3

, 943 to 7

, 320 feet below

the mud line, consisting of 872 feet of fine

- grained mass transport deposits with possible interbeddeddiscontinuous sands over sand

- prone channel/overbank deposits interbedded with fine

- grained mass

transport deposits, and a 2505 foot

- thick section consisting of mostly muds interbedded with sand over a

more mud

- prone section. Unit 7 is identified 7

, 320 to 11

, 540 feet below the mud line. This 4

, 220 foot

- thick unit consists of a potential sand

- prone interval near the top, with a more mud

- dominated structure in the lower part of the interval.

There are no amplitude anomalies identified in the vicinity of Proposed Location E. Proposed Location E is not expected to penetrate any amplitude anomalies.

Low potential for shallow gas is identified from the seafloor to 11

, 540 feet below the mud line for Mississippi Canyon, Proposed Location E.

The potential for shallow water flow is identified as low from the seafloor to 11

, 540 feet below the mud line.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Location E appears suitable for the planned activity.

Adam Chow Arlette. C. Nunez Geophysicist Shallow Hazard Coordinator

F. High

- Resolution Seismic Lines

Proprietary data.

G. Tophole Prognosis

Proprietary data. ( ESR map s can be found in Section 6 , Attachment 6A

. )

H. Stratigraphic Column with Time vs depth table

Proprietary data.

I

. Geochemical Information

This information is not required for Plans submitted in the GOM Region.

J. Future G&G Activities

This information is not required for Plans submitted in the GOM Region.SECTION 4: HYDROGEN SULFIDE (H 2 S) INFORMATION

A. Concentration

0

- 4 0 ppm

B. Classification

Based on 30 CFR 250. 490 (c), Shell requests that the Regional Supervisor, Field Operations, determine the zones in the proposed drilling operations in this plan to be classified as an area where the absence of H 2 S is unknown

.

Shell will submit to the appropriate BOEM GOMR district office an H 2 S Contingency Plan prepared according to 30 CFR 250.490(f) before conducting the proposed exploration activities.

C. Modeling Report

We do not anticipate to encounter or handle H 2 S at concentrations greater than 500 parts per million (ppm) and therefore have not included modeling for H 2 S.SECTION 5 : MINERAL RESOURCE CONSERVATION INFORMATION

Information regarding Mineral Resource Conservation is not included in this EP as such informa tion is only necessary in

the case of DOCDs.SECTION 6 : BIOLOGICAL, PHYSICAL, AND SOCIOECONOMIC INFORMATION

A. Chemosynthetic Communities Report

Biological Information

In accordance with NTL 2009

- G40, dated January 27, 2010, for water depths greater than 984 feet :

Mississippi Canyon 525, Proposed Locations A, B, C, D and E

 Features or areas that could support high

- density chemosynthetic communities are not within 2,000 feet of each proposed mud and cuttings discharg e location.

History

Shell is submitting an Initial Exploration Plan (EP), AUV Hazard study prepared by C&C Technologies, dated February 2009, Project # 083926

- 084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, a nd 613, for Mississippi Canyon 525, Proposed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400

- 2040 for DeSoto Canyon Blocks 485 and 529 and Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and Murphy E&P‘s previously submitted shallow hazards report No. 2400

- 2070, prepared by Fugro Geoservices,

for OCS

- G 19960, Mississippi Canyon 524 dated March 14, 2001 are also used for this EP.

Proposed Location A, Mississippi Canyon 525:

X = 1,331,766 1206‘ FWL Y = 10,329,562 1882‘ FSL

Mississippi Canyon 525, Proposed Location A is located in a water depth of approximately 7476 feet. There is

no evidence of seafloor or near

- surface faulting, slumping, amplitudes or fluid expulsion features within 2000‘ of Proposed Location A. Proposed Location A will not disturb any high

- density areas of chemosynthetic

communities.

Proposed Location A will be positioned 15598 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. Proposed Location A will not disturb any previously drilled wellsites.

Sonar Target #24 is located 2860 feet southeast of Proposed Location A. This target has been identified as modern debris. An avoidance zone of 100‘ surrounds this target. There are no other sonar targets identified within 3000‘ of Proposed Location A.

Currently, there are no flowlines in the vicinity of Mississippi Canyon 525, Proposed Location A.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D s eismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Location A appears suitable for the planned activity.

Proposed Location B, Mississippi Canyon 525 :

X = 1,338,030 7470‘ FWL Y = 10,329,792 2112‘ FSL

Mississippi Canyon 525, Proposed Location B is located in a water depth of approximately 7

, 566 feet. There

is no evidence of seafloor or near

- surface faulting, slumping, amplitude or fluid expulsion features within 2000‘ of Proposed Location B. Proposed Location B will not disturb any high

- density areas of chemosynthetic

communities.

Proposed Location B will be positioned 20

, 468 feet northeast of Shell‘s previously drilled MC568 #1 wellsi te. Proposed Location B will not interfere with any previously drilled wellsites.Sonar Target #20 is located 909 feet north of Proposed Location B. Sonar Target #19 is located 1891 feet

east of Proposed Location B. Sonar Target #19 is located 1891 fee t north of Proposed Location B. All of these targets are identified as modern debris. Avoidance zones of 100‘ surround each target. There are no other sonar targets identified within 3

, 000‘ of Proposed Location B.

Currently, there are no flowlines in t he vicinity of Mississippi Canyon 525, Proposed Location B.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Veh icle) survey, Mississippi Canyon 525, Proposed Location B appears suitable for the planned activity.

Proposed Location C, Mississippi Canyon 525:

X = 1,333,970 3410‘ FWL Y = 10,329,678 1998‘ FSL

Mississippi Canyon 525, Proposed Location C is located in a water depth of approximately 750 5 feet. There is

no evidence of seafloor or near

- surface faulting, slumping, amplitude or fluid expulsion features within 2000‘ of Proposed Location C. Proposed Location C will not disturb any high

- density areas of chemosynthetic

communities.

Proposed Location C will be positioned 17232 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. Proposed Location C will not interfere with any previously drilled wellsites.

There are no sonar targets identified within 3

, 000‘ of Proposed Location C.

Currently, there are no flowlines in the vicinity of Mississippi Canyon 525, Proposed Location C.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced

Surfa ce Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Location C appears suitable for the planned activity.

Proposed Location D, Mississippi Canyon 525:

X = 1,336,174 5

, 614‘ FWL Y = 10,331,882 4,202‘ FSL

Mississippi Canyon 525, Proposed Location D is located in a water depth of approximately 7

, 525 feet. There

is no evidence of seafloor or near

- surface faulting, slumping, amplitude or fluid expulsion features within

2

, 000‘ of Proposed Location D. Proposed Location D will not disturb any high

- density areas of chemosynthetic communities.

Proposed Location D will be positioned 20

, 347 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. Proposed Loca tion D will not interfere with any previously drilled wellsites.

Sonar Target #16 is located 983 feet north of Proposed Location D. Sonar Target #18 is located 1

, 382 feet east of Proposed Location D. Sonar Target #20 is located 2064 feet southeast of Pr oposed Location D. All of these targets are identified as modern debris. Avoidance zones of 100‘ surround each target. There are no other sonar targets identified within 3

, 000‘ of Proposed Location D.

Currently, there are no flowlines in the vicinity o f Mississippi Canyon 525, Proposed Location D.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced Surface Renderings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle)

survey, Mississippi Canyon 525, Proposed Location D appears suitable for the planned activity.Proposed Location E, Mississippi Canyon 525

X = 1,331,418 858‘ FWL Y = 10,332,462 4782‘ FSL

Mississippi Canyon 525, Proposed Location E is located in a water depth of approximately 7

, 466 feet. There

is no evidence of seafloor or near

- surface faulting, slumping, amplitude or fluid expulsion features within

2

, 000‘ of Proposed Location E. Proposed Location E will not disturb any high

- density areas of chemosynthetic

communities.

Proposed Location E will be positioned 17

, 653 feet northeast of Shell‘s previously drilled MC 568 #1 wellsite. Proposed Location E will not interfere with any previously drilled wellsites.

There are no sonar targets identifi ed within 3

, 000‘ of Proposed Location E.

Currently, there are no flowlines in the vicinity of Mississippi Canyon 525, Proposed Location E.

Based on a high

- resolution geophysical survey, consisting of frequency enhanced 3

- D seismic, Enhanced

Surface Rende rings (ESR‘s), ESR‘s with amplitudes applied, and AUV (Autonomous Underwater Vehicle) survey, Mississippi Canyon 525, Proposed Location E appears suitable for the planned activity.

Adam Chow Arlette. C. Nunez Geophysicist Shallow Hazard Coordin ator

B

- F

Pursuant to NTL No. 2008

- G04 the proposed operations covered by this EP do not involve operations impacting the following: Topographic features map, Topographic features statement (shunting), Live bottoms, (Pinnacle Trend) map, Live bottoms (low relief) map, or potentially sensitive biological features

map.

G. Remotely Operated Vehicle (ROV) Monitoring Plan

In accordance with the provisions of NTL 2008

- G06 , Remotely Operated Vehicle Surveys in De ep water

, Mississippi Canyon 525 is located in Grid 17 . Grid 17 is an area that does not have adequate ROV survey coverage; therefore the pre

- and pos t

- ROV survey will be run in accordance with the NTL.

Survey No. 1 will be conducted using the Rig based ROV equipped with video imaging capabilities prior to commencing operations on the well. The survey pattern will consist of six transects centered on the existing well with tracks extending 100 meters away from the well on bearings of 30°, 90°, 150°, 210°, 270°, and

330°. The seafloor will be videotaped continuously along each track and close

- up footage recorded of any animals or features. An identical survey will be conducted following drilling operations but prior to moving the rig off location. During both surveys, all biological an d physical observations will be documented using

Form MMS

- 141. Complete documentation, including videotapes, of both surveys will be submitted to the GOMR within 60 days of the final survey.

H. Threatened and Endangered Species Information

There are 5 sp ecies of sea turtles that may be found in the Gulf of Mexico (see table below ). No critical habitat for these species has been designated in the Gulf of Mexico.

Common Name Scientific Name T/E Status

Hawksbill Turtle Eretmochelys imbricata E

Green Turtle Chelonia mydas T
Kemp's Ridley Turtle Lepidochelys kempii E

Leatherback Turtle Dermochelys coriacea E
Loggerhead Turtle Caretta caretta TThere are 2 9 species of marine mammals that may be found in the Gulf of Mexico (see table below ). Of the

species listed as Endangered, only the Sperm whale is commonly found in the project area. No critical habitat for these species has been designated in the Gulf of Mexico.

Common Name Scientific Name T/E Status
Atlantic Spotted Dolphin Stenella frontalis

Blainville's Beaked Whale Mesoplodon densirostris

Blue Whale Balaenoptera musculus E
Bottlenose Dolphin Tursiops truncatus
Bryde's Whale Balaenoptera edeni
Clymene Dolphin Stenella clymene

Cuvier's Beaked Whale Ziphius cavirostris
Dwarf Sperm Whale Kogia simus

False Killer Whale Pseudorca crassidens

Fin Whale Balaenoptera physalus E
Fraser's Dolphin Lagenodelphis hosei

Gervais' Beaked Whale Mesoplodon europaeus
Humpback Whale Megaptera novaeangliae E

Killer Whale Orcinus orca

Melon

- headed Whale Peponocephala electra

Minke Whale Balaenoptera acutorostrata
Northern Right Whale Eubalaena glacialis E
Pantropical Spotted Dolphin Stenella attenuata
Pygmy Killer Whale Feresa attenuata
Pygmy Sperm Whale Kogia breviceps
Risso's Dolphin Grampus griseus
Rough

- toothed Dolphin Steno bredanensis

Sei Whale Balaenoptera borealis E

Short

- finned Pilot Whale Globicephala macrorhynchus
Sowerby's Beaked Whale Mesoplodon bidens
Sperm Whale Physeter macrocephalus E
Spinner Dolphin (Long

- snouted) Stenella longirostris
Striped Dolphin Stenella coeruleoalba

West Indian manatee Trichechus manatus E

Section 1 8 of this plan discusses potential impacts and mitigation measures related to threatened and endangered species.

I. Archaeological Report

Report Information

An archaeological report was generated by C&C Technologies for the area. The report is AUV Hazard Study, Blocks 479, 780, 481, 523, 524, 525, 567, 568, 569, 611, 612 & 613, Mississippi Canyon Area, Project

#08392 6

- 08483, February 2009.

Archaeological Statement

One hundred thirty

- seven (137) unidentified sonar contacts , including two debris zones, were recorded in the survey area. These sonar contacts are relatively small and could be debris related to modern shipping activities in the area. Anchor and anchor mooring for any proposed well drilling should avoid the locations of any existing pipelines and sonar contacts due to potential entanglement.

Shell will comply with all conditions of NTL 2005

- G07

.J. Air a nd Water Quality Information

Pursuant to NTL 2008

- G04 the proposed operations covered by this EP do not require Shell to provide additional information relating to air and water quality information. For specific information relating to air and water qual ity information please refer to the EIA , Attachment 18

.

K. Socioeconomic Information

Pursuant to NTL 2008

- G04 the proposed operations covered by this EP do not require Shell to provide additional information relating to air and water quality information. For specific information relating to socioeconomic information please refer to Section 18 of this Plan

.SECTION 7 : WASTE AND DISCHARGE INFORMATION

A. Discharge to GOM or DownholeB. Land, inject, incinerator or recycle table

C. Modeling Report

Shell did not model the trajectory for discharges because it is not required in the GOM

.SECTION 8: AIR EMISSIONS INFORMATION

A. Emissions Worksheet and 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 (whe re D distance to shore in miles)? x

Do your emission calculations include any emission reduction measures or

modified emission factors? x

Are your proposed exploration activities located east of 87.5° W longitude? x Do you expect to encounter H 2 S at concentrations greater than 20 parts per million (ppm)? x

Do you propose to flare or vent natural gas for more than 48 continuous hours From any proposed well? x

Do you propose to burn produced hydrocarbon liquids? x

B. If you answer no to all of the above screening questions from the appropriate table, provide:

(1) Summary information regarding the peak year emissions for both Plan Emissions and Complex Total Emissions, if applicable. This information is compiled on the summary form of the two

s ets of worksheets. You can submit either these summary forms or use the format below. You

do not need to include the entire set of worksheets.

Air Pollutant Plan

Emission 1

Amounts (tons) Calculated

Exemption 2

Amounts (tons) Calculated

Complex Total

Em ission

Amounts 3

(tons)

PM

SO
x NOx

VOC

CO

1 For activities proposed in your EP or DOCD, list the projected emissions calculated from the worksheets.

2 List the exemption amounts for your proposed activities calculated by using the formulas in 30 CFR 250.303(d).

3 List the complex total emissions associated with your proposed activities calculated from the worksheets

(2) Contact: Tracy Albert

, 504.728.4652

, tracy.albert @shell.com

(1) Worksheets

W orksheets are included in this plan.SECTION 9 : OIL SPILL S INFORMATION

A. Oil Spill Response Planning

All the proposed activities and facilities in this EP will be covered by the Regional OSRP filed by Shell Offshore Inc (0689) in accordance with 30 CFR 250. An update to the Regional OSRP was filed with the

BOEM October 26, 2010, March 15, 2011, May 31, 2011

, July 6, 2011 and August 1, 2011 is pending

approv al. An updated OSRP Certification in accordance with 30 CFR 254.2 was accepted by the BOEM on August 4 , 2011

.

Spill Response Sites: Primary Response Equipment Locations Preplanned Staging Location(s)
Venice, LA; Houma, LA; Pascagoula, MS;

Fort Jackson, LA Fourchon, LA; Pascagoula, MS; Fort Jackson, LA; Venice, LA

The names of the oil spill removal organizations (OSRO‘s) under contract include Clean Gulf Associates (CGA), Marine Spill Response Company (MSRC), Clean Caribbean America (CCA), and OSRL/EARL.

Worst Case Scenario Determination : Category Regional OSRP EP

Type of Activity 1 Drilling Rig Drilling Rig

Facility Location (area/block) MC 807 MC 525
Facility Designation 2 Subsea well A ◊ Subsea well C
Distance to Nearest Shoreline (miles) 5 3 79

Volume 3

Storage tanks (total)
Flowlines (on facility)
Pipelines
Uncontrolled blowout (volume per day)

Total Volume N/A
N/A

N/A

4 65 ,000 * BOPD

4 65 ,000 Bbls N/A
N/A

N/A

271 ,000* * BOPD

271 ,000 Bbls
Type of Oil(s)

- (crude oil, condensate,
diesel) Crude oil Crude oil

API Gravity(s) 4 2 6 o 39 o

*24 hour rate ( 3 6 5 ,000 BOPD 30 day average)

* *24 hour rate ( 9 2 ,000 BOPD 30 day average)

◊ MC 807 Subsea Well A was submitted as subsea WCD in our OSRP update of August 1, 2011 and was

covered for 2010

- N06 in Plan S

- 7499 ( approved November 22, 2011 ).

Footnotes:
1. Types of activities include pipeline, platform, caisson, subsea completion or manifold, and mobile drilling rig. 2. E.g., Well No. 2, Platform JA, Pipeline Segment No. 6373. 3. Your regional OSRP worst

- case scenario volume must be taken from the appropriate section of your regional OSRP. For EP‘s, the

worst

- case scenario volume must be determined by using the daily worst

- case discharge volume determined using the guidance at 30 CFR 254.47(b). For DOCD‘s, the daily worst

- case discharge volume must be determined by using the guidance at 30 CFR 254.47 (a) and/or (b), as appropriate. 4. Provide API gravity of all oils given under ―Type of Oil(s)‖ above. Estimate for EP‘s.

Si nce Shell Offshore Inc

. has the capability to respond to the appropriate worst

- case spill scenario included in its regional OSRP, filed with the BOEM October 26, 2010, March 15, 2011, May 31, 2011

, July 6, 2011 and August 1, 2011 and is pending approval , a nd since the worst

- case scenario determined for our Plan does not replace the appropriate worst

- case scenario in our regional OSRP, I hereby certify that Shell Offshore Inc

. has the capability to respond, to the maximum extent practicable, to a worst

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

.B. Oil Spill Response Discussion

1

. Volume of the Worst Case Discharge

Please refer to Section 2j of this EP

2. Trajectory Analysis

Trajectories of a spill and the probability of it impacting a land segment have been projected utilizing information in the BOEM Oil Spill Risk Analysis Model (OSRAM) for the Central and Western

Gulf of Mexico available on the BOEM website using 30 day imp act. Offshore areas along the trajectory between the source and land segment contact could be impacted. The land segment contact probabilities are shown in Table 9. B .1.

Area/Block OCS

- G Launch

Area Land Segment Contact %

Exploratory

MC525 31507 57 Matagorda, TX

- Galveston, TX

- Jefferson, TX

- Cameron, LA 1 Vermilion, LA 1 Iberia, LA

- Terreboone, LA 2 Lafourche, LA 2 Jefferson, LA

- Plaquemines, LA 21 St. Benard, LA 3 Hancok & Harrison, MS 1 Jackson, MS 1 Mobile, AL 1 Baldwin, AL 1 Escambia, FL 1 Okaloosa, FL 1
Walton, FL 1
Bay. FL 1
Franklin, FL

-

Table 9. B .1 Probability of Land Segment Impact

C. Resource Identification

The locations identified in Table 9. B .1 are the highest probable land segments to be impacted using

the BOEM Oil Spill Risk Analysis Model (OSRAM). The environmental sensitivities are identified using the appropriate National Oceanic and Atmospheric Administration (NOAA) Environmental Sensiti vity Index (ESI) maps for the given land segment. ESI maps provide a concise summary of coastal resources that are at risk if an oil spill occurs nearby. Examples of at

- risk resources include biological resources (such as birds and shellfish beds), sensiti ve shorelines (such as marshes and tidal flats),

and human

- use resources (such as public beaches and parks).

In the event an oil spill occurs, ESI maps can help responders meet one of the main response objectives: reducing the environmental consequences o f the spill and the cleanup efforts. Additionally, ESI maps can be used by planners to identify vulnerable locations, establish protection priorities, and identify cleanup strategies.

The following is a list of resources of special economic or environment al importance that potentially could be impacted by the Mississippi Canyon 525 WCD scenario.Onshore/Nearshore: Plaquemines Parish has been identified as the most probable impacted

Parish within the Gulf of Mexico for the Greater than 10 Mile Worst Case Discharge and the Exploratory Worst Case Discharge. The Plaquemines Parish has a total area of 2,429 square miles of which, 845 square miles of it is land and 1,584 square miles is water. The Plaquemines Parish includes two National Wildlife Refuges: Bret on National Wildlife Refuge and Delta National Wildlife Refuge. This area is also a nesting ground for the brown pelican, an endangered species. Examples of Environmental Sensitivity maps for Plaquemines Parish are detailed in the following pages. Key

ESI maps for Plaquemines Parish and the legend are shown in Figures 9.C.1 through 9.C.5.

Offshore: An offshore spill may require an Essential Fishing Habitat (EFH) Assessment. This assessment would include a description of the spill, analysis of the potential adverse effects on EFH and the managed species; conclusions regarding the effects on the EFH; and proposed mitigation, if applicable.

Significant pre

- planning of joint response efforts was undertaken in response to provisions of the National Contingency Plan (NCP). Area Contingency Plans (ACPs) were developed to provide a well coordinated respons e to oil discharges and other hazardous releases. The One Gulf Plan is specific to the Gulf of Mexico to advance the unity of policy and effort in each of the Gulf Coast ACPs. Strategies used for the response to an oil spill regarding protection of identif ied resources are

detailed in the One Gulf Plan and relevant Gulf Coast ACP.

D. Worst Case Discharge Response

Shell will make every effort to respond to the MC 525 Worst Case Discharge as effectively as possible. Applied Science Associates (ASA) conducted a deepwater blowout simulation for The Response Group to better determine subsurface and surface evaporation a nd dispersion rates. Below is a table outlining the applicable evaporation and dispersion quantities

.

Mississippi Canyon 525 Calculations

(BBLS)

i. 30 Day Average WCD = 233 ,000 bbls

ii. Subsurface dispersion

– 25% (Water Depth = ~7,50 5 ft)

- 58

, 25 0 bbls

iii. REMAINING WCD AFTER SUBSURFACE DISPERSION 174,750 bbls

iv. Surface dispersion and evaporation

– 25%

- 43,687 bbls

TOTAL REMAINING ~51,800 bbls

Table 9.D.1 Oil Remaining After Subsurface and Surface Dispersion

Shell has contracted OSROs to provide equipment, personnel, materials and support vessels as well as temporary storage equipment to be considered in order to cope with a WCD spill. Under adverse weather conditions, major response vessels and Transrec skimm ers are still effective and safe in sea

states of 6

- 8 ft. If sea conditions prohibit safe mechanical recovery efforts, then natural dispersion and airborne chemical dispersant application (visibility & wind conditions permitting) may be the only safe and v iable recovery option.

MSRC OSRV 8 foot seas
VOSS System 4 foot seas Expandi Boom 6 foot seas, 20 knot winds Dispersants Winds more than 25 knots, Visibility less than 3 nautical miles, or Ceiling less than 1,000 feet.

Table 9.D.2 Operational Limitations of Response Equipment

Upon notification of the spill, Shell would request a partial or full mobilization of contracted resources, including, but not limited to, skimming vessels, oil storage vessels, dispersant aircraft, subsea dispersant, sho reline protection, wildlife protection, and containment equipment. Following is a list of the contracted resources including de

- rated recovery capacity, personnel, and estimated response times (procurement, load out, travel time to the site, and deploymen t). The IncidentCommander or designee may contact other service companies if the Unified Command deems such

services necessary to the response efforts.

Based on the anticipated worst case discharge scenario, Shell can be onsite with dedicated, contracted on water oil spill recovery equipment with adequate response capacity to contain and recover surface oil, and prevent land impact, within 30 hours (based on the equipment‘s Estimated Daily Response Capacity (EDRC)). Shell will continue to ramp up additional on

- water mechanical recovery resources as well as apply dispersants and in

- situ burning as needed and as approved under the supervision of the USCG Ca ptain of the Port (COTP) and the Regional Response Team (RRT).

Subsea Control and Containment: Shell, as a founding member of the MWCC, will have access to the IRCS that can be rapidly deployed through the MWCC. The IRCS is designed to contain oil

flow in the unlikely event of an underwater well blowout, and is designed, constructed, tested, and available for rapid response. Shell‘s specific containment response for MC 525 will be addressed in

Shell‘s NTL 2010

- N 10 submission at the time the APD is submitte d.

Mechanical Recovery (skimming): Response strategies include skimming utilizing available OSROs Oil Spill Response Vessels (OSRVs), Oil Spill Response Barges (OSRBs), ID Boats, and Quick

Strike OSRVs. There is a combined de

- rated recovery rate capabilit y of approximately 323,500 barrels/day. Temporary storage associated with the identified skimming and temporary storage equipment equals approximately 297,900 barrels.

De

- rated Recovery Rate (bopd) Storage (bbls) Offshore Recovery and Storage 269,031 293,000 Nearshore Recovery and Storage 54,470 4,924

Total 323,501 297,924

Table 9.D.3 Mechanical Recovery Combined De

- Rated Capability

Table 9.D.4 Offshore On

- Water Recovery and Storage Activation List

Table 9.D. 5 Nearshore On

- Water Recovery and Storage 5ctivation List

Oil Storage: The strategy for transferring, storing and disposing of oil collected in these recovery zones is to utilize two 150,000

- 160,000 ton (dead weight) tankers mobilized by Shell (or any other tanker immediately available). The recovered oil would be transferred to Motiva‘s Norco, LA storage and refining facility, or would be stored at Delta Commodities, Inc. Harvey, LA facility.

Aerial Surveillance: Aircraft can be mobilized to detect, monitor, and target response to oil sp ills. Aircraft and spotters can be mobilized within hours of an event.

Table 9.D.6 Aerial Surveillance Activation List

Aerial Dispersant: Depending on proximity to shore and water depth, dispersants may be a viable response option. If appropriate and approved, 4 to 5 sorties from three DC

- 3‘s can be made within the first 12 hour operating day of the response. These aerial systems could disp erse approximately 7,704 to 9,630 barrels of oil per day. Additionally, 3 to 4 sorties from the BE90 King Air and 3 to 4

sorties from the Hercules C

- 130A within the first 12 hour operating day of the response could disperse 4,600 to 6,100 barrels of oil pe r day. For continuing dispersant operations, the CCA‘s Aerial Dispersant Delivery System (ADDS) would be mobilized. The ADDS has a dispersant spray capability of 5,000 gallons per sortie.

Table 9.D.7 Offshore Aerial Dispersant Activation ListVessel Dispersant: Vessel dispersant application is another available response option. If

appropriate, vessel spray systems can be installed on offshore vessels of opportunity using inductor nozzles (installed on fire

- water monitors), skid mounted systems, or pur pose

- built boom arm spray systems. Vessels can apply dispersant within the first 12

- 24 hours of the response and continually as

directed.

Table 9.D.8 Offshore Boat Spray Dispersant Activation List

Subsea Dispersant: Shell has contracted with Wild Well C ontrol for a subsea dispersant package. Subsea dispersant application has been found to be highly effective at reducing the amount of oil reaching the surface. Additional data collection, laboratory tests and field tests will help in facilitating the optim al application rate and effectiveness numbers. For planning purposes, the system has the potential to disperse approximately 24,500 to 34,000 barrels of oil per day.

Table 9.D.9 Control, Containment, and Subsea Dispersant Package Activation List

In

- Sit u Burning: Open

- water in

- situ burning (ISB) also may be used as a response strategy, depending on the circumstances of the release. ISB services may be provided by the primary OSRO contractors. If appropriate conditions exist and approvals are granted, one or multiple ISB task forces could be deployed offshore. Task forces typically consist of two to four fire teams, each with two vessels capable of towing fire boom, guide boom or tow line with either a handheld or aerially

deployed oil ignition system. At least one support/safety boat would be present during active burning operations to provide logistics, safety and monitoring support. Depending upon a number of factors, up to 4 burns per 12

- hour day could be completed per ISB fire team. Most fire boom
syst ems can be used for approximately 8

- 12 burns before being replaced. Fire intensity and weather will be the main determining factors for actual burns per system. Although the actual amount of oil that will be removed per burn is dependent on many factors, r ecent data suggests that a typical burn might eliminate approximately 750 barrels. For planning purposes and based on the above assumptions, a single task force of four fire teams with the appropriate weather and safety conditions could complete four burns per day and remove up to ~12,000 bbls/day. In

- situ burning nearshore and along shorelines may be a possible option based on several conditions and with appropriate approvals, as outlined in Section 19, In

- situ Burn Plan (OSRP). In

- situ burning along

certa in types of shorelines may be used to minimize physical damage where access is limited or if it is determined that mechanical/manual removal may cause a substantial negative impact on the environment. All safety considerations will be evaluated. In additio n, Shell will assess the situation and can make notification within 48 hours of the initial spill to begin ramping up fire boom production through contracted OSRO(s). There are potential limitations that need to be assessed prior to ISB operations. Some li mitations include atmospheric and sea conditions; oil weathering; air quality impacts; safety of response workers; and risk of secondary fires.

Table 9.D.10 In

- Situ Burn Equipment Activation List

Shoreline Protection: If the spill went unabated, shorel ine impact in Plaquemines Parish, LA would depend upon existing environmental conditions. Nearshore response may include the deployment of shoreline boom on beach areas, or protection and sorbent boom on vegetated areas. Strategies would be based upon surv eillance and real time trajectories provided by The Response Group that depict areas of potential impact given actual sea and weather conditions. Strategies from the New Orleans, Louisiana Area Contingency Plan, Unified Command would be consulted to ensure that environmental and special economic resources would be correctly identified and prioritized to ensure optimal protection. Shell has access to shoreline response guides that depict the protection response modes applicable for oil spill clean

- up operati ons. Each response mode is schematically represented to show optimum deployment and operation of the equipment in areas of environmental concern. Supervisory personnel have the option to modify the deployment and operation of equipment allowing a more effe ctive response to site

- specific circumstances.

Table 9.D.11 Shoreline Protection and Wildlife Support List

Wildlife Protection: If wildlife is threatened due to a spill, the contracted OSRO‘s have resources available to Shell, which can be utilized to p rotect and/or rehabilitate wildlife. The resources under contract for the protection and rehabilitation of affected wildlife are in Table 9.D.11.New or unusual technology in regards to spill, prevention, control and clean

- up:

Shell will use our normal well design and construction processes with multiple barrier approach as well as new stipulations mandated by NTL 2008

- N05 . Response techniques will utilize new learnings from Macondo response to include in

- situ burning and subsea disp ersant application. Mechanical recovery advancements are continuing to be made to incorporate utilization of Koseq arms outfitted on barges, conversion of Platform Support Vessels for Oil Spill Response, and inclusion of nighttime spill detection radar to improve tracking capabilities (X

- Band radar, Infrared sensing, etc.). In addition, new response technologies/techniques are continuing to be considered by Shell and the appropriate government organizations for incorporation into our planned response. Any additional response technologies/techniques presented at the time of response will be used at the discretion of

the Unified Command and USCG.

D. Modeling Report

Shell did not model oil or hazardous substance spills.Figure 9.C.1 Environmental Sensitivity Index Map LegendFigure 9.C.2 South Pass ESI MapFigure 9.C.3 Garden Island Pass ESI Map.

Figure 9.C.4 Pass a Loutre West ESI MapFigure 9.C.5 Main Pass ESI Map

### Table 9.D. 4 Offshore On

- Water Recovery and Storage Activation List

### Table 9.D.4 Offshore On

- Water Recovery and Storage Activation List (continued)

Table 9.D.4 Offshore On

- Water Recovery and Storage Activation List (continued)

### Table 9.D.5 Nearshore On

- Water Recovery and Storage Activation List

### Table 9.D.5 Nearshore On

- Water Recovery and Storage Activation List (continued)

Table 9.D. 6 Aerial Surveillance Activation List

### Table 9.D.7 Offshore Aerial Dispersant Activation List

Table 9.D.8 Offshore Boat Spray Dispersant Activation List

### Table 9.D.9 Control, Containment, and Subsea Dispersant Package Activation List

### Table 9.D.10 In

- Situ Burn Equipment Activation List

### Table 9.D.10 In

- Situ Burn Equipment Activation List (continued)

Table 9.D.11 Shoreline Protection and Wildlife Support ListSECTION 10 : ENVIRONMENTAL MONITORING INFORMATION

A. Monitoring Systems

A rig

- based Acoustic Doppler Current Profiler (ADCP) is used to continuously m onitor the current beneath

the R ig. Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously

monitored

.

B. Incidental Takes

No incidental takes are anticipated. Shell implements the mitigation measures and monitors for incidental takes of protected species according to the following notices to lessees and operators from the Minerals Management Service:

NTL 2007

- G03 ―Marine Trash and Debris Awareness and Elimination‖

NTL 2007

- G04 ―Vessel Strike Avoidance and Injured/Dead Protected Species Reporting‖

C. Flower Garden Banks National Marine Sanctuary

The operations proposed in this EP will not be conducted within the Protective Zones of the Flower Garden

Banks and Stetson Bank.SECTION 11 : LEASE STIPULATIONS INFORMATION

Lease OCS

- G 31507 was acquired in Lease Sale #205 with an effective date of March 1, 2008. The Lease is in its primary term and will expire February 28, 2018.

Stipulation No. 3

– Military Areas
This lease is not in the Water Test Area of the Eglin Water Test Area 1. Shell will hold and save harmless the U.S. Government, its contractors and subcontractors, or any of its officers, agents or employees with regard to this Lease. Electromagnetic emissions will be conducted as to not interfere with the Depart ment of Defense operations. Shell will enter into an agreement with the commander of the Air Armament Center in Eglin AFB, Florida, when operating boats, ships and aircraft traffic in the designated warning area.

Stipulation No. 8

– Protected Species This Stipulation is addressed in the following sections of this plan: Section 6h, Threatened or endangered species, critical habitat, and marine mammal information Section 10b, Environmental Monitoring Information, Incidental takes Section 12b, Environment al Mitigation Measures Information, Incidental takes Section 18, Environmental Impact Assessment

SECTION 12 : ENVIRONMENTAL MITIGATION MEASURE INFORMATION

A. Impacts to Marine and coastal environments

The proposed action will implement mitigation measures required by laws and regulations, including all applicable Federal and State requirements concerning air emissions, discharges to water, and solid waste disposal, as well as any additional permit requirements and Shell policies. Project activities will be conducted in accordance with the Regional Oil Spill Response Plan. Section 18 of this plan discusses impacts and mitigation

measures.

B. Incidental Takes

We do not anticipate any incidental takes related to the proposed operations. Shell implements the mitigation measures and monitors for incidental takes of protected species according to the following notices to lessees and operators from the BOEM :

NTL 2 007

- G03 ―Marine Trash and Debris Awareness and Elimination‖

NTL 2007

- G04 ―Vessel Strike Avoidance and Injured/Dead Protected Species Reporting‖

SECTION 13 : RELATED FACILITIES AND OPERATIONS INFORMATION

Information regarding Related Facilities and Operati ons Information , transportation systems, & produced liquid hydrocarbon transportation vessels are not included in this EP as such information is only necessary in the case of

DOCDs.SECTION 14: SUPPORT VESSELS AND AIRCRAFT INFORMATION

A. General

Type Maximum Fuel Tank

Storage Capacity (Gals) Maximum No. In Area at Any Time Trip Frequency or

Duration

Crew Boats 8,000 2 Twice per week Offshore Support Vessels 120,000 3 Twice per week Helicopter 764 1 Once per day

B. Diesel Oil Supply Vessels

Size of Fuel Supply

Vessel Capacity of Fuel Supply

Vessel Frequency of Fuel

Transfers Route Fuel Supply Vessel Will

Take

280 foot length 100,000 gals. 1 week Port Fourchon to MC 525

C. Drilling Fluids Transportation

This Plan does not propose activities in the State of Florida; therefore the following table is not required. It is being provided for information only.

Type of Material Quantity Being Transported Transportation Method Dry Bulk (Cement, Barite, Gel) 12,000 sx max combined Below deck dry bulk tanks

onboard OSV Synthetic

- base drilling fluids 11,000 bbls max per voyage Drums on Company's supply

boat Water Based drilling fluids 12,000 bbls max per voyage Below deck liquid mud tanks

onboard OSV

D. Solid and Liquid Wastes Transportation

See Section 7, Table 7B.

E. Vicinity Map

See Attachment 14

- A for vicinity map

.SECTION 15 : ONSHORE SUPPORT FACILITIES INFORMATION

A. General

Name Location Existing/New/Modified

Fourchon Port Fourchon, LA Existing

Amelia PHI Heliport Amelia LA Existing

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

Fouchon , Louisiana. The Fouchon boat facility is operated by SOI and is located on Bayou Lafourche

, south of Leeville, LA approximately 3 miles from the Gulf of Mexico. The existing onshore air support base in Amelia, LA is located at 4008 Lake Palourde Road, Amelia , LA 703 40

.

B. Support Base Construction or Expansion

This Section does not apply to this EP as Shell does not plan to construct a new onshore support base or expand an existing one to accommodate the activities proposed in this EP

.

C. Support Base Construction or Expansion Timetable

This Section does not appl y to this EP as Shell does not plan to construct a new onshore support base or expand an existing one to accommodate the activities proposed in this EP

.

D. Waste Disposal

See Section 7, Tables 7A and 7B for water disposal

.

E. Air emissions

Not required by BOEM GOM.

F. Unusual solid and liquid wastes

Not required by BOEM GOM.

SECTION 16 : SULPHUR OPERATIONS INFORMATION

Information regarding Sulphur Operations Information is not included in this EP as we are not proposing to conduct sulphur operations.SECTION 17 : COASTAL ZONE MANAGEMENT ACT (CZMA) INFORMATION

LOUISIANA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

INITI AL EXPLORATION PLAN

Type of Plan

MISSISSIPPI CANYON Block 525

Area and Blocks

OCS

- G 31507

Lease Number

The proposed activities described in detail in this Plan will comply with Louisiana's State and Local Coastal Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management

Enforceable Policies.

We have considered all of Louisia na's Enforceable Policies in making this certification of consistency.

SHELL OFFSHORE INC. Operator

_____________________________________________

Sylvia A. Bellone Certifying Official

9/ 30 /2011

DateALABAMA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

INITIAL EXPLORATION PLAN

Type of Plan

MISSISSIPPI CANYON Block 525

Area and Blocks

OCS

- G 31507

Lease Number

The proposed activities described in detail in this Plan will comply with Alabam a's State and Local Coastal Resources Management Act of 1978, Coastal Resources Program, and Coastal Area Management

Enforceable Policies.

We have considered all of Louisiana's Enforceable Policies in making this certification of consistency.

SHELL OFFSHORE INC.

Operator

____________________________________________

Sylvia Bellone Certifying Official

9/ 30 /2011

DateCoastal Zone Management Consistency Information

For the State of Alabama

In accordance with 30 CFR 250.2 2 6(a) and (b)

, Shell Offshore Inc. (SOI) is hereby providing the following information in support of Section 18 ( Environmental Impact Analysis ) of our Exploration Plan for

this lease

.

The regulations found in 15 CFR 930.58 identifies necessary data and infor mation to be furnished to the State agency. The information is as follows:

A. CONSISTENCY CERTIFICATION

A Coastal Zone Consistency Certification for activities that affect the State of Alabama is provided in Section 17 of this EP

.

B. OTHER INFORMATION

(1) Shell Offshore Inc

. shall utilize a shore base in Fourchon, Louisiana for water support and PHI‘s Amelia terminal for air traffic for the proposed activities.

(2) As per NTL 200 8

- G 04 , the following items have been identified as being required:

 A discus sion of the method of disposal of wastes and discharges is provided in Section 7

of this EP

.

 Oil Spill Information is provided in Section 9 of this EP

.

 All operations are covered by Shell Offshore Inc.‘s Regional Oil Spill Response Plan, which

has been up dated and is pending approval by BOEM . The Plan is available upon request.

(3) Following is an evaluation that includes findings relating the coastal effects of the proposed activities and associated facilities to the relevant enforceable policies of the Alabama‘s Coastal Management Program:

All activities sha ll be consistent with Alabama‘s coastal management program and shall comply with all relevant rules and regulations. Pollution shall be prevented or reduced at the source; pollution that cannot be prevented shall be recycled in an environmentally safe manner; pollution that cannot be prevented or recycled shall be treated in an environmentally safe manner; and disposal or other release into the environment shall be employed only as a last resort an d should be conducted in an environmentally safe manner. All activities comply with all applicable provisions of the administrative code. No activities are planned within special management areas. Activities will be carried out avoid unnecessary

conflict s with other uses of the vicinity.

COASTAL RESOURCE USE POLICIES

Coastal Development

– All activities shall be conducted in a manner that minimizes significant impacts to coastal resources. No adverse effects to Alabama‘s coastal area are expected in

as sociation with the proposed activities.

Mineral Resource Exploration and Extraction

– No conflicts with any other mineral resource exploration and extraction are expected.Commercial Fishing

– All uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicable adverse disruptions to fishery migratory patterns.

Hazard Management

- Effective emergency plans are in place, practiced, and updated as necessary. The best practical techniqu es shall be utilized to prevent the release of pollutants

or toxic substances into the environment.

Shoreline Erosion

- All uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicab le adverse alteration of protective coastal features

Recreation

– We have considered the general factors utilized by permitting authorities and have determined that the proposed activities shall cause no adverse impacts on areas of public use or concern, and all uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicable adverse alteration of these areas. The MMS has regulations in place which explicitly prohibit the disposal of equi pment, cables, chains, chains, containers or other materials which may pose an unreasonable risk to public health, property, aquatic life, wildlife, recreation, navigation, commercial fishing, or other uses of the ocean into offshore waters. Although mari ne debris gets lost from time to time, the impact on Gulf Coast recreational beaches is expected to be minimal. No impacts are expected to adversely affect Public access to tidal and submerged lands, navigable waters and beaches or other public recreation al resources.

Transportation

- Alabama‘s transportation resources are not expected to be impacted, as

shore bases in Fourchon and Amelia, Louisiana will be utilized for the proposed operations. Also, boats will not travel through any sensitive coastal are as off of the coast of Alabama.

NATURAL RESOURCE PROTECTION POLICIES

Biological Productivity

- All uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicable adverse alteration of biologically valuable areas. All uses and activities shall be planned, sited, designed,

constructed operated and maintained to avoid to the maximum extent practicable reductions in long

- term biological productivity of the coastal ecosystem. No impacts are expected to adversely affect the biological productivity of the area.

Water Quality

- The proposed activities shall be carried out in conformance with applicable

wa ter quality laws, standards, and regulations. All discharges shall be covered by an NPDES permit. There shall be no discharge of untreated produced water, drilling muds, or cuttings resulting from energy exploration and production activities to the coas tal waters of Alabama. Produced waters that are discharged offshore are diluted and dispersed to very near background levels at a distance of 1,000 m and are undetectable at a distance of 3,000 m from the discharge point. The MMS regulations, the USEPA‘s NPDES general permit, and the USCG regulations implementing MARPOL 73/78 Annex V prohibit the disposal of any trash

and debris into the marine environment.

Water Resources

- All uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicable detrimental discharges

into coastal waters.

Air Quality

- The proposed activities shall be carried out in conformance with applicable air quality laws, standards, and regulations. Emissions from the proposed activities are notexpected to have significant impacts on onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of these

emissions from the coastline.

Wetlands and Submerged Grass beds

- All uses and activities shall be planned, sited, designed, constructed operated and maintained to avoid to the maximum extent practicable reductions of natural circulation patterns within or into wetlands and submerged grass beds. Pipeline a nd navigation canals are considered the most significant impacting factors to wetlands and neither is proposed in the DOCD. Proposed activities are not expected to have any adverse impact on sea grass communities.

Beach and Dune Protection

- Effective environmental protection plans are in place, practiced, and updated as necessary. No significant impacts to the physical shape and structure of barrier beaches and associated dunes are expected to occur. In the unlikely event of a spill

contac ting a barrier beach, sand removal during cleanup would be minimized.

Wildlife Habitat Protection

- We have considered the general factors utilized by permitting authorities and have determined that the proposed activities shall cause no adverse impacts on wildlife habitat areas. All uses and activities shall be planned, sited, designed, constructed

op erated and maintained to avoid to the maximum extent practicable adverse alteration of wildlife habitats or coastal wildlife. Proposed activities are in OCS waters, so they are located away from critical wildlife and vegetation areas. Access routes from shore base operations shall pose no adverse on these critical wildlife and vegetation areas.

Endangered Species No impacts are expected to adversely affect wildlife and fishery habitat, especially the designated Critical Habitats of Endangered Species

.

Beach mice

– Potential impacts include oil spills, oil

- spill response activities, consumption of beach trash and debris and coastal habitat degradation. No significant impacts to beach mice are expected to occur. Protective measures required under the Endangered Species Act should prevent any oil

- spill response and cleanup activities from having significant impact to

beach mice and their habitat.

Marine birds

– Potential impact

- producing factors for marine birds in the offshore environment

include hel icopter and service vessel traffic and noise, air emissions, degradation of water quality, habitat degradation, and ingestion discarded trash and debris from service vessels and OCS structures. Adverse impacts to endangered coastal and marine birds are e xpected

to be sublethal.

Sea turtles

– Potential impact

- producing factors from the proposed activities that may affect sea turtles include water quality degradation from operational discharges, noise from helicopter and vessel traffic and operating plat forms, vessel collisions, brightly lit platforms, and swallowing or getting tangled in OCS

- related trash and debris. Routine activities are expected to be sublethal and unlikely to have significant adverse effects on the size and recovery of any sea turtl e species or population in the Gulf of Mexico.

Sturgeon

– Drilling mud discharges may contain chemicals toxic to sturgeon, at concentrations four or five orders of magnitude higher than concentrations found a few meters from the discharge point. These di scharges dilute to background levels within 1000m of the discharge point. No impacts from the proposed activities are expected.Cultural Resources Protection

- All uses and activities shall be planned, sited, designed, constructed operated and maintai ned to avoid to the maximum extent practicable adverse alteration of cultural resources. No impacts are expected to adversely affect historical, architectural, or archaeological sites. Should any historical, architectural, or archaeological

resource be d iscovered in the course of conducting authorized activities, the Alabama Department of Environmental Management and the Alabama State Historical Officer shall be

notified.SECTION 18 : ENVIRONMENTAL IMPACT ANALYSIS (EIA)

1.0 Introduction

1.1 Project Summary

Shell Offshore Inc. (Shell) is submitting an Initial Exploration Plan (EP) for Mississippi Canyon (MC)

Block 525, wells A, B, C, D, and E. This initial EP is being submitted pursuant to Lease Sale 205, which was approved by the U.S. Department of the Interior (USDOI), Minerals Management Service (MMS, now Bureau of Ocean Energy Management [BOEM]) on October 3, 2007. This Initial EP was prepared in

accordance with all BOEM regulations and Notice to Lessees and Operators (NTL), including NTL

2010

- N0 6 that requires an updated blowout scenario and calculation of the worst case discharge (WCD).

MC Block 525 is 79 statute miles 1 (127 kilometers [km]) from the nearest shoreline; 164 miles (264 km) from the onshore support base at Port Fourchon, Louisiana ; and 208 miles (167 km) from the helicopter base at Amelia, Louisiana ( Figure 1 ). The proposed wellsites are in water ranging from 7,400 to 7,600 feet (2,255 to 2,316 meters [m]) deep.

Shell proposes to use the Noble Globetrotter o r a similar dynamically positioned (DP) drillship for this project, beginning in the second quarter of 2012. The first well is expected to take 148 days to drill, and each additional well would take about 128 days to drill.

1.2 Purpose of the EIA

The purpose of this Environmental Impact Analysis (EIA) is to evaluate the potential effects of the proposed action on environmental resources in the project area. The EIA was prepared pursuant to the National Environmental Policy Act (NEPA) and other fed eral laws, including the Outer Continental Shelf Lands Act (OCSLA), the Endangered Species Act (ESA), the Marine Mammal Protection Act (MMPA), the Magnuson

- Stevens Fishery Conservation and Management Act (MSFCMA), and implementing regulations

associated wi th these laws.

Shell has prepared this EIA in accordance with NTL 2008

- G04 and subsequent guidance to provide necessary information to support BOEM ‘s approval of the Initial EP for proposed activities in MC Block

525.

1.3 Related Environmental Docume nts

NEPA regulations stipulate that broad programmatic Environmental Impact Statements (EIS) form the foundation used to tier more focused project

- specific analyses (40 Code of Federal Regulations [CFR.] § 1508.28). BOEM has prepared three broad EISs for oil and gas drilling activities in the project area: (1) Outer Continental Shelf Oil & Gas Leasing Program: 2007

- 2012 Final EIS (MMS 2007a), (2) the Multisale EIS ( Gulf of Mexico OCS Oil and Gas Lease Sales: 2007

- 2012; Western Planning Area Sales 204, 207, 210, 215, and 218; Central Planning Area Sales 205, 206, 208, 213, 216, and 222; Final EIS ) (MMS 2007b); and (3) the Multisale Supplemental EIS ( Gulf of Mexico OCS Oil and Gas Lease Sales: 2009

- 2012; Central Planning Area Sales 208, 213, 216, and 222; Wes tern Planning Area Sales 210, 215, and 218; Final Supplemental EIS [SEIS] ) (MMS 2008). In addition, BOEM has recently published a final SEIS for the Western Planning Area ( Gulf of Mexico OCS Oil and Gas Lease Sale: 2011; Western Planning Area

Lease Sale 2

18 Final Supplemental Environmental Impact Statement ) ( BOEM 2011a) that provides updates to the environmental conditions and impacts since the Deepwater Horizon (DWH) event. The 2011 SEIS provided a thorough analysis of conditions within the northern Gulf of Mexico that may have

1 All miles in the EIA are statute miles.changed after the DWH event. Many of the analyses and conclusions in the 2011 SEIS apply to the

northern Gulf of Mexico in general and are considered relevant to the proposed action in MC 525. To the

extent that the BOEM (2011a) SEIS addresses conditions that prevail within the project area for this proposed action, it is incorporated by reference.

MC 525 is in deepwater Grid 17; no Grid Environmental Assessment (EA) was prepared for Grid 17. However, a recently prepared site

- specific EA (SEA) for exploratory activities in nearby lease blocks is considered relevant to this EIA because it addresses similar work in the project vicinity ( BOEM 2011b). Moreover, the SEA includes information not available during the preparation of t he Multisale and Supplemental EISs (MMS 2007a, b; 2008), particularly with respect to the DWH event.

The purpose of tiering NEPA documents is to streamline or focus the project

- specific analysis on aspects of the proposed action (1) that differ from the o verall program, or (2) for which assumptions have changed since the programmatic documents were prepared. The purpose of NEPA analysis, which is to provide a thorough, transparent evaluation of potential project

- related impacts to resources, is best

serve d by smaller, simpler documents that focus directly on the relevant environmental issues. Wherever a programmatic EIS adequately addresses potential site

- specific impacts, it is incorporated by reference to avoid repetitive discussion.

The programmatic EISs evaluate the potential effects of leasing, exploration, development, and related activities on the environmental, archaeological, and socioeconomic resources of the Gulf of Mexico in general. Particular aspects of the living environment that may be a ffected by activities in the Outer Continental Shelf (OCS) include offshore benthic resources, fish and fisheries, sea turtles, coastal and marine birds, marine mammals, endangered and threatened species, and sensitive coastal environments. Over the past several decades, BOEM and others have conducted numerous technical studies focused on describing baseline conditions, predicting the outcome of routine operations and accidental releases, and developing mitigation measures to minimize adverse effects. Thr ough this process, BOEM has developed permit and lease stipulations, mitigation measures, and standard operating procedures and requirements that promote the protection of resources during exploration and development of offshore wells. This site

specific EIA incorporates OCS mitigation measures both implicitly and explicitly so that the proposed action can be carried out with minimal impact to the environment.

### Figure 1

. Project Location: MC 5251.4 OCS Regulatory Framework

As a regulatory agency of the USDOI, BOEM manages and regulates offshore activities as directed by OCSLA (30 CFR 250, 251, and 254). In addition to its regulatory function, BOEM manages the Environmental Studies Program, envis ioned in OSCLA as a mechanism to ―monitor the human, marine, and coastal environments of such area or region in a manner designed to provide time

- series and data trend information...‖ (Matthews and Cameron 2010; page 2). Ongoing environmental studies focus on oil spill trajectories, impacts of anchoring, sensitive chemosynthetic communities, and other aspects of OCS

activities.

Both OCSLA and NEPA require that BOEM consult or cooperate with other federal and state agencies with jurisdiction over public res ources. Federal laws requiring interagency cooperation include the Coastal Zone Management Act of 1972 (CZMA), the ESA of 1973, MSFCMA, and MMPA. The purpose of these laws is to ―encourage orderly, safe, and environmentally responsible development of oil , natural gas, and alternative energy sources on the OCS,‖ as described in the OCS Regulatory Framework for the Gulf of Mexico Region (Matthews and Cameron 2010, page 1). The BOEM interacts routinely with the U.S. Coast Guard (USCG), U.S. Environmental Pr otection Agency (EPA), U.S. Fish and Wildlife Service (FWS), and the National Oceanic and Atmospheric Administration (NOAA), specifically the National Marine Fisheries Service (NMFS).

The BOEM provides explicit instruction to operators through NTLs, whic h are ―formal documents that provide clarification, description, or interpretation of a regulation or OCS standard; provide guidelines on the implementation of a special lease stipulation or regional requirement; provide a better understanding of the scope and meaning of a regulation by explaining BOEM interpretation of a requirement; or transmit administrative information...‖ ( BOEM 2011c). Seven NTLs are considered pertinent to this EIA ( Table 1 ).

1.5 Oil Spill Prevention and Contingency Planning

Shell submitted an update to the Gulf of Mexico Regional Oil Spill Response Plan (OSRP) to the BOEM as a fundamental component of the planned drilling program. The OSRP certifies that Shell has the capability to respond to the maximum extent practicable to a WCD (30 CFR 254.2) (see Initial EP Section 9). The OSRP demonstrates Shell‘s capabilities to rapidly and effectively manage oil spills that may result from drilling operations.

A large oil spill is extremely unlikely to be asso ciated with the proposed action. However, Shell‘s OSRP provides contingencies for a range of spills, from small operational spills up to and including a WCD from a well blowout. Shell‘s OSRP demonstrates the capacity to respond to a large oil spill that exceeds the calculated WCD for the proposed action. Shell‘s OSRP meets or exceeds federal requirements and regulations of each of the potentially affected Gulf Coast states. The OSRP is incorporated by reference

to this EIA.

Shell has calculated a WCD f or this Initial EP, using the requirements prescribed by NTL 2010

- N06, as

271 ,000 barrels of oil per day (BOPD) for the first day with a 30

- day average of 233 ,000 BOPD. The detailed analysis of this calculation can be found in Initial EP Section 2j. The W CD scenario for this Initial EP, in terms of both initial and the sustained rates, has a low probability of being realized. Several factors that are likely to reduce rates and volumes of released oil are not included in the WCD calculation, including obst ructions or equipment in the wellbore, well bridging, and early intervention such as

containment.Table 1

. Notices to Lessees and Operators (NTLs) Pertinent to this EIA

NTL Title Summary EIA

Section

2010

- N10 Statement of

Compliance with Applicable Regulations

and Evaluation of

Information Demonstrating Adequate Spill Response and Well

Containment Resources Requires that applications for well permits certify that the operator (Shell) will comply with all applicable regulations, including the increased safety measures regulations particularly regarding subsea blowout preventers (BOP) or surface BOPs

on floatin g facilities. BOEM evaluates whether the application demonstrates the operator‘s ability to rapidly deploy containment resources in the event of a blowout or other uncontrolled discharge. 2.2.2

2010

- N06 Information

Requirements for Exploration Plans,

De velopment and Production Plans, and Development Operations Coordination

Documents on the OCS Provides guidance on calculating the worst case discharge, superseding NTL 2008

- G04. 1.5

2.2.2

4.13

2009

- G40 Deepwater Benthic

Communities Instructs operators to avoid and protect high

density deepwater benthic communities (particularly chemosynthetic and deepwater coral communities) during exploration and production in water depths greater than 984 feet (300 m). Requires a buffer of 2,000 feet (610 m) around

mud and cuttings discharge locations and 250 feet (76 m) around all other seafloor disturbances. 4.4

2008

- G04 Information

Requirements for Exploration Plans and Development Operations Coordination

Documents Provides guidance on the contents of OCS plans,

incl uding the EIA. 2.0

2007

- G04 Vessel Strike Avoidance

and Injured/Dead Protected Species Reporting Directs operators to consider training vessel crews to recognize and avoid protected species, especially marine mammals and sea turtles, and to report sighti ngs of any dead or injured protected species. 4.6.4

4.8.1.4

4.8.3.4

4.8.4.4

4.13.4.1

2007

- G03 Marine Trash and

Debris Awareness and

Elimination Directs operators to properly dispose of trash and debris that may enter the marine environment; requires informational placards on offshore vessels and structures; requires annual training in proper handling of marine trash and debris. 2.1.7

4.5

4.6.2

4.8.1.1

4.8.4.2

4.12.3

2005

- G07 Archaeological Resource

Surveys and Reports Interprets regulations on documenting and protecting archaeological discoveries, performing resource surveys, and preparing reports. 4.11.1

2009

- G06 Military Warning and

Water Test Areas Provides instructions for communication with command headquarters for military warning and

wat er test areas in the Gulf of Mexico. Lessees are required to coordinate the use of vessel and 4.12.6NTL Title Summary EIA

Section aircraft and to report electromagnetic emissions in the applicable warning area or water test area.

1.6 EIA Organization

This EIA provides all of the information requested in NTL 2008

- G04 as well as the NTLs listed in Table 1

. Section 2.0 introduces the potential impact

- producing factors associated with the proposed action.

Section 3.0 briefly describes alternatives considered in developing the proposed action. Section 4.0 describes the affected environment, largely by incorporating existing analyses prepared for the central Gulf of Mexico, and evaluates the impacts of the proposed acti on on environmental, archaeological, and socioeconomic resources; it also includes a discussion of cumulative impacts. Section 5.0 discusses environmental hazards, including geologic hazards, severe weather, and currents and waves. Mitigation

measures ar e presented in Section 6.0. Interagency consultations are documented in Section 7.0, and a

list of individuals who contributed to this EIA is in Section 8.0. Literature cited is in Section 9.0.

2.0 Potential Impact Producing Factors

The BOEM ‘s programmatic EISs evaluated an extensive list of potential OCS activities that could adversely affect resources in and near the project area (MMS 2007a, b; 2008; BOEM 2011a). The proposed plan would include only a few of the activities evaluated in the programmatic EISs. BOEM recommends that the EIA include a matrix of impact

- producing factors (IPF) and resources, outlined in NTL 2008

- G04, to streamline the analysis of potential project

- specific impacts.

Potential IPFs of the proposed action may result from both routine and accidental events. Routine IPFs associated with the proposed action may include (1) noise and lights, (2) physical disturbance of the seafloor, (3) water intake, and (4) effluent ( Table 2 ). Accidental IP Fs include (1) small fuel and chemical spills, (2) a large oil spill, and (3) vessel strikes ( Table 3 ). Onshore waste disposal and marine debris were determined not to be IPFs for the proposed action. Detailed analysis of potential a nd actual IPFs is

in Section 4.0 . A complete matrix of potential IPFs is in Appendix A.Table 2 . Potential IPFs Associated with Routine Activities under the Proposed Action

Potential Impact

- Producing Factor*

Environmental

Resources Noise/Lights (drillship and support vessels) (Section 2.1.1) Physical

Disturbance (drillship and support vessels) (Section 2.1.2) Water
Intake (drillship) (Section 2.1.3) Effluent

(drillship) (Section 2.1.4) Air

Emissions (Section 2.1.5)

Air Quality X Water Quality X

Seafloor Communities X X Lower Trophic Levels X

Fisheries X X X X

Sea Turtles X X X

Sea Birds X X X

Marine Mammals X X X

Commercial and Recreational Fishing X X

Note: Factors that may adversely affect the given resource are marked with an X and discussed in the text.

See Section 4 .0 for a complete description of the resources listed here. *Potential IPFs that were determined not to adversely affect resources under the proposed action include onshore waste disposal (Section 2.1.6) and marine debris (Section 2.1.7).

2.1 IPF S Associated with Routine Activities

Routine activities that may affect environmental resources include (1) lights and noise, (2) physical disturbance of the water column and seafloor, (3) air emissions, (4) water intake, and (5) discharge of effluent. Other potential IPFs resulting from rou tine activities that are not expected to cause any impacts include onshore waste disposal and marine debris.

2.1.1 Noise and Lights

The proposed action would introduce noise and lights to the project area associated with the drillship, support vessels, an d helicopters (MMS 2000, Thomsen and others 2011). The Noble Globetrotter

, or a similar DP drillship, would be on site for about 148 days to drill the initial exploration well, then an additional 128 days for each of the subsequent wells. Three offshore support vessels and a helicopter would make regular trips to the project site as necessary. The drillship would add noise to the environment as it uses propellers and thrusters to mobilize and hold its position; s hipboard generators and drilling machiner y would create additional noise. Drilling can generate unidirectional noise with a bandwidth between 10 and 1000 Hertz (Hz); the main energy is focused in the 30 to 60 Hz range (Thomsen and others 2011). Support vessels and helicopters would

travel to an d from the drillship daily, adding transient noise to the immediate environment as they pass by. In addition to noise, the drillship would also add nearly constant artificial light sources to the project area. Vessels and helicopters traveling at night would introduce transient light sources to the immediate area. The lights are required for safety and navigation but are considered potential IPFs for seabirds and marine animals. The impacts of noise and lights on biological resources are discussed as a ppropriate in Section 4.5 (Fish, Fisheries, and Essential Fish Habitat), 4.6 (Sea Turtles), 4.7 (Coastal and Marine Birds), and 4.8 (Marine Mammals).

2.1.2 Physical Disturbance of the Water Column and Seafloor

The drillship would be in open water in the pr oject area for a period of several months. The presence of the DP drillship would not cause any adverse effects to environmental resources. The drillship mayinadvertently function as a fish

- attracting or fish

- aggregating device (FAD), meaning that pelagi c fish,

especially tuna, may congregate near it.

The Noble Globetrotter and similar drillships use thrusters rather than anchors to maintain position while they drill a well. The only anticipated disturbance of soft bottom communities of the seafloor wo uld result from the positioning of the wellbore and the BOP. Once the wellbore is in place, mud and drill cuttings would be deposited in the immediate vicinity of the wellbore.

2.1.3 Water Intake

Seawater will be drawn from several meters below the ocean surface for various services including

firewater and once

- through, non

- contact cooling of machinery on the drilling rig. Water intakes can impinge or entrain pelagic organisms, leading to injury or mortality. Under Section 316(b) of the Clean Water Act, cooling water intakes must use the best technology available (BTA) to m inimize impingement and entrainment of organisms. EPA recently expanded the Section 316(b) regulations to include ―new,

non

- fixed‖ facilities such as the Noble Globetrotter (implemented via EPA NPDES General Permit GMG 290000). The Noble Globetrotter wil l be in full compliance with the BTA requirements specified in the NPDES permit.

2.1.4 Effluent Discharges

Shell discharges effluent offshore in compliance with EPA General Permit No. GMG 290000 under the National Pollutant Discharge Elimination System (NP DES). All effluents would be discharged as required by the permit (see Initial EP Section 7 ).

Effluents would include water

- based drilling mud and cuttings, excess cement slurry, synthetic

- based mud (SBM), water

- based blowout prevention fluid, treated bilge water, treated chemical product waste,

non

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated fire water and ballast water ( see Table 7a in Initial EP ). The potential impacts of

these effluents are discussed in Sections 4.2 (Water Quality), 4.4 (Deepwater Benthic Communities), and 4.5 (Fish, Fisheries, and Essential Fish Habitat).

Cuttings would be discharged and at the seafloor as the initial well intervals are being installed. Once the marine riser is set, cuttings would be returned to the surface. Excess cement slurry produced when the casing is being installed during the riserless portion of the operatio n would be discharged at the seafloor.

Once the riser is installed, an SBM system would be used. The SBM would be recovered for recycling at an onshore facility. SBM cuttings would be discharged overboard only when the SBM interval is being

drilled. Th ose cuttings would first be treated to reduce retention of SBM fluid to less than 6.9 percent (the maximum allowable under the NPDES permit). Discharges of cleaned SMB drill cuttings are

addressed in Initial EP Table 7a ).

2.1.5 Air Emissions

The drillship and support vessels will produce air emissions resulting from combustion of diesel fuel, as

described in Initial EP Section 8 . Air emissions from diesel combustion include suspended particulate matter (PM), sulfur oxides (SO

x ), nitrogen oxides (NO

x ), vol atile organic compounds (VOCs), and carbon monoxide (CO).

Shell prepared an Air Quality Emissions Report following BOEM guidance. Estimated emissions for the drillship are below exemption levels and are not expected to significantly affect onshore air quality for any of the criteria pollutants (30 CFR 250.303). Although no additional modeling or mitigation measures

are r equired, it is Shell‘s standard procedure to further reduce emissions by using low

- sulfur fuel. Air emissions resulting from an accidental spill are discussed in Section 2.2.2.1.6 Onshore Waste Disposal

The proposed action will generate Exploration & Pr oduction (E&P) waste ( Initial EP Section 7 ) which will be collected and disposed of at Newpark Environmental Services or U.S. Liquids of Louisiana (both in Fourchon, Louisiana). Nonhazardous trash and debris and non

- recyclable waste will be transported to the Republic/BFI landfill in Sorrento, Louisiana, or the parish landfill in Avondale, Louisiana. Nonhazardous recyclable waste, including used oil, glycol, oil filters, oily rags and pads, empty drums, and cooking oil, will be recycled at Omega Waste Man agement, West Patterson, Louisiana, or at ARC of New Iberia, New Iberia, Louisiana. Hazardous waste (paints, solvents, and unused chemicals) will be transported to Safety Kleen Systems, Inc., in Denton, Texas. Universal waste such as batteries, lamps, gl ass, and mercury

- contaminated waste will be disposed of at Lamp Environmental Industries in Hammond, Louisiana. Wastes will be recycled or disposed of in compliance with all applicable regulations. Although onshore waste disposal is a potential IPF, Shel l‘s standard procedures reduce the

IPF to non

- significant levels under the proposed action.

2.1.7 Marine Debris

Shell‘s standard operating procedures for minimizing marine debris are aligned with the International

Convention for the Prevention of Pollutio n from Ships (MARPOL 73/78) Annex V requirements, federal regulations, and BOEM ‘s NTLs on solid wastes. Operators may not purposefully discard trash or debris overboard into the marine environment (30 CFR 250.300[a] and [b] [6]). To discourage illegal d umping, federal regulations require that all equipment, tools, and containers (such as drums) be marked with permanent identification (30 CFR 250.300[c]). As required by EPA and USCG, Shell has prepared a waste management plan and posted informational pla cards on vessels. Shell instructs all personnel to cover trash bins, document trash sent ashore, and minimize solid waste in general. Shell‘s plan incorporates the guidance in NTL 2007

- G03, directing personnel to retain waste packaging and small disposab le items, providing visual reminders in prominent locations on vessels and structures, and requiring annual educational refresher courses on the importance of minimizing marine debris. Shell‘s management plan and staff training programs effectively minimi ze the potential for marine debris to be an IPF for the proposed action.

2.2 Potential IPF S Associated with Accidents

Impacts to environmental, archaeological, and socioeconomic resources were analyzed for three types of accidental events: (1) a small fu el or chemical spill (less than 1,000 bbl), (2) a large spill, and (3) vessel

strikes. These IPFs are summarized in Table 3 , introduced briefly below, and analyzed in more detail in

Section 4.0.Table 3

. Potential IPFs Associated with Accidents under the Proposed Action

Potential Impact

- Producing Factors

Resources Small Fuel or Chemical Spill Large Oil Spill Vessel Strikes (boats and helicopters)

Environmental Resources Air Quality X X

Water Quality X X Offshore Biological Resources

Seafloor Communities X Chemosynthetic Communities X Lower Trophic Levels X X

Fish, Fisheries, and Essential Fish Habitat X X

Sea Turtles X X X

Seabirds X X X

Marine Mammals X X X

Coastal Biological Resources Diamondback Terrapin X X

Shorebirds X X

Beach Mouse X X

Coastal Habitats X X Coastal Wildlife Refugia X X Archaeological Resources Shipwrecks X

Prehistoric sites X

Socioeconomic Resources Recreational Fishing X X

Non

- fishing Recreational Activities X X Coastal Employment X

Land Use X

Notes:

*See Section 4 .0 for a complete description of the resources listed here. Environmental resources that would not be adversely affected by accidental events under the proposed action include pinnacles and other sensitive topographic areas and Eastern Gulf live bottom habitats.

2.2.1 Small Fuel or Chemical Spill

Shell‘s OSRP fo cuses on (1) prevention, (2) response, and (3) cleanup, as detailed in the OSRP. This combined effort makes it exceedingly unlikely that a small fuel or chemical spill would cause any significant impact beyond a transient effect on the immediate localized area. Shell‘s approach to minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 9b

.

A small fuel spill is the most likely type of spill to result from the proposed action, based on the history of exploration and d evelopment activities in the OCS. The Multisale EIS concluded that a minor diesel spill (less than 1 bbl) is the most likely type of accident to occur during typical offshore activities (MMS 2007b), and that ―moderately‖ sized spills (up to 1,000 bbl) wou ld occur infrequently ( BOEM 2011a). Most small spills result from a ruptured hose during fuel transfer and release no more than 3 bbl of diesel into the water (MMS 2007b). Spills of less than 1,000 bbl are not expected to persist long enough to

reach the shoreline, but may cause temporary effects to offshore resources (BOEME 2011a). Impacts of a small spill are discussed in Section 4.0 for each resource.2.2.2 Large Oil Spill

An uncontrolled flow of a reservoir fluid may release gas, condensate, oil, dri lling fluids, sand, or water into the environment. ―Loss of well control‖ refers generally to both minor and serious well control incidents. A serious loss of well control with a greater risk of oil spill or human injury is called a ―blowout‖ (MMS 2007b) . Following the guidance provided in NTL 2010

- N06, Shell calculated that

271 ,000 bbl could be discharged during the first day of a blowout, with a 30

- day average of 233 ,000 BOPD under the proposed action. During the 157 days it could take to drill a relie f well, a total volume of

11.4 million barrels of oil could be discharged. Calculations supporting these estimates are in Initial

EP Section 2j . In its OSRP, Shell certified that it is prepared to respond to an oil spill greater than the

referenced WCD.

The WCD scenario for this Initial EP, in terms of both initial and the sustained rates, has a low probability of being realized. The WCD calculation is based on the co

- occurrence of multiple highly

- unlikely assumptions, and does not include any response a ctions (International Association of Oil & Gas Producers 2011). Obstructions or equipment in the wellbore, well bridging, and early intervention would reduce the actual rate of discharge and volume of a spill to less than the calculated WCD.

Shell‘s well control and blowout prevention measures, described in Initial EP Section 2j , are focused on minimizing a blowout that would cause a large spill. By definition, the WCD is an exceedingly unlikely event. Shell‘s focus on safety and precaution, coupled with its commitment to rapid response, further reduces the probability that a large spill will occur, as described in Initial EP Section 2j . Shell has aggressively developed policies and procedures to prevent blowouts, minimize the discharge resu lting from a blowout, and contain the product resulting from a discharge. Shell‘s response to NTL 2010

- N06 and compliance with NTL 2010

- N10 and the Interim Final Drilling Safety Rule are detailed in Initial EP

Sections 2j and 9b

.

Notwithstanding the rec ent DWH event, blowouts during deepwater exploratory drilling remain exceedingly rare in the Gulf of Mexico. Between 1992 and 2005, less than 10 percent of all blowouts in the Gulf of Mexico caused releases of oil, and most blowouts lasted less than 12 ho urs (MMS 2007b). More recent estimates of blowout probabilities are even lower because of increased awareness and enhanced safety equipment ( BOEM 2011b, d).

In the unlikely event that a large spill were to occur under the proposed action, oceanographic conditions at the time would influence the ultimate trajectory of the oil. A quantitative spatial Oil Spill Risk Analysis (OSRA) model incorporating winds and current data in the project area estimates conditional contact probabilities for shoreline segm ents (Ji and others 2004). The OSRA model predicts that a spill in the proposed action area (Launch Area 57; MC 525) would not result in shoreline contact during the first 10 days. After 30 days, oil could reach six Louisiana parishes, three Mississippi counties, three Alabama counties, and three Florida counties. The greatest likelihood of contact within 30 days (21 percent) is in Plaquemines Parish, Louisiana (Ji and others 2004) ( Table 4 ).Table 4

. Conditional Probabilities of Shoreline Contact

Shoreline Segment County/Parish, State Conditional Probability of Contact within 30 Days (percent) a

C13 Cameron, Louisiana 1

C14 Vermilion, Louisiana 1

C17 Terrebonne, Louisiana 2

C18 Lafourche, Louisiana 2

C20 Plaquemines, Louisiana 21

C21 St. Bernard, Louisiana 3

C22 Hancock & Harrison, Mississippi 1

C23 Jackson, Mississippi 1

C24 Mobile, Alabama 1

C25 Baldwin, Alabama 1

C26 Escambia, Alabama 1

C28 Okaloosa, Florida 1

C29 Walton, Florida 1

C30 Bay, Florida 1
Source: Ji and others (2004)

a Values are the conditional probabilities that a hypothetical spill originating in the lease area (Oil Spill Risk Analysis

Launch Area 57) could contact shoreline segments within 30 days. All probabilities within 0 and 10 days were less than 0.5 percent.

The OSRA model represents an uncontained 30

- day spill in the absence of any response action. It does not take into account the environmental fate of the oil once it is released, such as weathering and microbial degradation ( Ji and others 2004).

As demonstrated by the DWH event, the fate of oil released into the Gulf of Mexico would be greatly affected by human intervention. Shell‘s spill response, as described in the OSRP and summarized in

Initial EP Sections 2j and 9b

, would minimize the volume of a spill that would ultimately make contact with the shoreline. In the updated OSRP, Shell certified that it was capable of responding to a spill larger

than the calculated WCD for the proposed action.

Since the DWH event, Shell and other operators In the Gulf of Mexico have developed an integrated subsea well control and containment system deployed through the Marine Well Containment Company (MWCC), a non

- profit organization that coordinates and assists with responses to large spills. Shell has full access to all of the resources available through MWCC for subsea containment of an unplanned release. Through the MWCC and other resources, Shell is compl iant with all the requirements of

NTL 2010

- N10. Other resources include the Clean Caribbean & Americas (CCA), Marine Spill Response Corporation (MSRC), Clean Gulf Associates (CGA), and Oil Spill Response Limited (OSRL). As an active

member of these and o ther organizations, Shell has access to equipment and personnel needed for spill response. Shell also supports development of new technology and procedures to respond to accidental releases, based on experience with the DWH event. Because of the lessons learned during the response to that event, Shell is substantially better prepared today to respond to a large spill. Additional details on Shell‘s extensive commitment to spill containment and cleanup are in the OSRP.

The initial response to a blowout is to physically recover as much oil as possible, as described in the

Offshore On

- Water Recovery Activation List in Shell‘s OSRP. In the event that dispersants are needed, Shell has agreements in place with suppliers in the Gulf States such as MSRC in Texas, Louisiana, Mississippi, and Florida; MWCC; CGA/Airborne Support, Inc. (ASI) in Louisiana and Texas; and Clean

Caribbean and Americas in Florida. Additional supplies are available from international vendors. Under certain conditions, open

- water in situ b urning may be a suitable control strategy (USCG 2009). Shell is prepared to deploy trained burn crews if the situation warrants such a response.Separate and apart from a dedicated human response to a large oil spill, natural processes such as

weathering and biodegradation would work to reduce the volume and alter the characteristics of spilled oil. Oil begins to weather as soon as it is released to the environment, losing up to 23 percent of its volume within the first 2 hours under certain conditions ( deGouw and others 2011). The lighter aromatic and aliphatic hydrocarbons are the first constituents of oil to enter the atmosphere, where there are quickly degraded by sunlight (Operational Science Advisory Team [OSAT]

- 2 2011). Weathering involves physic al, chemical, and biological processes that alter the physical and chemical properties of the oil, reducing its toxicity to marine organisms. Physical weathering mechanisms include spreading, evaporation, dissolution, dispersion, emulsification, photochem ical oxidation, and adsorption to suspended particulates. Ultimately, weathered oil may settle to the seafloor, where it becomes integrated with bottom sediments (NRC 2003).

Microbial organisms native to the Gulf of Mexico degrade oil at the surface and in the water column by releasing the lighter aromatic portions of the oil (Atlas and Hazen 2011). Heavier components are more difficult to degrade and may persist in the environment for a longer time. Temperature, access to oxygen, and physical perturba tion of the water affect the rate at which oil is consumed by microbes. Dispersants may accelerate microbial degradation under some conditions (Atlas and Hazen 2011) but inhibit degradation under other conditions (Hamdan and Fulmer 2011). Tracer studies s howed that carbon from the oil spilled during the DWH event was quickly incorporated into the bodies of zooplankton, apparently through food chain transfer (Graham and others 2010). Evidence of the complex effects of dispersants on ecosystem processes is discussed in the WPA SEIS BOEM (2011a).

2.2.3 Vessel and Helicopter Strikes

Vessel collisions would be expected to occur infrequently during the course of the project. Most vessel collisions involve a boat and a platform or pipeline riser, which could res ult in a small fuel spill (MMS 2007b). Only eight vessel collisions associated with oil and gas operations were reported to the BOEM in the entire Gulf of Mexico in 2010 ( BOEM 2011e). However, vessels may also collide with marine

mammals or sea turtles. The impact of each of these scenarios is discussed in Section 4.0. Helicopter accidents involving drillships are extremely rare and not considered significant in this EIA. Helicopter collisions with birds are more likely but not considered to result in s ignificant impacts because of the infrequency of helicopter use in the project area and the absence of threatened and endangered avian species in the vicinity.

Shell will comply with all USCG

- and BOEM

- mandated safety requirements to minimize the potenti al for vessel collisions with structures and animals. Shell contracts directly with professional vessel operators, who are responsible for adhering to all federal regulations. As an additional level of support for the vessel operators, Shell maintains a 24

- hour communication link for vessel operators to report any

incidents.

2.3 Hydrogen Sulfide

The proposed action is in an area where hydrogen sulfide (H 2 S) concentrations have not been characterized. Based on 30 CFR 250.490 (c), Shell has requested that the area where drilling operations are proposed be classified as having ―unknown‖ presence of H 2 S.

3.0 Alternatives

No formal alternatives were evaluated in this EIA. However, Shell evaluated several alternative locations for wellsites, choices of drilling rigs and drillships, and other operational elements as part of the proposed action. The proposed action is within the range of activities evaluated as the preferred alternative in the Multisale EIS (MMS 2007b). Technical and logistical necessities precluded development of other alternatives that would accomplish the goals of this project.4.0 AFFECTED ENVIRONMENT and Impact Analysis

Water depths in the project area range from approximately 7, 45 0 to 7, 60 0 feet (2,2 70 to 2,3 16 m), according to the Geohazards Assessment report (Fugro GeoServices, Inc. 2002). The relatively flat seafloor is interspersed with hummocky a reas ( Figure 2 ). The overall gradient is less than 1° to the

east

- southeast, but gradients up to 3° occur in the area (Fugro GeoServices, Inc. 2002). The proposed

surface locations of the wellsites in MC 525 are considered suitable fo r drilling (C&C Technologies 2009).

The affected environment of the northern Gulf of Mexico was described in detail in programmatic EISs (MMS 2007a,b, 2008; BOEM 2011a) and in a SEA prepared for an exploration plan in nearby lease blocks ( BOEM 2011b), ref

erred to as SEA S

- 7445. The affected environment in MC 525 is similar to that

described in SEA S

- 7445, and the SEA is incorporated by reference. These NEPA documents reflect exhaustive reviews of the scientific literature, including recent information on impacts of the DWH event that is not yet available to the public. This section provides baseline information and impact assessment for environmental, biological, archaeological, and socioeconomic resources as well as a discussion of cumulative impacts.Figure 2 . Bathymetry and Proposed Well Surface Locations.Principal environmental resources of concern include air quality ( Section 4.1 ) and water quality ( Section

4.2 ). Biological resources addressed in this section include lower trophic level organisms, deepwater benthic communities (chemosynthetic and nonchemosynthetic), fish and fisheries, sea turtles, birds, marine mammals, and terrestrial animals, alon g with their habitats ( Sections 4.3 through 4.10 ). Archaeological and socioeconomic resources are also addressed ( Sections 4.11 and 4.12 ).

NEPA regulations allow for, and even recommend, that project

- specific EIAs be tiered from broad programmatic EISs. Baseline conditions of resources and potential impacts resulting from routine

activities an d accidental events have been extensively described in the programmatic EISs (MMS 2007b, 2008), the EA for Gulf of Mexico deepwater operations and activities (MMS 2000), and SEA S

- 7445 ( BOEM 2011b); these documents are incorporated by reference in this tiered EIA. Accordingly, description of the affected environment and potential impacts in this EIA is limited to new or site

- specific conditions. This section incorporates existing NEPA analyses and evaluates additional site

- specific impacts relevant to the proposed action.

An analysis of the significance of impacts under NEPA requires consideration of both context and intensity (40 CFR 1508.27). Context includes spatial, temporal, and ecological parameters, such as the size of the affected area, the dur ation of the effect, and the ability of the resource to recover from the effect. Intensity describes the severity of the effect. Significance can sometimes be defined quantitatively, as

when a measured concentration of a chemical in the environment is com pared with a toxicological benchmark. More often, significance is described using qualitative measures because data are not available to support quantitative analysis. A Finding of No Significant Impact (FONSI) under NEPA represents a conclusion that the e xpected impacts are below a level of significance that would warrant preparation of an EIS (40 CFR 1508.13). In the discussion below, Shell provides scientifically defensible rationale to support a FONSI for the proposed action.

4.1 Air Quality

No site

- s pecific air quality data are available for the project area, which is 79 miles (127 km) from the nearest shoreline. Attainment status under the Clean Air Act pertains only to state waters; the project site is in federal OCS waters and so is unclassified ( MMS 2007b, Matthews and Cameron 2010). All coastal parishes in Louisiana and counties in Mississippi, Alabama, and Florida are attainment areas under the National Ambient Air Quality Standards (NAAQS) for all criteria pollutants (EPA 2011a). The proposed action would occur in the open Gulf of Mexico, where air quality is expected to be good. Winds in the northern Gulf of Mexico are driven by the clockwise circulation around the Bermuda High, which creates prevailing winds toward the shore (MMS 2007b). The prevailing winds are affected by hurricanes and tropical storms during summer and fall and by extratropical cyclones (cold fronts) during winter. During a 12

- month period, winds may blow from virtually any direction (MMS 2007b). Potential

IPFs result ing from routine activities and accidental events are described below.

4.1.1 Impacts of Routine Activities on Air Quality

The projected emissions for the drillship are below exemption levels, as presented in the Air Quality Emissions Report (see Initial EP Section 8 ). Therefore, according to the definitions set forth in

30 CFR 250.303, drillship emissions will not significantly affect onshore air quality for any of the criteria pollutants. No further modeling, analysis, or control measures are required. Shell‘s standard policy is to

use low

- sulfur fuel to minimize impacts from fuel combustion.

The drillship, support vessels, and helicopters will produce air emissions typical of combustion of diesel fuel in generators, pumps, and motors. Routine activities will contribute primary air pollutants such as suspended PM, SO

x , NO

x , VOCs, and CO. Offshore emissions of this sort are not considered to adversely

affect air quality onshore because of the temporary nature of the activity and the distance of the projectarea from shore. P revailing atmospheric conditions, emission heights, and emission rates further limit the

impacts to air quality (MMS 2007b).

The BOEM coordinates with the National Park Service (NPS) when offshore operations produce any

po tential emissions within 186 miles (300 km) of the Breton Wilderness Area, which is designated as a Prevention of Significant Deterioration (PSD) Class I air quality area under the Clean Air Act (NPS 2010). The lease area is approximately 105 miles (169 km ) from the Breton Class I area. Emissions associated with the proposed action are low, and Shell does not anticipate any impacts to air quality in the Class I area. Shell will comply with any emissions requirements. Routine activities associated with the proposed action would not cause violations of any NAAQS or significantly affect air quality.

4.1.2 Impacts of Small Fuel or Chemical Spill on Air Quality

Small spills of fuel or chemicals would have only minor, temporary impacts on air quality under the

p roposed action, comparable to those described in recent EISs (MMS 2007b, 2008; BOEM 2011a; NOAA 2006). Shell‘s standard procedures and personnel training are focused on minimizing the incidence of small spills during routine operations such as fuel transf er. If a small spill were to occur, Shell‘s OSRP would be implemented to contain and clean up the spill so that impacts would be minor and transitory ( Initial EP Sections 2j and 9b ). No significant impacts to air quality would result because the proposed action is far from shore in the open Gulf and a small spill would be cleaned up quickly.

4.1.3 Impacts of a Large Oil Spill on Air Quality

Impacts of a large oil spill were analyzed in regional Multisale EISs (MMS 2007b, 2008; BOEM 2011b) and

the SEA S

- 74 45 ( BOEM 2011b). A large spill would cause short

- term localized impacts to air quality as VOCs evaporated from the slick. Weather conditions at the time of the release would control the immediate behavior of the slick, with greater volatilization occurri ng during warmer weather. Data from the DWH event suggest that most of the methane released during a spill would remain in the water rather than enter the atmosphere (Yvon

- Lewis and others 2011). Shell‘s OSRP describes the type of

containment that would occur to minimize impacts of a large spill. Under certain conditions, the incident commander may determine that in situ burning is the most appropriate response. Typically, in situ burning generates a visible plume of black smoke and additional emissions of NOx, SOx, CO, PM, and greenhouse gases (USCG 2009).

Most air quality impacts would typically be limited to offshore areas because the proposed action is

79 miles (127 km) from the nearest shoreline. If the spill were not contained quickly, oil could move toward the coast and temporarily affect onshore air quality, especially in Plaquemines Parish ( Table 4 ). Plumes of concentrated organic aerosols were detected over the Gulf of Mexico downwind from the DWH surface slick as the more volatile constituents were volatilized (deGouw and others 2011; Coe 2011). Any air quality impacts would be transitory, based o n data collected following the DWH event. EPA‘s air quality monitoring data indicate that the DWH spill and associated in situ burning did not result in any long

- term impacts to air quality (EPA 2011b). Based on the WCD calculation, a large oil spill unde r the proposed action would not exceed the volume of the DWH spill. The proposed action would not cause any long

- term significant impacts to air quality. No long

- term reduction in air quality resulting from the proposed action would affect either humans o r wildlife.

A large oil spill is an extremely rare event, made even more unlikely by the enhanced prevention and containment protocols developed since the DWH event (described in Initial EP Section 2j and Shell‘s OSRP). Were a large spill to occur, She ll would immediately implement its OSRP to mitigate and reduce the potential impacts. No significant long

- term impacts to air quality, measured as concentrations of contaminants exceeding NAAQSs, are expected to result from a large spill because of Shell‘ s rigorous measures to prevent a spill and the expanded capability through the MWCC to respond to an unplanned

release.4.2 Water Quality

Deep waters of the northern Gulf of Mexico are characterized by relatively uniform temperature, salinity, and oxygen, and very low levels of contaminants (Kennicutt 2000). The lease area where the proposed action would occur has no unique water quality features and is expected to conform to the descriptions in the Multisale and Supplemental EISs (MMS 2007b, 2008). The e ntire northern Gulf of Mexico, especially off the coast of Louisiana, is known to contain areas where oil, gas, and brine naturally seep into sediments and enter the water column. Oil enters the Gulf of Mexico from these natural seeps as well as

from the Mississippi River (NRC 2003).

Water quality at the lease site may have been temporarily affected by the DWH event. The proposed project area is only 52 miles (83 km) southeast of the Macondo well site, within the area that was covered by the surface sli ck in May 2010 (ESRI 2010). Subsequent weathering of oil and mixing of Gulf waters is expected to have eliminated any residual effects on water quality at the lease site. According to analyses conducted by OSAT, polycyclic aromatic hydrocarbons (PAH) con centrations in water and sediment samples collected beyond a 1.8

- mile (3

- km) radius of the Macondo wellsite had dropped below the chronic toxicological benchmarks by August 2010 (OSAT 2010). Weathering and dispersion of

residual oil since that time would have further reduced the concentrations of PAHs in overlying water. Available data indicate that water quality in the proposed project area has recovered from any transient

effects of the DWH event.

The IPFs potentially affecting water quality include N PDES

- permitted effluent discharges, an accidental small fuel or chemical spill, and a large oil spill.

4.2.1 Impacts of Routine Activities on Offshore Water Quality

The proposed action will comply with all limitations and regulations in NPDES general permi t GMG 290000. Permitted discharges would have only temporary, localized impacts on offshore water quality, and no impact on coastal water quality. Permitted discharges include treated SBM cuttings, sanitary and domestic wastes, deck drainage, desalinatio n unit brine and uncontaminated cooling water, fire water, and ballast water (outlined in Initial EP Table 7a ).

Discharge of treated SBM would temporarily increase turbidity in the immediate vicinity of the drillship and up to several kilometers from the discharge point (NRC 1983, Neff 1987; Netto 2009, 2010). Apart from the transient increase in suspended solids, no other impacts to water quality are expected. The small amount of SBM retained on discharged cuttings remains bound to the cuttings as t he cuttings sink to the seafloor (Neff and others 2000). Discharge of treated SBM would not result in long

- term significant impacts to offshore water quality; the proposed action would not cause water quality in the project area to exceed any toxicologica l benchmarks for marine life. Minor and temporary impacts to water quality immediately surrounding the project area would result from the permitted discharge of treated sanitary and domestic wastes from the drillship and support vessels. Discharges from s upport vessels are permitted by EPA under the NPDES Vessel General Permit (VGP) (EPA 2009).

Deck drainage would not result in any decrease in water quality beyond the immediate vicinity of the drillship. The VGP requires collection and treatment of rain water that falls on the drillship deck and other areas where it may be exposed to contaminants (such as chemical storage area). Rain that falls on clean areas of the drillship does not require treatment. Effluents generated by deck washings and runoff fr om curbs, gutters, and drains would be treated before discharge.

The VGP does not require treatment of desalination unit brine and uncontaminated cooling water, fire water, or ballast water because these non

- toxic effluents would be rapidly diluted and not result in any impacts to offshore water quality. In summary, routine, permitted discharges would not cause anysignificant adverse effects to water quality; no toxicological benchmarks for marine life would be

exceeded.

4.2.2 Impacts of a Small Fuel or Chemical Spill on Offshore Water Quality

As outlined in Section 2.2.1 , a small fuel or chemical spill is extremely unlikely to cause any significant impact to offshore water quality beyond a transient effect on the immedi ate localized area. Shell‘s approach to minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section

9b

.

Shell‘s OSRP includes protocols for containing and cleaning up small fuel or chemical spills. The specific procedur es would vary depending on the product spilled, location (nearshore/offshore), sea state, weather, and other immediate conditions. Regardless of the particular cleanup methods, a small spill (3 bbl) would be quickly contained and recovered, causing no lon g

- term impact on environmental resources. Diesel spills are particularly short

- lived because diesel floats on the sea surface, where its low molecular

weight constituents readily volatilize (NRC 2003; NOAA 2006). Higher weight constituents that remain in the waters undergo microbial degradation and oxidation, resulting in short chain carbon compounds. If the spill occurs near shore, some of the diesel may enter coastal vegetated habitats for a brief time. However, microbial degradation would occur in th e vegetated areas as well, and impacts would be transient (NOAA 2006). It is expected that small fuel spills will occur predominantly in the open Gulf of Mexico where no significant impacts to water quality would result because most fuel transfers occur a t the drillship rather than near shore. The spill would not impair the ability of offshore waters to support marine life. Even if a small spill reached the shore, impacts to fishes would be transient and reversible. A spill of 600 bbl of crude oil in Bara taria Bay, Louisiana had no long

- term effects on species composition or community structure of fishes; both of these metrics had returned to baseline condition within one year of the spill (Roth and Baltz 2009).

The MC Block 525 lease area is 79 miles (1 27 km) from the nearest shoreline ( Figure 1 ). Spill trajectory modeling predicts that a large spill in the project area would not reach the shoreline within 10 days of a spill ( Table 4 ). A small diesel spill would be fully volatilized or degraded within 10 days, reducing the risk of shoreline contact to zero (NOAA 2006). Even larger fuel spills (up to 1,000 bbl) are not expected to remain visible on the surface of the water long enough to cause significant im pacts to coastal lands (MMS 2007b). Quantitative spatial modeling that incorporates degradation and breakdown of the fuel as well as actual paths of historical spills concluded that coastal habitats are not at substantial risk of oiling by spills smaller than 1,000 bbl (MMS 2007b).

Although it is possible that other chemicals would be spilled, the probabilities are exceedingly small. MMS evaluated small spills of fuel and other chemicals and concluded that chemical spills are not likely to cause signific ant impacts to environmental resources in the OCS (MMS 2008; BOEM 2011a); no toxicological benchmarks would be exceeded. More than 20 chemicals typically used in deepwater OCS activities were evaluated for toxicity to marine organisms. Most of the chemica ls posed no risk to environmental resources in the volumes used in deepwater projects. Only zinc bromide and ammonium chloride could cause impacts to marine resources (Boehm and others 2001). Neither zinc bromide nor

ammonium chloride would be used in th e proposed action. Small fuel or oil spills would have no significant impact on water quality.

4.2.3 Impacts of a Large Oil Spill on Offshore Water Quality

A blowout resulting in a large oil spill is an exceedingly unlikely event, as described in Section 2.2.2 and in the Multisale EISs (MMS 2007b, 2008; BOEM 2011a). Shell has certified in its OSRP that it is prepared to respond to a spill substantially larger than any spill that could result from the proposed action (see

S hell‘s OSRP). Following the guidance provided in NTL 2010

- N06, Shell calculated that 271 ,000 bbl could be discharged during the first day, with a 30

- day average of 233 ,000 BOPD. During the 157 days it would take to drill a relief well, a total volume of 1 1.4 million barrels of oil could be discharged. Calculations supporting these volumes are in Initial EP Section 2j

.In the unlikely event that a large spill were to occur under the proposed action, oceanographic conditions

at the time would influence the ultimate fate and path the oil would take. Results of the OSRA model are

described in Section 2.2.2 and Table 4 . Potential impacts of a large spill were evaluated in the Multisale and Supplemental E ISs (MMS 2007b, 2008; BOEM 2011a). A large spill would produce an initial slick on the water surface, which would immediately begin to disperse and weather. Once oil is released from the well, it mixes with seawater and separates into fractions that have different physical and chemical characteristics that influence how they behave. Storms or other disturbances increase the rate of dispersion of the surface slick and enhance the dissolution of the low

molecular

‐ weight aliphatic and aromatic hydrocarbons into the water column (OSAT

- 2 2011, NRC 2003). The volume of spilled crude oil decreases within a few days of a spill. Only 25 percent of the original volume of spilled light crude oil would remain after a few days (up to 60 percent of a medium crude oil spill) as the lower molecular weight benzene, toluene, ethyl benzene, and xylenes are lost (OSAT

- 2 2011.)

When subsea dispersants are applied to the oil during a release, the oil may move laterally beneath the surface of the water rather than rising to the surface as expected (Camilli and others 2010, Hazen and others 2010, Joint Analysis Group 2010a, b, c). The dispersants themselves may affect offshore water quality for some time after the spill. After the DWH event, oil and dispersants were detecte d at 3,280 to 3,937 feet (1,000 to 1,200 m) as far as 186 miles (300 km) from the wellsite (Kujawinski and others 2011). Over time, water quality would return to pre

- spill conditions as the remaining oil and dispersant were degraded and diluted by Gulf wa ters (MMS 2007b; BOEM 2011a). A large oil spill may include a release of gaseous hydrocarbons that could temporarily impair offshore water quality. The proposed action is in an area where the concentration of H 2 S is unknown. The release and subsequent m etabolization of methane could cause a short

- term minor decrease in dissolved oxygen concentrations in the area. Transient depressions in dissolved oxygen concentrations may follow an oil spill as microbes degrade the oil, but no long

- term hypoxia (define d as less than 2.0 milligrams [mg] per liter [L]) is expected to occur (Joye and others 2011, Kessler and others 2011, OSAT 2010). Depressed dissolved oxygen concentrations near the Macondo wellhead had returned to pre

- spill levels by October 2010, 6 mont hs after the release (OSAT 2010).

The lease area is 79 miles (127 km) from the nearest shoreline, reducing the likelihood that coastal water quality impacts would result from a large oil spill. The OSRA model predicts that the most likely

nearshore water quality impacts would occur near Plaquemines Parish, Louisiana ( Table 4 ). Shell‘s OSRP focuses on rapid containment of a spill so that coastal waters would not be affected, as described in

Initial EP Section 2j and 9b . The combined effort of prevention, containment, and rapid cleanup detailed in Shell‘s OSRP make it extremely unlikely that a large spill would cause any long

- term significant impacts to water quality.

4.3 Lower Trophic Level Organisms

By far the most abundant organisms in the open waters of the Gulf of Mexico are phytoplankton and zooplankton . The plankton co mmunity consists of both permanent members and transient larval forms of fishes and invertebrates (Johnson and Allen 2005). Plankton and marine invertebrates in the open waters of the Gulf of Mexico are the basis of the food web that supports fish, birds, sea turtles, and marine mammals and provides recreation and economic benefits to people. The composition of the planktonic community in any given location and depth changes over time in response to physical factors such as wind, currents, turbidity, nutri ent availability, and light (Hernandez and others 2010). Ecological processes such as predation and competition also influence the abundance and distribution of various species. Lower trophic level communities are characterized by mixed species assemblages of phytoplankton, zooplankton, and ichthyoplankton, as well as benthic and pelagic invertebrates. These organisms are predominately moved passively within water masses, although some have limited swimming abilities.The tiny size, wide distribution, and overall abundance of most lower trophic level organisms in the open

Gulf of Mexico affords these species protection from small, localized impacts. None of the routine IPFs would cause population

- level effects. Entrainment of plankton life forms by large capacity water intakes has historically been a concern; however, modern intake structures are designed to allow mobile plankton to escape and to limit the entrainment of smaller life forms. The Noble Globetrotter is a new drillship that

would meet the BTA requirements of minimizing entrainment and impingement to reduce impacts to non

significant levels.

The only accidental IPF that could potentially affect lower trophic levels is a large oil spill, which could cause direct mortality by smothering the orga nisms. However, lower trophic organisms tend to be ubiquitous across the well

- mixed waters of the northern Gulf of Mexico, carried long distances by the Loop currents. Even a large spill would not have population

- level impacts on any species of lower tro phic level organism.

4.4 Deepwater benthic communities

Benthic habitats in the northern Gulf of Mexico support both chemosynthetic and nonchemosynthetic

communities. NTL 2009

- G40 requires a description of features or areas that could support high

- densit y chemosynthetic communities, deepwater corals, or other associated high

- density hard

- bottom communities in waters deeper than 984 feet (300 m) so that these sensitive biological communities can

be avoided.

Chemosynthetic Communities

Oil, gas, and brine s eeps cover a substantial portion of the Gulf of Mexico, especially on the continental margin, and chemosynthetic communities have been discovered in Gulf waters as deep as 10,825 feet (3,300 m) (Fisher and others 2007). More seeps have been discovered in the Gulf of Mexico than in all other oceans combined; however, less than 1 percent of the deepwater Gulf of Mexico is believed to support high

- density benthic communities ( BOEM 2011c). The Gulf of Mexico also supports deepwater

coral communities that beco me established on the carbonate substrates created by chemosynthetic communities (MacDonald 2001; Brooke and Schroeder 2007, Cordes and others 2008). Seismic studies show that hard bottom areas occur where authigenic carbonates were generated by the seepag e process, mostly along the margins of intraslope basins (Fisher and others 2007; Brooks and others 2009). Surveys did not document any features that could support high

- density deepwater chemosynthetic communities within 2,000 feet (610 m) of the proposed wellsites (C&C Technologies 2009). The list of known high density deepwater benthic communities provided as a reference to NTL 2009

- G40 does not include any locations as far east as the proposed project area (longitude

- 87.96) or any communities

within MC 525. Nor is MC 525 mentioned in recent summaries of important deepwater benthic related communities in the northern Gulf of Mexico (Fisher and others 2007; Cordes and others 2008, 2009; Brooks and others 2009).

As described in Initial EP Section 6a , t he proposed well locations are in water ranging from 7,4 5 0 to 7,600 feet (2,2 70 to 2,316 m). MC 525 is in the extreme northern section of deepwater Grid 17, where remotely operated vehicle (ROV) coverage of the seafloor is considered inadequate to characte rize the area ( BOEM 2011f). Based on general surveys of the MC area, the seafloor is expected to be predominately softbottom (Rowe and Kennicutt 2009).

Nonchemosynthetic Communities

The Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology study provides site

- specific data on benthic habitats, communities, and species at more than 40 sampling locations (Wei 2006, Roweand Kennicutt, 2009). One sample location (S37) l ocated in the vicinity of the proposed well site in a

comparable water depth 7831 feet (2,387 m) is considered representative of the project area. Sediment at Station S37 was more than 80 percent silt and clay; the remainder was sand. The benthic communit y was typical of a softbottom basin. No hardbottom substrate was reported at this location (Rowe and Kennicutt 2009).

In general, benthic marine softbottom communities are described in terms of the mean size of organisms, defined by the type of sampling gear used to collect them. The smallest organisms are the microbiota, including bacteria, protists, and benthic foraminiferans. Many of the bacteria are capable of consuming hydrocarbons (Atlas and Hazen 2011). Bacteria and other microbiota form the bas is of the marine food web in the lease area and also function in cycling organic carbon (Rowe and Kennicutt 2009) (see Section

2.2.2 ).

The meiofauna are defined as organisms retained by a 63

- micron (0.063

- millimeter [mm]) sieve. The density of meiofauna at Station S37 was 219,179 individuals per square meter (m 2 ) of sediment. Most of the biomass was composed of nematodes (soft worms similar to pinworms), as is typical throughout the Gulf of Mexico. Macrofauna, organisms that are retained by a 300

- micron (0.3

- mm) sieve, were dominated by polychaetes (bristly marine worms) at Station S37, consistent with most softbottom deepwater marine habitats. Other macrofauna at Station S37 included amphipods, tanaids, bivalves, and

i sopods. Megafauna are organisms visible to the unaided eye, at least 100 mm wide. At Station S37, small sponges (Family Ancorinidae) and the orange brittle star ( Ophiocrates heros ) were dominant components of the megafauna (Wei 2006, Rowe and Kennicutt 2 009).

Surveys of the northern Gulf of Mexico demonstrated that benthic organisms occur in four depth

dependent faunal zones (1 through 4, shallow to deep). The proposed project area is in Zone 3E, which

consists of stations in the west flank of the low er Mississippi Fan, the lower Mississippi Canyon, the lower De Soto Canyon (S37), the lower West Florida Terrace, the deep Mississippi Fan, and one station at the base of the Sigsbee Escarpment ranging in depth from 7,200 to 10,800 feet (2,200 to 3,300 m). Dominant macrofauna of faunal Zone 3E included the polychaetes ( Paraonella monilaris and Tharyx

marioni ), two bivalves ( Heterodonta spp.), and an isopod ( Macrostylis sp.) (Wei 2006).

Deepwater corals (also called coldwater corals) occur in the Gulf of Me xico, although not in the lease area. Most deepwater corals do not form reefs like those in tropical waters. Instead, they form patches of corals, especially Lophelia pertusa , that create habitat for other organisms (Brooke and Schroeder 2007). Deepwater r eefs support biologically rich and diverse communities of crustaceans, mollusks, echinoderms, polychaete worms, sponges, and other larger animals. Deepwater corals also provide crucial habitat and reproductive grounds for commercially important fisheries. The only IPF that could adversely affect deepwater corals is a large oil spill because of the distance of the project area from these

communities.

Routine IPFs potentially affecting benthic communities include activities resulting in effluent discharges of drilling mud and cuttings and a large oil spill. A small fuel or chemical spill is not considered an IPF because the spill would not contact bent hic communities more than 7,546 feet (2,300 m) below the sea surface (see Section 2.2.1 ). The drillship itself is not considered an IPF because it does not require anchors and will not contact the seafloor except at the loc ation of the wellbore, which is described in

Section 2.1.2

.

4.4.1 Impacts of Routine Activities on Deepwater Benthic Communities

Routine activities associated with the proposed action would have no impact on chemos ynthetic communities or deepwater coral because the project area is not in proximity to any such communities ( Initial EP Section 7). Potential effects on common nonchemosynthetic communities are discussed

below.Drillships such as the Noble Globetrotter do not use anchors for holding or stabilization during drilling

operations. Positioning of the wellbore and BOP will cause minimal disturbance to benthic softbottom communities in the immediate area where the wellbore penetrates the substrate, where mud a nd drill cuttings will be deposited. During installation of the initial well intervals before the marine riser is set, cuttings and seawater

- based ―spud mud‖ will be discharged to the seafloor. Some excess cement slurry

will be released at the seafloor w hen casings are installed on the riserless portion of the well. The chemical constituents of cement slurry are not considered particularly toxic to marine life (Boehm and others 2001); however, the cement and mud can physically smother or bury benthic org anisms within tens of meters around the wellbore (Neff and others 2005; Hughes and others 2010). The disturbed area of softbottom sediments would be recolonized by larvae recruited from the overlying water or adjacent areas, but recovery may take several years (Hughes and others 2010). Species composition may shift during the recovery period as more species more tolerant of residual hydrocarbons return first, followed by other species only after the sediment returns to pre

- drilling conditions (Netto and o thers 2010).

In addition to cement slurries and mud, treated SBM cuttings discharged from the drillship and may adversely affect softbottom communities near the wellbore. Although the cuttings may physically harm benthic organisms, they do not general ly pose a risk of toxicity (Rowe and Kennicutt 2009; Netto and others 2009). Sediments in areas of particularly dense drilling activity, such as the Mississippi Canyon, may contain elevated concentrations of barium compared with background sediments; howe ver, even the highest concentrations measured around drilling sites were found not to be toxic to marine organisms (Rowe and Kennicutt 2009). The treated SBM cuttings do not persist indefinitely in the environment, but instead are gradually integrated int o the benthic habitat as the base synthetic fluid is transformed to its elemental components by microbes (Hughes and others 2010). Once drilling stops, larval recruitment from the overlying water and adjacent seafloor will return the area to its pre

- drilli ng condition (Netto and others 2009).

The spatial footprint of drilling discharges is typically considered to be limited to a radius of about 1,640 feet (500 m) around each wellsite. The affected footprint would be 970 acres (393 hectares).

Routine acti vities associated with the proposed action would not significantly affect softbottom benthic communities in the vicinity because no rare or unique softbottom communities occur within MC 525 (Wei 2006, Rowe and Kennicutt 2009). The minor impact to a limite d number of individuals is not considered to threaten the long

- term sustainability or productivity of native softbottom benthic communities. This conclusion is consistent with the analyses developed in the regional Multisale and Supplemental EISs (MMS 200 7b, 2008; BOEM 2011a).

4.4.2 Impacts of a Large Oil Spill on Deepwater Benthic Communities

A blowout would resuspend and disperse sediments within a 984

- foot (300

- m) radius of the well site and

have a direct adverse effect on benthic communities within th at area (MMS 2007b). Although larger

grained sediments (sands) would probably settle quickly within 1,312 feet (400 m) of the blowout site, finer silts and clays could remain in the water column for weeks and would be transported kilometers

from their ori ginal location. A large volume of suspended sediment would likely result from a blowout because the project area substrate is more than 80 percent silts and clays (Rowe and Kennicutt 2009). No chemosynthetic, deepwater coral, or other high

- density hardbo ttom communities occur near the well sites. The direct physical blowout event would not have any direct impact on high

- density benthic

communities.

Before the DWH event, deepwater benthic communities in Gulf waters were thought to be relatively
protecte d from large oil spills because oil naturally rises to the sea surface (MMS 2007a, 2008). However, it was demonstrated during the DWH response that application of subsea dispersants changed the fate and transport of the oil (Joint Analysis Group 2010c). Subsurface plumes in water more than 3,600 feet (1,100 m) deep were observed more than 20 miles (32 km) from the point of release about a month after the event (Camilli and others 2010). About 8 miles (13 km) from the DWH wellhead, a well

defined plume of oil between 3,280 and 13,123 feet (1,000 and 1,400 m) deep contained concentrationsof PAHs toxic to marine life (Diercks and others 2010). Others reported that chemical components of

subsea dispersants applied during the DWH event were detected up to 186 miles (300 km) from the wellsite in water below 3,280 to 3,937 feet (1,000 to 1,200 m) more than 2 months after the spill (Kujawinski and others 2011).

EPA permitted the use of subsea dispersants because the concentrations were believed to pose little risk to marine organisms. However, data on the use of subsea dispersants are limited, and it cannot be determined at this time whether dispersants would be permitted as part of the response to a blowout under the proposed action. This analysis assumed th at dispersants could be used, and that benthic communities could be exposed to a subsurface plume of oil beyond the 984

- foot (300

- m) radius affected by the physical blowout (MMS 2007a, 2008).

The impact of a large oil spill on benthic communities is con sidered temporary and not significant because no unique or rare high

- density benthic communities occur within the vicinity of the proposed action. Available data indicate that the affected area would be recolonized by common benthic organisms over a perio d of months to years (NRC 2003; BOEM 2011a; Netto and others 2009, 2010).

Chemosynthetic Communities

A large oil spill has the potential to affect chemosynthetic communities some distance from the blowout site, as described above. Although chemosynthetic organisms can tolerate, and may even require, certain concentrations of hydrocarbons, it does not follow that they can withstand concentrations above their biological threshold. Natural seeps vary in both chemical constituents and flow rate, and a

chemos ynthetic community may be tightly coupled to the particular conditions that prevail at its seep. The chemosynthetic community goes through successional stages as the flux of hydrocarbons begins, peaks, and then declines over time. A sudden plume of free product in the water column in no way represents a natural occurrence for a chemosynthetic community.

Chemosynthetic organisms grow slowly, and have limited ability to avoid or recover from exposure to oil in the water column. Impacts of a large spill to chemosynthetic communities include mortality, but also effects such as reduced growth, tissue damage, and impaired reproduction ( BOEM 2011b). Loss or injury of the chemosynthetic host organisms can cause a cascade of impacts to other organisms associat ed with the seep. Mobile organisms such as large crabs and echinoderms may be physiologically less able to tolerate elevated concentrations of hydrocarbons ( BOEM 2011b).

Severely damaged seep habitats could be recolonized by planktonic tubeworm larvae r ecruited from as far as 350 miles (560 km) away (Cordes and others 2007; 2009). Some communities undergo a phase shift to a different type of community once the area becomes suitable for recolonization because the seeps themselves do not persist indefinit ely (Fisher and others 2007). If oil or dispersants were to contact chemosynthetic communities, adverse effects such as reduced growth, impaired reproduction, or mortality could occur (Hamdan and Fulmer 2011; BOEM 2011a). The long

- term impact on chemosynt hetic communities from a large oil spill is difficult to predict because large spills are so rare and chemosynthetic communities are so sparsely distributed and diverse.Nonchemosynthetic Communities

Data from the DWH event demonstrated the potential for a large oil spill to adversely affect nonchemosynthetic communities, particularly deepwater corals ( BOEM 2010a). At a deepwater coral site 4,600 ft (1,400 m) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead, government and academi c researchers observed large populations of injured and dead corals that were sloughing tissue and other soft and stony corals covered by a brown substance. Although circumstantial evidence points to the DWH event as the causative agent of the injured cor als, laboratory analyses have not yet confirmed the identity of the brown substance.

Oil spills can impair deepwater corals by degrading hardbottom habitat, altering the assemblage of species in an area, and reducing live coral coverage. Any disturbance of coral can lead to secondary losses of associated species because deepwater coral communities provide complex biogenic structure that supports a range of other species. Effects on deepwater corals could impair their ability to recover

from other distur bances, including increases in sea temperature, acidification, and coral diseases (MMS 2007b, BOEM 2011a).

Chemosynthetic communities, deepwater corals, and other live hardbottom communities could be adversely affected by a large oil spill under the propo sed action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial

EP Section 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize

t he impacts by quickly containing and recovering the oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant spill impacts on deepwater benthic communities are expected.

Other Sensitive Benthic Areas

I n the Gulf of Mexico Large Marine Ecosystem, a zone of tuft coral provides hardbottom habitat in water 1,640 ft (500 m) deep (Reed and others 2006). The west Florida shelf is a broad carbonate platform extending from DeSoto Canyon in the north to the weste rn Straits of Florida, an area of about 30,115 mi 2
(78,000 km2). At the edge of the Florida Platform, reef and limestone outcrops provide deepwater hardbottom habitat (Hourigan 2009). Deepwater banks and associated hardbottom communities occur in

the weste rn and central Gulf of Mexico (Hourigan 2009). Tuft coral thickets occur on Viosca Knoll off the coast of Alabama and in DeSoto and Green Canyons (Reed and others 2006). In the Gulf of Mexico, between the Mississippi Canyon and the DeSoto Canyon, are two b ands of carbonate mounds called the Pinnacle Trend, which offer substantial live hardbottom habitat in an otherwise softbottom area (MMS 2007b).

The proposed project area is not within or near any designated topographic feature or a no

- activity zone

as i dentified in NTL 2009

- G39. The nearest topographic feature is Sackett Bank in the West Delta South area (Blocks 147

- 148). The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by NTL 2009

- G39, the nearest pinnacle tre nd blocks are in the Viosca Knolls area north of the project area. 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 328 feet (100 m) or less.

Neither routine activities nor accidents would adversely affect designated topographic features, pinnacles,

or other live bottoms because of the distance of these features from the lease area. A small fuel or chemical spill would float or dissipate quickly befor e it could reach these areas of topographic relief (NOAA 2006). A large oil spill could be transported up onto the continental shelf where these features occur, but this event is considered unlikely (Nowlin and others 2001).4.5 Fish, Fisheries, and Esse ntial Fish Habitat

Potential impacts of oil and gas activities on fish, fisheries, and essential fish habitat (EFH) were analyzed in the Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a) and the site

- specific SEA S

7445 for leases near the proj ect area ( BOEM 2011b); the background information and analyses in those documents are incorporated by reference into this EIA. The proposed action does not include any unique or unusual IPFs that would warrant a separate analysis, and no significant impac t on fish, fisheries, or EFH is expected to result from routine activities or small fuel or chemical spills. Shell would comply with

NTL 2007

- G03 to minimize the potential for marine debris

- related impacts on fishes. Implementation of

Shell‘s OSRP would reduce the impact of small fuel or chemical spills to fishes to insignificant levels.

Additional analysis of potential impact of a large oil spill on fish, fisheries, and EFH is presented for the Gulf sturgeon and its critical habitat, which are protecte d under the ESA ( Section 4.5.2 ); other fishes and

EFH are discussed in Section 4.5.3

.

4.5.1 Gulf Sturgeon

The federally threatened Gulf sturgeon ( Acipenser oxyrinchus desotoi ) inhabits major rivers and coastal waters from the Mississippi River east to the Suwannee River, Florida. A description of the species is given in the Multisale EIS (MMS 2007b) and summarized briefly here. The Gulf sturgeon lives up to 42 years and is a slowly maturing species. Females reach maturity at 8 to 17 years and males at 7 to 21 years (FWS and NMFS 2009; NMFS 2010a). The Gulf sturgeon is anadromous, spawning in freshwater rivers and feeding in estuarine and marine waters of the Gulf of Mexico (FWS and Gulf States Marine Fisheries Commission 1995).

Once the Gulf sturgeon leaves the freshwater habitat, it typically inhabits estuaries and nearshore bays in water less than 35 feet (10 m) deep (Ross and others 2009). Barrier island inlets provide important winter foraging grounds where Gulf sturgeon originating from different rivers congregate (Sulak and others 2009). During much of the winter, juvenile Gulf sturgeon exhibit a preference for estuaries less than 7 feet (2 m) deep, venturing into de eper offshore waters only for short periods during cold weather (Sulak and others 2009). The adult Gulf sturgeon prefers high sand content and clean sand substrata (Fox and others 2000; Harris and others 2005; Ross and others 2009).

Distribution of the Gulf sturgeon in the marine environment is likely influenced by availability of preferred prey (Ross and others 2009). Feeding habits vary by life stage, but in general the Gulf sturgeon is an opportunistic feeder in estuarine and marine habitats, taking a wide variety of benthic invertebrates such as amphipods, polychaetes, gastropods, shrimp, crabs, isopods, mollusks, and crustaceans (FWS and Gulf States Marine Fisheries Commission 1995; FWS and NMFS 2009). In the Mississippi Sound area, the Gulf
sturge on was reported to take sand dollars and annelids as well (Ross and others 2009).

In a 5

- year review published in 2009, the NMFS and FWS considered the status of the Gulf sturgeon as stable, indicating that 26 to 50 percent of recovery objectives had been achieved (FWS and NMFS 2009).

4.5.2 Impacts of a Large Oil Spill on Gulf Sturgeon

The potential for a large oil spill to adversely affect the Gulf sturgeon was analyzed in the Multisale and Supplemental EISs (MMS 2007b, 2008), by the NMFS in its Biologica l Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico (NMFS 2007), and

in the site

- specific SEA S

- 7445 for a nearby lease ( BOEM 2011b). The proposed action would be

consistent with the acti ons evaluated in those documents, which are incorporated by reference.

The nearest Gulf sturgeon critical habitat to the lease area is about 121 miles (195 km). Spilled oil would not contact Gulf sturgeon critical habitat within 30 days, based on OSRA m odeling ( Table 4 ). If spilled oil reached an area where sturgeon occurred, a sturgeon could be exposed to oil through direct ingestion of water, sediment, or prey; and by absorption of dissolved petroleum products through thegills. Subadult and adult Gulf sturgeon feeding in coastal waters would be most vulnerable to a marine

oil spill from September through April (FWS and NMFS 2009). During the rest of the year, they are in upriver areas beyond the reach of an offshore oil spill.

4.5.3 Impacts of Routine Activities on Fishes

Fish resources in the northern Gulf of Mexico range from tiny ichthyoplankton to the 18

- meter

- long whale shark ( Rhincodon typus ) (McEachran and Fechhelm 1998). Although the coastal waters of the Central

Gulf of Mexico are species

- rich, both diversity and abundance of fishes drops off as water depth increases. Between 4,921 feet and 9,842 feet (1,500 m and 3,000 m), only 32 benthic or demersal species in nine families were collected during an intensive trawl s urvey (Rowe and Kennicutt 2009). Fishes are expected to be relatively scarce in the cold deep waters of the project area, dominated by various species of eels (McEachran and Fechhelm 1998).

Highly migratory pelagic species such as tuna and billfishes m ay transit through the surface waters near the project site, but are not considered residents of the area. The most abundant component of the fish community in open waters near the drillship would be ichthyoplankton, composed of pelagic eggs and

larvae of numerous species. Buoyant eggs and larvae remain in the plankton from 10 to 100 days, depending on the species (MMS 2007b).

No studies of the reactions of fishes to routine exploration activities in the OCS have been conducted, but the published scientific literature can be extrapolated to support an impact assessment of the proposed action, as described below.

4.5.3.1 Imp acts of Drillship and Support Vessels on Fishes

The drillship and support vessels could affect fishes by serving as a FAD, producing noise and light, and physically colliding with fish in the water. Each of these potential IPFs is discussed below.

F ish Aggregating Device. Fixed oil and gas platforms are known to act as FADs, which are typically defined as floating objects moored at specific locations in the ocean to attract pelagic fishes. Virtually any floating object in open water can serve as a FAD . Commercial, recreational, and artisanal fishers throughout the world purposefully deploy FADs to draw pelagic fish to targeted capture areas (Fisheries and Aquaculture 2010). It is debatable whether these devices actually cause fish to aggregate or onl y attract fish. Ideally, FADs function as floating reefs in the sense that they provide clean attachment locations for algae and invertebrates, which then provide forage, shelter, and structure for mobile organisms.

The drillship would not create comple x habitat in the same way as a fixed platform because the drillship is designed not to accumulate encrusting organisms on its hull. However, as a large floating object, it may serve as a temporary aggregating device for mobile pelagic fishes. The commerci al fishing interests that harvest tuna from the Gulf of Mexico would not set their lines beneath the drillship, and so tuna and other pelagic fishes that are attracted to the drillship would be temporarily protected from capture. The physical presence of the drillship would have a minor temporary beneficial effect on pelagic fishes such as tuna because it creates a temporary no

- take zone that would protect some individuals from fishing

pressure.

Sound. The drillship and support vessels will generate soun ds that could be perceived by marine fishes. All fish have two sensory systems that are used to detect sound in the water: the inner ear, which functions very much like the inner ear found in other vertebrates, and the lateral line, which consists of a

se ries of receptors along the body of the fish (Popper 2008). The inner ear generally detects higher frequency sounds while the lateral line detects water motion at low frequencies (below a few hundredHz). It is difficult to discern the impacts of sound al one because vessels tend to produce sound and

movement at the same time.

The physiological responses of marine fishes to vessel movements (Brown and Murphy 2010) and underwater noise (Popper 2003; Codarin and others 2009; Slabbekoorn and others 2010; Wri ght and others 2010) have been investigated for only a limited number of marine fishes (Popper and Hastings 2009a,b). Underwater sounds such as engine noise generated from all vessel types have been

demonstrated to elicit various responses in such fishes a s Pacific herring ( Clupea pallasii ), Atlantic cod ( Gadus morhua

), haddock ( Melanogrammus aeglefinus ), and sea bass, as described by Buscaino and others (2010), Popper (2003) and Popper and Hastings (2009a, b). The physiological structure of hearing

in fis hes results in different responses to underwater human

- made sounds, compared with marine mammals (Popper and others 2007); in most cases, human

- made sound is not expected to affect marine fishes at all (Kane and others 2010). Sounds associated with the pro posed action would have no significant impact on fishes,

Light. Artificial lighting associated with fixed oil and gas platforms is known to attract fishes, especially larval and juvenile stages of phototactic species (Lindquist and others 2005; Keenan 2007). Although no specific studies of similar effects of lighting on drillships have been published, it is reasonable to assume that fishes would react comparably. The increased lighting associated with the proposed action may alter

the behavior of indi vidual fish in the vicinity of the drillship. This temporary change in the behaior of individual fish is not expected to have any population

- level consequences or to affect the overall health of fish stocks. Artificial lighting would cause no significant i mpact to fishes.

4.5.3.2 Impacts of Water Intake on Fishes

Seawater will be drawn from several meters below the ocean surface for various services including fire

water and once

- through, non

- contact cooling of machinery on the drilling rig. Cooling wate r intakes can impinge or entrain pelagic organisms, leading to injury or mortality. Under Section 316(b) of the Clean Water Act, cooling water intakes must use BTA to minimize impingement and entrainment of organisms. EPA recently expanded the Section 31 6(b) regulations to include ―new, non

- fixed‖ facilities such as the

Noble Globetrotter (implemented via EPA NPDES General Permit GMG 290000). The Noble Globetrotter will be in full compliance with the BTA requirements specified in the NPDES permit. No sig nificant impact to ichthyoplankton or larger pelagic organisms would occur as a result of cooling water intake.

4.5.3.3 Impacts of Permitted Effluent on Fishes

Effluent discharges for the proposed action would be permitted under EPA NPDES General Perm it

No. GMG 290000 ( see Initial EP Section 7 ). Effluents would include water

- based drilling mud and cuttings, excess cement slurry, SBM, water

- based blowout prevention fluid, treated bilge water, treated chemical product waste, non

- contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated fire water, and ballast water.

Effluents discharged at the water surface, including treated SBM cuttings, would quickly become diluted by the receiving waters and not cause any significant impacts to fishes. Cuttings and excess cement slurry released at the sea floor would increase turbidity in only a localized area where few fishes are expected to occur.

4.5.4 Impacts of a Small Fuel Spill on Fishes

The Multisal e and Supplemental EISs concluded that a small fuel or chemical spills would not significantly affect fishes in the deep Gulf of Mexico (MMS 2007b, 2008; BOEM 2011a). The proposed action does not include any unique activities that would change the conclus ions of the regional EISs. A small fuel spill is the most likely type of spill to result from the proposed action, based on the history of exploration and development in the OCS. The programmatic Multisale EIS (MMS 2007b) concluded that aminor diesel sp ill (less than 1,000 bbl) is the most likely type of accident to occur during typical offshore

activities. The 1,000 bbl is an overestimate of the actual size of most spills in the Central Planning Area,

which tend to be less than 1 bbl (MMS 2007b). The median size of spills between 1 and 10 bbl is 3 bbl (MMS 2007b). Most small spills of this type result from a ruptured hose during fuel transfer.

A s outlined in Section 2.2.1 , a small fuel or chemical spill is extremely un likely to cause any significant impact to fishes beyond individuals in the immediate localized area (NOAA 2006). Shell‘s approach to minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 9b . Shell‘s OSRP includes p rotocols for containing and cleaning up small fuel or chemical spills. The specific procedures would vary depending on the product spilled, location (nearshore or offshore), sea state, weather, and other immediate conditions. Regardless of the particular cleanup methods, a small spill (3 bbl) would be quickly contained and recovered, causing no long

- term impact to fishes or habitat.

Diesel spills are particularly short

- lived because diesel floats on the sea surface, where its low molecular

weight constit uents readily volatilize (NRC 2003). Higher weight constituents that remain in the waters undergo microbial degradation and oxidation, resulting in short chain carbon compounds. If the spill occurs near shore, some of the diesel may enter coastal vegetat ed habitats for a brief time. However, microbial degradation would occur in the vegetated areas as well, and impacts would be transient (NOAA 2006). It is expected that small fuel spills will occur predominantly in the open Gulf of Mexico, where no signif icant impacts to fishes would result, because most fuel transfers occur at the drillship

rather than nearshore.

The proposed action would occur 79 miles (127 km) from the nearest shoreline ( Figure 1 ). Quantitative spatial modeling that incorporates degradation and breakdown of the fuel, as well as actual paths of historical spills, concluded that fishes are not at significant risk of spills smaller than 1,000 bbl (MMS 2007b).

Although it is possib le that other chemicals would be spilled, the probabilities are exceedingly small. The final Multisale Supplemental EIS (MMS 2008) applied the same evaluation to small spills of fuel and other chemicals and concluded that chemical spills were not likely t o cause significant impacts to fishes. More than 20 chemicals typically used in deepwater OCS activities were evaluated for toxicity to marine organisms. None of the chemicals to be used in the proposed action poses a risk to fishes in the volumes

used i n deepwater projects.

4.5.5 Impacts of a Large Oil Spill on Fishes

Nearshore assemblages of both adult fishes and ichthyoplankton may be particularly vulnerable to large oil spills because of high population densities. Most of the economically and recre ationally important finfish in the Gulf of Mexico depend at least in part on vegetated coastal habitats in the northern Gulf of Mexico, especially west of the Mississippi River (NOAA 2010). Nearshore and estuarine spawning in spring and summer produces pe aks of ichthyoplankton abundance as waters begin to warm each year (Hernandez and others 2010). A large oil spill would have greater effects on a larger number of species if it occurred during a time of dense ichthyoplankton aggregations (MMS 2007b).

Adult fishes are known to actively avoid water contaminated with oil. Most fishes would leave the oiled area and not experience prolonged exposure to oil. Limited data available on the long

- term effect of the

DWH event on bluefin tuna indicate that no ad verse effects have been realized. Eight tagged adult bluefin tuna known to spend time near the Macondo well were tracked for several months after the spill and shown to be doing well (Atlantic Bluefin Tuna Status Review Team [ABTSMT] 2011). Fish eggs and larvae (as well as other plankton) are not able to leave and would likely be adversely affected by the oil. Many eggs and larvae occur in the topmost layers of the water and would be exposed to floating oil. Oil and ichthyoplankton both tend to accumula te in convergence zones, where the incidence of exposure

would be increased.A large oil spill could significantly affect numerous individual fishes, but would not cause permanent loss

of any fish populations. The anticipated impacts of the DWH event on marine fishes have not materialized to any great extent. Despite the extensive spread of oil in the northern Gulf of Mexico, the species composition of nearshore fishes using seagrass nurseries was unaffected (Fodrie and Heck 2011). Likewise, the bluefin tuna population, which has been in decline and was directly affected by the DWH event, is not expected to experience long

- term losses resulting from the spill. Even though up to 20 percent of its spawning habitat in the Gulf of Mexico was oiled, quantita tive models predict that no population

- level effects will result, partly as a result of natural density

- dependent population

- level processes (ABTSMT 2011). The specific impacts would depend on the time of year, the meteorological conditions at the time, t he response action, and other variables.

However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial EP Section 2j ) that have been enhanced since the DWH event. In the

event that a blowout occurred, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant population

- level impacts to coastal or offshore fishes would result from a large spill.

4.5.6 Impact of Vessel Collisions on Fishes

Collision with vessels is not considered a major threat to most marine fishes (Kappel 2005). Whale sharks are an exception because of their large size and basking behavior. Numerous collisions of vessels with whale sharks have been recorded (Rowat and others 2007; Stevens 2007). Shell contracts with licensed support vessels operators who are responsible for compliance with all requirements reg arding transit lanes and speed restrictions. Vessel collisions would not significantly affect any fish or fisheries

resources.

4.5.7 Impacts on Essential Fish Habitat

The Gulf of Mexico Fisheries Management Council (GMFMC) and NMFS have identified waters and substrate necessary to fish for spawning, breeding, feeding, and growing to maturity as EFH. The GMFMC has developed Fishery Management Plans for several groups of commercially, recreationally, and ecologically important organisms, including corals an d coral reefs, shrimp, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. Virtually the entire northern coast of the Gulf of Mexico to a depth of about 600 feet (183 m) has been identified as EFH for at least one speci es. EFH for corals and coral reefs includes shallow topographic features in the Central and Western Planning Areas. The only EFH in the offshore waters near the lease area is for highly migratory pelagic fishes, including sharks, tunas, swordfish, and b illfishes (NMFS 2011a). Highly migratory species with EFH in the lease

area are listed in Table 5

.Table 5. Highly Migratory Fish Species in the Lease Block

Common Name Scientific Name Lifestage at Lease Location

Whale shark Rhincodon typus All Bigeye thresher shark Alopias superciliosus All Longfin mako shark Isurus paucus All Silky shark Carcharhinus falciformes All Oceanic whitetip shark Carcharhinus longimanus All Skipjack tuna Katsuwonus pelamis Adults, Spawning Adults, Juveniles

Yellowfin tuna Thunnus albacares Adults, Spawning Adults, Juveniles

Bluefin tuna Thunnus thynnus Eggs, Larvae

Swordfish Xiphias gladius Juvenile, Larvae

White marlin Tetrapturus albidus Adult, Juvenile Roundscale spearfish Tetrapturus georgii Adult, Juvenile

Blue marlin Makaira nigricans Adult

Source: NMFS 2009 a ; 2011a

NMFS also designated an area of about 15,000 square miles (mi 2 ) (300,000 square kilometers [km 2 ]) in the Gulf of Mexico as a habitat area of particular con cern (HAPC) because the Gulf of Mexico is believed to be the primary spawning area for western Atlantic bluefin tuna (ABTSRT 2011). It is thought that bluefin tuna larvae rear in the Gulf of Mexico until June, when they migrate to the Atlantic coast (ABTS RT 2011). HAPCs are defined as areas that are rare, particularly susceptible to human

- induced degradation, especially ecologically important, or located in an environmentally stressed area. The Magnuson

- Stevens Act does not provide for any additional pro tection of HAPCs, but NMFS considers adverse impacts to HAPCs more significant than impacts to EFH in general.

Most of the deepwater oil and gas exploration and development sites fall within EFH for highly migratory species, particularly for the bluefin t una. Gulf waters ―west of 86° W and seaward of the 100 m isobath, extending from the 100 m isobath to the Exclusive Economic Zone (EEZ)‖ are considered HAPC; the lease area is within the HAPC ( Figure 3 ). At least 175 oil and gas platforms currently exist within HAPC for bluefin tuna (NMFS 2009a). No other HAPC occurs within the project area (GMFMC 2005) ( Figure 3 ).

The Multisale EIS found that no routine IPFs associated with exploration activities would significantly affect EFH (MMS 2007b). The site

- specific SEA S

- 7445 for a nearby lease corroborated that finding ( BOEM 2011b). Routine permitted discharges of drilling fluids and cuttings offshore would cause transient impacts to water quality, but would not significantly degrade EFH because the discharges would be immediately diluted by receiving waters. The proposed action would occur in a localized area for a limited duration; no lasting reduction in EFH quality would result. As discussed in Section 4.5.3.1 , the drillship itself would temporarily add a physical structure to an otherwise featureless area of the open Gulf. The drillship may act as a transient FAD while it is at the project site. Drillships and rigs mo ve about the Gulf of Mexico intermittently as they are contracted for various projects. They offer familiar but movable structures within the larger OCS area and are not expected to represent an adverse modification or degradation of any EFH.

4.5.4.1 I mpacts of a Small Fuel or Chemical Spill on Essential Fish Habitat

The Multisale and Supplemental EISs evaluated effects of a small fuel or chemical spill on EFH in the Gulf of Mexico and found no significant impact (MMS 2007b, 2008; BOEM 2011a). The pr oposed action does not include any unique activities that would change the conclusions of the regional EISs. Likewise, the

site

- specific SEA S

- 7445 in a nearby lease block concluded that small spills were unlikely to result in anysignificant impacts to E FH ( BOEM 2011b). These documents are incorporated by reference and are

considered to support the conclusions of this EIA.

As outlined in Section 2.2.1 , a small fuel or chemical spill is extremely unlikely to cause any significant impact beyond the immediate project area. Shell‘s approach to minimizing the risk of fuel or chemical spills is discussed further in the Initial EP Section 9b . Shell‘s OSRP i ncludes protocols for containing and cleaning up small fuel or chemical spills. The specific procedures would vary depending on the product spilled, location (nearshore or offshore), sea state, weather, and other immediate conditions. Regardless of the p articular cleanup methods, a small spill (3 bbl) would be quickly contained and recovered, causing no long

- term impact to EFH. It is possible that a limited area of EFH (or HAPC) could be temporarily degraded by a small spill that caused a short

- term impa ct on water quality because the project area is within HAPC for the bluefin tuna and other highly migratory pelagic fishes. The project area represents a negligible fraction of the 114,793 mi 2 (297,312 km 2 ) bluefin tuna HAPC.

A small fuel or chemical spi ll would dissipate or be collected before it could be transported more than a few miles from the lease area (NOAA 2006). No long

- term significant impacts to EFH or HAPC would result from a small fuel or chemical spill under the proposed action.

4.5.4.2 Impacts of a Large Oil Spill on Essential Fish Habitat

A large oil spill was analyzed in the Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a)

and site

- specific SEA S

- 7445 in a nearby lease block ( BOEM 2011b). The proposed action does not

in clude any unique activities that would change the conclusions of the regional EISs or site

- specific SEA. A large oil spill in the project area would unavoidably affect some EFH because of the vast area of the Gulf that is identified as EFH (GMFMC 2005, NM FS 2009a). Impacts to water quality would be temporary but potentially widespread, depending on meteorological conditions at the time. A large spill could affect the EFH for virtually all managed species in the northern Gulf of Mexico, including shrimp, stone crab, spiny lobster, coral and coral reefs, reef fishes, coastal migratory pelagic fishes, and red drum. Any impact that decreased the functional quality of the habitat would be considered an impact to EFH

because EFH is defined in functional terms. Impacts include degraded water quality; decreases in the abundance or quality of prey species (phytoplankton, zooplankton, ichthyoplankton, and nekton); oiled sediments; and increased physical disturbance (GMFMC 2005).

A significant impact would occur to the extent that the oil spill caused a reduction in the quantity or quality of forage within the EFH for highly migratory species. However, most forage and predator species would relocate for a time until the water quality had been restored to pre

- spi ll conditions. Floating Sargassum is EFH for the juvenile life stages of a number of managed recreational and commercial fishery species, including dolphin fish ( Coryphaena hippurus ), marlin ( Makaira nigricans) , sailfish ( Istiophorus platypterus ), cobia ( Rachycentron canadum ), gray triggerfish ( Sufflamen bursa ), and amberjack (Carangidae). If oil accumulated on the Sargassum mats, the quality of EFH would decline temporarily. The increase in human activity associated with a spill response could degrade t he quality of EFH for a short while, and containment materials could introduce an entanglement risk to highly migratory species. However, these effects are considered short

- term and not significant.

The project area is within HAPC for the bluefin tuna. The extent to which a large spill would cause significant impacts to the bluefin tuna HAPC depends in part on the timing of the spill (ABTSRT 2011). The HAPC is designated based on the importance of the area to bluefin tuna eggs and larvae. If the spil l occurred early in the summer while eggs and larvae were present, a significant impact to the HAPC (and to the species) could occur. Later in the summer (after June), no eggs or larvae are present in the area, and the impacts would be less significant.

If the spilled oil reached coastal EFH, impacts could be longer

- lived and more severe. Adult fishes may be capable of detoxifying ingested oil to some extent and relocating until conditions improve. Larval andj uvenile fish are less able to process in gested oil and may suffer toxic effects ( BOEM 2011a). In many

fish species, eggs are the most vulnerable life stage. The probability that oil would reach the more sensitive EFH areas is low because a large spill is extremely unlikely to occur. In the ev ent that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, the proposed action is not likely to degrade or adversely modify EFH.

4.6 Sea Turtles (Endangered/Threatened)

All five sea turtle species that occur in the northern Gulf of Mexico are listed as threatened or endangered under the ESA ( Table 6 ). All of them could occur near the project area and in coastal waters ( Initial

EP Section 6h ).

Table 6. Federally Listed Sea Turtles in the Northern Gulf of Mexico

Sea Turtles Scientific Name Status

Green turtle Chelonia mydas T, E b

Hawksbill turtle Eretmochelys imbricata E Kemp‘s ridley turtle Lepidochelys kempii E
Leatherback turtle Dermochelys coriacea E Loggerhead turtle Caretta caretta T

b Only the Florida breeding population is endangered.

4.6.1 Baseline Conditions of Sea Turtles

Juveniles of all Gulf of Mexico sea turtles occur in the general project vicinity, feeding on or near mats of floating Sargassum or other material. As adults, only the leatherback and loggerhead sea turtles are likely to occur near the drillship. The gre en sea turtle tends to stay in coastal forging areas, although it occurs in convergence zones of the open Gulf of Mexico. The hawksbill sea turtle is most closely associated with areas of topographic relief such as coral reefs, ledges, caves, and rocky ou tcrops, or high energy bottoms where upwelling may occur. The Kemp‘s ridley sea turtle is rarely found in water below 160 feet (49 m).

After they hatch on a high

- energy sandy beach, a sea turtle moves among various habitats as it grows. Hatchlings and j uveniles tend to favor pelagic convergence zones where food is plentiful. As adults, green, hawksbill, and loggerhead turtles forage primarily in shallow, benthic habitats. Leatherbacks remain in the open Gulf, feeding primarily on jellyfish.

Species p rofiles of sea turtles, including preferred nesting locations, were presented in the Multisale EIS (MMS 2007b), which is incorporated by reference. The most important sea turtle nesting areas on Gulf of Mexico beaches are in Florida (green, loggerhead, an d leatherback) and Texas (loggerhead and Kemp‘s ridley) (FFWCC 2010, NMFS and others 2010, Sea Turtle Restoration Project 2011; Share the Beach 2010; BOEM 2011a).

4.6.2 Impacts of Routine Activities on Sea Turtles

Routine IPFs that could affect sea turtle s include noise and lights of the drillship and physical disturbance of support vessels and helicopters. IPFs resulting from accidents include a small fuel or chemical spill, a large oil spill, and vessel strikes ( Sections 4.6.3 through 4.6.5 ).

Neither permitted discharges nor marine debris is considered an IPF of the proposed action. Permitted discharges from the drillship and support vessels would not pose any significant impact to se a turtles because discharges would disperse quickly, remain localized, occur intermittently, and not contain toxicconstituents (see Section 4.2.1 .). Shell‘s standard protocols for managing marine debris would minimize

the potential for impacts to sea turtles, in compliance with NTL 2007

- G03.

The Multisale EIS (MMS 2007b) and site

- specific SEA S

- 7445 ( BOEM 2011b) evaluated potential impacts to sea turtles. Neither noise and lights nor the physical presence of the dril lship and support vessels were identified as IPFs for sea turtles in those documents, which are incorporated by reference into this EIA. NMFS concluded in its Biological Opinion that effects to sea turtles from vessel noise are

discountable because vessel noise does not propagate far from the vessel, and sea turtles are not particularly attuned to auditory cues (NMFS 2007). Helicopter noise is not considered to cause a significant impact to sea turtles. Pilots maintain altitudes above 700 feet (213 m) dur ing transit to and from the working area and do not hover over or follow sea turtles.

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that would be used to drill the proposed wells works regularly in th e deepwater Gulf of Mexico, moving from site to site as needed. The proposed action would represent a minor increase in noise, lights, and physical disturbance in a limited spatial area. Based on the limited spatial area and temporary nature of

the distu rbance in the context of the overall Gulf of Mexico environment, the routine IPFs associated with the proposed action is not likely to adversely affect sea turtles.

Some sea turtles, especially loggerheads, have been observed preferentially congregating near offshore structures (Lohoefener and others 1990). The turtles‘ attraction to structures such as oil platforms supports the conclusion that these animals are not adversely affected by the noise, lights, and activities associated with oil and gas expl oration. Although artificial lighting is known to disrupt the orientation behavior of nesting females and hatchlings emerging from nests, lighting is not a key orientation cue in offshore waters (Witherington 1997, Tuxbury and Salmon 2005, Salmon and Wyne ken 1990). Likewise, NMFS (2007) concluded that the effect of lighting from the drillship on sea turtles is insignificant.

4.6.3 Impacts of a Small Fuel or Chemical Spill in Sea Turtles

The potential for a small fuel or chemical spill to adversely affec t sea turtles was evaluated in regional Multisale EISs (MMS 2007b, 2008; BOEM 2011a) and in NMFS‘s 2007 Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. The

scientific litera ture on the impacts of fuel and oil spills on sea turtles is reviewed within the EISs and the Biological Opinion and is incorporated by reference into this EIA. The proposed action does not include any unique or unusual activities that were not evaluated in the regional EISs and the Biological Opinion. There are no unique site

- specific issues with respect to spill impacts on sea turtles for this Initial EP.

Shell‘s rigorous training program and standard operating procedures minimize the incidence of fuel and chemical spills. If a small fuel or chemical spill were to occur, it would be quickly contained and cleaned up in accordance with Shell‘s OSRP, as described in Initial EP Sections 2j and 9b.

A small fuel or chemical spill would disperse quickly, r emain localized, occur intermittently, and not

contain toxic constituents at levels that could cause irreversible adverse effects in sea turtles. Most sea turtles remain in coastal waters and would not occur in the vicinity of the drillship. The project area is

79 miles (127 km) from the nearest shoreline in Louisiana and a large distance from important sea turtle nesting beaches in Texas and Florida. A small fuel or chemical spill would not be expected to make

landfall or reach coastal waters before it broke up.

For these reasons, a small fuel or chemical spill would not adversely affect sea turtles. As described in

Section 2.2.1 , the most common fuel spill is diesel, which remains near the water‘s surface and dissipates rapidly (NOAA 2006). A sea turtle exposed to diesel in the water could experience skin irritation and sloughing; inhalation of toxic fumes leading to temporary changes in blood chemistry; ingestion of oil directly or via contaminated prey; and stress fro m the activities and noise of response vessels and aircraft (NOAA 2003, NMFS 2010b). The small likelihood of occurrence, the limited spatial extent of the projectarea, the temporary nature of a small fuel or chemical spill, and the low density of sea tur tles in the

project area make it highly improbable that sea turtles would actually be exposed to a small spill. For these reasons, a small spill is not likely to adversely affect sea turtles.

4.6.4 Impacts of a Large Oil Spill on Sea Turtles

A blowout leading to a large oil spill could adversely affect sea turtles directly and indirectly. Individual sea turtles that are in the immediate area when a blowout occurs could be harassed, injured, or killed. A high concentration of response vessels could place sea turtles at a greater risk of fatal injuries from vessel collisions (discussed in Section 4.6.5 ).

A large oil spill could have immediate direct and subsequent indirect adverse effects on sea turtles. Immediate direct adverse effects could include exposure to oil through dermal, ingestion, and inhalation pathways. Indirect adverse effects of the spill could include ingestion of contaminated prey and subsequent intestinal blockages (NMFS 2003).

Dermal exposure of sea turtles to spilled oil could cause sloughing of skin, especially around the neck, leading to infection. Sea turtles are also vulnerable to inhalation of toxic fumes during an oil spill. They inhale deeply before diving and resurface frequently. Neither juvenile nor adult sea turtles appear to actively avoid oil spill areas, making them vulnerable to repeated bouts of inhalation if the s pill covers a large area. Inhalation of petroleum vapors can cause temporary changes in the turtle‘s blood chemistry (NOAA 2003).

Sea turtles exposed to a large spill would ingest oil directly and with contaminated prey. Sea turtles appear to continue c ongregating and feeding in convergence zones even when oil is present. The oil ingested by a turtle takes several days to pass through the gut. Prolonged contact of the ingested oil with internal membranes increases the absorption of toxic constituents. Turtles that have ingested oil are more likely to suffer secondary physical impaction of the intestines, leading to physical distress and even starvation (NOAA 2003). Turtles may be affected for some time after a spill because they readily eat tarballs, which cause adverse effects including gut blockage, toxicity, bloating, and difficulties maintaining buoyancy. All of these effects increase the turtles‘ susceptibility to predation and vessel strikes (NOAA 2003). Toxic effects of oil exposure through all pathways include impairment of the immune and reproductive systems, physiological stress, declining physical condition, and death. They experience repeated, prolonged exposure to oil in the water and in their food because sea turtles do not exhibit behav ioral avoidance of oiled waters. Indirect effects of a large spill on sea turtles include declines in the availability or quality of prey, long

- term immune deficiencies, and disturbance of reproductive patterns (NOAA 2003; NMFS 2007).

In addition to impa cts of the oil spill itself, the human response effort could also stress sea turtles (NOAA 2003, 2010). Increased vessel, helicopter, and fixed

- wing aircraft traffic would introduce additional noise and risk of vessel strikes. Response vessels would oper ate in accordance with NTL 2007

- G04 to reduce the potential for striking or disturbing sea turtles. Marine debris in the form of containment materials could result in ingestion and entanglement problems. Sea turtles tend to eat anything of the appropriat e size, including plastic. Use of dispersants could cause additional direct toxicity to the sea turtles or interrupt the food web that supports them (NOAA 2003, 2010; NMFS 2007).

The likelihood of any or all of these impacts actually occurring depends on the period of exposure, the condition of the individual turtle before exposure, and the characteristics of the spilled oil. The most likely direct impact would be through the inhalation pathway during the early phase of the spill. Inhaled

fumes absorbed into the sea turtles‘ bloodstream can cause a cascade of physiological effects (NOAA 2003).Individual sea turtles could be adversely affected by a large spill under the proposed action. However, a

large spill is extremely unlikely to occur because Sh ell has rigorous well control and blowout prevention measures (see Initial EP Section 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil. Initial

EP Sect ions 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no significant spill impacts on sea turtles are expected.

Oil from a large spill could reach the shorelines in Louisiana, Mississippi, Alabama, and Florida, where

some sea turtle n esting occurs (Share the Beach 2010). The OSRA model predicts a 21 percent probability that this area could receive oil within 30 days of a large release ( Table 4 ). The effect of spilled oil on s ea turtle nests depends on the timing of the spill with respect to nesting. If the beach is already oiled, the female may choose not to nest there, or to forego nesting entirely that year. If the water is oily at the time the hatchlings emerge, the hatchlings would be directly exposed via a ll of the pathways described above (NOAA 2003; NMFS 2007).

Oiled and dead sea turtles were collected for several months after the DWH event. Researchers are still performing necropsies, and it may be some time before the total number of mortalities is kn own. At this time, approximately 600 turtle mortalities have been reported associated with the oil spill. More than 75 percent of the mortalities were Kemp‘s ridley turtles. Smaller numbers of loggerhead and green turtles were reported killed. An addit ional 400 or so oiled turtles were collected, cleaned, and released back to the wild (NOAA 2011). Almost 300 turtle nests were translocated (271 loggerhead, four Kemp‘s ridley, and three green turtles) and more than 14,000 hatchlings were released into cl ean waters to protect them from the oil spill (NMFS 2010b).

Individual sea turtles could be adversely affected by a large oil spill under the proposed action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control a nd blowout prevention measures (see Initial EP Section 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil. Initial

EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, the proposed action is not likely to adversely affect sea turtles.

4.6.5 Impact of Vessel Strikes on Sea Turtles

Collisions with vessels are a common cause of injury to sea turtles. Vessel

- relate d injuries are more likely to occur in areas with high boating traffic (NMFS and FWS 2009). Although sea turtles likely hear and see approaching vessels, they may not be able to avoid all collisions. High

- speed collisions with large

vessels can be fatal to sea turtles. The risk probability of a physical strike is related to the size and speed on the vessel, with larger, faster vessels causing substantially more injury than smaller vessels.

The reaction of a sea turtle to a collision would depend on the severity of the collision. Minor strikes would cause temporary reversible effects, such as diverting the turtle from its previous activity or causing

short

- term pain. Major strikes are those that can cause permanent injury or death from bleeding,

infect ion, or inability to feed. Apart from the severity of the physical strike, the likelihood and rate of a turtle‘s recovery from a strike may be influenced by its age, reproductive state, and general condition. Much of what is written about recovery from v essel strikes is inferred from observing individuals some time after a strike. Numerous sea turtles bear scars that appear to have been caused by propeller cuts or collisions with vessel hulls (Lutcavage and others 1997; Hazel and others 2007). Conversely , fresh wounds on some stranded animals may strongly suggest a vessel strike as the cause of death. The actual incidence of recovery versus death cannot be inferred from available data.

Shell‘s compliance with BOEM ‘s protective measures, outlined in NTL 2007

- G04, reduces the potential for collisions between vessels and sea turtles. Vessel operators are trained to identify and avoid sea turtles to the extent practicable, maintaining a distance of at least 150 feet ( 45 m). Given the protective measures and the relatively low chance of an encounter between sea turtles and support vessels overdeep waters, vessel strikes near the project site are unlikely. The likelihood of strikes increases in coastal

waters, but ves sels operate in defined boat lanes near shore. Boating lanes are designated in areas without the habitat features that may attract sea turtles, reducing the likelihood of vessel strikes.

The Biological Opinion for the Five

- Year Oil and Gas Leasing Progr am in the Central and Western Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007

- G04 would reduce the likelihood of collisions between vessels and sea turtles to insignificant levels (NMFS 2007).

The proposed action is not expe cted to result in any significant effect on breeding, feeding, or sheltering to individual sea turtles or have any consequences to populations of turtles. Shell‘s compliance with all mitigation and protective measures would reduce the potential for advers e effects on sea turtles to non

significant levels.

4.7 Coastal and Marine Birds and Critical Habitat

Dozens of marine and coastal avian species occur in the northern Gulf of Mexico. Although some species are more ―marine‖ and others more ―coastal,‖ thes e general distributional categories overlap. Coastal birds sometimes occur over offshore waters, especially when migrating. Conversely, many marine (pelagic) species nest on the coast. The time of year in which a spill occurred would have a great

influe nce on the types and numbers of birds that were affected, as many species in the project area are migrants that occur in the area during only part of the year, and even year

- round residents may change habitats throughout the year. Avian species and their critical habitat protected under the ESA are

evaluated in Section 4.7.1 ( Table 7 ); impacts to other coastal and marine birds are discussed in Section

4.7. 2

.

4.7.1 Threatened and Endangered Birds

Potential impacts of the proposed action on the threatened piping plover and the endangered whooping crane were analyzed in the Multisale EIS (MMS 2007b) and the site

- specific SEA S

- 7445 ( BOEM 2011b). Additional information made available since the publication of those documents is included below.

Table 7. Federally Listed Birds in the Northern Gulf of Mexico

Birds Scientific Name Status Designated Critical Habitat

Piping Plover Charadrius melodus Threatened All Gulf of Mexico Coastal States

Whooping Crane Grus americana Endangered Coastal Texas (Aransas National Wildlife Refuge)

4.7.1.1 Piping Plover

The piping plover is federally

- listed as threatened in all Gulf of Mexico coastal states. The piping plover is a small, stocky, light

- colored shorebird with distinctive orange legs, a black neck band, and a black brow during the breeding season. The piping plover inhabits and feeds in coastal and island beaches, mudflats, and sandflat s. Individuals that overwinter on the Gulf of Mexico coast may belong to any of three populations that breed in the Great Lakes, the Northern Great Plains, or the Atlantic coast (FWS 2009a). The Great Plains population is listed as endangered and the othe r two as threatened. Major threats to the piping plover are habitat loss and degradation resulting from coastal development, disturbance by humans and pets, and predation (FWS 2009a). Critical overwintering habitat has been designated on shorelines of al l Gulf Coast states ( Figure 3 ). This bird feeds on retreating tides by probing for invertebrates at or just below the ground surface. It roosts, rests, and preens on beaches above where it forages (FWS 2010a). Additional species de scription is available in the Multisale EIS (MMS 2007b).In the extremely unlikely event of a large oil spill, oil from the project area could reach piping plover

critical habitat in Louisiana, Mississippi, Alabama, and the Florida Panhandle within 30 days . The lease

area is 79 miles (127 km) from the nearest piping plover habitat in Plaquemines Parish, Louisiana ( Table 4 ).

If oil were to reach the beaches where t he piping plover overwinters, birds could become externally oiled

while roosting or foraging. They could also ingest oil as they forage along tidal channels and shorelines at the water‘s edge. They would be expected to incidentally ingest oil adsorbed to the sediment and to take in oil as they preen. Some piping plovers co uld suffer illness or death if exposed to substantial amounts of oil. More individuals would be affected if a large spill occurred during winter when the plover

is most abundant in the area. Degradation of critical habitat could occur during any season, but the degree of harm would depend on the opportunity for the habitat to recover before the birds returned in the fall. In addition to the direct effects of oil on the shoreline, vehicular traffic and other human activities associated with the spill resp onse could adversely affect the piping plover or degrade its critical habitat. Shell‘s commitment and available resources to protect and rehabilitate wildlife in the event of a spill are described in its OSRP.

Individual piping plovers could be adversely affected by a large oil spill under the proposed action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial EP Section 2j ). In the event that a large oil spill did o ccur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil.

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, the action is not likely to adversely affect the pi ping plover or to result in any degradation of its critical habitat.

4.7.1.2 Whooping Crane

The federally listed endangered whooping crane is a large omnivorous wading bird. Most of the free

ranging whooping cranes in the world winter on the Aransas National Wildlife Refuge (NWR) in Texas and breed in Canada. As of December, 2008, a total of 270 individuals were recorded there (Whooping Crane Eastern Partnership [WCEP] 2010). Other populations have been established in Florida and Wisconsin in

an att empt to secure the species. Historically, the whooping crane occurred widely in many types of wetland habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (FWS 2007, WCEP 2010). Critical habitat designated in the Aransas NWR and adjacent islands provides important wintering grounds for the whooping crane ( Figure 3 ). Additional information on the whooping crane is in the Multisale EISs (MMS 2007b; BOEM 2011a)

.

The OSRA model shows that oil from the project area would not reach whooping crane critical habitat within 30 days. The project area is approximately 520 miles (837 km) from the Matagorda Unit of the Aransas NWR, Texas, where the whooping crane occur s. The oil is not expected to reach the shorelines of Matagorda County, Texas, which is an ―area of interest‖ for the whooping crane population (FWS 2009b). The proposed action would have no effect on the whooping crane because oil is not expected to

rea ch the shoreline where the crane overwinters.Figure 3

. Critical Habitat and Essential Fish Habitat in the Northern Gulf of Mexico

4.7.2 Other Coastal and Marine Birds

Birds not protected under the ESA may be protected under the Migratory Bird Treaty Act and various state wildlife statutes. The northern Gulf of Mexico provides habitat for both resident and migratory birds.

4.7.2.1 Baseline Conditions

Common marine b irds in the northern Gulf of Mexico include summer non

- breeding migrants (shearwaters, storm petrels, and boobies); summer breeding residents (sooty tern, least tern, sandwich tern, and magnificent frigatebird); winter non

- breeding residents (gannets, gull s, and jaegers); and permanent breeding residents (laughing gull, royal tern, and bridled tern) (Hess and Ribic 2000). Marine birds range widely across the Gulf and are not associated with any particular offshore location. T erns,
storm

- petrels, shearwate rs, and jaegers are the most likely to occur near the wellsite based on the water depth and distance from shore.

During spring and fall migration seasons, some coastal birds may occur near the well site as they make way across the Gulf of Mexico. Some individuals may stop to rest on offshore structures, although they are less likely to rest on a drillship than on a fixed platform (Russell 2005).Numerous coastal birds occur along the northern Gulf of Mexico coast, including diving birds, shorebirds,

marsh birds, wading birds, and waterfowl. Beaches, flats, dunes, bars, barrier islands, and similar habitats support nesting sites for the sandwich tern, Wilson‘s plover, black skimmer, Forster‘s tern, gull

billed tern, laughing gull, least tern, and royal tern (FWS 2010b). These species are considered especially vulnerable to a large oil spill that occurs during the b reeding season, as described in the Multisale EISs (MMS 2007b, 2008) and the site

- specific SEA S

- 7445 ( BOEM 2011b).

Although the brown pelican ( Pelecanus occidentalis ) was delisted from federal endangered status in 2009, it is still given special protection by the States of Mississippi and Florida (Mississippi Department of Wildlife, Fisheries and Parks 2011; FFWCC 2010). The brown pelican occurs primarily in coastal habitats and is rare in offshore waters (Fritts and Reynolds 1981, Peake 1996, Hess and Ribic 2000). It is a year

round resident of the Gulf Coast that nests on barrier islands.

4.7.2.2 Impacts of a Large Oil Spill on Other Coastal and Marine Birds

T he only potential IPF for coastal and marine birds is a large oil spill, which would expose a variety of species to oil (and possibly dispersants) via dermal, inhalation, and ingestion pathways. The effects of exposure to oil and dispersants vary among sp ecies, and are also mediated by the individual‘s age, physiological condition, reproductive status, and other variables.

Impacts of a large oil spill would be experienced first by birds in the open waters near the wellsite. Birds may be physically dist urbed by the blowout and surge of human activity during the response phase. Individual birds that did not leave the area in reaction to the physical disturbance would then become vulnerable to the direct effects of the oil, which could result from dermal, inhalation, and ingestion exposure. Both marine and coastal bird species were reported to be oiled during and after the DWH event (FWS 2010c). Coastal birds could be affected by a large spill within 30 days, based on the projected trajectory of the spil l ( Table 4 ). Approximately 5,000 dead birds and 2,000 live but oiled birds were collected during and after the spill (FWS 2010d). The most commonly collected oiled birds were laughing gull, Northern gannet, brown pelican, royal tern, black skimmer, and least tern. Other gulls and terns were also affected. The greatest numbers of avian mortalities were laughing gulls, brown pelicans, and northern gannets (FWS 2010d).

Like birds in the deeper waters, bi rds in nearshore habitats can be exposed to oil dermally or through ingestion. Inhalation is not expected to be a significant pathway for coastal birds because the more

volatile constituents in the oil would have had t ime to dissipate before the oil spill reached the coast. Direct exposure to oil may cause mortality. When their feathers absorb oil, birds may lose their ability to fly, thermoregulate, and maintain buoyancy control when diving (FWS 2010e). Many oiled b irds drown. If the spill occurs in winter, birds may die of hypothermia. Oil can cause an egg not to hatch by interfering with the gas exchange necessary to sustain the developing embryo. Direct toxicological effects to developing embryos vary with respe ct to the weathering of the oil and the age of the exposed embryo (Finch and others 2011). Freshly spilled oil is the most toxic to bird eggs.

Birds may ingest oil directly while foraging or preening or indirectly through their food. Once ingested, oil

m ay cause immediate toxic effects or physical obstruction of the gut that leads to death by starvation. Ingested oil may impair lung, liver, and kidney functions, leading to death from disease, starvation, or predation. More than 300 brown pelican mortali ties were reported after the DWH event. Potential causes of death included direct contact with oil, disturbance by cleanup activities, and ingestion of contaminated media (FWS 2010e; Finch and others 2011).

The actual extent of oiling in coastal habitats depends on the duration of the spill, meteorological conditions at the time, and the effectiveness of the response. Rigorous containment measures developed since the DWH event make it highly unlikely that such a widespread spill would occur again.Indi vidual marine and coastal birds could be adversely affected by a large oil spill under the proposed

action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial EP Secti on 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil.

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no signif icant population

- level impacts to coastal or marine birds would result from a large oil spill.

4.8 Marine Mammals

This section discusses all marine mammals that occur in the northern Gulf of Mexico. All marine mammals are protected under the MMPA; some are also listed as endangered or threatened under the

ESA.

Seven of the 29 species of marine mammals in the Gulf of Mexico are federally

- listed as endangered ( Table 8 ). The FWS has jurisdiction over the manatee; other endangered marine mammals in the Gulf of Mexico are the responsibility of NMFS. The FWS has designated critical habitat only for the manatee in peninsular Florida. No critical habitat for whales has bee n designated in the Gulf of Mexico.

Table 8. Federally Endangered Marine Mammals in the Northern Gulf of Mexico

Marine Mammals Scientific Name Potential Presence

Lease Area Coastal Odontocete (Toothed) Whales Sperm whale Physeter macrocephalus X

-- Mysticete (Baleen) Whales
Blue whale Balaenoptera musculus X a

-- Fin whale Balaenoptera physalus X a

-- Humpback whale Megaptera novaeangliae X a

-- North Atlantic right whale Eubalaena glacialis X a

-- Sei whale Balaenoptera borealis X a

-- Sirenians
Florida manatee Trichechus manatus latirostris

-- X

a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are unlikely to occur in the lease area (Würsig and others 2000).

4.8.1 Sperm Whale

The sperm whale is discussed in greatest detail in this EIA because it is the most common large whale in the northern Gulf of Mexico, it is federally listed as endangered, and NMFS has recently prepared a Biological Opinion on the sperm whale relevant to t he proposed action (NMFS 2007) and a 5

- year review and final recovery plan for the species (NMFS 2009b, 2010c). However, the IPFs and adverse effects described for the sperm whale also are applicable to most other marine mammals in the project area.

Othe r marine mammals are discussed in subsequent sections only to the extent that effects differ from those described for the sperm whale

.

4.8.1.1 Baseline Conditions The sperm whale is the most common large whale in the Gulf of Mexico and the only endange red marine mammal likely to occur near the project area (NMFS 2009b). The year

- round presence of sperm whales in the northern Gulf of Mexico indicates that this population may be ―resident,‖ meaning that individuals remain in the Gulf throughout their liv es (NMFS 2009b). The sperm whale is most abundant in waters at least 3,280 feet (1,000 m) deep near steep gradients (NMFS 2009b and references within).The Multisale EIS provides a description of the biology, life history, and distribution of the sperm w hale,

which is incorporated by reference (MMS 2007b; BOEM 2011a). Sperm whales move about the Gulf of Mexico in response to physical features such as the Gulf of Mexico Loop Current, upwellings, and other large

- scale oceanographic conditions (Jochens and others 2008). Female sperm whales tend to remain along the upper continental slope between the 656

- and 3,280

- foot (200

- and 1,000

- m) depth contours, whereas males occur on the upper slope as well as in waters more than 9,843 feet (3,000 m) deep. Sperm whales often occur in groups of about 10 individuals that may or may not be genetically related to each other. Groups of females with young may include relatives; groups of young bachelor males generally include individuals who are unrelated to each other (Jochens and others 2008). The area of greatest sperm whale density is north of the proposed project area in waters about 3,280 feet (1,000 m) deep. Adult male sperm whales may transit through the deeper waters of the project area, but are not expected to be abundant there (Jochens and others 2008).

Routine IPFs potentially affecting the sperm whale include noise and lights and physical disturbance of support vessels and helicopters. IPFs resulting from accidents include a small fuel or chemical spill, a large oil spill, and vessel strikes.

Neither permitted discharges nor marine debris is considered an IPF for the sperm whal e. Permitted discharges from the drillship and support vessels would not pose any significant impact to the sperm whale because they would disperse quickly, remain localized, occur intermittently, and not contain toxic constituents (see Section 4.2.2 ). Shell‘s standard protocols for managing marine debris would minimize the potential for impacts to sperm whales, in compliance with NTL 2007

- G03.

4.8.1.2 Impacts of Routine Activities on the Sperm Whale

The potential impacts of routine activities associated with oil and gas exploration on the sperm whale were evaluated by NMFS during its review of the EIS for the Five

- Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. NMFS prepared a Biological Opinion concluding that drilling noise and other associated activities were not likely to adversely affect the sperm whale (NMFS 2007). D rilling typically produces low sound source levels with amplitudes too low to

induce adverse effects in s perm whales (NMFS 2007). This position was reiterated in the 5

- year review of the status of the sperm whale, where NMFS reported that o il and gas exploration are ―believed to represent a relatively low level of threat at the current abundance of sperm wha les‖ (NMFS 2009b).

Helicopter traffic associated with offshore oil and gas exploration was analyzed for potential effects on the sperm whale. Sperm whales react behaviorally to helicopter overflights, but their reactions are not

considered adverse effect s (MMS 2007b, Smultea and others 2008). Helicopters supporting the proposed

action would maintain altitudes above 700 feet (213 m) during transit to and from the working area. Helicopter pilots do not typically approach or circle whales in the Gulf of Me xico during routine support flights. A whale may pause and dive during the brief period the helicopter is flying over, but this short

term behavioral effect is considered minor and temporary, with no long

- term biological significance.

The resident sperm whales in the Gulf of Mexico are exposed to noise, lights, and physical activity associated with oil and gas exploration, commercial fishing, and shipping. A study of the effects of small boats (whale watching tour boats) on the behavior of sperm whales i n the Southern Ocean indicated that whales become increasingly tolerant of the vessels when exposure is frequent (NMFS 2009b). The supply vessels that support the rigs and platforms may elicit similar habituation in sperm whales in areas of the

northern G ulf of Mexico where oil and gas activity is concentrated. (Habituation is the process whereby an animal ―ignores‖ a stimulus because it has learned that no response is warranted.)

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that would be used to drill the proposed wells works regularly in the deepwater Gulf of Mexico, moving from site to site as needed. The proposed action would represent a minor increase in noise, lights, andphysical disturbance t o a limited spatial area. Based on the limited spatial area and temporary nature of

the disturbance in the context of the overall Gulf of Mexico environment, the proposed action would not adversely affect the sperm whale.

Although noise, lights, and phys ical disturbance of the drillship and support vessels were considered potential factors affecting sperm whales, NMFS‘s Biological Opinion and 5

- year review support the conclusion that these activities are not IPFs for the sperm whale (NMFS 2007, 2009a). E xclusion of these activities as IPFs for the sperm whale is consistent with recent Multisale EISs (MMS 2007b, 2008; BOEM 2011a).

4.8.1.3 Impacts of a Small Fuel or Chemical Spill on the Sperm Whale

The potential for a small fuel or chemical spill to ad versely affect the sperm whale was evaluated in the regional Multisale EISs (MMS 2007b, 2008; BOEM 2011a) and in NMFS‘s 2007 Biological Opinion for the

Five

- Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. The scientific literature on the impacts of fuel and oil spills on marine mammals is reviewed in the EISs and the Biological Opinion and is incorporated by reference into this EIA. The proposed action does not include any unique or unusual activities that were not evaluated in the regional Multisale EISs and the Biological Opinion.

Shell‘s rigorous training program and standard operating procedures minimize the incidence of fuel and chemical spills. If a small fuel or chemical spill were to occur, it w ould be quickly contained and cleaned up in accordance with Shell‘s OSRP, as described in Initial EP Sections 2j and 9b.

A small fuel or chemical spill would disperse quickly, remain localized, occur intermittently, and not contain toxic constituents. For these reasons, a small fuel or chemical spill would not adversely affect the sperm whale. As described in Section 2.2.1 , the most common fuel spill is diesel, which remains the water‘s surface and dissipates rapidly (NOAA 2006).

A sperm whale exposed to diesel in the water could experience skin irritation, inflammation, or necrosis;

chemi cal burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [MMC] 2010). The small likeli hood of occurrence, the limited spatial extent of the project area, the temporary nature of a small fuel or chemical spill, and the ability of sperm whales to detect and avoid spill areas make it highly improbable that a sperm whale would actually be expos ed to a small spill. For these reasons, no significant adverse effects on the sperm whale would result from a small spill during the proposed action.

4.8.1.4 Impacts of a Large Oil Spill on the Sperm Whale

A blowout causing a large oil spill could have immediate direct and subsequent indirect adverse effects on the sperm whale. Immediate direct adverse effects would include exposure to the oil through dermal, ingestion, and inhalation pathways. Indirect ad verse effects of the spill could include ingestion of contaminated prey, interruption of foraging opportunities, and displacement from feeding areas (Geraci and St. Aubin 1987).

Dermal exposure to spilled oil could cause skin irritation, inflammation, ne crosis, and chemical burns. Whale skin is protected from dermal absorption by tight intercellular bridges, a thick epidermis, and the absence of sweat glands and hair follicles that would allow entry to subdermal layers. The epidermis of

whales effective ly excludes most constituents of petroleum (Geraci and St. Aubin 1985). Whales do not ingest oil while grooming or preening as do many other mammals and birds. However, they may ingest oil and dispersants incidentally while foraging and in contaminated p rey. Marine mammals are not particularly sensitive to ingested diesel or other petroleum compounds (Neff 1990).Whales may be exposed to toxic constituents in oil through inhalation, especially during the initial stages

of a large spill. Inhalation of pe troleum fumes could cause respiratory distress. Cetacean respiratory membranes are sensitive to hydrocarbon fumes, and toxic components of the oil can be absorbed by the bloodstream (Geraci and St. Aubin 1987).

Toxic effects of oil exposure through all pathways include impairment of the 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, reduced availab ility or quality of prey, interrupted reproductive behavior, and disturbance to typical patterns of movement or migration (MMC 2010).

In addition to impacts of the oil spill itself, the human response effort could also affect the sperm whale.

Increased v essel, helicopter, and fixed

- wing aircraft traffic would introduce additional noise and risk of vessel strikes. Response vessels would operate in accordance with NTL 2007

- G04 to reduce the potential for striking or disturbing marine mammals. Marine debri s in the form of containment materials could result in ingestion and entanglement problems. Use of dispersants could cause additional direct toxicity to the sperm whales or interrupt the food web that supports the whale (MMC 2010).

The likelihood of an y or all of these impacts actually occurring depends on the period of exposure, the condition of the individual whale before exposure, and the characteristics of the spilled oil. The most likely direct impact would be through the inhalation pathway, as th e whale‘s respiratory membranes are sensitive to hydrocarbon fumes, and toxic components of the oil can be absorbed by the bloodstream (Geraci and St. Aubin 1987). Interruption of the whale‘s foraging behavior, either by physical displacement or contamina tion, could occur, but is of less concern because the whales are highly mobile and extensive alternative foraging areas would be available ( BOEM 2011a).

Individual sperm whales could be adversely affected by a large oil spill under the proposed action. However, a large spill is extremely unlikely to occur because Shell has established rigorous well control and blowout prevention measures (see Initial EP S ection 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the

oil. Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, a lar ge spill is not likely to adversely the sperm whale.

4.8.1.5 Impacts of Vessel Strikes on the Sperm Whale

Vessel strikes are reported to threaten the recovery of the sperm whale. The most recent 5

- year status review reported that sperm whales continu e to be injured or killed by collisions with vessels. However, the incident rate and level of threat are low (NMFS 2009b).

Although a sperm whale is vulnerable to vessel strikes when it is ―rafting‖ at the surface for up to 10

- minute intervals between long dives (NMFS 2009b), it is not particularly susceptible to vessel strikes compared with other large whales. A study of 292 strikes of all large whales worldwide included only 17 collisions with sperm whales (13 mortalities) (Laist and others 2001, Jen sen and Silber 2004). Most collisions are with large vessels such as Navy ships, container and cargo ships, whale

- watching vessels, cruise ships, ferries, USCG vessels, and tankers (Jensen and Silber 2004). Large (more than 80 m) fast

moving (more than 1 4 knots) vessels pose the greatest risk of injury or death to the whales (Laist and

others 2001). USCG and NMFS regulations on marine mammal awareness and speed limits have reduced the incidence of vessel strikes in U.S. waters (NMFS 2009b).

The reactio n of a marine mammal to being struck by a vessel would depend on the severity of the collision. Minor strikes would cause temporary reversible effects, such as diverting the individual from its previous activity, causing transient pain, or separation from a group. Major strikes are those that can cause permanent injury or death. Apart from the severity of the physical strike, the likelihood and rate ofan individual‘s recovery from a strike may be influenced by its age, sex, reproductive state, and gener al

condition. Much of what is written about recovery from vessel strikes is inferred from observing individuals some time after the strike occurred. Numerous marine mammals bear scars that appear to have been caused by propeller cuts or collisions with v essel hulls. Conversely, fresh wounds such as propeller wounds on some stranded animals suggest a vessel strike as the cause of morbidity or mortality. Data from necropsies from dead stranded animals sometimes show massive internal injuries

consistent wi th ship strikes. The actual incidence of recovery versus death is not quantifiable, given

available data.

Support vessels under the proposed action are not of the class of ships that pose a substantial threat to large whales. Shell requires all support vessel operators to comply with protective measures instituted by

BOEM (NTL 2007

- G04), including training to identify marine mammals, maintaining watches for marine mammals, and avoiding collisions with marine mammals. Vessel operators are required to re port sightings of any injured or dead marine mammal. NTL 2007

- G04 provides guidance on avoiding whales, requiring operators to remain at least 300 feet (91 m) away from a whale when possible, and observe a

10

- knot speed limit near mother/calf pairs, pods, and other assemblages of large marine mammals when safety permits.

The Biological Opinion for the Five

- Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007

- G04 would reduce the likelihood of collisions between vessels and sperm whales to i nsignificant levels (NMFS 2007). The combination of sperm whales actively avoiding approaching vessels and operators actively avoiding

whales results in a low incidence of collision.

The proposed action 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. Shell‘s compliance with all mitigation and protect ive measures would reduce the potential for harassment of sperm whales to discountable levels (NMFS 2007). The proposed action is not likely to adversely affect the sperm whale.

4.8.2 Mysticete Whales

Five species of endangered mysticete whale (blue whale , fin whale, humpback whale, North Atlantic right whale, and sei whale) occur at least incidentally in the Gulf of Mexico but are considered rare or extralimital (Würsig and others 2000) ( Table 5 ).

These whales are so uncommon in th e Gulf of Mexico that NMFS did not include them in its Biological Opinion on the potential for oil and gas activities to adversely affect endangered marine mammals (NMFS 2007). Potential impacts to mysticetes were analyzed and found not to be significant in the regional Multisale EISs (MMS 2007b, 2008), which are incorporated by reference into this EIA. In the unlikely event that individual mysticete whales were present in the project area, expected impacts would be comparable to those described for the s perm whale in Section 4.8.1 . The geographic scope and limited duration of the proposed action make it extremely unlikely to result in any significant adverse effects on endangered mysticete whales.

4.8.3 West Indian Manatee

T he West Indian manatee includes two subspecies: the Florida manatee ( Trichechus manatus latirostris ) and the Antillean manatee ( T. m. manatus ). The entire species is federally listed as endangered, but only the Florida manatee occurs in the project area. The Florida manatee is depleted under the MMPA. Much of the general literature on manatees is not particular to one subspecies and is assumed to pertain to the Florida manatee. The West Indian manatee typically inhabits only coastal marine, brackish, and freshwater areas. Manatees occur in very shallow water depths 6.6 to 13.1 feet (2 to 4 meters) close to shore because of their preferred diet of sea grasses, which need high light levels to grow (FWS 2009c).During the winter, most Florida manatees rema in in warmwater refugia in peninsular Florida (FWS

2009c). In summer, individuals disperse northward up the Atlantic coast and westward into the Gulf of Mexico as far as Texas (Wilson 2003, Fertl and others 2005). Manatees could occur in the coastal wate rs of Louisiana only during the summer. They would never be expected to venture into the deep waters of the project area.

During the short time the manatee may occur in coastal Louisiana waters, the only IPFs potentially affecting it are associated wit h support vessel and helicopter movement near the onshore facilities and a large oil spill. Small fuel or chemical spills in the lease area are not considered IPFs for the manatee because this species does not occur in deep waters. A small spill would no t be transported from the project area to the shoreline 79 miles (127 km) away (NOAA 2006).

4.8.3.1 Baseline Conditions of the West Indian Manatee

The West Indian manatee is a rotund slow

- moving aquatic herbivorous mammal that can reach a

maximum length of 12.8 feet (3.9 m) ( Jefferson and others 2008) . It usually swims slowly (1 to 4 miles per hour [mph]; 1.6 to 6.4 kilometers per hour) but can sprint up to 15 mph (25 km/hr). When a manatee is at the surface, the only exposed parts are the tip of the muzzle and a small portion of the upper back, which makes it difficult to observe. The manatee makes short shallow dives, rarely descending deeper than 65 feet (20 m) or remaining submerged for more than 3 minutes. When resting at the bottom, a mana tee may stay submerged for up to 24 minutes (Department of the Navy 2008).

The manatee tends to swim alone or in groups of up to six ( Jefferson and others 2008)

.

The distribution, feeding habits, habitat use, and population estimates of manatees were des cribed in the Multisale EIS (MMS 2007b). The most recent available minimum population estimate of the Florida manatee is 1,822 animals (Waring and others 2009) . In 2011, the maximum number of Florida manatees was estimated at 4,834 (Florida Fish and Wild life Conservation Commission [FFWCC] 2011).

4.8.3.2 Impacts of Routine Activities on the Manatee

The Florida manatee would not be adversely affected by routine activities associated with the proposed action. Movement of support vessels and helicopters may disturb but not harass or injure individuals that are in coastal Louisiana waters during the summer. Helicopter flyovers could disturb manatees in the immediate vicinity. Helicopters contracted for the proposed action would maintain a minimum altitu de of

700 feet (213 m) during offshore transit, 1,000 feet (305 m) over unpopulated areas or across coastlines, and 2,000 feet (610 m) over populated areas and sensitive habitats such as wildlife refuges and park properties. Maintenance of minimum altitud es reduces the likelihood that manatees would be disturbed to less than significant levels.

No large congregation of manatees occurs in the coastal area near the heliport or seaport. As a coastal species, the manatee is exposed to background vessel noise . In fact, the manatee‘s lack of quick response to vessel noise accounts for its high injury rate from vessel strikes (see Section 4.8.3.4 ). However, the lack of response also suggests that noise generated by vessel movement and helicopter flyovers does not constitute a significant adverse effect to the Florida manatee.

4.8.3.3 Impacts of a Large Oil Spill on the Manatee

In a quantitative assessment of relative threats of human activity to the Florida manatee, vessel strikes

and loss of warm

- water habitats accounted for virtually all of the risk (Runge and others 2007). A large oil spill could affect the population, but t he chance that one will occur is exceeding small. The lease area is hundreds of miles from the population center of the Florida manatee in south Florida. Most manatees are on the east coast of Florida, beyond the range of a spill. Some manatees congrega te on the Gulf sideof peninsular Florida, especially in winter, but even this area is well outside the range of a reasonably

likely spill, given the rigorous response measures incorporated into the proposed action.

A small number of individual manatees i n coastal waters of the northern Gulf of Mexico could be affected by a large oil spill in several ways: direct exposure to oil and dispersants; loss of foraging habitat by oiling; and vessel strikes. Effects of direct exposure to oil and dispersants are n ot well known in the manatee, but are expected to be similar to those described for the sperm whale ( Section 4.8.1.4 ). The manatee may ingest more oil than the sperm whale because oil may accumulate on the shallow
vegeta tion that the manatee eats. The manatee also has sensory hairs around its mouth that could collect oil and interfere with feeding. If the oil and dispersants (or the physical disturbance of the response activity) resulted in injury to shallow vegetation, the manatee could experience loss of foraging habitat and subsequent nutritional deficiencies (FWS 2009c).

The manatee may suffer additional stress because of the intense human activity resulting from response and restoration in coastal areas ( BOEM 2011b ). The increase in vessel traffic responding to the spill in coastal waters and transiting to offshore waters puts the manatee at risk, especially because operators of the response vessels may not be as well

- trained as regular supply vessel operators in a voidance and protection measures for marine mammals.

The manatee could be indirectly affected if spilled oil (or dispersants) contaminated or killed the aquatic vegetation that it eats. These effects on the manatee from loss of forage would be minor an d temporary. The FWS estimated that up to 12 individual Florida manatees could be killed, in addition to natural mortalities, without causing serious population

- level effects (FWS 2009c). Based on the low density of manatees in coastal waters near the pr oject area and the unlikely occurrence of a blowout, the proposed action is not likely to adversely affect the Florida manatee.

4.8.3.4 Impacts of Vessel Strikes on the Manatee

The most significant threat to the Florida manatee is collision with vesse ls, including direct strikes and propeller cuts that can result in injury or death (FWS 2009c). Watercraft

- related incidents account for 25 to 35 percent of documented deaths (FWS 2010f).

The reaction of a manatee to being struck by a vessel would depend on the severity of the collision. Minor strikes would cause temporary reversible effects, such as diverting the individual from its previous activity, causing transient pain, or separation from a group. Major strikes are those that can cause permanent i njury or death. Apart from the severity of the physical strike, the likelihood and rate of an individual‘s recovery from a strike may be influenced by its age, sex, reproductive state, and general condition. Much of what is written about recovery from ve ssel strikes is inferred from observing individuals some time after the strike occurred. Numerous manatees bear scars that appear to have been caused by propeller cuts or collisions with vessel hulls. Conversely, fresh wounds such as propeller

wounds on some stranded animals suggest a vessel strike as the cause of morbidity or mortality. Data from necropsies from dead stranded animals sometimes show massive internal injuries consistent with ship strikes. The actual incidence of recovery versus death is not quantifiable, given available data.

Shell requires that contracted vessel operators comply with NTL 2007

- G04, which mandates training on detecting and avoiding marine mammals. One effective avoidance technique is to reduce vessel speed

when marine m ammals are present. Both manatees and boaters have time to avoid a collision at slower vessel speeds. If a collision occurs at slower speeds, the injury to the manatee is less severe (FFWCC 2007). Under routine conditions, supply vessels are not expecte d to strike manatees because operators are trained and committed to following the mitigation and conservation measures in BOEM ‘s NTL 2007

- G04 and other regulations of the MMPA. Vessel strikes under the proposed action are not likely to adversely affect th e Florida manatee.4.8.4 Non

- Endangered Marine Mammals

In addition to the seven endangered marine mammals discussed above, 22 other species of whales and dolphins potentially occur in the project area (see Initial EP Section 6h ) ( Table 9 ). These species are protected under the MMPA but are not listed as threatened or endangered under the ESA. Life history data, baseline conditions, and potential impacts of oil and gas activities were presented in the Multisale EIS (MMS 2007b), whi ch is incorporated by reference into this EIA. Impacts of the proposed action are

discussed below.

Table 9. Non

- endangered Marine Mammals in the Northern Gulf of Mexico

Non

- Endangered Marine Mammals Scientific Name Mysticete (Baleen) Whales Bryde‘s whale Balaenoptera edeni

Minke whale Balaenoptera acutorostrata Dwarf and Pygmy Sperm Whales Pygmy sperm whale Kogia breviceps

D warf sperm whale Kogia sima

Beaked Whales

Cuvier‘s beaked whale Ziphius cavirostris

Blainville‘s beaked whale Mesoplodon densirostris Sowerby‘s beaked whale Mesoplodon bidens

Gervais‘ beaked whale Mesoplodon europaeus Delphinids (dolphins)

Killer whale Orcinus orca

Short

- finned pilot whale Globicephala macrorhynchus

False killer whale Pseudorca crassidens Pygmy killer whale Feresa attenuata

Melon

- headed whale Peponocephala electra Rough

- toothed dolphin Steno bredanensis Risso‘s dolphin Grampus griseus Bottlenose dolphin Tursiops truncates Pantropical spotted dolphin Stenella attenuata Atlantic spotted dolphin Stenella frontalis Spinner dolphin Stenella longirostris Clymene dolphin Stenella clymene Striped dolphin Stenella coeruleoalba Fraser‘s dolphin Lagenodelphis hosei

4.8.4.1 Baseline Conditions of Non

- Endangered Marine Mammals

Mysticete whales

. Bryde‘s whale is the only large whale other than the sperm whale considered a common resident of the northern Gulf of Mexico. It is most often reported in shallow coastal waters along the 100

- m (328

- foot) isobath in the DeSoto Canyon region and to the e ast (Davis and Fargion 1996, Davis and others 2000). It is possible that individual Bryde‘s whales could occur in the lease area. The minke whale is considered rare in the Gulf of Mexico; the only confirmed records of this species in

the northern Gulf of Mexico are from stranded individuals (Würsig and others 2000).

Dwarf and pygmy sperm whales . The d warf sperm whale so closely resembles the pygmy sperm whale that the two species are generally referred to as ― Kogia spp.‖ Both species are known from theGulf of Mexico, primarily along the continental shelf edge and in deeper offshore waters (Mullin and

others 1991, Mullin 2007). Both of these species could occur in the project area.

Beaked whales . All four beaked whales known to occur in the Gulf of M exico could be present at the project site, as all are broadly distributed over the lower slope below 3,281 feet (1,000 m) and deeper (Davis and others 2000). Based on s tranding records, Gervais‘ beaked whale is the most common in the Gulf of Mexico, and Sowerby‘s beaked whale is the least likely to occur. None of the beaked whales is

common near the lease area.

Delphinids. The most common marine mammals in the deepwater Gulf of Mexico are the widely distributed dolphins (pantropical spotted, spinner, and clymene dolphins). However, any of the delphinids listed in Table 9 could occur in the lease area.

4.8.4.2 Impacts of Routine Activities on Non

- Endangered Marine Mammals

The evaluation of IPFs for the endangered sperm whale applies equally to non

- endangered marine mammals (see Section 4.8.1 ). Routine IPFs potentially affecting non

- endangered marine mammals include noise and lights and physica l disturbance of support vessels and helicopters. IPFs resulting from accidents include a small fuel or chemical spill, a large oil spill, and vessel strikes.

Neither permitted discharges nor marine debris is considered an IPF for marine mammals. Perm itted discharges from the drillship and support vessels would not pose any significant impact to non

endangered marine mammals because discharges would disperse quickly, remain localized, occur intermittently, and not contain toxic constituents (see Section 4.2.1 ). Shell‘s standard protocols for managing marine debris would minimize the potential for impacts to non

- endangered marine mammals, in compliance with NTL 2007

- G03.

The Multisale EIS (MMS 2007b) and site

- specifi c SEA S

- 7445 ( BOEM 2011b) evaluated potential impacts

to non

- endangered marine mammals. Neither noise and lights, nor the physical presence of the drillship and support vessels, were identified as IPFs for marine mammals in those documents, which are

inco rporated by reference into this EIA.

The proposed action would not introduce any new or unusual disturbance to the area. The drillship that would be used to drill the proposed wells works regularly in the deepwater Gulf of Mexico, moving from

site to sit e as needed. The proposed action would represent a minor increase in noise, lights, and physical disturbance to a limited spatial area. Based on the limited spatial area and temporary nature of

the disturbance in the context of the overall Gulf of Mexico environment, the routine IPFs associated with the proposed action would not significantly affect any non

- endangered marine mammals.

4.8.4.3 Impacts of a Large Oil Spill on Non

- Endangered Marine Mammals

Potential impacts of a large oil spill on non

- end angered marine mammals are comparable to those described for the sperm whale in Section 4.8.1.4 of this EIA and are consistent with conclusions reached in the Multisale EIS (MMS 2007b) and site

- specific SEA S

- 7445 ( BOEM 2 011b). The analysis of adverse effects of a large oil spill on the sperm whale included generalized data on other marine mammals and so is considered equally applicable to non

- endangered marine mammals. The proposed action does not include any activities that would cause unique impacts or a disproportionate effect on non

- endangered

marine mammals.

Marine mammals could be exposed to oil and dispersants via dermal absorption, ingestion, and inhalation, as described in Sec tion 4.8.1.4 for the sperm whale. Data are inadequate to evaluate the particular sensitivity of each species to oil or dispersants. Instead, it is assumed that toxicological effects data are generally applicable to other marine mammals (MMC 2010).Marine mammals are expected to react to the increased human activity associated with the response

action by avoiding disturbed areas. However, the specific behavioral reactions of each species are not

well known. The protective measures required by NTL 2 007

- G04 for endangered marine mammals would serve to reduce the potential for disturbing or striking other marine mammals as well. No significant adverse impacts would be expected.

The likelihood of significant impacts to any individual marine mammal dep ends on its period of exposure, its physiological condition, and the toxicity of the spilled oil. Inhalation is considered the most harmful pathway for most marine mammals because inhaled hydrocarbon fumes can deliver toxic constituents to

the bloodstream (Geraci and St. Aubin 1987). Interruption of the animal‘s foraging behavior, either by physical displacement or contamination, could occur; however, marine mammals are highly mobile, and extensive alternative foraging areas would be available (NMFS 2007, 2009a).

Individual marine mammals could be adversely affected by a large spill under the proposed action. However, a large spill is extremely unlikely to occur because Shell has rigorous well control and blowout prevention measures (see Initial EP Secti on 2j ). In the event that a blowout did occur, Shell‘s spill response measures would minimize the impacts by immediately containing and recovering the oil.

Initial EP Sections 2j and 9b provide detail on Shell‘s spill response plan. Therefore, no signif icant spill impacts on marine mammals are expected.

4.8.4.4 Impacts of Vessel Strikes on Non

- Endangered Marine Mammals

Vessel strikes are a recognized threat to marine mammals. The potential for non

- endangered marine mammals to be injured or killed by vessels associated with oil and gas activities was evaluated in the Multisale EIS (MMS 2007b) and the site

- specific SEA S

- 7445 ( BOEM 2011b). The analysis of the effects of vessel strikes on endangered marine mammals in the 2007 Biological Opinion can als o be extrapolated to the proposed action (NMFS 2007).

The reaction of a marine mammal to being struck by a vessel would depend on the severity of the collision. Minor strikes would cause temporary reversible effects, such as diverting the individual fr om its previous activity, causing transient pain, or separation from a group. Major strikes are those that can cause permanent injury or death. Apart from the severity of the physical strike, the likelihood and rate of an individual‘s recovery from a str ike may be influenced by its age, sex, reproductive state, and general condition. Much of what is written about recovery from vessel strikes is inferred from observing

individuals some time after the strike occurred. Numerous marine mammals bear scars th at appear to have been caused by propeller cuts or collisions with vessel hulls. Conversely, fresh wounds such as propeller wounds on some stranded animals suggest a vessel strike as the cause of morbidity or mortality. Data from necropsies from dead str anded animals sometimes show massive internal injuries consistent with ship strikes. The actual incidence of recovery versus death is not quantifiable, given

available data.

In comparison with other regions of the United States, the Gulf of Mexico is th e least common area for vessel strikes of large whales (Jensen and Silber 2004) . Between 1972 and 1999, eight confirmed or possible vessel strikes that involved large whales were recorded in the Gulf of Mexico, including two collisions with Navy vessels. Large whales may move too slowly to avoid vessels approaching at high speeds. Smaller species, such as dolphins, move more quickly and are less vulnerable to vessel strikes ( BOEM 2011a).

Support vessels under the proposed action are not of the class of ships that pose a substantial threat to large whales. Shell requires all support vessel operators to comply with protective measures instituted by

BOEM (NTL 2007

- G04), including training to identify marine mammals, maintaining watches for marine mammals, and avoiding collisions with marine mammals. Vessel operators are required to report sightings of any injured or dead marine mammal. NTL 2007

- G04 provides guidance on avoiding whales,requ iring operators to remain at least 300 feet (91 m) away from a whale when possible, and observe a

10

- knot speed limit near mother/calf pairs, pods, and other assemblages of large marine mammals when safety permits.

The Biological Opinion for the Five

- Ye ar Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico concluded that compliance with NTL 2007

- G04 would reduce the likelihood of collisions between vessels and sperm whales to insignificant levels (NMFS 2007). That conclusion can be reasonably applied to other large whales such as Byrde‘s whale.

The proposed action is not expected to result in any significant effect on migration, breathing, nursing, breeding, feeding, or sheltering to individuals, or have any cons equences at the population level. Shell‘s compliance with all mitigation and protective measures would reduce the potential for collisions with

marine mammals to non

- significant levels.

4.9 T hreatened and Endangered terrestrial Species and critical habit at

Coastal habitats in the northern Gulf of Mexico support protected species that could be affected by the proposed action. The diamondback terrapin (species of concern) and the federally

- endangered beach

mouse are discussed below.

4.9.1 Diamondback Terrapin (Species of Concern)

The diamondback terrapin ( Malaclemys terrapin ) is considered a species of concern by the FWS ( Federal Register 59, no. 219 [November 15, 1994: 58982 59028). The diamondback terrapin is the only North

American turtle that live s entirely in estuaries (Ernst and others 1994). Although this species was not considered in the programmatic EIS (MMS 2007b), impacts to the diamondback terrapin are included in the DWH event natural resource damage assessment, leading BOEM to add this s pecies to the 2011 SEIS for the Western Planning Area ( BOEM 2011a). No critical habitat has been designated for the diamondback terrapin, but it is known to inhabit open channels within coastal marshes (Dundee and Rossman 1989). The Texas diamondback ter rapin ( Malaclemys terrapin littoralis ) ranges along the coasts of Texas and Louisiana, and the Mississippi diamondback terrapin ( M. t. pileata ) occurs from Louisiana to Florida. Baseline conditions and potential impact discussions in the WPA SEIS ( BOEM 20 11a) are incorporated by reference.

The WPA SEIS concluded that the only IPF that could cause a significant long

- term adverse effect on the diamondback terrapin was a large oil spill. No collisions of service vessels with terrapins have been reported i n the Gulf of Mexico. Routine IPFs such as marine debris and vessel traffic were determined to cause less than significant impacts to this species ( BOEM 2011a).

The potential impacts of a large oil spill on diamondback terrapins were not considered in the Multisale EISs (MMS 2007b; MMS 2008). The OSRA modeling predicts that a large oil spill would not reach terrapin habitat within the first 10 days, but could contact the nearest Louisiana shoreline within 30 days. Terrapins in more distant coastal par ishes in Louisiana and to the east have a smaller but positive likelihood of being contacted by oil within 30 days of a large spill ( Table 4 ).

If oil from a large spill were to contact diamondback terrapins in their coastal habitat, individuals would likely experience decreased vigor, impaired reproductive success, and loss of immunity to disease, potentially leading to decreased lifespan ( BOEM 2011a). Adverse effects on hatchling terrapins would likely be more severe, poten tially leading to increased mortality. Baseline data on the diamondback terrapin are scarce, and the impacts of the DWH event on this species have not yet been quantified. However, the WPA SEIS reported that no impact to the diamondback terrapin has been reported during the more than 50 years the OCS program has been in existence ( BOEM 2011a). Because a large oil spill is a highly unlikely event, the probability that oil would enter the coastal channels frequented by the diamondback terrapin is very smal l. Shell‘s comprehensive OSRP is focused on quickly containing andcollecting spilled oil, which would limit the amount of oil that ultimately reached the coast. The proposed

action is not likely to adversely affect either subspecies of diamondback terra pin.

4.9.2 Beach Mouse

Four subspecies of a federally endangered beach mouse occur on barrier beaches in Alabama and Florida ( Table 10 ); critical habitat has been designated for all of them ( Figure 3 )

. Species descriptions and baseline conditions are described the Multisale EIS (MMS 2007b). The principal reasons for decline of beach mouse populations across the Gulf Coast are habitat destruction, habitat fragmentation, domestic or feral predators, and highway mortality. Natural threats include hurricanes and other large coastal storms, flooding, and erosion of coastal habitats (FWS 2009d).

Table 10. Federally

- Endangered Beach Mouse Subspecies on the Northern Gulf of Mexico

Coast

Coastal Animals Scientific Name

Alabama beach mouse Peromyscus polionotus ammobates
Choctawhatchee beach mouse P. p. allophrys Perdido Key beach mouse P. p. trissyllepsis

St. Andrew beach mouse P. p. peninsularis

The nearest beach mouse critical habitat is at least 120 miles (193 km) from the project area, outside the range of any routine IPFs. The only IPF that could adversely affect any of the beach mouse subspecies is a large spill that oiled substantial portio ns of their beachfront habitat.

The potential impacts of a large spill on any of the beach mouse populations are analyzed in regional EISs (MMS 2007b, 2008) and the site

- specific SEA S

- 7445 for a nearby lease ( BOEM 2011b). The proposed action would occu r in the OCS at least 120 miles (193 km) from the nearest critical habitat for the beach mouse. Based on the trajectory predicted by the OSRA modeling, oil would not reach beach mouse critical habitat within 30 days of a spill ( Table 4 ).

A large oil spill is an exceedingly unlikely event. However, significant adverse effects could result if a spill

were to occur and oil were to reach critical habitat for the beach mouse. Dermal contact with oil could irritate the skin, eyes, and m ucous membranes, leading to lesions and potential infection; mat the fur, making it difficult for the individual to groom itself and thermoregulate; and interfere with vision and hearing. Inhalation of petroleum fumes could cause breathing problems and to xicity, although the project site is far enough away that the oil would be weathered before it reached mouse habitat. Ingestion of oil and contaminated food could lead to intestinal blockages and subsequent starvation. Indirect impacts of exposure to oil via any of these pathways include reduction of the quantity or quality of food, degradation of habitat, and interruption of nesting or nursing. Direct physical impacts associated with the cleanup effort can also adversely affect the mice and degrade thei r habitat. The likelihood that oil would reach critical for the beach mouse is low because Shell‘s comprehensive OSRP is focused on quickly containing and collecting spilled oil and the project site is a great distance from the mouse‘s

critical habitat. The proposed action is not likely to adversely affect any of the subspecies of beach mouse or to modify or degrade any of their designated critical habitat.

4.10 Coastal Habitats and Protected Areas

The northern Gulf of Mexico coast is a complex mosaic of marine, brackish, and freshwater habitats, described in the regional Multisale and Supplemental EISs (MMS 2007b, 2008) as well as in the published literature. Shell‘s OSRP acknowledged the variety a nd vulnerability of coastal habitats and focused on methods for reducing impacts to these areas. In the central Gulf of Mexico, the distribution of coastal habitats is influenced primarily by the Mississippi River, which discharges tremendous volumes of f reshwater and sediment in a plume far out into the Gulf. West of the Mississippi River, the coast is

dominated by fine

- grained silts and muds supporting fragile marshes of varying salinities behind barrier islands that are in various states of degradatio n. East of the mouth of the river, the coast becomes

firmer as coarser

- grained sediments form true beaches protected by relatively intact barrier islands. Seagrass beds are rare to the west, but more abundant some distance east of the Mississippi River‘s heavy sediment load (Moncreiff 2007).

As mentioned in Section 4.5.3.7 , most of the coastal habitat in the northern Gulf of Mexico serves as EFH for a wide variety of species, including commercially and recreationally i mportant red drum, shrimp, and blue crab. In addition, 39 NWRs on the Gulf coast have a marine component and may be vulnerable to large oil spills. The NWRs occur across the coast, with 10 in Texas, seven in Louisiana, two in Mississippi,

and 20 in Flori da (FWS 2010g). The nearest NWRs to the project area are the Breton NWR and Delta NWR in Plaquemines Parish, Louisiana (Wilderness.net 2011).Figure 4. Distribution of Habitats in the Northern Gulf of Mexico4.10.1 Impacts o f Routine IPFs on Coastal Habitats

None of the routine IPFs would affect any coastal habitats because of the distance (79 miles [127 km]) of the project area from shore. The support bases at Port Fourchon and Amelia would continue to operate as they norma lly do, and no expansion would occur (see Initial EP Section 14 ). Support vessels work from established docks, travel in designated transit lanes, and maintain safe speeds in no

- wake zones, as required. Support vessels for the proposed action are comparable to vessels used for other oil and gas activities, offshore fis hing, and other offshore enterprises. Support vessels would not cause significant impacts to coastal habitats.

4.10.2 Impacts of a Large Oil Spill on Coastal Habitats

A blowout could release a substantial volume of oil in the Gulf, as described in Initial EP Section 2j

. Regional EISs analyzed the potential impacts of large oil spills on coastal habitats, including barrier beaches and dunes, wetlands, and submerged seagrass beds (MMS 2007b, 2008). The proposed action does not introduce any unique a ctivities that would cause additional impacts to coastal habitats.

The OSRA modeling results show that Plaquemines Parish, Louisiana, has the greatest chance (21 percent) of being affected by a large oil spill within 30 days. Several other coastal pari shes and counties to both the east and west of Plaquemines Parish have a greater than 1.0 percent probability that they would be contacted by spilled oil ( Table 4 ). The actual trajectory of the oil would depend in part on the prevail ing meteorological conditions at the time of the spill. A large oil spill is an extremely unlikely event, and implementation of Shell‘s OSRP would lead to immediate response action to contain and collect the oil. Nevertheless, some coastal habitats to th e northwest and northeast of the project area

could be affected. Numerous national and state wildlife refuges, parks, and other protected habitats occur in the region potentially affected by the oil, as discussed in the Multisale and Supplemental EISs (MM S 2007b, 2008) and Shell‘s OSRP. If the spill continued for more than 30 days, additional coastal parishes and counties could be affected.

Coastal habitat such as barrier beaches can be affected by freshly spilled oil and by weathered oil that

arrives o n shore many weeks or months after the spill. The characteristics of the oil that may appear on beaches would depend in part on the degree of weathering. Fresh oil is a buoyant liquid; oil mixed with water creates a mousse; and heavier, thicker component s form tarballs (MMS 2007b). Floating oil may be delivered to a beach in consecutive waves, leaving a high tide line much like a wrack line. Once oil is deposited on the beach, it may be worked into the sand, taken up by organisms, and further weathered. Over time, the lighter volatile components are released to the atmosphere and the viscous remnants commingle with sand and shell debris to form tarball conglomerates. Some heavy oil and tar may seep beneath the surficial sand and appear dormant, especia lly when temperatures drop; tar may liquefy and ooze to the surface again when the sand heats up in the summer. This cycle may repeat for several years until the oil is completely broken down by mechanical, chemical, or microbial processes (OSAT

- 2 2011; B OEM 2011a).

The length of the recovery cycle is influenced by the chemical nature of the oil and local weather conditions following the deposition. Although the lighter oils typical of the northern Gulf of Mexico are generally prone to degradation, the b reakdown products themselves can be toxic. An ongoing scientific debate regarding the effects of dispersants focuses on competing processes observed following the DWH event. By breaking up the oil slick, dispersants increase the surface to volume ratio, w hich promotes biodegradation (Atlas and Hazen 2011). However, dispersants may also retard the breakdown process by inhibiting bacterial metabolism (Hamdam and Fulmer 2011). Most research on dispersants assumed surface rather than subsea application. The r ole of light, nutrients, and oxygen in microbial digestion of oil is under active investigation (Hamdan and Fulmer 2011; Fox 2011; Atlas and Hazen 2011).

By some reports, efforts to remove oil from beaches may simply push the oil deeper below the surface. Mechanical removal may disturb sea turtle nests and sand

- dwelling organisms, damage plants, andfragment habitat in ways that increase rather than decrea se impacts (OSAT

- 2 2011; BOEM 2011a). The

ultimate impact to beaches would depend on the particular characteristics of the spill and the post

- spill

response.

Oil that is transported into vegetated wetland habitats is more damaging and difficult to remov e than oil that accumulates on beaches. Wetland plants are sensitive to both the oil and the physical disturbance associated with removing the oil. By some estimates, a 50

- bbl volume of oil in a coastal wetland would cause the temporary loss (die

- back) o f approximately 6.7 acres (2.7 hectares) of wetland vegetation. About a third of the damaged acreage would grow back during the first 4 years after the spill, and up to 85 percent would have recovered within 10 years. The remainder (15 percent) of the ve getation would die, leaving an area of permanently open water (MMS 2007b). The recovery estimates assume no additional oil spills or other serious impacts occur during that period. Louisiana wetlands have experienced great cumulative stress that makes th em less capable of recovering from significant events (MMS 2007b). Once a coastal marsh becomes fragmented by spatially intermittent diebacks, other forces such as storms can more easily break up the remaining acreage. The cumulative impacts of hurricane s and other stressors on marshes are discussed in Section 4.13.5

.

A large oil spill is an exceedingly unlikely event. Shell‘s approach to minimizing the risk of blowouts and large spills is discussed further in th e Initial EP Section 2j and 9b . Shell‘s OSRP includes training, policies, and protocols for preventing and minimizing spills. The specific containment and collection procedures would vary depending on the nature of the blowout, sea state, weather, and ot her prevailing conditions. Experts in various coastal habitats would be involved in identifying the appropriate protection, recovery, and cleanup techniques to use in each habitat, based on the extent of the spill, the characteristics of the oil, the seas on, the perceived vulnerability of various components of the ecosystem, and other factors. For all these reasons, no significant impact on coastal habitat is expected to result from the proposed action.

4.11 Archaeological Resources

Archaeological resou rces include both historic shipwrecks and prehistoric sites.

4.11.1 Shipwreck Sites

MC 525 is not in an area of high potential for historic shipwrecks, according to NTL 2005

- G07 and the most recent list of Archaeology Survey Blocks. The Archaeological Assessment conducted by C&C Technologies in 2009 reported 137 unidentified sonar contac ts and two debris zones located within the lease area. These sonar contacts were characteristic of modern debris primarily associated with industrial dumping or lease development activities. No shipwrecks were found within MC 525.

No historic shipwrecks are known to occur in the lease area. A small fuel or chemical spill would float briefly at the site and then dissipate quickly on the sea surface (NOAA 2006), without being transported to adjacent lease blocks where archaeological resources may occur.

The only potential IPF associated with the proposed action is a large spill that caused oil to be transported to adjacent lease blocks where archaeological resources occur. The BOEM requires an ROV survey of a 300

- m (984

- foot) radius around each wellsite because a severe subsurface blowout could resuspend and disperse sediments within that area (MMS 2007b). No shipwrecks occur within the area surveyed. The physical force of a blowout would not cause any direct impact to historic shipwrecks. If no dispersants are used to break up oil spilled in water, the oil typically rises to the surface and is then driven laterally by wind and surface currents and waves. Under those assumptions, a large oil spill would not likely affect archaeological site s on the bottom of the Gulf (MMS 2007a, 2008). The addition of dispersants, especially at depth, changes the behavior of the oil in ways that are not completely understood. Observations of the oil/dispersant mixture during the DWH event suggest that oil may contact shipwrecks at great depth. Subsurface plumes of oil/dispersant were reported as deep as3,600 feet (1,100 m) more than 22 miles (35 km) from the Macondo well for several weeks after the spill

(Camilli and others 2010, Joint Analysis Group 2010 c). Oil contacting waterlogged wood could promote fungal growth and accelerate the decay of the wood (Jurgens and Blanchette 2003). If dispersants were applied to a large oil spill, significant impacts to historical shipwrecks could occur.

Even without the use of dispersants, a large oil spill transported to shallow water could contact shipwrecks. The OSRA modeling predicts that shorelines from Louisiana to Florida could be contacted by a spill within 30 days, although at very low probabilities ( Table 4 ). Historic sites on or near shore, such as forts and lighthouses, could also be oiled, resulting in a temporary impact to visual aesthetics but no real harm to the structures (MMS 2007b). Once the oil was removed using safe proced ures, the historic structures would no longer be affected by the oil.

4.11.2 Prehistoric Archaeological Sites

Prehistoric archaeological sites are not expected to occur below 197 feet (60 m) in the northern Gulf of Mexico. The proposed project would be in water depths of 7,400 to 7,600 feet (2,255 to 2,316 m), well beyond the potential range. The only potential IPF for prehistoric sites is a large oil spill that was transported to coastal waters, which would have similar impacts to those described above f or historic shipwrecks. Numerous prehistoric sites are known on the barrier islands, mainland coast, and interior shores of bays and bayous all along the northern Gulf of Mexico (MMS 2007b), including areas that could receive oil that was transported to t he coast after a large offshore spill ( Table 4 ). Oil that reaches prehistoric sites could physically cover important artifacts, contaminate delicate materials, and interfere with radiocarbon dating (because the fresh organic hydrocar bons would yield a false signal of age). Although this type of oil contact can be cleaned, the removal process itself can physically damage fragile materials and settings of archaeological importance.

A large oil spill is exceedingly unlikely to occur or to cause any significant impact beyond the immediate project area. Shell‘s approach to minimizing the risk of blowouts and large spills is discussed further in

the Initial EP Section 9b. Shell‘s OSRP includes training, policies, and protocols for preven ting spills. The specific containment and collection procedures would vary depending on the nature of the blowout, location (nearshore or offshore), sea state, weather, and other immediate conditions. Impacts to shallow water shipwrecks or nearshore preh istoric sites are not expected to result from the proposed action.

4.12 Socioeconomic and Other Resources

Principal socioeconomic concerns in the northern Gulf of Mexico, aside from oil and gas production, include recreational and commercial fishing; non

- fishing recreation and tourism; and coastal employment and infrastructure. Other concerns addressed in this section include public health and safety, land use,

and other marine uses.

4.12.1 Recreational and Commercial Fishing

Recreational fishing in t he Gulf of Mexico is a $12 billion industry, including manufacturing, retail sales, charter operations, fishing guides, and license fees; sales of durable equipment accounted for most of the total. More than 100,000 jobs in the Gulf states were supported by the recreational fishing industry in 2008 (National Ocean Service [NOS] 2008). About 24 million recreational fishing trips were taken in the Gulf of Mexico in 2008, representing almost 30 percent of the national total (NOS 2008). Almost 50 percent of t he total recreational catch in the Gulf of Mexico was a single species, spotted seatrout ( Cynoscion nebulosus ). Other important recreational species include Atlantic croaker ( Micropogonius undulatus ), southern flounder ( Paralichthys lethostigma ), Gulf and southern kingfish ( Menticirrhus littoralis

), sand and silver seatrout ( Cynoscion arenarius and C. nothus ), red drum ( Scianops

ocellatus ), Spanish mackerel ( Scomberomorus maculatus ), striped mullet ( Mugil cephalus ), sheepshead ( Archosargus probatocephalus ) , and red snapper ( Lutjanus campechanus ). Most of these species arecaught in coastal waters and shallow bays, often associated with oyster beds, marsh vegetation, and tidal

inlets of state waters. The habitat function of platforms as artificial reefs is well

- known and forms the basis of the ―Rigs to Reefs‖ programs in the Gulf. However, offshore trips to oil and gas platforms make up a small percentage of recreational fishing excursions ( BOEM 2010b). No recreational or commercial fishing is allowed fro m the drillship or support vessels associated with the proposed action.

Commercial fishing ports in the northern Gulf of Mexico produced almost 1.3 billion pounds of fish and shellfish in 2008. The catch was worth more than $650 million; shellfish acco unting for more than 75 percent of the value (NMFS 2010d). Revenues for finfish and shellfish generally declined between 1999 and 2008 (NMFS 2010d). About 200,000 jobs are sustained by the commercial fishing industry across the five Gulf states (NMFS 201 0d). The top commercial species in the Gulf of Mexico are blue crab ( Callinectes sapidus

), mullet, stone crab ( Menippe mercenaria ), oyster ( Crassostrea virginica ), brown shrimp ( Farfantepenaeus aztecus ), white shrimp ( Litopenaeus setiferus ), groupers (Family Serranidae), red snapper, menhaden ( Brevoortia patronus ) , and tunas ( Thunnus spp.). Other than the tunas, these commercially important species occur in shallower waters shoreward of the project area.

The only commercial fishery active in the imm ediate project area is for tuna and swordfish by longlines. About 50 longline fishing vessels harvest yellowfin tuna and swordfish with an annual dockside value of $7 million (NMFS 2011b). Longlining occurs in the immediate project area as well as over a broad swath

of the northern Gulf of Mexico (Teo and Block 2010)

.

Routine IPFs associated with the proposed action would not affect commercial or recreational fishing, nor would a small fuel or chemical spill. However, a large oil spill could directly a ffect important fisheries species or lead to fisheries closures, which could result in economic impacts.

Impacts of a Large Oil Spill on Fishing

The impacts of an oil spill on the complex array of fisheries activities in the Gulf of Mexico has been analyzed in regional Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a). Nothing in the proposed action would change the conclusions of thos e EISs, which are incorporated by reference into this EIA. Depending on the time of year, the duration of the spill, the use of dispersants, and the prevailing meteorological conditions during and immediately after the spill, a substantial portion of the offshore waters of the northern Gulf of Mexico could be temporarily affected. More severe impacts to economically important fisheries species would be expected in areas where the oil enters shallower water

and reaches the shoreline. Extensive fisheries c losures after the DWH event caused some short

- term economic impacts. The closures covered 84,101 mi 2 (217,821 km 2 ), or about 35 percent of the U.S. EEZ in the Gulf of Mexico (NMFS 2010e), but did not necessarily cause permanent harm to any fisheries. In

fa ct, closures are widely used as management tools to create an opportunity for fisheries stocks to rebound, and are thought to have protected some spawning stocks following the DWH event (Fodrie and Heck 2011).

The DWH event in 2010 resulted from a unique series of events that is extremely unlikely to recur. In response to that event, Shell has joined with other entities to develop more rigorous and effective blowout prevention devices and procedures to minimize the likelihood of a similar large spill (se e Shell‘s

OSRP and Initial EP Sections 2j and 9b ). BOEM has implemented extensive programmatic reforms to enhance safety and ensure that operators are equipped to respond to accidents. Because of Shell‘s commitment to prevention and containment of spills , a large spill is not expected to cause significant long

- term adverse impacts on recreational or commercial fishing in the northern Gulf of Mexico.

4.12.2 Non

- Fishing Recreation and Tourism

The project area is not used for any recreational activities. N o routine IPFs associated with the proposed

action would affect recreation or tourism because the lease block is 79 miles (127 km) from shore. Shell complies with all waste disposal regulations, including NTL 2007

- G03, which minimizes the loss of debrisf rom the drillship and support vessels that might be deposited in coastal recreational or tourism sites.

Small fuel or chemical spills would be localized and short

- lived, as described in Section 4.2.2 (NOAA 2006). No significant impacts to non

- fishing recreation or tourism would occur.

A large oil spill could adversely affect non

- fishing recreation and tourism across the Gulf coast, as described in the regional Multisale and Supplemental EISs (MMS 2007b, 2008). The proposed acti on does not add any unique IPFs that would require a separate analysis of the impacts. The impacts on

recreation and tourism are similar to those described in Section 4.10.2 for coastal habitats. Most

recreation and touri sm on the Gulf coast are tied directly or indirectly to the Gulf itself or to the shoreline.

A blowout could release a substantial volume of oil into the Gulf that could contact and contaminate coastal recreational areas such as beaches, parks, and boat d ocks. Non

- fishing recreation centered on wetlands, such as duck hunting, could be affected by oil in coastal marshes (MMS 2007b 2008).

The most likely area to be contacted by spilled oil is Plaquemines Parish, Louisiana, according to the

OSRA model. Several other coastal parishes and counties both east and west of Plaquemines Parish have a greater than 1.0 percent probability that they would be contacted by oil after the spill ( Table 4 ). The actual trajectory of the oil would de pend in part on the prevailing meteorological conditions at the time of the spill. A large oil spill is an extremely unlikely event, and implementation of Shell‘s OSRP would lead to immediate response action to contain and collect the oil. Nevertheless, some coastal recreational

areas from Texas to Florida could be affected. Numerous national and state wildlife refuges, parks, and other recreational destinations occur in the region potentially affected by a large spill, as discussed in the

Multisale and Supplemental EISs (MMS 2007b, 2008) and Shell‘s OSRP. If the spill continued for more than 30 days, additional tourism and recreational locations in coastal parishes and counties could be

affected.

The duration of the impacts to tourism and recreation f rom a large oil spill is difficult to predict. During the DWH event, some recreation and tourism declined in locations where no oil contact occurred, or in advance of the oil‘s arrival. Media attention, uncertainty, and misinformation can cause people to cancel plans for recreation, leading to a cascade of loss of tourism revenue, including hotels, car rentals, restaurants, and retail sales.

Recreational areas and facilities on the coast may be affected by freshly spilled oil and by weathered oil

that ar rives onshore many weeks or months after the spill, as described in Section 4.10.2 for coastal habitats. The same processes and effects described as impacts to coastal habitats for wildlife are considered impacts to the hu man population using the oiled area.

Oil that is transported into vegetated wetland habitats is more damaging and difficult to remove than oil that accumulates on beaches, as described in Section 4.10.2 . Non

- fishing recr eation in coastal marshes, such as duck hunting, could be temporarily affected by actual or perceived degradation of the marsh. Hunters could go elsewhere to avoid the degraded areas or cancel their trips altogether. If the oiled areas suffer permanent l oss of vegetation, non

- fishing recreation also would decline (MMS 2007b).

A large oil spill is an exceedingly unlikely event. Shell‘s approach to minimizing the risk of blowouts and large spills is discussed further in the Initial EP Section 2j and 9b . Shell‘s OSRP includes training, policies, and protocols for preventing and minimizing spills. The specific containment and collection procedures would vary depending on the nature of the blowout, location, sea state, weather, and other prevailing condi tions. Experts in various coastal habitats would be involved in identifying the appropriate protection, recovery, and cleanup techniques to use in each habitat, based on the extent of the spill, characteristics of the oil, season, perceived vulnerability of various components of the ecosystem, and other factors. For all these reasons, no significant long

- term impact on recreation or tourism is expected to result from the proposed action.The immediate local economic effects on individual recreational or tourist facilities would be exacerbated

by larger

- scale regional problems with the image of the Gulf coast as a desirable tourist destination. Market studies conducted during and after the DWH event indicated that the public may be hesitant to accept tha t it is safe to swim and eat seafood caught in the Gulf of Mexico (Innovative Emergency Management, Inc. (IEM) 2010, Oxford Economics 2010; Gohlke and others 2011). The Gulf Coast was predicted to suffer economic losses of almost $23 billion during the 3 years after the DWH event, largely the result of diminished public interest in visiting there (Oxford Economics 2010). However, the regional recreational economy has recovered more quickly than expected. Hotels, restaurants, and recreational

facilities h ave reported full occupancy. In fact, the Mississippi's Gulf Coast reported that 2011 occupancy was the highest in 3 years (Myers 2011). Florida‘s 2011 coastal tourism business increased by 3.3 percent compared with the same pre

- spill period in 2010 (Mye rs 2011). In a recent SEA that evaluated exploratory activities similar to the proposed action, impacts to socioeconomic factors such as recreation and tourism were deemed negligible ( BOEM 2011b). Likewise, no significant long

- term irreversible

adverse im pact to recreation or tourism would result from the proposed action.

4.12.3 Coastal Employment and Infrastructure

The OCS oil and gas industry supports a wide variety of people who move among various projects as

needed. None of the routine IPFs associate d with the proposed action would directly affect employment or infrastructure. The supply and support vessels proposed for this project already exist and are serving other OCS projects in the area. The proposed action would use existing shore

- based facil ities in Louisiana and not require any expansion of infrastructure or increase in personnel. The project would have a negligible impact on employment and infrastructure. The project would not raise any concerns with environmental justice because it would not disproportionately affect minority or lower

- income

groups.

The only IPF associated with the proposed action that could significantly affect employment is a blowout that results in a large oil spill that interrupted the normal flow of work offshore. The potential socioeconomic impacts of a major spill are discussed in regional Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a). The proposed action does not include any unique or unusual activities that would change the assumptions or predi ctions of the regional EISs.

A large oil spill could cause major temporary direct and indirect economic impacts by interrupting the income flow of people who work in the oil and gas, commercial fishing, charter boat, and coastal tourism industries. Some individuals may be able to swi tch to short

- term work in support of the response effort, but this switch is not considered complete compensation for the loss of a person‘s chosen livelihood. People in coastal communities directly affected by a large spill would be directly impacted by lost income. In addition, people in communities beyond the reach of the oil spill may experience indirect economic impacts that require them to reevaluate their spending habits and change the way they allocate resources on both an individual and community level as income sources are diverted toward oil response and cleanup (Grattan and others 2011).

The severity of the economic losses would depend on the duration of the fishing closures and drilling suspensions; the extent of public hesitation in return ing to recreation and tourism in the area; and a variety of other unpredictable variables, such as decisions of individuals to return to former types of work after the spill.

The proposed action is extremely unlikely to result in a large oil spill. Shel l‘s well control and blowout prevention measures would minimize the probability of any significant long

- term impact on employment resulting from a spill. (See Initial EP Sections 2j and 9b for additional details on Shell‘s policies and procedures designed to protect against a blowout and accidental release of oil.) The combined effects of distance of the well sites from shore and Shell‘s rigorous OSRP support the conclusion that no significant impacts on employment or infrastructure would result from the proposed action.4.12.4 Public Health and Safety

The only people potentially exposed to routine IPFs associated with the proposed action are trained personnel who are performing specific tasks necessary to do their jobs. The public is not exposed to any

a ctivities that occur on the drillship. The supply vessels and helicopters are operated by licensed professionals who are contracted to fulfill certain functions and are not modes of public transportation. The drillship is more than 79 miles (127 km) from a point of public exposure. Vessel crews are trained and equipped to respond to small fuel or chemical spills and would not experience any ill effects. No routine activities or small spills would be expected to affect public health or safety.

In the u nlikely event that a blowout and large oil spill did occur, first responders could experience compromised safety and health for a short period of time (Levy and Nasetta 2011; Solomon and Janssen 2010). Shell‘s OSRP provides comprehensive plans for protect ing the people who are responsible for stemming the flow of oil and containing the oil that is released. Shell‘s OSRP meets or exceeds safety requirements set forth by USCG, EPA, the Occupational Safety and Health Administration (OSHA), and

the Internatio nal Convention for the Prevention of Pollution from Ships (MARPOL).

One of the principal goals of the first responders is to protect the health and safety of the public on shore by minimizing the amount of oil that arrives on the coast and the length of t ime it remains there. Shell‘s OSRP includes descriptions of several potential scenarios as guides, but the actual response methods would depend on the specific circumstances of the spill (flow rate, use of dispersants, characteristics of the oil, meteorol ogical conditions during and after the spill, whether the oil was burned [intentionally or accidentally], and other variables).

If liquid oil or smoke and fumes from burning oil reaches coastal communities, some people on the shoreline could be adversely affected (USCG 2009). Dermal exposure to oil could result from people walking through oiled areas and picking up oiled objects (including wildlife). People could be exposed via inhalation to volatile components of the oil as it weathers, to gases such a s methane released with the oil, and to smoke and fumes from burning oil. Finally, people may ingest oil either incidentally as they work around contaminated materials or as part of their food.

The National Instit ute for Occupational Safety and Health (NIOSH) evaluated the effects of human exposure to oil spilled during the DWH event. Although the final health hazard evaluation has not been released, some preliminary conclusions have been reported (Centers for Disease Control and Prevention [CDC] 2010a, b; Levy and Nasetta 2011). People exposed directly to oil while rescuing and cleaning wildlife reported symptoms consistent with dermal and inhalation exposure to oil, including red itchy skin,

head ache, lightheadedness, and fatigue. Crew members on vessels reported upper respiratory distress such as nose irritation, coughing, and sore throat. Headaches and heat

- related stress were also commonly reported.

Some indirect health

- related impacts on spill

- response workers were suspected but not confirmed, such as increased respiratory viruses caused by the close living quarters, respiratory irritation caused by dust and gravel at the docks, and second

- hand smoke (CDC 2010b). These symptoms are consist ent with health effects reported by people exposed to 38 other large oil spills worldwide (Levy and Nasetta 2011). In addition to the physiological symptoms experienced by response workers, people across the Gulf coast reported psychological effects stemm ing from lost income and security after the DWH event (Grattan and others 2011). Researchers predict that the long

- term impact of the DWH event and by extension, any large oil spill, will be the psychological stress of job loss and subsequent failure to co pe (Reardon 2011). The proposed action is in an area known where H 2 S concentrations have not been characterized. Unanticipated exposure to H 2 S could occur during a response action. During the DWH event, some response workers reported heat

- related stresses . If a large spill occurred during cooler months, both inhalation exposure and heat

- related stresses would likely be reduced, but hypothermia could pose a risk. A large oil spill is an extremely unlikely event. Shell‘s well control and blowout preventio n measures would minimize the probability of a large spill, as described in Initial EP Section 2j and 9b . Nosignificant impacts on public health or safety would result from the proposed action because the project

area is 79 miles (127 km) from the neares t shoreline where land use is an issue and Shell has committed to a rigorous OSRP focused on minimizing the chance of a blowout.

4.12.5 Land Use

Land use along the northern Gulf coast is determined largely by its function in the coastal economy. Support f

acilities for the offshore oil and gas industry are aggregated in Louisiana coastal parishes (notably Lafourche and Plaquemines). Often the same local areas, and even many of the same individuals, are committed to both the oil and gas and fisheries indust ries. The proposed action is typical of the type of project that supports existing land uses on the Louisiana coast where the supply bases are

located.

Regional Multilsale EISs analyzed the potential for deepwater oil and gas development to adversely a ffect land use and concluded that no impact was likely (MMS 2007b, 2008). No routine IPFs are expected to affect land use. Existing onshore industrial support facilities in Louisiana would be used, and no expansion of land

- based facilities would be requi red.

The only potential IPF affecting land use is large oil spill, which could produce temporary changes in land use in limited areas. For example, a major oil spill requires staging areas for the response team, expansion of parking and boat docking ar eas, additional disposal areas for cleanup wastes, temporary lodging for response personnel, and other short

- term localized adjustments to typical land use. The baseline land use would be restored as the number of people actively responding to the spill d ecreases over time. The only permanent change in land use could be additional disposal areas, but these areas are permitted by a separate municipal process that is independent of the proposed action.

Changes in land use are not expected to occur because a large oil spill is an extremely unlikely event. Shell‘s well control and blowout prevention measures would minimize the probability of a spill, as

described in Initial EP Section 2j and 9b . No signi ficant impacts on land use would result from the proposed action because the project area is 79 miles (127 km) from the nearest shoreline where land use is an issue and Shell has committed to a rigorous OSRP focused on minimizing the chance of a blowout.

4 .12.6 Other Marine Uses

The lease block (MC 525) is not in the ―Military Warning and Water Test Areas,‖ subject to NTL 2009

- G06 and is not typically used for military testing or training. Shell would comply with BOEM requirements and lease stipulations to avoid conflicts with military vessels and aircraft. No subsea wells or flowlines occur in the vicinity of the proposed wellsite locations. The DP drillship will not use anchors or mooring lines.

No routine IPFs associated with the proposed action woul d affect shipping or other marine uses. A large oil spill could cause a temporary interruption of shipping in the immediate area if a fire or other event made it unsafe for vessels to transit through the area. However, the lease is in a wide open area of the Gulf outside shipping lanes designated by the USCG; vessels would be expected to simply navigate around the site if necessary. In the event that a large aggregation of response vessels caused a navigational hazard, USCG would manage vessel traffic in a safe and orderly manner.

Shell does not anticipate any loss of well control that would lead to a large oil spill. Shell‘s blowout prevention technology and procedures would minimize the probability of a large spill, as described in

Initial EP Section 2j and 9b . No significant impacts on other marine uses would result from the proposed action because Shell has committed to a rigorous OSRP focused on minimizing the chance of a blowout and has highly trained personnel in place to respond to an accident at the site.Table 11. Summary of Effects of the Proposed Action on Protected and Managed Resources

Protected Resources Physical Presence of Drillship and Vessels (Noise/Lights) Water

Intake Effluent Air

Emissions Wastes Small Fuel or

Chemical Spill Vessel Strikes

(boats and helicopters) Large

Oil Spill Air Quality ○ ○ ○ ◊ ○ ◊ ○ ■ Water Quality ○ ○ ◊ ○ ○ ◊ ○ ■ Marine Species Deepwater Benthic

Communities ○ ○ ◊ ○ ○ ○ ○ ■

Lower Trophic

Levels ○ ○ ◊ ○ ○ ◊ ○ ■

Fish ◊ ◊ ◊ ○ ○ ◊ ◊ ■

Sea Turtles ◊ ○ ◊ ○ ○ ◊ ◊ ■
Birds ◊ ○ ○ ◊ ○ ◊ ◊ ■
Marine Mammals ◊ ○ ◊ ○ ○ ◊ ◊ ■
Coastal Species

Diamondback Terrapin ○ ○ ○ ○ ○ ◊ ○

○ ■

Beach Mouse ○ ○ ○ ○ ○ ◊ ○ ■
Coastal Habitats ○ ○ ○ ○ ○ ◊ ○ ■ Archeological Resources Shipwrecks ○ ○ ○ ○ ○ ○ ○ ■
Prehistoric Sites ○ ○ ○ ○ ○ ○ ○ ■
Socioeconomic Resources

Recreational and Commercial Fishing ◊ ○ ○ ○ ○ ◊ ○

○

○ ■

Non

- fishing

Recreation ○ ○ ○ ○ ○ ◊ ○ ■

Employment ○ ○ ○ ○ ○ ○ ○ ■
Land Use ○ ○ ○ ○ ○ ○ ○ ■
Other Marine Uses ○ ○ ○ ○ ○ ○ ○ ■ Note: The symbol in each cell represents the maximum potential effect level for the proposed action described in the text. Key :

○ No effect ◊ May affect, not likely to adversely affect ■ Likely to adversely affect4.13 Cumulative Impacts

Cumulative impacts are the additive consequences of the proposed action and other unrelated events reasonably expected to occur in the action area.

The U.S. Council on Environmental Quality defines ―cumulative effects‖ (also called ―cumulative imp acts‖ in NEPA documents) as follows: ―the impact on the environment which results from the incremental impact of the action when added to other past, present, and reasonably foreseeable future actions regardless of what agency (Federal or non

- federal) or p erson undertakes such other actions‖ (40 CFR 1508.7). The analysis of cumulative impacts in this EIA focuses on the incremental impact that the proposed action would (or could) have in combination with natural and anthropogenic stressors on important reso urces in the action area. Cumulative impacts can result from individually minor but collectively significant actions that take place over a period of time. Pre

- existing impacts of activities that have already occurred are not explicitly included in the c umulative impacts analysis, but are reflected in the descriptions of the affected environment ( Section 4.0 ). Impacts from prior activities that are still ongoing are considered current impacts and are discussed in this secti on. The cumulative impacts of the proposed action are the sum of previous, current, and proposed direct and indirect impacts of natural and human activities on a given resource.

The following types of cumulative impacts were examined with respect to the proposed action:

Additive effects, where individual effects from actions additively affect the same environmental

resources;

Countervailing effects, where the total cumulative effect is less than the sum of individual effects; or

Synergistic

, where the to tal cumulative effect is greater than the sum of the individual effects.

Given the uncertainties, complexities, and limited data availability associated with a large spill, the cumulative impacts of the proposed action cannot be quantitatively estimated. The discussion of cumulative impacts incorporates by reference the extensive analyses in the Multisale and Supplemental EISs (MMS 2007b, 2008; BOEM 2011a) and in the site

- specific SEA S

- 7445 ( BOEM 2011b) prepared after

the DWH event.

Before MC 525 was off ered for lease (in Lease Sale 205 on October 3, 2007), MMS prepared a programmatic EIS that analyzed the cumulative impacts of Lease Sale 205 in the context of other OCS and related activity (MMS 2007b). The proposed action is well

- represented by the rang e of activities analyzed in that EIS, as described below:

―environmental and socioeconomic impacts that may result from the incremental impact of the lease sales when added to all past, present, and reasonably foreseeable future human activities, includi

ng non

- OCS activities such as import tankering and commercial fishing, as well as all OCS activities (OCS Program). The OCS Program scenario includes all activities that are projected to occur from past, proposed, and future lease sales during the 40

- year analysis period (2007

- 2046). This includes projected activity from lease sales that have been held, including the most recent Lease Sale 200 (August 2006), but for which exploration or development has not yet begun or is continuing. In addition to human

ac tivities, impacts from natural occurrences, such as hurricanes, are analyzed."

Cumulative impacts were analyzed again in 2008 when MMS prepared an SEIS for additional lease blocks in the Central Planning Area (MMS 2008). The activities included in the proposed action clearly fall within the cumulative analysis presented in MMS (2007b).Activities described in the Initial EP were considered as part of the multiple lease sales along with impacts

related to fishing, hurricanes, and other events that could occur during the 40

- year leasing period (2007 to 2046) (MMS 2007b). Impacts associated with the lease sales included exploration (the current proposed action), as well as delineation and development wells and platforms. The cumulative impacts of support vessels, small fuel spills, and major oil spills were included in the regional analysis. The proposed action does not include any activity that would a lter the conclusions of the Multisale and Supplemental EISs.

The project area is in a region of the Gulf of Mexico with a history of extensive oil and gas exploration and development that can reasonably be expected to continue. Shell is conducting explo ration and development in adjacent and nearby areas, in accordance with BOEM regulations.

This EIA provides site

- specific information that allows a focused comparison of the proposed plan with the activities analyzed in the regional EISs. The Initial EP described activities that are consistent with activities described and evaluated in the Multisale EISs. This EIA incorporates details of the well locations and drillship and provides a calculated WCD based on methods prescribed in NTL 2010

- N06. The

anal ysis relies in part on new data collected since the DWH event, although much of the spill

- related data are not yet publicly available. Although the DWH event illustrated the ways in which a major oil spill

could affect various resources in the Gulf of Mex ico, it also elicited changes in the way the industry prepares for and prevents these accidents. Shell is better prepared to respond to a spill now than it was before the DWH event. Moreover, BOEM has provided comprehensive guidance to improve the safety of drilling in deep water. The combined efforts of BOEM and Shell have resulted in an unprecedented set of policies and procedures for preventing a blowout and minimizing an unplanned release from a well, as

described in Shell‘s Initial EP and OSRP. The net result of these efforts is that the proposed action would not significantly increase the cumulative impacts on any environmental, archaeological, or socioeconomic

resource.

Greenhouse Gases and Climate Change

GHG emissions occur from natural process es and human activities. The accumulation of greenhouse gases in the atmosphere regulates the earth‘s temperature and may contribute to global climate change, including rises in sea surface temperature, sea level, ocean acidification, and severe weather. Climate change may affect physical and biological resources in the project area in numerous ways, including loss of calcification of hard corals, increased vulnerability of coastal wetlands as sea level rises, and intensification of tropical storms and hur ricanes resulting from higher sea surface temperatures.

In the EIS for the Outer Continental Shelf Oil & Gas Leasing Program: 2007

- 2012 (MMS 2007a), the 2007 to 2012 leasing program was reported to make a negligible contribution to the global concentrations of GHG. However, since the programmatic EISs for the Central Planning Area were prepared in 2007, CEQ

and EPA have increased attenti on on the generation of GHG. Impacts of GHG on climate change are more commonly being included in NEPA analyses. Although not formally required by CEQ, federal courts have concluded that GHG emissions are ―a reasonably foreseeable consequence‖ of agency actions that must be included in NEPA analyses (Till and Brandt

- Erichsen 2010). Federal agencies are, on a national scale, addressing emissions of greenhouse gases by reductions mandated in federal laws and Executive Orders, most recently, Executive Order 13423.

EPA predicts that GHG emissions from most anthropogenic sources will continue to increase (EPA 2011c), but acknowledges that multiple unpredictable factors contribute to the rate of GHG production. The effects of increased GHG production are long

- term and complex. BOEM (2011a) estimated that relative sea level in the northern Gulf of Mexico will rise about 18 inches (45 cm) over the next 40 years, based on a rate of approximately 0.35 inch [9 mm]/yr. The change in sea level is partially attributed to subsidence (about 0.23 in [6 mm]/yr) and partially to climate change ( BOEM 2011a).Attention is now focused on the effects of acidification of the oceans, as excess atmospheric CO 2 is being

dissolved in the sea. Ocean acidification is considered a gl obal threat to marine ecosystems. Ocean acidification is the reduction of pH of seawater, which decreases the concentration of the carbonate ion in seawater. Coastal habitats are considered especially vulnerable to acidification, as they are expected to

e xperience both increases in sea temperature and decreases in pH (Teck and others 2010).

The potential effects of GHG emissions from the proposed action are by nature incremental. The incremental contribution of the proposed action is minimal as individua l sources of greenhouse gas emissions are not large enough alone to have an appreciable effect on climate change. Shell is committed to reduce the impacts of its operations on climate change by increasing the production of

clean

- burning natural gas, inves ting in sustainable biofuels; working on innovative methods for capturing and storing CO 2 emissions; and increasing the energy efficiency of its global operations (Shell 2011). In 2010, Shell met a voluntary target set in 1998 for direct greenhouse gas emissions from its facilities to be at least 5% lower than the comparable 1990 level (Shell 2011).

Other Cumulative Impacts

Cumulative i mpacts resulting from the following activities, unrelated to the proposed action, were analyzed in the WPA SEIS ( BOEM 2011a, Section 3.3), and are incorporated by reference:

 State oil and gas activity and pipeline infrastructure

 Other major factors Influen cing offshore environments

o Dredge material disposal

o OCS sand borrowing

o Marine transportation

o Military activities

o Artificial reefs and rigs

- to

- reefs development

o Offshore liquefied natural gas projects and deepwater ports

o Development of gas hydrates

o Renewabl e energy and alternative use

 Other major factors influencing coastal environments

o Sea

- level rise and subsidence

o Formation extraction and subsidence

o Mississippi River hydromodification

o Maintenance dredging and navigation channels

o Coastal restoration programs

o Coastal Impact Assistance Program

o Gulf Coast Ecosystem Restoration Task Force

 Natural events or processes

o Hurricanes

o Currents as transport agents

4.13.1 Cumulative Impacts to Air Quality

Cumulative impacts to air quality include emissions from bot h onshore and offshore sources. Onshore sources originate from power generation, industrial processing, manufacturing, refineries, commercial and home heating, and motor vehicles (MMS 2007b). Offshore emissions, which are dominated by marine vessels, hav e increased in recent years. In 1996, Compression

- Ignition (CI) marine engines were responsible for 7 percent of the total mobile source NO

x emissions in the United States, 6 percent of total

mobile source PM 2.5 emissions, and 21 percent of total mobile s ource SO 2 emissions. The EPA predicts that by 2030, marine engines will contribute 25 percent of mobile NO

x emissions, 25 percent of PM 2.5 emissions, and 81 percent of mobile SO 2 emissions (Fournier, 2006). In addition, shipping operations are responsibl e for 2.7 percent of global carbon dioxide CO 2 ) emissions. In the absence of policies to curb greenhouse gas (GHG) emissions, the International Maritime Organization (IMO)estimates by 2050 that

the CO 2 emissions may grow by a factor of 2 to 3 as a result of growth in shipping (IMO 2009).Recent federal short

- term NAAQS for NO 2 and SO 2 emissions may serve as countervailing impacts to

offset the increased emissions generated by coastal population growth. In general, activities associated with offshore explo ration in deep water are not considered to contribute significantly to air quality impacts (see Section 4.1 ) (MMS 2007b; BOEM 2011a). The proposed action would not contribute significantly to degradation of air quality in th e region.

4.13.2 Cumulative Impacts to Water Quality

Cumulative impacts to water quality are heavily influenced by onshore processes, especially urban runoff ( BOEM 2011a). Water quality may be degraded by suspended solids, heavy metals and pesticides, oil and grease, and nutrients, which are generally released in proportion to coastal population size. As the human population of the Gulf states continues to grow, u rban runoff is expected to increase (NOS 2008). Coastal and offshore water quality is also affected by agricultural runoff, municipal and industrial point sources, dredging and dredge disposal, and vessel

- related discharges.

The National Estuary Progra m‘s Coastal Condition Report (EPA 2007) reported that U.S. coastal waters are in ―fair to good‖ condition. More than half (57 percent) of the coastal areas were rated ―good‖ for water quality; about a third (34 percent) were rated ―fair,‖ and only 6 perce nt were considered ―poor.‖ Water quality has improved substantially overall since the initial survey in 2001, reflecting concerted efforts to reverse the degradation noted at that time. The Gulf Coast scored 3 out of 5 on overall water quality. The prin cipal cause of degraded water quality across all U.S. coasts is loss of water clarity (increased turbidity) and excess nutrients leading to increased chlorophyll a (EPA 2007).

Healthy aquatic and marine ecosystems are characterized by oxygen concentration s of at least 2 to 3 milligrams of oxygen per liter of water (mg/L). Some organisms require even higher levels of dissolved oxygen, up to 4.5 mg/L. Water with less than 2.0 mg/L dissolved oxygen is called ―hypoxic‖ (CENR 2010). The largest hypoxic zone currently affecting the United States, and the second largest hypoxic zone worldwide, occurs in the northern Gulf of Mexico adjacent to the Mississippi River on the Louisiana/Texas continental shelf. The hypoxic zone in the northern Gulf of Mexico from 20 04 to 2008 averaged about 6,563.7 mi 2 (17,000 km 2 ), about a third again as large as the surface area of the Chesapeake Bay and all its major tributaries (Louisiana Universities Marine Consortium [LUMCON] 2010)

. Hypoxic zones, often called ―dead zones,‖ sup port very little life other than bacteria.

Offshore waters in the lease area are not expected to be degraded by onshore pollutants to any great extent, but they are subject to increases in water temperature and acidification. The small amount of

dischar ge anticipated under the proposed action would add a negligible amount of turbidity to the immediate vicinity of the wellbore and would have no effect on hypoxia, turbidity, or nutrients. Based on data from the DWH event, even a large oil spill would not contribute substantially to the cumulative impacts of all activities on water quality in the Gulf of Mexico. The proposed action would not contribute significantly to water quality impacts in the region.

4.13.3 Cumulative Impacts to Marine Species and Hab itats

Cumulative impacts to deepwater benthic communities, lower trophic level organisms, fish and EFH, sea turtles, coastal and marine birds, and marine mammals are discussed below.

4.13.3.1 Cumulative Impacts to Deepwater Benthic Communities

Both chemosynthetic and nonchemosynthetic deepwater benthic communities are thought to be affected by global changes in ocean temperature and pH. As seawater becomes acidic, animals that use the carbonate ion to build hard structures, such as corals, exper ience a reduction or cessation of growth (Manzello 2010). Loss of structure

- forming coral reefs leads to a cascade of habitat degradation that threatens entire ecosystems (Lubchenco and Petes 2010). Additional threats to deepwater benthic

communities inc lude bottom trawling, carbonate mining, and hypoxia (Cordes and others 2009; CENR 2010). The proposed action would not contribute significantly to impacts on deepwater communities because it would not add substantially to GHG or physically impact extensive areas of deepwater habitat.4.13.3.2 Cumulative Impacts to Lower Trophic Levels

No human activities are reasonably expected to cause significant impacts to lower trophic level organisms

in the northern Gulf of Mexico. The area is so vast and well

- mixed that these planktonic communities are not at risk of local decline. Global sea temperature change and acidification could cause shifts in species assemblages over time, but no aspect of the proposed action would contribute to such changes.

4.13.3.3 Cumula tive Impacts to Fish, Fisheries, and EFH

Stressors on marine fishes that contribute to cumulative impacts in the northern Gulf of Mexico include overfishing, pollution, and nonnative species (discussed below). Climate change, aquaculture, energy productio n, and underwater noise are of concern globally but are of secondary importance in the project

area.

Overfishing is the most important threat that has led to the listing of ESA

- protected marine species (Kappel 2005; Crain and others 2009) with habitat l oss also contributing to extinction risk. Approximately 30 percent of the United States

- managed fishery stocks are overfished (NMFS 2009c). Overfishing occurs when fishes are harvested in quantities above a sustainable level.

Pollution primarily impact s coastal fishes that occur near the sources of urban runoff. However, global oceanic circulation patterns result in a considerable amount of marine pollutants and debris scattered throughout the open ocean (Crain and others 2009). Pollutants in the marine environment that may affect marine fishes include organic pollutants (such as pesticides, herbicides, polycyclic aromatic hydrocarbons, flame retardants, and oil), inorganic pollutants (for example, heavy metals), and debris (plastics and wastes from dump ing at sea) (Pew Oceans Commission 2003).

Fisheries managers in the Gulf of Mexico are concerned about the impacts of invasive species in the Gulf of Mexico. Lionfish ( Pterois volitans and P. miles ), native to the Pacific Ocean, are spreading rapidly

th roughout the Gulf of Mexico. These predaceous fishes were first observed at the Flower Garden Banks National Marine Sanctuary (FGBNMS) in summer 2011 and are expected to affect native invertebrates and fishes there as they have been reported to do in the southeast Atlantic (FGBNMS 2011). Another invasive species, the Australian spotted jellyfish ( Phyllorhiza punctata ), appeared by the thousands in the Gulf of Mexico in the summer of 2000 and again in 2003 (U. S. Geological Survey 2009). The biomass of je llyfish was so great that it clogged shrimp trawls, damaged the engine intakes on boats, and entangled fishing gear, resulting in the closure of otherwise productive fishing areas (USGS 2009). The jellyfish may also indirectly degrade commercial and recre ational fisheries by eating the larval fishes that form the prey base for economically important fishes. The proposed action would not contribute significantly to cumulative impacts on fish, fisheries, or essential fish habitat.

4.13.3.4 Cumulative Imp acts to Sea Turtles

Sea turtles are threatened both onshore during nesting and hatching and offshore as juveniles and adults. Two of the greatest threats to sea turtles in the ocean are ingestion of marine debris and collision with vessels. On land, by far the greatest adverse effect is loss of safe nesting sites. The cumulative effect of all human activity in the Gulf of Mexico on sea turtles is clearly negative ( BOEM 2011a). Although the problem of marine debris has been recognized, it is far from be ing solved. Likewise, vessel collisions continue to injure and kill sea turtles. Both marine debris and vessel traffic (commercial and recreational) are expected to increase. Some progress has been made in protecting nest sites on beaches, but mortality is still high. Even when beaches are legally protected, domestic and feral predators take a toll on hatchlings.

As human pressure on coastal habitats increases, natural habitats become less resilient and climactic events can pose disproportionate threat s. Storms can destroy turtle nests and tear out important sea grass beds where young turtles spend their growing years. Increase pollutants from the land continue to degrade coastal habitats essential to young turtles. The proposed action would not contr ibute significantly to cumulative impacts on sea turtles.4.13.3.5 Cumulative Impacts to Coastal and Marine Birds

The human migration to coastal counties is expected to continue, causing fragmentation and destruction

of sensitive coastal habitat. Criti cal wintering habitat for the piping plover on Gulf Coast beaches is under continuous pressure from incompatible recreational uses, including off

- road vehicles. Residential, commercial, and recreational developments adversely affect coastal and marine bir ds through habitat degradation, direct physical disturbance, and increased predation pressure by domestic and commensal

animals. Birds are at risk from strikes with aircraft and collisions with vehicles and from chemical

releases in coastal areas. Sea lev el rise threatens coastal nesting, foraging, and roosting habitat for the piping plover and other shorebirds. The combined impact of rising sea level and increasing storm intensity threatens to flood up to 85 percent of piping plover habitat (Seavey and ot hers 2011).

The cumulative effect on shorebirds, such as the piping plover, from strikes with aircraft is expected to rise proportionally to increases in the number of private and commercial aircraft operating along the coast. Recreational pressure on b eaches, foot traffic, off

- road vehicles, and noise disturbance will continue to adversely affect nesting, roosting, and foraging piping plovers and their critical habitat, wood storks, and roseate terns, leading to nest destruction, breeding and chick rear ing disturbances, and displacement of foraging areas. If disturbances exceed an unknown threshold of frequency, permanent displacement from preferred habitat or decreased reproductive success could occur. The proposed action would not contribute significa ntly to cumulative impacts on coastal or marine birds.

4.13.3.6 Cumulative Impacts to Marine Mammals

The cumulative effects of all human activity in the Gulf of Mexico on marine mammals are adverse. Vessel strikes are a constant threat, even with the e normous efforts expended by the USCG, NOAA, and advocacy groups to educate operators. Human impacts on marine mammals in the Gulf of Mexico include fisheries interactions (such as gear entanglement, shootings by fishermen, or bycatch [accidental

or indire ct catch]), ship strikes, noise and chemical pollution, and general habitat deterioration or destruction. Direct hunting is of great concern worldwide, but does not occur in the Gulf of Mexico. However, indirect captures of animals in fishing nets and ge ar (bycatch) may account for the deaths of more marine mammals than any other cause (Northridge 2008; Read 2008; Hamer and others 2010)

. Ship strikes are a growing issue for most marine mammals and may reduce the population of a species, particularly in s mall populations (Laist and others 2001). As international shipping increases and ships become faster and larger, whale strikes will undoubtedly continue to pose a significant threat.

Noise is of particular concern to marine mammals because it can cause b ehavioral disturbance, injury, and in some cases, may lead to death (Würsig and Richardson 2008; Tyack 2009) . Human

- caused noises in the marine environment come from shipping, seismic and geologic exploration, sonar, and other types of pulses produced by government, commercial, and private sources.

Chemical pollution is also of great concern, although for the most part, its effects on marine mammals are just starting to be understood (Reijnders and others 2008) . Recently, the 5.5

- year expedition of the Odyssey collected 955 biopsy samples from sperm whales around the world to provide a consistent

baseline database of ocean contamination that can be used to measure future effects (Ocean Alliance 2010) . Chemical pollutants and pesticides flow into the mar ine environment from human use on land and are absorbed into the bodies of marine mammals, accumulating in their blubber or transferring to the young via mothers‘ milk (Fair and others 2010)

.

Oil and other chemical spills are a specific type of ocean contamination known to have damaging effects on some marine mammal species (see Matkin and others 2008) , as described in Section 4.8.1.4 and

4.8.3.3 . Potential behavioral responses are displacement from primary habitat and the disruption of social structure, changes in prey availability and in feeding activities and success, effects on reproductive behavior, an d changes to migration. The proposed action would not contribute significantly to cumulative impacts on any species or stock of marine mammals.4.13.4 Cumulative Impacts to Coastal Species

4.13.4.1 Diamondback Terrapin

The diamondback terrapin is thre atened on land by some of the same human activities that threaten other coastal species, namely habitat destruction, road construction, and pollution. In addition, the terrapin faces dangers in the marine habitat, especially drowning in crab traps (Texas Parks and Wildlife Department 2011). Their coastal nesting areas have been degraded by beach erosion resulting from hurricanes and tropical storms. The diamondback terrapin is particularly vulnerable to habitat destruction

because it returns to the same ne st site year after year, has a low reproductive rate, limited survivorship, and a restricted home range ( BOEM 2011a). The regulations outlined in NTL 2007

- G04 (―Vessel

- Strike Avoidance‖) and NTL 2007

- G03 (―Marine Trash and Debris‖) serve to protect the dia mondback terrapin

from OCS

- related activity while it is in the water. However, neither Shell nor BOEM can reduce the major onshore threats to this species, which are the result of general coastal development. The proposed action would not contribute signi ficantly to cumulative impacts on the diamondback terrapin because the project would occur in the OCS far from the coastal waters that support the terrapin.

4.13.4.2 Beach Mouse

The principal threat to all of the subspecies of beach mouse is habitat los s and fragmentation caused by development of beachfront property. A secondary effect of converting dunes to residential developments is the introduction of the house cat and the house mouse ( Mus musculus ). House cats readily prey on beach mice, and the h ouse mouse competes with the native mice for food and burrow space. As natural populations of the beach mice become smaller and more isolated from one another, they becomes less able to recover from extreme events, such as hurricanes and floods (FWS 2009d ). The proposed action would not contribute significantly to cumulative impacts on any subspecies of beach mouse because the project area is so far away from the coastal habitats that support these animals.

4.13.5 Cumulative Impacts to Coastal and Marin e Habitats

Most coastal and marine habitats worldwide are under increasing pressure from human development and expansion (Butchart and others 2010) . Major stressors on most marine habitats are pollution, fishing practices, and global climate change (Pando lfi and others 2003; Lotze and others 2006) . Global climate change can alter sea level, ocean temperature, circulation patterns, precipitation patterns, air and ocean chemistry, and abundance and distribution of species (NOAA 2010) . The effects of these and other stressors may lead to the decline in the quality and distribution of marine habitats.

The rise in sea level could flood some habitats including salt marshes, which may have limited capacity to expand landward because of coastal development (Hoegh

- Guldberg and Bruno 2010; Nicholls and Cazenave 2010) . Human activities from coastal development that act on intertidal, salt marsh (Taylor 2008) , estuarine, and seagrass (Short and Wyllie

- Echeverria 1996) habitats include depositing fill material

f or development projects, disposing of dredge spoils, constructing aquaculture or salt ponds, and discharging waste products. Other stressors on salt marshes include encroaching invasive species and

subsidence (Barras and others 2003; Taylor 2008) . The in troduction of nonnative species can dramatically affect the community interactions within habitats. Of equal concern is the widespread diversion of the water and sediments that sustain mudflats throughout the coastal zone (EPA 2007). Seagrass is also neg atively affected by damage from boat propellers, increased sedimentation (particles settling on the seagrass) from dredging, and cloudy water from coastal development (Spalding and others 2003; Gulf of Mexico Program 2004) . Threats to sandy intertidal sho res include vehicle traffic (Lucrezi and others 2010)

, hurricanes, subsidence, and other erosive forces (for example, in Louisiana‘s barrier islands) (Barras and others 2003)

.

Coral reefs are under a variety of threats including coastal development (Field and others 2008) , impacts from inland pollution and erosion, disease, exploitative and destructive fishing practices, global climate change, and oil extraction (Hickerson and others 2008). Early life stages of coral are particularly sensitive to oil expo sure (Shafir and others 2007) . Once a species is made vulnerable by these human

- causedeffects, impacts from natural events such as storms can be magnified (Friedlander and others 2008,

2009) . Deepwater corals and hardbottom communities are threatened by heavy bottom trawls (Lumsden and others 2007; NOAA and U.S. Department of Commerce 2010) . As noted in the Multisale EIS, the incremental contribution of the proposed action to the cumulative impacts on regional resources is not significant (MMS 2007b).

4 .13.6 Cumulative Impacts to Archaeological Resources

Cumulative impacts to historic archaeological resources are generated by activities that disturb the seafloor, including exploration and development, dredging, anchoring, sand mining, deployment of

artif icial reefs, liquefied natural gas or other alternative energy development, and bottom trawling. Despite regulations enforced by BOEM that require pre

- project surveys for archaeological resources, some impacts likely occur because not every shipwreck or a rchaeological site is detected using current survey techniques ( BOEM 2011a). The limited spatial scale of the proposed action would not contribute to the cumulative impacts on archaeological resources because Shell has performed the required surveys

to do cument the absence of shipwrecks in the lease area.

4.13.7 Cumulative Impacts to Socioeconomic Resources

Cumulative impacts to socioeconomic conditions such as the commercial and recreational fishing industries, non

- fishing recreation and tourism, coast al employment, public health and safety, land use, and other marine uses are complex and difficult to quantify because they are mediated by numerous individuals making independent decisions. Variables such as the strength of the national and local

economi es, the price of energy, fluctuations in the domestic job market, and the occurrence of natural disasters influence socioeconomic conditions in the Gulf states. Most purposeful human activities in the Gulf of Mexico have a strong positive effect on socioe conomic conditions, but also pose some environmental risk that can have indirect adverse effects. The proposed action would contribute to either a positive or synergistic effect on socioeconomic conditions in the region.

5.0 Environmental Hazards

5.1 Geologic Hazards

The shallow hazards report states that the wellsites are free of any major geological hazards and are suitable for the proposed activities (C&C Technologies 2009). Initial EP Section 6a provides geological and geophysical data to support this conclusion.

5.2 Severe Weather

Severe weather short of a hurricane is not expected to pose any risk to the drillship or to interfere with the proposed action. The drillship and associated equipment were designed to operate for months at a

time in of

fshore locations exposed to high winds, strong currents, and oceanic waves. If severe weather threatens to interfere with safe operation of support vessels and helicopters, activities would be halted until conditions improved. Shell would follow the proc edures detailed in its Hurricane Evacuation Plan if

conditions warranted.

5.3 Currents and Waves

Wind speed and direction, sea states, and currents would be monitored throughout the drilling period. Drillships and associated equipment are designed to fun ction under both typical and extreme oceanographic conditions of the Gulf of Mexico, including storm

- generated waves, high winds, and subsea disturbances related to the loop current. Extreme weather such as hurricanes can disrupt drilling by making it uns afe for support vessels and helicopters to operate but is not considered a threat to the drillship or the well.6.0 Mitigation Measures

Mitigation measures that comply with laws, regulations, lease stipulations, and NTLs are considered an integral part of the proposed action. The project was designed to ensure compliance with all applicable and permitted pollution controls, including air emissions, discharges to water, and disposal of solid wastes. Shell‘s OSRP provides a framework for the overall project , including the activities in the Initial

EP Section 2j . Shell has obtained International Organization for Standardization (ISO) 14001 certification and continuously promotes pollution reduction. Shell is committed to adopting the mitigation

measures sho wn in Table 12 in addition to those required by 30 CFR 250:Table 12. Mitigation and Conservation Measures for Marine Species and Habitats

Type of Mitigation Purpose of Mitigation Measure

Reduce Collision / Physical Harassment

with Marine Mammals

and Sea Turtles Reduce Probability and Impact of Accidental Spill Reduce Impacts

to Fisheries, EFH,

and Sensitive

Habitats Reduce Routine

Pollution, including

Marine Debris Protect

Cultural

Resour ces Conduct pre

- tour and pre

- job safety meetings; daily reminders to all staff to maintain safety and minimize pollution at all times; discuss environmental consequences. √ √ √ √ √

Inspect and clean pollution pans on all tools arriving on the drillship; check plugs before tools leave the dock or are placed on a vessel. √ √ √

Inspect pollution pans and hydraulic lines and reservoirs on the drillship. √ √ √

Check direct overboard drains on the drillship regularly to verify plugs are installed. √ √ √

Place containment dikes around oil and drum storage areas, fuel vents, and fuel storage

tanks. √ √ √

Transport used oil and fuel to recycling

facilities on shore. √ √ √

Check direct overboard drains on the rig regularly to verify drain plugs are installed. √ √ √

Collect and secure solid waste daily; transport waste to shore for disposal or recycling by

vetted vendor. √ √

Inspect and change fuel hoses and SBM as appropriate. √ √ √

Use spill prevention fittings on liquid take

- on hoses as appropriate. √ √ √



### Dispose of unused paint by drying in the container and shipping to shore as waste. √ √ √

Use Envirorite hydraulic fluid on board. √ √Type of Mitigation Purpose of Mitigation Measure

Reduce Collision / Physical Harassment

with Marine Mammals

and Sea Turtles Reduce Probability and Impact of Accidental Spill Reduce Impacts

to Fisheries, EFH,

and Sensitive

Habitats Reduce Routine

Pollution, including

Marine Debris Protect

Cultural

Resour ces


### Use low sulfur fuel. √

Provide marine debris awareness and elimination training and information on initial employment and in an annual refresher. Verify training during rig orientation for new arrivals. (NTL 2007

- G03). √ √ √

Provide marine mammal observers during seismic operations. If warranted, provide observers during drilling operations NTL

2007

- G04). √

Support vessel operators reduce vessel speed

when marine mammals or sea turtles are in

the vicinity (NTL 2007

- G04). √

Maintain spatial buffer around sensitive benthic communities (NTL 2009

- G40). √

Require pilots to maintain recommended altitudes over sensitive habitats and species. √

Use drillship that complies with cooling

water intake provisions of GMG 290000. √

Comply with NPDES permitted effluent limits; complete daily NPDES reports. √ √

Maintain spatial buffer around archaeological resources (NTL 2005

- G07). √7.0 Consultation

No agency consultation on potential impacts of the proposed project was warranted.

8.0 Preparers

Tetra Tech, Inc. prepared this EIA under the direction of Shell. The following people contributed technical expertise to this document:

 Lori Downs (Environmental Team Leader, Shell Exploration & Production Co.);

 Rob Kuehn (Environmental Engineer, Shell Exploration & Production Co.);

 Jeff McMenis (Environmental Engineer, Shell Exploration & Production Co.);

 Tracy Albert (Regulatory Specialist, Offshore Technical Complia nce LLC);

 Sylvia Bellone (Regulatory Specialist, Shell Exploration & Production Co.);

 Randy Allen (Plans Specialist, Shell Exploration & Production Co.)

 Alec Bray (Team Leader

— Mesozoic, Shell Exploration & Production Co.);

 Christy Gibson (Staff Geologist, Shell Exploration & Production Co.);

 Hongbo Lu (Senior Geologist, Shell Exploration & Production Co.);

 Roger Van Noort (Senior Well Engineer, West Boreas and South Deimos Wells, Shell Exploration & Production Co.);

 June Mire, Ph.D. (NEPA Specialist and Pro ject Manager, Tetra Tech);

 Stephen Compton (Senior Project Manager, Tetra Tech);

 Kim Gorman (NEPA Specialist, Tetra Tech); and

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- 773 In W. F. Perrin, B. Wursig and J. G. M. Thewissen (eds.) Encyclopedia of Marine Mammals. San Diego, CA, Academic Press.

Yvon

- Lewis, S. A., L. Hu, and others (2011). Methane flux to the atmosphere from the Deepwater

Horizon oil disaster. Geophysical Research Letters 38.Appendix A

Matrix of Impact

- Producing Factors

and Environmental ResourcesEnvironmental Resources Potential 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

Vessels Accidents

Small Fuel Spill Large Oil

Spill

Physical/Chemical Environment Air quality and greenhouse gases

-- -- X

-- -- -- -- -- 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) Florida manatee (endangered)

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

-- X (6,8) Endangered mysticete whales

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

- endangered marine mammals (protected) X

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

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

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

-- -- -- -- -- -- -- -- -- X (6) Gulf sturgeon (threatened)

-- -- -- -- -- -- -- -- -- X (6) Beach mice (endangered)

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

Coastal and Marine Birds Marine and pelagic birds X

-- -- -- -- -- -- X X (6) X (6) Shorebirds and coastal nesting birds

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

-- X (6)

Fisheries Resources Pelagic communities and ichthyoplankton X

-- -- X X

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

Essential Fish Habitat X

-- -- X X

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

-- -- (7)

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

-- -- (7)

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

Coastal Habitats and Protected Areas

Beaches

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

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

-- 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)Notes:

X = potential impact

-- = negligible or no impact

(1) Activities that may affect a marine sanctuary or topographic feature. Specifically, if the well, platform site, or any anchors will be on the seafloor within the following: (a) 4

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

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

- m, 1

- mi, or 3

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

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

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

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

no

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

(2) Activities with any bottom disturbance within an OCS lease block protected throu gh 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 B ottom (Low

- Relief) Stipulation attached to an OCS lease.

 The Live Bottom (Low

- Relief) Stipulation is not applicable to the lease area.

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

 The proposed action will not impa ct high

- density deepwater benthic communities. No high

- density chemosynthetic communities or coral communities occur within 1,500 ft (457 m) of any drilling mud/cuttings discharge location.

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

 H 2 S has not been characterized in MC 525; concentrations of H 2 S are unknown.

(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.

 Impacts of a ccidental fuel or chemical spills could adversely affect the se resources. I mpacts are analyzed

in Section 4.0.

(7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated by

BOEM as having high

- probability for the occurrence of shipwrecks or prehistoric sites, i ncluding 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 EI A

can note that in a sentence or two.

 No known archaeological resources occur within the project area

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

sea turtles or their critical habi tats.

 Potential adverse effects on threatened and endangered species are analyzed in Section 4.0 within the section on each taxonomic group

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

 Not applicable.SECTION 19 : ADMINISTRATIVE INFORMATION

A. Exempted Information Description (Public Information Copies Only)

The following attachments were excluded from the public information copies of this plan:

Section 1b. OCS Plan Information form

– Bottom hole locations & proposed total depth

Section 2j. Blowout Scenario

– confidential information for NTL 2010

- N06 calculation

Section 3a. Geologic Description

Section 3b. Structure Contour Maps

Section 3c. Interpreted 2D or 3D seismic line(s)

Section 3d. Cross Section(s)

Section 3e. Shallow Hazards Report

Section 3f . Shallow Hazards Assessment

– confidential data

Section 3g. High

- Resolution Seismic Lines & Top Hole Progs

Section 3h. & 3i. Stratigraphic Column with Time vs. depth table

B. Bibliography

AUV Hazard study prepared by C&C Technologies, February 2009, Project #083926

- 084483, for Mississippi Canyon Blocks 479, 480, 481, 523, 524, 525, 567, 568, 569, 611, 612, and 613, for Mississippi Canyon 525, Proposed Locations A, B, C, D and E.

Previously filed Geohazards Assessment No. 2400

- 2040 for DeSoto Canyon Blocks 485 and 529 and Mississippi Canyon Blocks 525 and 569 prepared by Fugro Geoservices dated September 20, 2002, and Murphy E&P‘s previously submitted shallow haz ards report No. 2400

- 2070, prepared by Fugro Geoservices, for OCS

- G 19960, Mississippi Canyon 524 dated March 14, 2001 are also used for this EP.

Environmental Impact Analysis prepared by Tetra Tech, Inc., September 2011

Shell Offshore Inc. Regional Oil Spill Contingency Plan, August 2011