UNITED STATES GOVERNMENT MEMORANDUM

To: Public Information (MS 5030)

Plans Section, Office of Field Operations (MS 5231)

Public Information copy of Exploration Plan

Control # - S-07523

Type - Supplemental Exploration Plan

Lease(s) - OCS-G26254 Block - 393 Mississippi Canyon Area

Operator - Shell Offshore Inc.

Wells A, Q, Q(ST), R, S and T

SEMISUBMERSIBLE

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

should be addressed in an Environmental Assessment.

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

Michelle Griffitt

Plan Coordinator Description -

Rig Type - Subject: From: December 15, 2011Shell 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

November 2, 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: Supplemental Exploration Plan

OCS- G 26254

, Mississippi Canyon Block 393

Offshore Alabama and Louisia na

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. (S hell) requests your approval of this Supplemental Exploration Plan to drill Well Locations A, Q

, QST, R, S & T. Depending on rig availability operations could commence as early as May 2012.

This Plan consists of a series of attachments describing our intended operations. The attachments we desire to be exempted from disclosure under the Fr eedom of Information Act are marked “Confidential” and exclud ed from the Public Information copies of this submittal. The cost recovery fee receipt of $17,210.00 is attached to the Proprietary copy of the Plan.

Should you require additional information, please contact Tracy Albert at 504.728.4652 or tracy.albert@shell.com

.

Sincerely,

Sylvia A. Bellone

## SHELL OFFSHORE INC.

SUPPLEMENTAL EXPLORATION PLAN

for

OCS- G 26254
, Mississippi Canyon Block 393



# PUBLIC INFORMATION COPY

PREPARED BY:



## Tracy W. Albert Regulatory Specialist

504.728.4652

tracy.albert@shell.com

### REVISIONS TABLE:

Date of Request Plan Section What was Corrected Date Resubmitted

11/14/2011 Section 2J (Proprietary) Provided addtl. structure map (Proprietary) 11/17/2011SUPPLEMENTAL EXPLORATION PLAN

OCS- G 26254
, MISSISSIPPI CANYON BLOCK 393 OFFSHORE, ALABAMA AND 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 SPILL INFORMATION

SECTION 10 ENVIRONMENTAL 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 Ocean 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 barrels 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 Wildlife Management AreaSECTION 1: PLAN CONTENTS

A. DESCRIPTION, OBJECTIVES & SCHEDULE

Shell Offshore Inc. (Shell) is submitting a supplemental Exploration Plan (EP) for MC Block 393, OCS- G

26254. Shell submitted an Initial EP for this lease for subsea wells A through I in 2005. This Plan received an environmental site assessment (SEAE) from the BOEM due to its proximity to the Eastern Gulf of Mexico (Plan N-8379 approved July 18, 2005). Shell submitted a supplemental Plan for subsea wells J through P

, which also received SEAE (Plan S-7357 approved April 7, 2010). Shell is now submitting a Supplemental EP that includes six exploration wells: A (previously cleared in Plan N-8379) Q, QST, R, S & T. The wells will be drilled and temporarily abandoned with cement plugs and corrosion cap in accordance with 30 CFR 250.1721 until the wells are completed and developed under future plans. If the wells are unsuccessful, they will be permanently plugged and abandoned in accordance with BSEE regulations.

The drilling activities are planned to commence on or about May 1, 2012 and last approximately 1 00 days per well, except for the Q and QST, which are estimated to take approximately 107 and 62 days, respectively. The timeframe to complete the initial drilling activities is an estimate based on the best available information regarding downhole conditions likely to be encountered while drilling each well and are not intended to be a

limitation.

The lease area is 75 miles from the nearest shoreline, 1 62 miles from the onshore support base at Port Fourchon, Louisiana, and 100 miles from the helicopter base at Boothville, Louisiana. Water depths at the wellsites range from 7,300 ’ to 7, 39 0 ’ (Attachment 1 A)

.

The proposed rig is a moored semi-submersible, a self-contained drilling vessel with accommodations for a crew

which includ es quarters, galley and sanitation facilities. The rig will comply with the requirements in the Interim Final 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 SEP. Shell has employed or contracted with trained personnel 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 in 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 experience 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 393 drilling program. 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. In the unlikely event of a spill, Shell’s Regional OSRP is designed to contain and respond to a spill

that meets or exceeds the WCD as detailed in Section 9 of this SEP. 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 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 requirements. Shell will have trained personnel and monitoring programs in place to ensure such compliance.

B. LOCATION

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

C. RIG SAFETY AND POLLUTION FEATURES :

The rig planned for use

, Transocean Nautilus or similar, will comply with all of the regulations of the ABS, IMO and USCG. All drilling operations will be conducted under the provisions of 30 CFR, Part 250, Subpart 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 and seepage loss, and casing design will be our primary safety measures. Pollution prevention measures are as follows:DRAIN SYSTEM POLLUTION FEATURES

Drains are provided on the rig 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, rig washing, deck washing, and runoff from curbs and gutters, including drippans and work areas, are discharged depending on if it came into contact with the contaminated or noncontaminated areas of the rig.

1) Non-Contaminated Drains

Non-contaminated drains are designated as drains that do not contain hydrocarbons and can be discharged directly overboard. The salt water from the discharge of the fresh water makers and engine coolers is routed to the cuttings chute to provide a flush to keep the chute clear. All other non-contaminated drains are, where feasible, routed to the starboard caisson.

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 have to be collected in portable tanks and sent to shore for processing. Two headers are routed for the contaminated drains, one for oily water, which is routed to the separator tanks, and one for waste oil, which is routed to the waste oil tanks. In the areas where a spillage of oily water or hydrocarbon is possible, two foot valves are supplied, one for each header. The operator will make the decision on where to route the spillage. Separation and waste oil tanks are supplied in each of the aft columns. The headers in each of the decks are sealed from one another by using seal pots to prevent gas migration throughout the rig.

3) Mud Drain System

A separate drain system is furnished for the mud handling areas. Sumps are provided in the following areas to collect mud spills:

 Mud Pump Rooms

 Auxiliary Machinery Room

 Sack Storage Room

 Shale Shaker Room

The drains are pumped by two pneumatic mud drain pumps, which can route the drains either to overboard in the case of water-based muds, or to the main deck for collection into drums in the case of oil-based muds.

4) Oily Water Processing

The oily water is initially routed to the Separator Tanks. One tank is located in the 28.5 m flat in each of the aft columns. The tank has sufficient residence time to allow for natural separation of oil and water. The oil is manually drained to the Waste Oil Holding Tank located in the 28.5 m flat in each of the aft columns from where it is pumped to the International Shore Connection for collection into drums. The residual water in the separator is routed to the Oily Water Separator for further processing.

The Oily Water Separator is a compact, single stage, gravity-type vessel using a coalescer plate pack principle of separation. The oily water is drawn into the separator where the majority of the oil separates in the gravity stage below the oil chamber into which it rises and collects. The water pump draws the liquid through a multi-stage plate pack, which encourages the remaining oil droplets to coalesce and rise through the pack to the oil chamber. Clean water is drawn from the rear end of the unit by the water pump to an overboard discharge connection. Capacitance probes are fitted to detect the oil level in the oil chamber,controlling the pump to give fully automatic operation. A 15-ppm oil content meter is installed on the water

outlet to prevent oil discharges to the sea if any of the separation or monitoring systems should fail.

When oil/air covers the lower probe, the water pump stops, the oily water inlet valve closes, and the water inlet and oil/air discharge valves open to discharge the oil to the Waste Oil Holding Tank. When the top probe again senses water, the inlet oily water valve opens, the oil/air and water inlet valves close, and the pump again starts.

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

D. Storage Tanks - Transocean Nautilus (or similar)

T ype of Storage Tank Type of Facility Tank

Capacity (bbls) Number

of

Tanks Total

Capacity (bbls) Fluid

Gravity (API)

Diesel Tank in Pontoon Drilling Rig 2202 4 8808 Marine Diesel (0.87 SG)

Diesel Tank in Pontoon Drilling Rig 4554 4 18,216 Marine Diesel (0.87 SG) Diesel Day Tank 3 rd Deck Drilling Rig 196 2 392 Marine Diesel (0.87 SG) Diesel Settling Tank 3 rd

Deck Drilling Rig 225 1 225 Marine Diesel (0.87 SG) Diesel Settling Tank 3 rd

Deck Drilling Rig 271 1 271 Marine Diesel (0.87 SG)

Lube Oil Tank 3 r d Deck Drilling Rig 55 1 55 Lube Oil (0.93 SG)

Lube Oil Tank 3 rd Deck Drilling Rig 37 2 74 Lube Oil (0.93 SG) Hyd. Oil Tank 3 rd Deck Drilling Rig 55 1 55 Hydraulic Oil (0.93 SG)

E. Pollution Prevention Measures

Pursuant to NTL 2008-G04 the proposed operations covered by this SEP 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 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 inspect 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.

 Preventive 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, fuel 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 an annual basis.

 Spill prevention fittings are installed on all liquid take-on hoses.

 Shell has obtained ISO 14001 certification.

 Shell will use low-sulfur fuel to reduce air pollutant impacts.Attachment 1A

– Bathymetry and Surface LocationsAttachment 1B



### U.S. Department of the Interior OMB Control Number: 1010-0151 Minerals Management Service OMB Approval Expires: 12/31/2011
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 26254 Area: MC Block(s ): 393 Project Name (If Applicable): Corinth

Objective(s): X Oil Gas Sulphur Salt Onshore Base: Fourchon &

Boothville , LA Distance to Closest Land (Miles): 75

Description of Proposed Activities (Mark all that apply)

X Exploration drilling Developme nt 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

- design ated high

- probability archaeological area? X Yes No

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

* Well A approved 7/7/05 N

- 08379, ** Wells Q

- T requested in this plan. X

* Yes X

*

* No

Tentati ve Schedule of Proposed Activities

Proposed Activity Start Date End Date No. of Days

Drill well Q 05/01/2012 08/16/2012 107

Drill well Q Sidetrack 08/17/2012 10/18/2012 62

Drill well A 03/01/2013 06/09/2013 100

Drill well R 03/01/2014 06/09/2014 100

Drill well S 03/01/2015 06/09/2015 100

Drill well T 03/01/2016 06/09/2016 100

Description of Drilling Rig Description of Production Platform

Jackup Drillship Caisson Tension leg platform

Gorilla Jackup Platform rig Well protector Compliant towe r

X Semisubmersible Submersible Fixed platform Guyed tower

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

Drilling Rig Name (If Known): Transocean Nautilus or Similar Spar Other (Attach Description)

De scription 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 1C

OC S 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
(Previously cleared in Plan N

- 08379) Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Mississippi Canyon

Block No. 393 393

Blockline

Departu res (in feet) N/S Departure: 5

, 576 ’ FNL N/S Departure: 5

, 576 ’ FNL

E/W Departure: 1

, 868 ’ FEL E/W Departure: 1

, 868 ’ FEL

Lambert X

- Y

coordinates X: 1,344,532 X: 1,344,532

Y: 10,3 85,464 Y: 10,385,464

Latitude/
Longitude Latitude 28.6149 Latitude 28.6149

Longitude

- 87.9224 Longitude

- 87.9224

TVD (Feet): 25,100 ’ MD (Feet): 25,100 ’ Water Depth (Feet ): 7,385

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Paperwork Reduc tion 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 MM S 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 n ot 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 Explorati on Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direct comments

r egarding 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 1D 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): Q Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Mississippi Canyon

Blo ck No. 393 393

Blockline

Departures (in feet) N/S Departure: 5

, 451 ’ FNL N/S Departure: 4

, 777 ’ FNL

E/W Departure: 5

, 238 ’ FEL E/W Departure: 6

, 875 ’ FWL

Lambert X

- Y

coordinates X: 1,341,162 X: 1,33 7,435

Y: 10,385,589 Y: 10,386,263

Latitude/
Longitude Latitude : 28.6152 Latitude 28.6169

Longitude

– 87.9330 Longitude

- 87.9446

TVD (Feet): 25,841 ’ MD (Feet): 27,256 ’ Water Depth (Feet): 7,375 ’

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document
submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect p roprietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a perso n is not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Cont rol Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for pr eparing Exploration
Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g 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 Information Collection Clearance Officer, Mail Stop 423 0, 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 r enaming well or structure, reference previous name): Q ST Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Missi ssippi Canyon

Block No. 393 393

Blockline

Departures (in feet) N/S Departure: 5

, 451 ’ FNL N/S Departure: 5

, 904 ’ FNL

E/W Departure: 5

, 238 ’ FEL E/W Departure: 2

, 208 ’ FEL

Lambert X

- Y

coordinates X: 1,341,162 X: 1,344,1 92

Y: 10,385,589 Y: 10,385,136

Latitude/
Longitude Latitude 28.6152 Latitude 28.6140

Longitude

– 87.9330 Longitude

- 87.9235

TVD (Feet): 25,255 ’ MD (Feet): 26,390 ’ Water Depth (Feet): 7,375 ’

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

P aperwork 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

su bmitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect pro prietary data according to the Freedom of Information Act and 30 CFR 250.196. An agency may not conduct or sponsor, and a person i s not required to respond to, a collection of information unless it displays a currently valid Office of Management and Budget Cont rol Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for prepa ring Exploration
Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Dir ect comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 423 0, 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 re naming well or structure, reference previous name): R Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Mississip pi Canyon

Block No. 393 393

Blockline

Departures (in feet) N/S Departure: 6

, 617 ’ FSL N/S Departure: 6

, 617 ’ FSL

E/W Departure: 3

, 236 ’ FWL E/W Departure: 3

, 236 ’ FWL

Lambert X

- Y

coordinates X: 1,333,796 X: 1,33 3,796

Y: 10,381,817 Y: 10,381,817

Latitude/
Longitude Latitude 28.6046 Latitude 28.6046

Longitude

- 87.9558 Longitude

- 87.9558

TVD (Feet): 26,300 ’ MD (Feet): 26,300 ’ Water Depth (Feet): 7,311 ’

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Paperwork Reduction Act of 1995 Statement: The Paperwork Reduction Act of 1995 (44 U.S.C. Chapter 35) requires us to inform you that MMS collects this information as part of an applicant’s Exploration Plan or Development Operations Coordination Document
submitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect p roprietary 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 Cont rol
Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for pre paring Exploration
Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. D irect comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 423 0, 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 re naming well or structure, reference previous name): S Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Mississip pi Canyon

Block No. 393 393

Blockline

Departures (in feet) N/S Departure: 1

, 040 ’ FNL N/S Departure: 1

, 040 ’ FNL

E/W Departure: 3

, 640 ’ FWL E/W Departure: 3

, 640 ’ FWL

Lambert X

- Y

coordinates X: 1,334,200 X: 1,334,2 00

Y: 10,390,000 Y: 10,390,000

Latitude/
Longitude Latitude 28.6272 Latitude 28.6272

Longitude

- 87.9548 Longitude

- 87.9548

TVD (Feet): 26,450 ’ MD (Feet): 26,450 ’ Water Depth (Feet): 7,301 ’

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

Pa perwork 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

sub mitted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect prop rietary 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 Cont rol
Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for prepar ing Exploration
Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Dire ct comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 423 0, 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 w hich 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 renami ng well or structure, reference previous name): T Subsea Completion

Anchor Radius (if applicable) in feet: 15,500’ X Yes No

Surface Location Bottom

- Hole Location (For Wells)

Lease No. OCS

- G 26254 OCS

- G 26254

Area Name Mississippi Canyon Mississippi C anyon

Block No. 393 393

Blockline

Departures (in feet) N/S Departure: 5

, 045 ’ FNL N/S Departure: 5

, 045 ’ FNL

E/W Departure: 7

, 145 ’ FWL E/W Departure: 7

, 145 ’ FWL

Lambert X

- Y

coordinates X: 1,337,705 X: 1,337,705

Y: 10,385,995 Y: 10,385,995

Latitude/
Longitude Latitude 28.6329 Latitude 28.6329

Longitude

- 87.9438 Longitude

- 87.9438

TVD (Feet): 25,840 ’ MD (Feet): 25,840 ’ Water Depth (Feet): 7,358 ’

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

Anchor Name

or No. Area Block X Coordinate Y Coordinate Length of Anchor

Chain on Seafloor

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

X = Y =

XPap erwork 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

subm itted for MMS approval. We use the information to facilitate our review and data entry for OCS plans. We will protect propr ietary 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 Cont rol
Number. The use of this form is voluntary. The public reporting burden for this form is included in the burden for prepari ng Exploration
Plans and Development Operations Coordination Documents. We estimate that burden to average 580 hours per response, includin g the time for reviewing instructions, gathering and maintaining data, and completing and reviewing the form. Direc t comments regarding the burden estimate or any other aspect of this form to the Information Collection Clearance Officer, Mail Stop 423 0, 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 SEP as such information is only necessary in the case

of DOCDs.

D. Oil Characteristics

Information regarding oil characteristics is not included in this SEP 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 SEP.

F. Bonding

The bond requirement for the activities proposed in this SEP are satisfied by an area-wide bond furnished and maintained according to 30 CFR Part 256 , Subpart I-Bonding ; NTL No. 2000- G16

, “ Guideline for General Lease

Su rety Bonds” and National NTL No. 2008- N0 7 , “Supplemental Bond Proc ed ures.”

G. Oil Spill Financial Responsibility (OSFR)

Shell Offshore Inc.

, BOEM Operator Number 0689, has demonstrated oil spill financial responsibility for the wells proposed in the SEP ac cording to 30 CFR Parts 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 SEP as such information is only necessary in the case of DOCDs.J. Blowout scenario

Summary

This Section 2j was prepared by Shell pursuant to the guidance provided in the BOEM ’s NTL 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 and development to improve safety and reliability of our well systems. We are actively complying 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 OSRP, and detailed in EP Section 9a (ii), Shell has contracts with ORSOs to provide the resources necessary to respond to this WCD

scenario.

The WCD blowout scenario for Corinth is calculated for the MC-393 Q location near-crest penetration of the target sand and based on the guidelines outlined in NTL No. 2010-N06 along with subsequent Frequently Asked Questions (FAQ). Shell submitted MC 807 A as the worst-case 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 exceeds this WCD. This WCD does not take into account potential flow mitigating factors such as well bridging, obstructions in wellbore, reservoir barriers, and early intervention including containment capabilities.

Uncontrolled blowout (volume first day) 364,000 bbl

Uncontrolled blowout rate (first 30

- days average d aily rate) 353,000 bopd Duration of flow (days) based on relief well 128 days

Total volume of spill (bbls) for 128 days 44.9 MMBO

Table 2. 1 Worst Case Discharge Summary

The MC 393 project is located approximately 75 miles east-southeast of the nearest shoreline in the Gulf of Mexico (GOM), in water depths of approximately 7,375’ on MC -393. The structural component of the target is defined by a faulted nose approximately one mile long by three miles wide, with the top of the objective near

- 25,000’ sub sea (SS). The structure does not contain any previously drilled wells, but may have connected aquifer or hydrocarbons with the current (2011) well being drilled in MC-348. The only objective horizon with predicted flow potential is the target reservoir of Jurassic age.

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) enhance 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 the offset Appomattox (MC-392) and Vicksburg (DC-353) well data along with 3D seismic 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) BackgroundThis attachment has been developed to document the additional information requirements for EP’s 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 Requirements

a) Blowout scenario

Six locations in this submitted SEP were assessed for WCD. The MC-393 well from the Q location deviated near the crest of the structure represents the highest flow potential. The Q well will be drilled to the target reservoir as outlined in the Geological and Geophysical Information (Section 3) of the 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. 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/loss 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

- 393
Facility Designation MODU
Distance to Nearest Shoreline (miles) 75 Statute miles
Uncontrolled blowout (volume first day) 364,000 bbl
Uncontrolled blowout rate (first 30

- days average daily rate) 353,000 bopd

Table 2. 2 Estimated Flow Rates of a Potential Blowout

c) Total volume and maximum duration of the potential blowout

Duration of flow (days) 128 days total duration to drill relief well
(14 rig mob, 3 transit, 80 spud to top sand , 31 ranging).

Total volume of spill (bbls) 44.9 MMBO based on 128 days flowing.

Note : From MBAL/Prosper

Table 2. 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 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 of boundaries can cause the rate to drop continuously with production. Simulation and material balance

models can include these effects and form the basis of the NTL No. 2010-N06 estimates 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/collapse/bridge over within the span of a few days, significantly reducing the outflow rates. However, this WCD scenario does not include any bridging.

f) Likelihood for intervention to stop the blowout.Safety of operations is our top priority. Maintaining well control at all times to prevent a blowout is

the key focus of our operations. Our safe drilling record is based on our robust standards, conservative well design, prudent operations practices, competency of personnel, and strong HSE focus. 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 the Drilling Safety Rule with respect to Remotely Operated Vehicle (ROV) hot stab capabilities, a deadman system, and an auto shear system.

Additionally the Deepwater Nautilus (moored semi-submersible) has a gas handler system at the top of the riser consisting of two annular preventers that can be closed in to allow hydrocarbons in the riser to be contained or circulated thru the rig’s well control system. The rig has two shearing rams in the BOP for added redundancy. Also, the Nautilus is equipped with a deadman system and an auto shear 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 further analyzing these advances and incorporating them into its comprehensive approach to help prevent and, if needed, control another deepwater control incident.

Pursuant to NTL No. 2010-N10 Shell will provide additional information regarding our containment capabilities in a subsequent filing.

g) Availability of a rig to drill a relief 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 I and the Noble Bully I will be the preferred rigs for blowout intervention work. However, moored rigs can also be used in somescenarios. Additionally, in the event of a blowout, there is the distinct possibility that other noncontracted rigs in the GOM could be utilized whether for increased expediency or better suitability. All

efforts will be made at the time to secure t he appropriate rig. Shell’s current contracted rigs capable of operating at Corinth water depths and reservoir depths without constraints are in the following

table:

Rig Name Rig Type

Noble Danny Adkins dynamically positioned semisubmersible

Noble Globet rotter I * dynamically positioned drillship

Noble Bully I * dynamically positioned drillship

Deepwater Nautilus moored semisubmersible

Noble Jim Thompson moored semisubmersible

Table 2. 4 Shell Contracted Rigs Capable at Corinth.

Above are current as of October 2011. Future modifications may change the rig’s capability. Rig capabilities need to be assessed on a work scope specific basis.

* Globetrotter I & Bully I estimated arrival Q1 2012.

h) Time taken to contract a rig, move it onsite, and drill a relief wellRelief well operations will immediately take priority and displace any activity from Shell’s contracted

rig fleet. Table 2.4 above lists the Shell contracted rigs capable of operating at Corinth. 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 3 days transit to mobilize to the relief well site depending on distance to the site. The relief well will take approximately 80 days to drill down to the last casing string above the blowout zone, plus approximately 31 days for precision ranging activity to intersect the blowout well bore. Total time to drill a relief well would be ~128 days for the MC 393 wells.

If a moored rig is chosen to conduct the 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 deepwater 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 due to being over fifteen (15) miles to

the nearest structure.

i) Me asures 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 practices. The lessons learned from the investigation are, and will continue to be, incorporated into our operations.

Standards: Shell’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 standards 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 the systematic identification and mitigation process (Safety 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) to 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 significant depth and breadth of intern al drilling and 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 personnel 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 will meet all applicable rules, regulations, and Notices 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 Corinth. 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 aremonitored 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 returning 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 offshore drilling foremen and onshore 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 monitoring since 2003. Well site operations are monitored 24/7 virtually by onshore teams consisting of geoscientists, petrophysicists, well engineers, and 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 Foremen is practiced, which includes internal professional examinations to verify competency. Other industry training 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 programs. 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, audits), management HSE involvement and enforcement (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

sp ecific 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 dedicated 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

mo bilization 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.

As set forth in 2f of this document, Shell is currently analyzing recent advances in containment technology and equipment and will incorporate them as they become available.

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 active roles elsewhere. Resources from other operators can also be leveraged should the need arise. Generally, relief well plans will mirror theblowout well, incorporating any learning on well design based on root cause analysis of the blowout.

A generic relief 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 SEP as such information is not required by BOEM Gulf of Mexico Region.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:

Location A: AOA Geophysics, Inc. (2004), “Shallow Hazards Assessment MC393 (OCS G-26254), DC353 (OCS G-25852), DC354 (OCS G-23507), DC397 (OCS G-25853), AND DC398 (OCS G-25854) Mississippi Canyon and DeSoto Canyon Areas, Gulf of

M exico”, AOA Report No. 3038.3-SHL-DES, prepared for Shell Offshore Inc.

Fugro Geoservices, Inc (2007) Archaeological Assessment, Proposed Anchor Locations Block 393, Mississippi Canyon Area, Gulf of Mexico”, Fugro Report No. 2407 -1083, prepared for Shell Deepwater Development.

Locations Q, QST, R, S, T: Fugro Geoservices , Inc. (2011), “Shallow Hazards and Archa eological Assessment DeSoto Canyon Block 353 and Vicinity Appomattox Extension Project (OCS-G- 25852) Gulf of Mexico”, Fugro Report No. 2411-5001, prepared for Shell Exploration and Production Company

.

Fugro Geo Consulting, Inc. (2009), “Shallow Drilling H azards and Archaeological Assessment, Mississippi Canyon Blocks 347, 348, 391, 392 and Vicinity, Gulf of Mexico”, Fugro Report No. 27.2008-5022, prepared for Shell Exploration and Production Company.

F. Shallow Hazards Assessment

Proposed Location A, Mississippi Canyon 393 (Previously Approved):

For Proposed Location A, a review was made of the available geological and geophysical data within 985’ of

th e well site and to the surface casing depth of ~11,000’ MD (10,925 TVDSS). At the surface, there is no

ev idence of fault scarps, gas vents, hydrate mounds, unstable slopes, slumping, active mud gullies (crown cracks, collapsed depressions), furrows, sinkholes, surface channels, or reefs. There are no manmade hazards such as pipelines, wellheads, shipwrecks, ordnance, or communication cables. The Fugro 2007 report shows three wooden cylinders possibly covered by netting 674’ ESE of this proposed location. In the subsurface, there is no evidence of faults, gas-charged sediments, shallow-water flow, or buried channels.

The shallow stratigraphy at this location was described by AOA Geophysics. These units are different than the subsequent Fugro 2011 report. The Fugro units will be used with the AOA equivalents referenced in parentheses in this text (Attachment 3F with AOA nomenclature).

 Unit 1 from 7, 399’ -8, 803’ TVDSS (AOA Units 1, 2, and 3) consists of approximately 233’ of hemipelagic clays and mass transport complex deposits. 290’ of clays overlying mass transport complex deposits

, 263’ of channel overbank de posits associated with a large buriedchannel

, 263’ of clays, and 355’ of mass transport complex deposits with clays and overbank deposits.

 Unit 2 from 8,803 ’ -9,896 ’ TVDSS (AOA Unit 4) consists of 509’ of channel -margin and channel deposits overlying 584’ of mass transport complex deposits.

 Unit 3 from 9,896’

- 11,231’ TVDSS (AOA Unit 5) consists of 664’ of mass transport complex and possible channel deposits and 671’ of mass transport complex deposits with possible channel deposits

. A possible sheet sand is identified 3, 371’ below the mud line

.

 Unit 4 from 11,231’

- 13,155’ TVDSS (AOA below Unit 5) is are 793’ of interbedded mass transport complex and channel deposits overlying 1, 131’ of interbedded mass transport complex and channel deposits.

This location was selected to minimize the potential for shallow water flow. The potential for shallow water

flow is as follows:

 Unit 1 (AOA Geophysics Units 1-3) - Low

 Unit 2 (AOA Geophysics Unit 4) - Low

 Unit 3 (AOA Geophysics Unit 5) - Negligible

 Unit 4

– (AOA Geophysics below Unit 5) - Negligible

This location was selected to minimize the potential for encountering shallow gas. Potential for shallow gas is

as follows:

 Unit 1 (AOA Geophysics Units 1-3) - Negligible

 Unit 2 (AOA Geophysics Unit 4) - Negligible

 Unit 3 (AOA Geophysics Unit 5) - Negligible

 Unit 4

– (AOA Geophysics below Unit 5) - Negligible

This location was selected in order to avoid all identified amplitude anomalies. The closest amplitude anomalies to this location are approximately 1, 000’ northwest, 3 ,630 ’ to 6, 250’ below the mud line, and 1, 600’ northwest, 940’

to 3, 090’ below the mud line.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high-resolution data, this location appears suitable for the planned activity.

Proposed Location Q & QST, Mississippi Canyon 393:

For Proposed Location Q, a review was made of the available geological and geophysical data within 985’ of

th e well site and to the surface casing d epth of ~11,000’ MD (10,925 ’ TVDSS). At the surface, there is no evidence of fault scarps, gas vents, hydrate mounds, unstable slopes, slumping, active mud gullies (crown cracks, collapsed depressions), furrows, sinkholes, surface channels, or reefs. There are no manmade hazards such as pipelines, wellheads, shipwrecks, ordnance, communication cables, or debris, including thatcaused by hurricanes. In the subsurface, there is no evidence of faults, gas-charged sediments, shallowwater flow, or buried channels.

The shallow stratigraphy at this location is divided into 5 units (Attachment 3G ).

 Unit 1 from 7, 375’ -8, 784’ TVDSS consists of 110’ of hemipelagic drape over 300’ of mass transport deposits, over approximately 999’ of mass transport deposits, strat ified sediments and channelized deposits.

 Unit 2 from 8, 784’ -9, 944’ TVDSS consists of channel-levees deposited over rotated slides.

 Unit 3 from 9, 944’

- 11,360’ TVDSS consists predominately of clay with minor channels.

 Unit 4 from 11,360’

- 12,898’ TVDSS is identified as 1, 538’ of channel levee complexes.

 Unit 5 from 12,898’

- 17,222’ TVDSS is identified as 4

, 324’ of sands in mud and basin floor

sands. Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Low

 Unit 5 - Low

This location was selected in order to avoid all identified amplitude anomalies. Amplitude anomalies were identified in Units 1-5. The closest amplitude anomaly to this location is approximately 900’ north of this proposed location in Unit 3

.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high-resolution data, this location appears suitable for the planned activity.

Proposed Location S, Mississippi Canyon 393:

For Proposed Location S, a revie w was made of the available geological and geophysical data within 985’ of

th e well site and to the surface casing depth of ~11,000’ MD (10,925 TVDSS). At the surface, there is no evidence of fault scarps, gas vents, hydrate mounds, unstable slopes, slumping, active mud gullies (crown cracks, collapsed depressions), furrows, sinkholes, surface channels, or reefs. There are no manmade hazards such as pipelines, wellheads, shipwrecks, ordnance, communication cables, or debris, including thatcaused by hurricanes. In the subsurface, there is no evidence of faults, gas-charged sediments, shallowwater flow, or buried channels.

The shallow stratigraphy at this location is divided into 5 units (Attachment 3I ).

 Unit 1 from 7, 301’ -8, 581’ TVDSS consists of 110’ of hemipelagic drape over 300’ of mass transport deposits, over approximately 870’ of more mass transport deposits, stratified sediments and channelized deposits

 Unit 2 from 8, 581’ -9, 864’ TVDSS consists of channel-levees deposited over rotated slides.

 Unit 3 from 9, 864’

- 11,318’ TVDSS consists predominately of clay with minor channels.

 Unit 4 from 11,318’

- 12,812’ TVDSS is identified as 1

, 494 ’ of channel levee complexes.

 Unit 5 from 12,812’

- 17,314’ TVDSS is identified as 4 ,502 ’ of sands in mud and basin flo or sands.

This location was selected to minimize the potential for shallow water flow. The potential for shallow water

flow is as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Moderate

 Unit 5 - Low

This location was selected to minimize the potential for encountering shallow gas. Potential for shallow gas is

as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Low

 Unit 5 - Low

This location was selected in order to avoid all identified amplitude anomalies. Amplitude anomalies wer e identified in Units 1-5. The closest amplitude anomaly to this location is approximately 850 west of this proposed location in Unit 4

.Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s

with amplitudes applied and AUV high-resolution data, this location appears suitable for the planned activity.

Proposed Location T, Mississippi Canyon 393:

For Proposed Location T, a review was made of the available geological and geophysical data within 985’ of

th e well site and to the surface casing depth of ~11,000’ MD (10,925 TVDSS). At the surface, there is no evidence of fault scarps, gas vents, hydrate mounds, unstable slopes, slumping, active mud gullies (crown cracks, collapsed depressions), furrows, sinkholes, surface channels, or reefs. There are no manmade hazards such as pipelines, wellheads, shipwrecks, ordnance, communication cables, or debris, including thatcaused by hurricanes. In the subsurface, there is no evidence of faults, gas-charged sediments, shallowwater flow, or buried channels.

The shallow stratigraphy at this location is divided into 5 units (Attachment 3J ).

 Unit 1 from 7358’

- 8696’ TVDSS consists of 110’ of hemipelagic drape over 300’ of mass transport deposits, over approximately 928 ’ of more mass transport deposits, stratified sediments and channelized deposits

 Unit 2 from 8696’

- 9964’ TVDSS consists of channel-levees deposited over rotated slides.

 Unit 3 from 9964’

- 11,396’ TVDSS consists predominately of clay with minor channels.

 Unit 4 from 11,396’

- 12,885’ TVDSS is identified as 1489’ of channel levee complexes.

 Unit 5 from 12,885’

- 17,367’ TVDSS is identified as 4482’ of sands in mud and basin flo or sands.

This location was selected to minimize the potential for shallow water fl ow. The potential for shallow water

flow is as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Moderate

 Unit 5 - Low

This location was selected to minimize the potential for encountering shallow gas. Potential for shallow gas is

as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Low

 Unit 5 - Low

This location was selected in order to avoid all identified amplitude anomalies. Amplitude anomalies were identified in Units 1-5. The closest amplitude anomaly to this location is approximately 800 ’ west of this proposed location in Unit 3.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high-resolution data, this location appears suitable for the planned activity.

Shell will comply with NTL 2008-G05.

G. High-Resolution Seismic Lines

Proprietary data. The ESR Maps can be found in Section 6, Attachments 6A through 6E.This location was selected to minimize the potential for shallow water flow. The potential for shallow water

flow is as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Moderate

 Unit 5 - Low

This location was selected to minimize the potential for encountering shallow gas. Potential for shallow gas is

as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Low

 Unit 5 - Low

This location was selected in order to avoid all identified amplitude anomalies. Amplitude anomalies were identified in Units 1-5. The closest amplitude anomaly to this location is approximately 1, 000’ southeast of this proposed location in Unit 3.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high-resolution data, this location appears suitable for the planned activity.

Proposed Location R, Mississippi Canyon 393:

For Proposed Location R, a review was made of the available geological and geophysical data within 985’ of

th e well site and to the surface casing depth of ~11,000’ MD (10,925 TVDSS). At the surface, there is no evidence of fault scarps, gas vents, hydrate mounds, unstable slopes, slumping, active mud gullies (crown cracks, collapsed depressions), furrows, sinkholes, surface channels, or reefs. There are no manmade hazards such as pipelines, wellheads, shipwrecks, ordnance, communication cables, or debris, including thatcaused by hurricanes. In the subsurface, there is no evidence of faults, gas-charged sediments, shallowwater flow, or buried channels.

The shallow stratigraphy at this location is divided into 5 units (Attachment 3H ).

 Unit 1 from 7,31 1’ -8, 707’ TVDSS consists of 110’ of hemipelagic drape over 300’ of mass transport deposits, over approximately 986’ of more mass transport deposits, stratified sediments and channelized deposits.

 Unit 2 from 8, 707’ -10, 032’ TVDSS c onsists of channel-levees deposited over rotated slides.

 Unit 3 from 10,032’

- 11,464’ TVDSS c onsists of predominately clay with minor channels.

 Unit 4 from 11,464’

- 12,918’ TVDSS is identified as 1, 454’ of channel levee complexes.

 Unit 5 from 12,918’

- 17,555’ TVDSS is identified as 4, 637’ of sands in mud and basin floor

sands.

This location was selected to minimize the potential for shallow water flow. The potential for shallow water

flow is as follows:

 Unit 1 - Low

 Unit 2 - Low

 Unit 3 - Low

 Unit 4 - Moderate

 Unit 5 - Low

This location was selected to minimize the potential for encountering shallow gas. Potential for shallow gas is

as follows:H & I Stratigraphic Column with Time vs. depth table

Proprietary data

J. Geochemical Information

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

K. 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

10- 40 ppm.

B. Classification

Based on 30 CFR 250.490 (c) , Shell requests that the Regional Supervisor, Field Operations, classify the area in the proposed drilling operations as an area where H 2 S is known

.

C. H2S Contingency Plan

When the APD is submitted to BSEE, Shell will also include the H 2 S Contingency Plan prepared according to 30 CFR 250.490(f) before conducting the proposed exploration activities.

D. 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 SEP as such information is only necessary in

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

A. Chemosynthetic Communities Report

The following reports were used in this analysis:

Fug ro Geoservices, Inc. (2011), “Shallow Hazards and Archaeological Assessment DeSoto Canyon Block 353 and Vicinity Appomattox Extension Project (OCS-G 25852) Gulf of Mexico”, Fugro Report No. 2411

- 5001, prepared for Shell Exploration and Production Company.

Fugro GeoConsulting, Inc. (2009), “Shallow Drilling Hazards and Archaeological Assessment, Mississippi Canyon Blocks 347, 348, 391, 392 and Vicinity, Gulf of Mexico”, Fugro Report No. 27.2008 -5022, prepared for Shell Exploration and Production Company.

Fugro Geoservices, Inc (2007) Archaeological Assessment, Proposed Anchor Locations Block 393, Mississippi Canyon Area, Gulf of Mexico”, Fugro Report No. 2407 -1083, prepared for Shell Deepwater Development.

AOA Geophysics, Inc. (2004), “Shallow Hazards As sessment MC393 (OCS-G 26254), DC353 (OCS-G 25852), DC354 (OCS-G 23507), DC397 (OCS-G 25853), and DC398 (OCS-G 25854) Mississippi Canyon and DeSoto Canyon Areas, Gulf of Mexico”, AOA Report No. 3038.3 -SHL-DES, prepared for Shell Offshore

Inc.

Proposed Locat ion A and Generic 15,500’ Radial Anchor Pattern (Previously Approved)

There are no high-density deepwater benthic communities located within 2, 000’ of the proposed mud and cuttings discharge location.

There are no high-density deepwater benthic communit ies located within the 16,500’ anchor pattern. This is a generic 15,500’ anchor pattern plus an additional 1

, 000’ buffer area beyond the proposed maximum

anchor radius.

There is no evidence within this area of seafloor or near-surface hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, mounds, knolls, gas seeps, oil seeps, or hard bottom.

Currently, there are no flowlines or umbilicals within the 16,500’ radius of the proposed location.

Th is proposed location and associated anchor pattern will not interfere with identified seafloor sonar targets or with previously drilled well sites. There are 10 sonar targets and one previously drilled wellsite identified within the 16,500’ radius of the p roposed location. These are listed in the following table with the recommended avoidance distance. ROV Targets #1 and #2 are the only sonar targets identified
within 2000’ of this proposed location ( ROV#1 1780’ ESE with avoidance distance of 100’ and ROV#2 674’ ESE with avoidance distance of 200’).

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 high -resolution data, this proposed location appears suitable for the planned activity (Attachment 6A).Target From Location A Avoidance [ft] Target Description

ROV#1 1,780' ESE 100 Metal Barrel

ROV#2 674' ESE 200 Three wooden cylinders with netting

AUV#8 13,560' WNW 100 Modern Debris

AUV#9 13,097' NW 100 Amorphous

AUV#10 11,994' SW 500 Geologic

AUV#11 5,589' WNW 100 Modern Debris

AUV#12 12,371' SWS 100 Amorphous

Contact15 14,418' 100 Disturbed Seafloor

Contact19 16,382' 100 Modern Debris

Contact20 8,683' 100 Modern Debris

DC353 #1 7, 511 ESE 500 Drilled wellsite

- Shell Table 6.1. Targets within Proposed Anchor Radius.

Proposed Location Q & QST and Generic 15,500’ Radial Anchor Pattern

There are no high- density deepwater benthic communities located within 2000’ of the proposed mud a nd cuttings discharge location.

There are no high- density deepwater benthic communities located within the 16,500’ anchor pattern. This is a generic 15,500’ anchor pattern plus an additional 1000’ buffer area beyond the proposed maximum

anchor radius.

There is no evidence within this area of seafloor or near-surface hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, mounds, knolls, gas seeps, oil seeps, or hard bottom.

Currently, there a re no flowlines or umbilicals within the 16,500’ radius of the proposed location.

This proposed location and associated anchor pattern (including disturbances caused by anchors, anchor chains, wire ropes, and cables located on the seafloor prior to being pulled taut and attached to the MODU) will not interfere with identified seafloor sonar targets or with previously drilled well sites. There are eight sonar targets and two previously drilled wellsites identified within the 16,500’ radius of the proposed location. These are listed in the following table with the recommended avoidance distance. There are no seafloor sonar targets identified within 2, 000’ of the proposed location.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high -resolution data, this proposed location appears suitable for the planned activity (Attachment 6B ).Target From Location Q Avoidance [ft] Target Description

ROV#1 5,087' ESE 100 Metal Bar rel

ROV#2 3,975' ESE 200 Three wooden cylinders with netting

AUV#8 10,310' WNW 100 Modern Debris

AUV#9 10,975' NWN 100 Amorphous

AUV#10 10,030' SWS 500 Geologic

AUV#11 2,321' WNW 100 Modern Debris

AUV#12 11,933' S 100 Amorphous

Contact20 11,449' E 1 00 Modern Debris

DC353 #1 10,729' ESE 500 Drilled wellsite

- Shell

MC392 #1 14,385' SW 500 Drilled wellsite

- Anadarko Table 6.2. Targets within Proposed Anchor Radius.

Proposed Location R and Generic 15,500’ Radial Anchor Pattern

There are no high- de nsity deepwater benthic communities located within 2, 000’ of the proposed mud and cuttings discharge location.

There are no high- density deepwater benthic communities located within the 16,500’ anchor pattern. This is a generic 15,500’ anchor pattern plus an additional 1000’ buffer area beyond the proposed maximum

anchor radius.

There is no evidence within this area of seafloor or near-surface hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, mounds, knolls, gas seeps, oil seeps, or hard bottom.

Currently, there are no flowlines or umbilicals within the 16,500’ radius of the proposed location.

This proposed location and associated anchor pattern (including disturbances caused by anchors, anchor chains, wire ropes, and cables located on the seafloor prior to being pulled taut and attached to the MODU) will not interfere with identified seafloor sonar targets or with previously drilled well sites. There are eight sonar targets and three pr eviously drilled wellsites identified within the 16,500’ radius of the proposed location. These are listed in the following table with the recommended avoidance distance. There are no seafloor sonar targets identified within 2000’ of the proposed location.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high -resolution data, this proposed location appears suitable for the planned activity (Attachment 6C)Target Fr om Location R Avoidance [ft] Target Description

ROV#1 12,752' ENE 100 Metal Barrel

ROV#2 11,784' ENE 200 Three wooden cylinders with netting

AUV#6 12,546' W 100 Amorphous

AUV#8 7,655' NNW 100 Modern Debris

AUV#9 13,371' NNE 100 Amorphous

AUV#10 5,412 ' SSE 500 Geologic

AUV#11 7,072' NE 100 Modern Debris

AUV#12 10,768' SE 100 Amorphous

MC348#3 13,720' NW 500 Drilled wellsite

- Shell

MC392 #1 6,111' SW 500 Drilled wellsite

- Anadarko

MC392 #1 14,971' WNW 500 Drilled wellsite

- Shell

Table 6 .3 . Targets within Proposed Anchor Radius.

Proposed Location S and Generic 15,500’ Radial Anchor Pattern

There are no high- density deepwater benthic communities located within 2000’ of the proposed mud and cuttings discharge location.

There are no high-densit y deepwater benthic communities located within the 16,500’ anchor pattern. This is a generic 15,500’ anchor pattern plus an additional 1000’ buffer area beyond the proposed maximum

anchor radius.

There is no evidence within this area of seafloor or near-surface hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, mounds, knolls, gas seeps, oil seeps, or hard bottom.

There are flowlines and umbilicals associated with MC348 #1 and MC348 #2 app roximately 14,000’ to the northwest and within the 16,500’ radius of the proposed location. There will be a 500’ avoidance distance for anchors and associated equipment from these flowlines and umbilicals.

This proposed location and associated anchor pattern (including disturbances caused by anchors, anchor chains, wire ropes, and cables located on the seafloor prior to being pulled taut and attached to the MODU) will not interfere with identified seafloor sonar targets or with previously drilled well sites. There are eight sonar targets and five previously drilled wellsites identified within the 16,500’ radius of the proposed location. These are listed in the following table with the recommended avoidance distance. There are no seafloor sonar targets identified within 2, 000’ of the proposed location.

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high -resolution data, this proposed location appears suitable for the planned activity (Attachment 6D).Target From Location S Avoidance [ft] Target Description

ROV#1 13,062' SE 100 Metal Barrel

ROV#2 11,952' SE 200 Three wooden cylinders with netting

AUV#6 15,031' SW 100 Amorphous

AUV#7 14,958' NNW 100 Modern Debris

AUV#8 2,870' WSW 100 Modern Debris

AUV#9 5,259' NNE 100 Amorphous

AUV#10 13,214' SSE 500 Geologic

AUV#11 5,951' SE 100 Modern Debris

MC348 #1 14,103' NW 500 Drilled wellsite

- Marathon

MC348 #2 15,109' NW 500 Drilled wellsite

- Marathon

MC348#3 9,16 1' W 500 Drilled wellsite

- Shell

MC392 #1 12,333' SW 500 Drilled wellsite

- Anadarko

MC392 #1 14,720' WSW 500 Drilled wellsite

- Shell

Table 6 .4 . Targets within Proposed Anchor Radius.

Proposed Location T and Generic 15,500’ Radial Anchor Pattern

There are no high- density deepwater benthic communities located within 2000’ of the proposed mud and cuttings discharge location.

There are no high- density deepwater benthic communities located within the 16,500’ anchor pattern. This is a generic 15,500’ anchor pattern plus an additional 1000’ buffer area beyond the proposed maximum

anchor radius.

There is no evidence within this area of seafloor or near-surface hydrocarbon-charged sediments associated with surface faulting, acoustic void zones associated with surface faulting, mounds, knolls, gas seeps, oil seeps, or hard bottom.

Currently, there are no flowlines or umbilicals within the 16,500’ radius of the proposed location.

This proposed location and associated anchor pattern (including disturbances caused by anchors, anchor chains, wire ropes, and cables located on the seafloor prior to being pulled taut and attached to the MODU) will not interfere with identified seafloor sonar targets or with previously drilled well sites. There are eight sonar ta rgets and three previously drilled wellsites identified within the 16,500’ radius of the proposed location. These are listed in the following table with the recommended avoidance distance. AUV Sonar Target #11 is the only sonar target identified within 200 0’ of this proposed location (1,456’ ENE with avoidance distance of 100’).

Based on a high-resolution geophysical survey, consisting of frequency enhanced 3- D seismic, ESR’s, ESR’s with amplitudes applied and AUV high -resolution data, this proposed location appears suitable for the planned activity (Attachment 6E).Target From Location T Avoidance [ft] Target Description

ROV#1 8,567' ESE 100 Metal Barrel

ROV#2 7,456' ESE 200 Three wooden cylinders with netting

AUV#8 6,968' NW 100 Modern Debris

AUV #9 9,304' NNW 100 Amorphous

AUV#10 9,210' SWS 500 Geologic

AUV#11 1,456' ENE 100 Modern Debris

AUV#12 12,724' SSE 100 Amorphous

DC353 #1 14,170' E 500 Drilled wellsite

- Shell

MC348#3 13,970' NW 500 Drilled wellsite

- Shell

MC392 #1 11,628' SW 500 D rilled wellsite

- Anadarko

Table 6 .5 Targets within Proposed Anchor Radius

B - F

Pursuant to NTL No. 2008-G04 the proposed operations covered by this SEP 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 Block 393 is located in Grid 17. Grid 17 is an area that does not have adequate ROV survey coverage; therefore we will run the pre- and post-ROV survey in accordance with NTL 2008

- G0 6

.

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 and physical observations will be documented using Form MMS-141. Complete documentation, including videotapes, of both surveys will be submitted to the BOEM within 60 days of the final survey.

H. Threatened and Endangered Species Information

There are 5 species of sea turtles that may be found in the Gulf of Mexico (see Table 6. 6 below). No critical habitat for these species has been designated in the Gulf of Mexico.

Common Name Scientif ic 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 T

Table 6. 6

–

Threatened and Endangered Sea Turtles There are 29 species of marine mammals that may be found in the Gulf of Mexico (see Table 6. 7 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
Bry de'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 Globicep hala 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

Table 6. 7

–

Threatened and Endangered Marine Mammals

Section 18 discusses potential impacts and mitigation measures related to threatened and endangered species.

I. Archaeological Report

The following reports were used in this analysis:

Fugro Geoservices, Inc (2007) Archaeological Assessment, Proposed Anchor Locations Block 393, Mississippi Canyon Area, Gulf of Mexico”, Fugro Report No. 2407 -1083, prepared for Shell Deepwater Development.

Fugro GeoConsulting, Inc. (2009), “Shallow Drilling Hazards and Archaeological Ass essment, Mississippi Canyon Blocks 347, 348, 391, 392 and Vicinity, Gulf of Mexico”, Fugro Report No. 27.2008-5022, prepared for Shell Exploration and Production Company

.

Fugro Geoservices, Inc. (2011), “Shallow Hazards and Archaeological Assessment DeSo to Canyon Block 353 and Vicinity Appomattox Extension Project (OCS-G- 25852) Gulf of Mexico”, Fugro Report No. 2411-5001, prepared for Shell Exploration and Production Company.Archaeological Analysis

Fugro (2007) performed a high-resolution geophysical survey over three proposed anchor locations within Block 393, in order to evaluate for evidence of shipwrecks. They identified two sonar contacts (ROV#1, ROV#2). The first contact is a cylindrical metal object, interpreted as a drum, and therefore is probable modern debris. The second contact is partially buried, and has the appearance of being three wooden cylindrical objects, with possible netting draped over them. Both contacts should be avoided. There were no other unusual depressions, scours, sediment changes, or unidentified seafloor targets observed that could represent unidentified shipwreck remains.

Fugro (2009) performed a high resolution geophysical survey, identifying twelve sonar contacts. Sonar contacts 1, 2, and 10 are all small isolated features that are likely geologic in origin. Sonar contacts 7, 8, and 11 are isolated linear features that are interpreted as probable modern debris. The remaining six contacts are classified as unidentified amorphous objects. None of the twelve sonar contacts are interpreted as archaeologically significant. There are no other unusual depressions, scours, sediment changes, or unidentified seafloor targets observed within the survey area that could represent unidentified shipwreck

remains.

Fugro (2011) performed a survey extension to the 2009 high resolution geophysical survey identifying 37 sonar contacts. A majority of the sonar targets observed are fairly small in size and measure less than 25’ in length and width. Contacts Nos. 1-14 and 16-20 appear as hard contacts, likely representing man-made debris. Contacts Nos. 15 and 25-37 appear geologic in origin. Sonar contact No. 19 is at the terminus of an anchor drag scar. The drag scar runs in a north- south direction and is within 10,000’ of the DC353 #1 well

lo cation. The drag scar and associated contact are interpreted to be the result of prior construction activities. No unusual depressions, scours, sediment changes, or unidentified seafloor targets were observed that could represent unidentified shipwreck remains.

Shell will comply with all conditions of NTL 2008-G 20

.

J. Air and Water Quality Information

Pursuant to NTL 2008- G04 the proposed operations covered by this SEP do not require Shell to provide additional information relating to air and water quality information. For specific information relating to air and water quality information please refer to Section 18

.

K. Socioeconomic Information

Pursuant to NTL 2008- G04 the proposed operations covered by this SEP 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 in this Plan

.SECTION 7: WASTE AND DISCHARGE INFORMATION

A. Projected Ocean DischargesB. Projected Generated Wastes

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 (where 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 sets 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 (ton s) Calculated

Complex Total

Emission

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

Note: AQR Worksheets are included in this Plan.SECTION 9: OIL SPILL INFORMATION

A. Oil Spill Response Planning

All the proposed activities and facilities in this SEP will be covered by the Regional OSRP filed by Shell (Operator Number 0689) in accordance with 30 CFR 250. Updates to the Regional OSRP were filed with the BSEE October 26, 2010, March 15, 2011, May 31, 2011

, July 6, 2011 and August 1, 2011 and are pending approval. An updated OSRP Certification in accordance with 30 CFR 254.2 was accepted by the BSEE on August 4, 2011. Spill Response sites are as follows:

Primary Response Equipment Locations Preplanned Staging Location(s)
Fourchon, LA; Cameron, LA; Houma, LA; Lake

Charles , LA Lake Charles, LA ; Cameron, LA ; Fourchon ; LA

Table 9.1

–

Response Equipment and Staging Areas

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

Category Region al OSRP EP

Type of Activity 1 Drilling Rig Drilling Rig
Facility Location (area/block) MC 807 MC 393
Facility Designation 2 Subsea well A ◊ Subsea well Q
Distance to Nearest Shoreline (miles) 5 3 75

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

364 ,000* * BOPD

364 ,000 Bbls
Type of Oil(s)

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

API Gravity(s) 4 2 6 o 37.5 o

Table 9.2 - Worst Case Scenario Determination

*24 hour rate (365,000 BOPD 30 day average) **24 hour rate ( 353 ,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 (pending BOEM approval).

Since Shell has the capability to respond to the appropriate worst-case spill scenario included in its regional OSRP, updated with the BOEM October 26, 2010, March 15, 2011, May 31, 2011

, July 6, 2011 and August 1, 2011 and is pending approval, and 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 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 SEP.B. Oil Spill Response Discussion

1. Volume of the Worst Case Discharge
Please refer to Section 2j and 9(iv) of this SEP.

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 impact. Offshore areas along the trajectory between the source and land segment contact could be impacted. The land segmen t contact probabilities are shown in Table 9.C.1.

Area/Block OCS

- G Launch

Area Land Segment Contact %

Exploratory

MC 393 26254 57 Cameron, LA 1 Vermilion, LA 1 Iberia, LA

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

- Plaquemi nes, 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

Table 9.C.1 Probability of Land Segment Impact C. Resource Identificati on

The locations identified in Table 9.C.1 are the highest probable land segments to be impacted using the BOEM OSRAM. The environmental sensitivities are identified using the appropriate National Oceanic and Atmospheric Administration (NOAA) Environmental Sensitivity 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), sensitive 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 of 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 environmental importance that potentially could be impacted by the Mississippi Canyon 393 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. 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. Plaquemines Parish includes two National Wildlife Refuges: Breton National Wildlife Refuge and Delta National Wildlife Refuge. 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

co ordinated response 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 identified 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 393 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 and dispersion rates. Below is a table outlining the applicable evaporation and dispersion quantities:

Mississippi Canyon 393 Calculations

(BBLS)

i. 30 Day Average WCD = 353,000 bbls

ii. Subsurface dispersion

– 25% (Water Depth = ~7,3 75’ )

- 88,200 bbls

iii. REMAINING WCD AFTER SUBSURFACE DISPERSION 264,800 bbls

iv. Surface dispersion and evaporation

– 25%

- 66,200 bbls

TOTA L REMAINING ~198,600 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 skimmers 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 viable 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 EquipmentUpon 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, shoreline 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 deployment). The Incident Commander 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 to the maximum extent practicable, within 43.5 hours based on the equipment’s effective de-rated recovery 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 COTP and the RRT.

Subsea Control and Containment: Shell, as a founding member of the Marine Well Containment Company (MWCC), will have access to the Incidence Response Command System (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 393 will be addressed in Shell’s NTL 2010-N 10

submission at the time the APD is submitted.

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

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 capability of approximately 585,800 barrels/day. Temporary storage associated with the identified skimming and temporary storage equipment equals approximately 498,1 24 barrels.

D e

- rated Recovery Rate (bopd) Storage (bbls) Offshore Recovery and Storage 478,907 480,900 Nearshore Recovery and Storage 106,993 17,224

Total 585,840 498,124

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 spills. 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 disperse approximately7,704 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 per day. For continuing dispersant op erations, 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 List

Vessel 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 purpose-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 Control 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 optimal 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 -Situ 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 withtwo vessels capable of towing fire boom, guide boom or tow line with either a handheld or aeriallydeployed 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 systems 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, recent 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 in OSRP. In-situ burning along certain 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 addition, Shell will assess the situation

an d 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 limitations 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, shoreline 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 surveillance 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 ensurethat 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 operations. 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 effective 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 protect 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 dispersant 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.

B. 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 MapTable 9.D.4 Offshore On-Water Recovery and Storage Activation ListTable 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.4 Offshore On-Water Recovery and Storage Activation List (continued)Table 9.D.5 Nearshore On-Water Recovery and Storage Activation L istTable 9.D.5 Nearshore On-Water Recovery and Storage Activation List (continued)Table 9.D.5 Nearshore On-Water Recovery and Storage Activation List (continued)Table 9.D.5 Nearshore On-Water Recovery and Storage Activation List (continued)Table 9.D.6 Aerial Surveillance Activation ListTable 9.D.7 Offshore Aerial Dispersant Activation ListTable 9.D.8 Offshore Boat Spray Dispersant Activation List

Table 9.D.9 Control, Containment, and Subsea Dispersant Package Activation ListTable 9.D.10 In-Situ Burn Equipment Activation ListTable 9.D.10 In-Situ Burn Equipment Activation List (continued)Table 9.D.10 In-Situ Burn Equipment Activation List (continued)Table 9.D.10 In-Situ Burn Equipment Activation List (continued)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 monitor the current beneath the Rig. 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 BOEM:

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 SEP will not be conducted within the Protective Zones of the Flower Garden

Banks and Stetson Bank.SECTION 11 : LEASE STIPULATIONS INFORMATION

Lease OCS- G 26254 was part of Lease Sale #190, held on March 17, 2004. The lease is in its primary term. The lease is not part of a Biological Sensitive Area, known Chemosynthetic Area, or Shipping Fairway. See Section 6 of this plan for site specific archeological information.

Stipulation No. 3

–

Military Areas This lease is in the Water Test Area of the Eglin Water Test Areas 1 and 3. 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 Department 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. 6

–

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, Environmental Mitigation Measures Information, Incidental takes Section 18, Environmental Impact AssessmentSECTION 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 & 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 OSRP. 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 2007-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 Operations Information, transportation systems, & produced liquid hydrocarbon transportation vessels are not included in this SEP 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 Tug boats 200,000 2 Three days Anchor handling vess el 100,000 3 20 days Helicopter 76 0 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 393

C. Drilling Fluids Transportation

The following table is required for operations in the State of Florida and is being provided as information only:

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

OSV Synthetic

- base drilling fluids 11,000 bbls max per voyage Tanks below deck onboard OSV

D. Solid and Liquid Wastes Transportation

See Section 7, Table 7B.

E. Vicinity Map

See Section 18, Figure 18.1 for Vicinity Map.SECTION 15 : ONSHORE SUPPORT FACILITIES INFORMATION

A. General

Name Location Existing/New/Modified

Fourchon Port Fourchon, LA Existing

Boothville Heliport Boothville, LA Existing

The onshore support bases for water and air transportation will be the existing terminals in Boothville and Fourchon, Louisiana. The Fourchon boat facility is operated by Shell 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 Boothville, LA is located at 38963 Hwy. 23, Boothville, LA 70041.

B. Support Base Construction or Expansion

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

C. Support Base Construction or Expansion Timetable

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

D. Waste Disposal

See Section 7, Tables 7A and 7B.

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

Louisiana Coastal Zone Consistency was granted in Plan N-8379 on June 2, 2005, and is not required for Supplmental Exploration Plans.

Alamaba Coastal Zone Consistency is required for a Supplemental Exploration Plan and the consistency

follows.ALABAMA

COASTAL ZONE MANAGEMENT

CONSISTENCY CERTIFICATION

SUPPLEMENTAL EXPLORATION PLAN

Type of Plan

MISSISSIPPI CANYON Block 393

Area and Blocks

OCS-G 26254

Lease Number

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

Enforceable Policies.

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

SHELL OFFSHORE INC.

Operator

____________________________________________

Sylvia Bellone Certifying Official

1 1 / 0 2 /2011

DateCoastal Zone Management Consistency Information

For the State of Alabama

In accordance with 30 CFR 250.226(a) and (b)

, Shell 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 information 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 SEP.

B. OTHER INFORMATION

(1) Shell shall utilize a shore base in Fourchon, Louisiana for water support and PHI’s Boothville terminal for air traffic for the proposed activities.

(2) As per NTL 2008-G04 , the following items have been identified as being required:

 A discussion 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 S EP

.

 All operations are covered by Shell’s regional OSRP, which has been updated 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

pr oposed 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 and 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 conflicts 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 association 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 techniques 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 practicable 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 BOEM has regulations in place which explicitly prohibit the disposal of equipment, 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 marine 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 recreational resources.

Transportation

- Alabama’s transportation resources are not expected to be impacted, as shore bases in Fourchon and Boothville, Louisiana will be utilized for the proposed operations. Also, boats will not travel through any sensitive coastal areas off of the coast of

Alabama.

NATURAL RESOURCE PROTECTION POLICIES

Biological Productivity - All uses and activities shall be planned, sited, designed, construc ted 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 water 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 coastal 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 BOEM regulations, the US EPA’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 not expected to have significant impacts on onshore air quality because of the prevailingatmospheric 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 and navigation canals are considered the most significant impacting factors to wetlands and neither is proposed in the SEP. 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 contacting 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 operated 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 impacts 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 helicopter 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 expected

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 platforms, 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 turtle 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 discharges 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 maintained to avoid to the maximum extent practicable adversealteration of cultural resources. No impacts are expected to adversely affect historical, architectural, or archaeological sites. Should any historical, architectural, or archaeological resource be discovered 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)

Introduction

Project Summary

Shell is submitting a SEP for MC Block 393. Shell submitted an initial EP for Well A in MC 393, which was approved by the former Minerals Management Service (MMS) on 7 July 2005 (Plan Control No. N-8379). Shell is now submitting a SEP that includes six exploration wells in MC 393; these are A, Q, QST (a sidetrack to be drilled from the Q surface hole location), R, S, and T. This SEP also incorporates the revised blowout scenario and worst case discharge (WCD) information as required by Notice to Lessees and Operators (NTL) 2010-N06.

The lease area is 75 miles (120 km) from the nearest shoreline (Louisiana), 162 miles (261 km) from the onshore support base at Port Fourchon, Louisiana, and 100 miles (161 km) from the helicopter base at Boothville, Louisiana ( Figure 18. 1 ). All miles in this EIA are statute miles. Water depths at the wellsites range from 7,301 to 7,385 ft (2,225 to 2,251 m).

The Transocean Deepwater Nautilus , a moored semisubmersible rig, or an equivalent rig will be used for drilling. Drilling of wells will commence during the second quarter of 2012 and should be finished by the second quarter of 2016. The average time to drill a well will be approximately 100 days for wells A, R, S, T, and 107 and 62 days for Q and QST, respectively.

Purpose of the EIA

This Environmental Impact Analysis (EIA) was prepared pursuant to the requirements of the Outer Continental Shelf Lands Act (OCSLA), 43 United States Code (U.S.C.) §§ 1331-1356, and other regulations, including 30 Code of Federal Regulations (CFR) 250.212(o) and 250.227. The EIA is a project- and site- specific analysis of Shell’s planned activities under this EP. In keeping with the reorganization of the Bureau of Ocean Energy Management, Regulation, and Enforcement (BOEMRE) on October 1, 2011, into two separate agencies, Shell understands that the new Bureau of Ocean Energy Management (BOEM) will review this EIA and prepare a site-specific environmental assessment (SEA) for the project. This EIA complies with guidance provided in existing NTLs issued by the former MMS and BOEMRE, including NTL 2008-G04. Throughout this EIA, when existing guidance and general agency activities are referred to, “BOEM” is meant to subsume the former agencies and to represent the continuous regulatory entity now called BOEM. The former agency names (MMS and BOEMRE) are used only when referring to particular historical documents published under those names. In addition, until regulations promulgated under 30 Code of Federal Regulations (CFR) & NTLs are reissued under one of the two new agencies, the EIA will refer to the former BOEMRE as BOEM when addressing

30 CFR or the NTLs.

The EIA presents data, analysis, and conclusions to support BOEM reviews as required by the National Environmental Policy Act (NEPA) and other relevant Federal laws, including the Endangered Species Act (ESA) and Marine Mammal Protection Act (MMPA), as the BOEM considers this SEP for approval. It also identifies the mitigation measures Shell will implement in connection with the planned activities.Figure 18. 1. Vicinity map for the lease area.As specified in NTL 2008-G04, an EIA is a project-specific analysis that focuses on the impacts of a specific plan. This EIA addresses the impact-producing factors (IPFs), resources, and impacts associated with the activities proposed in this SEP including drilling of wells. The EIA also incorporates the revised blowout scenario and WCD information required by NTL 2010-N06.

The BOEM has performed numerous environmental evaluations of oil and gas activities on the Gulf of Mexico Outer Continental Shelf (OCS). Potential impacts were analyzed at a broader level in the Programmatic Environmental Impact Statement (EIS) for the OCS Oil and Gas Leasing Program (MMS, 2007a) and in multi-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008b), as well as the Environmental Assessment (EA) for Gulf of Mexico deepwater operations and activities (MMS, 2000 ) and a Grid EA for the Thunder Horse Project in MC 777 [Grid 16] (MMS, 2002).

These studies generated critical data and advanced the large body of existing knowledge on the Gulf of Mexico OCS. They analyze potential impacts on the natural environment, the socioeconomic effects of exploration and development activities, and other regional resources. Numerous technical studies address the likely trajectory of spilled oil, the effects of underwater noise on threatened and endangered species, and other IPFs. The studies inform agency decision-making on lease offerings, mitigation measures and lease stipulations, operational requirements, and permit restrictions. This substantial body of work, which in part forms the basis for the evaluation presented here, will allow the BOEM and other regulatory agencies to evaluate Shell’s SEP and ensure that oil and gas exploration and development activities are performed in an environmentally sound manner, with minimal impacts on the environment. Shell has incorporated these comprehensive environmental analyses by reference and built on them with project- and site-specific analyses.

OCS Regulatory Framework

The regulatory framework for OCS activities in the Gulf of Mexico has been summarized by

MMS (2010). Under the OCSLA, the U.S. Department of the Interior (USDOI) is responsible for the administration of mineral exploration and development of the OCS. Within the USDOI, the BOEM is charged with the responsibility of managing and regulating the development of OCS oil and gas resources in accordance with the provisions of the OCSLA. The BOEM operating regulations are in 30 CFR Parts 250, 251, and 254.

In implementing its responsibilities under the OCSLA and NEPA, the BOEM must consult numerous Federal departments and agencies that have authority to govern and maintain ocean resources pursuant to other Federal laws. Among these are the U.S. Coast Guard (USCG), U.S. Environmental Protection Agency (USEPA), U.S. Fish and Wildlife Service (USFWS), and the National Oceanic and Atmospheric Administration (NOAA) through the National Marine Fisheries Service (NMFS). Federal regulations establish consultation and coordination processes with Federal, State, and local agencies (e.g., the ESA, MMPA, Coastal Zone Management Act of 1972, and the Magnuson-Stevens Fishery Conservation and Management Act).

NTLs are formal documents issued by the BSEE that provide clarification, description, or interpretation of a regulation or standard; provide guidelines on implementing a special lease stipulation or regional requirement; provide a better understanding of the scope and meaning of a regulation by explaining the BOEM interpretation of a requirement; or transmit administrative information such as current telephone listings or changes in BOEM personnel or office address.

Table 18. 1 lists and summarizes the NTLs that are referenced in this EIA.Table 18. 1. Notices to Lessees and Operators (NTLs) that are referenced in this Environmental Impact Analysis (EIA).

NTL Title Summary

2010

- N10 Statement of Compliance with

Applicable Regulations and

Evaluation of Information Demonstrating Adequate Spill Response and Well

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

blowout or other loss of well control.

2010

- N06 Information Requirements for

Exploration Plans, Development and Production Plans, and Development Operations Coordination

Documents on the OCS Rescinds the limitations set forth in NTL 2008

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

2009

- G40 Deepwater Benthic

Communities Guidance for avoiding and protecting high

- density deepwater benthic commu nities (including chemosynthetic and deepwater coral communities) from damage caused by OCS oil and gas activities in water depths greater than 984 ft (300 m). Prescribes separation distances of 2,000 ft (610 m) from each mud and cuttings discharge locati on and 250 ft (76 m) from

all other seafloor disturbances.

2009

- G39 Biologically

- Sensitive

Underwater Features and

Areas Guidance for avoiding and protecting biologically

sensitive features and areas (i.e., topographic features, pinnacles, low

- relief live bottom areas, and other potentially sensitive biological features) when conducting OCS operations in water depths less than 984 ft (300 m) in the Gulf of Mexico.

2009

- G06 Military Warning and Water

Test Areas Provides contact links to individual command

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

2008

- G04 Information Requirements for

Exploration Plans and Development Operations

Coordination Documents Guidance o n the information requirements for OCS plans, including EIA requirements and information regarding compliance with the provisions of the Endangered Species Act and Marine Mammal Protection

Act.

2007

- G04 Vessel Strike Avoidance and

Injured/Dead Protected

S pecies Reporting Recommends protected species identification training,

recommends that vessel operators and crews maintain a vigilant watch for marine mammals and slow down orNTL Title Summary stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species.

2007

- G03 Marine Trash and Debris

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

2005

- G07 Archaeological Resource

Surveys and Reports Provides guidance on regulations regarding

ar chaeological discoveries, specifies requirements for archaeological resource surveys and reports, and outlines options for protecting archaeological resources.

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 SEP Section 9 ). The OSRP demonstrates Shell’s capabilities to rapidly and effectively manage oil spills that may result from drilling operations. Despite the extremely low likelihood of a large oil spill occurring during the project, Shell has designed its response program based upon a regional capability of responding to a range of spill volumes that increase from small operational spills up to and including a WCD from a well blowout. Shell’s program meets the response planning requirements of the relevant coastal states and Federal oil spill planning regulations. The OSRP includes information regarding Shell’s regional oil spill organization and dedicated response assets, potential spill risks, and local environmental sensitivities. The 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.

EIA Organization

The EIA is organized into Sections A through I corresponding to the information required by NTL 2008-G04, which provides guidance regarding information required by 30 CFR Part 250 for EPs. The main impact-related discussions are in Section A (Impact-Producing Factors) and

Section C (Impact Analysis).A. Impact-Producing Factors

Table 18. 2 is a matrix of IPFs and potentially affected environmental resources adapted from

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

-- ) indicates no impact or negligible impact. Where there may be an effect, an analysis is provided in Section C . Potential IPFs for the proposed activity are listed below and briefly discussed in the following subsections:

Drilling rig presence (including noise and lights); Physical disturbance to the seafloor; Air pollutant emissions; Effluent discharges; Water intake; Onshore waste disposal; Marine debris; Support vessel and helicopter traffic; and

Accidents.

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

The wells will be drilled using the Transocean Deepwater Nautilus or a similar moored semisubmersible rig. The rig will be on site for an estimated 100 days per well. Three offshore support vessels will be used during the drilling program and at least one of these will always be in the vicinity of the drilling rig to provide assistance as necessary. The physical presence of a drilling rig in the ocean can attract pelagic fishes and other marine life, as discussed in

Section C.5.1 . A semisubmersible rig maintains buoyancy using ballasted, watertight pontoons located below the sea surface. The operating deck is located above the tops of passing waves. Structural columns connect the pontoons and operating deck. When the rig moves its location, the pontoons are de-ballasted so that the rig can float on the sea surface. The Nautilus uses anchors to hold or adjust its position.

Drilling operations produce noise that includes strong tonal components at low frequencies, including infrasonic frequencies in at least some cases (MMS, 2000). Drilling noise from semisubmersibles is not particularly intense and is strongest at low frequencies, averaging 10 to

500 Hz (Richardson et al., 1995). From a semisubmersible, sound and vibration are transmitted to the water either through the air or the risers (MMS, 2000). Drilling rigs also maintain exterior lighting for navigational and aviation safety in accordance with Federal regulations.

A.2 Physical Disturbance to the Seafloor

The semisubmersible rig will be held in place by either suction pile anchors or variable load anchors that will be deployed with an anchor radius of 15,500 ft (4,727 m) and within a clearance distance of 16,500 ft (5,029 m) around each wellsite. According to the MMS (2007b) semisubmersible rigs disturb about 5-7 ac (2-3 ha), depending on their mooring configurations. In taking the more conservative approach of 7 ac (3 ha) the total seafloor disturbance area is estimated to be 35 ac (15 ha) for the six wellsites (five surface locations). During anchor deployment, cables will be resting on the seafloor only during the pre- and post-installation phase; once the rig arrives on location, cables are pulled taut towards the rig. The cables do not sweep the seafloor or cross any sensitive features, and therefore are expected to have little or no physical impact on the seafloor.Table 18.2. Matrix of impact-producing factors and affected environmental resources. X = potential impact; dash (

-- ) = no impact or negligible impact.

Environmental Resources Impact

- producing Factors Drilling Rig
Presence (incl. noise and lights) Physical

Disturbance to Seafloor Air

Pollutant
Emissions Effluent

Discharges Water

Intake Onshore

Waste Disposal Marine

Debri s Support

Vessel/Helo Traffic 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 Biot a 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 (endangere d)

-- -- -- -- -- -- -- 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) Pip ing Plover (threatened)

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

-- -- -- -- -- -- -- -- -- X (6) Gulf sturgeon (threatened)

-- -- -- -- -- -- -- -- -- X (6) Beach mice (endangered)

-- -- -- -- -- -- -- -- -- X (6) Coastal and Marine Bi rds 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)
Wetlan ds 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 s afety

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

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

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

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

-- -- -- -- -- -- -- -- -- X (6)Tabl e 18. 2 Footnotes and Applicability:

(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 block.

(2) Activities with any bottom disturbance within an OCS lease block protected through the Live Bottom (Pinnacle Trend) Stipulation attached to an OCS lease.
The Live Bottom (Pinnacle Trend) Stipulation is not applicable to the lease area.

(3) Activities within any Eastern Gulf OCS block where seafloor habitats are protected by the Live Bottom (Low-Relief) Stipulation attached to an OCS lease.
The Live Bottom (Low-Relief) Stipulation is not applicable to the lease area.

(4) Activities on blocks designated by the BOEM as being in water depths 300 m or greater.
No impacts on high-density deepwater benthic communities are anticipated. There are no features indicative of high-density chemosynthetic communities or coral communities within 2,000 ft (610 m) of any drilling mud/cuttings discharge location. Features or areas that could support high-density chemosynthetic

communities are not located withi n 250 ft (76 m) of any seafloor disturbances resulting from the use of

anchors

(5) Exploration or production activities where H 2 S concentrations greater than 500 ppm might be encountered. Based on CFR 250.490(c), Shell requests that the BOEM classify the area in the proposed drilling operations as
an area where the presence of H 2 S has been confirmed.

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

Section C

. (7) All activities that involve seafloor disturbances, including anchor emplacements, in any OCS block designated
by the BOEM as having high-probability for the occurrence of shipwrecks or prehistoric sites, including such
blocks that will be affected that are adjacent to the lease block in which your planned activity will occur. If the
proposed activities are located a sufficient distance from a shipwreck or prehistoric site that no impact would
occur, the EIA can note that in a sentence or two.
No impacts on archaeological resources are expected. The lease area is on the list of archaeology survey blocks but not on the list of high-probability blocks for shipwrecks (MMS, 2008a). The seafloor patterning
and acoustic characteristics of the sonar targets detected during the archaeological survey conclude that
they are either geologic in origin or are modern debris. However, there was one partially buried sonar
contact along a proposed anchor location that will be avoided during anchor placement. The lease is well
beyond the 60-m depth contour used by the BOEM as the seaward extent for prehistoric archaeological
site potential in the Gulf of Mexico.

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

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

. (9) Production activities that involve transportation of produced fluids to shore using shuttle tankers or barges.
Not applicable.

## A.3 Air Pollutant Emissions

Estimates of air pollutant emissions are provided in SEP Section 8 . Offshore air pollutant emissions will result from operations of the drilling rig, as well as service vessels and helicopters. These emissions occur mainly from combustion of diesel fuel. The combustion of fuels occurs on diesel-powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended particulate matter (PM), sulfur oxides (SO

x ), nitrogen oxides (NO

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

The Air Quality Emissions Report prepared in accordance with the BOEM requirements shows that the projected emissions are below exemption levels; therefore, according to 30 CFR 250.303, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required. However, Shell will use

low -sulfur fuel to further reduce any possible impacts.

A.4 Effluent Discharges

Effluent discharges are summarized in SEP Section 7 . Offshore discharges will be in accordance with the National Pollutant Discharge Elimination System (NPDES) General Permit No. GMG290000 issued by the USEPA. Discharges will be in compliance with and monitored as required by the permit.

Water-based drilling mud and cuttings will be released at the seafloor during the initial well intervals before the marine riser is set that allows returns to the surface. Excess cement slurry also will be released at the seafloor during casing installation for the riserless portion of the drilling operations.

A synthetic-based mud (SBM) system will be used after the riser is installed. Unused or residual SBM will be collected and transported to Port Fourchon, Louisiana, for disposal in an approved facility. SBM cuttings will be discharged overboard via a downpipe below the water surface, after treatment that complies with the 6.9% NPDES permit requirement for retention of SBM fluid on cuttings. The estimated volume of SBM cuttings to be discharged is provided in SEP Section 7

.

Other effluent discharges in accordance with the NPDES permit will include excess cement, non-contact cooling water, treated sanitary and domestic wastes, deck drainage, desalination unit brine, uncontaminated fire water, and ballast water.

A.5 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 ( SEP Table 7a ).

Section 316(b) of the Clean Water Act requires NPDES permits to ensure that the location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impacts from impingement and entrainment of aquatic organisms. Construction of the rig planned for use in this SEP, the Transocean Deepwater Nautilus

, started prior to 17 July 2006, and therefore is not subject to the cooling water intake permit requirements of NPDES Permit GMG290000. If a different rig is selected, it will comply with applicable NPDES requirements.A.6 Onshore Waste Disposal

Wastes generated during drilling are tabulated in SEP Section 7 . Non-hazardous 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. Additionally, non-hazardous recyclable waste will be recycled at Omega Waste Management, Patterson, Louisiana, or at ARC of New Iberia, Louisiana. Hazardous waste such as paints, solvents, and unused chemicals will be disposed of at Safety Kleen Systems, Inc., Denton, Texas, while used oil and glycol will be sent to Omega Waste Management or ARC for recycling. Universal waste including batteries, lamps, glass, and mercury-contaminated waste will be recycled at Lamp Environmental Industries, Hammond, Louisiana. At the onshore facilities, wastes will be recycled or disposed of according to applicable regulations.

A.7 Marine Debris

Trash and debris released into the marine environment can harm marine mammals, turtles, and birds through entanglement and ingestion. Shell will adhere to the International Convention for the Prevention of Pollution from Ships (MARPOL 73/78) Annex V requirements, USEPA and USCG regulations, and BOEM regulations and NTLs regarding solid wastes. BOEM regulations at

30 CFR 250.300(a) and (b)(6) prohibit operators from deliberately discharging containers and other similar materials (e.g., trash and debris) into the marine environment, and

30 CFR 250.300(c) requires durable identification markings on equipment, tools and containers (especially drums), and other material. USCG and USEPA regulations require operators to become proactive in avoiding accidental loss of solid waste items by developing waste management plans, posting informational placards, manifesting trash sent to shore, and using special precautions such as covering outside trash bins to prevent accidental loss of solid waste. Shell complies with NTL 2007-G03, which instructs operators to exercise caution in the handling and disposal of small items and packaging materials, requires the posting of placards at prominent locations on offshore vessels and structures, and mandates a yearly marine trash and debris awareness training and certification process. Shell’s compliance with applicable laws, regulations, and NTL 2007-G03 will avoid significant impacts on the environment.

A.8 Support Vessel and Helicopter Traffic

Shell will use existing shorebased facilities at Port Fourchon and Boothville, Louisiana, for onshore support for water and air transportation, respectively. No terminal expansion or construction is planned at either location.

The supply base at Port Fourchon is operated by Shell and located on Bayou LaFourche, approximately 3 miles (5 km) from the Gulf of Mexico. During drilling, the project will be supported by two crew boats and three offshore support vessels; crew boats and support vessels will make two round-trips per week between the drilling facility and the onshore supply base, and there will likely be at least one vessel in the field at all times. The boats will normally move tothe project area via the most direct route from the shorebase. Two tugboats and three anchorhandling vessels will assist in mobilization and demobilization of the rig.

The air transportation base will be the PHI Heliport in Boothville, Louisiana. A helicopter will make one round-trip daily between the drilling rig and the heliport. The helicopter will be used to transport personnel and small supplies and will normally take the most direct route of travel between the helicopter base and the lease area when air traffic and weather conditions permit. Helicopters typically maintain a minimum altitude of 700 ft (213 m) while in transit offshore, 1,000 ft (305 m) over unpopulated areas or across coastlines, and 2,000 ft (610 m) over populated areas and sensitive habitats such as wildlife refuges and park properties.A.9 Accidents

A.9.1 Types of Accidents Evaluated

The analysis in this EIA focuses on two potential accidents:

a small fuel spill, which is the most likely type of spill during OCS development activities; and an oil spill resulting from an uncontrolled blowout. A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s we ll control and blowout prevention measures as detailed in SEP Section 2j

.

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

.

The lease sale EIS (MMS, 2007b) analyzes three other types of accidents: chemical spills, vessel collisions, and loss of well control. These accidents are discussed briefly in Section A.9.4

.

A.9.2 Small Fuel Spill

Spill Size . According to the analysis in MMS (2007b), the most likely type of small spill (<1,000 bbl) as a result of OCS activities is a minor diesel fuel spill. Historically, most diesel spills

have been < 1 bbl, and this size is predicted to be the most common in ongoing and future OCS activities in the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b). The average size for spills < 1 bbl is 0.07 bbl, and the median size for spills of 1 to 10 bbl is 3 bbl (MMS, 2007b). For this analysis, a small diesel fuel spill of 3 bbl is assumed. Operational experience suggests that the most likely cause of such a spill would be a hose rupture resulting in the loss of the contents of a fuel transfer hose, which is less than 3 bbl.

Spill Fate . The fate of a small fuel spill in the lease area would depend on meteorological and oceanographic conditions at the time, as well as the effectiveness of spill response activities. However, given the open ocean location of the lease area, the duration of a small spill and the opportunity for impacts to occur would be very brief.

The water-soluble fractions of diesel are dominated by two- and three-ringed polycyclic aromatic hydrocarbons (PAHs), which are moderately volatile (National Research Council [NRC], 2003). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation . Diesel’s density is such that it will not sink and pool on

the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high-suspended solids loads (NRC, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

The fate of a small diesel fuel spill was estimated using NOAA’s ADIOS2 (Automated Data Inquiry for Oil Spills) model. This model uses the physical properties of oils in its database to predict the rate of evaporation and dispersion over time, as well as changes in the density, viscosity, and water content of the product spilled. It is estimated that over 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha) depending on sea state and weather conditions.

The ADIOS2 results, coupled with spill trajectory information discussed below for a large spill, indicate that a small fuel spill would not have any impacts on coastal or shoreline resources. The lease area is 75 miles (120 km) from the nearest shoreline (Louisiana). Modeling results discussed below indicate that a spill in the lease area would have a 21% probability of contacting the nearest Louisiana shoreline (Plaquemines Parish) within 30 days after a spill. By that time, essentially 100% of a small fuel spill would have been dispersed or evaporated by natural processes, even if no response measures were implemented. MMS (2007b) similarly concludedthat spills <1,000 bbl are not expected to persist as a slick on the surface of the water beyond a few days and are unlikely to make landfall or reach coastal waters prior to breaking up.

MMS (2007b) noted that this conclusion is supported by a previous analysis of 3-day trajectory model runs, previous weathering analyses, and historical records of spill incidents.

Spill Response . In the unlikely event of a fuel spill, response equipment and trained personnel would be available to ensure that any spill effects are localized and would result only in short-term environmental consequences. SEP Section 9b provides a detailed discussion of Shell’s response to a spill.

A.9.3 Large Crude Oil Spill

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures detailed in

SEP Section 2j . Blowouts are rare events and most do not result in oil spills. Holand (1997) estimated a probability of 0.0021 for a deep drilling blowout during exploration drilling based on U.S. Gulf of Mexico data. An updated analysis using the SINTEF database estimates a blowout frequency of 0.0017 per exploratory well for non-North Sea locations (International Association of Oil & Gas Producers, 2010). As noted by MMS (2007b), from 1992 to 2005, half of blowouts lasted less than half a day, and fewer than 10% of blowouts resulted in spilled oil.

The risk of a blowout during this project is significantly lower than indicated by these statistics because the well design and drilling program were developed using information gathered during the drilling of the previous wells in MC 348 and 392, and DeSoto Canyon 353. During drilling of the previous wells, the reservoirs were logged and evaluated. Substantial data associated with the reservoirs were gathered including core, pressure, and fluid data. Data gained during these earlier operations provide substantial information that was used in preparing for the proposed operation.

Spill Size . Shell has calculated a WCD for this SEP, using the requirements prescribed by NTL 2010-N06. The WCD is 364,000 bbl for the first day with a 30-day average of 353,000 barrels per day (BPD). The estimated time to drill a relief well is 128 days, and the total volume of a spill over this duration is estimated to be 44.9 million barrels of oil (MMBO). The detailed analysis of this calculation can be found in SEP Section 2j . The WCD scenario for this SEP, in terms of both initial and the sustained rates, has a low probability of being realized. Some of the factors that are likely to reduce rates and volumes, and are not included in the WCD calculation, include but are not limited to obstructions or equipment in the wellbore, well bridging, and early intervention such as containment capabilities.

Shell has a robust system in place to prevent blowouts. Included in SEP Sections 2j and 9b is Shell’s response to NTL 2010-N06, which includes descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout. Shell will also comply with NTL 2010-N10 and the Interim Final Drilling Safety Rule, which specify additional safety measures for OCS activities.

Spill Trajectory . The fate of a large oil spill in the lease area would depend on meteorological and oceanographic conditions at the time. The Oil Spill Risk Analysis (OSRA) model is a computer simulation of oil spill transport that uses realistic data for winds and currents to predict the fate of a spill of at least 1,000 bbl. The OSRA report by Ji et al. (2004) provides conditional contact probabilities for shoreline segments. The results for Launch Area 57 (where the lease area is located) are presented in Table 18. 3 . The model predicts shoreline contact with 4 parishes in Louisiana within 3 or 10 days. After 30 days, 14 counties and parishes from Cameron, Louisiana to Bay, Florida may be contacted. Plaquemines Parish, Louisiana has the greatest probability of shoreline contact, with a 21% chance within 30 days.Table 18. 3. Conditional probabilities of a spill in the lease area contacting shoreline segments (From: Ji et al., 2004). Values are conditional probabilities that a hypothetical spill in the lease area (represented by OSRA Launch Area 57) could contact shoreline segments within 3, 10, or 30 days.

Shoreline Segment County or Parish and State Conditional Probability of Contact a (%) 3 Days 10 Days 30 Days

C13 Cameron, LA

-- -- 1

C14 Vermilion, LA

-- -- 1

C17 Terrebonne, LA

-- 1 2

C18 Lafourche, LA

-- 1 2

C20 Plaquemines, LA 4 14 21

C21 St. Bernard, LA

-- 1 3

C22 Hancock and Harrison,

MS -- -- 1

C23 Jackson, MS

-- -- 1

C24 Mobile, AL

-- -- 1

C25 Baldwin, AL

-- -- 1

C26 Escambia, AL

-- -- 1

C28 Okaloosa, FL

-- -- 1

C29 Walton, FL

-- -- 1

C30 Bay, FL

-- -- 1

a Conditional probability refers to the probability of contact within the stated time period, assuming that a spill has occurred (

-- indicates less than 0.5%).

The OSRA model does not evaluate the fate of a spill over time periods longer than 30 days, nor does it predict the fate of a release that continues over a period of weeks or months. Also as noted by Ji et al. (2004), the OSRA model does not take into account the chemical composition or biological weathering of oil spills, the spreading and splitting of oil spills, or spill response activities. The model does not assume a particular spill size but has generally been used by the BOEM to evaluate contact probabilities for spills greater than 1,000 bbl.

Weathering . Following an oil spill, several physical, chemical, and biological processes, collectively called weathering, interact to change the physical and chemical properties of the oil, and thereby influence its harmful effects on marine organisms and ecosystems. The most important weathering processes include spreading, evaporation, dissolution, dispersion into the water column, formation of water- in -oil emulsions, photochemical oxidation, microbial degradation, adsorption to suspended PM, and stranding on shore or sedimentation to the seafloor (NRC, 2003).

Weathering decreases the concentration of oil and produces changes in its chemical composition, physical properties, and toxicity. The more toxic, light aromatic and aliphatic hydrocarbons are lost rapidly by evaporation and dissolution from the slick on the water surface. Evaporated hydrocarbons are degraded rapidly by sunlight. Biodegradation of oil on the water surface and in the water column by marine bacteria removes first the n-alkanes and then the light aromatics from the oil. Other petroleum components are biodegraded more slowly. Photooxidation attacks mainly the medium and high molecular weight PAHs in the oil on the water surface.

Spill Response . Shell is a founding member of the Marine Well Containment Company (MWCC) and has access to an integrated subsea well control and containment system that can be rapidly deployed through the MWCC. The MWCC is a non-profit organization that assists with the subsea containment system during a response. The near-term containment response capability will be specifically addressed in Shell’s NTL 2010-N10 submission at the time an Application for Permit to Drill (APD) is submitted and will include equipment and services available to Shell throughMWCC’s d evelopment of near-term capability and other industry sources. Shell is a member of Clean Caribbean & Americas (CCA), Marine Spill Response Corporation (MSRC), Clean Gulf Associates (CGA), and Oil Spill Response Limited (OSRL), organizations that are committed to providing the resources necessary to respond to a spill as outlined in Shell’s Regional OSRP.

The experience of gaining control over the Macondo well has resulted in a better understanding of the necessary equipment and systems for well containmen t. 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 1 October 2010 [Bromwich, 2010]). Shell is further analyzing these advances and incorporating them into a comprehensive approach to help prevent and, if needed, control another deepwater well control incident. Shell is also investing in research and development to improve containment systems.

The primary offshore response would involve mechanical recovery. The primary response equipment that would be mobilized to the spill location for spills in normal and adverse weather conditions is included in the Offshore On-Water Recovery Activation List in the OSRP.

Chemical dispersant stockpiles are readily available from Gulf Coast State suppliers such as MSRC in Texas, Louisiana, Mississippi, and Florida; MWCC; CGA/Airborne Support, Inc. in Louisiana and Texas; and Clean Caribbean and Americas in Florida. Additional supplies are available from international vendors. Available equipment for surface and subsea application of dispersants, response times, and support resources are identified in the OSRP.

Open-water in

situ burning may also be used as a response strategy, depending on the circumstances of the release. If appropriate conditions exist and approval from the Unified Command is received, one or multiple in situ burning task forces could be deployed offshore.

See SEP Sections 2j and 9b for a detailed description of Shell’s site -specific response to a large oil spill for this plan. These sections, along with Shell’s OSRP, also include a description of surface and subsea containment capabilities that could be implemented in the event of a large oil spill at this site.

A.9.4 Other Accidents Not Analyzed in Detail

The lease sale EIS (MMS, 2007b) discusses three other types of accidents: chemical spills, vessel collisions, and loss of well control. These accidents are discussed briefly below. Other than the presence of hydrogen sulfide (H 2 S), which is addressed below, no other site-specific issues have been identified for this SEP. The analysis in the lease sale EIS for these topics is incorporated by

reference.

Chemical Spill . Chemicals are used in drilling operations to achieve technical goals in the drilling process, improve the efficiency and safety of drilling, and protect associated equipment. Chemicals used during exploration and drilling include surfactants, bentonite clays, olefins, inorganic salts, glycols, polymers, barite, and calcium carbonate. Supplies are renewed on a regular basis by transfer in containers from supply boats (Boehm et al., 2001). In addition to chemicals used in drilling fluids, the following chemicals are likely to be used on the rig: ethylene glycol (blowout prevention control fluid, used in closed cooling loops for crane and main engines and brake coolers), cement (used to cement casing in place), solvents (used in painting operations), hydraulic fluids (used in cranes and other hydraulic rig equipment), lubricating oil and grease (used in reciprocating and electrical equipment), and sodium hypochlorite (dilute, used as laundry bleach and disinfectant).

A study of environmental risks of chemical products used in OCS activities determined that only two chemicals could potentially affect the marine environment: zinc bromide and ammonium chloride (Boehm et al., 2001). The project addressed by this SEP does not anticipate the use ofzinc bromide or ammonium chloride. Most other chemicals are either nontoxic or used in small quantities. No significant impacts are expected from chemical spills.

Vessel Collisions . As summarized in MMS (2007b), vessel collisions occasionally occur during routine operations. Most collision mishaps are the result of service vessels colliding with platforms or vessel collisions with pipeline risers. Some of these collisions have caused spills of diesel fuel or chemicals. Shell will comply with USCG and BOEM-mandated safety requirements to minimize the potential for vessel collision s.

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

Shell has a robust system in place to prevent loss of well control. Included in this SEP is Shell’s
response to NTL 2010-N06, which includes descriptions of measures to prevent a blowout, reduce the likelihood of a blowout, and conduct effective and early intervention in the event of a blowout. Shell will also comply with NTL 2010-N10 and the Interim Final Drilling Safety Rule, which specify additional safety measures for OCS activities. See SEP Sections 2j and 9b for

further information.

H 2 S Release . Based on CFR 250.490(c), Shell has requested that the proposed drilling area be classified as an area where the presence of H 2 S has been confirmed. An H 2 S contingency plan will be prepared and filed with the APD.

B. Affected Environment

The lease area is in the north-central Gulf of Mexico, 75 miles (120 km) from the nearest shoreline (Louisiana), 162 miles (261 km) from the onshore support base at Port Fourchon, Louisiana, and 100 miles (161 km) from the helicopter base at Boothville, Louisiana ( Figure 18. 1 ).

There is no evidence of seafloor or near-surface faulting, slumping, anomalous amplitudes or fluid expulsion features in the vicinity of the proposed well locations A, Q, QST, R, S, and T in

MC 393. Water depths at these well locations range from 7,301 to 7,385 ft (2,225 to 2,251 m) ( Section 1, Attachment 1A ). The side-scan sonar survey confirmed the absence of pipelines and flowlines in the vicinity of MC 393. The sonar targets identified were not within 2,000 ft (610 m) of the proposed wellsites except for one target that was located 1,456 ft (444 m) from proposed well location T ( AOA Geophysics, Inc., 2004; Fugro Geoservices, Inc., 2009a) and two targets that were located 674 ft (205 m) and 1,780 ft (543 m) from Location A (Fugro Geoservices, Inc., 2007).

A detailed description of the regional affected environment is provided in recent EISs (MMS, 2007b, 2008b), including meteorology, oceanography, geology, air and water quality, benthic communities, threatened and endangered species, biologically sensitive resources, archaeological resources, socioeconomic conditions, and other marine uses. These regional descriptions are based on extensive literature reviews and are incorporated by reference. General background information is presented below, and brief descriptions of each potentially affected resource are presented in Section C , including site-specific and/or new information if

available.The local environment in the lease area is not known to be unique with respect to physical/chemical, biological, or socioeconomic conditions. Baseline environmental conditions in the lease area are expected to be consistent with the regional description of continental slope locations evaluated in recent lease sale EISs (MMS, 2007b, 2008b).

The lease area is approximately 28 miles (46 km) southeast of the Macondo spill site. Based on an analysis of satellite imagery (ESRI, 2010), the surface slick extended over the lease area prior to capping of the well; therefore, existing water quality in the lease area could have been temporarily affected. Macondo spill impacts are addressed in Section C.9 (Cumulative Impacts) where available and applicable.

C. Impact Analysis

This section analyzes the potential direct and indirect impacts of routine activities and accidents. Cumulative impacts are discussed in Section C.9 . Impacts have been analyzed extensively in recent multi-lease-sale EISs for the Western and Central Gulf of Mexico Planning Areas (MMS, 2007b, 2008b). Site-specific issues are addressed in this section as appropriate.

C.1 Physical/Chemical Environment

C.1.1 Air Quality

There are no site-specific air quality data for the project area. Due to the distance from shorebased pollution sources, offshore air quality is expected to be good. The attainment status of Federal OCS waters is unclassified because there is no provision in the Clean Air Act for classification of areas outside State waters (MMS, 2007b).

As of 30 August 2011, all Louisiana, Mississippi, Alabama, and Florida coastal counties and parishes are in attainment of the NAAQS for all criteria pollutants (USEPA, 2011). One coastal metropolitan area in Texas (Houston-Galveston-Brazoria) is nonattainment for 8-h ozone.

Winds in the region are driven by the clockwise circulation around the Bermuda High (MMS, 2007b). The Gulf of Mexico is located to the southwest of this center of circulation, resulting in a prevailing southeasterly to southerly flow, which is conducive to transporting emissions toward shore. However, circulation is also affected by tropical cyclones (hurricanes) during summer and fall and by extratropical cyclones (cold fronts) during winter.

IPFs potentially affecting air quality are air pollutant emissions and two types of accidents: a small fuel spill and a large oil spill.

Impacts of Air Pollutant Emissions

Air pollutant emissions are the only routine IPF likely to affect air quality. Offshore air pollutant emissions will result from the operation of the drilling rig as well as helicopters and service vessels. These emissions occur mainly from combustion or burning of diesel fuel. The combustion of fuels occurs primarily on diesel-powered generators, pumps, or motors and from lighter fuel motors. Primary air pollutants typically associated with OCS activities are suspended PM, SO
x , NO
x , VOCs, and CO.

Due to the distance from shore, routine operations in the project area are not expected to have any impact on air quality conditions along the coast. As noted in the lease sale EIS (MMS, 2007b), emissions of air pollutants from routine activities in the Central Gulf of Mexico Planning Area are projected to have minimal impacts to onshore air quality because of the prevailing atmospheric conditions, emission heights, emission rates, and the distance of theseemissions from the coastline. The Air Quality Emissions Report (see SEP Section 8 ) prepared in accordance with BOEM requirements shows that the projected emissions for PM, SO

x , NO
x , VOCs, and CO are below exemption levels; therefore, according to 30 CFR 250.303, the emissions will not significantly affect the air quality of the onshore area for any of the criteria pollutants. No further analysis or control measures are required. However, Shell will use low-sulfur fuel to further reduce any possible impacts.

The Breton Wilderness Area, which is part of the Breton National Wildlife Refuge (NWR), is designated under the Clean Air Act as a Prevention of Significant Deterioration (PSD) Class I air quality area. The BOEM coordinates with the National Park Service (NPS) and the USFWS if emissions from proposed projects may affect the Breton Class I area. Additional review and mitigation measures may be required for sources within 186 miles (300 km) of the Breton Class I area that exceed emission limits agreed upon by the administering agencies (NPS, 2010). The lease area is approximately 94 miles (151 km) from the Breton Wilderness Area. Shell does not anticipate any impact on the Class I area, but will comply with any emissions requirements as directed by the BOEM.

Impacts of a Small Fuel Spill

Potential impacts of a small spill on air quality are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b, 2008b). The probability of a small spill would be minimized by Shell’s preventative measures during routine ope rations, including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the extent and duration of air quality impacts from a small spill would not be significant.

A small fuel spill would affect air quality near the spill site by introducing VOCs through evaporation. The ADIOS2 model (see Section A.9.2 ) indicates that more than 90% of a small diesel spill would be evaporated or dispersed within 24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha) depending on sea state and

weather conditions.

A small fuel spill would not affect coastal air quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill

Potential impacts of a large oil spill on air quality are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b, 2008b).

A large oil spill would affect air quality by introducing VOCs through evaporation from the slick. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Additional air quality impacts could occur if response measures included in situ burning of the floating oil. Burning would generate a plume of black smoke and result in emissions of NOx, SO

x , CO, and PM, as well as greenhouse gases.

Due to the lease area location (75 miles [120 km] from the nearest shoreline), most air quality impacts would occur in offshore waters. Depending on the spill trajectory and the effectivenes s of spill response measures, coastal air quality could also be affected. Based on the OSRA modeling predictions ( Table 18. 3 ), Plaquemines Parish, Louisiana is the coastal area most likely

to be affected.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed inSEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on air quality are expected.

C.1.2 Water Quality

There are no site-specific water quality data for the lease area. Due to the lease location in deep, offshore waters, water quality is expected to be good, with low levels of contaminants. As noted in the lease sale EIS (MMS, 2007b), deepwater areas in the northern Gulf of Mexico are relatively homogeneous with respect to temperature, salinity, and oxygen. Kennicutt (2000) noted that the deepwater region has little evidence of contaminants in the dissolved or particulate phases of the water column. However, there are localized occurrences of natural seepage of oil, gas, and brines in near- su rface sediments and up through the water column.

The lease area is approximately 28 miles (46 km) southeast of the Macondo spill site. Based on satellite imagery (ESRI, 2010), the surface slick extended over the lease area during the spill, and therefore existing water quality in the lease area could have been temporarily affected. The Operational Science Advisory Team (OSAT, 2010) reported that after August 2010, waters and sediments in the deepwater Gulf of Mexico beyond 1.8 miles (3 km) from the Macondo wellsite were below USEPA acute and chronic benchmarks for PAHs and were not hypoxic. These observations indicate that baseline environmental conditions in the lease area are unlikely to have been significantly altered by the spill.

IPFs potentially affecting water quality are effluent discharges and two types of accidents: a small fuel spill and a large oil spill.

Impacts of Effluent Discharges

Discharges of treated SBM cuttings will produce temporary, localized increases in suspended solids in the water column around the drilling rig. In general, turbid water can be expected to extend between a few hundred meters and several kilometers down current from the discharge point (NRC, 1983; Neff, 1987). NPDES permit limitations and requirements will be met. After discharge, SBM retained on cuttings would be expected to adhere tightly to the cuttings particles and, consequently, would not produce much turbidity as the cuttings sink through the water column (Neff et al., 2000). There will be no persistent impacts on water quality in the lease area.

Treated sanitary and domestic wastes may have a slight transient effect on water quality in the immediate vicinity of these discharges. NPDES permit limitations and requirements will be met and little or no impact on water quality is anticipated.

Deck drainage includes all effluents resulting from rain, deck washings, and runoff from curbs, gutters, and drains, including drip pans in work areas. Rainwater that falls on uncontaminated areas of the drilling rig will flow overboard without treatment. However, rainwater that falls on the drilling rig deck and other areas such as chemical storage areas and places where equipment is exposed will be collected and oil and water separated to meet NPDES permit requirements. Little or no impact on water quality is anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water are expected to be diluted rapidly and have little or no impact on water quality.

Support vessels will discharge treated sanitary and domestic wastes. These will have a slight effect on water quality in the immediate vicinity of the discharges. Support vessel discharges will be in accordance with USCG regulations and, as applicable, the NPDES Vessel General Permit, and therefore are not expected to cause significant impacts on water quality.Impacts of a Small Fuel Spill

Potential impacts of a small spill on water quality are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b, 2008b). The probability of a small spill would be minimized by Shell’s preventative measures during routine operations, including fuel transfer. In the unlikely event of a spill, implementation o f Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the extent and duration of water quality impacts from a small spill would not be significant.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. However, it is estimated that more than 90% of a small diesel spill would be evaporated or dispersed within 24 hours (see

Section A.9.2 ). The area of the sea surface with diesel fuel on it would range from 1.2 to

12 acres (0.5 to 5 ha) depending on sea state and weather conditions.

The water-soluble fractions of diesel are dominated by two- and three-ringed PAHs, which are moderately volatile (NRC, 2003). The constituents of these oils are light to intermediate in molecular weight and can be readily degraded by aerobic microbial oxidation. Diesel’s density is such that it will not sink and pool on the seafloor. Diesel dispersed in the water column can adhere to suspended sediments, but this generally occurs only in coastal areas with high-suspended solid loads (NRC, 2003) and would not be expected to occur to any appreciable degree in offshore waters of the Gulf of Mexico. Diesel oil is readily and completely degraded by naturally occurring microbes (NOAA, 2006).

A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill

Potential impacts of a large oil spill on water quality are expected to be consistent with those analyzed and discussed in recent EISs (MMS, 2007b, 2008b). A large spill would affect water quality by producing a slick on the water surface and increasing the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Most of the oil would be expected to form a slick at the surface, although new information from the Macondo spill indicates that plumes of submerged oil droplets can be produced when subsea dispersants are applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). A report by Kujawinski et al. (2011) indicates that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and were detectable up to 186 miles (300 km) from the wellsit e at a water depth of 3,280 to 3,937 ft (1,000 to 1,200 m).

Once oil enters the ocean, a variety of physical, chemical, and biological processes act to disperse the oil slick. These processes include spreading, evaporation of the more volatile constituents, dissolution into the water column, emulsification of small droplets, agglomeration sinking, microbial modification, photochemical modification, and biological ingestion and excretion (NRC, 2003). Marine water quality would be temporarily affected by the dissolved components and small oil droplets that do not rise to the surface or are mixed down by surface turbulence. Dispersion by currents and microbial degradation removes the oil from the water column or dilutes the constituents to background levels.A large oil spill could result in a release of gaseous hydrocarbons that could affect water quality. During the Macondo spill, large volumes of methane (CH 4 ) were released, causing localized oxygen depletion as methanotrophic bacteria rapidly metabolized the hydrocarbons (Joye et al., 2011; Kessler et al., 2011). However, a broader study of the deepwater Gulf of Mexico found that although some stations had slightly depressed dissolved oxygen concentrations relative to climatological background values, concentrations were not low enough to indicate hypoxia (<2.0 mg/L) (OSAT, 2010). Stations revisited around the Macondo wellhead in October 2010 showed no measurable oxygen depression (OSAT, 2010).

Due to the lease area location (75 miles [120 km] from the nearest shoreline), most water quality impacts would occur in offshore waters. Depending on the spill trajectory and the effectiveness of spill response measures, coastal water quality could be affected. Based on the OSRA modeling predictions ( Table 18. 3 ), nearshore waters and embayments of Plaquemines Parish, Louisiana, are the most likely coastal areas where water quality could be affected.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an

event will be m inimized by Shell’s well control and blowout prevention measures detailed in

SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on water quality are expected.

C.2 Seafloor Habitats and Biota

Water depths at the proposed well surface locations range from 7,301 to 7,385 ft (2,225 to 2,251 m). The seafloor at the wellsites is expected to consist mainly of soft bottom. The chemosynthetic community assessment based on the hazards report by AOA Geophysics, Inc. (2004) and Fugro Geoservices, Inc. (2007, 2009b and 2011) did not identify any features that could support high-density deepwater benthic communities within 2,000 ft (610 m) of the

wellsites. See SEP Section 6a for further information.

According to the BOEMRE (2011), existing information for the deepwater Gulf of Mexico indicates that the seafloor is composed primarily of soft sediments; hard bottom communities are rare. MC 393 is within deepwater Grid 16, and the BOEM website indicates that remotely operated vehicle (ROV) coverage of the seafloor in this grid is adequate to characterize the area (BOEMRE, 2011).

C.2.1 Soft Bottom Benthic Communities

Data from the recent Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology study (Wei, 2006; Rowe and Kennicutt, 2009) can be used to describe typical benthic

communities in the area. Table 18. 4 summarizes data from two nearby stations in similar water depths. Sediments at those two stations were predominantly clay (51% to 57%) and silt (35% to 41%).

Table 18. 4. Benthic community data from stations near the lease area and in similar water

depths sampled during the Northern Gulf of Mexico Continental Slope Habitats and Benthic Ecology Study (From: Wei, 2006; Rowe and Kennicutt, 2009).

Station Location

Relative to

Lease Area Water

Depth (m) Abundance

Meiofauna (individuals/m 2 ) Macroinfauna

(individuals/m 2 ) Megafauna

(i ndividuals/ha)

S

- 37 12 mi SE 2,384 291,179 2,192 1,451

S

- 36 27 mi NE 1,828 799,963 4,481 359

Meiofaunal and megafaunal abundance from Rowe and Kennicutt (2009); macroinfaunal abundance from Wei (2006).Meiofauna (animals passing through a 0.5-mm sieve but retained on a 0.062-mm sieve) densities in water depths representative of the lease area typically range from about 120,000 to 290,000 individuals/m 2 (Rowe and Kennicutt, 2009). Nematodes, nauplii, and harpacticoid copepods were the three dominant groups in the meiofauna, accounting for about 90% of total

abundance.

The benthic macroinfauna is characterized by small mean individual sizes and low densities, both of which are a reflection of the meager primary production in Gulf of Mexico surface waters (Wei, 2006). Densities decrease exponentially with water depth. Based on an equation presented by Wei (2006), macroinfaunal densities in the water depths of the wellsites are expected to be about 1,300 individuals/m 2 , lower than the values in Table 18.4

.

Polychaetes are typically the most abundant macroinfaunal group on the northern Gulf of Mexico continental slope, followed by amphipods, tanaids, bivalves, and isopods. Wei (2006) recognized four depth-dependent faunal zones (1 through 4), two of which are divided horizontally. The lease area is in Zone 2E, which consists of stations on the mid Texas-Louisiana slope, west flank of the Mississippi Fan, mid Mississippi Canyon, head of De Soto Canyon and mid West Florida Terrace. These stations range in depth from 2,051 to 5,997 ft (625 to 1,828 m). The five most abundant species in Zone 2E were the polychaetes Litocorsa antennata, Aricidea suecica,Tharyx marioni, Paralacydonia paradoxa, and one bivalve Heterodonta sp.

Megafaunal density from nearby stations S-37 and S-36 was 1,451 and 359 individuals/ha, respectively ( Table 18. 4 ). Densities of 250 to 1,600 individuals/ha were reported from other stations in a similar depth range. Common megafauna included motile groups such as decapods, ophiuroids, holothurians, and demersal fishes, as well as sessile groups such as sponges and

anemones.

Bacteria are also an important component in terms of biomass and cycling of organic carbon (Cruz-Kaegi, 1998). Bacterial biomass at the depth range of the lease area typically is about

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

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

Impacts of Physical Disturbance to the Seafloor

There will be minimal disturbance to soft bottom communities on the seafloor during positioning and anchoring of the semisubmersible Transocean Deepwater Nautilus. Shell is proposing anchor radii of 15,500 ft (4,724 m) for the wellsites; the total anchor clearance radius will be 16,500 ft (5,029 m). Cables may initially be laid on the seafloor anywhere within the anchor radius (except for avoidance zones based on the hazards survey as detailed in SEP Section 6a ). According to the MMS (2007b) semisubmersible rigs disturb about 5-7 ac (2-3 ha), depending on their mooring configurations. The total seafloor disturbance area is estimated to be 35 ac (15 ha) for the six wellsites (five surface locations). During anchor deployment, cables will be resting on the seafloor only during the pre- and post-installation phase; once the rig arrives on location, cables are pulled taut towards the rig. The cables do not sweep the seafloor or cross any sensitive features, and therefore they are expected to have little or no physical impact on benthic

communities.

The seafloor in the project area is expected to consist of soft bottom benthic habitat. Small anchor and/or cable scars created during the project will likely remain on the bottom for months to years (Shinn et al., 1993). In a recent study of drillsites on the Gulf of Mexico continentalslope, Continental Shelf Associates, Inc. (2006) detected anchor scars up to 14 years after drilling was completed. These features will eventually disappear as sediments are redistributed by currents and benthic organisms.

Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway et al., 2003; Rowe and Kennicutt, 2009). Physical disturbance to the seafloor during this project will have no significant impact on soft bottom benthic communities on a regional

basis.

Impacts of Effluent Discharges

Drilling mud and cuttings are the only effluents that are likely to affect benthic communities. During initial well interval(s) before the marine riser is set, cuttings and seawater- based “spud
mud” will be released at the seafloor. Excess cement slurry will also be released at the seafloor during casing installation for the riserless portion of the drilling operations. Cement slurry components typically include cement mix and some of the same chemicals used in water-based drilling mud (Boehm et al., 2001). The main impacts will be burial and smothering of benthic organisms within several meters to tens of meters around the wellbore. Soft bottom sediments disturbed by cuttings, drilling mud, and cement slurry will eventually be recolonized through larval settlement and migration from adjacent areas. Because some deep-sea biota grow and reproduce slowly, recovery may require several years.

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

The areal extent of impacts from drilling discharges will be small; the typical effect radius is 1,640 ft (500 m) around each wellsite. For the five surface locations in this exploration-drilling program, the total impact area would be 970 acres (390 ha). Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope (Gallaway, 1988; Gallaway et al., 2003; Rowe and Kennicutt, 2009). Impacts from drilling discharges during this project will have no significant impact on soft bottom benthic communities on a regional basis.

Impacts of a Large Oil Spill

The most likely effects of a subsea blowout on benthic communities would be within a few hundred meters of the wellsites. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 984-ft (300-m) radius. While coarse sediments (sands) would probably settle at a rapid rate within 1,312 ft (400 m) from the blowout site, fine sediments (silts and clays) could be resuspended for more than 30 days and dispersed over a much wider area. Previous studies characterized surface sediments in the vicinity of the site as about 50% clay and 45% silt (Rowe and Kennicutt, 2009).Previous analyses (MMS, 2007a, 2008b) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsites and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). This observation is supported by Kujawinski et al. (2011) in their report that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and were detected up to 186 miles (300 km) from the wellsite at a water depth of 3,280 to 3,937 ft (1,000 to 1,200 m). However, estimated dispersant concentrations in the subsea plume were below levels known to be toxic to marine life. While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 984-ft (300- m) radius estimated by MMS (2007a, 2008b), depending on its extent, trajectory, and persistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (NRC, 2003).

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an

event will be min imized by Shell’s well control and blowout prevention measures as detailed in

SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on soft bottom communities are expected.

C.2.2 High-Density Deepwater Benthic Communities

As defined by NTL 2009-G40, high-density deepwater benthic communities are features or areas that could support high-density chemosynthetic communities, high-density deepwater corals, or other associated high-density hard bottom communities. Chemosynthetic communities were discovered in the central Gulf of Mexico in 1984 and have been studied extensively (MacDonald,

20 02). Deepwater coral communities are also known from numerous locations in the Gulf of Mexico (Brooke and Schroeder, 2007; CSA International, Inc., 2007). These communities occur almost exclusively on authigenic carbonates created by chemosynthetic communities, and on shipwrecks.

The chemosynthetic community assessment included in this SEP, based on the shallow hazards reports by AOA Geophysics, Inc. (2004) and Fugro Geoservices, Inc. (2007, 2009b & 2011), did not identify any features that could support high-density deepwater benthic communities within 2,000 ft (610 m) of the proposed drilling mud/cuttings discharge locations.

IPFs potentially affecting high-density deepwater benthic communities are effluent discharges (drilling mud and cuttings), and a large oil spill from a well blowout at the seafloor. A small fuel spill would not affect benthic communities because the diesel fuel would float and dissipate on

the sea surface.

Impacts of Physical Disturbance to the Seafloor

Features or areas that could support high-density benthic communities are not located within 250 ft (76 m) of any areas where seafloor disturbance may result from the use of anchors (including those caused by anchors, anchor chains, and wire ropes ) (AOA Geophysics, Inc., 2004; Fugro Geoservices, Inc., 2007, 2009b, 2011).

Impacts of Effluent Discharges

The chemosynthetic community assessment included in this SEP, based on the shallow hazards reports by AOA Geophysics, Inc. (2004) and Fugro Geoservices, Inc. (2007, 2009b, 2011), didnot identify any features that could support high-density deepwater benthic communities within 2,000 ft (610 m) of the proposed drilling mud/cuttings discharge locations. Monitoring programs on the Gulf of Mexico continental slope have shown that benthic impacts from drilling discharges typically are concentrated within about 1,640 ft (500 m) of the wellsites, although detectable deposits may extend beyond this distance (Continental Shelf Associates, Inc., 2004, 2006;

Neff et al., 2005). If high-density deepwater communities are associated with the more distant expulsion features and mud volcanoes identified in the hazards survey, significant impacts on these communities will be avoided because of the distance from the discharge location.

Impacts of a Large Oil Spill

Previous analyses (MMS, 2007a, 2008b) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsites and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). This observation is supported by Kujawinski et al. (2011) in their report that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and were detectable up to 186 miles (300 km) from the wellsite at a water depth of 3,280 to 3,937 ft (1,000 to 1,200 m). However, estimated dispersant concentrations in the subsea plume were below levels known to be toxic to marine life. While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact high-density deepwater benthic communities beyond the 984-ft (300-m) radius estimated by MMS (2007a, 2008b), depending on its extent, trajectory, and persistence. Potential impacts on sensitive resources would be an integral part of the decision and approval process for the use of dispersants.

Potential impacts of oil on high-density deepwater benthic communities are discussed by

MMS (2007b). Although chemosynthetic communities live among hydrocarbon seeps, natural seepage is very constant and occurs at low rates compared to the potential rates of oil release from a blowout. In addition, seep organisms require unrestricted access to oxygenated water at the same time as exposure to hydrocarbon energy sources (MacDonald, 2002). Oil droplets or oiled sediment particles could come into contact with chemosynthetic organisms or deepwater corals. As discussed by MMS (2007b), impacts could include loss of habitat, biodiversity, and live coral coverage; destruction of hard substrate; change in sediment characteristics; and reduction or loss of one or more commercial and recreational fishery habitats. Sublethal effects could be long lasting and affect the resilience of coral colonies to natural disturbances (e.g., elevated water temperature and diseases).

The potential for a spill to affect deepwater corals is indicated by preliminary findings from an October 2010 survey of deepwater coral habitats near the Macondo spill site (BOEMRE, 2010). Government and academic researchers working at a site 4,600 ft (1,400 m) deep and approximately 7 miles (11 km) southwest of the Macondo wellhead observed dead and dying corals with sloughing tissue and discoloration. The study location was about 29 miles (47 km) from the lease area. Much of the soft coral observed in an area measuring about 50 to 130 ft (15 to 40 m) was covered by what appeared to be a brown substance. Ninety percent of

40 large corals were heavily affected and showed dead and dying parts and discoloration. Another site 1,312 ft (400 m) away had a colony of stony corals similarly affected and partially covered with a similar brown substance. Until laboratory analyses are conducted, scientists cannot be certain what caused the impacts. Sediment and coral samples were collected with an ROV and brought to the surface for analyses. Further testing will also determine if the substance

is oil, and if so, whether it is consistent with the release from the Macondo spill.A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention mea sures as detailed in

SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on deepwater benthic communities are expected.

C.2.3 Designated Topographic Features

The block is not within or near a designated topographic feature or a no-activity zone as identified in NTL 2009-G39. The nearest designated topographic feature is in the West Delta Area, South Addition Block 147 , located 94 miles (151 km) west of the lease area.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

C.2.4 Pinnacle Trend Area Live Bottoms

The lease area is not covered by the Live Bottom (Pinnacle Trend) Stipulation. As defined by NTL 2009-G39, the nearest pinnacle trend blocks are about 43 miles (69 km) from the lease area, along the shelf edge south of Alabama.

There are no IPFs associated with either routine operations or accidents that could cause impacts to pinnacle trend area live bottoms due to the distance from the lease area. A small fuel spill

would float on the surface and would not reach these seafloor features.

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

C.2.5 Eastern Gulf Live Bottoms

The lease area is not covered by the Live Bottom (Low-Relief) Stipulation, which applies to Eastern Gulf of Mexico Planning Area leases in water depths of 328 ft (100 m) or less. The nearest blocks covered by the live bottom stipulation, as defined by NTL 2009-G39, are abou t

54 miles (86 km) from the project area.

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

In the event of an oil spill from a well blowout, a surface slick would not contact these seafloor features. If a subsurface plume were to occur, impacts on these features would be unlikely due to the distance and the difference in water depth. Near-bottom currents in the region are predicted to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf.C.3 Threatened, Endangered, and Protected Species and Critical Habitat

This section discusses species listed as endangered or threatened under the ESA. In addition, it includes all marine mammal species in the region, which are protected under the MMPA.

Endangered or threatened species that may occur in the project area and/or along the northern
Gulf Coast are listed in Table 18. 5 . The table also indicates the location of critical habitat (if designated in the Gulf of Mexico). Critical habitat is defined as (1) specific areas within the geographical area occupied by the species at the time of listing, if they contain physical or biological features essential to conservation, and those features may require special management considerations or protection; and (2) specific areas outside the geographical area occupied by the species if the agency determines that the area itself is essential for conservation. The NMFS has jurisdiction over ESA-listed cetaceans, sea turtles, and fishes in the Gulf of Mexico. The USFWS has jurisdiction over ESA-listed birds and the Florida manatee.

The sperm whale and five species of sea turtles are the only endangered or threatened species likely to occur at or near the lease area. No critical habitat has been designated for these species

in the Gulf of Mexic o.

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

in the Gulf of Mexico.

Coastal endangered or threatened species include the Florida manatee, Piping Plover, Whooping Crane, Gulf sturgeon, and four subspecies of beach mouse. Critical habitat has been designated for all of these species as indicated in Table 18. 5 and discussed in individual

sections.

Table 18.5 Federally-listed endangered and threatened species in the lease area and along

the northern Gulf Coast.

Species Scientific Name Status Potential
Presence Criti cal Habitat

Designated in Gulf of Mexico Lease
Area Coastal

Marine Mammals Sperm whale Physeter macrocephalus E X

-- None

Florida manatee Trichechus manatus latirostris E

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

-- None
Fi n whale Balaenoptera physalus E X a

-- None Humpback whale Megaptera novaeangliae E X a

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

-- None
Sei whale Balaenoptera borealis E X a

-- None
Sea Turtles Loggerhead turtle Caretta caretta T , E b X X None

Green turtle Chelonia mydas T, E c X X None
Leatherback turtle Dermochelys coriacea E X X None
Hawksbill turtle Eretmochelys imbricata E X X None Kemp’s ridley turtle Lepidochelys kempii E X X None

### Table 18.5 (Continued.)

Species Scientific Name Status Potential
Presence Criti cal Habitat

Designated in Gulf of Mexico Lease
Area Coastal

Birds

Piping Plover Charadrius melodus T

-- X Coastal Texas, Louisiana, Mississippi, Alabama, and Florida (Panhandle)

Whooping Crane Grus americana E

-- X Coastal Texas (Aransas National Wildlife Refuge)
Fishes

Gulf sturgeon Acipenser oxyrinchus desotoi T

-- X Coastal Louisiana, Mississippi, Alab ama, and Florida (Panhandle)
Terrestrial Mammals
Beach m ouse (A labama, Choctawhatchee,
Perdido Key,
St. Andrew) Peromyscus polionotus E

-- X Alabama and Florida (Panhandle) beaches

Abbreviations: E = Endangered; T = Threatened.
a The blue, fin, humpback, North Atlantic right, and sei whales are rare or extralimital in the Gulf of Mexico and are
unlikely to be present in the lease area.
b The loggerhead turtle is composed of nine distinct population segments (DPS) that are considered “species.” The

on ly DPS that may occur in the project area (Northwest Atlantic DPS) is listed as threatened ( 76 FR 58868; September 22, 2011).
c The green sea turtle is threatened, except for the Florida breeding population, which is listed as endangered.

Two other coastal species (Bald Eagle and Brown Pelican) discussed by MMS (2007b) are no longer listed as endangered or threatened; these are discussed under Coastal and Marine Birds.

There are no other endangered animals or plants in the Gulf of Mexico that are reasonably likely to be affected by either routine or accidental events. Other species occurring at certain locations in the Gulf of Mexico such as the smalltooth sawfish ( Pristis pectinata ), elkhorn coral (

Acropora palmata ), staghorn coral (

Acropora cervicornis

), and Florida salt marsh vole ( Microtus pennsylvanicus dukecampbelli ) are remote from the lease area and highly unlikely to be affected.

C.3.1 Sperm Whale (Endangered)

The only endangered marine mammal likely to be present at or near the project area is the sperm whale ( Physeter macrocephalus ). Resident populations of sperm whales occur within the Gulf of Mexico. A species description is presented in a recent lease sale EIS (MMS, 2007b). Gulf of Mexico sperm whales are classified as an endangered species and a “strategic stock” (defined as a stock that may have unsustainable human-caused impacts) by NMFS (Waring et al., 2009). No critical habitat for the sperm whale has been designated in the Gulf of Mexico.

The distribution of sperm whales in the Gulf of Mexico is correlated with mesoscale physical features such as eddies associated with the Gulf of Mexico Loop Current (Jochens et al., 2008). Sperm whale populations in the north-central Gulf of Mexico are present there throughout the year (Davis et al., 2000). Results of a multi-year tracking study show female sperm whales typically concentrated along the upper continental slope between the 656- and 3,280-ft (200- and 1,000-m) depth contours (Jochens et al., 2008). Male sperm whales were more variable in their movements and were documented in water depths greater than 9,483 ft (3,000 m). Generally, groups of sperm whales sighted in the Gulf of Mexico during the

MMS -funded Sperm Whale Seismic Study (SWSS) consisted of mixed-sex groups comprising adultfemales and immatures, and groups of bachelor males. Typical group size for mixed groups was

10 individuals (Jochens et al., 2008). SWSS results show that sperm whales transit through the vicinity of the lease area. Movements of satellite-tracked individuals suggest that this area of the Gulf continental slope is within the home range of the Gulf of Mexico population (within the 95% utilization distribution) (Jochens et al., 2008).

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

– a small fuel spill and a large oil spill. Effluent discharges are likely to have negligible impacts on sperm whales due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these marine mammals. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on sperm whales.

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb sperm whales. Sperm whales appear to have good low-frequency hearing, but the available data do not indicate a consistent response to anthropogenic noise (Jochens et al., 2008). Noise associated with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be transient. There are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar sources. Due to the limited scope, timing, and geographic location of drilling activities, this project would represent a small temporary contribution to the overall noise regime.

The NMFS (2007) analyzed the potential for impacts of drilling-related noise on sperm whales in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. The analysis noted that drilling rigs show low sound source levels and concluded that drilling is not expected to produce amplitudes sufficient to cause hearing or behavioral effects in sperm whales; therefore, these effects are insignificant (NMFS, 2007).

Although drilling rig lighting and rig presence were considered potential factors affecting sperm whales, NMFS’s 2007 Biological Opinion and recent lease sale EISs (MMS, 2007b, 2008b) did not identify rig lighting and presence as IPFs for sperm whales.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sperm whales, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (NMFS, 2010a). Data concerning the frequency of vessel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, the BOEM has issued NTL 2007-G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When whales are sighted, vessel operators and crews are required to attempt to maintain a distance of 300 ft (91 m) or greater whenever possible. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel when safety permits. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sperm

whales.

The NMFS (2007) analyzed the potential for vessel strikes and harassment of sperm whales in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. With implementation of the mitigation measures in NTL 2007-G04, NMFS concluded that the likelihood of collisions between vessels and sperm whales would be reduced to insignificant levels. The NMFS concluded that the observedavoidance of passing vessels by sperm whales is an advantageous response to avoid a potential threat and is not expected to result in any significant effect on migration, breathing, nursing,

bre eding, feeding, or sheltering to individuals, or have any consequences at the level of the population. With implementation of the vessel strike avoidance measures requirement to maintain a distance of 300 ft (91 m) from sperm whales, the NMFS concluded that the potential for harassment of sperm whales would be reduced to discountable levels.

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

24 sightings (12%). All three reactions consisted of a hasty dive and occurred at less than 1,180 ft (360 m) lateral distance from the aircraft. Additional reactions were seen when aircraft circled certain whales to make further observations. Based on other studies of cetacean responses to sound, the authors concluded that the observed reactions to brief overflights by the aircraft wer e short-term and probably of no long-term biological significance.

While flying offshore in the Gulf of Mexico, helicopters maintain altitudes above 700 ft (213 m) during transit to and from the working area. In the event that a whale is seen during transit, the helicopter will not approach or circle the animals. Although responses are possible based on the Smultea et al. (2008) study, the NMFS (2007) concluded that this altitude would minimize the potential for disturbing sperm whales. Therefore, no significant impacts are expected.

Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs (MMS, 2007b, 2008b) and by the NMFS (2007) in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this SEP there are no unique site-specific issues with respect to spill impacts on these animal s.

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts on sperm whales. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (Marine Mammal Commission [MMC], 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of sperm whales, no significant impacts would be expected.

Impacts of a Large Oil Spill

Potential spill impacts on marine mammals including sperm whales are discussed in recent EISs (MMS, 2007b, 2008b) and by the NMFS (2007) in its Biological Opinion for the Five-Year Oil andGas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. Oil impacts on marine mammals are discussed by Geraci and St. Aubin (1990). For this SEP, there are no unique site-specific issues with respect to spill impacts on these animals.

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

Studies have shown that the cetacean epidermis functions as an effective barrier to noxious substances found in petroleum (Geraci and St. Aubin, 1985). Unlike other mammals, penetration of such substances in cetacean skin is impeded by tight intercellular bridges, the vitality of the superficial cells, the thickness of the epidermis, and the lack of sweat glands and hair follicles. In addition, cetacean skin is free from hair or fur, which in other marine mammals not found in the Gulf of Mexico (e.g., pinnipeds and otters) tends to collect oil and/or tar.

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sperm whales and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the potential for striking or disturbing these animals.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on sperm whales are expected.

C.3.2 Florida Manatee (Endangered)

Most of the manatee population is located in peninsular Florida (USFWS, 2001). Manatees regularly migrate farther west of Florida in the warmer months (Wilson, 2003) into Alabama and Louisiana coastal environs, with some individuals traveling as far as west Texas (Fertl et al., 2005). A species description is presented in a recent lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS, 2001).

IPFs potentially affecting manatees include support vessel and helicopter traffic and a large oil spill. A small fuel spill in the lease area would be unlikely to affect manatees, as the lease area is approximately 75 miles (120 km) from the nearest shoreline (Louisiana). As explained in

Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on manatees.

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb manatees, and there is also a risk of vessel strikes, which are identified as a threat in the recovery plan for this species (USFWS, 2001). To reduce the potential for vessel strikes, the BOEM has issued NTL 2007-G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilantwatch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Compliance with this NTL will minimize the likelihood of vessel strikes, and no significant impacts on manatees are expected.

Helicopter traffic, if present, also has the potential to disturb manatees. Rathbun (1988) reported that manatees were disturbed more by helicopters than by fixed-wing aircraft; however, the helicopter was flown at a relatively low altitude of 66 to 525 ft (20 to 160 m). Helicopters used in support operations maintain a minimum altitude of 700 ft (213 m) while in transit offshore, 1,000 ft (305 m) over unpopulated areas or across coastlines, and 2,000 ft (610 m) over populated areas and sensitive habitats such as wildlife refuges and park properties. This mitigation measure will minimize the potential for disturbing manatees, and no significant impacts are expected.

Impacts of a Large Oil Spill

The OSRA results summarized in Table 18. 3 predict that some Louisiana, Mississippi, Alabama, and Florida shorelines could be contacted by a spill within 30 days. There is no critical habitat designated in these areas, and the number of manatees potentially present is a small fraction of the population in peninsular Florida.

In the event that manatees were exposed to oil, effects could include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

In the event that a large spill reached coastal waters where manatees were present, the level of vessel and aircraft activity associated with spill response could disturb manatees and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event o f a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on manatees are expected.

C.3.3 Endangered Mysticete Whales

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

in the Gulf of Mexico.

Due to the rare occurrence of these whales in the Gulf of Mexico and the limited scope and duration of the project, it is highly unlikely that any endangered mysticete would come into contact with any project activities, either routine operations or accidents. The NMFS (2007) didnot include any of these mysticete whales as affected species in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in the Central and Western Planning Areas of the Gulf of Mexico. Potential impacts are analyzed in recent lease sale EISs (MMS, 2007b, 2008b), and those analyses are incorporated by reference. If any of these whales were present in the area, potential impacts would be the same as those discussed below in Section C.3.4

.

C.3.4 Non-Endangered Marine Mammals (Protected)

In addition to the seven endangered species that have been cited previously, 22 other species of marine mammals occur in the Gulf of Mexico, including two mysticete whales, the dwarf and pygmy sperm whales, 4 species of beaked whales, and 14 species of delphinids (see SEP Section 6h ). All marine mammals are protected species under the MMPA. The most common non-endangered cetaceans in the deepwater environment are odontocetes such as the pantropical spotted dolphin, spinner dolphin, and clymene dolphin. A brief summary is presented below, and additional information on these groups is presented in a recent lease sale EIS (MMS, 2007b).

Mysticete whales . Two non-endangered mysticete whales are known from the Gulf of Mexico. The Bryde’s whale ( Balaenoptera edeni ) has been sighted most frequently along the 328-ft (100-m) isobath (Davis and Fargion, 1996; Davis et al., 2000). Most sightings have been made in the De Soto Canyon region and off western Florida, although there have been some in the west-central portion of the northeastern Gulf. The minke whale ( Balaenoptera acutorostrata ) is considered rare in the Gulf of Mexico, with the only confirmed records coming from strandings (Würsig et al., 2000). Based on the available data, it is possible that Bryde’s whales could occur

in the lease area.

Dwarf and pygmy sperm whales . At sea, it is difficult to differentiate dwarf sperm whales ( Kogia sima

) from pygmy sperm whales ( Kogia breviceps ), and sightings are often grouped together as “ Kogia spp.” Both species have a worldwide distribution in temperate to tropical waters. In the Gulf of Mexico, both species occur primarily along the continental shelf edge and in deeper waters off the continental shelf (Mullin et al., 1991; Mullin, 2007). Either species could

occur in the lease area.

Beaked whales . Four species of beaked whales are known from the Gulf of Mexico. They are Blainville’s beaked whale ( Mesoplodon densirostris ), Cuvier’s beaked wh ale ( Ziphius cavirostris ), Sowerby’s beaked whale ( Mesoplodon bidens ), and Gervais’ beaked whale ( Mesoplodon

europaeus

). Stranding records in the Gulf of Mexico suggest that Gervais’ beaked whale is the most common and Sowerby’s beaked whale is extralimit al. Due to the difficulties of at-sea identification, beaked whales in the Gulf of Mexico are identified either as Cuvier’s beaked whales or are grouped into an undifferentiated complex ( Mesoplodon spp. and Ziphius spp.). In the northern Gulf of Mexico, they are broadly distributed in waters greater than 3,281 ft (1,000 m) over lower slope and abyssal landscapes (Davis et al., 2000). Any of these species could occur in

the lease area.

Delphinids . Fourteen species of delphinids are known from the Gulf of Mexico, including Atlantic spotted dolphin ( Stenella frontalis ), bottlenose dolphin ( Tursiops truncatus

), clymene dolphin ( Stenella clymene

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

hosei ), killer whale ( Orcinus orca ), melon-headed whale ( Peponocephala electra ), pantropical spotted dolphin ( Stenella attenuata ), pygmy killer whale ( Feresa attenuata ), short

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

- toothed dolphin ( Steno breda

nensis ), spinner dolphin ( Stenella longirostris ), and striped dolphin ( Stenella

coeruleoalba

). The most common non

- endangered cetaceans in the deepwater environment are the pantropical spotted dolphin, spinner dolphin, and clymene dolphin. However, any o f these species could occur in the lease area.IPFs potentially affecting non-endangered marine mammals include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill). Effluent discharges are likely to have negligible impacts on marine mammals due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of marine mammals. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on marine mammals.

Impacts of Drilling Rig Presence, Noise, and Lights

Noise from routine drilling activities has the potential to disturb marine mammals. Most odontocetes (toothed whales and dolphins) use sounds that are higher than the low-frequency dominant frequencies produced by OCS drilling activities (Richardson et al., 1995). Noise associated with drilling is relatively weak in intensity, and an individual animal’s noise exposure would be transient. There are other OCS facilities and activities near the lease area, and the region as a whole has a large number of similar sources. Due to the limited scope, timing, and geographic extent of drilling activities, this project would represent a small temporary contribution to the overall noise regime, and any short-term impacts are not expected to be biologically significant to marine mammal populations.

Drilling rig lighting and rig presence are not identified as IPFs for marine mammals in recen t lease sale EISs (MMS, 2007b, 2008b).

Impacts of Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb marine mammals, and there is also a risk of vessel strikes. Data concerning the frequency of vessel strikes is presented in the lease sale EIS (MMS, 2007b). To reduce the potential for vessel strikes, the BOEM has issued NTL 2007-G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for marine mammals and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. Vessel operators and crews are required to attempt to maintain a distance of 300 ft (91 m) or greater when whales are sighted and 150 ft (45 m) when small cetaceans are sighted. When cetaceans are sighted while a vessel is underway, vessels must attempt to remain parallel to the animal’s course and avoid excessive speed or abrupt changes in direc tion until the cetacean has left the area. Vessel operators are required to reduce vessel speed to 10 knots or less when mother/calf pairs, pods, or large assemblages of cetaceans are observed near an underway vessel, when safety permits. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing marine mammals, and therefore no significant impacts are expected.

Aircraft traffic also has the potential to disturb marine mammals (Würsig et al., 1998). However, while flying offshore, helicopters maintain altitudes above 700 ft (213 m) during transit to and from the working area. This altitude will minimize the potential for disturbing marine mammals, and no significant impacts are expected (MMS, 2007b ).

Impacts of a Small Fuel Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008b), and oil impacts on marine mammals in general are discussed by Geraci and St. Aubin (1990). For this SEP, there are no unique site-specific issues with respect to spill impacts on these

animals.

The probability of a fuel spill will be minimized by Shell’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP is expected to mitiga te and reduce the potential for impacts on marine mammals. SEP Sections 2j and 9b providedetail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, as well as the mobility of marine mammals, no significant impacts would be expected.

Impacts of a Large Oil Spill

Potential spill impacts on marine mammals are discussed in recent EISs (MMS, 2007b, 2008b) and by Geraci and St. Aubin (1990). For this SEP, there are no unique site-specific issues.

Impacts of oil spills on marine mammals can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants) (MMC, 2010). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil (and dispersants) directly or via contaminated prey (or contaminated vegetation, in the case of manatees); and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing prey availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010).

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb marine mammals and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implemen tation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on marine mammals are expected.

C.3.5 Sea Turtles (Endangered/Threatened)

As listed in SEP Section 6h , five species of endangered or threatened sea turtles may be found near the lease area. Endangered species are the leatherback ( Dermochelys coriacea ), Kemp's ridley ( Lepidochelys kempii ), and hawksbill ( Eretmochelys imbricata ) turtles. The loggerhead turtle ( Caretta caretta

) is a threatened species. The green turtle ( Chelonia mydas ) is listed as threatened, except for the Florida breeding population, which is listed as endangered. Species descriptions are presented in a recent lease sale EIS (MMS, 2007b).Leatherbacks and loggerheads are the most likely species to be present near the lease area as adults. Green, hawksbill, and Kemp’s ridley turtles are typically inner shelf and nearshore species, unlikely to occur near the lease area as adults. Hatchlings or juveniles of any of the sea turtles may be present in deepwater areas, including the lease area, where they may be

associated with Sargassum and other flotsam.

All five sea turtle species in the Gulf of Mexico are migratory and use different marine habitats according to their life stage. These habitats include high-energy beaches for nesting females and emerging hatchlings and pelagic convergence zones for hatchling and juvenile turtles. As adults, green, hawksbill, and loggerhead turtles forage primarily in shallow, benthic habitats. Leatherbacks are the most pelagic of the sea turtles, feeding primarily on jellyfish.

Sea turtle nesting in the northern Gulf of Mexico can be summarized by species as follows:

Loggerhead turtles

–

Loggerheads nest in significant numbers along the Florida Panhandle and, to a lesser extent, from Texas through Alabama (MMS, 2007b). The nearest significant nesting area of loggerhead turtles is found in Louisiana, on beaches within the Breton NWR;

Green and leatherback turtles

– Green and leatherback turtles infrequently nest on Florida Panhandle beaches (Florida Fish and Wildlife Conservation Commission, 2011); Kemp’s ridley turtles – The main Kemp’s ridley nesting site is Rancho Nuevo beach, Tamaulipas,

Me xico (NMFS et al., 2010). Approximately 200 Kemp’s ridley turtles nested on Texas beaches in 2009 (Sea Turtle Restoration Project, 2011). Kemp’s ridley turtles typically do not nest anywhere near the project area, although there have been occasional repo rts of Kemp’s ridleys nesting in Alabama (Share the Beach, 2010); and

Hawksbill turtles

–

Hawksbills typically do not nest anywhere near the project area.

IPFs potentially affecting sea turtles include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill). Effluent discharges are likely to have negligible impacts on sea turtles due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on sea turtles.

Impacts of Drilling Rig Presence, Noise, and Lights

Offshore drilling activities produce a broad array of sounds at frequencies and intensities that may be detected by sea turtles (Geraci and St. Aubin, 1987). Potential impacts may include behavioral disruption and temporary or permanent displacement from the area near the sound source. Certain sea turtles, especially loggerheads, may be attracted to offshore structures (Lohoefener et al., 1990) and, thus, may be more susceptible to impacts from sounds produced during routine operations. Helicopters and service vessels may also affect sea turtles due to machinery noise and/or visual disturbances. The most likely impacts would be short-term behavioral changes such as diving and evasive swimming, disruption of activities, or departure from the area. Due to the limited scope, timing, and geographic extent of drilling activities, these short-term impacts are not expected to be biologically significant to sea turtle populations.

Artificial lighting can disrupt the nocturnal orientation of sea turtle hatchlings (Witherington, 1997; Tuxbury and Salmon, 2005). However, hatchlings may rely less on light cues when they are offshore than when they are emerging on the beach (Salmon and Wyneken, 1990). The NMFS (2007) concluded that the effects of lighting from offshore structures on sea turtles are insignificant.

Support Vessel and Helicopter Traffic

Support vessel traffic has the potential to disturb sea turtles, and there is also a risk of vessel strikes. Data show that vessel traffic is one cause of sea turtle mortality in the Gulf of Mexico(Lutcavage et al., 1997). While adult sea turtles are visible at the surface during the day and in clear weather, they can be difficult to spot from a moving vessel when resting below the water surface, during nighttime, or during periods of inclement weather. To reduce the potential for vessel strikes, the BOEM has issued NTL 2007-G04, which recommends protected species identification training and that vessel operators and crews maintain a vigilant watch for sea turtles and slow down or stop their vessel to avoid striking protected species, and requires operators to report sightings of any injured or dead protected species. When sea turtles are sighted, vessel operators and crews are required to attempt to maintain a distance of 150 ft (45 m) or greater whenever possible. Compliance with this NTL will minimize the likelihood of vessel strikes as well as reduce the chance for disturbing sea turtles (NMFS, 2007).

Helicopter traffic also has the potential to disturb sea turtles. However, while flying offshore, helicopters maintain altitudes above 700 ft (213 m) during transit to and from the working area. This altitude will minimize the potential for disturbing sea turtles, and no significant impacts are expected.

Impacts of a Small Fuel Spill

Potential spill impacts on sea turtles are discussed in recent EISs (MMS, 2007b, 2008b) and by the NMFS (2007) in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in theCentral and Western Planning Areas of the Gulf of Mexico. For this SEP, there are no unique sitespecific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Shell’s preventative measures during fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP is expected to mitigate and reduce the potential for impacts on sea turtles. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

Direct physical and physiological effects of exposure to diesel fuel could include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes; ingestion of oil directly or via contaminated prey; and stress from the activities and noise of response vessels and aircraft (MMC, 2010). However, due to the limited areal extent and short duration of water quality impacts from a small fuel spill, no significant impacts would be expected.

A small fuel spill in the lease area would be unlikely to affect sea turtle nesting beaches, as the lease area is 75 miles (120 km) from the nearest shoreline (Louisiana). As explained in

Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill

Impacts of oil spills on sea turtles can include direct impacts from oil exposure, as well as indirect impacts due to response activities and materials (e.g., vessel traffic, noise, and dispersants). Direct physical and physiological effects can include skin irritation, inflammation, or necrosis; chemical burns of skin, eyes, and mucous membranes; inhalation of toxic fumes and smoke (e.g.,from in situ burning of oil); ingestion of oil (and dispersants) directly or via contaminated food; and stress from the activities and noise of response vessels and aircraft. Complications of the above may lead to dysfunction of immune and reproductive systems, physiological stress, declining physical condition, and death. Behavioral responses can include displacement of animals from prime habitat, disruption of social structure, changing food availability and foraging distribution and/or patterns, changing reproductive behavior/productivity, and changing movement patterns or migration (MMC, 2010). In the unlikely event of a spill, implementation of Shell’s OSRP is expected to mitigate and reduce the po tential for these types of impacts on sea

turtles. SEP Sections 2j and 9b provide detail on spill response measures.

Studies of oil effects on loggerheads in a controlled setting (Lutcavage et al., 1995) suggest that sea turtles show no avoidance behavior when they encounter an oil slick, and any sea turtle in an affected area would be expected to be exposed. Sea turtles’ diving behaviors also put them at risk. Sea turtles rapidly inhale a large volume of air before diving and continually resurface over time, which may result in repeated exposure to volatile vapors and oiling (NMFS, 2007).

The OSRA results summarized in Table 18. 3 predict that some shorelines that support sea turtle nesting could be contacted within 30 days. The nearest nesting area of loggerhead turtles is found on beaches within the Breton NWR. This area (Plaquemines Parish) has a contact probability of 21% after 30 days.

Spilled oil reaching sea turtle nesting beaches could have effects on nesting sea turtles and egg development (NMFS, 2007). An oiled beach could affect nest site selection or result in no nesting at all (e.g., false crawls). Upon hatching and successfully reaching the water, hatchlings are subject to the same types of oil spill exposure hazards as adults. Hatchlings that contact oil residues while crossing a beach can exhibit a range of effects, from acute toxicity to impaired movement and normal bodily functions (NMFS, 2007).

Data from the Macondo spill provides additional information about potential impacts of a large oil spill on sea turtles to supplement the analysis presented in the lease sale EIS (MMS, 2007b). According to NMFS (2010b), approximately 600 dead turtles have been reported since the Macondo spill. Species include Kemp’s ridley turtles (481 individuals), loggerhead turtles (67 individuals), and green turtles (29 individuals). Oiled turtles include 18 dead individuals and

456 live, oiled animals that were either captured or stranded. Also, 278 turtle nests were translocated (271 loggerhead, 4 Kemp’ s ridley, and 3 green turtles) and more than 14,000 hatchlings were released. The strandings and captures ranged from the Louisiana/Texas border to Cape San Blas in the Florida Panhandle.

In the event of a large spill, the level of vessel and aircraft activity associated with spill response could disturb sea turtles and potentially result in vessel strikes, entanglement, or other injury or stress. Response vessels would operate in accordance with NTL 2007-G04 to reduce the potential for striking or disturbing these animals, and therefore no significant impacts are expected.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as de tailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on sea turtles are expected.

C.3.6 Piping Plover (Threatened)

The Piping Plover ( Charadrius melodus ) is a migratory shorebird that overwinters along the southeastern U.S. and Gulf of Mexico coasts. This threatened species is in decline as a result ofhunting, habitat loss and modification, predation, and disease (USFWS, 2003). Critical overwintering habitat has been designated, including beaches in Texas, Louisiana, Mississippi, Alabama, and Florida ( Figure 18. 3 ). Piping Plovers inhabit coastal sandy beaches and mudflats, feeding by probing for invertebrates at or just below the surface. They use beaches adjacent to foraging areas for roosting and preening (USFWS, 2010a). A species description is presented in a recent lease sale EIS (MMS, 2007b).

A large oil spill is the only IPF potentially affecting Piping Plovers. There are no IPFs associated with routine project activities that could affect these birds. A small fuel spill in the lease area would be unlikely to affect Piping Plovers because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2 ).

Impacts of a Large Oil Spill

The lease area is 77 miles (124 km) from the nearest shoreline inhabited by Piping Plovers. The

OSRA results summarized in Table 18. 3 predict that Louisiana and Mississippi shorelines designated as critical habitat for the wintering Piping Plover could be contacted by a spill within

30 days. Plaquemines Parish, which has a 21% probability of contact for the 30-day interval, includes Piping Plover critical habitat.

Plovers could become externally oiled while foraging on oiled shores or be exposed internally through ingestion of oiled intertidal sediments and prey (MMS, 2007b). Plovers congregate and feed along tidally exposed banks and shorelines, following the tide out and foraging at the water’s edge. It is possible that some deaths of Piping Plovers could occur, especially if spills occur during winter months when plovers are most common along the coastal Gulf or if spills contacted critical habitat. Impacts could also occur from vehicular traffic on beaches and other activities associated with spill cleanup. Shell has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j

. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on Piping Plovers are expected.

### Figure 18.3. Location of selected environmental features in relation to the lease area.

### C.3.7 Whooping Crane (Endangered)

The Whooping Crane ( Grus americana ) is an omnivorous wading bird and an endangered species. There are three wild populations in North America (Whooping Crane Eastern Partnership [WCEP], 2010). One population winters along the Texas coast at Aransas NWR and summers at Wood Buffalo National Park in Canada. This population represents the majority of the world’s population of free-ranging Whooping Cranes and reached a record population of 270 at Aransas NWR in December 2008 (WCEP, 2010). A non-migrating population has been re-introduced in central Florida, and another re-introduced population summers in Wisconsin and migrates to the southeastern U.S. for the winter. Whooping Cranes breed, migrate, winter, and forage in a variety of habitats, including coastal marshes and estuaries, inland marshes, lakes, ponds, wet meadows and rivers, and agricultural fields (USFWS, 2007). About 22,240 acres (9,000 ha) of salt flats on Aransas NWR and adjacent islands comprise the principal wintering grounds of the Whooping Crane. Aransas NWR is designated as critical habitat for the species ( Figure 18. 3 ). A species description is presented in a recent lease sale EIS (MMS, 2007b).

A large oil spill is the only IPF potentially affecting Whooping Cranes. A small fuel spill in the lease area would be unlikely to affect Whooping Cranes due to the distance from Aransas NWR. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill

A large oil spill has a low probability of affecting Whooping Cranes because the lease area is approximately 518 miles (833 km) from its critical habitat (Aransas NWR, Texas) and the OSRA modeling predicts that a spill in the lease area will not contact the shorelines of the Aransas NWR within 30 days.

In the event of oil exposure, Whooping Cranes could become externally oiled while foraging in oiled areas or internally exposed to oil through ingestion of contaminated shellfish, frogs, and fishes. It is possible that some death of Whooping Cranes could occur. Shell has extensive resources available to protect and rehabilitate wildlife in the event of a spill reaching the shoreline, as detailed in the OSRP.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on Whooping Cranes are expected.

C.3.8 Gulf Sturgeon (Threatened)

The Gulf sturgeon (

Acipenser oxyrinchus desotoi ) is a threatened fish species that inhabits major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida (Barkuloo, 1988; Wakeford, 2001). An anadromous fish that migrates from the sea upstream into coastal rivers to spawn in freshwater, it historically ranged from the Mississippi River to Charlotte Harbor, Florida (Wakeford, 2001). Today, this range has contracted to encompass major rivers and inner shelf waters from the Mississippi River to the Suwannee River, Florida. Populations have been depleted or even extirpated throughout this range by fishing, shoreline development, dam construction, water quality changes, and other factors (Barkuloo, 1988; Wakeford, 2001). These declines prompted the listing of the Gulf sturgeon as a threatened species in 1991. The best known populations occur in the Apalachicola and Suwannee Rivers in Florida (Carr, 1996; Sulak and Clugston, 1998), the Choctawhatchee River in Alabama (Fox et al., 2000), and the Pearl River in Mississippi/Louisiana (Morrow et al., 1998). Critical habitat in the Gulf extends from LakeBorgne, Louisiana (St. Bernard Parish) to Suwannee Sound, Florida (Levy County) (NMFS, 2010c) ( Figure 18. 3 ). A species description is presented in a recent lease sale EIS (MMS, 2007b) and in the recovery plan for this species (USFWS and Gulf States Marine Fisheries Commission, 1995).

A large oil spill is the only IPF potentially affecting Gulf sturgeon. There are no IPFs associated with routine project activities that could affect this species. A small fuel spill in the lease area would be unlikely to affect Gulf sturgeon because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in Section A.9.2 ).

Impacts of a Large Oil Spill

Potential spill impacts on Gulf sturgeon are discussed in recent EISs (MMS, 2007b, 2008b) and by the NMFS (2007) in its Biological Opinion for the Five-Year Oil and Gas Leasing Program in theCentral and Western Planning Areas of the Gulf of Mexico. For this SEP, there are no unique sitespecific issues with respect to this species.

The lease area is about 112 miles (181 km) from the nearest Gulf sturgeon critical habitat. The OSRA modeling ( Table 18.3 ) predicts 1% probability that a spill in the lease area will contact the coastal areas inhabited by Gulf sturgeon within 30 days.

In the event of oil reaching Gulf sturgeon habitat, the fish could be affected by direct ingestion, ingestion of oiled prey, or the absorption of dissolved petroleum products through the gills. Based on the life history of this species, subadult and adult Gulf sturgeon would be most vulnerable to a marine oil spill, and would be vulnerable only during winter months (from 1 September through 30 April) when this species is foraging in estuarine and marine habitats (NMFS, 2007).

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. Shell has extensive resources available to protect coastal and estuarine wildlife and habitats in the event of a spill reaching the shoreline, as detailed in the OSRP. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on Gulf sturgeon are expected.

C.3.9 Beach Mice (Endangered)

Four subspecies of endangered beach mouse ( Peromyscus polionotus ) occur on the barrier islands of Alabama and the Florida Panhandle. They are the Alabama, Choctawatchee, Perdido Key, and St. Andrew beach mouse. Critical habitat has been designated for all four subspecies; Figure 18.3 shows the critical habitat combined for all four subspecies. Species descriptions are provided in a recent lease sale EIS (MMS, 2007b).

A large oil spill is the only IPF potentially affecting subspecies of beach mouse. There are no IPFs associated with routine project activities that could affect these animals due to the distance from shore and the lack of any onshore support activities near their habitat. A small fuel spill i n the lease area would not affect any subspecies of beach mouse because a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see explanation in

Section A.9.2 ).

Impacts of a Large Oil Spill

Potential spill impacts on beach mice are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to these species.The lease area is about 111 miles (179 km) from the nearest beach mouse critical habitat. The

OS RA modeling predicts that a spill in the lease area has 1% probability of contact with beach mouse critical habitat within 30 days.

In the event of oil contacting these beaches, beach mice could experience several types of direct and indirect impacts. Contact with spilled oil could cause skin and eye irritation and subsequent infection; matting of fur; irritation of sweat glands, ear tissues, and throat tissues; disruption of sight and hearing; asphyxiation from inhalation of fumes; and toxicity from ingestion of oil and contaminated food. Indirect impacts could include reduction of food supply, destruction of habitat, and fouling of nests. Impacts could also occur from vehicular traffic and other activities associated with spill cleanup.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’ s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on beach mice are expected.

C.4 Coastal and Marine Birds

C.4.1 Marine and Pelagic Birds

A variety of seabirds may occur in the pelagic environment of the project areas (Clapp et al., 1982a,b, 1983; Peake, 1996; Hess and Ribic, 2000). Seabirds spend much of their lives offshore over the open ocean, except during breeding season when they nest along the coast. In addition, other birds such as waterfowl, marsh birds, and shorebirds may occasionally be present over open ocean areas. No endangered or threatened bird species are likely to occur at the project area due to the distance from shore. For a discussion of shorebirds and coastal nesting birds, see Section C.4.2

.

Seabirds of the northern Gulf of Mexico were surveyed from ships during the GulfCet II program. Hess and Ribic (2000) reported that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater area. From these surveys, four ecological categories of seabirds were documented in the deepwater areas of the Gulf: summer migrants (shearwaters, storm petrels, boobies); summer residents that breed in the Gulf (Sooty Tern, Least Tern, Sandwich Tern, Magnificent Frigatebird); winter residents (gannets, gulls, jaegers); and permanent resident species (Laughing Gull, Royal Tern, Bridled Tern) (Hess and Ribic, 2000).

Common seabird species include Wilson’s Storm -Petrel ( Oceanites oceanicus ), Magnificent Frigatebird ( Fregata magnificens ), Northern Gannet ( Morus bassanus ), Masked Booby ( Sula dactylatra

), Brown Booby ( Sula leucogaster ), Cory’s Shearwater ( Calonectris diomedea ), Greater Shearwater ( Puffinus gravis ), and Audubon Shearwater ( Puffinus lherminieri ). Seabirds are distributed Gulf-wide and are not specifically associated with the lease area.

Relationships with hydrographic features were found for several seabird species, possibly due to effects of hydrography on nutrient levels and productivity of surface waters where birds forage. GulfCet II did not estimate bird densities; however, Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2

.

Trans-Gulf migrant birds including shorebirds, wading birds, and terrestrial birds may also be present in the lease area. Migrant birds may use offshore structures and platforms for resting, feeding, or as temporary shelter from inclement weather (Russell, 2005). Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate

around these structures.IPFs potentially affecting marine and pelagic birds include drilling rig presence, noise, and lights; support vessel and helicopter traffic; and two types of accidents (a small fuel spill and a large oil spill). Effluent discharges are likely to have negligible impacts on the birds due to rapid dispersion, the small area of ocean affected, the intermittent nature of the discharges, and the mobility of these animals. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on birds.

Impacts of Drilling Rig Presence, Noise, and Lights

Birds that frequent platforms may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion of effluents and air pollutants. Birds migrating over water have been known to strike offshore structures, resulting in death or injury (Wiese et al., 2001; Russell, 2005). Mortality of migrant birds at tall towers and other land-based structures has been reviewed extensively, and the mechanisms involved in platform collisions appear to be similar. In some cases, migrants simply do not see a part of the platform until it is too late. In other cases, navigation may be disrupted by noise (Russell, 2005). On the other hand, offshore structures are suitable stopover habitats for most trans-Gulf migrant species, and most of the migrants that stop over on platforms probably benefit from their stay, particularly in spring (Russell, 2005). Due to the limited scope, timing, and geographic extent of drilling activities in this SEP, any impacts on populations of either seabirds or trans-Gulf migrant birds are not expected to be significant.

A study in the North Sea indicated that platform lighting causes circling behavior in various birds, especially on cloudy nights; a pparently the birds’ geomagnetic compass is upset by the red part of the spectrum from the lights currently in use (Poot et al., 2008). The numbers varied greatly, from none at all to some tens of thousands of birds per night per platform, with an apparent effect radius of up to 3 miles (5 km). A study in the Gulf of Mexico also noted the phenomenon, but did not recommend mitigation (Russell, 2005). Factors to consider in evaluating this impact in the Gulf of Mexico would include the lower incidence of cloudy and foggy days in the Gulf of Mexico versus the North Sea. Due to the limited scope and short duration of drilling activities proposed in this SEP, lighting impacts, collisions, or other adverse effects are unlikely, and no significant impacts are expected.

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters are unlikely to significantly disturb pelagic birds in open, offshore waters. It is likely that individual birds would experience, at most, only short-term behavioral disruption, and the impact would not be significant.

Impacts of a Small Fuel Spill

Potential spill impacts on marine birds are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to spill impacts on these animals.

The probability of a fuel spill will be minimized by Shell’s preventative measu res during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts on marine and pelagic birds. SEP Sections 2j

and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

Birds exposed to oil on the sea surface could experience direct physical and physiological effects including skin irritation; chemical burns of skin, eyes, and mucous membranes; and inhalation of toxic fumes. Due to the limited areal extent and short duration of water quality impacts from a small fuel spill, secondary impacts due to ingestion of oil via contaminated prey or reductions in prey abundance are unlikely. Due to the low densities of birds in open ocean areas, the small area affected, and the brief duration of the surface slick, no significant impacts on pelagic birds would be expected.

Impacts of a Large Oil Spill

Potential spill impacts on marine and pelagic birds are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to spill impacts on

these animals.

Pelagic seabirds could be exposed to oil from a spill at the project area. Hess and Ribic (2000) reported that terns, storm-petrels, shearwaters, and jaegers were the most frequently sighted seabirds in the deepwater Gulf of Mexico (>200 m). Powers (1987) indicates that seabird densities over the open ocean typically are <10 birds/km 2 . The number of pelagic birds that could be affected in open, offshore waters would depend on the extent and persistence of the oil

slick.

The Macondo spill provides relevant information about the species of pelagic birds that may be affected in the event of a large oil spill. Birds that have been treated for oiling include several pelagic species such as the Northern Gannet, Magnificent Frigatebird, and Masked Booby (USFWS, 2011). The Northern Gannet is among the species with the largest numbers of birds affected by the spill.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on marine and pelagic birds are expected.

C.4.2 Shorebirds and Coastal Nesting Birds

Threatened and endangered bird species (Piping Plover and Whooping Crane) have been discussed previously in Section C.3 . Various species of non-endangered birds are also found along the northern Gulf Coast, including diving birds, shorebirds, marsh birds, wading birds, and waterfowl. Gulf Coast marshes and beaches also provide important feeding grounds and nesting habitats. Species that breed on beaches, flats, dunes, bars, barrier islands, and similar habitats include the Sandwich Tern, Wilson’s Plover, Black Skimmer, Forster’s Tern, Gull -Billed Tern, Laughing Gull, Least Tern, and Royal Tern (USFWS, 2010b). Additional information is presented in recent lease sale EISs (MMS, 2007b, 2008).

The Brown Pelican ( Pelecanus occidentalis ) was delisted from Federal endangered status in 2009 (USFWS, 2010c). However, this species is listed as a species of greatest conservation need by the State of Mississippi (Mississippi Department of Wildlife, Fisheries and Parks, 2011) and as a species of special concern by the State of Florida (Florida Fish and Wildlife Conservation Commission, 2011). Brown Pelicans inhabit coastal habitats and forage within both coastal waters and waters of the inner continental shelf. Aerial and shipboard surveys, including GulfCet and GulfCet II, indicate that Brown Pelicans do not occur over deep offshore waters (Fritts and Reynolds, 1981; Peake, 1996; Hess and Ribic, 2000). Nearly half the southeastern population ofBrown Pelicans lives in the northern Gulf Coast, generally nesting on protected islands (USFWS, 2010b).

IPFs potentially affecting shorebirds and coastal nesting birds include support vessel and helicopter traffic and a large oil spill. A small fuel spill in the lease area would be unlikely to affect shorebirds or coastal nesting birds, as the lease area is 75 miles (120 km) from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up. Compliance with NTL 2007-G03 will minimize the potential for marine debris-related impacts on shorebirds.

Impacts of Support Vessel and Helicopter Traffic

Support vessels and helicopters will transit coastal areas near Port Fourchon and Boothville, Louisiana, where shorebirds and coastal nesting birds may be found. These activities could periodically disturb individuals or groups of birds within sensitive coastal habitats (e.g., wetlands that may support feeding, resting, or breeding birds).

Vessel traffic may disturb some foraging and resting birds. Flushing distances vary among species and individuals (Rodgers and Schwikert, 2002). The disturbances will be limited to flushing birds away from vessel pathways; known distances are from 65 to 160 ft (20 to 49 m) for personal watercraft and 75 to 190 ft (23 to 58 m) for outboard-powered boats (Rodgers and

Schw ikert, 2002). Flushing distances may be similar or less for the support vessels to be used for Shell’s project, and some species such as gulls are attracted to boats. Support vessels will not approach nesting or breeding areas on the shoreline, so nesting birds, eggs, and chicks will not be disturbed. Vessel operators will use designated navigation channels and comply with posted speed and wake restrictions while transiting sensitive inland waterways. Due to the limited scope, timing, and geographic extent of drilling activities, any short-term impacts are not expected to be biologically significant to coastal bird populations.

Aircraft traffic can cause some disturbance to birds onshore and offshore. Responses are highly dependent on the type of aircraft, the bird species, the activities that animals were previously engaged in, and previous exposures to overflights (Efroymson et al., 2000). Helicopters seem to cause the most intense responses over other human disturbances for some species (Bélanger and Bédard, 1989). However, Federal Aviation Administration Advisory Circular No. 91 -36D recommends that pilots maintain a minimum altitude of 2,000 ft (610 m) when flying over noise-sensitive areas such as wildlife refuges, parks, and areas with wilderness characteristics. This is greater than the distance (slant range) at which aircraft overflights have been reported to cause behavioral effects on most species of birds studied (Efroymson et al., 2000). With these guidelines in effect, it is likely that individual birds would experience, at most, only short-term behavioral disruption.

Impacts of Large Oil Spill

The OSRA results summarized in Table 18. 3 predict that shorelines of Louisiana, Mississippi, Alabama, and Florida that include habitat for shorebirds and coastal nesting birds could be affected within 30 days.

Data from the Macondo spill provides additional information about the species of coastal birds that may be affected in the event that a large oil spill reached coastal habitats; this information supplements the analysis presented in the lease sale EIS (MMS, 2007b). According to USFWS (2010d) and based on the latest reports, about 5,000 dead birds had been collected since the spill began, and about 1,900 of the dead animals were visibly oiled. In addition, more than 2,000 oiled birds have been collected alive and about 1,200 released (NMFS, 2010b). According to the USFWS (2011), bird species that were visibly oiled following the Macondo spill include the following:Brown Pelican Masked Booby

Ma gnificent Frigatebird Laughing Gull Herring Gull

Northern Gannet Black Crowned Night Heron

Tri-colored Heron

Green Heron Cattle Egret Snowy Egret Reddish Egret

Common Tern Royal Tern Caspian Tern

Sandwich Tern
Forster’s Tern

Least Tern
Black Skimmer

White Ibis Roseate Spoonbill

Willet Sanderling Semipalmated Sandpiper Clapper Rail

According to the USFWS (2011), species with the largest numbers of dead, oiled birds were Laughing Gull, Northern Gannet, Brown Pelican, Royal Tern, Black Skimmer, Least Tern,

un identified Gull, and unidentified Tern. Coastal birds can be exposed to oil as they float on the water’s surface, dive during foraging, or wade in oiled coastal waters. Oiled birds can lose the ability to fly, dive for food, or float on the water, which could lead to drowning (USFWS, 2010e). Oil interferes with the water repellency of feathers and can cause hypothermia under certain conditions. As birds groom themselves, they can ingest and inhale the oil on their bodies. Scavengers such as Bald Eagles and gulls can be exposed to oil by feeding on carcasses of contaminated fish and wildlife. While ingestion can kill animals immediately, more often it results in lung, liver, and kidney damage, which can lead to death. Bird eggs may be damaged if an

oil ed adult sits on the nest or if oil covers the eggs.

As noted above, the Brown Pelican was recently removed from the endangered species list. More than 300 dead Brown Pelicans were collected in the Gulf following the Macondo spill, (USFWS, 2010d). These data indicate that the Brown Pelican may be particularly at risk of oiling in the event of a large spill reaching coastal waters. Threats to the Brown Pelican include direct contact with oil, disturbance by cleanup activities, and long-term habitat contamination.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on shorebirds and coastal nesting birds are expected.C.5 Fisheries Resources

C.5.1 Pelagic Communities and Ichthyoplankton

Biggs and Ressler (2000) reviewed the biology of pelagic communities in the deepwater environment of the northern Gulf of Mexico. The biological oceanography of the region is dominated by the influence of the Loop Current, whose surface waters are among the most oligotrophic in the world’s oceans. Superimposed on this low -productivity condition are productive “hot spots” associated with entrainment of nutrient -rich Mississippi River water and mesoscale oceanographic features. Anticyclonic and cyclonic hydrographic features play an important role in determining biogeographic patterns and controlling primary productivity in the northern Gulf of Mexico (Biggs and Ressler, 2000).

Most fishes inhabiting shelf or oceanic waters of the Gulf of Mexico have planktonic eggs and larvae (Ditty, 1986; Ditty et al., 1988; Richards et al., 1989, 1993). Pelagic eggs and larvae become part of the planktonic community for various lengths of time (10 to 100 days, depending on the species) (MMS, 2007b).

IPFs potentially affecting pelagic communities and ichthyoplankton include drilling rig presence, noise, and lights; effluent discharges; water intakes; and two types of accidents (a small fuel spill and a large oil spill).

Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as a fish-attracting device (FAD). In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994). This FAD effect could possibly enhance the feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, impacts on fish populations, whether beneficial or adverse, are considered minor.

Impacts of Effluent Discharges

Treated sanitary and domestic wastes may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. These wastes may have elevated levels of nutrients, organic matter, and chlorine, but will be diluted rapidly to undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Deck drainage may have a slight effect on the pelagic environment in the immediate vicinity of these discharges. Deck drainage from contaminated areas will be passed through an oil and water separator prior to release, and discharges will be monitored for visible sheen. The discharges may have slightly elevated levels of hydrocarbons but will be diluted rapidly to undetectable levels within tens to hundreds of meters from the source. Minimal impacts on water quality, plankton, and nekton are anticipated.

Other discharges in accordance with the NPDES permit, such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water, are expected to be diluted rapidly and have little or no impact on water column biota.

Impacts of Water Intakes

Seawater will be drawn from several meters below the ocean surface for various services including firewater and once-through non-contact cooling of machinery on the drilling rig ( SEP Table 7a ). Section 316(b) of the Clean Water Act requires NPDES permits to ensure thatthe location, design, construction, and capacity of cooling water intake structures reflect the best technology available to minimize adverse environmental impact from impingement and entrainment of aquatic organisms. Construction of the rig planned for use in this SEP, the Transocean Deepwater Nautilus , started prior to 17 July 2006, and therefore is not subject to the cooling water intake permit requirements of NPDES Permit GMG290000. If a different rig is selected, it will comply with applicable NPDES requirements. The design and operational features of the rig combined with the geographical area of operation suggest impingement and entrainment impacts will be below a level of concern.

Impacts of a Small Fuel Spill

Potential spill impacts on fisheries resources are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to spill impacts.

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts on pelagic communities, including ichthyoplankton. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brie f.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

A small fuel spill could have localized impacts on phytoplankton, zooplankton, ichthyoplankton, and nekton. Due to the limited areal extent and short duration of water quality impacts, a small fuel spill would be unlikely to produce detectable impacts on pelagic communities.

Impacts of a Large Oil Spill

A large oil spill could affect water column biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. A large spill that persisted for weeks or months would be more likely to affect these communities. While adult and juvenile fishes may actively avoid a large spill, planktonic eggs and larvae would be unable to avoid contact. Eggs and larvae of fishes in the upper layers of the water column are especially vulnerable to oiling; certain toxic fractions of spilled oil may be lethal to these life stages. Impacts would be potentially greater if local scale currents retained planktonic larval assemblages (and the floating oil slick) within the same water

mass.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevent ion measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on pelagic communities and ichthyoplankton are expected.

C.5.2 Essential Fish Habitat

Essential Fish Habitat (EFH) is defined as those waters and substrate necessary to fish for spawning, breeding, feeding, and growth to maturity. Under the Magnuson-Stevens Fishery Conservation and Management Act, as amended, Federal agencies are required to consult onactivities that may adversely affect EFH designated in Fishery Management Plans developed by the regional Fishery Management Councils.

The Gulf of Mexico Fishery Management Council (GMFMC) has prepared Fishery Management Plans for corals and coral reefs, shrimps, stone crab, spiny lobster, reef fishes, coastal migratory pelagic fishes, and red drum. In 2005, the EFH for these managed species was redefined in Generic Amendment No. 3 to the various Fishery Management Plans (GMFMC, 2005). The EFH for most of these GMFMC-managed species is on the continental shelf in waters shallower than 600 ft (183 m). The shelf edge is the outer boundary for coastal migratory pelagic fishes, reef fishes, and shrimps. EFH for corals and coral reefs includes some shelf-edge topographic features on the Texas-Louisiana OCS, the nearest of which is in the West Delta Area, South Addition, located 94 miles (151 km) west of the lease area.

Highly migratory pelagic fishes, which occur as transients in the lease area, are the only remaining group for which EFH has been identified in the deepwater Gulf of Mexico. Species in this group, including tunas, swordfishes, billfishes, and sharks, are managed by NMFS. Highly migratory species with EFH at or near the lease area include the following (NMFS, 2009):

Atlantic bluefin tuna (spawning, eggs, larvae) Atlantic skipjack tuna (spawning, adults) Atlantic yellowfin tuna (spawning, juveniles, adults) Albacore tuna (adults) Atlantic swordfish (larvae, juveniles) Blue marlin (juveniles, adults) White marlin (juveniles, adults) Longbill spearfish (juveniles, adults) Oceanic whitetip shark (all) Silky shark (all) Longfin mako shark (all) Bigeye tresher shark (all) Whale shark (all)

Research indicates the central and western Gulf of Mexico may be important spawning habitat for Atlantic bluefin tuna, and NMFS (2009) has designated a Habitat Area of Particular Concern (HAPC) for this species. The HAPC covers much of the deepwater Gulf of Mexico, including the lease area ( Figure 3 ). The areal extent of the HAPC is approximately 300,000 km 2 (15,000 mi 2 ). The prevailing assumption is that Atlantic bluefin tuna follow an annual cycle of foraging in June through March off the eastern U.S. and Canadian coasts, followed by migration to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

Other HAPCs have been identified in the Gulf of Mexico by the GMFMC (2005). These include the Florida Middle Grounds, Madison-Swanson Marine Reserve, Tortugas North and South Ecological Reserves, Pulley Ridge, and several individual reefs and banks of the northwestern Gulf of Mexico ( Figure 3 ). The nearest of these is Jakkula Bank, located 224 miles (360 km) southwest of the

lease area.

Routine IPFs potentially affecting EFH and fisheries resources include drilling rig presence, noise, and lights; effluent discharges; and water intakes. In addition, two types of accidents

– a small fuel spill and a large oil spill

– may impact EFH and fisheries resources.Impacts of Drilling Rig Presence, Noise, and Lights

The drilling rig, as a floating structure in the deepwater environment, will act as an FAD. In oceanic waters, the FAD effect would be most pronounced for epipelagic fishes such as tunas, dolphin, billfishes, and jacks, which are commonly attracted to fixed and drifting surface structures (Holland et al., 1990; Higashi, 1994; Relini et al., 1994). This FAD effect would possibly enhance feeding of epipelagic predators by attracting and concentrating smaller fish species. Because the drilling rig is a single, temporary structure, any impacts on EFH for highly migratory pelagic fishes are considered minor.

Impacts of Effluent Discharges

Other effluent discharges affecting EFH by diminishing ambient water quality include drilling mud and cuttings, treated sanitary and domestic wastes, deck drainage, and miscellaneous discharges such as desalination unit brine and uncontaminated cooling water, fire water, and ballast water. Impacts on water quality have been discussed previously. No significant impacts on EFH for highly migratory pelagic fishes are expected from these discharges.

Impacts of Water Intakes

As noted previously, cooling water intake will cause entrainment and impingement of plankton, including fish eggs and larvae (ichthyoplankton). Due to the limited scope, timing, and geographic extent of drilling activities, any short-term impacts on EFH for highly migratory pelagic fishes are not expected to be biologically significant.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSR P will mitigate and reduce the potential for impacts on EFH. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to spill impacts.

A small fuel spill in offshore waters would produce a slick on the water surface and increase the concentrations of petroleum hydrocarbons and their degradation products. The extent and persistence of impacts would depend on the meteorological and oceanographic conditions at the time and the effectiveness of spill response measures. Section A.9.2 discusses the likely fate of a small fuel spill and indicates that over 90% would be evaporated or dispersed naturally within

24 hours. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions.

A small fuel spill could have localized impacts on EFH for highly migratory pelagic fishes, including tunas, swordfishes, billfishes, and sharks. These species occur as transients in the lease area. A spill would also produce short-term impact on water quality in the HAPC for spawning Atlantic bluefin tuna, which covers much of the deepwater Gulf of Mexico. The affected area would represent a negligible portion of the HAPC, which covers 297,312 km 2
(114,793 mi 2 ) of the Gulf of Mexico.

A small fuel spill would not affect EFH for corals and coral reefs; the nearest coral EFH is in the West Delta Area, South Addition, located 94 miles (151 km) west of the lease area. A small fuel spill would float and dissipate on the sea surface and would not contact these features.Impacts of a Large Oil Spill

Potential spill impacts on EFH are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP

, there are no unique site-specific issues with respect to EFH.

An oil spill in offshore waters would temporarily increase hydrocarbon concentrations on the water surface and potentially the subsurface as well. Given the extent of EFH designations in the Gulf of Mexico (GMFMC, 2005; NMFS, 2009), some impact on EFH would be unavoidable.

A large spill could affect the EFH for many managed species including shrimps, stone crab, spiny lobster, corals and coral reefs, reef fishes, coastal migratory pelagic fishes, and red drum. It would result in adverse impacts on water quality and water column biota including phytoplankton, zooplankton, ichthyoplankton, and nekton. In coastal waters, sediments could be contaminated and result in persistent degradation of the seafloor habitat for managed demersal fish and shellfish species.

The lease area is within the HAPC for spawning Atlantic bluefin tuna (NMFS, 2009). A large spill could temporarily degrade the HAPC due to increased hydrocarbon concentrations in the water column, with the potential for lethal or sublethal impacts on spawning tuna and their offspring. Potential impacts would depend in part on the timing of a spill, as this species migrates to the Gulf of Mexico to spawn in April, May, and June (NMFS, 2009).

The pinnacle trend area, located 43 miles (69 km) north-northwest of the lease area, is designated as EFH under the corals and coral reefs management plan. An accidental spill would be unlikely to affect this area. A surface slick would not reach these features. Although there are reports of subsurface plumes resulting from the use of subsea dispersants during the Macondo spill, the distance and difference in water depth are factors that would make an impact unlikely. Near-bottom currents in the region are expected to flow along the isobaths (Nowlin et al., 2001) and typically would not carry a plume up onto the continental shelf edge.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in

S EP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on EFH are expected.

C.6 Archaeological Resources

C.6.1 Shipwreck Sites

MC 393 is not on the list of leases with high potential for historic shipwrecks. Two sonar contacts were identified along the impact zones for the proposed anchor array. One of these was interpreted as probable modern debris. The second contact could not be reliably identified and so will be avoided during anchor placement. None of the other sonar contacts outside of the potential impact zone have been interpreted as archaeologically significant (Fugro Geoservices, Inc., 2007, 2009a, 2011 ).

No historic shipwreck sites occur in the lease area (see SEP Section 6 ). A small fuel spill would not affect shipwrecks in adjoining blocks because the oil would float and dissipate on the sea surface. The impact of a large oil spill that could contact shipwrecks in other areas is considered

below a level of concern.Impacts of a Large Oil Spill

The MMS (2007b) estimated that a severe subsurface blowout could resuspend and disperse sediments within a 984-ft (300-m) radius. Because there are no historic shipwrecks in the lease area, a large oil spill would not result in any impact on archaeological resources.

A spill entering shallow coastal waters could conceivably contaminate an undiscovered shipwreck site. The OSRA modeling summarized in Table 3 predicts that Louisiana, Mississippi, Alabama, and Florida shorelines could be contacted by a spill within 30 days. Also, as noted by MMS (2007b), should an oil spill contact a coastal historic site, such as a fort or a lighthouse, the major impact would be a temporary, reversible visual impact from oil contact and contamination of the

site and its environment.

Previous analyses (MMS, 2007a, 2008b) concluded that oil spills would be unlikely to affect archaeological sites beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsite and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (Joint Analysis Group, 2010c). While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could have the potential to contact shipwreck sites beyond the 984-ft (300-m) radius estimated by MMS (2007a, 2008b), depending on its extent, trajectory, and persistence. If oil from a subsea spill should come into contact with wooden shipwrecks on the seafloor it could adversely affect their condition or preservation.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on historic shipwrecks are expected.

C.6.2 Prehistoric Archaeological Sites

With water depths ranging from 7,301 to 7,385 ft (2,225 to 2,251 m), the wellsites are well beyond the 197-ft (60-m) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Because prehistoric archaeological sites are not found in the lease area, the only relevant IPF is a large oil spill that would reach coastal waters within the 197-ft (60-m) depth contour.

Impacts of a Large Oil Spill

Because prehistoric archaeological sites are not found in the lease area, they would not be affected by the physical effects of a subsea blowout. The MMS (2007b) estimates that a severe subsurface blowout could resuspend and disperse sediments within a 984-ft (300-m) radius.

Along the northern Gulf Coast, prehistoric sites occur frequently along the barrier islands and mainland coast and along the margins of bays and bayous (MMS, 2007b). The OSRA modeling

summarized in Table 18.3 predicts that Texas and Louisiana, Mississippi, Alabama, and Florida shorelines could be contacted by a spill within 30 days. A spill reaching a prehistoric site along these shorelines could coat fragile artifacts or site features and compromise the potential for radiocarbon dating organic materials in a site (although other dating methods are available and it is possible to decontaminate an oiled sample for radiocarbon dating). Coastal prehistoric sites could also be damaged by spill cleanup operations (e.g., by destroying fragile artifacts and disturbing the provenance of artifacts and site features).A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on archaeological resources are expected.

C.7 Coastal Habitats and Protected Areas

Coastal habitats in the northern Gulf of Mexico that may be affected by oil and gas activities are described in recent EISs (MMS, 2007b, 2008b) and in a literature review by Collard and Way (1997). Sensitive coastal habitats are also tabulated in the OSRP. Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. Generally, most of the northeastern Gulf is fringed by barrier beaches, with wetlands and/or submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries.

Due to the distance from shore, there are no IPFs associated with routine activities that are likely to affect beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area. The support bases at Port Fourchon and Boothville are not located in wildlife refuges or wilderness areas. Potential impacts of support vessel traffic are briefly addressed below.

A small fuel spill in the lease area would be unlikely to affect coastal habitats because the lease area is 75 miles (120 km) from the nearest shoreline. As explained in Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of Support Vessel Traffic

For OCS activities in general, support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Support operations, including crew boats and supply boats as detailed in SEP Section 14 , may have a minor incremental impact on coastal habitats or protected areas. Impacts will be minimized by following the speed and wake restrictions in harbors and channels.

Impacts of a Large Oil Spill

Potential spill impacts on coastal habitats are discussed in recent EISs (MMS, 2007b, 2008b). Coastal habitats inshore of the project area include barrier beaches and dunes, wetlands, and submerged seagrass beds. For this SEP, there are no unique site- sp ecific issues with respect to

coastal habitats.

The OSRA results summarized in Table 18. 3 predict that shorelines of Louisiana, Mississippi, Alabama, and Florida could be affected within 30 days. Plaquemines Parish, Louisiana has the highest probability of contact for the 30-day intervals (21%). After 30 days, 14 counties or parishes may be contacted from Cameron, Louisiana, to Bay, Florida.

The shorelines within the geographic range predicted by the OSRA modeling include extensive barrier beaches and wetlands, with submerged seagrass beds occurring in sheltered areas behind the barrier islands and in estuaries. NWRs and other protected areas along the coast are discussed in the lease sale EIS (MMS, 2007b) and Shell’s OSRP. Coastal wildlife refuges, wilderness areas, and State and national parks within the geographic range of the potential shoreline contacts after 30 days include the following:

Sabine NWR

Cameron Prairie NWRHancock County Marsh Coastal Reserve

Bon Secour NWR Grand Bay NWR Choctawatchee Bay Service Water and Impoundment Monitoring Area Point Washington Outstanding Florida Water Perdido Key State Recreation Area

Cameron Prairie NWR

LaCassine NWR

Little Pecan Island Preserve Peveto Woods Sanctuary

Lower Neches WMA

Rockefeller WMA Paul J. Rainey WMA Atchafalaya Delta WMA Mandalay NWR Isles Dernieres Barrier Islands Refuge

Pointe Au Chien WMA

Wisner WMA

Salvador WMA

Jean Lafitte National Historical Park and Preserve

Delta NWR

Pass a Loutre WMA

Breton NWR

St. Bernard State Park

Biloxi WMA Bayou Sauvage NWR

Gulf Islands National Seashore

Buccaneer State Park Davis Bayou Coastal Preserve The Grand Bay Savanna Tract

Meaher State Park Big Lagoon State Recreation Area Pensacola Bay Service Water and Impoundment Monitoring Area

Henderson State Park

St . Andrew Bay Watershed Service Water and Impoundment Monitoring Area

Jourdan River Coastal Reserve Mississippi Sandhill Crane NWR

Penalver State Park Weeks Bay National Estuarine Research Reserve Fort Pickens State Park Aquatic Preserve St. Andrews State Park Aquatic Preserve

Biloxi River Coastal Reserve Pascagoula River Coastal Reserve

Gulf State Park

Deer Lake State Park Grand Bay National Estuarine Research Reserve

W.L. Holland WMA Grayton Beach State Park Outstanding Florida Water Tarkiln Bayou State Preserve Yellow River Wildife Management AreaBig Branch Marsh NWR

Pearl River WMA

Deer Island State Coastal Preserve

Wolf River Coastal Reserve Old Fort Bayou Coastal Reserve Grand Bayou Coastal Preserve

Bellefontaine Point Coastal Reserve Graveline Bay Coastal Reserve Bayou Portage Coastal Reserve

Biloxi Marshes State Coastal Preserve

The OSRA results in Table 18. 3 include only shoreline segments with contact probabilities greater than 0.5% within 30 days; other coastal areas could be affected at lower contact probabilities within 30 days, or from a spill persisting for more than 30 days. Additional NWRs and managed wildlife areas occur along the Gulf Coast. These areas include habitats such as barrier beach and dune systems, wetlands, and submerged seagrass beds that support diverse wildlife, including endangered or threatened species.

The level of impacts from oil spills on coastal habitats depends on many factors, including the oil characteristics, the geographic location of the landfall, and the weather and oceanographic conditions at the time (MMS, 2007b). Oil that makes it to beaches may be either liquid weathered oil, an oil-and-water mousse, or tarballs (MMS, 2007b). Oil is generally deposited on beaches in lines defined by wave action at the time of landfall. Oil that remains on the beach will thicken as its volatile components are lost. Thickened oil may form tarballs or aggregations that incorporate sand, shell, and other materials into its mass. Tar may be buried to varying depths under the sand. On warm days, both exposed and buried tarballs may liquefy and ooze. Oozing may also serve to expand the size of a mass as it incorporates beach materials. Oil on beaches may be cleaned up manually, mechanically, or both. Some oil can remain on the beach at varying depths and may persist for several years as it slowly biodegrades and volatilizes. Wetlands are highly sensitive to oiling. The MMS (2007b) predicted that for every 50 bbl of oil contacting wetlands, approximately 6.7 acres (2.7 ha) of wetland vegetation will experience dieback. Thirty percent of these damaged wetlands are assumed to recover within 4 years, and 85% within 10 years. About 15% of the contacted wetlands are expected to be converted permanently to open-water habitat. The critical concentration of oil is that concentration above which impacts to wetlands will be long-term and recovery will take longer than two growing seasons, and which causes plant mortality and some permanent wetland loss. Critical concentrations of various oils are expected to vary broadly for wetland types and wetland plant species. Louisiana wetlands are assumed to be more sensitive to oil contact than elsewhere in the Gulf because of high cumulative stress (MMS, 2007b). In addition to the direct impacts of oil, cleanup activities in marshes may accelerate rates of erosion and retard recovery rates, which have been reported to require from years to decades following a spill (MMS, 2007b).

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SE P Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on coastal habitats are expected.C.8 Socioeconomic and Other Resources

C.8.1 Recreational and Commercial Fishing

The main commercial fishing activity in deep waters of the northern Gulf of Mexico is pelagic longlining for tunas, swordfishes, and other billfishes (Continental Shelf Associates, Inc., 2002). Pelagic longlining has occurred historically in the project area, primarily during spring and summer. In August 2000, the Federal government closed two areas in the northeastern Gulf of Mexico to longline fishing (65 Federal Register 47214, 1 August 2000). The lease is outside of

the closure areas.

Longline gear consists of monofilament line deployed from a moving vessel and generally allowed to drift for 4 to 5 hours (Continental Shelf Associates, Inc., 2002). As the mainline is put out, baited leaders and buoys are clipped in place at regular intervals. It takes 8 to 10 hours to deploy a longline and about the same time to retrieve it. Longlines are often set near oceanographic features such as fronts or downwellings, with the aid of sophisticated on-board temperature sensors, depth finders, and positioning equipment. Vessels are 10 to 30 m long, and their trips last from about 1 to 3 weeks. The main homeports for longlining vessels are in Louisiana (Dulac and Venice) and Florida (Destin, Madeira Beach, and Panama City).

It is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. Benthic species targeted by commercial fishers occur on the upper continental slope, well inshore of the project area. Royal red shrimp are caught by trawlers in water depths of about 820 to 1,804 ft (250 to 550 m). Tilefish are caught by bottom longlining in water depths from about 540 to 1,476 ft (165 to 450 m) (Continental Shelf Associates, Inc., 2002). The proposed project is in 7,301 to 7,385 ft (2,225 to 2,251 m) of water. No conflict with commercial fishing activity is expected to occur.

Most recreational fishing activity in the region occurs in water depths less than 656 ft (200 m) (Continental Shelf Associates, Inc., 1997, 2002). In deeper water, the main attraction to recreational fishers would be petroleum platforms in offshore waters of Texas and Louisiana.

The only routine IPF potentially affecting fisheries is drilling rig presence (including noise and lights). Two potential accidents are also addressed below

– a small fuel spill and a large oil spill.

Impacts of Drilling Rig Presence

There is a slight possibility of pelagic longlines becoming entangled in the drilling rig. For example, in January 1999 a portion of a pelagic longline snagged on the acoustic Doppler current profiler of a drillship working in the Gulf of Mexico (Continental Shelf Associates, Inc., 2002). The line was removed without incident. Generally, longline fishers use radar and are aware of offshore structures and ships when placing their sets. Therefore, little or no impact on pelagic longlining is expected.

No adverse impacts on fishing activities are anticipated. Other factors such as effluent discharges are likely to have negligible impacts on commercial or recreational fisheries due to rapid dispersion, the small area of ocean affected, and the intermittent nature of the discharges.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill , implementation of Shell’s OSRP will mitigate and reduce the potential for impacts. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.Pelagic longlining activities in the lease area, if any, could be interrupted in the event of a small fuel spill. The area of the sea surface with diesel fuel on it would range from 1.2 to 12 acres (0.5 to 5 ha), depending on sea state and weather conditions. Fishing activities could be interrupted due to the activities of response vessels operating in the lease area. A small fuel spill would not affect coastal water quality because the spill would not be expected to make landfall or reach coastal waters prior to breaking up (see Section A.9.2 ).

Impacts of a Large Oil Spill

Potential spill impacts on fishing activities are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to this activity.

Pelagic longlining activities in the lease area and other fishing activities in the northern Gulf of Mexico could be interrupted in the event of a large oil spill. A spill may or may not result in fishery closures, depending on the duration of the spill, the oceanographic and meteorological conditions at the time, and the effectiveness of spill response measures. The Macondo spill provides information about the potential extent of fishery closures in the event of a large oil spill in the Gulf of Mexico (NMFS, 2010d). At its peak on 12 July 2010, closures encompassed 217,821 km 2 (84,101 mi 2 ), or 34.8% of the U.S. Exclusive Economic Zone (EEZ) in the Gulf of

Mexico.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on fishing activities are expected.

C.8.2 Public Health and Safety

There are no IPFs associated with routine operations that are expected to affect public health and safety. Impacts of a small fuel spill and a large oil spill are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel tr ansfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts. SEP Sections 2j and 9b provide detail on spill response measures.

A small fuel spill would not have any impacts on public health and safety because it would affect only a small area of the open ocean 75 miles (120 km) from the nearest shoreline and nearly all of the diesel fuel would evaporate or disperse naturally within 24 hours. Response crews would be equipped with appropriate safety equipment to avoid injury and health effects. A small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up (see

Section A.9.2 ).

Impacts of a Large Oil Spill

In the event of a large spill from a blowout, the main safety and health concerns are those of the offshore personnel involved in the incident and those responding to the spill. The proposed activities will be covered by the OSRP, and, in addition, the drilling rig maintains a Shipboard Oil Pollution Emergency Plan as required under MARPOL 73/78.

Depending on the spill rate and duration, the physical/chemical characteristics of the oil, the meteorological and oceanographic conditions at the time, and the effectiveness of spill response measures, the public could be exposed to oil on the water and along the shoreline, through skincontact or inhalation of VOCs. Crude oil is a highly flammable material, and any smoke or vapors from a crude oil fire can cause irritation. Exposure to large quantities of crude oil may pose a

health hazard.

Data from the Macondo spill provide relevant information about the types of health issues that may occur in the event of a large oil spill (Centers for Disease Control and Prevention, 2010a). Wildlife cleaning and rehabilitation workers have reported concerns including scrapes and cuts, itchy or red skin or rash, and symptoms of headache or feeling faint, dizzy, or fatigued. Hand, shoulder, or back pain was also reported by some wildlife-cleaning workers. Personnel working on offshore vessels or providing direct oversight to offshore vessels, including USCG personnel, civilian contractors, and other responders who were exposed to oil and dispersants, had 7 to

12 times higher incidence of upper respiratory symptoms and cough than those not exposed (Centers for Disease Control and Prevention, 2010b). Another potential occupational hazard for spill response workers is exposure to seasonal temperature extremes resulting in heat stress in the summer and hypothermia in the winter. Initial symptoms from cleanup workers who sought medical care in Louisiana were typical of acute exposure to hydrocarbons or H 2 S such as headaches, dizziness, nausea, vomiting, cough, respiratory distress, and chest pain (Solomon and Janssen, 2010). Health effects reported from previous oil spills, such as the Exxon Valdez in 1989, were primarily acute injuries consisting of headaches, throat irritation, and sore or itchy eyes, but respiratory problems and dermatitis along with chronic airway disease have also been reported (Solomon and Janssen, 2010).

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on public health and safety are expected.

C.8.3 Employment and Infrastructure

There are no IPFs associated with routine operations that are expected to affect employment and infrastructure. The project involves drilling with support from existing shorebase facilities in Louisiana. No new or expanded facilities will be constructed, and no new employees are expected to move permanently into the area. The project will have a negligible impact on socioeconomic conditions such as local employment, existing offshore and coastal infrastructure (i ncluding major sources of supplies, services, energy, and water), and minority and lower income groups. Impacts of a small fuel spill and a large oil spill are addressed below.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimize d by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill that is dissipated within a few days would have little or no economic impact, as the spill response would use existing facilities, resources, and personnel.

Impacts of a Large Oil Spill

Potential socioeconomic impacts of an oil spill are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to employment and coastal infrastructure. A large spill could cause economic impacts in several ways: it could result in extensive fishery closures that put fishermen out of work; it could result in temporaryemployment as part of the response effort; it could result in adverse publicity that affects employment in coastal recreation and tourism industries; and it could result in another suspension of OCS drilling activities, including service and support operations that are an important part of local economies.

The lease area is 75 miles (120 km) from the nearest shoreline. Based on OSRA modeling as

summarized in Table 18. 3 , Louisiana, Mississippi, Alabama, and Florida coastal areas are the most likely to be contacted by a spill.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell ’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on employment and infrastructure are expected.

C.8.4 Recreation and Tourism

There are no known recreational uses of the lease area. Recreational resources and tourism in coastal areas would not be affected by any routine activities due to the distance from shore. Compliance with NTL 2007-G03 will minimize the chance of trash or debris being lost overboar d from the drilling rig and subsequently washing up on beaches.

Impacts of a Small Fuel Spill

The probability of a fuel spill will be minimized by Shell’s preventative measures during routine operations including fuel transfer. In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the potential for impacts. SEP Sections 2j and 9b provide detail on spill response measures. Given the open ocean location of the lease area, the duration of a small spill and opportunity for impacts to occur would be very brief.

A small fuel spill in the lease area would be unlikely to affect recreation and tourism. There are no known recreational or tourism activities occurring in the lease area, and as explained in

Section A.9.2 , a small fuel spill would not be expected to make landfall or reach coastal waters prior to breaking up.

Impacts of a Large Oil Spill

Potential impacts of an oil spill on recreation and tourism are discussed in recent EISs (MMS, 2007b, 2008b). For this SEP, there are no unique site-specific issues with respect to these impacts.

Impacts on recreation and tourism would vary depending on the duration of the spill and its fate including the effectiveness of response measures. A large spill that reached coastal waters and shorelines could adversely affect recreation and tourism by contaminating beaches and wetlands, resulting in negative publicity that encourages people to stay away. Based on OSRA modeling as

summarized in Table 18. 3 , areas most likely to be contacted by a spill is Plaquemines Parish,

Louisiana.

In addition to the analysis presented by MMS (2007b, 2008b), recent and ongoing studies have explored the economic impacts of the Macondo spill including tourism and “brand” damage (IEM, 2010; Oxford Economics, 2010). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a 3-year period at $22.7 billion (Oxford Economics, 2010). There are ongoing efforts to accelerate recovery by informing public perceptions; creating travel incentives; and providing access to capital, low interest loans, and tax incentives for affected businesses (U.S. Travel Association, 2010).A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on recreation and tourism are expected.

C.8.5 Land Use

Land use along the northern Gulf Coast is discussed in recent lease sale EISs (MMS, 2007b, 2008b). There are no routine IPFs potentially affecting land use. The project will use existing onshore support facilities in Louisiana. The land use at the existing shorebase sites is industrial. The project will not involve any new construction or changes to existing land use and, therefore, will not have any impacts. Levels of boat and helicopter traffic, as well as demand for goods and services including scarce coastal resources, will represent a small fraction of the level of activity occurring at the shorebases.

A large oil spill is the only relevant accident IPF. A small fuel spill would not have any impacts on land use, as the response would be staged out of existing shorebases and facilities.

Impacts of a Large Oil Spill

The initial response for a large oil spill would be staged out of existing facilities, with no effect on land use. A large spill could have limited temporary impacts on land use along the coast if additional staging areas were needed. For example, during the Macondo spill, temporary staging areas were established in Louisiana, Mississippi, Alabama, and Florida for spill response and cleanup efforts. In the event of a large spill in the lease area, similar temporary staging areas could be needed. These areas would eventually return to their original use as the response is

demobilized.

A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention measures as detailed in SEP Section 2j . In the un likely event of a spill, implementation of Shell’s OSRP will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on land use are expected.

C.8.6 Other Marine Uses

The lease area is located within the Eglin Water Test Area (EWTA) 1 Military Warning Area. Shell will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

There are no IPFs from routine project activities that are likely to affect shipping or other marine uses. A large oil spill is the only relevant accident IPF. A small fuel spill would not have any impacts on other marine uses, as the spill and response activities would be mainly within the

lease area and the duration would be brief.

Impacts of a Large Oil Spill

An accidental spill would be unlikely to significantly affect shipping or other marine uses. The block is not located within any USCG-designated fairway or shipping lane. In the event of a large spill requiring numerous response vessels, coordination would be required to manage the vessel traffic for safe operations. Shell will comply with BOEM requirements and lease stipulations to avoid impacts on uses of the area by military vessels and aircraft.

In the event of a large spill requiring numerous vessels in the area, coordination would be required to ensure that no anchoring or seafloor-disturbing activities occur near the existingpipelines and flowlines. A blowout resulting in a large oil spill is an extremely rare event, and the probability of such an event will be minimized by Shell’s well control and blowout prevention

measures as detailed in SEP Section 2j . In the unlikely event of a spill, implementation of
Shell’s OSR P will mitigate and reduce the impacts. SEP Sections 2j and 9b provide detail on spill response measures. Therefore, no significant spill impacts on other marine uses are expected.

C.9 Cumulative Impacts

For purposes of NEPA, cumulative impact is defined as “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 person undertakes such other actio ns” (40 CFR 1508.7). Any single activity or action may have a negligible impact(s) by itself, but when combined with impacts from other activities in the same area and/or time period, substantial impacts may result.

Prior Studies . MC 393 was acquired in Lease Sale No. 190 on 17 March 2004. Prior to the lease sale, MMS prepared a multi-sale EIS in which it analyzed the environmental impact of activities that might occur in the multi-lease-sale area. The MMS also recently analyzed the cumulative impacts of OCS development activities similar to those planned in this SEP in several documents. The level and types of activities planned in Shell's SEP are within the range of activities described

and evaluated in the Final EIS for Gulf of Mexico OCS Oil and Gas Lease Sales 2007-2012: Western Planning Area Sales 204, 207, 210, 215, and 218, and Central Planning Area Sales 205, 206, 208, 213, 216, and 222 (MMS, 2007b), as updated by a 2008 Final Supplemental EIS for Gulf of Mexico OCS Oil and Gas Lease Sales 2009-2012: Central Planning Area Sales 208, 213, 216, and 222 and Western Planning Area Sales 210, 215, and 218 (MMS, 2008b). Past, present, and reasonably foreseeable activities were identified in the cumulative effects scenario. These documents are incorporated by reference.

Description of Activities Reasonably Expected to Occur in the Vicinity of Project Area . Other exploration and development activities may occur in the vicinity of lease block MC 393.

Cumulative Impacts of Activities in the SEP . The MMS (2007b) multi-lease-sale EIS included a lengthy discussion of cumulative impacts, which analyzed the environmental and socioeconomic impacts from the incremental impact of the 11 proposed lease sales, in addition to all activities (including non-OCS activities) projected to occur from past, proposed, and future lease sales during the 40-year period of 2007 to 2046 (see MMS, 2007b, page 4-301). The EIS considered exploration, delineation, and development wells; platform installation; service-vessel trips; and oil spills. The EIS examined the potential cumulative effects on each specific resource for the entire

Gulf of Mexico.

The level and type of activity proposed in Shell’s SEP are within the range of activities described and evaluated in the recent multi-lease-sale EISs. This EIA incorporates and builds on these analyses by examining the potential impacts on physical, biological, and socioeconomic resources from the work planned in this SEP, in conjunction with the other reasonably foreseeable activities expected to occur in the Gulf of Mexico, as well as the known impacts from the Macondo spill in

MC 252. While another large oil spill could have significant impacts, the numerous new safety measures implemented by the BOEM and further mitigation, and safety measures proposed by Shell in its SEP result in a drilling program that reduces the likelihood of another large spill and improves the effectiveness of any response in the extremely unlikely event that another large spill occurs. Thus, for all impacts , the incremental contribution of Shell’s proposed actions to the cumulative impacts analysis in these prior analyses is not significant.C.9.1 Cumulative Impacts to Physical/Chemical Resources

The work planned in this SEP is limited in geographic scope and duration, and the impacts on the physical/chemical environment will be correspondingly limited.

Air Quality

. Emissions from pollutants into the atmosphere from activities are not projected to have significant effects on onshore air quality because of the prevailing atmospheric conditions, emission rates and heights, and resulting pollutant concentrations. As the BOEM found in the

multi-lease- sale EISs, the incremental contribution of activities similar to Shell’s proposed activities to the cumulative impacts is not significant and will not cause or contribute to a violation of any national ambient air quality standard (MMS, 2007b, 2008b). In addition, the cumulative contribution to visibility impairment is also very small (MMS, 2007b, 2008b). Since

th e BOEM completed the multi-lease-sale EISs, the USEPA has adopted a new short-term NAAQS
for NO 2 and SO 2 . The standard has not yet been implemented in the Gulf of Mexico, but given the levels of expected emissions and the distance of the project from shore, emissions from Shell's SEP are not likely to contribute to violations of any NAAQS onshore.

Climate Change . Carbon dioxide (CO 2 ) and CH 4 emissions from the project would constitute a small incremental contribution to greenhouse gas emissions from all OCS activities. According to the EIS (MMS, 2007a), estimated CO 2 emissions from all OCS activities in the 2007-2012 leasing program are about 0.08% to 0.016% of the global CO 2 emissions from fossil fuel combustion. Greenhouse gas emissions may contribute to climate change, with important effects on temperature, rainfall, frequency of severe weather, ocean acidification, and sea level rise (Intergovernmental Panel on Climate Change, 2007). In the Gulf of Mexico, sea level rise is an important issue due to the ongoing losses in coastal wetlands, particularly in coastal Louisiana. Greenhouse gas emissions from this SEP represent a negligible contribution to the total greenhouse gas emissions from reasonably foreseeable activities in the Gulf of Mexico area and would not significantly alter any of the climate change impacts evaluated in the previous EISs. Globally, Shell is working to reduce greenhouse gas emissions by increasing the efficiency of its operations, establishing a substantial capability in CO 2 capture and storage, and continuing to research and develop technologies that increase efficiency and reduce emissions in hydrocarbon production. 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). Shell’s ongoing efforts to reduce greenhouse gas emissions globally should offset any incremental

contribution from this SEP.

Water Quality . Shell’s project will have some minor water qual ity impacts due to the NPDES-permitted discharge of drilling mud and cuttings, treated sanitary and domestic wastes, excess cement, non-contact cooling water, deck drainage, desalination unit brine, uncontaminated fire water, and ballast water. These effects are expected to be minor (localized to the area within a few hundred meters of the drilling rig), and temporary (lasting only hours longer than the disturbance or discharge). Any cumulative effects to water quality are expected to be negligible.

New Information . The only new, potentially significant information available since preparation of the multi-lease-sale EISs arises from the Macondo spill. The Macondo spill caused short-term, localized air quality impacts (e.g., from evaporation of volatile hydrocarbons and in situ burning of floating oil). Monitoring by the USEPA (2010) has found levels of ozone and particulates ranging from “good” to “unhealthy for sensitive groups” on USEPA’s Air Quality Index; these are at levels well below those that would cause short-term health problems. The air monitoring conducted to date has not found any pollutants at levels expected to cause long-term harm (USEPA, 2010). Satellite imagery indicates that the surface slick from the Macondo spill reached the lease area (ESRI, 2010). However, based on the information currently available, there is noreason to expect any change in air quality conditions or cumulative impacts from those predicted

in the multi-lease-sale EISs.

The Macondo spill also resulted in water quality impacts. In addition to the oil slick on the sea surface, plumes of submerged oil droplets were produced when subsea dispersants were applied at the wellhead (Camilli et al., 2010; Hazen et al., 2010; Joint Analysis Group, 2010a,b,c). Satellite imagery indicates that the surface slick from the Macondo spill reached the lease area (ESRI, 2010), but it is unlikely that subsurface plumes could have permanently affected water quality in or near the lease area. OSAT (2010) reported that, after August 20 10, waters and sediments in the deepwater Gulf of Mexico beyond 1.8 miles (3 km) from the Macondo wellsite were below USEPA acute and chronic benchmarks for PAHs and were not hypoxic. These observations indicate that baseline environmental conditions in the lease area are unlikely to have been significantly altered by the spill. Prior to the incident, water quality in deep, offshore waters was expected to be good, with low levels of contaminants (Kennicutt, 2000). Based on the information currently available, there is no reason to expect any change in water quality conditions or cumulative impacts from those predicted in the multi-lease-sale EISs.

C.9.2 Cumulative Impacts to Biological Resources

The work planned in this SEP is limited in geographic scope and duration, and the impacts on biological resources will be correspondingly limited.

Seafloor Habitats and Biota

. Effects on seafloor habitats and biota from discharges of drilling mud and cuttings are expected to be minor and limited to a small area. There are no areas that may support high-density deepwater benthic communities within 2,000 ft (610 m) of the wellsites, in compliance with NTL 2009-G40. Areas that may support high-density deepwater benthic communities will be avoided as required by NTL 2009-G40. Soft bottom communities are ubiquitous along the northern Gulf of Mexico continental slope, and the extent of benthic impacts during this project is insignificant regionally. As noted in the multi-lease-sale EISs, the

incremental contributions of activities similar to Shell’s proposed activities to the cumulative impacts is not significant (MMS, 2007b).

Threatened, Endangered, and Protected Species . Threatened and endangered species reasonably likely to occur in the lease area include the sperm whale and five species of sea turtles. Potential impact sources include drilling rig presence including noise and lights; marine debris; and support vessel and aircraft traffic. Potential effects for these species would be limited and temporary, and wo uld be reduced by Shell’s compliance with BOEM -required mitigation measures including NTLs 2007-G03 and 2007-G04. No significant cumulative impacts are expected.

Coastal and Marine Birds . Some birds may be attracted to offshore structures because of the lights and the fish populations that aggregate around these structures. Birds that frequent platforms may be exposed to contaminants including air pollutants and routine discharges, but significant impacts are unlikely due to rapid dispersion. Shell’s c ompliance with NTL 2007-G03 will minimize the likelihood of debris-related impacts on birds. Support vessel and helicopter traffic may disturb some foraging and resting birds; however, it is likely that individual birds would experience, at most, only short-term behavioral disruption. Due to the limited scope, timing, and geographic extent of drilling activities, collisions or other adverse effects are unlikely, and no significant cumulative impacts are expected.

Fisheries Resources . Drilling rigs function as FADs for some species of epipelagic fishes; and the aggregations of prey fishes may potentially attract predators. These short-term effects are expected to be small given the isolated nature of the drilling rig and would not be considered a significant impact on pelagic communities, fishery resources, or EFH. Exploration and productionstructures occur in the MC lease block proposed for the exploration activities. The additional effect of the proposed drilling activity would be negligible.

Coastal Habitats . Due to the distance of the wellsites from shore, routine activities are not expected to have any impacts on beaches and dunes, wetlands, seagrass beds, coastal wildlife refuges, wilderness areas, or any other managed or protected coastal area. The support bases at Port Fourchon and Boothville, Louisiana, are not in wildlife refuges or wilderness areas. Support operations, including crew boats and supply boats, may have a minor incremental impact on coastal habitats. Over time with a large number of vessel trips, vessel wakes can erode shorelines along inlets, channels, and harbors. Impacts will be minimized by following the speed

and wake restrictions in harbors and channels.

New Information . The only new, potentially significant information available since preparation of the multi-lease-sale EISs arises from the Macondo spill. The spill has resulted in impacts on biological resources, including visibly oiled and/or dead birds, marine mammals, and sea turtles, as well as oiling of coastal habitats from approximately the Texas/Louisiana border to the Florida Panhandle. Another large spill could result in significant cumulative impacts to these resources. However, for the reasons discussed in this SEP, Shell’s NTL 2010-N06 response, and the OSRP, the likelihood of a catastrophic well control event resulting in significant amounts of oil in the water is extremely remote. Therefore, Shell’s proposed activities are not expected to result in any cumulative impacts to biological resources affected by the Macondo spill, nor should they have any impact on the previously conducted cumulative impact analyses.

Regarding deepwater benthic communities, the multi-lease-sale EISs (MMS, 2007a, 2008b) concluded that oil spills would be unlikely to affect benthic communities beyond the immediate vicinity of the wellhead (i.e., due to physical impacts of a blowout) because the oil would rise quickly to the sea surface directly over the spill location. However, during the Macondo spill, subsurface plumes were reported at a water depth of about 3,600 ft (1,100 m), extending at least 22 miles (35 km) from the wellsites and persisting for more than a month (Camilli et al., 2010). The subsurface plumes apparently resulted from the use of dispersants at the wellhead (J oint Analysis Group, 2010c). This observation is supported by Kujawinski et al. (2011) in their report that chemical components of subsea dispersants used during the Macondo spill persisted for up to two months and were detected up to 186 miles (300 km) from the wellsite at a water depth of 3,280 to 3,937 ft (1,000 to 1,200 m). However, estimated dispersant concentrations in the subsea plume were below levels known to be toxic to marine life. While the behavior and impacts of subsurface plumes are not well known, a subsurface plume could contact the seafloor and affect benthic communities beyond the 984-ft (300-m) radius estimated by MMS (2007a, 2008b), depending on its extent, trajectory, and persistence. This contact could result in smothering and/or toxicity to benthic organisms. The affected area would be recolonized by benthic organisms over a period of months to years (NRC, 2003).

C.9.3 Cumulative Impacts to Socioeconomic Resources

The work planned in this SEP is limited in geographic scope and duration, and the impacts on socioeconomic resources will be correspondingly limited.

Archaeological Resources . MC 393 is not on the list of leases with a high potential for historic shipwrecks (MMS, 2008a). An archaeological assessment by Fugro Geoservices, Inc. (2007, 2009a, 2011) indicated that one of the sonar contacts in the lease area could not be reliably identified and will be avoided during anchor placement. Also, the lease area is well beyond the 197-ft (60-m) depth contour used by the BOEM as the seaward extent for prehistoric archaeological site potential in the Gulf of Mexico. Therefore, Shell’s operations will have no cumulative impacts on historic shipwrecks or prehistoric archaeological resources.Socioeconomic Resources . The multi-lease- sa le EISs analyzed the cumulative impacts of oil and gas exploration and development in the lease area, in combination with other impact-producing activities, on commercial fishing, recreational fishing, recreational resources, historical and archaeological resources, land use and coastal infrastructure, demographics, and environmental justice (MMS, 2007b). The EISs also analyzed the economic impact of oil and gas activities on the Gulf States, finding only minor impacts in most of Texas, Mississippi, Alabama, and Florida, more significant impact in parts of Texas, and substantial impact on Louisiana.

Shell’s proposed activities will have negligible cumulative impacts on socioeconomic resources. There are no IPFs associated with routine operations that are expected to affect public health and safety, employment and infrastructure, recreation and tourism, land use, or other marine uses. Due to the distance from shore, it is unlikely that any recreational fishing activity is occurring in the project area, and it is unlikely that any commercial fishing activity other than longlining occurs at or near the project area. The project will have negligible impacts on fishing

activities.

New Information . The only new, potentially significant information available since preparation of the multi-lease-sale EISs arises from the Macondo spill. The spill has resulted in impacts on commercial and recreational fishing, recreation and tourism, employment, and public health and safety. The Macondo spill resulted in extensive fishery closures in the Gulf of Mexico, peaking at 34.8% of the EEZ in the Gulf of Mexico (NMFS, 2010d). The U.S. Travel Association has estimated the economic impact of the Macondo spill on tourism across the Gulf Coast over a 3- year period at $22.7 billion (Oxford Economics, 2010). Reported health impacts (e.g., among spill response and wildlife rehabilitation workers) ranged from cuts and scrapes, to upper respiratory symptoms and heat stress, to acute exposure to hydrocarbons or H 2 S (Centers for Disease Control and Prevention, 2010a,b; Solomon and Janssen, 2010). Most of these impacts were temporary in nature, although health exposure of clean-up workers could have longer-lasting impacts.

However, for the reasons discussed in this SEP, Shell’s NTL 2010 -N06 response, and the OSRP, the likelihood of a catastrophic well control event resulting in significant amounts of oil in the water is extremely remote. Therefore, Shell’s proposed activities are not expected to result in any cumulative impacts to socioeconomic resources affected by the Macondo spill, nor should they have any impact on the previously conducted cumulative impact analyses.

D. Environmental Hazards

D.1 Geologic Hazards

The shallow hazards assessment included in this SEP, based on the shallow hazards report by

AOA Geophysics, Inc. (2004) and Fugro Geoservices, Inc. (2007, 2009a, 2011 ) reports that the wellsites are free of any major geological hazards and are suitable for the proposed activities. There are no fluid expulsion features or faults within 2,000 ft (600 m) of the well proposed locations based on results of a high-resolution geophysical survey consisting of frequency-enhanced 3-D seismic, enhanced surface renderings, autonomous underwater vehicle (AUV) surveys, and side-scan sonar. There are previously drilled wells in the vicinity of the proposed locations but none are within 2,000 ft (600m) ( AOA Geophysics, Inc., 2004 ; Geoservices, Inc.

, 2007, 2009b, 2011 ).

See SEP Section 6a for supporting geological and geophysical information.D.2 Severe Weather

Under most circumstances, weather is not expected to have any effect on the proposed activities. Extreme weather, including high winds, strong currents, and large waves, was considered in the design criteria for the drilling rig. High winds and limited visibility during a severe storm could disrupt communication and support activities (vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes. In the event of a hurricane, procedures in Shell’s Hurricane Evacuation Plan would be

followed.

D.3 Currents and Waves

A rig-based acoustic Doppler current profiler will be used to continuously monitor the current beneath the rig. Metocean conditions such as sea states, wind speed, ocean currents, etc. will also be continuously monitored. Under most circumstances, physical oceanographic conditions are not expected to have any effect on the proposed activities. Strong currents (e.g., caused by Loop Current eddies and intrusions) and large waves were considered in the design criteria for the drilling rig. High waves during a severe storm could disrupt support activities (i.e., vessel and helicopter traffic) and make it necessary to suspend some activities on the drilling rig for safety reasons until the storm or weather event passes.

E. Alternatives

No formal alternatives were evaluated in this EIA. However, various technical and operational options, including the location of the wellsites and the selection of a drilling unit, were considered by Shell in developing the proposed action. There are no other reasonable alternatives to accomplish the goals of this project.

F. Mitigation Measures

The proposed action includes numerous mitigation measures required by laws, regulations, and BOEM lease stipulations and NTLs. The project will comply with applicable Federal, State, and local requirements concerning air pollutant emissions, discharges to water, and solid waste disposal. All project a ctivities will be conducted under Shell’s OSRP and will include the measures

described in SEP Section 2f

.

G. Consultation

No persons or agencies were consulted regarding potential impacts associated with the proposed activities during the preparation of this EIA.H. Preparers

The EIA was prepared at the direction of Shell Offshore Inc. by its contractor, CSA International, Inc. Contributors included the following:

Sylvia Bellone (Regulatory Specialist, Shell Exploration & Production Co.); Tracy Albert (Regulatory Specialist, Offshore Technical Compliance LLC); Lori Downs (Environmental Team Leader, Shell Exploration & Production Co.); Jeffrey McMenis, (Environmental Engineer, Shell Exploration & Production Co.); Rob Kuehn (Environmental Engineer, Shell Exploration & Production Co.); Patrick Jackson (Prospect Team Lead, Corinth Development, Shell Exploration & Production Co.); John Harris (Geologist, Corinth Development, Shell Exploration & Production Co.); Pilar Rojas (PDT Team Leader, Corinth Development, Shell Exploration & Production Co.); Chris Brinkman (Drilling Engineer, Corinth Development, Shell Exploration & Production Co.); Ismail Barutcu (Reservoir Engineer, Corinth Development, Shell Exploration & Production Co.); June Mire, Ph.D. (Senior Ecologist and Project Manager, Tetra Tech EM, Inc.); Cindy Chandool, Ph.D. (Senior Scientist, CSA International, Inc.); Carlyle Kalloo (Senior Scientist, CSA International, Inc.); Neal Phillips, Ph.D. (Senior Scientist, CSA International, Inc.); Deborah Fawcett (Project Scientist II, CSA International, Inc.); Stephen Viada (Senior Scientist, CSA International, Inc.); Keith VanGraafeiland (GIS/Remote Sensing Specialist, CSA International, Inc.); and Danielle Johnson (Technical Editor, CSA International, Inc.).

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University Press, College Station, TX. 232 pp.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 3g. High-Resolution Seismic Lines & Top Hole Progs Sections 3h. & 3i. Stratigraphic Column with Time vs. depth table

B. Bibliography

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Fugro GeoConsulting, Inc. (2009), “Shallow Drilling Hazards and Archaeological Assessment, Mississippi Canyon Blocks 347, 348, 391, 392 and Vicinity, Gulf of Mexico”, Fugro Report No. 27.2008 -5022, prepared for Shell Exploration and Production Company.

Fugro Geoservices, Inc (2007) Archaeological Assessment, Proposed Anchor Locations Block 393, Mississippi Canyon Area, Gulf of Mexico”, Fugro Report No. 2407 -1083, prepared for Shell Deepwater Development.

AOA Geophysics, Inc. (2004), “Shallow Hazards Assessment MC393 (OCS G-26254), DC353 (OCS G-25852), DC354 (OCS G-23507), DC397 (OCS G-25853), AND DC398 (OCS G-25854) Mississippi Canyon and DeSoto Canyon Areas, Gulf of

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